Improved Blue Carba test and Carba NP test for detection and classification of major Class A and B carbapenemases, including dual producers, among Gram-negative bacilli.

Prompt and precise identification of carbapenemase-producing organisms is crucial for guiding clinical antibiotic treatments and limiting transmission. Here, we propose modifying the Blue Carba test (BCT) and Carba NP-direct (CNPd) to identify molecular carbapenemase classes, including dual carbapenemase strains, by adding specific Class A and Class B inhibitors. We tested 171 carbapenemase-producing Gram-negative bacilli strains-21 in Class A (KPC, NMC, SME), 58 in Class B (IMP, VIM, NDM, SPM), and 92 with dual carbapenemase production (KPC+NDM, KPC+IMP, KPC+VIM), all previously positive with BCT or CNPd. We also included 13 carbapenemase non-producers. ß-lactamases were previously characterized by PCR. The improved BCT/CNPd methods detect imipenem hydrolysis from an imipenem-cilastatin solution, using pH indicators and Class A (avibactam) and/or Class B (EDTA) inhibitors. Results were interpreted visually based on color changes. CNPd achieved 99.4% sensitivity and 100% specificity in categorizing carbapenemases, while BCT had 91.8% sensitivity and 100% specificity. Performance varied by carbapenemase classes: both tests classified all Class A-producing strains. For Class B, the CNP test identified 57/58 strains (98.3%), whereas the BCT test, 45/58 strains (77.6%), with non-fermenters posing the greatest detection challenge. For Classes A plus B dual producers, both tests performed exceptionally well, with only one indeterminate strain for the BCT. The statistical comparison showed both methods had similar times to a positive result, with differences based on the carbapenemase class or bacterial group involved. This improved assay rapidly distinguishes major Class A or Class B carbapenemase producers among Gram-negative bacilli, including dual-class combinations, in less than 2 hours. IMPORTANCE: Rapid and accurate identification of carbapenemase-producing organisms is of vital importance in guiding appropriate clinical antibiotic treatments and curbing their transmission. The emergence of negative bacilli carrying multiple carbapenemase combinations during and after the severe acute respiratory syndrome coronavirus 2 pandemic has posed a challenge to the conventional biochemical tests typically used to determine the specific carbapenemase type in the isolated strains. Several initiatives have aimed to enhance colorimetric methods, enabling them to independently identify the presence of Class A or Class B carbapenemases. Notably, no previous efforts have been made to distinguish both classes simultaneously. Additionally, these modifications have struggled to differentiate between carriers of multiple carbapenemases, a common occurrence in many Latin American countries. In this study, we introduced specific Class A and Class B carbapenemase inhibitors into the Blue Carba test (BCT) and Carba NP-direct (CNP) colorimetric assays to identify the type of carbapenemase, even in cases of multiple carbapenemase producers within these classes. These updated assays demonstrated exceptional sensitivity and specificity (≥ 90%) all within a rapid turnaround time of under 2 hours, typically completed in just 45 minutes. These in-house enhancements to the BCT and CNP assays present a rapid, straightforward, and cost-effective approach to determining the primary carbapenemase classes. They could serve as a viable alternative to molecular biology or immuno-chromatography techniques, acting as an initial diagnostic step in the process.

KPC-2 allelic variants in Klebsiella pneumoniae isolates resistant to ceftazidime-avibactam from Argentina: blaKPC-80, blaKPC-81, blaKPC-96 and blaKPC-97.

Ceftazidime-avibactam (CZA) therapy has significantly improved survival rates for patients infected by carbapenem-resistant bacteria, including KPC producers. However, resistance to CZA is a growing concern, attributed to multiple mechanisms. In this study, we characterized four clinical CZA-resistant Klebsiella pneumoniae isolates obtained between July 2019 and December 2020. These isolates expressed novel allelic variants of blaKPC-2 resulting from changes in hotspots of the mature protein, particularly in loops surrounding the active site of KPC. Notably, KPC-80 had an K269_D270insPNK mutation near the Lys270-loop, KPC-81 had a del_I173 mutation within the Ω-loop, KPC-96 showed a Y241N substitution within the Val240-loop and KPC-97 had an V277_I278insNSEAV mutation within the Lys270-loop. Three of the four isolates exhibited low-level resistance to imipenem (4 µg/mL), while all remained susceptible to meropenem. Avibactam and relebactam effectively restored carbapenem susceptibility in resistant isolates. Cloning mutant blaKPC genes into pMBLe increased imipenem MICs in recipient Escherichia coli TOP10 for blaKPC-80, blaKPC-96, and blaKPC-97 by two dilutions; again, these MICs were restored by avibactam and relebactam. Frameshift mutations disrupted ompK35 in three isolates. Additional resistance genes, including blaTEM-1, blaOXA-18 and blaOXA-1, were also identified. Interestingly, three isolates belonged to clonal complex 11 (ST258 and ST11) and one to ST629. This study highlights the emergence of CZA resistance including unique allelic variants of blaKPC-2 and impermeability. Comprehensive epidemiological surveillance and in-depth molecular studies are imperative for understanding and monitoring these complex resistance mechanisms, crucial for effective antimicrobial treatment strategies. IMPORTANCE: The emergence of ceftazidime-avibactam (CZA) resistance poses a significant threat to the efficacy of this life-saving therapy against carbapenem-resistant bacteria, particularly Klebsiella pneumoniae-producing KPC enzymes. This study investigates four clinical isolates exhibiting resistance to CZA, revealing novel allelic variants of the key resistance gene, blaKPC-2. The mutations identified in hotspots surrounding the active site of KPC, such as K269_D270insPNK, del_I173, Y241N and V277_I278insNSEAV, prove the adaptability of these pathogens. Intriguingly, low-level resistance to imipenem and disruptions in porin genes were observed, emphasizing the complexity of the resistance mechanisms. Interestingly, three of four isolates belonged to clonal complex 11. This research not only sheds light on the clinical significance of CZA resistance but also shows the urgency for comprehensive surveillance and molecular studies to inform effective antimicrobial treatment strategies in the face of evolving bacterial resistance.

Different evolution of S. aureus methicillin-resistant and methicillin-susceptible infections, Argentina.

Staphylococcus aureus-(SA) is widespread among healthcare-associated-(HA) and the community-associated-(CA) infections. However, the contributions of MRSA and MSSA to the SA overall burden remain unclear. In a nationally-representative-survey conducted in Argentina, 668 SA clinical isolates from 61 hospitals were examined in a prospective, cross-sectional, multicenter study in April 2015. The study aimed to analyze MRSA molecular epidemiology, estimate overall SA infection incidence (MSSA, MRSA, and genotypes) in community-onset (CO: HACO, Healthcare-Associated-CO and CACO, Community-Associated-CO) and healthcare-onset (HO: HAHO, Healthcare-associated-HO) infections, stratified by age groups. Additionally temporal evolution was estimated by comparing this study's (2015) incidence values with a previous study (2009) in the same region. Erythromycin-resistant-MSSA and all MRSA strains were genetically typed. The SA total-infections (TI) overall-incidence was 49.1/100,000 monthly-visits, 25.1 and 24.0 for MRSA and MSSA respectively (P = 0.5889), in April 2015. In adults with invasive-infections (INVI), MSSA was 15.7 and MRSA was 11.8 (P = 0.0288), 1.3-fold higher. HA SA infections, both MSSA and MRSA, surpassed CA infections by over threefold. During 2009-2015, there was a significant 23.4 % increase in the SA infections overall-incidence, mainly driven by MSSA, notably a 54.2 % increase in INVI among adults, while MRSA infection rates remained stable. The MSSA rise was accompanied by increased antimicrobial resistance, particularly to erythromycin, linked to MSSA-CC398-t1451-ermT + -IEC+-pvl- emergence. The SA-infections rise was primarily attributed to community-onset-infections (37.3 % and 62.4 % increase for TI and INVI, respectively), particularly HACO-MSSA and HACO-MRSA in adults, as well as CACO-MSSA. The main CA-MRSA-PFGE-typeN-ST30-SCCmecIVc-PVL+/- clone along with other clones (USA300-ST8-IV-LV-PVL+/-, PFGE-typeDD-ST97-IV- PVL-) added to rather than replaced CA-MRSA-PFGE-typeI-ST5-SCCmecIVa-PVL+/- clone in HA invasive-infections. They also displaced clone HA-MRSA-PFGE-typeA-ST5-SCCmecI, mainly in HAHO infections. The overall-burden of SA infections is rising in Argentina, driven primarily by community-onset MSSA, particularly in adults, linked to increased erythromycin-resistance and MSSA-CC398-t1451-ermT + -IEC+-pvl- emergence. Novel knowledge and transmission-control strategies are required for MSSA.

Emergence of optrA-mediated linezolid resistance in clinical isolates of Enterococcus faecalis from Argentina.

OBJECTIVES: The aim of this study was to characterize the first 14 optrA-carrying linezolid resistant E. faecalis clinical isolates recovered in seven Argentinian hospitals between 2016 and 2021. The epidemiology of optrA-carrying isolates and the optrA genetic context were determined. METHODS: The isolates were phenotypically and genotypically characterized. Susceptibility to 13 antimicrobial agents was performed; clonal relationship was assessed by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Data provided by the whole-genome sequencing were used for identification of sequence types, antimicrobial resistance genes, optrA variants, phylogenetic tree, and mobile genetic elements responsible to the dissemination of these strains. RESULTS: All the optrA-carrying E. faecalis isolates were multidrug-resistant and harboured several antimicrobial resistance genes. They carried three optrA variants and belonged to different lineages; however, three of them belonged to the hyperepidemic CC16. Mobile genetic elements were detected in all the isolates. The analysis of the optrA flanking region suggests the plasmidic localization in most of the isolates. CONCLUSIONS: To the best of our knowledge, this is the first report of optrA-mediated linezolid resistance in Argentina. The emergence and dissemination of the optrA genes in clinical E. faecalis isolates are of concern and highlights the importance of initiating the antimicrobial surveillance of Enterococcus spp. under a One Health strategy.

Emergence of Hyper-Epidemic Clones of Enterobacterales Clinical Isolates Co-Producing KPC and Metallo-Beta-Lactamases during the COVID-19 Pandemic.

BACKGROUND: The global spread of carbapenemase-producing Enterobacterales has become an epidemiological risk for healthcare systems by limiting available antimicrobial treatments. The COVID-19 pandemic worsened this scenario, prompting the emergence of extremely resistant microorganisms. METHODS: Between March 2020 and September 2021, the NRL confirmed 82 clinical Enterobacterales isolates harboring a combination of blaKPC and MBL genes. Molecular typing was analyzed by PFGE and MLST. Modified double-disk synergy (MDDS) tests were used for phenotypic studies. RESULTS: Isolates were submitted from 28 hospitals located in seven provinces and Buenos Aires City, including 77 K. pneumoniae, 2 K. oxytoca, 2 C. freundii, and 1 E. coli. Almost half of K. pneumoniae isolates (n = 38; 49.4%), detected in 15 hospitals, belong to the CC307 clone. CC11 was the second clone, including 29 (37.7%) isolates (22, ST11 and 7, ST258) from five cities and 12 hospitals. Three isolates belonging to CC45 were also detected. The carbapenemase combinations observed were as follows: 55% blaKPC-2 plus blaNDM-5; 32.5% blaKPC-2 plus blaNDM-1; 5% blaKPC-3 plus blaNDM-1; 5% blaKPC-2 plus blaIMP-8; and 2.5% strain with blaKPC-2 plus blaNDM-5 plus blaOXA-163. Aztreonam/avibactam and aztreonam/relebactam were the most active combinations (100% and 91% susceptible, respectively), followed by fosfomycin (89%) and tigecycline (84%). CONCLUSIONS: The MDDS tests using ceftazidime-avibactam/EDTA and aztreonam/boronic acid disks improved phenotypic classification as dual producers. The successful high-risk clones of K. pneumoniae, such as hyper-epidemic CC307 and CC11 clones, drove the dissemination of double carbapenemase-producing isolates during the COVID-19 pandemic.

Carbapenemase-Producing Extraintestinal Pathogenic Escherichia coli From Argentina: Clonal Diversity and Predominance of Hyperepidemic Clones CC10 and CC131.

Extraintestinal pathogenic Escherichia coli (ExPEC) causes infections outside the intestine. Particular ExPEC clones, such as clonal complex (CC)/sequence type (ST)131, have been known to sequentially accumulate antimicrobial resistance that starts with chromosomal mutations against fluoroquinolones, followed with the acquisition of bla CTX-M-15 and, more recently, carbapenemases. Here we aimed to investigate the distribution of global epidemic clones of carbapenemase-producing ExPEC from Argentina in representative clinical isolates recovered between July 2008 and March 2017. Carbapenemase-producing ExPEC (n = 160) were referred to the Argentinean reference laboratory. Of these, 71 were selected for genome sequencing. Phenotypic and microbiological studies confirmed the presence of carbapenemases confirmed as KPC-2 (n = 52), NDM-1 (n = 16), IMP-8 (n = 2), and VIM-1 (n = 1) producers. The isolates had been recovered mainly from urine, blood, and abdominal fluids among others, and some were from screening samples. After analyzing the virulence gene content, 76% of the isolates were considered ExPEC, although non-ExPEC isolates were also obtained from extraintestinal sites. Pan-genome phylogeny and clonal analysis showed great clonal diversity, although the first phylogroup in abundance was phylogroup A, harboring CC10 isolates, followed by phylogroup B2 with CC/ST131, mostly H30Rx, the subclone co-producing CTX-M-15. Phylogroups D, B1, C, F, and E were also detected with fewer strains. CC10 and CC/ST131 were found throughout the country. In addition, CC10 nucleated most metalloenzymes, such as NDM-1. Other relevant international clones were identified, such as CC/ST38, CC155, CC14/ST1193, and CC23. Two isolates co-produced KPC-2 and OXA-163 or OXA-439, a point mutation variant of OXA-163, and three isolates co-produced MCR-1 among other resistance genes. To conclude, in this work, we described the molecular epidemiology of carbapenemase-producing ExPEC in Argentina. Further studies are necessary to determine the plasmid families disseminating carbapenemases in ExPEC in this region.

Simple Phenotypic Tests To Improve Accuracy in Screening Chromosomal and Plasmid-Mediated Colistin Resistance in Gram-Negative Bacilli.

CLSI and EUCAST recommend that only broth microdilution (BMD) should be used for routine colistin susceptibility testing; however, this technique can be difficult to perform in resource-poor settings. The purpose of this study was to evaluate the accuracy of a colistin agar spot test (COL-AS) and a colistin drop test (COL-DT) compared to BMD. COL-AS and COL-DT were assessed with a collection of 271 Gram-negative bacilli clinical isolates: 195 Enterobacterales (including 63 mcr-1 positive strains), 37 Acinetobacter spp., and 39 Pseudomonas aeruginosa For COL-AS, 3.0 µg/ml (final concentration) of colistin was added to a Mueller-Hinton agar plate and subsequently swabbed with a 0.5 McFarland standard suspension of the tested strain within a 1 cm2 spot. For COL-DT, 10 µl of a 16 µg/ml colistin solution was dripped on the surface of a Mueller-Hinton agar plate, previously inoculated with a lawn of the tested strain (0.5 McFarland standard). Colistin solution was made either by dissolving powder or by disk elution in cation-adjusted Mueller-Hinton broth (CA-MHB). Overall, 141/271 (52%) isolates were categorized as colistin resistant by reference BMD. COL-AS yielded a categorical agreement (CA) of 95.5% compared to BMD, with 0.7% very major errors and 3.8% major errors. COL-DT yielded a CA of 96.2% compared to BMD, with 0.7% and 0% very major errors and 3.1% and 3.8% major errors, for colistin powder and disk elution solutions, respectively. Most major errors occurred for mcr-1 strains with MICs that fluctuated from 2 to 4 µg/ml according to the method used. In conclusion, we developed and validated methods suited to the systematic screening of resistance to colistin in Gram-negative bacilli.

Plasmidic resistance to colistin mediated by mcr-1 gene in Escherichia coli clinical isolates in Argentina: A retrospective study, 2012-2018.

OBJECTIVE: To describe the resistance profile and the genetic characteristics of Escherichia coli isolates that harbor the mobilizable colistin resistance gene mcr-1 in Argentina. METHODS: This was a retrospective study of 192 E. coli isolates positive for mcr-1 obtained from 69 hospitals of Buenos Aires City and 14 Argentinean provinces in 2012 - 2018. The antimicrobial susceptibility was performed by agar diffusion, broth macrodilution, and/or agar dilution. Standard polymerase chain reaction (PCR) was performed to detect resistance genes and incompatibility groups; specific PCR was applied to discriminate between blaCTX-M allelic groups and mcr-1.5 variant. The genetic relatedness among isolates was evaluated by XbaI-pulsed field gel electrophoresis and multilocus sequence typing in a subset of isolates. RESULTS: All E. coli isolates showed minimal inhibitory concentrations to colistin ≥ 4µg/mL; nearly 50% were resistant to third-generation cephalosporins, with CTX-M-2 being the main extended-spectrum ß-lactamase detected. Five E. coli were carbapenemase-producers (3 NDM, 2 KPC). The mcr-1.5 variant was detected in 13.5% of the isolates. No genetic relationship was observed among the mcr-1-positive E. coli clinical isolates, but a high proportion (164/192; 85.4%) of IncI2 plasmids was detected. CONCLUSIONS: The presence of IncI2 plasmids among highly diverse E. coli clones suggests that the mcr-1 gene's wide distribution in Argentina may be driven by the horizontal transmission of IncI2 plasmids.

Plasmidic resistance to colistin mediated by mcr-1 gene in Escherichia coli clinical isolates in Argentina: A retrospective study, 2012–2018

[ABSTRACT]. Objective. To describe the resistance profile and the genetic characteristics of Escherichia coli isolates that harbor the mobilizable colistin resistance gene mcr-1 in Argentina. Methods. This was a retrospective study of 192 E. coli isolates positive for mcr-1 obtained from 69 hospitals of Buenos Aires City and 14 Argentinean provinces in 2012 – 2018. The antimicrobial susceptibility was performed by agar diffusion, broth macrodilution, and/or agar dilution. Standard polymerase chain reaction (PCR) was performed to detect resistance genes and incompatibility groups; specific PCR was applied to discriminate between blaCTX-M allelic groups and mcr-1.5 variant. The genetic relatedness among isolates was evaluated by XbaI-pulsed field gel electrophoresis and multilocus sequence typing in a subset of isolates. Results. All E. coli isolates showed minimal inhibitory concentrations to colistin ≥ 4μg/mL; nearly 50% were resistant to third-generation cephalosporins, with CTX-M-2 being the main extended-spectrum β-lactamase detected. Five E. coli were carbapenemase-producers (3 NDM, 2 KPC). The mcr-1.5 variant was detected in 13.5% of the isolates. No genetic relationship was observed among the mcr-1-positive E. coli clinical isolates, but a high proportion (164/192; 85.4%) of IncI2 plasmids was detected. Conclusions. The presence of IncI2 plasmids among highly diverse E. coli clones suggests that the mcr-1 gene’s wide distribution in Argentina may be driven by the horizontal transmission of IncI2 plasmids.

[RESUMEN]. Objetivo. Describir el perfil de resistencia y las características genéticas de aislamientos clínicos de Escherichia coli que portan el gen movilizable de resistencia a colistina mcr-1 en Argentina. Métodos. Se realizó un estudio retrospectivo para analizar 192 aislamientos de E. coli mcr-1 positivo, obtenidos en 69 hospitales de la Ciudad de Buenos Aires y 14 provincias de Argentina entre 2012 y 2018. La sensibilidad a los antimicrobianos se analizó mediante los métodos de difusión en agar, macrodilución en caldo y/o dilución en agar. Se aplicó la técnica estándar de reacción en cadena de la polimerasa (PCR) para detectar genes de resistencia y grupos de incompatibilidad; se aplicó PCR específica para distinguir entre variantes alélicas del gen blaCTX-M y la variante mcr-1.5. La relación genética entre los aislamientos fue evaluada mediante la técnica de electroforesis en gel de campo pulsado usando la enzima Xbal y la tipificación por secuencias de múltiples locus en un subconjunto de aislamientos. Resultados. Todos los aislamientos de E. coli mostraron concentraciones inhibitorias mínimas de colistina ≥ 4μg/mL. Casi el 50% mostró resistencia a las cefalosporinas de tercera generación y CTX-M-2 fue la β-lactamasa de espectro extendido que más se detectó. Cinco aislamientos de E. coli mostraron ser productoras de carbapenemasas (3 NDM, 2 KPC). La variante mcr-1.5 se detectó en 13,5% de las cepas aisladas. No se observó relación genética entre los aislamientos clínicos estudiados de E. coli positivas para mcr-1, aunque sí se detectó una proporción elevada (164/192; 85,4%) de plásmidos Incl2. Conclusiones. La elevada ocurrencia de plásmidos IncI2 en un grupo altamente diverso de clones de E. coli podría indicar que la amplia difusión del gen mcr-1 en Argentina estaría asociada a la transmisión horizontal de plásmidos IncI2.

[RESUMO]. Objetivo. Descrever o perfil de resistência e as características genéticas de isolados clínicos de Escherichia coli que carregam o gene mobilizábel de resistência à colistina mcr-1 na Argentina. Métodos. Neste estudo retrospectivo, foram analizados 192 isolados de E. coli positivos para mcr-1 obtidos em 69 hospitais da Cidade de Buenos Aires e 14 províncias da Argentina, entre 2012 e 2018. A sensibilidade aos antimicrobianos foi examinada usando métodos de difusão em ágar, macrodiluição em caldo e/ou diluição em ágar. A técnica padrão de reação em cadeia da polimerase (PCR) foi aplicada para detectar genes de resistência e grupos de incompatibilidade; a PCR específica foi aplicada para discriminar entre variantes alélicas do gene blaCTX-M e a variante mcr-1.5. A relação genética entre os isolados foi avaliada por eletroforese em gel de campo pulsado usando a enzima XbaI e a tipagem por sequências de múltiplos lócus, em um subconjunto de isolados. Resultados. Todos os isolados de E. coli apresentaram concentrações inibitórias mínimas de colistina ≥4μg/ mL. Quase 50% foram resistentes às cefalosporinas de terceira geração, e CTX-M-2 foi a β-lactamase de espectro estendido mais detectada. Cinco isolados de E. coli foram produtores de carbapenemase (3 NDM, 2 KPC). A variante mcr-1.5 foi detectada em 13,5% dos isolados. Não foi observada relação genética entre os isolados clínicos de E. coli positivos para mcr-1, mas foi detectada uma alta proporção (164/192; 85,4%) de plasmídeos IncI2. Conclusões. A alta ocorrência de plasmídeos IncI2 em um grupo altamente diverso de clones de E. coli sugere que a ampla distribuição do gene mcr-1 na Argentina estaria associada a transmissão horizontal de plasmídeos IncI2.

Consenso Argentino intersociedades de Infección Urinaria 2018-2019 - Parte I / Consenso Argentino Intersociedades de Infección Urinaria 2018-2019 - Parte I

La Sociedad Argentina de Infectología y otras sociedades científicas han actualizado estas recomendaciones utilizando, además de información internacional, la de un estudio multicéntrico prospectivo sobre infecciones del tracto urinario del adulto realizado en Argentina durante 2016-2017. La bacteriuria asintomática debe ser tratada solo en embarazadas, a quienes también se las debe investigar sistemáticamente; los antibióticos de elección son nitrofurantoína, amoxicilina, amoxicilina-clavulánico, cefalexina y trimetoprima-sulfametoxazol. Ante procedimientos que impliquen lesión con sangrado del tracto urinario se recomienda solicitar urocultivo para pesquisar bacteriuria asintomática, y, si resultara positivo, administrar antimicrobianos según sensibilidad desde inmediatamente antes hasta 24 horas luego de la intervención. En mujeres, la cistitis puede ser tratada con nitrofurantoina, cefalexina, o fosfomicina y no se recomienda usar trimetoprima-sulfametoxazol o fluoroquinolonas; en pielonefritis puede emplearse ciprofloxacina, cefixima o cefalexina si el tratamiento es ambulatorio o ceftriaxona, cefazolina o amikacina si es hospitalario. En los hombres, las infecciones del tracto urinario se consideran siempre complicadas. Se recomienda tratamiento con nitrofurantoina o cefalexina por 7 días, o bien monodosis con fosfomicina. Para la pielonefritis en hombres se sugiere ciprofloxacina, ceftriaxona o cefixima si el tratamiento es ambulatorio y ceftriaxona o amikacina si es hospitalario. Se sugiere tratar las prostatitis bacterianas agudas con ceftriaxona o gentamicina. En cuanto a las prostatitis bacterianas crónicas, si bien su tratamiento de elección hasta hace poco fueron las fluoroquinolonas, la creciente resistencia y ciertas dudas sobre la seguridad de estas drogas obligan a considerar el uso de alternativas como fosfomicina.

The Argentine Society of Infectious Diseases and other scientific societies have updated these recommendations based on data on urinary tract infections in adults obtained from a prospective multicenter study conducted in Argentina during 2016-2017. Asymptomatic bacteriuria should be treated only in pregnant women, who should also be systematically investigated; the antibiotics of choice are nitrofurantoin, amoxicillin, clavulanic/amoxicillin, cephalexin and trimethoprim-sulfamethoxazole. In procedures involving injury to the urinary tract with bleeding, it is recommended to request urine culture and, in the presence of bacteriuria, antimicrobial treatment according to sensitivity should be prescribed from immediately before up to 24 hours after the intervention. In women, cystitis can be treated with nitrofurantoin, cephalexin or fosfomycin, while trimethoprim-sulfamethoxazole and fluoroquinolones are not recommended; pyelonephritis can be treated with ciprofloxacin, cefixime or cephalexin in ambulatory women or ceftriaxone, cefazolin or amikacin in those who are hospitalized. In men, urinary tract infections are always considered complicated; nitrofurantoin or cephalexin are recommended for 7 days, alternatively fosfomycin should be given in a single dose. In men, ciprofloxacin, ceftriaxone or cefixime are suggested for pyelonephritis on ambulatory treatment whereas ceftriaxone or amikacin are recommended for hospitalized patients. Acute bacterial prostatitis can be treated with ceftriaxone or gentamicin. Fluoroquinolones were the choice treatment for chronic bacterial prostatitis until recently; they are no longer recommended due to the increasing resistance and recent concerns regarding the safety of these drugs; alternative antibiotics such as fosfomycin are to be considered.

Consenso Argentino intersociedades de Infección Urinaria 2018-2019 - Parte II / Argentine Intersociety Consensus on Urinary Infection 2018-2019 - Part II

La segunda parte del Consenso Argentino Intersociedades de Infección Urinaria incluye el análisis de situaciones especiales. En pacientes con sonda vesical se debe solicitar urocultivo solo cuando hay signo-sintomatología de infección del tracto urinario, antes de instrumentaciones de la vía urinaria o como control en pacientes post-trasplante renal. El tratamiento empírico recomendado en pacientes sin factores de riesgo es cefalosporinas de tercera generación o aminoglucósidos. Las infecciones del tracto urinario asociadas a cálculos son siempre consideradas complicadas. En caso de obstrucción con urosepsis, deberá realizarse drenaje de urgencia por vía percutánea o ureteral. En pacientes con stents o prótesis ureterales, como catéteres doble J, el tratamiento empírico deberá basarse en la epidemiología, los antibióticos previos y el estado clínico. Antes del procedimiento de litotricia extracorpórea se recomienda pesquisar la bacteriuria y, si es positiva, administrar profilaxis antibiótica según el antibiograma. Cefalosporinas de primera generación o aminoglúcosidos son opciones válidas. Se recomienda aplicar profilaxis antibiótica con cefalosporinas de primera generación o aminoglúcosidos antes de la nefrolitotomía percutánea. La biopsia prostática trans-rectal puede asociarse a complicaciones infecciosas, como infecciones del tracto urinario o prostatitis aguda, principalmente por Escherichia coli u otras enterobacterias. En pacientes sin factores de riesgo para gérmenes multirresistentes y urocultivo negativo se recomienda realizar profilaxis con amikacina o ceftriaxona endovenosas. En pacientes con urocultivo positivo, se realizará profilaxis según antibiograma, 24 horas previas a 24 horas post-procedimiento. Para el tratamiento dirigido de la prostatitis post-biopsia trans-rectal, los carbapenémicos durante 3-4 semanas son el tratamiento de elección.

The second part of the Inter-Society Argentine Consensus on Urinary Tract Infection (UTI) includes the analysis of special situations. In patients with urinary catheter, urine culture should be requested only in the presence of UTI symptomatology, before instrumentation of the urinary tract, or as a post-transplant control. The antibiotics recommended for empirical treatment in patients without risk factors are third-generation cephalosporins or aminoglycosides. UTIs associated with stones are always considered complicated. In case of obstruction with urosepsis, an emergency drainage should be performed via a percutaneous nefrostomy or ureteral stenting. In patients with stents or ureteral prostheses, such as double J catheters, empirical treatment should be based on epidemiology, prior antibiotics, and clinical status. Before the extracorporeal lithotripsy procedure, bacteriuria should be investigated and antibiotic prophylaxis should be administered in case of positive result, according to the antibiogram. First generation cephalosporins or aminoglycosides are valid alternatives. The use of antibiotic prophylaxis with first-generation cephalosporins or aminoglycosides before percutaneous nephrolithotomy is recommended. Transrectal prostatic biopsy can be associated with infectious complications, such as UTI or acute prostatitis, mainly due to Escherichia coli or other enterobacteria. In patients without risk factors for multiresistant bacteria and negative urine culture, prophylaxis with intravenous amikacin or ceftriaxone is recommended. In patients with positive urine culture, prophylaxis will be performed according to the antibiogram, from 24 hours before to 24 hours post-procedure. For the targeted treatment of post-transrectal biopsy prostatitis, carbapenems for 3-4 weeks are the treatment of choice.

[Consenso Argentino Intersociedades de Infección Urinaria 2018-2019 - Parte I]. / Argentine Intersociety Consensus on Urinary Infection 2018-2019 - Part I.

The Argentine Society of Infectious Diseases and other scientific societies have updated these recommendations based on data on urinary tract infections in adults obtained from a prospective multicenter study conducted in Argentina during 2016-2017. Asymptomatic bacteriuria should be treated only in pregnant women, who should also be systematically investigated; the antibiotics of choice are nitrofurantoin, amoxicillin, clavulanic/amoxicillin, cephalexin and trimethoprim-sulfamethoxazole. In procedures involving injury to the urinary tract with bleeding, it is recommended to request urine culture and, in the presence of bacteriuria, antimicrobial treatment according to sensitivity should be prescribed from immediately before up to 24 hours after the intervention. In women, cystitis can be treated with nitrofurantoin, cephalexin or fosfomycin, while trimethoprim-sulfamethoxazole and fluoroquinolones are not recommended; pyelonephritis can be treated with ciprofloxacin, cefixime or cephalexin in ambulatory women or ceftriaxone, cefazolin or amikacin in those who are hospitalized. In men, urinary tract infections are always considered complicated; nitrofurantoin or cephalexin are recommended for 7 days, alternatively fosfomycin should be given in a single dose. In men, ciprofloxacin, ceftriaxone or cefixime are suggested for pyelonephritis on ambulatory treatment whereas ceftriaxone or amikacin are recommended for hospitalized patients. Acute bacterial prostatitis can be treated with ceftriaxone or gentamicin. Fluoroquinolones were the choice treatment for chronic bacterial prostatitis until recently; they are no longer recommended due to the increasing resistance and recent concerns regarding the safety of these drugs; alternative antibiotics such as fosfomycin are to be considered.

La Sociedad Argentina de Infectología y otras sociedades científicas han actualizado estas recomendaciones utilizando, además de información internacional, la de un estudio multicéntrico prospectivo sobre infecciones del tracto urinario del adulto realizado en Argentina durante 2016-2017. La bacteriuria asintomática debe ser tratada solo en embarazadas, a quienes también se las debe investigar sistemáticamente; los antibióticos de elección son nitrofurantoína, amoxicilina, amoxicilina-clavulánico, cefalexina y trimetoprimasulfametoxazol. Ante procedimientos que impliquen lesión con sangrado del tracto urinario se recomienda solicitar urocultivo para pesquisar bacteriuria asintomática, y, si resultara positivo, administrar antimicrobianos según sensibilidad desde inmediatamente antes hasta 24 horas luego de la intervención. En mujeres, la cistitis puede ser tratada con nitrofurantoina, cefalexina, o fosfomicina y no se recomienda usar trimetoprima-sulfametoxazol o fluoroquinolonas; en pielonefritis puede emplearse ciprofloxacina, cefixima o cefalexina si el tratamiento es ambulatorio o ceftriaxona, cefazolina o amikacina si es hospitalario. En los hombres, las infecciones del tracto urinario se consideran siempre complicadas. Se recomienda tratamiento con nitrofurantoina o cefalexina por 7 días, o bien monodosis con fosfomicina. Para la pielonefritis en hombres se sugiere ciprofloxacina, ceftriaxona o cefixima si el tratamiento es ambulatorio y ceftriaxona o amikacina si es hospitalario. Se sugiere tratar las prostatitis bacterianas agudas con ceftriaxona o gentamicina. En cuanto a las prostatitis bacterianas crónicas, si bien su tratamiento de elección hasta hace poco fueron las fluoroquinolonas, la creciente resistencia y ciertas dudas sobre la seguridad de estas drogas obligan a considerar el uso de alternativas como fosfomicina.

[Argentine Intersociety Consensus on Urinary Infection 2018-2019 - Part II]. / Consenso Argentino Intersociedades de Infección Urinaria 2018-2019 - Parte II.

The second part of the Inter-Society Argentine Consensus on Urinary Tract Infection (UTI) includes the analysis of special situations. In patients with urinary catheter, urine culture should be requested only in the presence of UTI symptomatology, before instrumentation of the urinary tract, or as a post-transplant control. The antibiotics recommended for empirical treatment in patients without risk factors are third-generation cephalosporins or aminoglycosides. UTIs associated with stones are always considered complicated. In case of obstruction with urosepsis, an emergency drainage should be performed via a percutaneous nefrostomy or ureteral stenting. In patients with stents or ureteral prostheses, such as double J catheters, empirical treatment should be based on epidemiology, prior antibiotics, and clinical status. Before the extracorporeal lithotripsy procedure, bacteriuria should be investigated and antibiotic prophylaxis should be administered in case of positive result, according to the antibiogram. First generation cephalosporins or aminoglycosides are valid alternatives. The use of antibiotic prophylaxis with first-generation cephalosporins or aminoglycosides before percutaneous nephrolithotomy is recommended. Transrectal prostatic biopsy can be associated with infectious complications, such as UTI or acute prostatitis, mainly due to Escherichia coli or other enterobacteria. In patients without risk factors for multiresistant bacteria and negative urine culture, prophylaxis with intravenous amikacin or ceftriaxone is recommended. In patients with positive urine culture, prophylaxis will be performed according to the antibiogram, from 24 hours before to 24 hours post-procedure. For the targeted treatment of post-transrectal biopsy prostatitis, carbapenems for 3-4 weeks are the treatment of choice.

La segunda parte del Consenso Argentino Intersociedades de Infección Urinaria incluye el análisis de situaciones especiales. En pacientes con sonda vesical se debe solicitar urocultivo solo cuando hay signo-sintomatología de infección del tracto urinario, antes de instrumentaciones de la vía urinaria o como control en pacientes post-trasplante renal. El tratamiento empírico recomendado en pacientes sin factores de riesgo es cefalosporinas de tercera generación o aminoglucósidos. Las infecciones del tracto urinario asociadas a cálculos son siempre consideradas complicadas. En caso de obstrucción con urosepsis, deberá realizarse drenaje de urgencia por vía percutánea o ureteral. En pacientes con stents o prótesis ureterales, como catéteres doble J, el tratamiento empírico deberá basarse en la epidemiología, los antibióticos previos y el estado clínico. Antes del procedimiento de litotricia extracorpórea se recomienda pesquisar la bacteriuria y, si es positiva, administrar profilaxis antibiótica según el antibiograma. Cefalosporinas de primera generación o aminoglúcosidos son opciones válidas. Se recomienda aplicar profilaxis antibiótica con cefalosporinas de primera generación o aminoglúcosidos antes de la nefrolitotomía percutánea. La biopsia prostática trans-rectal puede asociarse a complicaciones infecciosas, como infecciones del tracto urinario o prostatitis aguda, principalmente por Escherichia coli u otras enterobacterias. En pacientes sin factores de riesgo para gérmenes multirresistentes y urocultivo negativo se recomienda realizar profilaxis con amikacina o ceftriaxona endovenosas. En pacientes con urocultivo positivo, se realizará profilaxis según antibiograma, 24 horas previas a 24 horas post-procedimiento. Para el tratamiento dirigido de la prostatitis post-biopsia trans-rectal, los carbapenémicos durante 3-4 semanas son el tratamiento de elección.

Genetic Diversity of KPC-Producing Escherichia coli, Klebsiella oxytoca, Serratia marcescens, and Citrobacter freundii Isolates from Argentina.

The predominance of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae was caused by the spread of ST258 clone. In Latin America, KPC was reported in 2006, with the isolation of genetically unrelated K. pneumoniae in Colombia. Since then, the expansion of blaKPC in either K. pneumoniae ST258 or other Enterobacteriaceae (ETB) species was increasingly reported. In this study, we characterized 89 KPC-producing Escherichia coli, Klebsiella oxytoca, Serratia marcescens, and Citrobacter freundii that were received between 2010 and 2014. The results revealed that all isolates harbored blaKPC-2. Moreover, the dissemination of KPC by non-K. pneumoniae was mainly caused by the dispersion of ETB mostly genetically unrelated. E. coli is a community pathogen that may serve as the vehicle for the spread of KPC into community settings. Recently, KPC was detected in E. coli ST131, an international epidemic and multidrug-resistant clone. We found that 5/29 KPC-producing E. coli belonged to ST131 and four were blaCTXM-15 producers. The detection of blaKPC in ST131 should be closely monitored to prevent further dissemination. The blaKPC is generally located within Tn4401 transposon capable of mobilization through transposition found in plasmids in ST258. Less is known about the diversity of blaKPC genetic elements that disseminate horizontally among other species of ETB. We found that 16/29 E. coli and 2/18 S. marcescens harbored blaKPC-2 in Tn4401a. In 71 isolates, blaKPC-2 was located amidst diverse Tn3-derived genetic elements bearing non-Tn4401 structure. Further studies on the plasmids that encode blaKPC-2 in these clinical isolates may provide additional insight into its transmission mechanisms.

Prevalence of Plasmid-Mediated Quinolone Resistance Genes in Clinical Enterobacteria from Argentina.

This first nationwide study was conducted to analyze the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in phenotypically unselected (consecutive) clinical enterobacteria. We studied 1,058 isolates that had been consecutively collected in 66 hospitals of the WHONET-Argentina Resistance Surveillance Network. Overall, 26% of isolates were nonsusceptible to at least one of the three quinolones tested (nalidixic acid, ciprofloxacin, and levofloxacin). The overall prevalence of PMQR genes was 8.1% (4.6% for aac(6')-Ib-cr; 3.9% for qnr genes; and 0.4% for oqxA and oqxB, which were not previously reported in enterobacteria other than Klebsiella spp. from Argentina). The PMQR prevalence was highly variable among the enterobacterial species or when the different genes were considered. The prevalent PMQR genes were located in class 1 integrons [qnrB2, qnrB10, and aac(6')-Ib-cr]; in the ColE1-type plasmid pPAB19-1 or Tn2012-like transposons (qnrB19); and in Tn6238 or bracketed by IS26 and blaOXA-1 [aac(6')-Ib-cr]. The mutations associated with quinolone resistance that were located in the quinolone resistance-determining region (QRDR mutations) of gyrA, parC, and gyrB were also investigated. The occurrence of QRDR mutations was significantly associated with the presence of PMQR genes: At least one QRDR mutation was present in 82% of the PMQR-harboring isolates but in only 23% of those without PMQR genes (p < 0.0001, Fisher's Test). To the best of our knowledge, this is the first report on the prevalence of PMQR genes in consecutive clinical enterobacteria where all the genes currently known have been screened.

Molecular characterization of a clinical Haemophilus parainfluenzae isolate with cefotaxime resistance and decreased susceptibility to fluoroquinolones.

We report an H. parainfluenzae clinical isolate resistant to cefotaxime and with decreased susceptibility to ciprofloxacin recovered from a patient with cystic fibrosis. The isolate had elevated MICs of ampicillin (256mg/L), amoxicillin-clavulanate (8mg/L), cefuroxime (8mg/L) and cefotaxime (4mg/L), and showed a ß-lactamase-producing amoxicillin-clavulanic acid-resistant (BLPACR) phenotype. A blaTEM-1 plus five amino acid substitutions in the PBP3 were found: Ser385Thr, Val511Ala, Ile519Val, Asn526Lys and Asp551Leu. MIC of ciprofloxacin was 0.5mg/L, and substitutions in gyrA (Ser84Tyr) and parC (Ser84Phe) genes were detected.

New patterns of methicillin-resistant Staphylococcus aureus (MRSA) clones, community-associated MRSA genotypes behave like healthcare-associated MRSA genotypes within hospitals, Argentina.

Methicillin-resistant Staphylococcus aureus (MRSA) burden is increasing worldwide in hospitals [healthcare-associated (HA)-MRSA] and in communities [community-associated (CA)-MRSA]. However, the impact of CA-MRSA within hospitals remains limited, particularly in Latin America. A countrywide representative survey of S. aureus infections was performed in Argentina by analyzing 591 clinical isolates from 66 hospitals in a prospective cross-sectional, multicenter study (Nov-2009). This work involved healthcare-onset infections-(HAHO, >48 hospitalization hours) and community-onset (CO) infections [including both, infections (HACO) in patients with healthcare-associated risk-factors (HRFs) and infections (CACO) in those without HRFs]. MRSA strains were genetically typed as CA-MRSA and HA-MRSA genotypes (CA-MRSAG and HA-MRSAG) by SCCmec- and spa-typing, PFGE, MLST and virulence genes profile by PCR. Considering all isolates, 63% were from CO-infections and 55% were MRSA [39% CA-MRSAG and 16% HA-MRSAG]. A significantly higher MRSA proportion among CO- than HAHO-S. aureus infections was detected (58% vs 49%); mainly in children (62% vs 43%). The CA-MRSAG/HA-MRSAG have accounted for 16%/33% of HAHO-, 39%/13% of HACO- and 60.5%/0% of CACO-infections. Regarding the epidemiological associations identified in multivariate models for patients with healthcare-onset CA-MRSAG infections, CA-MRSAG behave like HA-MRSAG within hospitals but children were the highest risk group for healthcare-onset CA-MRSAG infections. Most CA-MRSAG belonged to two major clones: PFGE-type N-ST30-SCCmecIVc-t019-PVL(+) and PFGE-type I-ST5-IV-SCCmecIVa-t311-PVL(+) (45% each). The ST5-IV-PVL(+)/ST30-IV-PVL(+) clones have caused 31%/33% of all infections, 20%/4% of HAHO-, 43%/23% of HACO- and 35%/60% of CACO- infections, with significant differences by age groups (children/adults) and geographical regions. Importantly, an isolate belonging to USA300-0114-(ST8-SCCmecIVa-spat008-PVL(+)-ACME(+)) was detected for the first time in Argentina. Most of HA-MRSAG (66%) were related to the Cordobes/Chilean clone-(PFGE-type A-ST5-SCCmecI-t149) causing 18% of all infections (47% of HAHO- and 13% of HACO-infections). Results strongly suggest that the CA-MRSA clone ST5-IV-PVL(+) has begun to spread within hospitals, replacing the traditional Cordobes/Chilean-HA-MRSA clone ST5-I-PVL(-), mainly in children. Importantly, a growing MRSA reservoir in the community was associated with spreading of two CA-MRSA clones: ST5-IV-PVL(+), mainly in children with HRFs, and ST30-IV-PVL(+) in adults without HRFs. This is the first nationwide study in Argentina providing information about the molecular and clinical epidemiology of CA-MRSA, particularly within hospitals, which is essential for designing effective control measures in this country and worldwide.

Analysis of plasmid-mediated quinolone resistance genes in clinical isolates of the tribe Proteeae from Argentina: First report of qnrD in the Americas.

To analyse the occurrence and prevalence of plasmid-mediated quinolone resistance (PMQR) genes in the tribe Proteeae, 81 isolates (65 Proteus spp., 12 Morganella morganii and 4 Providencia stuartii) consecutively collected in 66 hospitals belonging to the WHONET-Argentina Resistance Surveillance Network were studied. Of the 81 isolates, 50 (62%) were susceptible to quinolones [43/65 (66%) Proteus spp. and 7/12 (58%) M. morganii). The remaining 31 isolates (22 Proteus spp., 5 M. morganii and all P. stuartii) showed high-level resistance to nalidixic acid (NAL) and decreased susceptibility or resistance to ciprofloxacin. All NAL-resistant isolates harboured mutations associated with quinolone resistance (MAQRs) in both gyrA (S83I/R) and parC (S80I/R), and some also had MAQRs in gyrB (S464Y/F). The unique PMQR gene detected was qnrD, which was found in 2/81 isolates (Proteus mirabilis Q1084 and Proteus vulgaris Q5169), giving a prevalence of 2.5% in Proteeae. These two isolates were from different geographical regions and both harboured MAQRs in gyrA and parC. The qnrD genes were located on the related plasmids pEAD1-1 (2683bp) and pEAD1-2 (2669bp). Plasmid pEAD1-1 was 100% identical to pCGH15 and differed in only three nucleotides from pDIJ09-518a, which were previously found in clinical isolates of P. mirabilis (China) and Providencia rettgeri (France), respectively, whilst pEAD1-2 was not previously described. The extended-spectrum ß-lactamase CTX-M-2 was found in 27% (22/81) of the isolates and was significantly associated with quinolone resistance but not with qnrD (only P. mirabilis Q1084 expressed CTX-M-2). This is the first report of qnrD in the Americas.