Characterization of an osteomyelitis case caused by dalbavancin, ceftaroline, and vancomycin non-susceptible methicillin-resistant Staphylococcus aureus.

We report a case of osteomyelitis due to methicillin-resistant Staphylococcus aureus (MRSA) that is also non-susceptible to vancomycin, dalbavancin, ceftaroline, and ceftobiprole, in the absence of exposure to the latter three antibiotics. It was isolated from a patient with a 26-year history of cranial surgeries and episodes of osteomyelitis. Whole-genome sequencing was performed. It was found to belong to ST247 and the mecA gene was detected within the SSCmec type I (1B) gene cassette that lacked the E447K mutation known to produce resistance to ceftobiprole and ceftaroline. However, mutations in other genes related to resistance to these antibiotics were found.

Risk factors for gentamicin-resistant E. coli in children with community-acquired urinary tract infection.

According to many guidelines, gentamicin is the empirical parenteral treatment for children with community-acquired urinary tract infection (CA-UTI). However, increasing resistance rates are reported. The purpose of this study is to analyze risk factors for presenting with a UTI caused by a community-acquired gentamicin-resistant Escherichia coli in children in our hospital and to describe their clinical outcome. A retrospective case-control local study was performed in a tertiary care hospital from January 2014 to December 2016. Cases and controls were children below 14 years old diagnosed in the Emergency Department with febrile CA-UTI caused by gentamicin-resistant and gentamicin-susceptible febrile E. coli strains, respectively. During the study period, 54 cases were included and compared with 98 controls. Patients with chronic conditions were more likely to present with a UTI due to gentamicin-resistant E. coli (OR 3.27; 95% CI 1.37-7.8, p < 0.05), as well as children receiving antibiotic prophylaxis (OR 3.5; 95% CI 1.2-10.1, p < 0.05). Cases had longer hospital stays than controls (5.8 ± 5 days vs. 4.4 ± 4 days, p = 0.017). Gentamicin-resistant strains associated higher rates of cefuroxime (29% vs. 3%), cefotaxime (27% vs. 0%), and quinolone resistance (40.7% vs. 6%) (p < 0.01) and produced more frequently extended-spectrum beta-lactamases (ESBL) (20% vs. 0%, p < 0.01) and carbapenemases (7.4% vs. 0%; p = 0.015). All gentamicin-resistant strains were amikacin-sensitive. The presence of chronic conditions and antibiotic prophylaxis could be potential risk factors for gentamicin-resistant E. coli CA-UTI in children. Simultaneous resistance to cephalosporins, quinolones, and ESBL/carbapenemase production is frequent in these strains.

Evaluating the optimal time for amikacin administration with respect to haemodialysis using an in vitro pharmacodynamic simulation against epidemic nosocomial OXA-48 producing Klebsiella pneumoniae ST405 strains.

OBJECTIVES: Bacterial viability and enrichment of resistance resulting from three different amikacin administration schedules with respect to haemodialysis (HD) were assessed against three OXA-48-producing Klebsiella pneumoniae isolated during an outbreak in a Spanish hospital. METHODS: A previously described two-compartment dynamic system was used. Three possible amikacin administration schedules were simulated: (i) haemodialysis immediately after amikacin infusion (pre-HD); (ii) infusion immediately after haemodialysis (post-HD); and (iii) infusion at 50% interdialytic period. Amikacin standard dose (SD) and double dose (DD) were simulated for each schedule. Values of Cmax/MIC, Cmax/MPC (mutant prevention concentration), AUC0-48h/MIC, AUC0-48h/MPC and %TMSW (percentage of time that the concentration was inside the mutant selection window) were determined with experimental data and were correlated with the area under the bacterial killing curve of the total population and the resistant subpopulation. RESULTS: Both with SD and DD, the pre-HD schedule resulted in increases at 48h in bacterial counts of the total population at the expense of enrichment of pre-existing resistant subpopulations from 12h onwards for all strains. The estimated %TMSW that prevented enrichment of resistant mutants was <61.5%. The AUC0-48h/MPC (with values of ≈40 being associated with countering of increases in resistant subpopulations) was better than the %TMSW as a predictive parameter. CONCLUSION: This study showed that the longest times concentrations were above the MPC (i.e. highest AUC0-48h/MPC, lowest %TMSW), the lowest enrichment of resistant subpopulations. This implies use of the highest possible amikacin dose (limited by toxicity) and post-HD as the best administration schedule.

Meropenem heteroresistance in clinical isolates of OXA-48-producing Klebsiella pneumoniae.

OXA-48-producing Klebsiellapneumoniae isolates often show growth of colonies within inhibition zones in carbapenem diffusion assays. The nature of these colonies was investigated in a series of clinical isolates of OXA-48-producing K. pneumoniae obtained in the context of a hospital outbreak, and they were found to be persistent colonies that reproduced again the same phenotype when they were collected and tested in diffusion assays again. The frequency of mutations conferring resistance to meropenem (8 µg/mL) was determined for the same isolates. The average mutation frequency was 5.47·10-6 (range: 2.59·10-8-5.87·10-5), and the analysis of several resistant mutants showed that all of them had mutations in the ompK36 porin gene. Heteroresistance was investigated using population analysis profiling. The profiles were compatible with mutation frequency assays, and all the colonies analyzed were resistant mutants. In OXA-48-producing K. pneumoniae, the growth of persisters seems to be specific of diffusion assays.

Genomic path to pandrug resistance in a clinical isolate of Klebsiella pneumoniae.

Carbapenem-resistant Klebsiella pneumoniae have spread globally throughout tertiary hospitals. Many Carbapenem-resistant K. pneumoniae clinical isolates are multidrug-resistant (MDR) and may become eventually pandrug-resistant (PDR). Here we present the closed genome of a PDR VIM-1-producing K. pneumoniae strain (KP1050) obtained in a tertiary hospital. The isolate belonged to sequence type 54 (ST54) and had five extrachromosomal elements (four plasmids and a circular phage genome). Most of the antimicrobial resistance genes (ARGs) were located in two clusters borne by two of the plasmids, comprising a class 1 integron that contained up to 14 ARGs including a VIM-1 metallo-ß-lactamase gene, and an IS26 transposon that contained a mobile element from Acinetobacter baumannii encoding the amikacin resistance gene aac(6')-Ian. A MDR isolate obtained 6 years previously was identified (KP1048) retrospectively and was sequenced. Comparison of the two genomes showed that chromosomal mutations in outer membrane porins as well as mutations in the ramR and phoQ genes contributed to increase the resistance spectrum.

Population structure of OXA-48-producing Klebsiella pneumoniae ST405 isolates during a hospital outbreak characterised by genomic typing.

OBJECTIVES: The aim of this study was to investigate the structure of a broad and sustained hospital outbreak of OXA-48-producing Klebsiella pneumoniae (KpO48) belonging to sequence type 405 (ST405). METHODS: Whole-genome sequencing and comparison of ten ST405 KpO48 isolates obtained from clinical samples in our hospital was performed. Using stringent criteria, 36 single nucleotide polymorphisms (SNPs) were detected (range 0-21 in pairwise comparisons), and allele-specific PCR was used to call the SNPs among a larger set of isolates. RESULTS: Several haplotypes were identified within the population. The haplotypes did not show a spatial structure, but a temporal evolution of sequential haplotype replacements was observed. CONCLUSIONS: The dispersed spatial distribution suggests a reservoir formed by a large pool of colonised patients, and the temporal replacement pattern suggests that the sustained outbreak was composed of several small outbreaks that appeared and rapidly dispersed to several units.

Activity of ceftazidime-avibactam against carbapenemase-producing Enterobacteriaceae from urine specimens obtained during the infection-carbapenem resistance evaluation surveillance trial (iCREST) in Spain.

The increasing rates of carbapenemase-producing Enterobacteriaceae (CPE) represent an important threat to health care systems and treatment of CPE infections is a challenge. The aim of the infection-carbapenem resistance evaluation surveillance trial (iCREST) was to determinate the prevalence of CPE in urine specimens in Spain and to evaluate the in vitro activity of ceftazidime-avibactam. Urine specimens (n = 11 826) were included and activity of ceftazidime-avibactam and comparators were investigated by broth microdilution in CPE. Carbapenemases were characterised by polymerase chain reaction (PCR) and sequencing as well as by whole genome sequencing (WGS). Overall prevalence of CPE was 1.6%. OXA-48 was the most prevalent (86.8%), followed by KPC (6.9%), VIM (4.8%), NDM (1.1%) and IMP (0.6%) carbapenemases. Klebsiella pneumoniae was the most common carbapenemase producer (87.8%). An uncommon carbapenemase type (IMP-8) in Spain was identify by WGS in an Enterobacter cloacae isolate, reinforcing the utility of surveillance programmes as effectives tools to detect unexpected genes that encode antimicrobial resistance. Ceftazidime-avibactam showed 100% susceptibility in KPC and OXA-48 producers and the rates of susceptibility in CPE non-susceptible to ceftazidime or meropenem were 92.1% and 96.9%, respectively. Ceftazidime-avibactam could be considered an adequate treatment option for urinary tract infections caused by KPC and OXA-48 producers.

Risk factors for colonization by carbapenemase-producing enterobacteria at admission to a Surgical ICU: A retrospective study / Factores de riesgo para la colonización por enterobacterias productoras de carbapenemasas en el momento de admisión en una UCI quirúrgica: estudio retrospectivo

Introduction: In 2011, a hospital-wide outbreak of OXA-48 producing Klebsiella pneumoniae occurred in our hospital, an epidemiological setting of high ESBL-producing K. pneumoniae rates. This study identifies risk factors for colonization with carbapenemase-producing enterobacteria (CPE) at Surgical Intensive Care Unit (SICU) admission. Methods: A 2-year retrospective study was performed in all patients admitted to the SICU that following routine had a rectal swab collected upon admission. Results: Of 254 patients admitted, 41 (16.1%) harbored CPE (five showing two carbapenemase-producing isolates). Most frequent carbapenemase-producing isolates and carbapenemases were K. pneumoniae (39/46, 84.8%) and OXA-48 (31/46; 76.1%), respectively. Carriers significantly had higher rates of chronic renal disease, previous digestive/biliary endoscopy, hospitalization, ICU/SICU admission, intraabdominal surgery, and antibiotic intake, as well as higher median values of clinical scores (SOFA, SAPS II and APACHE II). In the multivariate analysis (R2 = 0.309, p < 0.001), CPE carriage was associated with prior administration of 3rd-4th generation cephalosporins (OR = 27.96, 95%CI = 6.88, 113.58, p < 0.001), β -lactam/ β -lactamase inhibitor (OR = 11.71, 95%CI = 4.51, 30.43, p < 0.001), abdominal surgery (OR = 6.33, 95%CI = 2.12, 18.89, p = 0.001), and prior digestive/biliary endoscopy (OR = 3.88, 95%CI = 1.56, 9.67, p = 0.004). Conclusions: A strong association between production of ESBLs and carriage of CPE (mainly OXA-48 producing K. pneumoniae) was found. According to the model, the co-selection of β-lactamases by previous exposure to broad-spectrum cephalosporins and β-lactam/ β -lactamase inhibitors (with lower relative risk), abdominal surgery and prior digestive/biliary endoscopy were factors associated with CPE carriage (AU)

Introducción: En 2011 se produjo un brote epidémico de Klebsiella pneumoniae productor de OXA-48 en nuestro hospital, un entorno epidemiológico de altas tasas de K. pneumoniae productor de BLEE. Este estudio identifica factores de riesgo de colonización por enterobacterias productoras de carbapenemasas (EPC) en el momento del ingreso en la unidad de cuidados críticos quirúrgicos (UCCQ). Métodos: Se realizó un estudio retrospectivo durante 2 años en todos los pacientes ingresados en la UCCQ a los que, siguiendo la rutina habitual, se les tomaba un hisopo rectal en el momento de ingreso. Resultados: De los 254 pacientes ingresados, 41 (16,1%) portaban EPC (5 con 2 aislados productores de carbapenemasas). Los aislados productores de carbapenemasas y las carbapenemasas más frecuentes fueron K. pneumoniae (39/46, 84,8%) y OXA-48 (31/46; 76,1%), respectivamente. Los portadores presentaban de forma significativa mayor frecuencia de insuficiencia renal crónica, historia previa de endoscopia digestiva/biliar, hospitalización, ingreso previo en UCI/UCCQ, cirugía intraabdominal y exposición a antibióticos, así como valores más altos (mediana) de SOFA, SAPS II y APACHE II. En el análisis multivariado (R2 = 0,309; p < 0,001), el estado de portador de EPC se asoció con la administración previa de cefalosporinas de amplio espectro (OR = 27,96; IC 95%: 6,88-113,58; p < 0,001), β-lactámicos/inhibidores de β -lactamasas (OR = 11,71; IC 95%: 4,51-30,43; p < 0,001), cirugía abdominal (OR = 6,33; IC 95%: 2,12- 18,89; p = 0,001) y endoscopia digestiva/biliar previa (OR = 3,88; IC 95%: 1,56-9,67; p = 0,004). Conclusiones: Se encontró una fuerte asociación entre la producción de BLEE y la portación de EPC (fundamentalmente K. pneumoniae productora de OXA-48). De acuerdo con el modelo, la co-selección de β-lactamasas tras exposición previa a cefalosporinas de amplio espectro y en menor medida a β-lactámicos/inhibidores de β-lactamasas, la cirugía abdominal y la endoscopia digestiva/biliar previa fueron factores asociados a la portación de EPC (AU)

A novel mutation in pmrB mediates colistin resistance during therapy of Acinetobacter baumannii.

Acinetobacter baumannii is a highly versatile nosocomial pathogen. Multidrug resistance among A. baumannii isolates led to the use of colistin, subsequently giving rise to colistin-resistant strains. In this study, the genetic and phenotypic profiles of two colistin-resistant A. baumannii isolates were investigated. Two A. baumannii isolates were obtained from Patient 1 (C071 and C440) and three isolates were obtained from Patient 2 (C080, C314 and C428). Susceptibility profiles were determined by VITEK®2 and Etest. Clonality was determined by RAPD analysis and trilocus multiplex PCR. The pmrCAB operon was sequenced and common carbapenemase genes were screened for by PCR. Doubling times, haemolysis, surface motility, biofilm formation, siderophore production and proteolytic activity were phenotypically determined. Finally, whole-genome sequencing was performed for all five isolates. Isolates C440 and C428 were resistant to colistin and were clonally identical to their sensitive counterparts. The cause of colistin resistance was traced to the previously described P233S mutation in pmrB of C440 and to a novel ΔI19 mutation in pmrB of C428. blaOXA-58-like and blaGES-5 from the strains of Patients 1 and 2, respectively, were also detected. C440 had attenuated proteolytic activity and was positive for siderophore production compared with C071. No difference in in vitro virulence was detected between isolates C080, C314 and C428. In conclusion, one common and one novel mutation were encountered in pmrB from two distinct colistin-resistant A. baumannii isolates. These mutations caused colistin resistance during therapy in two distinct clones, and only one of them had altered in vitro virulence.

Clonality, virulence determinants, and profiles of resistance of clinical Acinetobacter baumannii isolates obtained from a Spanish hospital.

INTRODUCTION: Acinetobacter baumannii is a nosocomial pathogen that is showing increasing rates of carbapenem resistance. Multi-Drug Resistant (MDR) International Clones (ICs), associated with certain oxacillinases, are being reported globally. This organism also harbors numerous virulence determinants. In this study, we aim at characterizing A. baumannii isolated from a Spanish hospital in terms of antimicrobial susceptibility, clonality, carbapenemase genes harbored, and virulence determinants expressed. MATERIALS AND METHODS: Fifty nine clinical bloodstream isolates were obtained from 2009 until 2013. Antimicrobial Susceptibility Testing was performed according to the CLSI guidelines. PFGE and tri-locus PCR typing were then performed in order to determine local and international clonality. PCRs for the detection of common carbapenemases were also performed. Production of hemolysis, biofilms, siderophores, surface motility, and proteolysis were determined phenotypically. Doubling times for selected strains were also calculated. Finally, statistical analysis for detecting associations between these factors was conducted. RESULTS AND DISCUSSION: Carbapenem non-susceptibility was 84.75%, suggesting the immediate need for intervention. PFGE showed the distribution of the majority of the isolates among 7 clusters. Although all three ICs were detected, IC II was predominant at 71.19%. blaOXA-24-like was the most prevalent carbapenemase (62.71%), followed by blaOXA-58-like (13.56%), and blaOXA-23-like (11.86%). Strains pertaining to IC II, and those harboring blaOXA-24-like, were positively associated with α-hemolysis, production of strong biofilms, and siderophore production. Harboring blaOXA-23-like and blaOXA-58-like was associated with attenuated virulence. These associations suggest that an interplay exists between these factors that could be locally exploited. CONCLUSIONS: An alarmingly high rate of carbapenem non-susceptibility has been detected in this study. There was a predominance of IC II and blaOXA-24-like, and those factors were associated with heightened expression of virulence determinants. This association could be exploited for modifying treatment regimens and for improving on infection control protocols in this hospital.

Risk factors for colonization by carbapenemase-producing enterobacteria at admission to a Surgical ICU: A retrospective study.

INTRODUCTION: In 2011, a hospital-wide outbreak of OXA-48 producing Klebsiella pneumoniae occurred in our hospital, an epidemiological setting of high ESBL-producing K. pneumoniae rates. This study identifies risk factors for colonization with carbapenemase-producing enterobacteria (CPE) at Surgical Intensive Care Unit (SICU) admission. METHODS: A 2-year retrospective study was performed in all patients admitted to the SICU that following routine had a rectal swab collected upon admission. RESULTS: Of 254 patients admitted, 41 (16.1%) harbored CPE (five showing two carbapenemase-producing isolates). Most frequent carbapenemase-producing isolates and carbapenemases were K. pneumoniae (39/46, 84.8%) and OXA-48 (31/46; 76.1%), respectively. Carriers significantly had higher rates of chronic renal disease, previous digestive/biliary endoscopy, hospitalization, ICU/SICU admission, intraabdominal surgery, and antibiotic intake, as well as higher median values of clinical scores (SOFA, SAPS II and APACHE II). In the multivariate analysis (R2=0.309, p<0.001), CPE carriage was associated with prior administration of 3rd-4th generation cephalosporins (OR=27.96, 95%CI=6.88, 113.58, p<0.001), ß-lactam/ß-lactamase inhibitor (OR=11.71, 95%CI=4.51, 30.43, p<0.001), abdominal surgery (OR=6.33, 95%CI=2.12, 18.89, p=0.001), and prior digestive/biliary endoscopy (OR=3.88, 95%CI=1.56, 9.67, p=0.004). CONCLUSIONS: A strong association between production of ESBLs and carriage of CPE (mainly OXA-48 producing K. pneumoniae) was found. According to the model, the co-selection of ß-lactamases by previous exposure to broad-spectrum cephalosporins and ß-lactam/ß-lactamase inhibitors (with lower relative risk), abdominal surgery and prior digestive/biliary endoscopy were factors associated with CPE carriage.

Evaluation of combined use of the MALDI-TOF and GenomEra MRSA/SA assay for the direct detection of methicillin resistance in Staphylococcus aureus from positive blood culture bottles / Evaluación del uso combinado de ensayo de MALDI-TOF y Genomera MRSA/SA para la detección directa de la resistencia a la meticilina en Staphylococcus aureus de botellas de hemocultivo positivo

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Community-Onset Bloodstream and Other Infections, Caused by Carbapenemase-Producing Enterobacteriaceae: Epidemiological, Microbiological, and Clinical Features.

Background. Because most infections caused by carbapenemase-producing Enterobacteriaceae (CPE) begin during hospitalization, there are limited data about community-onset (CO) infections caused by CPE. Our aim is to describe the frequency of CO infections caused by CPE as well as the clinical features of CO bloodstream infections (CO-BSIs). Methods. This study includes retrospective case series of CO infections caused by CPE in a tertiary hospital from January 2010 to July 2014. Any clinical sample with a positive culture for CPE that had been ordered by primary care doctors or by doctors at the emergency room (ER) were classified as CO. Epidemiological and microbiological features of CO cases were assessed as were clinical features of CO-BSIs. Results. Of 780 clinical samples with CPE, 180 were requested at the ER or by primary care doctors (22.9%), 150 of which were produced by Klebsiella pneumoniae (83.3%). The blaOXA-48 gene was detected in 149 isolates (82.8%) followed by the blaVIM gene, 29 (16.1%). Sixty-one patients (33.9%) had a prior history of CPE infection/colonization. Thirty-four of the 119 (28.6%) patients without prior history of CPE infection/colonization did not fulfill Friedman criteria for healthcare-associated infections (HAIs). Considering previous hospitalization of up to 12 months as a criterion for defining HAI, only 16 (13.4%) cases were identified as community-acquired infections. The most frequent positive sample was urine (133 of 180; 73.9%). Twenty-one (11.7%) patients had a BSI, 9 of them secondary to urinary tract infections (42.9%). Thirty-day crude mortality among patients with BSI was 23.8% (5 of 21). Conclusions. Community-onset infections caused by CPE are an important subgroup of all CPE infections. The urinary tract is the main source. Bloodstream infections accounted for more than 10% of the cases.

Development of daptomycin resistance during therapy in a patient with methicillin-resistant Staphylococcus aureus endocarditis: a case report / Desarrollo de resistencia a daptomicina durante el tratamiento de un paciente con endocarditis por Staphylococcus aureus resistente a meticilina

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