[Molecular characterization of Listeria monocytogenes isolates from human and food sources in Argentina, 2018-2023]. / Caracterización molecular de aislamientos de Listeria monocytogenes de origen humano y alimentario en Argentina, 2018-2023.

Human listeriosis is an infectious disease caused by Listeria monocytogenes. The invasive form of this disease leads to a high rate of hospitalizations and fatality. The main mode of transmission is through contaminated ready-to-eat foods such as dairy, vegetables and meat products. The knowledge of the diversity and population dynamics of isolates collected from human and food sources is essential for the detection of clusters and the identification of common sites of infection. The aim of this study was the molecular characterization of L. monocytogenes isolates in Argentina. We sequenced a total of 63 isolates, 35 from human and 28 from food sources, collected between 2018 and 2023. Our genomic study divided the isolates into two lineages, four serogroups, 17 sequence types and 15 clonal complexes (CCs). The hypervirulent clone CC1 (lineage I; serogroup IVb) predominated in human and food samples. The phylogenomic analysis showed a high and possible epidemiological relationship between isolates from human and/or food sources, suggesting the presence of transmission chains in our country. These findings highlight the need to strengthen genomic surveillance of L. monocytogenes in Argentina. The identification of geographic distribution and characteristics of predominant and emerging clones from human and food sources might help to focus action plans and public health policies better directed at the control and prevention of listeriosis.

Study of the genetic diversity of Moraxella spp. isolates obtained from corneal abscesses.

This is the first study of the genetic diversity of Moraxella spp. Isolates were detected in an Eye Hospital in the City of Buenos Aires. Due to the high frequency of Moraxella spp. observed in corneal abscesses, we decided to validate their identification at the species level, determine their drug susceptibility and perform molecular subtyping. Seventeen (17) isolates obtained from corneal abscesses were evaluated. The identification was carried out using a combination of biochemical tests and MALDI-TOF mass spectrometry. Of these isolates, 88.2% were identified as Moraxella lacunata, and 11.8% as Moraxella nonliquefaciens. Molecular subtyping was performed using the pulsed-field gel electrophoresis (PFGE) technique. All isolates were typable and thirteen digestion patterns were identified. Based on the obtained results, the PFGE technique using the SmaI enzyme can be used for epidemiological studies of strains of these species.

[Legionnaires' disease in Argentina: Evolution of the laboratory diagnostic strategy]. / Enfermedad del legionario en Argentina: evolución de la estrategia diagnóstica en el laboratorio.

Legionnaires' disease (LD) is severe acute pneumonia that occurs in sporadic or epidemic form, and generally requires hospitalization. The objective of this work was to describe the experience in the LD laboratory diagnostic approach in Argentina during the period 2016-2021. The laboratory analyzed 168 clinical specimens from 93 cases of suspected LD pneumonia. Laboratory tests included the detection of the soluble antigen of Legionella pneumophila serogroup 1 in urine sample, detection of DNA of Legionella spp. in lower respiratory secretions by conventional and commercial molecular methods and isolation in selective medium. LD was confirmed in 12 patients. The urinary antigen allowed the diagnosis for 8 patients. L. pneumophila was isolated from the respiratory material of 6 patients suffering from health care-associated pneumonia, who had been previously diagnosed using the commercial molecular method. Fifty percent of these cases did not show detectable urinary antigen. A single patient did not shows neither detectable antigenuria nor isolation of Legionella from the respiratory sample and was diagnosed as a confirmed case of LD by the detection of DNA of Legionella spp. by PCR directly from the respiratory secretion and the epidemiological link with another case of confirmed LD by culture. Urinary antigen detection is the first-line diagnostic test. However, the incorporation of complementary molecular methods has proved to avoid false negatives and contributed to a better understanding of the true incidence of the disease.

[Dolosigranulum pigrum in corneal abscess]. / Dolosigranulum pigrum en absceso corneal.

Dolosigranulum pigrum is a gram-positive, facultatively anaerobic coccus, which is part of the oral and upper respiratory tract microbiota. Although reports of infections by this microorganism are scarce, it has been associated with a wide spectrum of infectious diseases. The case of an elderly man with a lower corneal abscess, in which Dolosigranulum pigrum was isolated, is described. The microorganism was identified by mass spectrometry (MALDI-TOF MS) and by the sequencing of the 16S rRNA gene. Furthermore, the presumptive identification of the causative agent was achieved by using key phenotypic tests such as the cluster arrangement in Gram stain, the negative catalase test, the production of pyrrolidonyl arylamidase and leucine aminopeptidase activity, the growth in 6.5% NaCl and esculin hydrolysis. The data from the literature (and the present case) support the association of the microorganism with ocular infections, which often take a destructive course, mainly in elderly patients.

SARS-CoV-2 and Chlamydia pneumoniae co-infection: A review of the literature.

Bacterial co-pathogens are commonly identified in viral respiratory infections and are important causes of morbid-mortality. The prevalence of Chlamydia (C.) pneumoniae infection in patients infected with SARS-CoV-2 has not been sufficiently studied. The objective of the present review was to describe the prevalence of C. pneumoniae in patients with coronavirus disease 2019 (COVID-19). A search in MEDLINE and Google Scholar databases for English language literature published between January 2020 and August 2021 was performed. Studies evaluating patients with confirmed COVID-19 and reporting the simultaneous detection of C. pneumoniae were included. Eleven articles were included in the systematic review (5 case cross-sectional studies and 6 retrospective studies). A total of 18450 patients were included in the eleven studies. The detection of laboratory-confirmed C. pneumoniae infection varied between 1.78 and 71.4% of the total number of co-infections. The median age of patients ranged from 35 to 71 years old and 65% were male. Most of the studies reported one or more pre-existing comorbidities and the majority of the patients presented with fever, cough and dyspnea. Lymphopenia and eosinopenia were described in COVID-19 co-infected patients. The main chest CT scan showed a ground glass density shadow, consolidation and bilateral pneumonia. Most patients received empirical antibiotics. Bacterial co-infection was not associated with increased ICU admission and mortality. Despite frequent prescription of broad-spectrum empirical antimicrobials in patients with coronavirus 2-associated respiratory infections, there is a paucity of data to support the association with respiratory bacterial co-infection. Prospective evidence generation to support the development of an antimicrobial policy and appropriate stewardship interventions specific for the COVID-19 pandemic are urgently required.

[Evolution of the performance of Latin America Reference Laboratories in the detection of mechanisms of antimicrobial resistanceEvolução do desempenho dos Laboratórios de Referência na América Latina na detecção de mecanismos de resistência antimicrobiana]. / Evolución del desempeño de Laboratorios de Referencia de América Latina en la detección de mecanismos de resistencia a los antimicrobianos.

OBJECTIVE: The objective is to present the results of the Latin American Program for Quality Assurance in Bacteriology and Antimicrobial Resistance (LA-EQAS) between 2000 and 2018 and the evolution of the detection of resistance mechanisms with clinical impact. METHODS: The participating National Reference Laboratories (NRLs) received 25 surveys with 10 strains in each one, representing a total of 86 bacterial species and 40 resistance mechanisms. To evaluate the performance of the NRLs, five indicators were analyzed: bacterial identification, interpretation of susceptibility testing, acceptable ranges for zones of inhibition, inferred resistance mechanism, and delay time for the response. RESULTS: The average concordance was 82.6% (range: 74-95%) for bacterial identification, 93.3% (85-98%) for the interpretation of susceptibility testing, 84.6% (70-94%) for the zones of inhibition, and 82.5% (73-96%) for the inferred resistance mechanisms. The average delay time for the response was 34 days. Improvements in the detection of mechanisms of clinical importance, such as resistance to methicillin, macrolides and glycopeptides in Gram-positive cocci, and extended-spectrum, AmpC plasmid and carbapenemase beta-lactamases in Gram-negative bacilli, were observed. CONCLUSIONS: The LA-EQAS is an excellent tool for continuous quality improvement in the diagnosis of infections due to multiresistant microorganisms in NRLs in Latin America.

OBJETIVO: O objetivo deste trabalho é apresentar os resultados do Programa Latino-Americano de Garantia da Qualidade em Bacteriologia e Resistência Antimicrobiana (LA-EQAS, na sigla em inglês) entre 2000 e 2018 e a evolução na detecção de mecanismos de resistência com impacto clínico. MÉTODOS: Os Laboratórios Nacionais de Referência (LNRs) participantes receberam 25 inquéritos com 10 cepas bacterianas cada, representando um total de 86 espécies bacterianas e 40 mecanismos de resistência. Para avaliar o desempenho dos LNRs, foram analisados cinco indicadores: identificação bacteriana, interpretação dos testes de sensibilidade, faixas das zonas de inibição aceitáveis, mecanismo de resistência inferido e tempo de demora na resposta. RESULTADOS: A concordância média foi de 82,6% (intervalo: 74-95%) na identificação bacteriana, 93,3% (85-98%) na interpretação dos testes de sensibilidade, 84,6% (70-94%) nas zonas de inibição, 82,5% (73-96%) no mecanismo de resistência inferido e 34 dias na demora na resposta. Observou-se uma melhoria na detecção de mecanismos clinicamente relevantes, como a resistência a meticilina, macrolídeos e glicopeptídeos em cocos Gram-positivos, beta-lactamases de espectro ampliado, AmpC plasmídica e carbapenemases em bacilos Gram-negativos. CONCLUSÕES: O LA-EQAS é uma excelente ferramenta para a melhoria contínua da qualidade no diagnóstico de infecções por microrganismos multirresistentes nos LNRs da América Latina.

[Development and evaluation of an in-house database for quick identification of Burkholderia contaminans by MALDI-TOF MS]. / Desarrollo y evaluación de una base de datos in house para la identificación rápida de Burkholderia contaminans por EM MALDI-TOF.

MALDI-TOF (matrix assisted laser desorption ionization-time of flight) mass spectrometry (MS) proved to be a robust tool for the identification of numerous taxonomic groups. However, it has limitations. A key advantage of this technique is the flexibility for the incorporation of protein profiles of microorganisms not included in the commercial database. Due to the prevalence of Burkholderia contaminans in fibrocystic patients in Argentina and the fact that rapid and reliable microbiological diagnosis is crucial in them, MALDI-TOF MS emerges as a strategic tool. The aim of this work was to develop an additional database with peptide spectra of reference isolates of B. contaminans. This database demonstrated to be successful for the identification of 97% of the isolates analyzed. Therefore, MALDI-TOF MS with the extended database was a useful tool for the identification and differentiation of other related species to B. contaminans.

[Mycoplasma hominis bacteremia. An underestimated etiological agent]. / Bacteriemia por Mycoplasma hominis: un agente etiológico subestimado.

Mycoplasma hominis is a fastidious bacterium, which usually colonizes the lower urogenital tract and may cause systemic infections in neonates and genital infections in adults. It can also be the cause of serious extra-genital infections, mainly in immunosuppressed or predisposed subjects. CASE PRESENTATION: We describe a case of bacteremia caused by M. hominis in a previously healthy woman after uterine curettage due to incomplete abortion. M. hominis could be an underestimated cause of bacteremia in immunocompetent patients. Mycoplasma organisms have fastidious growth requirements, are often difficult to culture on a cell-free medium and have no cell wall. The conventional method for detection may fail. This is the first report of M. hominis isolation from a positive automated blood culture (BD BACTEC, USA).

[Bartonella henselae: Serological evidence in pediatric patients with clinical suspicion of cat scratch disease]. / Bartonella henselae: evidencia serológica en pacientes pediátricos con sospecha clínica de enfermedad por arañazo de gato.

Cat scratch disease (CSD) is caused by Bartonella henselae, which mainly affects children. The cat is the reservoir. The laboratory diagnosis is based on the detection of antibodies by the Indirect Immunofluorescence (IFI) assay. The objective of this study was to analyze the serological evidence of B. henselae infection in pediatric patients that met the clinical/epidemiological criteria for suspected CSD. We studied 92 patients, who were categorized into four serological groups: 1) IgG (+)/IgM(+), 31,5% (n=29); 2) IgG (-)/IgM(+), 10,9% (n=10); 3) IgG (+)/IgM(-), 9,8% (n=9); 4) IgG (-)/IgM(-), 47,8% (n=44). These findings aim to promote future works for investigating the seroprevalence of Bartonella spp. in Argentina, which will allow us to know the importance of this zoonosis in our population and to evaluate new cut-off points of the technique.

Antibiotic susceptibility of Listeria monocytogenes in Argentina.

INTRODUCTION: Listeria monocytogenes is the causative agent of listeriosis, a food-borne disease that mainly affects pregnant women, the elderly, and immunocompromised patients. The primary treatment of choice of listeriosis is the combination of ampicillin or penicillin G, with an aminoglycoside, classically gentamicin. The second-choice therapy for patients allergic to ß-lactams is the combination of trimethoprim with a sulfonamide (such as co-trimoxazole). The aim of this study was to analyze the antimicrobial susceptibility profile of strains isolated from human infections and food during the last two decades in Argentina. METHODS: The minimal inhibitory concentration (MIC) of 8 antimicrobial agents was determined for a set of 250 strains of L. monocytogenes isolated in Argentina during the period 1992-2012. Food-borne and human isolates were included in this study. The antibiotics tested were ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, erythromycin, gentamicin, penicillin G, tetracycline and rifampicin. Breakpoints for penicillin G, ampicillin and trimethoprim-sulfamethoxazole were those given in the CLSI for L. monocytogenes. CLSI criteria for staphylococci were applied to the other antimicrobial agents tested. Strains were serotyped by PCR, and confirmed by an agglutination method. RESULTS: Strains recovered from human listeriosis patients showed a prevalence of serotype 4b (71%), with the remaining 29% corresponding to serotype 1/2b. Serotypes among food isolates were distributed as 62% serotype 1/2b and 38% serotype 4b. All antimicrobial agents showed good activity. CONCLUSION: The strains of L. monocytogenes isolated in Argentina over a period of 20 years remain susceptible to antimicrobial agents, and that susceptibility pattern has not changed during this period.

The Genetic relatedness of Burkholderia contaminans clinical isolates from cystic fibrosis and non-cystic fibrosis patients in Argentina.

INTRODUCTION: The Burkholderia cepacia complex (BCC) bacteria are opportunistic pathogens that cause nosocomial infections and are especially dangerous for cystic fibrosis (CF) patients. Burkholderia contaminans is an emerging BCC species isolated from CF patients that also occurs as a contaminant in pharmaceutical and personal care products, sometimes linking it with outbreaks. METHODOLOGY: A total of 55 B. contaminans isolates from CF and non-CF patients in Argentina were identified by recA sequencing and MALDI TOF MS. A standardized Pulsed Field Gel Electrophoresis (PFGE) protocol was set up in order to assess genetic diversity, outbreak investigations, and possible clone persistence. RESULTS: All isolates were identified as B. contaminans by both MALDI-TOF MS and recA sequence analysis. PFGE has enabled us to compare and determine the genetic relationship between B. contaminans isolates. Isolates were distributed in different PFGE clusters with evidence of the presence and persistence of a clone, over a period of 3 years, in the same hospital. This large hospital outbreak involved CF and non-CF patients. Moreover, PFGE results showed a good correlation between sporadic or outbreak-related isolates and the available epidemiological information. CONCLUSIONS: These findings highlight the importance of B. contaminans in Argentina and provide evidence for encouraging the surveillance of highly transmissible clones. The study also contributes to global knowledge about B. contaminans infections.

Exploring the value of MALDI-TOF MS for the detection of clonal outbreaks of Burkholderia contaminans.

BACKGROUND: Molecular genetics has risen in both output and affordability to become the gold standard in diagnosis, however it is not yet available for most routine clinical microbiology due to cost and the level of skill it requires. Matrix assisted laser desorption/ionisation - time of flight mass spectrometry (MALDI-TOF MS) approaches may be useful in bridging the gap between low-resolution phenotypic methods and bulky genotypic methods in the goal of epidemiological source-typing of microbes. Burkholderia has been shown to be identifiable at the subspecies level using MALDI-TOF MS. There have not yet been studies assessing the ability of MALDI-TOF MS to source-type Burkholderia contaminans isolates into epidemiologically relevant outbreak clusters. METHODS: 55 well-characterised B. contaminans isolates were used to create a panel for analysis of MALDI-TOF MS biomarker peaks and their relation to outbreak strains, location, source, patient, diagnosis and isolate genetics. Unsupervised clustering was performed and classification models were generated using biostatistical analysis software. RESULTS: B. contaminans spectra derived from MALDI-TOF MS were of sufficiently high resolution to identify 100% of isolates. Unsupervised clustering methods showed poor evidence of spectra clustering by all characteristics measured. Classification algorithms were discriminatory, with Genetic Algorithm models showing 100% recognition capability for all outbreaks, the pulsed-field gel electrophoresis (PFGE) typeability model, and 96.63% recognition for the location model. A consistent peak at m/z of approximately 6943 was identified in all non-typeable strains but in none of the typeable strains. CONCLUSIONS: MALDI-TOF MS successfully discriminates B. contaminans isolates into clonal, epidemiological clusters, and can recognise isolates non-typeable by PFGE. Further work should investigate this capability, and include peptide studies and genomic sequencing to identify individual proteins or genes responsible for this non-typeablity, particularly at the peak weight identified.

Study of the genetic diversity of Moraxella spp. isolates obtained from corneal abscesses / Estudio de la diversidad genética de aislamientos de Moraxella spp. a partir de abscesos corneales

Abstract This is the first study of the genetic diversity of Moraxella spp. Isolates were detected in an Eye Hospital in the City of Buenos Aires. Due to the high frequency of Moraxella spp. observed in corneal abscesses, we decided to validate their identification at the species level, determine their drug susceptibility and perform molecular subtyping. Seventeen (17) isolates obtained from corneal abscesses were evaluated. The identification was carried out using a combination of biochemical tests and MALDI-TOF mass spectrometry. Of these isolates, 88.2% were identified as Moraxella lacunata, and 11.8% as Moraxella nonliquefaciens. Molecular subtyping was performed using the pulsed-field gel electrophoresis (PFGE) technique. All isolates were typable and thirteen digestion patterns were identified. Based on the obtained results, the PFGE technique using the SmaI enzyme can be used for epidemiological studies of strains of these species.

Resumen En este trabajo se presenta el primer estudio de diversidad genética de aislamientos de Moraxella spp. detectados en un hospital de oftalmología de la Ciudad Autónoma de Buenos Aires. Debido a la observación de una elevada frecuencia de Moraxella spp. en abscesos corneales, se decidió confirmar su identificación a nivel de especie, conocer su sensibilidad y realizar la subtipificación molecular. Se analizaron 17 aislamientos provenientes de abscesos corneales. La identificación se realizó mediante una combinación de pruebas bioquímicas y espectrometría de masas, MALDI-TOF MS. El 88,2% fueron identificados como Moraxella lacunata y el 11,8% como Moraxella nonliquefaciens. La subtipificación molecular se realizó por la técnica de electroforesis en gel de campo pulsado (PFGE). Todos los aislamientos fueron tipificables y se identificaron 13 patrones de digestión. Nuestros resultados muestran que la técnica de PFGE con la enzima SmaI es útil para hacer estudios epidemiológicos en cepas de estas especies.

Sepsis secondary to complicated skin and soft tissue infection caused by Ignatzschineria indica. First case report in Latin America.

INTRODUCTION: Ignatzschineria is a recently recognized genus associated with larvae infestation Members of this genus are pathogens infrequently implicated in human disease. During the last decade, fewer than 10 cases of infection with Ignatzchineria species have been reported around the world. Bacteria of the genera Ignatzchineria and Wohlfahrtiimonas have been isolated from larvae of the parasitic fly Wohlfahrtia magnifica, which is found in Europe, Asia and North Africa, and is associated with myiasis in several animal species, but rarely in humans. CASE PRESENTATION: We report the first case of sepsis associated with complicated skin and soft tissue infection caused by I. indica in Latin America. CONCLUSION: The clinical and molecular findings in our report add information to the accumulating data on emerging pathogens of this type, their geographic distribution, the correlation between the emergence of infectious diseases and social and economic inequalities, as well as the effects of global climate changes on potentially unusual distribution of vectors. We consider that fly larvae should be regarded as a potential source of specific arthropod-borne bacterial systemic infections.

Prevalence of Burkholderia cepacia complex species in cystic fibrosis patients in Argentina during the period 2011-2015. / Prevalencia de especies del complejo Burkholderia cepacia en pacientes con fibrosis quística en Argentina durante el período 2011-2015.

INTRODUCTION: Burkholderia cepacia (B. cepacia) complex is composed of 20 phylogenetically closely related bacterial species. Some species have emerged as opportunistic pathogens in immunocompromised patients and are responsible for nosocomial outbreaks. The B. cepacia complex is a recognized respiratory pathogen in patients with cystic fibrosis. Burkholderia cenocepacia and Burkholderia multivorans (B. multivorans) are the most prevalent species in the world, according to the literature. However, research groups in Argentina have described a particular local epidemiology, with prevalence of Burkholderia contaminans (B. contaminans). METHODS: A total of 68 isolates of B. cepacia complex recovered of 46 cystic fibrosis patients attended at 14 hospitals distributed in 9 provinces of the country were studied. Identification was carried out by conventional phenotypic methods and was confirmed by recA gene sequencing. Sequences were analysed using the BLASTN program and comparing with B. cepacia complex type strains sequences deposited in GenBank. Antibiotic susceptibility tests were performed on isolates of the most prevalent species according to CLSI M45 guidelines. RESULTS: The prevalent specie was B. contaminans (49%, n = 33) followed by B. cenocepacia (25%; n = 17). The remaining species were Burkholderia seminalis (B. seminalis) (7%, n = 5), B. cepacia (7%, n = 5), B. multivorans (6%, n = 4), Burkholderia vietnamensis (5%, n=3) and Burkholderia pyrrocinia (1%; n = 1). The 46% of B. contaminans isolates were resistant to SXT and 76% sensitive to MIN, MEM and CAZ. The isolates of B. cenocepacia were 100% resistant to SXT and MIN and 47% to CAZ and MEM. B. seminalis showed high levels of resistance to TMS (80%), CAZ (60%) and MIN (60%), and 60% of the isolates showed intermediate sensitivity to MEM. CONCLUSION: Previous reports have described the prevalence of B. contaminans isolation from cystic fibrosis patients in Argentina, Spain and Portugal, and a case of two patients with cystic fibrosis in Ireland has recently been reported. Due to the high frequency with which B. contaminans is isolated in our country, it is necessary to promote the investigation of possible sources of infection and to understand the factors and mechanisms involved in the apparent greater transmissibility of this species. Different antimicrobial resistance profiles were detected between the species.

Enfermedad del legionario en Argentina: evolución de la estrategia diagnóstica en el laboratorio / Legionnaires' disease in Argentina: Evolution of the laboratory diagnostic strategy

Resumen La enfermedad del legionario (EL) es una neumonía aguda grave, que ocurre espo-rádicamente o como epidemias, y que, generalmente, requiere hospitalización. El objetivo deeste trabajo fue describir la experiencia en el abordaje diagnóstico de laboratorio de la ELen Argentina durante el período 2016-2021. Se analizaron 168 especímenes clínicos correspondientes a 93 casos de neumonía con sospecha de EL. Las pruebas de laboratorio incluyeron ladeterminación del antígeno soluble de Legionella pneumophila serogrupo 1 en orina, la detec-ción de ADN de Legionella spp. en secreciones respiratorias bajas, por métodos moleculares convencionales y comerciales de tipo sindrómico, y el cultivo en medio selectivo. Se confirmó EL en 12 pacientes. El antígeno urinario confirmó el diagnóstico de 8 de ellos. Se recuperó L. pneumophila mediante el cultivo del material respiratorio de 6 pacientes que correspondieron a casos de neumonía asociada a cuidados de la salud y que fueron previamente diagnosticados por el método molecular comercial. La mitad de ellos no presentó antigenuria detectable. En un único paciente no hubo antigenuria detectable ni recuperación de Legionella en cultivo, y la confirmación de EL se basó en la detección de ADN de Legionella spp. por PCR en secreción respiratoria y el vínculo epidemiológico con otro caso de EL confirmado por cultivo. La detección del antígeno urinario es la prueba diagnóstica de primera línea. Sin embargo, la incorporación de métodos moleculares complementarios ha demostrado evitar falsos negativos y contribuir a un mejor conocimiento de la verdadera incidencia de la enfermedad.

Abstract Legionnaires' disease (LD) is severe acute pneumonia that occurs in sporadic or epidemic form, and generally requires hospitalizaron. The objective of this work was to describe the experience in the LD laboratory diagnostic approach in Argentina during the period 2016-2021. The laboratory analyzed 168 clinical specimens from 93 cases of suspected LD pneu-monia. Laboratory tests included the detection of the soluble antigen of Legionella pneumophila serogroup 1 in urine sample, detection of DNA of Legionella spp. in lower respiratory secre-tions by conventional and commercial molecular methods and isolation in selective medium. LD was confirmed in 12 patients. The urinary antigen allowed the diagnosis for 8 patients. L. pneumophila was isolated from the respiratory material of 6 patients suffering from health care-associated pneumonia, who had been previously diagnosed using the commercial molecular method. Fifty percent of these cases did not show detectable urinary antigen. A single patient did not shows neither detectable antigenuria nor isolation of Legionella from the respiratory sample and was diagnosed as a confirmed case of LD by the detection of DNA of Legionella spp. by PCR directly from the respiratory secretion and the epidemiological link with another case of confirmed LD by culture. Urinary antigen detection is the first-line diagnostic test. However, the incorporation of complementary molecular methods has proved to avoid false negatives and contributed to a better understanding of the true incidence of the disease.

Dolosigranulum pigrum en absceso corneal / Dolosigranulum pigrum in corneal abscess

Resumen Dolosigranulum pigrum es un coco gram positivo, anaerobio facultativo, que forma parte de la microbiota oral y del tracto respiratorio superior. Aunque los reportes de infecciones por este microorganismo son escasos, se lo ha asociado a un amplio espectro de enfermedades infecciosas. Se describe el caso de un hombre adulto con un absceso corneal del que se aisló D. pigrum. El microorganismo fue identificado por espectrometría de masas (MALDI-TOF MS) y secuenciación del gen 16S ARNr. A su vez, se logró la identificación presuntiva mediante pruebas fenotípicas claves, como la disposición en racimos en la coloración de Gram, la prueba negativa de la catalasa, la producción de pirrolidonil arilamidasa y leucina aminopeptidasa, el crecimiento en NaCl al 6,5% y la hidrólisis de esculina. Los datos de la literatura y el presente caso respaldan la asociación del microorganismo con infecciones oculares, a menudo de curso destructivo, principalmente en pacientes de edad avanzada.

Abstract Dolosigranulum pigrum is a gram-positive, facultatively anaerobic coccus, which is part of the oral and upper respiratory tract microbiota. Although reports of infections by this microorganism are scarce, it has been associated with a wide spectrum of infectious diseases. The case of an elderly man with a lower corneal abscess, in which Dolosigranulum pigrum was isolated, is described. The microorganism was identified by mass spectrometry (MALDI-TOF MS) and by the sequencingof the 16S rRNAgene. Furthermore, the presumptive identification of the causative agent was achieved by using key phenotypic tests such as the cluster arrangement in Gram stain, the negative catalase test, the production of pyrrolidonyl arylamidase and leucine aminopeptidase activity, the growth in 6.5% NaCl and esculin hydrolysis. The data from the literature (and the present case) support the association of the microorganism with ocular infections, which often take a destructive course, mainly in elderly patients.

ARTICLESARS-CoV-2 and Chlamydia pneumoniae co-infection:A review of the literature / Coinfección por Chlamydia pneumoniae y SARS-CoV-2: Una revisión de la literatura

Abstract Bacterial co-pathogens are commonly identified in viral respiratory infections and are important causes of morbid-mortality. The prevalence of Chlamydia (C.) pneumoniae infection in patients infected with SARS-CoV-2 has not been sufficiently studied. The objective of the present review was to describe the prevalence of C. pneumoniae in patients with coronavirus disease 2019 (COVID-19). A search in MEDLINE and Google Scholar databases for English language literature published between January 2020 and August 2021 was performed. Studies evaluating patients with confirmed COVID-19 and reporting the simultaneous detection of C. pneumoniae were included. Eleven articles were included in the systematic review (5 case cross-sectional studies and 6 retrospective studies). A total of 18450 patients were included in the eleven studies. The detection of laboratory-confirmed C. pneumoniae infection varied between 1.78 and 71.4% of the total number of co-infections. The median age of patients ranged from 35 to 71 years old and 65% were male. Most of the studies reported one or more pre-existing comorbidities and the majority of the patients presented with fever, cough and dyspnea. Lymphopenia and eosinopenia were described in COVID-19 co-infected patients. The main chest CT scan showed a ground glass density shadow, consolidation and bilateral pneumonia. Most patients received empirical antibiotics. Bacterial co-infection was not associated with increased ICU admission and mortality. Despite frequent prescription of broad-spectrum empirical antimicrobials in patients with coronavirus 2-associated respiratory infections, there is a paucity of data to support the association with respiratory bacterial co-infection. Prospective evidence generation to support the development of an antimicrobial policy and appropriate stewardship interventions specific for the COVID-19 pandemic are urgently required.

Resumen Los patógenos bacterianos pueden detectarse en las infecciones respiratorias virales y son una causa importante de morbimortalidad. La prevalencia de Chlamydia pneumoniae en pacientes infectados con SARS-CoV-2 ha sido poco estudiada. El objetivo de la presente revisión fue describir la prevalencia de C. pneumoniae en pacientes con enfermedad por coronavirus 2019 (COVID-19). Para ello se realizó una búsqueda bibliográfica en Medline y Google Académico, entre enero de 2020 y agosto de 2021. De la revisión surgieron 11 artículos (cinco estudios de casos transversales y seis estudios retrospectivos), que incluyeron un total de 18.450 pacientes. La detección de C. pneumoniae varió entre el 1,78 y 71,4% del total de las coinfecciones. La media de edad de los pacientes osciló entre los 35 y 71 años y el 65% fueron hombres. En la mayoría de los estudios se informaron comorbilidades preexistentes y la mayor parte de los pacientes presentó fiebre, tos y disnea. Además, se describió linfopenia y eosinofilopenia en pacientes con COVID-19 coinfectados. La principal manifestación en la tomografía computarizada fue densidad de vidrio esmerilado, consolidación y neumonía bilateral. La mayoría de los pacientes recibió antibióticos de manera empírica. La coinfección bacteriana no se asoció con un aumento de ingresos en cuidados intensivos ni mortalidad. A pesar de la prescripción de antimicrobianos empíricos en pacientes con infecciones respiratorias asociadas a coronavirus existen pocos reportes de detección de coinfección bacteriana. Es necesario generar evidencia para el desarrollo de políticas antimicrobianas e intervenciones de administración apropiadas y específicas en la pandemia de COVID-19.

Evolución del desempeño de Laboratorios de Referencia de América Latina en la detección de mecanismos de resistencia a los antimicrobianos

[RESUMEN]. Objetivo. El objetivo es presentar los resultados del Programa Latinoamericano de Aseguramiento de la Calidad en Bacteriología y Resistencia a los Antimicrobianos (LA-EQAS) entre 2000 y 2018 y la evolución en la detección de mecanismos de resistencia de impacto clínico. Métodos. Los Laboratorios Nacionales de Referencia (LNR) participantes recibieron 25 encuestas con 10 cepas cada una, representando un total de 86 especies bacterianas y 40 mecanismos de resistencia. Para evaluar el desempeño de los LNR, se analizaron cinco indicadores: identificación bacteriana, interpretación de las pruebas de sensibilidad, rangos de las zonas de inhibición aceptables, mecanismo de resistencia inferido, y tiempo de demora en la respuesta. Resultados. La concordancia media fue 82,6% (rango: 74-95%) en la identificación bacteriana, 93,3% (85-98%) en la interpretación de las pruebas de sensibilidad, 84,6% (70-94%) en las zonas de inhibición, 82,5% (73-96%) en el mecanismo de resistencia inferido, y la demora en la respuesta, 34 días. Se observó una mejora en la detección de mecanismos de relevancia clínica como resistencia a meticilina, macrólidos y glucopéptidos en cocos gram positivos, y betalactamasas de espectro extendido, AmpC plasmídico y carbapenemasas en bacilos gram negativos. Conclusiones. El LA-EQAS es una excelente herramienta para la mejora continua de la calidad en el diagnóstico de las infecciones por microorganismos multirresistentes en los LNR de América Latina.

[RESUMEN]. Objetivo. El objetivo es presentar los resultados del Programa Latinoamericano de Aseguramiento de la Calidad en Bacteriología y Resistencia a los Antimicrobianos (LA-EQAS) entre 2000 y 2018 y la evolución en la detección de mecanismos de resistencia de impacto clínico. Métodos. Los Laboratorios Nacionales de Referencia (LNR) participantes recibieron 25 encuestas con 10 cepas cada una, representando un total de 86 especies bacterianas y 40 mecanismos de resistencia. Para evaluar el desempeño de los LNR, se analizaron cinco indicadores: identificación bacteriana, interpretación de las pruebas de sensibilidad, rangos de las zonas de inhibición aceptables, mecanismo de resistencia inferido, y tiempo de demora en la respuesta. Resultados. La concordancia media fue 82,6% (rango: 74-95%) en la identificación bacteriana, 93,3% (85-98%) en la interpretación de las pruebas de sensibilidad, 84,6% (70-94%) en las zonas de inhibición, 82,5% (73-96%) en el mecanismo de resistencia inferido, y la demora en la respuesta, 34 días. Se observó una mejora en la detección de mecanismos de relevancia clínica como resistencia a meticilina, macrólidos y glucopéptidos en cocos gram positivos, y betalactamasas de espectro extendido, AmpC plasmídico y carbapenemasas en bacilos gram negativos. Conclusiones. El LA-EQAS es una excelente herramienta para la mejora continua de la calidad en el diagnóstico de las infecciones por microorganismos multirresistentes en los LNR de América Latina.

[RESUMO]. Objetivo. O objetivo deste trabalho é apresentar os resultados do Programa Latino-Americano de Garantia da Qualidade em Bacteriologia e Resistência Antimicrobiana (LA-EQAS, na sigla em inglês) entre 2000 e 2018 e a evolução na detecção de mecanismos de resistência com impacto clínico. Métodos. Os Laboratórios Nacionais de Referência (LNRs) participantes receberam 25 inquéritos com 10 cepas bacterianas cada, representando um total de 86 espécies bacterianas e 40 mecanismos de resistência. Para avaliar o desempenho dos LNRs, foram analisados cinco indicadores: identificação bacteriana, interpretação dos testes de sensibilidade, faixas das zonas de inibição aceitáveis, mecanismo de resistência inferido e tempo de demora na resposta. Resultados. A concordância média foi de 82,6% (intervalo: 74-95%) na identificação bacteriana, 93,3% (85-98%) na interpretação dos testes de sensibilidade, 84,6% (70-94%) nas zonas de inibição, 82,5% (73-96%) no mecanismo de resistência inferido e 34 dias na demora na resposta. Observou-se uma melhoria na detecção de mecanismos clinicamente relevantes, como a resistência a meticilina, macrolídeos e glicopeptídeos em cocos Gram-positivos, beta-lactamases de espectro ampliado, AmpC plasmídica e carbapenemases em bacilos Gram-negativos. Conclusões. O LA-EQAS é uma excelente ferramenta para a melhoria contínua da qualidade no diagnóstico de infecções por microrganismos multirresistentes nos LNRs da América Latina.

Desarrollo y evaluación de una base de datos in house para la identificación rápida de Burkholderia contaminons por EM MALDI-TOF / Development and evaluation of an in-house database for quick identification of Burkholderia contaminans by MALDI-TOF MS

La espectrometría de masas (EM) (matrix assisted laser desorption ionization-time of flight) MALDI-TOF demostró ser una herramienta robusta para la identificación de numerosos grupos taxonómicos. No obstante, presenta limitaciones. Una ventaja clave de la técnica es la flexibilidad para la incorporación de espectros proteicos de microorganismos ausentes en la base de datos comercial. Dada la prevalencia de Burkholderia contaminans en los pacientes fibroquísticos en Argentina, y a que en ellos es crucial el diagnóstico microbiológico rápido y confiable, la EM MALDI-TOF surge como una herramienta estratégica. El objetivo del trabajo fue desarrollar una base de datos adicional con espectros peptídicos de aislamientos de referencia de B. contaminans. La misma demostró ser exitosa para la identificación del 97% de los aislamientos analizados. Por lo cual la EM MALDI-TOF con la base de datos extendida resultó ser una herramienta útil para la identificación y diferenciación de otras especies relacionadas a B. contaminans.

MALDI-TOF (matrix assisted laser desorption ionization-time of flight) mass spectrometry (MS) proved to be a robust tool for the identification of numerous taxonomic groups. However, it has limitations. A key advantage of this technique is the flexibility for the incorporation of protein profiles of microorganisms not included in the commercial database. Due to the prevalence of Burkholderia contaminans in fibrocystic patients in Argentina and the fact that rapid and reliable microbiological diagnosis is crucial in them, MALDI-TOF MS emerges as a strategic tool. The aim of this work was to develop an additional database with peptide spectra of reference isolates of B. contaminans. This database demonstrated to be successful for the identification of 97% of the isolates analyzed. Therefore, MALDI-TOF MS with the extended database was a useful tool for the identification and differentiation of other related species to B. contaminans.