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Resumen Las infecciones hospitalarias causadas por bacilos gram negativos resistentes a carbapenems (BGNCR) están asociadas al aumento de morbimortalidad y gasto sanitario. La identificación mediante cultivos de vigilancia y las medidas de control de infecciones permiten reducir su diseminación. El objetivo del estudio fue evaluar el impacto de un programa de vigilancia integrado a protocolos de control de infecciones sobre la incidencia de BGNCR y conocer su epidemiología molecular en una unidad de cuidados intensivos. Se realizaron auditorías seguidas de un programa de cultivo de vigilancia activa y caracterización molecular de BGNCR, antes y después de la implementación de programas de prevención y control de infecciones. El screening microbiológico se realizó en medios cromogénicos; la caracterización molecular de p-lactamasas (blaKPC, bla0XA-48-like, blaVIM, blaiMP, blaNDM, blaSHV y blaCTx-M) por PCR y la tipificación molecular por PFGE y MLST para Klebsiella pneumoniae. El protocolo desarrollado permitió reducir la colonización global de 16,92% al 9,67%. La diseminación de K. pneumoniae fue a expensas de diversos clones portadores de KPC-2 asociada a BLEE SHV-2 y CTX-M-15, y distribuidos en varios secuenciotipos (ST17, ST13, ST2256, ST353); no se observó persistencia de un clon particular y ningún aislamiento presentó factores de virulencia asociados a hipervi-rulencia. Los aislamientos de Acinetobacter baumannii fueron mayoritariamente productores de IMP-1. El análisis PFGE individualizó 3 clusters, asumiendo que la diseminación fue clonal. Abstract Hospital-acquired infections caused by carbapenem-resistant Gram-negative bacteria (CRGNB) have been increasingly reported worldwide and are associated with high rates of mortality especially in intensive care units(ICUs). Early identification through rectal surveillance cultures and implementation of infection control measures(ICM) including contact precautions, staff education on cleaning and hand hygiene may reduce the spread of these microorganisms. The aim of this work was to assess the impact of enhanced ICM on CRGNB colonization and to describe the molecular epidemiology of these bacteria in a polyvalent ICU in a tertiary level hospital. A prospective study including audits and active surveillance culture program, with molecular characterization, was conducted before and after the implementation of prevention programs and infection control measures. Microbiological screening was performed in chromogenic media; PCR targeting p-lactamases genes (ó/qkpc, óíQndm, blaviM and blaoxA-48, blasHv and ó/qctx-m), molecular typing by PFGE; and MLST in K. pneumoniae were performed. CRGNB colonization was reduced from 16.92% to 9.67% upon implementing the infection control measures. In K. pneumoniae the most frequent carbapenemase type was KPC-2 associated with SHV-2 and CTX-M-15, and was disseminated in various STs (ST17, ST13, ST2256, ST353); there was no persistence of particular clones and virulence factors showed no association with hypervirulence. IMP-1 carbapenemase predominated in A. baumannii and the PFGE analysis individualized 3 clusters, assuming that the dissemination in the ICU was clonal. The early detection of patients colo-nized with CRBGN by using epidemiological surveillance cultures and the implementation of prophylactic measures are key to reducing the incidence of these microorganisms.

Introduction. Klebsiella aerogenes is a nosocomial pathogen associated with drug resistance and healthcare-associated infections. Gap Statement. K. aerogenes is associated with hospital-acquired infections with the ability to acquire mechanisms of resistance to reserve antimicrobials; its clinical behaviour has been poorly documented. Objective. We proposed to investigate an outbreak of carbapenem-resistant K. aerogenes in a hospital that persisted for 4 months. Methods. The primary aim was to evaluate the molecular characteristics and the clonal relationships among the isolates. We characterized isolates by polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE). The information was integrated with clinical and epidemiological data. Results. Fourteen strains were disseminated in an intensive care unit and different wards at the hospital. The overall mortality was 42.8 %, and mortality attributed to infection was 21.4 %; strains showed high rates of resistance to most of the antimicrobials tested and carried bla KPC-2, bla SHV-2 and bla CTXM-15 genes. PFGE analysis indicated 2 PFGE groups; 12/14 isolates were associated with subgroup A and were likely to be primarily responsible for the first isolation and subsequent dissemination. The outbreak characteristics data showed prolonged hospitalization and previous use of antibiotics as potential risk factors. Conclusion. We consider that it is essential to perform phenotypic and genotypic identification of early genetic resistance mechanisms in K. aerogenes isolates, not only from infection sites but also from colonization, to prevent the spread of these multidrug-resistant (MDR) isolates.

Objectives: The emergence and spread of hypermucoviscous KPC-2-producing Klebsiella pneumoniae strains belonging to the sequence type 25 (ST25) clone was reported recently in Northwest Argentina as a leading cause of nosocomial infections. The aim of this work was to perform whole-genome sequencing (WGS) to analyse antimicrobial resistance genes (ARGs), virulence factors and colonisation-associated genes in two carbapenem-resistant KPC-2-producing ST25 K. pneumoniae strains isolated from hospitalised patients. Methods: Classical microbiological methods were applied to recover K. pneumoniae LABACER 01 from a bone sample and LABACER 27 from the respiratory tract of two hospitalised patients. Bacteria were identified by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF). WGS was performed using an Illumina MiSeq platform. Genome annotation and analysis were performed with available databases and bioinformatic tools. Results: Genomic analysis revealed a genome of 5 598 020 bp with 19 further characterised ARGs in strain LABACER 01, and a genome of 5 622 382 bp with 20 ARGs in strain LABACER 27. Bioinformatics analysis also predicted genomic regions associated with virulence factors and mucosal tissue colonisation. Conclusion: This study reports the genomic analysis of K. pneumoniae LABACER 01 and LABACER 27, two hypermucoviscous carbapenem-resistant ST25 strains, which expands our knowledge on the antibiotic resistance, pathogenic mechanisms and biology of ST25 clones recently emerging in Argentina.

Objectives In Latin America, methicillin-resistantStaphylococcus aureus (MRSA) is a leading cause of nosocomial infections. Limited studies have addressed the molecular epidemiology of MRSA clones in Argentina, characterised by continuous human migratory movements. The aim of this study was to describe the MRSA epidemiology, including distinct patient populations from different regions of the country. Methods MRSA strains were collected in epidemiological studies conducted from 2009 to 2015 in three cities (Formosa, Cordoba and Tucuman) and involving four population groups: community adult patients; hospitalised adults; hospitalised children; and healthy children (nasal colonisation). Antimicrobial susceptibility testing, SCCmec and Panton–Valentine leukocidin (PVL) typing, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed. Results A total of 120 MRSA isolates were recovered with an important population diversity in the groups studied; in community adult patients, MRSA isolates corresponded to ST5, ST267 and ST1619; from hospitalised adults they were ST97, ST5, ST72, ST125, ST200, ST647, ST747, ST935 and ST2941; from hospitalised children they were ST5, ST30, ST34, ST1163 and ST1619; and from colonised children they were ST5, ST125, ST34, ST100, ST1619, ST207 and ST1163. Results of SCCmec typing showed SCCmec I, SCCmec IIIA, SCCmec IV and SCCmec ND associated or not with PVL genes. Conclusions MRSA genetic lineages have differing distribution in the three regions. The most prevalent was ST5 in colonisation, community and invasive settings. Here we describe ST34-SCCmec IV clone for the first time in the hospitalised paediatric population. These findings contribute to the understanding of epidemiological changes in recent years.

IntroductionKlebsiella aerogenes is a nosocomial pathogen associated with drug resistance and healthcare-associated infections. We pursued this study to investigate an outbreak of clinical carbapenem-resistant K. aerogenes(CRKA) in an argentinian tertiary hospital which persisted for 4 months despite aggressive infection control measures. The primary goals aimed to evaluate the molecular characteristics and the clonal relationships among the CRKA isolates.MethodsWe characterized CRKA isolates by multiplex PCR and PFGE. The information was integrated with clinical and epidemiologic data.ResultsThe 14 CRKA strains were disseminated in an adult intensive care unit (50%) and five different wards. In patients who received antimicrobial treatment, 8 staggered to directed treatment, mainly with amikacin(6/8) and/or carbapenemes(5/8). The overall mortality was 42.8%, and the attributed mortality to CRKA infection was 21.4%, strains showed high rates of resistance to most of the antimicrobials without resistance to Amikacin and Tigecycline, and carried the blaKPC-2, blaSHV-2 and blaCTXM-15 genes. The PFGE indicated 2 distinct groups; 12/14 CRKA isolatesassociated with the dominant subgroup A and likely to be primarily responsible for the first isolation and subsequent dissemination in the hospital.ConclusionThe outbreak characteristics data showed prolonged hospitalization and previous use of broad-spectrum antibiotics as potential risk factors for the acquisition of CRKA.

Hospital-acquired infections caused by carbapenem-resistant Gram-negative bacteria (CRGNB) have been increasingly reported worldwide and are associated with high rates of mortality especially in intensive care units(ICUs). Early identification through rectal surveillance cultures and implementation of infection control measures(ICM) including contact precautions, staff education on cleaning and hand hygiene may reduce the spread of these microorganisms. The aim of this work was to assess the impact of enhanced ICM on CRGNB colonization and to describe the molecular epidemiology of these bacteria in a polyvalent ICU in a tertiary level hospital. A prospective study including audits and active surveillance culture program, with molecular characterization, was conducted before and after the implementation of prevention programs and infection control measures. Microbiological screening was performed in chromogenic media; PCR targeting β-lactamases genes (bla

Carbapenemase-producing Klebsiella pneumoniae (CRKP) are increasingly reported worldwide being necessary the local epidemiological monitoring. Our aim was to characterize the hypermucoviscous CRKP isolates collected in our hospital during a 6 months period. Carriage of the carbapenemase genes (blaKPC, blaNDM, blaVIM and blaOXA-48), extended spectrum β-lactamases (blaSHV-2, blaCTX-M) and the virulence genes (magA, k2A, rmpA, wabG, uge, allS, entB, ycfM, kpn, wcaG, fimH, mrkD, iutA, iroN, hly and cnf-1) were determined by multiplex-PCR. Genetic relationship among the isolates was performed by PFGE and MLST. A total of 35 isolates were recovered, being the urinary and respiratory tract the most common infection sites (34.2%). The blaKPC-2 gene was present in all the isolates, coexisting with blaCTX-M-2 (45.7%), blaSHV-2 (28.6%), and blaCTX-M-2/blaSHV-2 (14.3%). The capsular serotype K2 corresponded with 68.6% of the isolates. Virulence factors frequency were variable [adhesins (97.1%), siderophores (94.3%) and phagocytosis resistance (wabG 48.5%, uge 80% and ycfM 57.1%)]. A total of 10 STs were identified although 40% of them clustered on ST25-CC65, and 17% to ST17. The incidence of KPC-2-producing K. pneumoniae reported by the hospital was 0.290 per 1000 admissions. In summary we described an epidemic scenario of multidrug resistant hypermucoviscous KPC-2 producing ST25 K. pneumoniae in our institution.