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BACKGROUND: Vancomycin-resistant Enterococcus faecium (VREfm) is an important agent of hospital-acquired infection. VanA phenotype is characterized by resistance to high levels of vancomycin and teicoplanin and is encoded by the vanA gene, whereas VanD phenotype is characterized by resistance to vancomycin and susceptibility or intermediate resistance to teicoplanin; however, some isolates carry a VanD phenotype with a vanA genotype, but there are many gaps in the knowledge about the genetic mechanisms behind this pattern. OBJECTIVE: To characterize the genetic structure, clonality, and mobile genetic elements of VRE isolates that display a VanD-vanA phenotype. RESULTS: All vanA VRE-fm isolates displayed minimum inhibitory concentration (MIC) for vancomycin > 32µg/mL and intermediate or susceptible MIC range for teicoplanin (8–16µg/mL). The isolates were not clonal, and whole-genome sequencing analysis showed that they belonged to five different STs (ST478, ST412, ST792, ST896, and ST1393). The absence of some van complex genes were observed in three isolates: Ef5 lacked vanY and vanZ, Ef2 lacked vanY, and Ef9 lacked orf1 and orf2; moreover, another three isolates had inverted positions of orf1, orf2, vanR, and vanS genes. IS1542 was observed in all isolates, whereas IS1216 in only five. Moreover, presence of other hypothetical protein-encoding genes located downstream the vanZ gene were observed in six isolates. CONCLUSION: VRE isolates can display some phenotypes associated to vanA genotype, including VanA and VanB, as well as VanD; however, further studies are needed to understand the exact role of genetic variability, rearrangement of the transposon Tn1546, and presence of insertion elements in isolates with this profile.

We described a MRSA bloodstream infection outbreak that was rapidly identified and controlled in a Neonatal Intensive Care Unit after implementation of a bundle of measures, including PCR-screening and HCW decolonization. We found 35% of healthcare workers(HCW) colonized with S. aureus by PCR, one of them that presented skin lesion positive for MSSA (same clone and spa type than two patients). Our findings raise the hypothesis that the outbreak could be related to HCW colonization.

In this study, we describe a case report of gonococcal arthritis in a Systemic Lupus Erythematosus patient. Although several mechanisms favor disseminated gonococcal infection (DGI) in patients immunosuppressed by SLE, this association is rarely reported in literature. We performed whole genome sequencing (WGS) of the etiologic agent involved and molecular analysis using a global collection of Neisseria gonorrhoeae strains. Ours is the only sample derived from synovial fluid identified in this collection, the others being from the usual anatomical sites. Antimicrobial susceptibility was determined by disk diffusion and Etest, and WGS was conducted to determine multilocus sequence typing profiles, group isolates based on core genome single nucleotide polymorphisms (SNP), and identify virulence genes and antimicrobial resistance determinants. The N. gonorrhoeae samples in the global collection were highly heterogeneous. The SNP tree had a total 19,532 SNPs in 320 samples. Our sample displayed resistance to ciprofloxacin (MIC = 2 μg/mL) and tetracycline (zone diameter = 0 mm) belonged to ST 1588 and was not closely related to any isolate in the global collection of N. gonorrhoeae strains. The isolate had genetic features related to beta-lactam, tetracycline and quinolone resistance. Seventy-one virulence genes were identified in our sample, belonging to the following classes: adherence, efflux pump, immune modulator, invasion, iron uptake, protease and stress adaptation. Moreover, no virulence genes for immune evasion and toxin were identified.

Carbapenem-resistant Klebsiella pneumoniae (CRK) infections are a growing concern in immunocompromised patients. The aim of the present study was to evaluate the impact of CRK colonization and infection in overall mortality for haematopoietic stem-cell transplant (HSCT) patients. We also aimed to investigate resistance and virulence profiles of CRK isolates and assess their epidemiological and genetic relatedness. Patients in the HSCT unit were screened for colonization with CRK with weekly rectal swab or stool cultures and placed under contact precautions. We defined CRK colonization as positive culture from a swab or stool sample grown in MacConkey agar with meropenem at 1 µg ml−1. Demographic and clinical data were retrieved from the patients’ charts and electronic records. According to resistance mechanisms and pulsed field gel electrophoresis profile, isolates were selected based on whole-genome sequencing (WGS) using MiSeq Illumina. Outcomes were defined as overall mortality (death up to D+100), and infection-related death (within 14 days of infection). We report a retrospective cohort of 569 haematopoietic stem-cell transplant patients with 105 (18.4 %) CRK colonizations and 30 (5.3 %) infections. blaKPC was the most frequent carbapenemase in our cohort with three isolates co-harbouring blaKPC and blaNDM. We found no difference in virulence profiles from the CRK isolates. There were also no significant differences in virulence profiles among colonization and infection isolates regarding genes encoding for type 1 and 3 fimbriae, siderophores, lipopolysaccharide and colibactin. In clonality analysis by PFGE and WGS, isolates were polyclonal and ST340 was the most prevalent. Overall survival at D+100 was 75.4 % in in CRK-colonized (P=0.02) and 35.7 % in infected patients and significantly lower than non-colonized patients (85.8 %; P

Carbapenem-resistant

Despite the widespread use of chlorhexidine (CHX) to prevent infection, data regarding the in vitro action of CHX against methicillin-resistant Staphylococcus aureus (MRSA) are limited. Clinical isolates from Hospital das Clinicas, Sao Paulo, Brazil, identified during 2002/2003 and 2012/2013 were studied to describe the susceptibility to CHX and mupirocin, molecular characteristics, and virulence profile of MRSA. Susceptibility test to Mupirocin was performed by the disk diffusion method and to CHX by the agar dilution technique. PCR for virulence genes, mecA gene and Staphylococcal Cassette Chromosome mec (SCCmec) types were investigated as well. Mupirocin- and CHX-resistant isolates were sequenced using the IlluminaTM plataform. Two hundred and sixteen MRSA clinical isolates were evaluated: 154 from infected and 62 from colonized patients. Resistance to mupirocin was observed in four isolates assigned as SCCmec type III and STs (ST05; ST239 and ST105) carrying mupA and blaZ, two of them co-harboring the ileS gene. Only one isolate assigned as SCCmec type III was resistant to CHX (MIC of 8.0 μg.mL-1) and harbored the qacA gene. Resistance to chlorhexidine and mupirocin were found in isolates carrying qacA and mupA in our hospital. Since these genes are plasmid-mediated, this finding draws attention to the potential spread of resistance to mupirocin in our hospital.

Carbapenem-resistant Enterobacteriaceae are a worldwide health problem and isolates carrying both blaKPC-2 and blaNDM-1 are unusual. Here we describe the microbiological and clinical characteristics of five cases of bloodstream infections (BSI) caused by carbapenem-resistant Klebsiella pneumoniae and Serratia marcescens having both blaKPC-2 and blaNDM-1. Of the five blood samples, three are from hematopoietic stem cell transplantation patients, one from a renal transplant patient, and one from a soft tissue surgical patient. All patients lived in low-income neighbourhoods and had no travel history. Despite antibiotic treatment, four of five patients died. The phenotypic susceptibility assays showed that meropenem added either EDTA, phenylboronic acid (PBA) or both, increased the zone of inhibition in comparison to meropenem alone. Molecular tests showed the presence of blaKPC-2 and blaNDM-1 genes. K. pneumoniae isolates were assigned to ST258 or ST340 by whole genome sequencing. This case-series showed a high mortality among patients with BSI caused by Enterobacteriae harbouring both carbapenemases. The detection of carbapenemase-producing isolates carrying both blaKPC-2 and blaNDM-1 remains a challenge when using only phenotypic assays. Microbiology laboratories must be alert for K. pneumoniae isolates producing both KPC-2 and NDM-1.

The plasmid-mediated colistin-resistance gene named mcr-1 has been recently described in different countries and it became a public health challenge. Of note, few studies have addressed the spread of Escherichia coli harboring the mcr-1 gene in both, community and hospital settings. A total of seven colistin-resistant E. coli carrying mcr-1, collected from 2016 to 2018, from community (n=4), healthcare-acquired infections (n=2) and colonization (n=1) were identified in three high complexity hospitals in Sao Paulo, Brazil. These colistin-resistant isolates were screened for mcr genes by PCR and all strains were submitted to Whole Genome Sequencing and the conjugation experiment. The seven strains belonged to seven distinct sequence types (ST744, ST131, ST69, ST48, ST354, ST57, ST10), and they differ regarding the resistance profiles. Transference of mcr-1 by conjugation to E. coli strain C600 was possible in five of the seven isolates. The mcr-1 gene was found in plasmid types IncX4 or IncI2. Three of the isolates have ESBL-encoding genes (bla CTX-M-2, n=2; bla CTX-M-8, n=1). We hereby report genetically distinct E. coli isolates, belonging to seven STs, harboring the mcr-1 gene, associated to community and healthcare-acquired infections, and colonization in patients from three hospitals in Sao Paulo. These findings point out for the potential spread of plasmid-mediated colistin-resistance mechanism in E. coli strains in Brazil.

Objectives Enterobacterales and other non-fermenting Gram-negative bacteria have become a threat worldwide owing to the frequency of multidrug resistance in these pathogens. On the other hand, efficacious therapeutic options are quickly diminishing. The aims of this study were to describe the susceptibility of 50 multiresistant Gram-negative bacteria, mostly pan-resistant, against old and less-used antimicrobial drugs and to investigate the presence of antimicrobial resistance genes. Methods A total of 50 genetically distinct isolates were included in this study, including 14 Acinetobacter baumannii (belonging to ST79, ST317, ST835 and ST836), 1 Pseudomonas aeruginosa (ST245), 8 Serratia marcescens and 27 Klebsiella pneumoniae (belonging to ST11, ST340, ST258, ST16, ST23, ST25, ST101, ST234, ST437 and ST442). The isolates were submitted to antimicrobial susceptibility testing and whole-genome sequencing to evaluate lineages and resistance genes. Results Our results showed that some strains harboured carbapenemase genes, e.g. blaKPC-2 (28/50; 56%) and blaOXA-23 (11/50; 22%), and other resistance genes encoding aminoglycoside-modifying enzymes (49/50; 98%). Susceptibility rates to tigecycline (96%) in all species (except P. aeruginosa), to minocycline (100%) and doxycycline (93%) in A. baumannii, to ceftazidime/avibactam in S. marcescens (100%) and K. pneumoniae (96%), and to fosfomycin in S. marcescens (88%) were high. Chloramphenicol and quinolones (6% susceptibility each) did not perform well, making their use in an empirical scenario unlikely. Conclusions This study involving genetically distinct bacteria showed promising results for tigecycline for all Gram-negative bacteria (except P. aeruginosa), and there was good activity of minocycline against A. baumannii, ceftazidime/avibactam against Enterobacterales, and fosfomycin against S. marcescens.

Serratia marcescens is an emerging opportunistic pathogen with high genetic diversity. We described microbiological characteristics of isolates and also risk factors for infections caused by carbapenem-resistant S. marcescens(CrSm). A retrospective study of patients colonized(N=43) and infected(N=20) by CrSm over a three-year period was conducted. Polymerase chain reaction(PCR) for carbapenemases genes and molecular typing of all available strains was performed; Forty-two isolates were analyzed, including three environmental samples identified during an outbreak. Thirty-five CrSm carried blaKPC-2; one isolate was blaNDM-positive and four isolates carried blaOXA-101. The genomes were grouped into three clusters with 100% bootstrap; three patterns of mutations on ompC and ompF were found. The strains carried virulence genes related to invasion and hemolysis and the environmental strains presented less mutations on the virulence genes than clinical strains. The multivariate analysis showed that previous use of polymyxin(p=0.008) was an independent risk factor for infection by CrSm. Our study highlighted that blaKPC-2 in association with ompC, ompF mutation was the most frequent mechanism of resistance in our hospital, and that previous use of polymyxin was an independent risk factor for CrSm. There is a predominant clone, including the environmental isolates, suggesting that cross-transmission was involved in the dissemination of this pathogen.

Background: Although guidelines recommend the use of chlorhexidine gluconate (CHG) for hand hygiene (HH), the impact of its routine use on antimicrobial resistance is not clear. Objective: To analyze the impact on the CHG susceptibility among isolates obtained from hands of HCW during its routine use for HH. Methods: We conducted a crossover study at 4 medical-surgical wards of a tertiary-care hospital in São Paulo, Brazil. In 2 units (intervention group), we established routine use of CHG for HH. For the other 2 units (control group), regular soap was provided. The availability of alcohol formulation for HH was not changed during the study. Every 4 months we swapped the units, ie, those using CHG changed for regular soap and vice versa. At baseline, we cultured the hands of HCWs. Only nursing staff hands were investigated. For hand culturing, HCWs placed their hands inside a sterile bag containing a solution of phosphate-buffered saline, Tween 80, and sodium thiosulfate. After the solution incubated overnight, it was inoculated onto brain-heart infusion. Next, it was plated on McConkey and Mannitol agar. MALDI-TOF was used for identification. Agar dilution was performed for Staphylococcus spp. We selected all Staphylococcus spp with MIC ≥ 8 and performed inhibition of efflux pump test. For isolates that showed a decrease of 2 dilutions, we searched the gene qacA/B by polymerase chain reaction. Results: We obtained 262 samples from HCW hands yielding 428 isolates. The most frequent genera were Staphylococcus spp (58%), Acinetobacter spp (8%), Enterobacter spp (8%), Stenotrophomonas spp (5%), Klebsiella spp (4%), Pseudomonas spp (3%), and others (14%). Staphylococcus spp were less frequent in the intervention compared to control group (43% vs 61%; OR, 0.48; 95% CI, 0.29–0.69; P = .005). Among all Staphylococcus spp, the proportion of chlorhexidine resistance (RCHG; MIC ≥ 8) was 12%. All resistant isolates recovered susceptibility after inoculation with pump-efflux inhibitor. For pump-inhibited isolates, 53% had the gene qacA/B amplified by PCR. We did not investigate RCHG among gram-negative isolates. There was a nonsignificant increase in Staphylococcus spp RCHG in the intervention group (4% to 6%; P = .90). Healthcare-acquired infection rates did not change significantly during the intervention. The consumption of CHG increased from 7.3 to 13.9 mL per patient day. Conclusions: We did not detect a significant difference in RCHG during the routine use of CHG for HH, although we observed increasing resistance. Further investigation is needed to clarify other reasons for increasing MIC to CHG.Funding: NoneDisclosures: None

Empirical use of linezolid has been advocated in neutropenic febrile patients colonised by vancomycin-resistant enterococci (VRE) because of the risk of bloodstream infection (BSI). This study aimed to genetically describe a vancomycin-resistant Enterococcus faecium (VREfm) BSI isolate resistant to linezolid (VRLRE) in a patient previously colonised by VREfm and to determine the incidence of colonisation and infection by VREfm in a bone marrow transplant unit over a 10-year period. Data for VREfm colonisation and infection were evaluated. PCR for the vanA and vanB genes, pulsed-field gel electrophoresis (PFGE) and microdilution antimicrobial susceptibility testing (vancomycin, teicoplanin, linezolid and aminoglycosides) were performed. Three isolates, including the VRLRE, were selected for whole-genome sequencing by Ion Torrent™, with E. faecium CP006620-Aus0085 used as a reference. Eighty-seven VREfm were analysed; all were linezolid-susceptible and harboured vanA, except for one blood isolate from a febrile neutropenic patient colonised by VREfm who received linezolid for 12 days and developed a BSI by VRLRE (linezolid MIC ≥ 8 μg/mL). Linezolid resistance was associated with a G2576T mutation in the 23SrRNA gene. PFGE analysis demonstrated that the 87 isolates belonged to four major clusters; however, the VRLRE presented only 50% similarity. Three sequence types (STs) were identified: ST412 (the predominant clone, which was more virulent compared with the other isolates); ST478 (linezolid-susceptible VREfm); and a novel ST named ST987 (VRLRE). SNP analysis showed a higher similarity between linezolid-susceptible VREfm and the predominant clone compared with VRLRE. VRLRE presented a G2576T mutation and belonged to a novel ST (ST987).

Introdução: Enterococcus resistente à vancomicina (VRE do inglês Vancomycin Resistant Enterococcus) é uma importante causa de infecção relacionada a assistência à saúde com alta morbidade e mortalidade principalmente nos pacientes imunocomprometidos sendo a segunda causa mais comum de infecções hospitalares nessa população de pacientes em alguns centros. O uso prolongado da terapia antimicrobiana com vancomicina e outras drogas, são fatores de risco associados com a disseminação desse patógeno. Além disso, espécies de enterococos podem apresentar fatores de virulência tais como: substância de agregação (asa1), gelatinase (gelE), citolisina (cylA), proteína de superfície enterococo (esp) e hidrolase glicosil (hylefm). Entretanto, o papel da virulência na colonização e infecção por VRE é controverso. Objetivos: Avaliar o perfil clonal, virulência e resistência de 86 isolados de VRE (80 E. faecium e 06 E. faecalis) de infecção e colonização de 76 pacientes com doenças hematológicas e/ou submetidos a transplante de Medula Óssea (TMO) internados no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP) no período de 10 anos (2005-2014). Material e Métodos: Foram realizadas concentração inibitória mínima para: vancomicina, teicoplanina, linezolida, gentamicina e estreptomicina em alta concentração (HLAR); Avaliação da clonalidade por eletroforese em campo pulsado (PFGE); Detecção dos mecanismos de resistência (vanA e vanB) e de virulência (esp, asa1, gelE, cylA e hylefm) pela técnica de PCR e sequenciamento total do genoma de dezoito isolados selecionados de acordo com a clonalidade. Foi criado um banco de dados no programa Epiinfo (CDC) com variáveis clinicas e demográficas dos pacientes. A proporção de isolados de colonização portadores de genes de virulência foi comparada com os isolados de infecção assim como a proporção de isolados de infecção portadores de genes de virulência que evoluíram para óbito. O valor de p < 0,005 foi considerado significativo. Resultados: Trinta e quatro pacientes eram colonizados e 42 infectados por VRE (28 eram infecção de corrente sanguínea), 48 pacientes eram transplantados dos quais 32 eram alogênicos. A mortalidade em 14 dias foi de 21.0% e durante a hospitalização de 53.9%. Todos os isolados foram resistentes à vancomicina e 87,3% à teicoplanina. Resistência a gentamicina e estreptomicina em alta concentração (HLAR) foi observada em 08 e 59 isolados respectivamente. Um isolado apresentou resistência a linezolida identificado pela primeira vez na unidade. O gene vanA foi detectado em todos os isolados. Quanto aos genes de virulência, 96,5% de isolados foram positivos para o gene esp e 69,8% para os genes gelE e asa1. Isolados de infecção de E. faecium carrearam mais genes de virulência: esp (100%), gelE (80,0%) e asa1 (75,5%) e o gene gelE foi significativamente mais frequente entre isolados de infecção que de colonização (p=0,008). Infecções causadas por isolados de E. faecium positivos para o gene asa1 foram significantemente associadas com maior mortalidade (p < 0,05). Quinze diferentes Pulsed field type (PFT) foram observados entre os isolados de E. faecium e 06 entre os isolados de E. faecalis. Dezessete E. faecium foram sequenciados e diferentes sequencias tipo (ST) foram observadas (ST412, ST478, ST78 e ST896) já descritas em outros estudos no Brasil. O isolado resistente a linezolida apresentou mutação no domínio V do gene 23S rRNA com um perfil alélico diferente, caracterizando um novo ST (ST987) descrito pela primeira vez no Brasil. Todos os ST observados nos isolados de E. faecium pertencem ao complexo clonal 17, dos quais dois STs (ST963, ST792) foram descritos pela primeira vez no país. O isolado de E. faecalis sequenciado pertencia ao ST9 e ao complexo clonal 9 já descrito por outros autores. Conclusão: Nosso estudo observou que E. faecium foi predominante em nosso hospital e os ST circulantes pertenciam ao CC17. Os isolados de infecção foram mais virulentos que os isolados de colonização e o gene gelE foi significativamente mais frequente nos isolados de infecção. Infecções causadas por isolados de E. faecium positivos para o gene asa1 foram associadas com a alta mortalidade. Este achado pode ser útil para controlar a disseminação de E. faecium no ambiente hospitalar e em pacientes hematológicos Introduction: Vancomycin Resistant Enterococcus (VRE) is a important cause of health care-associated infection with high morbidity and mortality, mainly in immunocompromised patients, being the second most common cause of hospital infections in this population of patients in some centers. Prolonged use of antimicrobial therapy with vancomycin and other drugs are risk factors associated with the spread of this pathogen. In addition, enterococcal species may present virulence factors such as: aggregation substance (asa1), gelatinase (gelE), cytolysin (cylA), enterococcal surface protein (esp) and glycosyl hydrolase (hylefm). However, the role of virulence on VRE colonization and infection is controversial. Objectives: To evaluate the clonal profile, virulence and resistance of 86 isolates of VRE (80 E. faecium and 06 E. faecalis) from infection and colonization of 76 patients with hematological diseases and / or submitted to bone marrow transplantation (BMT) at Hospital das Clinics of the Medical School of the University of São Paulo (HC-FMUSP) in the period of 10 years (2005-2014). Material and Methods: Minimum inhibitory concentration to vancomycin, teicoplanin, linezolid, gentamicin and streptomycin in high concentration (HLAR) was performed; Clonality of isolates by pulsed field electrophoresis (PFGE) was evaluated; Detection of resistance (vanA and vanB) and virulence (esp, asa1, gelE, cylA and hylefm) genes by PCR technique and whole genome sequencing of eighteen isolates selected based on clonality. Results: All isolates were resistant to vancomycin and 87.3% to teicoplanin. Resistance to gentamicin and streptomycin in high concentration (HLAR) was observed in 08 and 59 isolates respectively. One isolate presented resistance to linezolid observed for the first time in the unit. The vanA gene was detected in all isolates. Regarding virulence genes, 96.5% of isolates were positive for the esp gene and 69.8% for the gelE and asa1 genes. Isolates of E. faecium infection carried more virulence genes: esp (100%), gelE (80.0%) and asa1 (75.5%) and gelE gene was significantly more frequent among infection isolates than colonization (p = 0.008). Infections caused by E. faecium isolates carrying the asa1 gene were significantly associated with higher mortality (p < 0.05). Fifteen different Pulsed field type (PFT) were observed among the isolates of E. faecium and 06 among E. faecalis isolates. Seventeen E. faecium were sequenced and the following sequences type (ST) were observed (ST412, ST478, ST78 and ST896) all of them already described in Brazil. The linezolid-resistant isolate showed the 23S gene Vdomain mutation with a different allelic profile, characterizing a new ST (ST987) described for the first time in our study. All STs observed in E. faecium isolates belong to clonal complex 17. Two other STs (ST963, ST792) were identified for the first time in the country. The E. faecalis isolate belong to ST9 and clonal complex 9 already described by other authors in Brazil. Conclusion: Our study observed that E. faecium was predominant in our hospital and the circulating STs belonged to CC17 a virulent lineage. E. faecium infection isolates were more virulent than colonization isolates and harbored significantly more gelE gene. It appears that infections caused by E. faecium isolates carrying asa1 gene evolved more frequently to death. This finding may be useful to control the spread of E. faecium in the hospital environment and in haematological patients

Summary Background Vancomycin-resistant enterococci (VRE) are an important agent of colonization and infection in haematology patients. However, the role of virulence on VRE colonization and infection is controversial. Aim To characterize the lineage, virulence and resistance profile of VRE infection and colonization isolates; as well as their impact on outcome of haematology patients using a regression logistic model. Methods Eighty-six isolates (80 Enterococcus faecium and six E. faecalis) from 76 patients were evaluated. Polymerase chain reaction for resistance and virulence genes, and pulsed-field gel electrophoresis and whole genome sequencing of the major clusters, were performed. Bivariate and multivariate analyses were carried out to evaluate the role of virulence genes on outcome. Findings All isolates harboured the vanA gene. Regarding the virulence genes, 96.5% of isolates were positive for esp, 69.8% for gelE and asa1 genes. VRE infection isolates were more virulent than colonization isolates and harboured more often the gelE gene (P = 0.008). Infections caused by VRE carrying asa1 gene resulted more frequently in death (P = 0.004), but only the predominant clone remained as protector in the multivariate model. The E. faecium strains were assigned to seven STs (ST78, ST412, ST478, ST792, ST896, ST987, ST963) that belonged to CC17. The E. faecalis sequenced belonged to ST9 (CC9). Conclusion E. faecium was predominant, and infection isolates were more virulent than colonization isolates and harboured more often the gene gelE. Infections caused by VRE carrying the asa1 gene appeared to be associated with a fatal outcome.

Background Carbapenems resistance in Enterobacter spp. has increased in the last decade, few studies, however, described the mechanisms of resistance in this bacterium. This study evaluated clonality and mechanisms of carbapenems resistance in clinical isolates of Enterobacter spp. identified in three hospitals in Brazil (Hospital A, B and C) over 7-year. Methods Antibiotics sensitivity, pulsed-field gel electrophoresis (PFGE), PCR for carbapenemase and efflux pump genes were performed for all carbapenems-resistant isolates. Outer-membrane protein (OMP) was evaluated based on PFGE profile. Results A total of 130 isolates of Enterobacter spp were analyzed, 44/105 (41, 9%) E. aerogenes and 8/25 (32,0%) E. cloacae were resistant to carbapenems. All isolates were susceptible to fosfomycin, polymyxin B and tigecycline. KPC was present in 88.6% of E. aerogenes and in all E. cloacae resistant to carbapenems. The carbapenems-resistant E. aerogenes identified in hospital A belonged to six clones, however, a predominant clone was identified in this hospital over the study period. There is a predominant clone in Hospital B and Hospital C as well. The mechanisms of resistance to carbapenems differ among subtypes. Most of the isolates co-harbored blaKPC, blaTEM and /or blaCTX associated with decreased or lost of 35–36KDa and or 39 KDa OMP. The efflux pump AcrAB-TolC gene was only identified in carbapenems-resistant E. cloacae. Conclusions There was a predominant clone in each hospital suggesting that cross-transmission of carbapenems-resistant Enterobacter spp. was frequent. The isolates presented multiple mechanisms of resistance to carbapenems including OMP alteration.

Health care associated infections (HAIs) are currently among the major challenges to the care of hematopoietic stem cell transplantation (HSCT) patients. The objective of the present study was to evaluate the impact of 2% chlorhexidine (CHG) bathing on the incidence of colonization and infection with vancomycin-resistant Enterococcus (VRE), multidrug-resistant (MDR) gram-negative pathogens, and to evaluate their CHG minimum inhibitory concentration (MIC) after the intervention. A quasi-experimental study with duration of 9 years was conducted. VRE colonization and infection, HAI rates, and MDR gram-negative infection were evaluated by interrupted time series analysis. The antibacterial susceptibility profile and mechanism of resistance to CHG were analyzed in both periods by the agar dilution method in the presence or absence of the efflux pump inhibitor carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) and presence of efflux pumps (qacA/E, qacA, qacE, cepA, AdeA, AdeB, and AdeC) by polymerase chain reaction (PCR). The VRE colonization and infection rates were significantly reduced in the postintervention period (P = 0.001). However, gram-negative MDR rates in the unit increased in the last years of the study. The CHG MICs for VRE increased during the period of exposure to the antiseptic. A higher MIC at baseline period was observed in MDR gram-negative strains. The emergence of a monoclonal Pseudomonas aeruginosa clone was observed in the second period. Concluding, CHG bathing was efficient regarding VRE colonization and infection, whereas no similar results were found with MDR gram-negative bacteria.