Adherence ability and serum resistance of different hospital clusters of Acinetobacter baumannii.

The role of mechanical ventilation and catheters in favouring Acinetobacter baumannii infections needs to be better understood. This study evaluated the adherence of 19 isolates of different hospital clusters of A. baumannii to abiotic surfaces and epithelial cells (HEp-2). Of the hydrophobic isolates, 80% adhered to polystyrene, indicating a close relationship between hydrophobicity and adherence. All isolates adhered to epithelial cells to different degrees, and 73·7% showed an aggregated pattern. Analysis of the serum resistance of catheter-tip isolates showed that all were resistant. These worrisome results showed that the high capacity of A. baumannii to adhere to surfaces and survive in human serum could hinder treatment and control of this pathogen.

Survival of vancomycin-intermediate Staphylococcus aureus on hospital surfaces.

BACKGROUND: Contaminated surfaces play an important role in the transmission of certain pathogens that are responsible for healthcare-associated infections. Although previous studies have shown that meticillin-resistant Staphylococcus aureus (MRSA) can survive on dry surfaces at room temperature, no published data regarding vancomycin-intermediate S. aureus (VISA) are available to date. AIM: To compare the survival time on different types of surfaces, cell-surface hydrophobicity, adherence to abiotic surfaces and biofilm formation of meticillin-susceptible S. aureus (MSSA), MRSA and VISA. METHODS: Survival of the S. aureus strains was tested on latex, cotton fabric, vinyl flooring and formica. Cell-surface hydrophobicity was determined using the hydrocarbon interaction affinity method. Adhesion to abiotic surfaces was tested on granite, latex (gloves), glass, vinyl flooring and formica. Biofilm formation was evaluated at 6, 12, 24 and 48 h. FINDINGS: All of the samples survived on the vinyl flooring and formica for at least 40 days. VISA survived on both surfaces for more than 45 days. All of the strains were highly hydrophobic. VISA adhered to latex, vinyl flooring and formica. Biofilm formation increased for all of the tested strains within 6-24 h. CONCLUSION: VISA present high survival, adherence and cell-surface hydrophobicity. Therefore, as the treatment of patients with VISA is a significant challenge for clinicians, greater care with cleaning and disinfection of different types of surfaces in healthcare facilities is recommended because these may become important reservoirs of multi-resistant pathogens.

Plasmid-mediated quinolone resistance (PMQR) and mutations in the topoisomerase genes of Salmonella enterica strains from Brazil.

The objective of this study was to identify mutations in the Quinolone Resistance Determining sources Regions (QRDR) of the gyrA, gyrB, parC, and parE genes and to determine if any of the qnr variants or the aac(6')-Ib-cr variant were present in strains of Salmonella spp. isolated in Brazil. A total of 126 Salmonella spp. strains from epidemic (n = 114) and poultry (n = 12) origin were evaluated. One hundred and twelve strains (88.8%) were resistant to nalidixic acid (NAL) and 29 (23.01%) showed a reduced susceptibility to ciprofloxacin (Cip). The mutations identified were substitutions limited to the QRDR of the gyrA gene in the codons for Serine 83, Aspartate 87 and Alanine 131. The sensitivity to NAL seems to be a good phenotypic indication of distinguishing mutated and non-mutated strains in the QRDR, however the double mutation in gyrA did not cause resistance to ciprofloxacin. The qnrA1 and qnrB19 genes were detected, respectively, in one epidemic strain of S. Enteritidis and one strain of S. Corvallis of poultry origin. Despite previous detection of qnr genes in Brazil, this is the first report of qnr gene detection in Salmonella, and also the first detection of qnrB19 gene in this country. The results alert for the continuous monitoring of quinolone resistance determinants in order to minimize the emergence and selection of Salmonella spp. strains showing reduced susceptibility or resistance to quinolones.

Plasmid-mediated quinolone resistance (PMQR) and mutations in the topoisomerase genes of Salmonella enterica strains from Brazil

The objective of this study was to identify mutations in the Quinolone Resistance Determining sources Regions (QRDR) of the gyrA, gyrB, parC, and parE genes and to determine if any of the qnr variants or the aac(6')-Ib-cr variant were present in strains of Salmonella spp. isolated in Brazil. A total of 126 Salmonella spp. strains from epidemic (n = 114) and poultry (n = 12) origin were evaluated. One hundred and twelve strains (88.8%) were resistant to nalidixic acid (NAL) and 29 (23.01%) showed a reduced susceptibility to ciprofloxacin (Cip). The mutations identified were substitutions limited to the QRDR of the gyrA gene in the codons for Serine 83, Aspartate 87 and Alanine 131. The sensitivity to NAL seems to be a good phenotypic indication of distinguishing mutated and nonmutated strains in the QRDR, however the double mutation in gyrA did not cause resistance to ciprofloxacin. The qnrA1 and qnrB19 genes were detected, respectively, in one epidemic strain of S. Enteritidis and one strain of S. Corvallis of poultry origin. Despite previous detection of qnr genes in Brazil, this is the first report of qnr gene detection in Salmonella, and also the first detection of qnrB19 gene in this country. The results alert for the continuous monitoring of quinolone resistance determinants in order to minimize the emergence and selection of Salmonella spp. strains showing reduced susceptibility or resistance to quinolones.

Antimicrobial efficacy of alcohol-based hand gels with a 30-s application.

AIMS: The objective of this study was to assess the antimicrobial efficacy of alcohol-based hand gels according to European Norm 1500 (EN 1500). METHODS AND RESULTS: We assessed the antimicrobial efficacy of 12 alcohol-based hand gels produced in Brazil, containing 70% w/w or v/v ethyl alcohol as the active ingredient, according to EN 1500, with a 30-s application. In addition, 70% w/w ethyl alcohol and three alcohol-based hand rubs commonly used in Europe and effective according to EN 1500 were also tested. Eight of 12 (67%) alcohol-based hand gels produced in Brazil failed by EN 1500. In contrast, 70% w/w ethyl alcohol and European alcohol-based hand rubs were approved by EN 1500. CONCLUSIONS: In this study, the majority of Brazilian alcohol-based hand gels showed limited efficacy on hand hygiene within 30 s. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings of this study may be used as an important argument to motivate Brazilian manufacturers to improve the antimicrobial efficacy of alcohol-based hand gels, because it is prudent to suppose that alcohol-based hand gels can be recommended for use in healthcare settings only if they show antimicrobial activity at least similar to that of alcohol-based liquid preparations, including the traditional 70% w/w ethyl alcohol.

Evolution of antimicrobial resistance of Acinetobacter baumannii in a university hospital.

AIMS: To investigate the susceptibility pattern and the molecular epidemiology of Acinetobacter baumannii isolates in two periods (1994-1996 and 2004-2007) in Londrina University Hospital. METHODS AND RESULTS: Antimicrobial susceptibility of 150 A. baumannii isolates was assessed by disc diffusion and agar dilution methods. Genetic similarity amongst the isolates was evaluated by ERIC-PCR. Resistance of A. baumannii to carbapenems increased from 2% (1994-1996) to 73% (2004-2007). Thirty-eight clones were detected. CONCLUSIONS: The results of the study suggest that the high prevalence of carbapenem resistance amongst Acinetobacter baumannii organisms in this institution is not caused by the spread of a predominant clone. SIGNIFICANCE AND IMPACT OF THE STUDY: This work reinforces the importance monitoring antimicrobial susceptibility rates.

Prevalence and genetic characterization of blaCTX-M among Klebsiella pneumoniae isolates collected in an intensive care unit in Brazil.

Thirteen (44.8%) CTX-M-2-producing K. pneumoniae clinical isolates were identified among 29 strains collected from single patients with serious infection hospitalized in an intensive care unit of a tertiary hospital located in São Paulo, Brazil. These isolates belonged to 9 different typing clusters and showed great diversity of plasmid content. Their bla(CTX-M-2)was carried in an ISCR1/sul1-type integron structure located in transferable plasmids of different sizes or in the chromosome.

In vitro evaluation of the antimicrobial activity of meropenem in combination with polymyxin B and gatifloxacin against Pseudomonas aeruginosa and Acinetobacter baumannii.

The antimicrobial activity of meropenem combined with either polymyxin B or gatifloxacin was evaluated by the checkerboard method against Pseudomonas aeruginosa (10 strains) and Acinetobacter baumannii (10 strains). In addition, the triple combination of polymyxin B, gatifloxacin, and meropenem was also studied as well as the polymyxin B and gatifloxacin combination. A partial synergism interaction between meropenem and polymyxin B was observed for 80% of the A. baumannii strains. In contrast, this combination showed an indifferent effect for 80% of the P. aeruginosa strains tested. The combination of meropenem and gatifloxacin showed synergism only for two strains of A. baumannii, and partial synergism and additive effect for seven strains and indifference for four strains of both species. For the strains of P. aeruginosa, the double combination of polymyxin B and gatifloxacin and the triple combination of meropenem, polymyxin B and gatifloxacin were indifferent for the majority of the strains tested, that is, 90 and 80% respectively.

Atypical phenotypic characteristics of klebsiella pneumoniae isolates from an outbreak in a neonatal intensive care unit in Brazil

Extended-spectrum beta-Lactamase-producing (ESBL) Klebsiella sp.isolates from an outbreak in a Neonatal Intensive Care Unit (NICU) at a teaching hospital in Londrina, Paraná State, Brazil, presented atypical phenotypic characteristics that hampered their identification and the distinction between Klebsiella and Enterobacter species. Ten isolates were identified as K. pneumoniae due to negative reactions for motility and inducible beta-lactamase test (ESBL and AmpC) despite being positive for ornithyne descarboxilase. These isolates were genotyped by ribotyping and polymerase chain reaction (PCR) with repetitive extragenic palindromic sequences (REP). Ribotyping by means of an automated instrument and EcoRI and Pvu II as restriction enzymes resulted indetection of K. pneumoniae subspecie pneumoniae RIBO1 222-36-S-5 ribotype. Typing by REP-PCR showed that the 17 isolates from the outbreak were highly similar, belonging to one cluster with 100 percent of similarity, and that they presented more than 70 percent of similarity with K. pneumoniae ATCC 13883 and ATCC 10031, and 25 percent of similarity with E. aerogenes CDC 1680. In conclusion, the isolates of the outbreak were identified as Klebsiella pneumoniae, despite presenting ornithyne descarboxilase enzyme, which is an atypical characteristic of this Klebsiella species.

Isolados de Klebsiella sp. produtora de beta-lactamase de espectro estendido (ESBL), responsável por um surto na Unidade Neonatal de Terapia Intensiva (UNTI) do Hospital Universitário de Londrina, Paraná, Brasil apresentaram características fenotípicas atípicas que dificultaram sua identificação e a diferenciação entre as espécies Klebsiella pneumoniae e Enterobacter aerogenes. Dez isolados foram identificados como K. pneumoniae devido às reações negativas para motilidade e produção de enzimas beta-lactamases (ESBL e AmpC). Embora apresentassem teste positivo para ornitina descarboxilase. Estes isolados foram genotipados por ribotipagem e por reação em cadeia da polimerase (PCR) com oligonucleotídeos para "repetitive extragenic palindromic sequences" (REP). A ribotipagem com as enzimas de restrição EcoRI e Pvu II detectou o ribotipo de K. pneumoniae subespécie pneumoniae RIBO1 222-36-S-5. A técnica de REP-PCR mostrou que os isolados do surto foram similares, pertencentes a um grupo com 100 por cento de similaridade, e apresentaram mais de 70 por cento de similaridade com amostras padrão de K. pneumoniae (ATCC 13883 e 10031), e 25 por cento de similaridade com E. aerogenes CDC 1680. Concluindo, os isolados do surto da NICU mostraram se geneticamente relacionados e foram identificados como Klebsiella pneumoniae, embora apresentassem ornitina descarboxilase, característica atípica para esta espécie de Klebsiella.