Emergence of Acinetobacter baumannii ST730 carrying the blaOXA-72 gene in Brazil

Over the last decade, Acinetobacter baumannii resistant to carbapenems has emerged in many medical centres and has been commonly associated with high morbimortality. In Brazil, this resistance is mainly attributed to the spread of OXA-23-producing clones and, to a lesser extent, to OXA-143-producing clones. Here, we describe, for the first time, two OXA-72-producing A. baumannii isolates in southern Brazil to a broad spectrum of antibiotics, except polymyxin B and tigecycline. Molecular typing by multilocus sequence typing (MLST) demonstrated that both OXA-72-producing isolates belong to a new sequence type (ST), ST730, which was recently identified in OXA-23-producing A. baumannii isolates in São Paulo, Brazil. We demonstrate that the two A. baumannii ST730 isolates carrying blaOXA-72share a common ancestral origin with the blaOXA-23producers in Brazil. This observation reinforces the importance of strain-typing methods in order to clarify the dynamics of the emergence of new clones in a geographic region.

Clinical characteristics of 1,260 patients during an outbreak of carbapenem-resistant Acinetobacter spp. in Porto Alegre, Brazil

Background: Over the last decade, Acinetobacter baumannii has been an important cause of nosocomial infections worldwide.Aim: To assess clinical and epidemiological characteristics of patients during a large citywide outbreak of carbapenem-resistant A. baumannii (CRAB). Methods: Retrospective cross-sectional study that evaluated the information obtained from the official notification system for CRAB within the Municipal Health Department, Porto Alegre, Brazil, in the period of July 1st, 2007 to December 31st,2008.Results: A total of 1,260 CRAB from infection (608 [48.3%]) or colonization (652[51.7%]) were reported in 18 hospitals. Most patients (53.5%) were hospitalized at intensive care units and have been exposed to invasive procedures, but 757 (60.7%)patients had no underlying comorbidity reported. A total of 1,143 (90.7%) patients received some antimicrobial 90 days before CRAB detection and 36.4% received a carbapenem. Data on the outcome were available for 618 (49.0%) patients and 54.3% of them died. Infection was significantly more common in patients admitted to public hospitals; with trauma, with exposure to antibiotics in the previous 90 days, and in patients submitted to invasive procedures. Conclusion: This study suggests that in the context of an outbreak, baseline comorbidities and previous carbapenem exposure may be less important risk factors for CRAB infection/colonization.

Nosocomial and community infections due to class A extended-spectrum β-lactamase (ESBLA)-producing Escherichia coli and Klebsiella spp. in southern Brazil

OBJECTIVES: To determine the prevalence of class A extended spectrum β-lactamases (ESBL)-producing Escherichia coli and Klebsiella spp., and to investigate clonality among ESBL-producing isolates of nosocomial and community infections. METHODS: The study involved 354 nosocomial infections samples and 992 community infections samples, obtained between 2003 and 2006 at Caxias do Sul, RS. The detection of ESBL was performed by the disk-diffusion test. Presence of blaCTX-M, blaSHV and blaTEM β-lactamase genes was evaluated by PCR, and genomic typing was determined by pulsed-field gel electrophoresis analysis. RESULTS: Higher frequency of ESBL-producing isolates were detected among nosocomial samples of E. coli (6.7 percent) and Klebsiella (43.7 percent), than those obtained from community infections (0.4 percent and 2.6 percent). blaTEM and blaCTX were the most prevalent ESBL gene families in both E. coli and Klebsiella isolates. Different pulsotypes were obtained among ESBL-producing E. coli and 11 clones for Klebsiella spp., which occurred over the years and in different hospital wards. Among ESBL-producing K. pneumoniae, 74.3 percent transferred ESBL genes by conjugation and exhibited concomitant decreased aminoglycosides susceptibility. CONCLUSION: ESBL-producing E. coli, and especially K. pneumoniae are essentially a nosocomial problem, and their dissemination to the community is relatively limited. The great genetic variability observed among ESBL-producing bacteria indicates polyclonal spread and high transference of ESBL genes between bacteria in the hospital environment. This information is of paramount importance for nosocomial infection control.

Evaluation of the in vitro activity of two fourth-generation cephalosporins against bacterial samples isolated from patients in several Brazilian Hospitals

Cefpirome and cefepime are two fourth-generation cephalosporins recently introduced in Brazil. They have a very similar range of in vitro antimicrobial activity, but some differences have been noticed. The goal of this study was to compare the in vitro activity of cefpirome and cefepime against bacterial samples isolated in Brazilian hospitals. We studied 931 samples taken from hospitalized patients between April and June, 1998. The minimum inhibitory concentration (MIC) was determined by the Etest method. The potency of cefpirome was similar to that of cefepime, except against enterococci and coagulase-negative staphylococci, where cefpirome proved 2-fold more potent. The MICs90 for cefepime were inferior to cefpirome in response to Klebsiella pneumoniae (MICs90, 24 and 96µg/mL, respectively), Pseudomonas aeruginosa (MICs90, 48 and 128µg/mL, respectively), and other Gram-negative organisms (MICs90, 64 and 256µg/mL, respectively). Despite the fact that cefpirome presented a slightly broader range of action against Gram-positive bacteria(90 percent sensitive vs. 78 percent sensitive to cefepime), and that cefepime presented an equally broad range against Gram-negative bacteria (74 percent sensitive vs. 65 percent sensitive to cefpirome), these differences were not considered clinically significant because the sensitivity differed in MIC by less than 2 dilutions. Only 16 (1.7 percent) of the 931 samples tested showed a significant difference in sensitivity. This study suggests that, except for Acinetobacter sp. and P. aeruginosa, laboratories may routinely test only cefpirome and apply the same category result to cefepime. Since category discrepancies are very rare and cefpirome is slightly less active than cefepime against Enterobacteriaceae, isolates susceptible to cefepime will certanly also be susceptible to cefpirome. To optimize the treatment of severely infected patients, especially where species such as Acinetobacter sp and P. aeruginosa are involved, we recommend that both cephalosporins be tested by using the same susceptibility test method to determine the MIC.