Dissemination of bla OXA-370 gene among several Enterobacteriaceae species in Brazil.

OXA-370 is a recently described OXA-48 variant that has only been described in a few Enterobacter spp. and Klebsiella pneumoniae isolates. The purpose of this study is to assess the prevalence of OXA-370-producing isolates in carbapenem-nonsusceptible Enterobacteriaceae recovered from 28 hospitals from Brazil. Real-time PCR was used to determine the presence of bla NDM-1, bla KPC-2, bla VIM-type, bla GES-type, bla OXA-48-like, and bla IMP-type genes. A total of 4,451 Enterobacteriaceae were screened. The gene bla OXA-48-like was detected in 74 (2.5%) isolates, mostly of Enterobacter spp. (44.6% E. cloacae and 2.7% E. aerogenes) and Klebsiella spp. (31.1% K. pneumoniae and 6.7% K. oxytoca), followed by Escherichia coli, (6.7%), Morganella morganii, (2.7%), Citrobacter freundii (1.3%), Proteus mirabilis (1.3%), Providencia stuartii (1.3%), and Serratia spp. (1.3%). These isolates were from five hospitals, 67 (90.5%) from the hospital where the bla OXA-370 was first described. Sequencing of bla OXA-48-like was performed in 52 isolates, including E. cloacae, E. aerogenes, K. pneumoniae, K. oxytoca, E. coli, and C. freundii; all presenting 100% identity with bla OXA-370. PFGE revealed the presence of distinct clones among K. pneumoniae, E. cloacae, K. oxytoca, and E. coli. Susceptibility rates to meropenem, imipenem, and ertapenem among OXA-370-producing isolates were 92.3%, 78.8%, 7.7% respectively; the MIC50 /MIC90 were 0.38/2 mg/L and 1/3 mg/L for meropenem and imipenem respectively. Overall, antimicrobial susceptibility analysis suggests that OXA-370 lacks carbapenemase activity. Our study demonstrated that the bla OXA-370 gene is disseminated among several Enterobacteriaceae species and clones, indicating a high potential for dissemination.

Lactobacillus rhamnosus bacteremia in a kidney transplant recipient.

Lactobacillus rhamnosus is a rare clinical pathogen. A case of bacteremia caused by L. rhamnosus in a kidney transplant recipient is described. Once considered only as a contaminant or a low-virulence organism, L. rhamnosus might be an opportunistic pathogen in immunocompromised patients. To our knowledge, this is the first report of primary bloodstream infection caused by L. rhamnosus in a kidney transplant recipient.

PCR to detect Mycobacterium tuberculosis in respiratory tract samples: evaluation of clinical data.

Tuberculosis (TB) remains as an important public health problem worldwide. Therefore, the rapid detection of M. tuberculosis is of primary importance to effectively reduce transmission in patients. The aims of this study were to evaluate two in-house molecular tests: nested PCR (nPCR) and real-time PCR (rtPCR) to detect M. tuberculosis complex directly from clinical samples. The results were compared to the culture results and to the culture results plus clinical data of patients. The rtPCR and nPCR presented high sensitivity (Se) and specificity (Sp) (rtPCR 97·6% and 91·5%, nPCR 85·7% and 92·7%, respectively) compared to culture. When the results of the molecular tests were compared to the culture plus clinical data the Se and Sp were 90·2% and 97·3% for rtPCR and 80·4% and 98·6% for the nPCR, respectively. The results demonstrated that molecular assays of M. tuberculosis can provide a sensitive and rapid diagnostic of TB, and when used in addition to the clinical data of TB patients will help to improve the Sp of the diagnosis of pulmonary TB.

Comparison of polymyxin B with other antimicrobials in the treatment of ventilator-associated pneumonia and tracheobronchitis caused by Pseudomonas aeruginosa or Acinetobacter baumannii.

PURPOSE: This study was designed to compare the efficacy of polymyxin B with other antimicrobials in the treatment of ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT) by Pseudomonas aeruginosa or Acinetobacter baumannii. METHODS: A prospective cohort study was performed. Patients >18 years of age with the diagnosis of VAP or VAT who received appropriate therapy for >48 h were analyzed. The primary outcome was 30-day mortality. Clinical covariates were assessed and compared between the groups. RESULTS: A total of 67 episodes were analyzed: 45 (67 %) treated with polymyxin B and 22 (33 %) with comparators. The crude 30-day mortality was 53 % (24 of 45) in the polymyxin B group and 27 % (6 of 22) in the comparator group (P = 0.08). Multivariable analysis using Cox regression models indicated that polymyxin B treatment was independently associated with increased mortality. CONCLUSIONS: Polymyxin B treatment in the currently recommended dosage may be inferior to other drugs in the treatment of VAP and VAT caused by organisms tested as susceptible in vitro to this agent.

Risk factors for 30-day mortality in patients with carbapenem-resistant Acinetobacter baumannii during an outbreak in an intensive care unit.

This study assessed risk factors for 30-day mortality in 66 patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infection or colonization during an outbreak in an intensive-care unit. Clinical and demographic characteristics were evaluated. The overall 30-day mortality was 47·0%. In the multivariate Cox regression model, septic shock [adjusted hazard ratio (aHR) 5·01, 95% confidence interval (CI) 2·32-10·01] and APACHE II score at onset of infection (aHR 1·11, 95% CI 1·04-1·18) were significantly associated with 30-day mortality. Administration of appropriate therapy was a protective factor, but it was not statistically significant (aHR 0·48, 95% CI 0·21-1·12). A sample of isolates tested (n=27) carried the blaOXA-23 gene. Severity of baseline condition and severity of infection presentation were major risk factors for mortality during the outbreak. Patients who received appropriate therapy tended to have lower mortality rates, although therapy was started late and dosage was suboptimal in most cases.

Mycobacterium tuberculosis resistance in HIV-infected patients from a tertiary care teaching hospital in Porto Alegre, southern Brazil.

Drug-resistant Mycobacterium tuberculosis isolates are a major public health concern worldwide. There are few studies assessing tuberculosis (TB) resistance in Brazil. This study assessed the prevalence of resistance to the five first-line anti-TB drugs in TB isolates from HIV-infected patients in a tertiary care teaching hospital in southern Brazil. From September 1997 to July 2003, 398 TB complex isolates were included in the study. Resistance to one or more first-line anti-TB drugs was found in 71 (17.8%) of patients and was significantly more frequent among previously treated patients (12 [30.8%] of 39 patients) than new cases (59 [16.4%] of 359) (P=0.05). The highest resistance rates were found to isoniazid (9.9% overall; and 25.6% among previously treated patients). Multidrug-resistant TB was found in eight (2.0%) patients, with higher rates among previously treated patients than new cases: two (5.1%) patients vs. six (1.6%), respectively (P=0.18). Multidrug resistance and particularly isoniazid resistance rates among previously treated HIV patients are of great concern. Our findings indicate the need to reappraise regional TB treatment policies and support the recommendation for routine performance of in vitro TB susceptibility tests in all previously treated patients.

Risk factors for imipenem-resistant Pseudomonas aeruginosa: a comparative analysis of two case-control studies in hospitalized patients.

Risk factors for acquisition of imipenem-resistant Pseudomonas aeruginosa by hospitalized patients were assessed at a tertiary care hospital. Two case-control studies with different control groups were used. In Study 1, patients with imipenem-resistant P. aeruginosa (IRPA) (case group) were compared with patients selected at random from the same unit. In Study 2, the case group was compared with patients with imipenem-susceptible P. aeruginosa (ISPA). Ninety-three patients with IRPA and 93 control patients were included in Study 1, and 93 IRPA patients and 65 patients with ISPA were included in Study 2. Carbapenem treatment [odds ratio (OR) 5.82], mechanical ventilation (OR 3.22) and hospital admission in the previous year (OR 2.59) were associated with IRPA in Study 1. An interaction between carbapenem and vancomycin was found to be a significant risk factor for IRPA (OR for carbapenem in patients with vancomycin use 43.71). In Study 2, carbapenem exposure (OR 12.82) and renal failure (OR 5.00) were associated with IRPA. Our study confirmed that carbapenem exposure is the main risk factor for IRPA, and found that the use of both carbapenem and vancomycin can increase this effect.

Dissemination of Pseudomonas aeruginosa producing SPM-1-like and IMP-1-like metallo-beta-lactamases in hospitals from southern Brazil.

BACKGROUND: Metallo-beta-lactamase (MBL) is an emerging resistance mechanism among Pseudomonas aeruginosa. The prevalence of this mechanism is particularly high in Latin America. We aimed to describe the prevalence and molecular characteristics of SPM-1-like, IMP-1-like and VIM type MBLs among ceftazidime and/or imipenem-resistant nosocomial P. aeruginosa isolates. METHODS: Pseudomonas aeruginosa isolates resistant to ceftazidime and/or imipenem recovered from hospitalized patients from two teaching hospitals from Porto Alegre, Brazil, were prospectively selected. Isolates were tested for MBL production using two phenotypic screening tests. Those isolates with positive results were further tested for the presence of MBL genes (SPM-1-like, IMP-1-like and VIM type) and submitted to molecular typing. RESULTS: A total of 92 isolates were analyzed and 33 (35.9%) were presumptively MBL producers by phenotypic tests. The SPM-1-like gene was found in 18 isolates and IMP-1-like in 5 isolates. In ten isolates the MBL type could not be identified. Three IMP-1-like isolates were susceptible to imipenem. SPM-1-like isolates comprised a single clone, and IMP-1-like isolates another single clone. CONCLUSION: The prevalence of MBL production among ceftazidime-resistant P. aeruginosa isolates is relatively high in both hospitals. Infection control measures have been challenged and further improvements in such measures are required to prevent dissemination of these isolates among hospitals. This is the first report of IMP-1-like MBLs in P. aeruginosa in southern Brazil.

High prevalence of metallo-beta-lactamase-mediated resistance challenging antimicrobial therapy against Pseudomonas aeruginosa in a Brazilian teaching hospital.

The prevalence of metallo-beta-lactamase (MBL) production among Pseudomonas aeruginosa nosocomial isolates from a Brazilian teaching hospital was determined. A total of 512 P. aeruginosa isolates were recovered from 245 patients during a 10-month period. Ninety-four (38.4%, 95% CI 32.2-44.8%) isolates were MBL producers. Most resistance to beta-lactams was mediated by MBL. Forty-one (16.7%) were resistant to all drugs except polymyxin B and 33 (80.5%) of these were MBL producers. Clonal dissemination, documented by DNA macrorestriction, played a major role for the spread of MBL isolates. The blaSPM-1 gene was demonstrated by PCR in 14 randomly selected MBL isolates. The extremely high prevalence of MBL production found challenges the choice of therapeutics for P. aeruginosa, and measures to control horizontal dissemination of MBL producers are urgently required.