Methicillin resistance in Staphylococcus aureus strains isolated from food and wild animal carcasses in Italy.

Following the detection of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in food-producing animals, both livestock and wildlife, and derived products, are considered potential sources of MRSA in humans. There is a paucity of data on MRSA in foods in Italy, and the data regarding wild animals are particularly scarce. A total of 2162 food samples collected during official monitoring activities in 2008 were analyzed for the detection of S. aureus. Also, samples from 1365 wild animals collected by the National Reference Center for Wild Animal Diseases in 2003-2009 were subjected to anatomopathological examination. S. aureus isolates were processed for phenotypic and molecular methicillin resistance determinations. S. aureus was found in 2.0% of wild animal carcasses and in 3.2% of wild boar lymph nodes: none showed methicillin resistance. The prevalence of S. aureus in food was 17.1%. Two MRSA strains, both from bulk tank milk (prevalence 0.77%) were isolated: the strains were resistant to tetracycline, had spa-type t899, and were negative for the Panton-Valentine leukocidin gene. The low prevalence of MRSA suggests that the risk of transmission to humans via food is limited. However, attention should be paid to the cattle food chain, which may be a potential route of transmission of LA-MRSA.

The effect of inappropriate therapy on bacteremia by ESBL-producing bacteria.

OBJECTIVE: To describe the impact of empiric appropriate treatment and the risk factors associated with mortality in patients with bacteremia by E. coli, K. pneumoniae and P. mirabilis producing ESBL. METHODS: Data were reviewed in an 8-year retrospective study, and 128 bacteremias were found: 80 caused by E. coli (62.5%), 28 by K. pneumoniae (21.9%) and 20 by P. mirabilis (18.6%). RESULTS: The initial antibiotic treatment, administered within 72 h after the first positive blood culture, was appropriate with carbapenems or other antimicrobial agents with documented in vitro sensitivity in 53.8 and 16% of patients, respectively. The overall mortality 21 days after diagnosis was 17.2%, and it was 14.9 and 35.2% for patients adequately and inadequately treated, respectively. At univariate analysis the p value for mortality with and without appropriate treatment was 0.05, and significant differences were found only for previous positive blood cultures (p = 0.004) and presence of septic shock at diagnosis (p = 0.006). CONCLUSION: In this case series there was a high rate of initial appropriate empiric treatment, and only a marginal impact on mortality was found with regard to appropriate and inappropriate treatment. This report shows that the knowledge of ESBL-producing characteristics varies widely among the different case series for reasons that still have to be clarified.

Use of a T-cell-based test for detection of tuberculosis infection among immunocompromised patients.

The aim of this study was to compare the performance of the T-SPOT.TB test, a T-cell-based test, with the tuberculin skin test (TST) in the diagnosis of latent tuberculosis (TB) infection. The study was carried out in 138 immunosuppressed haematology patients who had been nosocomially exposed to a case of smear-positive TB. Overall, 44.2% of the contacts were positive by T-SPOT.TB test, and 17.4% by TST (concordance 67.8%). The apparent prevalence of infection fell from 25.9 to 14.5% with the TST with increasing immunosuppression, although this difference was not significant. In contrast, the apparent prevalence of infection with the T-SPOT.TB test was unaffected at 44.6 and 44.3%, respectively. The T-SPOT.TB test had an overall indeterminate rate of 4.3%, and this was also unaffected by the level of immunosuppression. This study suggests that the T-SPOT.TB test maintains its sensitivity and performance in immunocompromised patients, identifying a large number of truly infected patients anergic to the tuberculin skin test.