Antibiotic-Induced Pathobiont Dissemination Accelerates Mortality in Severe Experimental Pancreatitis.

Although antibiotic-induced dysbiosis has been demonstrated to exacerbate intestinal inflammation, it has been suggested that antibiotic prophylaxis may be beneficial in certain clinical conditions such as acute pancreatitis (AP). However, whether broad-spectrum antibiotics, such as meropenem, influence the dissemination of multidrug-resistant (MDR) bacteria during severe AP has not been addressed. In the currently study, a mouse model of obstructive severe AP was employed to investigate the effects of pretreatment with meropenem on bacteria spreading and disease outcome. As expected, animals subjected to biliopancreatic duct obstruction developed severe AP. Surprisingly, pretreatment with meropenem accelerated the mortality of AP mice (survival median of 2 days) when compared to saline-pretreated AP mice (survival median of 7 days). Early mortality was associated with the translocation of MDR strains, mainly Enterococcus gallinarum into the blood stream. Induction of AP in mice with guts that were enriched with E. gallinarum recapitulated the increased mortality rate observed in the meropenem-pretreated AP mice. Furthermore, naïve mice challenged with a mouse or a clinical strain of E. gallinarum succumbed to infection through a mechanism involving toll-like receptor-2. These results confirm that broad-spectrum antibiotics may lead to indirect detrimental effects during inflammatory disease and reveal an intestinal pathobiont that is associated with the meropenem pretreatment during obstructive AP in mice.

Molecular characterization and resistance profile of Salmonella Enteritidis PT4 and PT9 strains isolated in Brazil.

A total of 41 Salmonella Enteritidis strains, including phago-types (PTs) PT4 and PT9, were characterized by antimicrobial resistance profiles and PFGE. Of these strains, 34 were isolated from patients and foods, and 7 were of poultry origin. All strains were susceptible to ampicillin, chloramphenicol, cefotaxime, ciprofloxacin and trimethoprim/sulfamethoxazole, and 41.5 % (n = 17) were resistant to nalidixic acid. PFGE analysis using XbaI and SpeI restriction enzymes resulted in X1S1 as the prevalent pattern, which was present in 48.8 % (n = 20) of epidemic strains and in one strain isolated from discarded hatching eggs. Distinct patterns were found for the other strains isolated from poultry (X3S1, X8S8, X11S12, X11S13, X16S1 and X13S15). The S. Enteritidis PT9 strains associated with outbreaks of salmonellosis were highly similar (≥0.90), suggesting clonality. The PFGE genotypes were related to the PTs, and it was possible to differentiate strains isolated from patients with salmonellosis from other strains of non-epidemic origin. The PFGE results suggested that the S. Enteritidis strains of poultry origin were a possible source of human salmonellosis during the study period.

Phenotypic and genotypic characterization of group B streptococcal isolates in southern Brazil.

One-hundred sixty-eight group B streptococcal (GBS) isolates from a Brazilian hospital were phenotypically and genotypically characterized. Isolates were recovered from human sources from April 2006 to May 2008 and classified as either invasive, noninvasive, or colonizing isolates. Classical methods for serotyping and antibiotic resistance profiling were employed. Clonal groups were also defined by pulsed-field gel electrophoresis (PFGE). Results showed that susceptibility to beta-lactam antimicrobials was predominant among the isolates. Only 4.7% were resistant to erythromycin and clindamycin. The erm(B) gene was widely detected in our GBS isolates, according to our phenotypic results (constitutive macrolide-lincosamide-streptogramin B [cMLSB] resistance phenotype), and the erm(A) gene was also detected in some isolates. MLSB resistance was restricted to strains isolated from patients with noninvasive infections and carriers. Serotype Ia was predominant (38.1%), serotype IV isolates were found at a high frequency (13.1%), and few isolates of serotype III were identified (3%). Pulsed-field gel electrophoresis results revealed a variety of types, reflecting the substantial genetic diversity among GBS strains, although a great number of isolates could be clustered into two major groups with a high degree of genetic relatedness. Three main PFGE clonal groups were found, and isolates sharing the same PFGE type were grouped into different serotypes. Furthermore, in a few cases, isolates from the same patients and possessing the same PFGE type were of different serotypes. These findings could be related to the occurrence of capsular switching by horizontal transfer of capsular genes.