Mastitis adversely affects milk production and in general cows do not regain their full production levels post recovery, leading to considerable economic losses. Moreover the percentage decrease in milk production depends on the specific pathogen that caused the infection and enterobacteria are responsible for this greater reduction. Phenotypic tests are among the currently available methods used worldwide to identify enterobacteria; however they tend to misdiagnose the species despite the multiple tests carried out. On the other hand The Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) technique has been attracting attention for its precise identification of several microorganisms at species level. In the current study, 183 enterobacteria were detected in milk (n = 47) and fecal samples (n = 94) from cows, and samples from water (n = 23) and milk lines (n = 19). All these samples were collected from a farm in Rio de Janeiro with the specific purpose of presenting the MALDI–TOF MS technique as an efficient methodology to identify Enterobacteriaceae from bovine environments. The MALDI–TOF MS technique results matched the biochemical test results in 92.9% (170/183) of the enterobacteria species and the gyrB sequencing confirmed 100% of the proteomic technique results. The amino acid decarboxylation test made the most misidentifications and Enterobacter spp. was the most misidentified genus (76.9%, 10/13). These results aim to clarify the current biochemical errors in enterobacteria identification, considering isolates from a bovine environment, and show the importance for more careful readings of phenotypic tests which are often used in veterinary microbiology laboratories.

Mussels have a filter system enabling them to take up nutrients from the water, so a microbiological analysis of these bivalve mollusks can show the contamination levels of their surrounding aquatic environment. The present work aimed to isolate Vibrio species from two hundred samples of mussels (Perna perna) incrusted on rocks of the Santana Archipelago and from longline mariculture in Ilha Grande Bay in Angra dos Reis and from Arraial do Cabo, all of which are in Rio de Janeiro state, Brazil. A total of 209 Vibrio were isolated. The most prevalent species was Vibrio parahaemolyticus (44.66%) followed by Vibrio alginolyticus (19.62%) and Vibrio vulnificus (12.44%). All 209 Vibrio isolates tested positive for the RNA polymerase alpha gene (rpoA). The tlh gene (thermolabile hemolysin), a genetic marker for V. parahaemolyticus, and vvhA (cytolysin hemolysin) of V. vulnificus were detected in 85 and 26 isolates, respectively. The MALDI-TOF MS proteomic technique was used to confirm the identification of the 41 V. alginolyticus isolates. Our most important finding was the detection of the tdh virulence gene in 68.20% (58/85) of V. parahaemolyticus environmental strains. Besides the circulation of the virulence gene, the spread of antimicrobial resistance was evaluated and 91.3% (191/209) of the isolates showed resistance to ampicillin, 23.9% (50/209) to ciprofloxacin, 18.6% (39/209) to nitrofurantoin, 5.7% (12/209) to tetracycline, 4.3% (9/209) to pefloxacin and 3.3% (7/209) to chloramphenicol. These findings indicate that environmental isolates can act as reservoirs of virulence and antibiotic resistance genes.

Vibrio species are ubiquitous in aquatic environments, including coastal and marine habitats. Vibrio alginolyticus is an opportunistic pathogen for fish, crustaceans and mussels and their identification by biochemical tests may be impaired due their nutritional requirements. The study used Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) to identify 49 Vibrio spp. isolates associated with mussels (Perna perna) from different locations along the Rio de Janeiro coast. The rpoA gene was used as a genus-specific marker of Vibrio spp. and was positive in all 209 isolates. MALDI-TOF MS confirmed 87.8% of V. alginolyticus when compared to the results of the biochemical tests. Four isolates were identified as Shewanella putrefaciens (8.16%) and one was identified as V. parahaemolyticus (2.0%). Just one isolate was not identified by this technique (2.0%). The pyrH sequencing confirmed 75% of the proteomic technique results. MALDI-TOF MS is an excellent option for characterization of bacterial species, as it is efficient, fast and easy to apply. In addition, our study confirms its high specificity and sensitivity in these marine bacteria identification.