Avaliação do potencial de formigas (Hymenoptera: formicidae) como vetores mecânicos de bactérias do gêneroSstaphylococcus no ambiente hospitalar.

摘要

In a hospital environment, these bacteria can be spread by insects such as ants, which arecharacterized by high adaptability to the urban environment. Staphylococcus is a leadingcause of hospital infection. In Europe, Latin America, USA and Canada, the group ofcoagulase negative staphylococci (CoNS) is the second leading cause of these infections,according to SENTRY (antimicrobial surveillance program- EUA). In this study, weinvestigated the potential of ants (Hymenoptera: Formicidae) as vehicle mechanics ofStaphylococcus bacteria in a public hospital, in Natal-RN. The ants were collected, day andnight, from June 2007 to may 2008, in the following sectors: hospitals, laundry, kitchen,blood bank. The ants were identified according to the identification key of Bolton, 1997.For the analysis of staphylococci, the ants were incubated in broth Tryptic Soy Broth (TSB)for 24 hours at 35 º C and then incubated on Mannitol Salt Agar. The typical colonies ofstaphylococci incubated for 24 hours at 35 ° C in Tryptic Soy Agar for the characterizationtests (Gram stain, catalase, susceptibility to bacitracin and free coagulase). Theidentification of CoNS was performed through biochemical tests: susceptibility tonovobiocin, growth under anaerobic conditions, presence of urease, the ornithinedecarboxylation and acid production from the sugars mannose, maltose, trehalose, mannitoland xylose. The antimicrobial susceptibility examined by disk-diffusion technique. Thetechnique of Polymerase Chain Reaction was used to confirm the presence of mecA geneand the ability to produce biofilm was verified by testing in vitro using polystyrene inertsurface, in samples of resistant staphylococci. Among 440 ants, 85 (19.1%) were carryingcoagulase-negative staphylococci (CoNS) of the species Staphylococcus saprophyticus(17), Staphylococcus epidermidis (15), Staphylococcus xylosus (13), Staphylococcushominis hominis (10), Staphylococcus lugdunensis (10), Staphylococcus warneri (6),Staphylococcus cohnii urealyticum (5), Staphylococcus haemolyticus (3), Staphylococcussimulans (3), Staphylococcus cohnii cohnii (2), and Staphylococcus capitis (1). NoStaphylococcus aureus was found. Among the isolates, 30.58% showed resistance toerythromycin. Two samples of CoNS (2.35%), obtained from the ant Tapinomamelanocephalum collected in the post-surgical female ward, S. Hominis hominis and S.lugdunensis harbored the mecA gene and were resistant to multiple antibiotics, and thespecie S. hominis hominis even showed to be a biofilm producer. This study proves thatants act as carriers of multidrug-resistant coagulase-negative Staphylococci and biofilmproducers and points to the risk of the spreading of pathogenic microorganisms by thisinsect in the hospital environment