Prevalência e tipagem molecular de Staphylococcus aureus isolados de uma Unidade de Terapia Intensiva de um hospital escola do município de Goiânia, Goiás
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2016-09-30
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Universidade Federal de Goiás
Resumo
Staphylococcus aureus is an important pathogen related to nosocomial infections, with
high prevalence, morbidity and mortality rates. In this context, the Intensive Care Units
(ICU) has been high-risk areas for the selection of multiresistant strains. The environment
(objects, equipment and surfaces) of an ICU can also get contaminated, and microorganisms may remain viable for a long period of time, and can colonize patients,
employees, visitors and other environments. The objectives of the study were to
determine the prevalence of S. aureus contamination in patients and ICU environment of
a university hospital in the city of Goiânia-GO, as well as to determine the antimicrobial
susceptibility and virulence profile of the isolates and perform molecular typing of
methicillin-resistant S. aureus (MRSA) isolates. The isolation and presumptive
identification of S. aureus by phenotypic techniques and the confirmation of the species
by detection of femA gene by PCR were performed. The isolates were subjected to diskdiffusion test for determining antimicrobial susceptibility profile, and those showing
resistance to cefoxitin were subjected to E-Test® to determine the minimum inhibitory
concentration (MIC) to oxacillin and vancomycin, as well as the mecA gene detection for
identification of MRSA strains. In these isolates the SCCmec typing was performed. In all
S. aureus isolates were detected virulence factors-coding genes and held the genetic
comparison for determining the similarity profile by pulsed field gel electrophoresis. Fifty
hundred and thirty six swabs were collected being 134 of patients and 402 of ICU
environment. The prevalence of colonization by S. aureus was 12.7% (68/536), being
13.4% (18/134) for patients and 12.4% (50/402) for the environment. The highest
resistance rate presented was to penicillin (85.3%) followed by erythromycin (69.1%)
clindamycin (66.2%) and sulfamethoxazole-trimethoprim (54.4%). Fifty-six isolates
(82.4%) were classified as multiresistant. The prevalence of MRSA was 20.6% (14/68),
and seven isolates (10.3%) presented intermediate susceptibility to vancomycin (VISA).
The inducible resistance phenotype (iMLSb) was found in 11 strains (16.2%) and the
constitutive resistance (cMLSb) in 25 (36.8%). Eleven isolates showed genes encoding
for at least one virulence factor and were detected six virulence profiles. Of the 14 MRSA
strains, six (42.9%) were SCCmec type IV, five (35.7%) SCCmec type I, two (14.3%)
SCCmec type II and one (7.1%) SCCmec type III. PFGE analysis showed genetic
diversity among the isolates, although a cluster grouped 16 isolates showing the spread
of the bacteria among patients and environment. One MRSA isolate showed genetic
relationship to the USA300 strain and two isolates MRSA/VISA were similar and another
identical to the clone USA400. The results suggest that the prevalence of S. aureus and
MRSA remains high in health institutions, especially in the ICU, with high rates of
antimicrobial resistance and pathogenic potential. The detection of these microorganisms
in the environment shows risk of cross-transmission primarily via health professionals.
Identification of isolates with genetic background of strains acquired in the community
alert to a flow of intra and inter- hospital and community environment. In addition, it is
believed that environmental surfaces can be acting as reservoirs of genes of resistance
and virulence as well as potential sources of contamination to patients, professionals and
environments.
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Veloso, J. O. Prevalência e tipagem molecular de Staphylococcus aureus isolados de uma Unidade de Terapia Intensiva de um hospital escola do município de Goiânia, Goiás. 2016. 103 f. Dissertação (Mestrado em Biologia da Relação Parasito-Hospedeiro) - Universidade Federal de Goiás, Goiânia, 2016.