Prevalence of biofilm and betalactamase-producing staphylococcus in nasal and throat isolates from healthy volunteers: a medical alert

ABSTRACT

To study the prevalence of virulence factors such as Biofilm and Beta-lactamase in Staphylococcus isolates residing in nasal and throat mucosa in healthy volunteers. Nasal and throat swabs were taken from 100 healthy volunteers at Gulf Medical University and Gulf Medical College Hospital, Ajman, UAE, and cultured for Staphylococcus isolates on appropriate culture media. The isolate were classified as Staphylococcus aureus or Coagulase Negative Staphylococcus [CoNS] based on the growth characteristics on Mannitol Salt Agar and standard tube coagulase test. They were further tested for Biofilm production by Christensen's tissue culture plate and Congo red agar methods. The positive samples were identified for beta-lactamase by iodometric tube method. Of the 100 Staphylococcus isolates, 41 were Staphylococcus aureus of which 25 [61%] were positive for biofilm production whereas 19 [46.3%] were Beta-lactamase positive. Of the 16 [39%] biofilm negative Staphylococcus aureus isolates, 13 [31.7%] were Beta-lactamase positive. Among the 59 CoNS isolates, 38 [64.4%] were positive for biofilm production and 18[30.5%] were Beta-lactamase positive. Twenty one CoNS samples [35.5%] were negative for both biofilm and Beta-lactamase production. Biofilm production in Staphylococcus aureus and CoNS did not show any significant difference [61% and 64.4%]. Predominance of Staphylococcal isolation was in males between the age group of <20 years, mostly from the nasal site. Biofilm-producing Staphylococcus appear to inhabit the normal flora of the nasal and throat mucosa of healthy individuals. Beta-lactamase production was found to be higher in Staphylococcus aureus positive for biofilm producers as compared to CoNS. Transmission of these biofilm producers with drug resistance factors from the healthy individuals to those at risk, like patients on long term catheterization or with indwelling devices need to be considered