Contaminations of laboratory surfaces with Staphylococcus aureus are affected by the carrier status of laboratory staff

Abstract

Aim: As a biosafety laboratory, we take samples from surfaces in microbiological laboratories to survey the handling of micro-organisms. Whereas contaminations with other micro-organisms were rare, Staphylococcus aureus was found in the working environment of many laboratories. As 20-60% of the healthy population are carriers of S. aureus we wanted to asses the effect of carriers on our sampling results. Methods and Results: Nasal swabs of staff members in nonmicrobiological laboratories and offices as well as surface samples from their personal work environment were taken and analysed for S. aureus DNA. In addition S. aureus strains were isolated using S. aureus-specific agar plates and analysed by randomly amplified polymorphic DNA (RAPD)-PCR and multilocus sequence typing (MLST). Our data show that contaminations with S. aureus in nonmicrobiological environments are common with 29% of the surface samples containing S. aureus DNA. In the working environment of carriers, the number of contaminations was significantly increased compared to the environment of noncarriers. Conclusion: The carrier status of staff members significantly affects the number of contaminations on laboratory surfaces. Therefore, even in the absence of intentional handling of S. aureus, contaminations can be detected on a substantial amount of surfaces. Significance and Impact of the Study: Sampling procedures need to be adapted based on these results with respect to the locations where samples are taken and the threshold for significant contaminations. Because of its wide distribution, S. aureus can serve as a marker for hygienic standards in laboratories.

Detection of adeno- and lentiviral (HIV1) contaminations on laboratory surfaces as a tool for the surveillance of biosafety standards

“…For this purpose, we have been taking swab samples from a specific range of laboratory surfaces and analysed them for the presence of contaminations by organism most frequently handled in Swiss laboratories. This has recently been reported for bacterial pathogens handled in diagnostic facilities (Schmidlin et al. 2010).…”

“…At both locations but particularly at control panels, there is no intentional handling of virus DNA carried out. Because lentiviruses do not belong to the natural flora of the human skin, these contaminations cannot be caused by natural deposition by the laboratory staff as we have recently shown for Staphylococcus aureus (Schmidlin et al. 2010).…”

“…Biosafety standards are defined by the quality and effectiveness of infrastructural, technical and organizational safety measures taken by the facility leading to or preventing surface contaminations. In our laboratory, we have been complementing the inspections by analytical means of swab taking from laboratory surfaces, as previously reported for bacterial pathogens (Schmidlin et al. 2010).…”

“…For this purpose, we have been taking swab samples from a specific range of laboratory surfaces and analysed them for the presence of contaminations by organism most frequently handled in Swiss laboratories. This has recently been reported for bacterial pathogens handled in diagnostic facilities (Schmidlin et al 2010). In this work, we present the development of specific methods for the detection of Ad5 and HIV1-derived lentiviral contaminations in swab samples taken from laboratory surfaces and instrumentations.…”

A combined multi-virulence-locus sequence typing and Staphylococcal Cassette Chromosome mec typing scheme possesses enhanced discriminatory power for genotyping MRSA

“…Approximately 20-60% of the human populations are asymptomatic carriers of S. aureus (Schmidlin et al, 2010). This is a cause for concern as S. aureus can rapidly acquire antibiotic resistance, creating major problems for treatment of infections.…”