72 Potential for airborne bacterial contamination in an outpatient respiratory clinic

Abstract

Objective Recent studies have shown that bacteria of clinical significance in respiratory infection, such as Pseudomonas aeruginosa , have potential for airborne dissemination. This study examined airborne bacteria at an outpatient respiratory clinic and to determine levels of antibiotic resistance among airborne isolates. Methods Air was sampled (Casella slit air sampler, 30litres/min) on two separate days at various locations and time points in a Belfast Respiratory Outpatient Clinic, starting before clinic, until clinic finished. Bronchiectasis (BE) patients attended morning clinic, and Cystic Fibrosis (CF) patients in the afternoon. Air samples were deposited onto Muller-Hinton agar, incubated for 24–48 hrs/37°C/O 2 , and individual colonies counted, Gram stained and identified by 16s rRNA sequencing. The antibiotic susceptibility of selected isolates (n = 11) was determined by E-test®. Results The majority of bacteria detected were Gram +ve (184/242; 76%). The most common were Micrococcus, Kocuria and Staphylococcus spp. Moraxella spp. and one Stenotrophomonas maltophilia isolate were also cultured. No apparent differences in bacterial load were observed between either the BE or CF clinics, or at sequential time points. Of the isolates tested, 8/11 (73%) were resistant to clindamycin. Discussion Although Moraxella, staphylococci and S. maltophilia were observed, the majority of bacteria isolated were those normally designated as skin commensals. Work is currently ongoing, using molecular methods to more fully describe the airborne microbiome and resistome, and to compare patient vs airborne isolates to gauge the potential for transmission within the clinic.