Optimization of PMA ‐qPCR for Staphylococcus aureus and determination of viable bacteria in indoor air

This study evaluated quantitative PCR (qPCR) with propidium monoazide (PMA) to quantify S. aureus. The results showed comparable S. aureus counts between exclusively live cells and mixtures of live/dead cells by qPCR with 1.5 or 2.3 μg/mL PMA (P>0.05), illustrating the ability of PMA‐qPCR to detect DNA exclusively from viable cells. Moreover, qPCR with 1.5 or 2.3 μg/mL PMA performed optimally with linearity over 103‐108 CFU/mL (R2≥0.9), whereas qPCR with 10, 23 or 46 μg/mL PMA significantly underestimated viable counts. S. aureus and total viable bacteria were further determined with PMA‐qPCR (1.5 μg/mL) from 48 samples from a public library and two university dormitories and four from outside. Viable bacteria averaged 1.9×104 cells/m3, and S. aureus were detected in 22 (42%) samples with a mean of 4.4×103 cells/m3. The number of S. aureus and viable bacteria were positively correlated (r = 0.61, P<0.005), and percentages of S. aureus relative to viable bacteria averaged 12‐44%. The results of field samples suggest that PMA‐qPCR can be used to quantify viable S. aureus cells. This article is protected by copyright. All rights reserved.
Source: Indoor Air - Category: Occupational Health Authors: Tags: Original Article Source Type: research