Higher prevalence of coagulase-negative staphylococci carriage among reclaimed water spray irrigators

Coagulase negative staphylococci (CoNS) are leading causes of nosocomial infections and community-acquired methicillin-resistant CoNS (MRCoNS) infections are increasing. CoNS have been previously detected in reclaimed water. To date, no studies have evaluated the prevalence of CoNS carriage among humans exposed to reclaimed water in the U.S. We examined the prevalence and odds of CoNS and antibiotic-resistant CoNS carriage in spray irrigators exposed to reclaimed water compared to controls. We collected nasal and dermal swab samples from 19 reclaimed water spray irrigation workers (n=96 total samples) and 24 controls (n=92 total samples). Samples were analyzed for CoNS using culture-based assays. Isolates were confirmed using biochemical tests and PCR. Antimicrobial susceptibility testing was performed using disk diffusion. Data were analyzed by two-sample proportion tests, logistic regression, and generalized linear mixed effects models. The prevalence of CoNS, antibiotic-resistant CoNS, and MRCoNS carriage among spray irrigation workers was 79% (15/19), 32% (6/19), and 16% (3/19), compared to 13% (3/24), 4% (1/24), and 0% (0/24) of controls. Spray irrigators were more likely to be carriers of CoNS (p<0.01), antibiotic-resistant CoNS (p<0.01), and MRCoNS (p=0.02) compared to controls. The odds of CoNS carriage significantly increased with exposure to reclaimed water (p=0.04) even accounting for changes over time (p=0.05). Our data highlight the need to further examine the potential dissemination of CoNS and antibiotic-resistant CoNS from reclaimed water into the environment and human communities and related public health implications.