Introduction and objectives Mycobacterium abscessus pulmonary infection in patients with cystic fibrosis (CF) is associated with significant morbidity, and the prevalence is increasing. The cause of the apparent increase is unknown. Contributing factors may include the ageing CF population, and the potential for patient-to-patient transmission. To date, there is a paucity of data describing the activity of common hospital biocides against this organism.
Methods M. abscessus isolates (n =13) were recovered from CF and non CF respiratory specimens. Seven commonly employed hospital biocides (Steri-7TM, Difficile-STM, HydrexTM, CutanTM, StelliseptTM, Rely+OnTM PeraSafeTM, DistaclorTM) were assayed for their biocidal activity against M. abscessus. Fresh cultures of NTM were exposed to biocide in liquid medium as per manufacturers instruction and were immediately plated following the completion of the contact period. The mean concentration of NTM plated was 9.82 × 106 colony forming units (CFU) (range: 1.63 × 105 – 1.12 × 108). Additionally, the remaining bacteria/biocide solution was enriched non-selectively in Mueller Hinton broth (37oC/1 week). Following this, growth of surviving bacteria was assessed with broth turbidity.
Results After appropriate exposure of NTM to biocide, all NTM isolates survived in Steri-7TM, HydrexTM, StelliseptTM and Rely+OnTM PeraSafeTM. One out of 13 NTM cultures was killed by Difficile-S TM and 1 by DistaclorTM, representing a 5 log kill. Two isolates were killed by CutanTM again representing a 5 log kill. Following enrichment, StelliseptTM showed the greatest biocidal activity with 11/13 isolates, whereas 2/13 cultures were killed by DistaclorTM. All other biocide/culture combinations yielded growth.
Conclusions These data indicate that M. abscessus may persist after exposure to several commonly employed hospital biocides. Given the importance of effective infection prevention and control, further work is urgently needed to define unequivocal biocide contact treatments to ensure successful eradication.
Acknowledgements SC is a CF Trust funded Clinical Fellow