Publication:

Relationship between resistance to antibiotics and insusceptibility to biocides of Staphylococcus aureus and Pseudomonas aeruginosa isolated in Indonesian hospitals

Background Several studies have shown that bacteria acquiring resistance to biocides may acquire resistance to antibiotics simultaneously. This study aimed to evaluate the relationship between resistance to antibiotics and insusceptibility to biocides of S. aureus and P. aeruginosa isolated in Indonesian hospitals.

Methods 61 isolates of S. aureus from nurses’ nasal cavities and 46 isolates of P. aeruginosa from hospital environments were divided into those with higher minimum inhibitory concentration (MIC) (Higher MIC group) and those with lower MIC (lower MIC group) depending on growth in MIC of chlorhexidine gluconate (CHG) and benzalkonium chloride (BZK) of each standard strain. Afterwards, susceptibility to antibiotics of the 2 groups was compared.

Results Increases in MICs of CHG were found in both species. Some of P. aeruginosa also had higher MICs of BZK. Relationship between antibiotic resistance and insusceptibility to biocides differed among species, biocides and antibiotics. In S. aureus, isolates in the Higher MIC group tended to be more resistant to ampicillin (0.167). In P. aeruginosa, resistance to aminoglycosides was observed more frequently in the Higher MIC group for CHG and it was significant in amikacin (p = 0.002). Further analysis is necessary to determine the mechanisms of the relationship between aminoglycoside resistance and CHG insusceptibility in P. aeruginosa.

Conclusions Increase in insusceptibility to biocides was found in isolated S. aureus and P. aeruginosa and a relationship between insusceptibility to CHG and resistance to aminoglycosides was observed in P. aeruginosa.