Susceptibility of community associated methicillin resistant Staphylococcus aureus isolated from faeces to...

The study aimed to investigate the resistance of methicillin resistant Staphylococcus aureus (MRSA), an indicator used in hospitals but isolated from faecal samples of children in the community, to commonly used antibiotics and antiseptic agents.

S. aureus isolates were identified by phenotypic and genotypic techniques such as biochemical tests and polymerase chain reaction. Antibiotic susceptibility was investigated using the disc diffusion technique while the agar dilution method was used to determine the minimum inhibitory concentration (MIC) of antiseptics.

MRSA showed considerably higher resistance to other antibiotics than methicillin sensitive Staphylococcus aureus (MSSA). Twelve percent of the MSSA were susceptible to all the antibiotics studied while none of the MRSA had this property. A significant difference in susceptibility between MRSA and MSSA to the three antiseptic agents was observed as 68.8%, 75.0% and 100% of MRSA were less susceptible to benzalkonium chloride, chlorhexidine and cetrimide respectively, while 32.0%, 28.0% and 56.0% of MSSA respectively were less susceptible to these agents compared with S. aureus NCTC 6571. Overall, the MICs for the antiseptics were 2-3 times greater in the MRSA than in the MSSA (p < 0.001).

Results show that the concentration of antiseptics used in the prevention of the transmission of infectious agents may have to be raised to cope with the possible presence of MRSA in patients coming into hospital.