Methicillin resistant Staphylococcus aureus (MRSA) as a major cause of infections in hospital and community settings is a global health concern. The purpose of this study was to determine the antimicrobial susceptibility and the molecular characteristics of MRSA strains causing community-acquired (CA) and hospital-acquired (HA) infections in Tunisia.
A total of 135 non-duplicate MRSA strains were consecutively collected from five Tunisian hospitals. Antimicrobial susceptibility was done by disc diffusion method and by MIC. The presence of pvl (Panton Valentine Leukocidin) and tst-1 (toxic shock syndrome toxin 1) Genes were determined by PCR method. Strains were typed by agr, SCCmec typing, PFGE and spa typing.
Forty-nine strains (36.3%) were CA. HA strains showed significantly higher rates of resistance than the CA strains. One HA strain was resistant to teicoplanin (MIC = 4 µgml-1). The pvl gene was detected in 83.7% and 32.6% of CA and HA strains, respectively. Only eight strains were tst-1 positive. PFGE revealed 61 pulsotypes among HA strains and 20 pulsotypes among CA strains. Twenty-four spa types were identified. spa type t044 was the most common, representing 69.4% and 25.6% among CA and HA strains respectively. Most of t044 strains was pvl-positive, harbored agr3 and SCCmec IV and were resistant to kanamycin, tetracycline and fusidic acid. t037, agr1 and SCCmec III was the most prevalent among HA-MRSA.
Genetically diverse MRSA strains were circulating in our hospitals with relatively high prevalence of spa type t044 and t037. Regular surveillance studies on MRSA are needed to monitor the evolution of antimicrobial susceptibility, to better elucidate the distribution of existing MRSA clones and to detect the emergence of new MRSA clones.