Comparison of sugars fermentation in methicillin resistant and sensitive Staphylococcus aureus isolates

The mec A gene in Staphylococcus aureus leads to production of new penicillin-binding protein called PBP2a. This phenomenon may change some phenotypic properties. The aim of this study was the comparison of sugars fermentation in MRSA (Methicillin resistant Staphylococcus aureus) and MSSA (Methicillin sensitive Staphylococcus aureus) isolates. Total 206 MRSA and MSSA isolates (57 MRSA and 149 MSSA isolates) obtained from 120 inpatients and 86 healthy carriers in the Gorgan were tested. Sugar fermentation carried out in phenol red broth medium, containing glucose, galactose, arabinose, fructose, xylose, rhamnose, mannose, sucrose, trehalose, raffinose or maltose. Change in color after 24 hours incubation at 37°C were recorded. The data were analyzed by SPSS software, using Chi squared test and P<0.05 was considered as meaningful. The fermentation of glucose at the 4th hour of incubation happened in 10(17.5%) and 11(7.4%) of MRSA and MSSA isolates respectively (P=0.03). The ability ferment rhamnose and xylose in MRSA isolates were 11 (19.3%) and 6 (10.5%), and in MSSA strains were 3 (2%) and 4 (2.7%) respectively. The differences between MRSA and MSSA isolates was statistically significant (P<0.05). The highest difference between S.aureus which isolated from patients and carriers were seen in fermentation of fructose [120 (100%) vs 80 (93%)], raffinose [46 (38.3%) vs 2 (2.3%)] and rhamnose [14 (11.7%) vs 0 (0%)] (P<0.005). The ability of S.aureus isolates with ability of raffinose fermentation isolated from urinary tract infections was 23 (%56.1), which is significant (P=0.03). Methicillin resistant in Staphylococcus aureus isolates is accompanied with increased ability of sugars fermentation. The ability of sugars fermentation in Staphylococcus aureus isolated from patients is generally more than healthy carriers.