Antibiotic susceptibility profile of methicillin-resistant staphylococci isolated from nasal samples of hospitalized patients

The aim of this study was to evaluate the prevalence rate and antibiotic resistant pattern of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). A prospective study was conducted at Holy Family Hospital Rawalpindi, Pakistan and Microbiology Research Laboratory, Quaid-i-Azam University, Islamabad, Pakistan during the period from December 2007 to August 2008. The antibiotic resistance pattern was studied for MRSA and MRSE isolated from nasal samples from patients admitted in medical and surgical intensive care units. The study was conducted on 283 isolates. The results depicted that 25% isolates of S. aureus were MRSA and 29.78% isolates of S. epidermidis were MRSE. All MRSA and MRSE were susceptible to vancomycin and quinopristin/dalfopristin while all isolates of MRSE were susceptible to teicoplanin. All the isolates of MRSA and MRSE were multidrug-resistant. The susceptibility of the isolates to the drugs varied greatly. The resistance rate of MRSA to various antibiotics was found to be as follow: cephalaxin (90%), cephalothin (58%), cephradine (86%), ciprofloxacin (80%), gentamicin (34%), imipenum (42%), levofloxacin (75%), tetracycline (49%), rifampicin (14%) and teicoplanin (3%). The resistance rate of MRSE to various antibiotics was found to be as follow: cephalaxin (64%), cephalothin (29%), cephradine (64%), ciprofloxacin (50%), gentamicin (21%), imipenum (7%), levofloxacin (21%), tetracycline (21%) and rifampicin (29%). The minimum inhibitory concentration (MIC) value for MRSA and MRSE in case of vancomycin ranged 1-4 mu g/ml, for tetracycline 4-128 mu g/ml, for rifampicin 0.5-32 mu g/ml and for gentamicin 0.5 - 64 mu g/ml. Both MRSA and MRSE showed variable susceptibility with different antibiotic groups but high susceptibility with streptogramin and glycopeptide antibiotics.