PREVALENCE AND ANTIBIOTIC SUSCEPTIBILITY PATTERN OF STAPHYLOCOCUS AUREUS STRAINS FROM CLINICAL SAMPLES IN MINNA, NIGERIA

Introduction: Staphylococci form the commonest agent of hospital infections and pose a major problem because of their growing resistance to the commonly used treatments. Aim: The aim of this study is to survey for the prevalence of antibiotic susceptibility pattern of Staphylococcus aureus strains from clinical samples to common antibiotics in Minna, Nigeria. Method: All samples from wound swab, stool, blood, urine, urethra, endocervical swab, eye, ear, breast abscess etc submitted to General hospital Minna were cultured on sterile blood agar and mannitol salt agar and incubated at 37oC for 24hrs using standard microbiological techniques. Results: Of the 323 different specimens, (79.26%) S.aureus isolates were reported. The highest carrier rate of S. aureus (90.91%) occurred in wound while the least (72.01%) was reported in others. The isolates were highly susceptible to fusidic acid (26.41%) oxacilin (24.32%) vancomycin (20.75%) and trimethoprim (18.86%). Conclusion: fusidic acid with relatively higher susceptibility to clinical isolates of S.aureus can be used for management of these clinical conditions in our locality. The need for appropriate health education to reduce self medication and drug abuse is very imperative and desirous


Introduction
Staphylococci form the commonest agent of hospital infections and pose a major problem because of their growing resistance to the commonly used treatments. The hospital environment may have about 30-40% carrier rate. Staphylococcal infections are characterised by intense suppurative inflammation of local tissues with a tendency for the infected area to become encapsulated leading to abscess formation. The most common staphylococcal infection is the furuncle or boil. Approximately 2-3% of the population have chronic furunculosis. 1 Staphylococcus aureus has associated with different clinical conditions. For instance, it is still one of the most frequently encountered single bacterial species in IJBAR (2010) 01 (05) www.ijbar.ssjournals.com hospitals and continues to be frequent cause of burns and wounds sepsis. It produces pustules, carbuncles and impetigo. It frequently causes septicaemia osteomyelitis, bacteraemia and otitis. 3 S. aureus exhibits remarkable versatility in their behaviour towards antibiotics. 4 Therefore, the insight into the antibiotic profile in any community is very imperative and desirable for effective management of clinical conditions considering the relative differences in the pattern of susceptibility and resistance of S.aureus to antibiotics from one locality to another. S.aureus had been isolated from several clinical specimens from different part of Nigeria. 5,6,7,8,9,10 This study is therefore designed to investigate the antibiotics susceptible to S. aureus strains from clinical sources in Minna, Niger State of Nigeria. Ethical permission was obtained from the hospital.

Antibiotic Susceptibility Testing
The antibiotic susceptibility tests were carried out using the Mueller Hinton agar. All the antibiotics used were from oxoid.

Statistical Analysis
The data obtained in this study were subjected to statistical analysis using graph pad prism, North Crystal 4-12* (Graph pad soft ware version 5.00(Trial), March 12,2007) and Microsoft Excel package.  Table 2. Fusidic acid has the highest susceptibility of (26.41%) followed by oxacillin (24.32%) and vancomycin (20.75%) trimethoprim has the least (18.86%). The difference in pattern of susceptibilities of the S. aureus from clinical sources to various antibiotics was statistically not significant (P<0.05).

Discussion
The overall prevalent rate of 78.26% observed among the clinical isolate is comparatively higher than the report of Onanuga et al 12 (05) www.ijbar.ssjournals.com 45% and 50% respectively in the nostrils of their studied subjects. The highest prevalence of 90.91% in wound swab reported in our present investigation can be attributed to the level of contamination arising from the habit of some of the patients to treat their wound aseptically before seeking appropriate medical attention. Also possible contamination in the areas where low personal hygiene and poor health education still persists and the sexual abuse among youth can be a major factor advanced for the level in urine and high vaginal swab. We found that S.aureus was more susceptible in our locality to fusidic acid followed by oxacillin, vancomycin and the least was trimetoprim Table 2, . The susceptibility of fusidic acid to S.aureus had been documented. 13 Fusidic acid has been known to have a good invitro antibacterial activity against Staphylococcus species by inhibiting protein synthesis. This high activity against the isolates could be linked to the fact that fusidic acid is costly in the locality and is not routinely abuse like the other cheaper antibiotics. Fusidic acid was also very active, this could be linked to the mode of administration which is intravenous formulation and therefore not attracttive and making abuse difficult The resistant of clinical isolates to oxacillin and vancomycin is of great concern. Staphylococcal species resistant to oxacillin has been refferd to as methicillin resistant -Staphylococcus aureus ( MRSA ). This investigation accords Obiazi et al. 10 ; Ehinmidu 6 . They documented resistance of clinical isolates of S.aureus to penicillin, ampicillin and cloxacillin.
The observation in trimethoprim resistance can be attributed in part to earlier exposure to this drug which may have enhanced resistant development 14 . This assertion can further be strengthened by the high level of antibiotic abuse in our locality, arising from self medication which are often associated with inadequate dosage and failure to comply to treatment 15 and availability of antibiotics to consumers across the counter with or without prescription. 16,17 This level of susceptibility to antibiotic in our locality is relatively low and therefore worrisome. This trend had been documented by Eke and Rotimi 18 ; Kesah et al., 19 ; Egah et al 20 and Obiazi et al. 10 in different parts of Nigeria.
In conclusion, fusidic acid with relatively higher susceptibility to clinical isolates of S.aureus can be used for management of these clinical conditions in our locality. The need for appropriate health education to reduce self medication and drug abuse is very imperative and desirous.