This study evaluated biofilm formation and antibiotic susceptibility in 36 clinical S. aureus isolates recovered from orthopaedic patients and detected the presence of intercellular adhesion and adhesin genes. Staphylococcus aureus was isolated from nasal swab, wound and urine specimens collected from orthopaedic patients in National Orthopaedic Hospital Dala, Kano over a period of three months. The isolates were identified using rapid identification kit for Staphylococcus species. The antibiotics susceptibility of the isolates was determined using modified disc diffusion method. Phenotypically, the biofilm formation was assessed using the Congo red agar method and microtitre plate assay. Polymerase chain reaction (PCR) analysis was used to detect biofilm-associated genes and characterize the isolates. The isolation rate of S. aureus from the samples (n = 134) was 26.8%, mainly from nasal swab (36%) and wound swab (36%). A total of 19 (52.7%) of the isolates showed positive for slime production. Majority of the isolates 29/36 (81.6%) were biofilm positive with only 2 (5.5%) and 5 (13.8%) as strong biofilm-formers and moderate biofilm-formers respectively. Molecular evaluation of the biofilm-associated genes in 12 S. aureus isolates revealed the prevalence of bbp genes (25%), clfA genes (16.6%) and the icaA (8.3%). None of the isolates harboured the fnbA and cna genes. There is no significant difference (P > 0.05) in the antibiotic resistance pattern between biofilm-positive and biofilm-negative S. aureus isolates. This result revealed that phenotypically most of the S. aureus isolates were biofilm formers but few of them chromosomally harbour the biofilm-associated genes.

Biofilm formation and resistance to methicillin are among the factors that makes Staphylococcus aureus a very important human pathogen in both health-care and community settings. This study investigated methicillin-resistance among biofilm-producing S. aureus isolated from 49 orthopaedic in-patients within a 3 months period. Wound swabs, nasal swabs, bed swabs and urine samples were collected from each patient. The samples were cultured and screened for presence of S. aureus while the micro-titre plate method was used to detect biofilm producing isolates. PCR technique was finally used to detect the presence of mecA gene in methicilin resistant S. aureus (MRSA) isolates. Findings reveal 14.8% of bacterial isolates were Staphylococcus aureus of which 96.4% were biofilm-producers. However, strong biofilm producers constitute 11.1%. The mecA gene was detected in 15.8% of the MRSA isolates. Therefore, MRSA among biofilm-producing S. aureus is a potential threat primarily to the community of National Orthopaedic Hospital Dala and a major public health challenge. Keywords: Biofilm, Methicillin-resistance Staphylococcus aureus (MRSA), mecA gene, Orthopaedic patient

Escherichia coli has carved its niche in the urinary tract with the formation of a formidable matrix called biofilm. This biofilm is not only recalcitrant to the body's immune system but also resistant to antibacterial agents. Senna siamea (Lam) Irwin and Barneby is a medicinal plant with established antibacterial effect against planktonic cells of many bacteria. An attempt was made herein to evaluate the effect of its leaf extract and fractions on biofilm of E. coli isolates. Crude extracts of leaf, stem bark and root of this plant were prepared using ethanol as the solvent for the cold extraction. Phytochemical screening was carried out on the three extracts. Two E. coli strains from different antenatal patients attending General Hospital, Kafanchan, Kaduna were donated to us by a researcher from Ahmadu Bello University, Zaria and the reference strain, E. coli, WDCM 00013 (from Germany) were tested for biofilm production using the Congo red method. Antimicrobial susceptibility testing of the crude extracts against the isolates was carried out using the agar diffusion method. The Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) were determined for the leaf extract of the plant using micro broth dilution and agar diffusion methods respectively. In order to establish the antibiofilm activities of the leaf extract of the plant, sub-inhibitory concentrations (sub-MIC) were used against the test isolates in the remaining assays in the work. Column chromatography backed by thin layer chromatography (TLC) was used to fractionate leaf extract (having the best antibacterial activity) of the plant, using different ratios of a combination of hexane, ethyl acetate and nbutanol as fractionating solvents. MIC and MBC of the leaf extract were and 50 mg/ml respectively. High values of percentage biofilm inhibition were observed against all the bacterial isolates from the antibiofilm assay. Combination of solvents in the increasing order of polarity enhanced the antibiofilm activity of the various fractions of the leaf extract of Senna siamea. In conclusion, further fractionation of Senna siamea leaf extract increases its antibiofilm activities.