Characterization of extended spectrun β-lactamase (ESBL) from stanphylococcus aureus recovered from surgical wound patients

Olutola, Olusayo Titilope (2015)




This study isolated and identified Staphylococcus aureus strains from surgical wounds; determined the antibiotic susceptibility pattern of the S. aureus isolates; evaluated the incidence of β-lactamase and extended spectrum β-lactamase (ESBL) production in S. aureus. This was with a view to characterizing the ESBL genes in S. aureus isolates recovered from surgical wound patients. One hundred and ten and 107 samples were collected from wounds and anterior nares respectively of subjects at the Obafemi Awolowo University Teaching Hospital Complex (OAUTHC), Ile-Ife, Nigeria, using sterile cotton-tipped applicators. The primary isolation media were nutrient agar and mannitol salt agar. The isolates were identified as S. aureus based on standard methods. The antibiotic susceptibility typing was conducted using Kirby-Bauer disc diffusion method and interpreted using standard protocol. The acidometric method was used for β-lactamase detection. The induction of β-lactamase was carried out and the enzyme was assayed by the micro-iodometric method. The polymerase chain reaction (PCR) based technique was used for the detection of the resistance genes (MecA, SHV and TEM). Forty seven (42.7%) S. aureus isolates were obtained from 110 wound samples collected while 34 (31.8%) S. aureus isolates were also obtained from 107 samples collected from the anterior nares. Forty seven (100%) of the S. aureus isolated from wound samples were multiple-resistant while 34 (100%) of the S. aureus isolates from anterior nares were also multiple-resistant. β-lactamase production was observed in 14 (41.2%) and 26 (55.3%) of S. aureus isolated from the anterior nares and wounds respectively. The induction of β-lactamase test showed that the enzyme was both constitutive and inductive. MecA gene was detected in 2 (50%) of the methicillin resistant Staphylococcus aureus (MRSA) strains tested and Sulfhydryl variant (SHV) gene was detected in 13 (65%) of the strains tested. BlaTEM gene was not detected in any of the strains. There was no significant difference (p > 0.05) between the resistance patterns of S. aureus isolates from anterior nares and wounds. The study concluded that the prevalence of multiple-resistant bacterial isolates among surgical wound patients was of epidemiological significance in the control of infectious agents.