Surveillance of Surgical Site Infections in Post-operative Patients and Bacterial Susceptibility in Tanzania

Abstract

Surgical site infections (SSI) are infections occurring within 30 days of the postoperative procedure. They are common post-operative morbid complications that may cause death if not treated timely. The common causes of SSI include infectious bacteria, such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and some Enterobacteriaceae. This was a cross-sectional study conducted at St. Francis Referral Hospital, Ifakara, Tanzania over a period of 12 months to investigate the causes of SSI and antimicrobial susceptibility of the causal agents. The study included consenting patients who developed post-operative wound infections during the study period. Identification of infecting micro-organisms and their antimicrobial susceptibility was done at St Francis Referral Hospital Laboratory. Antibiotic susceptibility tests of the isolates were performed by the Kirby–Bauer (K–B 1966) disc diffusion test, and extended spectrum β-lactamase producing Gram-negative species were tested by using the modified double disc synergy test. A total of 130 patients developed post-operative wound infection. Third and fourth decades were the most affected age groups; females were the dominant group with a 1:1.4 male: female ratio. Out of the 130 specimens, 121 isolates were obtained, and nine specimens were negative for culture. P. aeruginosa was the most commonly isolated agent (42.1%), followed by S. aureus (19.8%), while the least were Streptococcus spp. at 0.8%. The isolates showed the highest resistance to ampicillin (91.7%), and least to ciprofloxacin (1.7%). P. aeruginosa was highly resistant to both amoxicillin + clavulanic acid (98%), and to ampicillin (98.0%). Extended spectrum β-lactamase E. coli producers were 68.4%. The bacteria causing SSI require continuous monitoring to obtain data that will support local and national guidelines in the battle against antimicrobial resistance, and improve therapeutic outcomes following surgical interventions.