Epidemiology and antibiotic susceptibility of bacterial isolates from Northern Pakistan

This study was conducted in Khyber Teaching Hospital, to evaluate antimicrobial susceptibility pattern among pathogens isolated in a tertiary care hospital. Specimens were collected in sterile containers and cultured for a period ranging from 24-48 h at 37 degrees C aerobically, using appropriate bacteriological isolation media. Isolates were identified using Gram staining and biochemical reactions. Antibiotic susceptibility was determined by standard disc diffusion (Kirby-Bauer) Method. Among gram-negative rods, Escherichia coli was the predominant pathogen 315 (34.5%), followed by Citrobacter spp. 124 (13.6%), Enterobacter spp. 80 (8.8%), Pseudomonas spp. 51 (5.6%) Proteus spp. 35 (3.8%) Morganella morganii 16 (1.8%) and Salmonella spp. 8 (0.9%). Staphylococcus aureus was the predominant gram positive pathogen 196 (21.4%) followed by Staph epidermidis 32 (3.5%) and Streptococci 7 (0.7%). Pseudomonas spp. and E. coli were the most common pathogens recovered from mixed polymicrobial growth. Out of 16 antimicrobial agents tested, only 6 were effective, inhibiting growth of >50% of the strains of each isolated pathogen. The rest of the 10 antimicrobial agents tested were ineffective to inhibit growth of even 50% of the strains of recovered pathogens. Although the susceptibility pattern to some of the antibiotics such as Imipenem and Meropenem is very good but they are very expensive. The cheaper and affordable antibiotics were least effective. The increasing level of resistance in microorganisms to these cheaper low cost agents is a matter of significant concern.