Drug Resistance, Serological Study and Plasmid Profile Analysis of Bacterial Isolates from Anorectal Sepsis

Anorectal sepsis is a clinical state accompanied by the infection of the anorectal region of the human body and inappropriately treated sepsis may result in increased morbidity and mortality. Common anorectal sepsis cases found in this study were the anorectal abscess, anal fistula, surgical wound infection and fissure in ano. A total of 100 bacterial positive anorectal sepsis cases collected from patients of three large referral hospitals in Dhaka, Bangladesh were studied during the period from May 2006 to December 2007. Of these anorectal specimens, abscess cases were 42%, wound infection 28%, fistulae in ano were 26% and fissure in ano 4%. The microorganisms obtained from the specimens were identified by phenotypical and biochemical tests. Escherichia coli was the most prevalent isolate (61%) followed by Staphylococcus aureus (22%), Proteus spp. (10%) and Pseudomonas spp. (7%). All the E. coli strains isolated were totally resistant to multiple drugs including ampicillin, cotrimoxazole and nalidixic acid. However, 81%, 58% and 36% of the E. coli isolates were sensitive to gentamycin, ceftazidime and ceftriaxone respectively. S. aureus obtained from all types of anorectal sepsis were sensitive to gentamycin (79%), ceftazidime (46%), ceftriaxone (28%), ciprofloxacin (39%), erythromycin (40%), penicillin (19%), tetracycline (14%) and cephalexin (25%). S. aureus showed 100% resistance to cloxacillin. All the Proteus isolates were totally resistant to penicillin, amoxicillin and cotrimoxazole. However, 55%, 44%, 38% and 25% of these Proteus isolates were sensitive to ceftazidime, gentamicin, ceftriaxone and ciprofloxacin respectively. The isolated Pseudomonas spp. showed 67%, 63%, 45% and 25% sensitivity to gentamycin, ceftriaxone, ceftazidime, ciprofloxacin respectively and absolute resistance to penicillin, amoxycillin, cotrimoxazole, cephalexin, cephradine, ampicillin, nalidixic acid and nitrofurantoin. In this study, the most prevalent serotype of E. coli was found to be O25 and O20 and the other isolates of E .coli were untypable. In plasmid profile analysis of 14 randomly selected E. coli isolates, 10 different plasmid patterns ranging from 1 to 140 MDa were observed. However, no correlation could be ascertained between plasmid pattern and drug resistance.