Microbiological Analysis of Perianal Abscess and Its Treatment

Abstract

Purpose. To identify the species of infectious organisms present in perianal abscesses and to determine their sensitivity to various antibiotics in order to establish the most effective type of oral antibiotics for treatment. Patients and Methods. Sixteen patients with perianal abscess without skin rupture or identified fistula tract were included in this study. After disinfecting the skin with povidone-iodine and alcohol, exudate was aspirated from the abscess by using a 5-cc needle syringe and sent for common aerobic and anaerobic culture and antibiotic sensitivity tests. Results. The culture rates of aerobic and anaerobic bacteria were 100% and 87.5%, respectively. The species of aerobic bacteria identified included Escherichia coli (13/16), Streptococcus spp. (4/16), Klebsiella pneumoniae (4/16), Citrobacter freundii (2/16), Salmonella enterica serogroup D (1/16), and Staphylococcus aureus (1/16). The species of anaerobic bacteria included Bacteroides fragilis (10 of 14 patients), Bacteroides vulgatus (1/14), Bacteroides stercoris (1/14), Bacteroides thetaiotaomicron (1/14), and Clostridium perfringens (1/14). The most common cultured anaerobic and aerobic bacteria were B. fragilis and E.coli, respectively. Antibiotic sensitivity rates for E.coli were determined to be 84.6%, 84.6%, 69.2%, and 30.8% to amoxicillin-clavulamic acid, cefazolin, ciprofloxacin, and piperacillin, respectively. The resistant rate of E. coli to gentamycin was 30.8%, but the resistant rate to amikacin was 0%. For anaerobic bacteria, antibiotic sensitivity rates were determined to be 100%, 78.6%, 71.4% and 57.1% to the chemicals metronidazole, ampicillin-sulbactam, piperacillin, and clindamycin, respectively. The rates of fistula development at the 12-month follow-up were 28.6% and 0% in patients who had mixed flora and pure aerobic infection, respectively. Conclusion. Our findings show that the first choice of oral antibiotics for the treatment of perianal abscess should be metronidazole combined with augamentin or cefazolin. If aminoglycosides are considered necessary in cases of severe infection, it is recommended that amikacin be administered as our results show a high rate of resistance to gentamycin.