Vol. 6, Issue 2, Part A (2024)

Background: Chronic Suppurative Otitis Media (CSOM) is a long standing infection of middle ear characterized by ear discharge and permanent perforation. It is a common public health problem worldwide and a major cause of hearing impairment in developing countries like Bangladesh. Due to its recurrent nature and the development of resistant pathogenic organisms, control of infection poses a greatest therapeutic challenge. There are variations in aetiological agents and their antimicrobial susceptibility patterns vary with time and geographical area as well as continent to continent. This study was carried out to know the bacterial etiology of CSOM and their antibiotic susceptibility pattern.

Objectives: To study the bacterial profile and determine the sensitivity spectrum of isolates from Chronic Suppurative Otitis Media (CSOM) patients.

Materials and Methods: This cross sectional study was conducted at Department of Otolaryngology and Head-Neck Surgery, Dhaka Medical College Hospital (DMCH) for six-month period after acceptance of protocol. Individuals attending the otolaryngology in-patient and out-patient department (OPD) of Dhaka Medical College Hospital (DMCH), presenting with ear discharge persisting more than 12 weeks and who had not received antibiotic therapy (topical or systemic) in the last 48 hours, irrespective of age and gender, were recruited in this study. Ethical issues were ensured properly and inclusion was confirmed following signing written informed consent. A total of 52 patients clinically diagnosed of CSOM were enrolled in the study and the samples were obtained from each patient using sterile cotton swabs and sent to Microbiology laboratory of DMCH. Bacterial isolates were identified using standard methods and antibiotic susceptibility testing was done by using Kirby Bauer disc diffusion method as per CLSI guidelines.

Results: Out of 52 cases 37 (71.15%) cases were culture positive and 15(28.85%) cases showed no growth. Among the culture positive specimens, the majority of isolates were Pseudomonas aeruginosa (43.14%), followed by Staphylococcus aureus (18.92%), Escherichia coli (13.51%), Coagulase negative Staphylococcus (8.11%), Proteus (5.41%), Klebsiella (2.70%) and mixed (8.11%). P. aeruginosa showed the greatest sensitivity to Imipenem (93.75%), Colistin (93.75%) and Amikacin (87.50%). However, its sensitivity was shown to be reduced to fluoroquinolones such as Ciprofloxacin (43.75%) and Levofloxacin (31.25%).Staphylococcus aureus showed the highest sensitivity to Amikacin (85.71%) Vancomycin (85.71%), Linezolid (71.43%) while Escherichia coli was sensitive to Amikacin (100%), Imipenem (100%) and Ciprofloxacin(80%) and Coagulase negative Staphylococcus demonstrated sensitivity to Linezolid(100%), Amikacin(100%) and Ciprofloxacin.(100%).

Conclusion: The most common bacteriological agent associated with CSOM in our study area was Pseudomonas aeruginosa followed by Staphylococcus aureus. P. aeruginosa showed the greatest sensitivity to Imipenem, Colistin and Amikacin. However, its sensitivity was shown to be reduced to fluoroquinolones such as Ciprofloxacin and Levofloxacin, which have been widely used for treating Pseudomonas infections. Most S. aureus isolates were found to be sensitive to Vancomycin, Amikacin and Linezolid while Escherichia coli was sensitive to Amikacin, Imipenem and Ciprofloxacin. Coagulase negative Staphylococcus demonstrated sensitivity to Linezolid, Amikacin and Ciprofloxacin. Almost all the isolated bacteria showed a considerable level of resistance to more than one antibiotic that are commonly used in clinical practice, especially penicillin and Tetracycline. Therefore, it is important to perform antimicrobial susceptibility tests on aural swab from CSOM patients. Imipenem and Colistin, though shown to be highly effective drugs by the present study, are considered to be reserve drugs and should be used cautiously. Treatment with Amikacin may be considered.