|Year : 2015 | Volume
| Issue : 1 | Page : 25-28
A prospective study on aetiological agents of acute and chronic suppurative otitis media
Sahira Haneefa, Geetha Raveendran, Ramani Bai Joseph Theodore
Department of Microbiology, Government Medical College, Thiruvananthapuram, Kerala, India
|Date of Web Publication||16-Jun-2015|
Department of Microbiology, Government Medical College, Thiruvananthapuram, Kerala
Source of Support: None, Conflict of Interest: None
Otitis media is a persistent, insidious, and dangerous disease because of multiple aetiology and serious complications. Hence, a study was conducted to find out the bacterial and fungal aetiology of suppurative otitis media. Aim: The aim was to find the prevalence of bacterial and fungal pathogens in acute and chronic otitis media. Materials and Methods: A total of 260 patients having otitis media belonging to all age groups and both sexes who attended the ENT outpatient department were selected for study for a period of 1-year. Ear discharge was collected under aseptic precautions using sterile cotton swabs. Both bacterial and fungal culture were done. The antimicrobial susceptibility of bacterial isolates was done including detection of extended-spectrum β-lactamase and detection of metallo β-lactamase for resistant strains. Results: In acute suppurative otitis media, Gram-positive organisms 48 (55.18%) were predominant compared to Gram-negative organisms 37 (42.52%). No fungal isolates were obtained in the present study. In the case of chronic suppurative otitis media (CSOM), bacteria were isolated in 129 (74.57%) cases and fungus in 41 (23.7%) cases. Polymicrobial infection was found only in 14 (10.85%) cases. Among the bacterial isolates in CSOM, Gram-negative organisms (65.35%) were more compared to Gram-positive organisms (35.65%).
Keywords: Extended spectrum β-lactamase, metallo β-lactamase, otitis media
|How to cite this article:|
Haneefa S, Raveendran G, Theodore RJ. A prospective study on aetiological agents of acute and chronic suppurative otitis media. J Acad Clin Microbiol 2015;17:25-8
|How to cite this URL:|
Haneefa S, Raveendran G, Theodore RJ. A prospective study on aetiological agents of acute and chronic suppurative otitis media. J Acad Clin Microbiol [serial online] 2015 [cited 2022 Oct 7];17:25-8. Available from: https://www.jacmjournal.org/text.asp?2015/17/1/25/158792
| Introduction|| |
Otitis media occurs in both children and adults without any age limits. It is a cause of conductive deafness, which may lead to the delayed development of speech and language in children. Early detection of the disease is necessary for better treatment and management. The prompt management of infection based on culture and sensitivity also help in preventing further complications like mastoiditis and brain abscess. 
| Materials and methods|| |
The aim was to find the prevalence of bacterial and fungal pathogens in acute and chronic otitis media.
- To find the prevalence of bacterial and fungal pathogens in acute and chronic otitis media in the ENT outpatient department of Government Medical College, Thiruvananthapuram.
- Identification and characterisation of the pathogens and their antibiogram.
Setting and period of study
The study was done by the Department of Microbiology in collaboration with the Department of ENT, Government Medical College, Thiruvananthapuram. The study was done for a period of 1-year starting from April 2009 to March 2010.
All cases of acute suppurative otitis media (ASOM) and active chronic suppurative otitis media (CSOM).
All cases of otitis media who were on antibiotic therapy at any time during the past 1-week.
Clinical information such as duration of symptoms, predisposing factors, history of recurrent infection, and the treatment taken.
Ear discharge was collected under aseptic precautions using sterile cotton swabs. The swabs were processed immediately in the laboratory. , Microscopic examination (both Gram's staining and KOH wet mount) and culture were done. Specimen was inoculated on blood agar, MacConkey agar, salt agar, and Sabouraud's dextrose agar (SDA) and incubated at 37°C. Another SDA tube inoculated with the specimen was incubated at room temperature.
The identification of the bacterial pathogen was done based on Gram stain, growth on culture, and biochemical properties using standard laboratory procedures. , Antibiotic sensitivity testing was done according to Clinical and Laboratory Standards Institute guideline using disc diffusion method (Himedia disc). Detection of extended-spectrum β-lactamase (ESBL) and metallo β-lactamase (MBL) for resistant Gram-negative strains , were done by the double disc diffusion method.
Fungal growth obtained on SDA was examined for characteristics such as the rate of growth, colony morphology, and pigmentation.  Fungal growth was examined by a lactophenol cotton blue tease mount preparation and slide culture. A negative fungal culture report was given after 4 weeks.
| Results|| |
Of 260 otitis media patients 173 (66.54%) had active CSOM and 87 (33.46%) had ASOM. Incidence of ASOM was highest in children <10 years, that is, 46/87 (52.87%). In ASOM, 48 (55.18%) Gram-positive organisms were isolated, being slightly more than 37 (42.52%) Gram-negative organisms [Table 1]. Staphylococcus aureus was the predominant organism isolated, that is, 44 (50.58%) followed by Pseudomonas aeruginosa, 28 (32.18%). Haemophilus influenzae was isolated from two cases. No fungal isolates were obtained in ASOM in the present study.
The highest incidence of CSOM of 71 (41.04%) was in the age group of 21-30 years, In the case of CSOM, bacteria were isolated in 129 (74.57%) cases and fungus in 41 (23.7%) cases. There was polymicrobial infection in 14 (10.85%) cases and concomitant bacterial and fungal infection in 9 (6.98%) cases. Of 143 isolates, Gram-negative organisms accounted for 92 (53.18%) while 51 (42.52%) were Gram-positive organisms.
Among the bacterial isolates in CSOM, P. aeruginosa was the predominant organism that accounted for 62 (43.36%) cases. S. aureus was the only Gram-positive bacterial pathogen isolated in CSOM accounting for 51 (33.65%) cases [Table 2].
Antibiotic sensitivity pattern
Acute suppurative otitis media
0Of the 44 S. aureus strains, 14 (31.82%) were sensitive to Penicillin and all (100%) were methicillin-sensitive. [Table 3] shows sensitivity pattern of the isolates.
Among the isolates of P. aeruginosa, 25 (89.28%) were sensitive to third generation cephalosporins (Ceftazidime) and Piperacillin + Tazobactam. All (100%) the isolates were sensitive to Imipenem. However, only 19 (67.86%) were sensitive to Amikacin and Ciprofloxacin [Table 4].
Chronic suppurative otitis media
Among P. aeruginosa, 59 (93.16%) were sensitive to Imipenem and Ceftazidime, 58 (93.16%) were sensitive to Piperacillin + Tazobactam, 49 (79.03%) were sensitive to Ciprofl oxacin and 36 (58.06%) were sensitive to Amikacin [Table 5].
Among the isolates, 3 (21.43%) Klebsiella pneumoniae and 1 (33.37%) Escherichia More Details coli were ESBL producers and 3 (4.73%) P. aeruginosa were MBL producers.
Most common polymicrobial infection was by P. aeruginosa and S. aureus followed by P. aeruginosa and Klebsiella spp. Among the fungal pathogens, Aspergillus species formed the major isolate, that is, 25/41 (60.98%) followed by Candida with 13 (31.71%) isolates [Table 6]. Aspergillus species was also the major fungal pathogen obtained along with bacteria.
| Discussion|| |
This study was done to know the bacterial and fungal aetiological agents of otitis media, with antimicrobial susceptibility testing of the bacterial isolates. The results are compared and correlated with the studies conducted by other researchers.
Of 260 otitis media patients, 87 (33.46%) had ASOM and 173 (66.54%) had active CSOM. This shows that the incidence of CSOM is more compared to ASOM. This finding correlated with the study conducted by Oni et al. in Ibadan, Nigeria (1997). Of the 347 patients selected in their study, 67.1% cases were CSOM and 14.4% were ASOM. O.O. Olubanjo did a study on the epidemiology of ASOM in 2005 and observed the low incidence (1.01%) of ASOM.
In this study, it has been observed that in more than 50% of the cases, S. aureus was the etiological agent for ASOM. This finding correlated with studies conducted by the following researchers: Iseh and Adegbite in 2004 who observed that S. aureus (46.2%) was the most common cause followed by E. coli (23.1%) in ASOM.  Das et al., in 2005, reveals that the common microbes isolated from the culture from ASOM were S. aureus (69.2%), Streptococcus (7.7%), and P. aeruginosa (7.7%). 
In this study, it has been observed that in CSOM bacteria were more common than fungi. It was also observed that among the Gram-negative organisms P. aeruginosa was the predominant isolate accounting for 62 (43.36%) cases. S. aureus was the only Gram-positive bacterial pathogen isolated in CSOM. The above findings correlated with the following studies. A similar study was done for CSOM in our institution in 2003 by Sinha, which also showed that in CSOM P. aeruginosa was the predominant isolate followed by S. aureus. Loy et al. in 2002 conducted study on the microbiology of CSOM in Singapore and observed that P. aeruginosa was the predominant pathogen in CSOM followed by S. aureus.  Microbiological findings in patients with CSOM conducted by Nikakhlagh et al., in 2008, reveals that the most common isolate was S. aureus (32.4%) followed by P. aeruginosa (21.6%). 
Of 173 CSOM cases in the study, Aspergillus forms the major fungal pathogen 25 (14.45%), followed by Candida 13 (7.51%). The study conducted by Sinha in 2003 showed that among the fungal pathogens causing CSOM, Aspergillus spp. was the major pathogen followed by Candida albicans. A study conducted by Sreekumar et al. in the ENT Department, Medical College, Thiruvananthapuram (2007) observed that Aspergillus niger and fumigatus are the most common cause of otomycosis.  In the study conducted by Loy et al. on patients with CSOM  Aspergillus niger, Aspergillus spp. and Candida spp. were the main isolates.
Use of local and/or systemic antibiotics guided by culture and sensitivity is the effective treatment modality. This will prevent the development of drug resistance and use of unwanted antibiotics. For cases in which S. aureus was isolated, oral Cloxacillin and Gentamicin ear drops are used and in cases in which P. aeruginosa was isolated, oral Ciprofloxacin and Gentamicin ear drops were used. In the case of resistant Pseudomonas strains, local application of 1% acetic acid was very effective.
If the discharging ear does not respond to antibiotics, fungal infection should be suspected. For CSOM cases due to fungal infection insertion of gauze piece saturated with Clotrimazole, Neomycin, and Beclomethazone for 3-4 days was very effective.
In the present study, out of 173 CSOM patients, 23 had various complications. Totally, 17 had mastoiditis; four had temporal lobe abscess and one patient each had post-auricular abscess and meningitis. These cases were managed by parenteral antibiotics and surgical evacuation of pus.
| Conclusion|| |
The study of micro-organisms commonly associated with suppurative otitis media and their antibiotic susceptibility pattern is very useful for the physician to plan treatment. The aerobic bacteriological study of ASOM reveals that S. aureus is the most common causative agent followed by P. aeruginosa, K. pneumoniae, and S. pyogenes. No fungal aetiology has been identified for ASOM. The aerobic bacteriological study of CSOM reveals that P. aeruginosa is the most common causative agent followed by S. aureus, K. pneumoniae, and Proteus spp.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]