|Year : 2016 | Volume
| Issue : 2 | Page : 128-130
Clinical significance of microbial flora in middle ear infections and its implications
Pratibha M Mane1, Anuradha Basawraju2
1 Department of Microbiology, Shaheed Hasan Khan Mewati Government Medical College, Mewat, Haryana, India
2 Department of Microbiology, Mamata Medical College, Khammam, Andhra Pradesh, India
|Date of Web Publication||5-Jul-2016|
Pratibha M Mane
Department of Microbiology, Shaheed Hasan Khan Mewati Government Medical College, Nalhar, Nuh, Mewat, Haryana
Introduction: Chronic suppurative otitis media (CSOM) has a multifactorial etiology, which follows acute ear infection and leads to deafness. The present study was conducted to know the etiology and antibiotic susceptibility pattern of the isolates. Methods: Ear swabs were collected and processed as per standard procedures. Results: The organisms isolated were Pseudomonas aeruginosa, Staphylococcus aureus, coagulase negative Staphylococci, Klebsiella spp., Proteus spp., and Serratia and they showed variable susceptibility patterns. The fungi isolated were Candida spp. and Aspergillus niger. Conclusion: Proper diagnosis and selection of antibiotics reduce the damage and toxicity of the drugs.
Keywords: Antibiotic, chronic suppurative otitis media, middle ear infection, susceptibility
|How to cite this article:|
Mane PM, Basawraju A. Clinical significance of microbial flora in middle ear infections and its implications. Trop J Med Res 2016;19:128-30
| Introduction|| |
Chronic suppurative otitis media (CSOM) is an inflammation of the middle ear irrespective of the etiology or pathogenesis. CSOM is disease of multiple etiologies and is well-known for its persistence and recurrence in spite of treatment. The causes and pathogenesis of CSOM are multifactorial. CSOM is usually a sequel of acute otitis media.  CSOM is a common cause of hearing impairment in low - and middle-income countries.  The infection of the middle ear follows viral infections of the upper respiratory tract but soon invades the middle ear with pyogenic organisms. The majority of these infections is caused by bacteria. The indiscriminate, imprecise, improper, and haphazard use of antibiotics have caused the emergence of multiple resistant strains of bacteria, which can produce both primary and postoperative infections. , The increased bacterial resistance to many commonly used antibiotics is posing a serious threat to public health. The changes are occurring in the microbiological flora following the advent of sophisticated synthetic antibiotics. Hence, the importance of knowledge of the local pattern of infective organisms and their susceptibility pattern is essential to enable an efficacious treatment of this disorder. , Keeping in view the widespread use of antibiotics in the community and the high rate of resistance to antibiotics, this study was undertaken to identify the microbial profile and their antibiogram in CSOM.
| Materials and Methods|| |
A prospective study was conducted on 55 patients suffering from middle ear infections in a tertiary care hospital for a period of 3 months. Inclusion criteria were patients of all age groups suffering from ear discharge. Exclusion criteria were those who were on antibiotics. Patients' consent was taken and ethical committee clearance was obtained. Two swabs were collected before commencement of antibiotic therapy so that antibiotics did not hamper with the growth of organisms.
The external ears were cleaned with sterile swab soaked in sterile physiological saline prior to collecting the exudates. The exudates from each patient were collected by inserting a sterile swab via auditory speculum and the samples were transported to the laboratory without delay. Direct smears were prepared from the first swab and Gram staining was performed. The other swab was used for inoculation on blood agar, chocolate agar, MacConkey agar, and Sabouraud agar. The plates were incubated at 37°C for 24 h and incubation was extended for 48 h when there was no growth. The organisms were identified by cultural characters, morphology, pigment production, motility, and conventional biochemical tests.
Antibiotic sensitivity test was performed by Kirby-Bauer disc diffusion method following Clinical and Laboratory Standards Institute (CLSI) guidelines. The control tests were performed with Staphylococcus aureus ATCC-25923, Escherchia coli ATCC-25922, and Pseudomonas aeruginosa ATCC-27853. The discs used were gentamycin (10 μg), ciprofloxacin (5 μg), amikacin (30 μg), levofloxacin (5 μg), ofloxacin (5 μg), amoxycillin (10 μg), and cefixime (5 μg) (Hi - Media Laboratories, Mumbai). The plates were then incubated at 37°C overnight. The diameter of the zone of inhibition around each of the discs was measured. The results were interpreted as "sensitive," "moderately sensitive," or "resistant" to different drugs by comparing the diameters in the interpretation table.
| Results|| |
Out of the 55 cases studied, pure growth was obtained in 35 (63.3%), mixed growth in 9 (16.37%), and no growth in 11 (20%) samples. Out of 55 cases, 35 were males, 20 were females, and the age group range was 1-70 years. Various microorganisms were isolated and their sensitivity pattern is shown in [Table 1].
|Table 1: Percentage of different isolates and their antibiotic sensitivity pattern |
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| Discussion|| |
CSOM is a condition of the middle ear that is characterized by persistent or recurrent discharge through a chronic perforation of the tympanic membrane. Due to perforation of the tympanic membrane, microorganisms may gain entry to the middle ear via the external ear.  It is a destructive and persistent disease with reversible sequelae and can proceed to serious intra- and extracranial complications. Such complications were very common in the preantibiotic era. Though such serious complications are low at present, still some patients have complications ranging from persistent otorrhea, mastoiditis, labyrinthitis, and facial nerve palsy.  Even though the complications are rare, treatment should be started early and effectively to avoid and reduce the chances of complications.  The therapeutic use of antibiotics is usually started empirically prior to the results of microbiological culture. Selection of any antibiotic is influenced by its efficacy, resistance of bacteria, safety, risk of toxicity, and cost. Knowledge of the local microorganism pattern and their antibiotic sensitivity is essential to allow effective and cost-saving treatment. 
In the present study, Pseudomonas aeruginosa was the predominant organism followed by Staphylococcus aureus. It is observed that both Gram-positive and Gram-negative organisms are responsible for CSOM. These findings were correlated to the findings of Nandy et al.,  Ali et al.,  Loy et al.,  Poorey,  Perwin et al.,  Hegde,  and Oyeleke  [Table 2]. The numbers of cases caused by fungus are less in number as compared to bacteria. The pattern of organisms isolated in the tropical countries such as Africa, Singapore, Nigeria, and Pakistan is similar to studies in India. The organisms isolated in other parts of the world have a different picture. Still, Pseudomonas and Staphylococci cause the majority (65.91%) of middle ear infections in tropical countries.
|Table 2: Organisms isolated from different studies and their comparison with the present study |
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The antibiotic sensitivity pattern shows that all isolated organisms were sensitive to gentamycin, most probably due to most of the patients treated for CSOM on an outpatient department (OPD) basis, injectable drug being less commonly used, and levofloxacin. The highest degree of resistance was shown by cefixime followed by amoxycillin. Though gentamycin has some ototoxic effects, it is still the drug of choice in the treatment of CSOM as it is effective against a wide range of organisms. The microbiological spectrum varies from region to region and from time to time.
In the era of antibiotics, the emergence of antibiotic resistance is becoming more common. Also, many of the antibiotic eardrops are available over the counter and are sold without the prescription of a medical practitioner. This leads to inadvertent and irrational use of antibiotics. As soon as the symptoms subside, many patients stop taking antibiotics before the completion of therapy and allow partially resistant microbes to flourish. Such practice should be condemned strongly and people should be educated to avoid the same. Therefore, it is recommended that treatment of ear infection be done when the causative agents as well as the drug sensitivity patterns are known and properly administered. This will enhance better treatment and reduce the burden of the infection on the patients and in the long term it may reduce the cost of treatment.
Limitation of the study
The study was planned for profiling of aerobic microbial flora of the middle ear. However, there is a rare possible contamination from the external auditory canal while collection was done.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]