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Year : 2012  |  Volume : 18  |  Issue : 3  |  Page : 136-139

Study of aerobic bacterial isolates and their antibiotic susceptibility pattern in chronic suppurative otitis media

Department of Microbiology, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda, Andhra Pradesh, India

Date of Web Publication12-Nov-2012

Correspondence Address:
Sateesh Kumar Malkappa
Department of Microbiology, Kamineni Institute of Medical Sciences, Narketpally, Nalgonda, Andhra Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-7749.103440

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Background : Chronic suppurative otitis media (CSOM) is a disease of multiple etiology and its importance lies in its chronicity and dreaded complications. Both Gram positive and negative organisms are responsible for infection of the middle ear. Due to advent of newer and sophisticated antibiotics, the microbiological flora is changing constantly. This requires a reappraisal of the flora in CSOM and their in vitro antibiotic sensitivity pattern in cases of CSOM, which do not respond to local antibiotics. The frequent presence of CSOM in general practice and its poor response to the routine treatment are the factors responsible for undertaking this study. Materials and Methods : One hundred and twenty six patients with CSOM were prospectively studied. They had chronic ear discharge and had not received antibiotics for the previous five days. Swabs were taken and cultured for bacteria. The standard method of isolation and identification was followed. Antimicrobial susceptibility of the bacterial isolates was performed by Kirby-Bauer's disc diffusion method. Results: Analysis of bacterial flora of the present study showed predominance of Gram negative bacilli (69.84%). The highest incidence (45.24%) was that of Pseudomonas aeruginosa followed by Staphylococcus aureus (22.22%). Amikacin was found to be the most effective drug. Conclusion: This study suggests that the common etiological agents for CSOM were Pseudomonas aeruginosa followed by Staphylococcus aureus. Amikacin was found to be the drug of choice.

Keywords: Aerobic bacterial isolates, Antibiotic resistance, Chronic otitis media

How to cite this article:
Malkappa SK, Kondapaneni S, Surpam RB, Chakraverti TK. Study of aerobic bacterial isolates and their antibiotic susceptibility pattern in chronic suppurative otitis media. Indian J Otol 2012;18:136-9

How to cite this URL:
Malkappa SK, Kondapaneni S, Surpam RB, Chakraverti TK. Study of aerobic bacterial isolates and their antibiotic susceptibility pattern in chronic suppurative otitis media. Indian J Otol [serial online] 2012 [cited 2023 Mar 29];18:136-9. Available from: https://www.indianjotol.org/text.asp?2012/18/3/136/103440

  Introduction Top

Chronic suppurative otitis media (CSOM) is a disease of multiple etiology and is well known for its persistence and recurrence, despite treatment. CSOM is a destructive disease with irreversible sequelae and can proceed to serious intra and or extra cranial complications. [1] The microbiological flora of the middle ear varies and depends on the type of otitis media. In the acute form, the major organisms present are Hemophilus influenzae, Streptococcus pneumoniae, Pseudomonas aeruginosa and anerobic bacteria. [2] CSOM has received considerable attention, not only because of its high incidence and chronicity, but also because of issues such as bacterial resistance and ototoxicity with both topical and systemic antibiotics. [2] The wide spread use of antibiotics has precipitated the emergence of multiple resistant strains of bacteria which can produce both primary and post-operative ear infections. The indiscriminate, haphazard and hay-hearted use of antibiotics and the poor follow up of the patients have resulted in the persistence of low-grade infections. The changes in the microbiological flora following the advent of sophisticated synthetic antibiotics have increased the relevance of the reappraisal of the modern day flora in CSOM, and their in-vitro antibiotic sensitivity pattern is very important for the clinician to plan a general outline of treatment for a patient and can minimize complications that may require surgery for a chronically discharging ear. [3] The study of bacteriology and drug sensitivity is necessary to enable the treating family physician to plan the general management of CSOM and it is almost essential for the ENT surgeon to make the discharging ear dry for better results of myringoplasty and ossiculoplasty. [4] The objective of this study is to determine the etiological agents and their antibiotic susceptibility pattern in CSOM patients for appropriate treatment.

  Materials and Methods Top

One hundred and thirty patients, who presented to the ENT department from Aug 2010 to Aug 2011, with a history of chronic discharging ear, were prospectively studied. Two sterile cotton swabs were used to collect ear discharge from CSOM patients. Only those cases were selected who had not taken any treatment either systemic or local in the form of ear drops for the last seven days. One swab was used for performing Grams' stain and second one for culture. Culture was done on blood agar and MacConkey agar. The organisms were identified by culture characters, morphology, and pigment production, beta hemolysis on blood agar, motility and conventional biochemical tests. Antimicrobial susceptibility test for all isolates was performed on Mueller Hinton agar plate using Kirby Bauer disc diffusion method. Antibiotic discs were procured from HIMEDIA labs Mumbai. Results were interpreted using Clinical Laboratory Standards Institute (CLSI) guidelines. [5]

  Results Top

Out of 130 samples from patients enrolled in the study, 126 (96.92%) samples were culture positive. The most common organisms isolated were Pseudomonas aeruginosa 57 (45.24%) and Staphylococcus aureus 28 (22.22%) followed by other enterobacteriaceae members like Klebsiella Escherichia coli and Proteus spp. Details of various isolates from CSOM samples are depicted in [Table 1]. No growth was observed in 4 (3.08%) samples.
Table 1: Organisms isolated from CSOM samples (N = 126)

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Amikacin was the most effective antibiotic in the present study. It was effective against maximum number of strains (82.37%), followed by Ciprofloxacin (76.62%), Cefaperazone (75.83%), and Gentamicin (71.4%), Ceftazidime 76 (65.16%) [Table 2].
Table 2: Percentage antibiotic resistance patterns of isolates from CSOM

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  Discussion Top

CSOM is a condition of the middle ear that is characterized by persistent or recurrent discharge through a chronic perforation of the tympanic membrane. Untreated cases of CSOM can result in a broad range of complications. Four (3.08%) samples were sterile in present study. This is in comparison with the results found by Kumar et al., [6] (4.39%) and Vijaya et al., [7] (5.28%), while Chakraboty et al., [8] (12.6%), Vijaya et al., [7] (17.6%), and Fatma et al., [9] (16.9%) found higher percentage of sterile samples. This may be due to prior antibiotic therapy. All samples in the present study yielded single type of organism. Kumar et al., [6] and Fatma et al., [9] also reported 93.1 and 94% of monobacterial growth in their studies, respectively, while Vijaya (1998) [10] reported only in 51% of samples.

Our results show that active CSOM infection is mainly due to Pseudomonas aeruginosa (45.24%) and Staphylococcus aureus (22.22%). The third most commonly isolated organism, coagulase negative Staphylococcus, may represent skin flora contamination, and not be a true pathogen. This finding is in tandem with the pattern of CSOM infection within the tropical region. It is seen that both Gram positive and Gram negative organisms are responsible for infection of middle ear. It is usually seen that Gram negative rods outnumber the Gram positive organism in CSOM In the present study, Pseudomonas aeruginosa was the predominant organism followed by Klebsiella. These findings are in accordance with those of many previous authors, [6],[8],[9],[11],[12] A H C Loy (2002), [13] Lakshmipathi and Bhaskaran (1965), [14] Gulati et al., [15] Ayyagari et al., [16] while Vijaya et al. [17] found Klebsiella as the predominant isolate in CSOM cases. The findings of predominant Gram negative bacilli is consistent with many previous investigators [6],[8],[11],[12],[18] Gulati et al., [15] Rajendra Kumar (1975), [19] Gulati et al., [20] Mishra et al., [21] while studies conducted by various investigators [Table 3], [4],[7],[10],[17],[22] Singh and Bhaskar (1972), [23] Rao et al., [24] Rao and Reddy (1994), [25] Friedmann (1957), [26] found Staphylococcus aureus to be the most common causative organism, [1] which is the second common isolate in our study. All the pathogenic strains isolated in the present series were tested against various antibiotics. 90% of isolates showed resistance to amoxicillin. Kumar et al. [6] and Chakraborty et al. [8] also reported 95.40% of resistance to amoxicillin among CSOM isolates. 40-50% of Pseudomonas aeruginosa isolates have shown resistance to pipercillin, ceftazidime, Ampicillin, but sensitivity was moderately good for Gentamicin, and ciprofloxacin. All other Isolates are sensitive to routinely used antibiotics. Amikacin was found to be the most effective drug followed by Gentamicin, Ciprofloxacin, and Cefoperazone. These findings are in accordance with those of Gulati et al., [20] and Mishra et al. [21] S.aureus was fairly sensitive to erythromycin, gentamicin and ciprofloxacin. This is in comparison with the reports of Hegde et al. [12] and Goyal et al. [11] In the present study, gentamicin with fair susceptibility pattern is more effective in treating CSOM as majority of pathogens in CSOM cases are susceptible to it. When used topically, gentamicin induced ototoxicity is rare. [12] When the results of various workers were compared, one fact became obvious that the bacteriology and antibiotic sensitivity pattern of CSOM has been changing from time to time. The strains of yesterday which were sensitive to Streptomycin, Tetracycline and Chloramphenicol no longer exhibit the old sensitivity pattern today. These drugs have been replaced by aminoglycosides, quinolones and cephalosporins. [1]
Table 3: Occurrence of various pathogenic organisms in patients of CSOM from various studies

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Pseudomonas continues to remain supreme as primary offender and poses problem for effective therapeutic control. [11] Staphylococcus aureus bear the inherent trait of resistance. In the era of antibiotics, the emergence of antibiotic resistance is becoming more common. Patient non-compliance is an important factor responsible for the development of antibiotic resistance. As soon as symptoms subside, many patients stop taking antibiotics before completion of therapy and allow partially resistant microbes to flourish. Such practice should be condemned strongly and patients should be educated to avoid the same.

For the antibiotics commonly available locally as topical eardrops, gentamicin and ciprofloxacin were shown to be the most effective, with good sensitivities for the commonly isolated organisms. With specific regard to the two most common pathogens in CSOM, Pseudomonas aeruginosa was found to be more resistant to commonly used antibiotics, while Staphylococcus aureus showed moderately good sensitivity to all antibiotics tested. Gentamicin eardrops thus appear to be an effective first-line topical antibiotic in the treatment of active CSOM. [13]

  Conclusion Top

Knowledge of the pathogens and antibiotic sensitivity pattern responsible for CSOM and choosing suitable antibiotics according to susceptibility tests should guide the management of disease treatment and reduces intracranial and extra cranial complications with CSOM.

  References Top

1.Poorey VK, Arati Iyer. Study of bacterial flora in CSOM and its clinical significance. Indian J Otolaryngol Head Neck Surg 2002;54:91-5.  Back to cited text no. 1
2.NikakhlaghS AD, Khosravi A, Fazlipour M, Safarzadeh N. Rashidi Microbiologic findings in patients with chronic suppurative otitis media. J Med Sci 2008;8:503-6.  Back to cited text no. 2
3.Kumar H, Seth S. Bacterial and fungal study of 100 cases of chronic suppurative otitis media. J Clin Diagn Res 2011;5:1224-7.  Back to cited text no. 3
4.Taneja MK. CSOM: A bacteriological study. Indian J Otol 1995;1:24-7.  Back to cited text no. 4
5.National Committee for Clinical Laboratory Standards. Performance Standards for Antimicrobial Susceptibility Testing. Wayne, PA, USA: NCCLS; 2001. p. M100-S1.  Back to cited text no. 5
6.Kumar S, Sharma R, Saxena AK, Pandey A, Gautam P, Jain R. A study of bacterial flora and sensitivity to antibiotics in cases of CSOM TTD in western UP. Indian J Otol 2008;14:20-4.  Back to cited text no. 6
7.Vijaya D, Nagarathnamma T. Microbiological study of chronic suppurative otitis media. Indian J Otol 1998;4:172-4.  Back to cited text no. 7
8.Chakraborty A, Bhattacharjee A, Purkaystha P. Microbiological profile of chronic suppurative otitis media: Its significance in North-East India. Indian J Otol 2005;11:39-44.  Back to cited text no. 8
9.Fatma AA, Assiry S, Siraj MZ. Microbiological evaluation and aspects on management of chronic suppurative otitis media in Riyadh. Indian J Otol 1998;4:115-20.  Back to cited text no. 9
10.Vijaya D. Aerobes, anaerobes, and fungi in chronic suppurative otitis media. Indian J Otol 2000;6:55-8.  Back to cited text no. 10
11.Goyal R, Aher A, De S, Kumar A. Chronic suppurative otitis media-A clinico microbiological study. Indian J Otol 2009;15:18-22.  Back to cited text no. 11
12.Hegde MC, Bhat GK, Sreedharan S, Ninan GP. Bacteriological study of tubotympanic type of chronic suppurative otitis media. Indian J Otol 2005;11:13-6.  Back to cited text no. 12
13.Loy AH, Tan AL, Lu PK. Microbiology of chronic suppurative otitis media in Singapore. Singapore Med J 2002;43:296-9.  Back to cited text no. 13
14.Lakshmipathi G, Bhaskaran CS. Bacteriology of chronic suppurative otitis media. J Indian Med Assoc 1965;45:436-40.  Back to cited text no. 14
15.Gulati J, Tandon PL, Singh W, Bais AS. Study of bacterial flora in chronic suppurative otitis media. Indian J Otolaryngol Head Neck Surg 1969;2:198-202.  Back to cited text no. 15
16.Ayyagari A, Pancholi VK, Pandhi SC, Goswami A, Aggarwal KC. Anaerobic bacteria in chronic otitis media. Indian J Med Res 1981;73:860-5.  Back to cited text no. 16
17.Vijaya D, Geeta SH. Microbiological study of discarging otitis media. Indian J Otol 2003;9:17-9.  Back to cited text no. 17
18.Naheed P, Khan Z, Khan IM, Suhail AS, Zuber A. Bacteriological study of patients with discharging otitis media-A rural study. Indian J Otol 2003;9:29-32.  Back to cited text no. 18
19.Rajendra Kumar PV. A study on the incidence and aetiology of deafness in a south Indian population. Indian J Otolaryngol Head Neck Surg 1974;26:153-7.  Back to cited text no. 19
20.Gulati SK. Investigative profile in patients of chronic suppurative otitis media. Indian J Otol 1997;3:59-62.  Back to cited text no. 20
21.Anupam M, Girish S, Devika N, Chandra MS. Bacteriological study of chronic suppurative otitis media. Indian J Otol 1999;5:87-91.  Back to cited text no. 21
22.Kuchal V. Antibiotic sensitivity pattern in chronic suppurative otitis media (Tubotympani type) in Kumoun region. Indian J Otol 2010;16:17-21.  Back to cited text no. 22
23.Singh N, Bhaskar R. Microbiological study of otitis media. Indian J Otolaryngol Head Neck Surg 1972;24:161.  Back to cited text no. 23
24.Rao MV, Jayakar PA. Bacteriological study of CSOM. J Indian Med Assoc 1980;75:30-4.  Back to cited text no. 24
25.Rao BN, Reddy MS. Chronic suppurative otitis media - A prospective study. Indian J Otolaryngol Head Neck Surg 1994;3:72-7.  Back to cited text no. 25
26.Friedmann I. The pathology of acute and chronic infections of the middle ear cleft. Ann Otol Rhinol Laryngol 1971;80:391-6.  Back to cited text no. 26


  [Table 1], [Table 2], [Table 3]

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