|Year : 2013 | Volume
| Issue : 2 | Page : 51-54
Microbiological pattern of ear swabs in chronically discharging ears in a Tertiary Care hospital in India
Raghvendra Singh Gaur1, John Mathew1, Ajoy Mathew Varghese1, George Ani Mathew1, Ramanathan Chandrasekharan1, Shalini Anandan2
1 Department of ENT Unit 2, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||15-Jun-2013|
Raghvendra Singh Gaur
304, Department of ENT Unit 2, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Aims: The aim of this study was to identify the microorganisms associated with the chronic discharging ears and their antimicrobial susceptibility pattern. To find the pattern in bacteriological flora and their susceptibility patterns in patients from the different parts of India. Settings and Design : Observational, retrospective study. Subjects and Methods : A total of 106 patients with unilateral or bilateral active chronic discharging ears attending the outpatient clinic or in-patients were included in the study. All patients' chart details were reviewed and history, clinical findings and microbiology reports were noted. Results : The microbiology of 106 samples (106 patients) was studied (in bilateral ear disease, information about the side from where the swab was taken, was not available). Among them, 72 (67.92%) grew a single isolate while 34 (32.07%) grew two or more organisms. Major micro-organism isolated was Pseudomonas aeruginosa 48 (30.96%), followed by Staphylococcus aureus 46 (29.676%), non-fermenting gram negative bacilli (NFGNB) 17 (10.96), Coliforms 22 (14.20%). Drug susceptibility pattern of P. aeruginosa showed that Piperacillin was active against the majority of the isolates 94%, followed by Ceftazidime 83.3%, Amikacin 81.2%, Netilmicin, Tobramycin 60% and Ciprofloxacin, Gentamicin, Aztreonam 62.5%. Most of the S. aureus isolates were susceptible to Oxacillin in 80% and Erythromycin in 43%. Conclusions : Commonest organisms isolated from chronically discharging ears were P. aeruginosa and S. aureus, with P. aeruginosa marginally more than S. aureus. When patients from north and south were segregated, majority of isolates were P. aeruginosa in south (P. aeruginosa 28, S. aureus 23), whereas S. aureus was more in north (23 S. aureus, 20 P. aeruginosa). Coliforms were isolated more in south (13 south, 9 in north), similarly, NFGNB were also more in south (11 south, 6 north). Majority of isolates of P. aeruginosa were susceptible to Piperacillin and S. aureus was susceptible to Oxacillin.
Keywords: Bacteriology, Chronic otitis media, Different parts of India, Susceptibility
|How to cite this article:|
Gaur RS, Mathew J, Varghese AM, Mathew GA, Chandrasekharan R, Anandan S. Microbiological pattern of ear swabs in chronically discharging ears in a Tertiary Care hospital in India. Indian J Otol 2013;19:51-4
|How to cite this URL:|
Gaur RS, Mathew J, Varghese AM, Mathew GA, Chandrasekharan R, Anandan S. Microbiological pattern of ear swabs in chronically discharging ears in a Tertiary Care hospital in India. Indian J Otol [serial online] 2013 [cited 2019 Jul 21];19:51-4. Available from: http://www.indianjotol.org/text.asp?2013/19/2/51/113501
| Introduction|| |
Chronic otitis media (COM) may result in permanently disabling and potentially fatal complications which can have a profound impact on the society, in terms of resources utilized in treatment of the disease and rehabilitation. ,,,, The organisms isolated in COM can be aerobes, anaerobes, mixed or Fungi. Individual isolates and percentages differ from study to study. ,,
In a discharging ear both topical and systemic therapy is employed to control the infection. , Choice of systemic therapy depends on the organism isolated in the culture.  Our study is aimed at finding the local pattern of microbes and their antimicrobial susceptibility pattern in cases of COM to provide a guideline for empirical antibiotic therapy.
| Subjects and Methods|| |
This study is a retrospective observational study conducted in Tertiary Care Center in India. 106 patients of COM who presented to the ear, nose, and throat department from April 2011 to April 2012 were studied. Details of the history and examination findings were verified from the records. All patients who had active ear discharge for more than 3 months duration were included in the study. Patients, who had otomycosis or malignancy in the ear, at the time of presentation were excluded.
Single use commercially available cotton swabs were used to collect pus. Utmost care was taken to avoid surface contamination and the swabs were sent to the microbiology laboratory for further processing. The pus swabs were cultured on the blood, chocolate and MacConkey's agar and incubated at 37°C for 24-48 h. The blood and chocolate agar plates were incubated in a CO2 incubator. All organisms isolated were identified according to the standard microbiological methods. Antimicrobial susceptibility tests were performed using Kirby-Bauer disc diffusion method. The standard antimicrobial discs used for Staphylococcus aureus were Oxacillin 1 μg and Erythromycin 15 μg. The standard antimicrobial discs used for Pseudomonas aeruginosa were Gentamicin 10 μg, Amikacin 30 μg, Ciprofloxacin 5 μg, Ceftazidime 30 μg, Piperacillin/Tazobactam 100/10, 110 μg, Levofloxacin 5 μg, and Netilmicin 30 μg.
| Results|| |
There were a total of 106 patients included in the study. Age ranged from 8 years to 83 years. There was a slight male preponderance, 62:44.
Single organism was isolated in 72 patients (67.92%), while 34 (32.07%) showed mixed cultures. The most common organism isolated was P. aeruginosa 48 (30.96%) followed by S. aureus 46 (29.67%). Coliforms were isolated in 22 patients (14.2%). Methicillin resistant S. aureus isolation rates were 8 in numbers.
Data segregation was carried out between south and north. Out of 48 cases with P. aeruginosa infection, 28 (18.06%) were from the south of India and 20 (12.9%) from north. For S. aureus data from the south and north of India was 23 (14.83%) each. For Coliforms 13 (8.34%) were from south and 9 (5.81%) from north. Non-fermenting gram negative bacilli (NFGNB) 12 (9.67%) were from south and 5 (3.22%) from north.
In total, P. aeruginosa [Table 1] were susceptible to Piperacillin in 94% (95% south and 92.36% north) of cases, Ceftazidime in 83.3% (82% in south and 85% north) and Amikacin in 81.2% (75% south and 90% north), Levofloxacin in 51% (40% in the south and 69% in north) Netilmicin and Tobramycin in 63.3% each (50% in south and 84.6% in north) Aztreonam 62.5% (70% in south and 83.5% in north), Ciprofloxacin and Gentamicin 62.5% each (50% in south and 66% in north).
Drug susceptibility pattern for S. aureus [Table 2] showed that 80% of the total isolates were susceptible to Oxacillin, of which south was 82.6% and north was 78%, whereas only 43% of isolates were susceptible to Erythromycin of which 56.5% in south and 30.4% in north. Out of 17 NFGNB [Table 3]a isolates, 15 specimens susceptibility were carried out and for the rest of two specimens special sensitivity were asked. In 15 specimens total 93.34% of NFGNB were susceptible for the Piperacillin (south 90%, north 100%), 80% for Ceftazidime (south 90%, north 60), and 66.67% each for Amikacin, Levofloxacin, Netilmicin and Tobramycin (south 70% north 60%).
For Coliforms, [Table 3]b only 22.74% samples were susceptible for Amox/clav (30.76% in south and 11.11% in the north) and 27.28% samples were susceptible for Ampicillin (38.46% in south and 11.11% in north).
| Discussion|| |
Otologists, pediatricians, and general practitioners commonly see COM and its complications. Early bacteriological diagnosis of all cases will assure accurate and appropriate effective therapy. For selection and prescription of antibiotics, antibiotic efficacy, bacterial resistance, safety, risk of toxicity and the cost is to be considered. Biofilm formation is emerging as a factor for persistence of the infection. Biofilms consist of communities or groups of microorganisms that attach to the surfaces of animate objects such as heart valves, bones or tissues or to inanimate objects such as artificial heart valves and prosthetic implants. Knowledge of the local microbial scenario and the antibiotic susceptibility pattern is essential to formulate a protocol for empirical antibiotic therapy.
Studies of microbiology of chronic discharging ears have revealed that the most frequently isolated bacteria were P. aeruginosa (31.1%), S. aureus (19.1%), Proteus sp (7.7%), Klebsiella sp (1%) and Fungi.  Review of literature of bacterial flora in CSOM in different states of India showed P. aeruginosa as the main isolate. Isolation rates of S. aureus in one of the study was low when compared to that of other gram negative rods like Klebsiella, Escherichia More Details coli and Proteus which was relatively high. ,
Our study also revealed that P. aeruginosa (30.96%) was the most common isolate in COM followed by S. aureus (29.65%). There were no fungal isolates in our cases and anaerobic culture was not carried out. In this study, we found that P. aeruginosa and S. aureus together accounted for almost 60% of the total bacterial isolates. P. aeruginosa was the most common organism isolated in south (18.06%) while S. aureus in north (14.83%). Coliforms (i.e., Klebsiella, E. coli, Enterobacter and Citrobacter) were relatively high (14.2%) following P. aeruginosa and S. aureus.  These Coliforms are more frequently isolated from south (8.34%) compared to the north (5.81%). NFGNB were also more commonly isolated from south (9.67%) than north (3.22%). Study done in Malawi shows most common organisms isolated were Proteus (74%) and Enterococci (60%). 
Antimicrobial susceptibility of P. aeruginosa in our study revealed that 94% isolates were susceptible to Piperacillin while 83% of isolates were susceptible to Ceftazidime, 81% susceptible to Amikacin and 63% to Ciprofloxacin, Tobramycin, Gentamicin and Aztreonam. Globally, a change has been noticed in the susceptibility of P. aeruginosa towards Quinolones in the last few decades. One study carried out in 1996 in Turkey revealed only six% of P. aeruginosa isolates to be resistant to Ciprofloxacin,  where as in South Korea in a study carried out in 2004 Ciprofloxacin resistance was noted in 100% of the isolates.  In contrast our study has shown 62.5% of isolates to be susceptible to Ciprofloxacin. A study done in Singapore,  has shown significantly higher percentage of P. aeruginosa isolates susceptible to Gentamicin when compared to ours. With these type of results in the present era the otorhinolaryngologist has to depend on the Ciprofloxacin oral preparations to treat P. aeruginosa, though the organism is retaining its susceptibility to higher antibiotics that are available in injectable form and can be prescribed in complicated forms of P. aeruginosa infection.
While for S. aureus 80% of the isolates were susceptible to Oxacillin and only 43% were susceptible to Erythromycin.
Susceptibility patterns of NFGNB and Coliforms were not encouraging with respect to the conventional antibiotics and needed susceptibility with a second line of antibiotics carried out. However, since this study involved small numbers of isolates special susceptibility tests were not carried out.
The declining susceptibility trend may be due to a number of factors including injudicious use and inappropriate dosage and easy access to antimicrobials as well as the organism developing resistance to Quinolones.
| Conclusion|| |
P. aeruginosa was the most common isolate followed by S. aureus. Coliforms bacterial isolates were more compared to other studies and needs further study to find out the cause. Susceptibility of P. aeruginosa isolates showed good susceptibility to Piperacillin, Ceftazidime, Amikacin and 62% susceptibility to Ciprofloxacin. S. aureus were susceptible to Oxacillin in 80% of isolates. Looking at our results, there are differences in organism isolated from a different region and they have different susceptibility pattern as well. This suggests the growing misuse of the antibiotics along with other factors is leading to change in the susceptibility pattern.
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[Table 1], [Table 2], [Table 3]
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