Abstract
The bacteriological and antimicrobial sensitivity profile of chronic otitis media (COM) varies from region to region and from time to time and may vary among different age group as well. It was against this backdrop of the changing bacteriological profile and sensitivity pattern together with the paucity of categorically separated data of pediatric and adult population, that the present study was undertaken. A total of 193 patients of clinical diagnosis of cholesteatomatous COM with ear discharge and positive culture results were included in the study. Pus sample was collected under aseptic conditions and cultured on solid media and broth. Isolates were identified via standard biochemical tests and sensitivity patterns analysed. Chi square (χ2) test was used to analyse the significance. Pseudomonas was the most common isolate in both the pediatric (37.80%) and adult (51.46%) population. Methicillin sensitive staph aureus (MSSA) was found exclusively in pediatric population (p = 0.003).Piperacillin–Tazobactam combination was the single most effective drug regimen overall. 75% of pseudomonas isolates in pediatric and 87.5% in adults were sensitive to this regimen in vitro. Amikacin was the next most effective drug with 56.69% sensitivity in pediatric and 64.08% sensitivity in adult population. The present study finds piperacillin–tazobactam as the most effective therapy and pseudomonas as the most common isolate in the study population.In order to address the varying and changing bacteriological and sensitivity profile of chronic otitis media occurring among different geographical regions and also within a region over time, the authors recommend its periodic evaluation.
Keywords: Ear discharge, Cholesteatomatous otitis media, Microbial floras, Antibiotic sensitivity, Pediatric and adult population
Introduction
Chronic Otitis Media (COM) is the chronic inflammation of middle ear cleft. The disease predominantly affects younger age groups. If not managed timely and appropriately it results in destructive and irreversible sequelae [1–4], making the most common cause of childhood hearing impairment in developing countries [5]. Hearing loss in early childhood has devastating effects in different domains of a child’s life, impairing language development and thus retards the learning process. This in turn, brings with it social isolation which then adversely affects the child’s mental health. Moreover there is always a possibility of life threatening complications in untreated COM. These complications although seen in both types of COM that is, without cholesteatoma and with cholesteatoma, they are much more common in the latter. Contrary to the widely held opinion that it is the cholesteatoma causing the complications, evidence suggests that the primary role in bone erosion resulting in these complications is that of inflammation secondary to infection [6, 7], so along with surgery, precise institution of antibiotic therapy in a timely manner is essential in managing the disease and preventing complications. The bacteriology and antibiotic sensitivity patterns of COM changes from time to time and from one region to the other [8, 9]. It therefore becomes imperative to evaluate and document the ‘antibiogram’ from time to time even in the same geographical region as there is possibility of microbial flora and its sensitivity patterns to change with increasing duration of disease and also with the prolonged indiscriminate use of antibiotics. This would mean that a patient presenting in childhood and another patient presenting in adulthood might have a different bacteriology and sensitivity profile. This in turn, warrants the need to categorize the analysis into pediatric and adult groups. Most of the literature on the subject lacks this categorical separation. It was against this backdrop of severe complications of COM and its physical and psychosocial consequences as well as the changing bacteriological profile and sensitivity pattern together with the paucity of categorically separated data that the present study was undertaken.
Methods
This study was undertaken at a tertiary care teaching hospital of northern India between November 2016 and February 2020.
Inclusion Criteria
Proven cases of unilateral or bilateral ear discharge with cholesteatoma.
Patients of cholesteatomatous otitis media with positive ear swab culture and sensitivity results.
Exclusion Criteria
Patients with COM without cholesteatoma.
Patients of cholesteatomatous otitis media who received systemic or topical antibiotic treatment over past 1 week.
Patients of cholesteatomatous otitis media suffering from immunodeficiency disorders/ malignancies and receiving steroids, chemotherapy or radiotherapy.
Thus after obtaining consent, a total of 193 patients were studied.
Ear swabs were collected under aseptic precaution with sterile cotton swab sticks and were inoculated on 5% sheep blood agar, chocolate agar, Mac Conkey’s agar and thioglycolate broth and incubated at 37 degrees in 5% CO2 environment. Culture plates were evaluated for growth after 24 h and if no growth was seen then subculture with broth was done on blood and Mac Conkey’s media.
Cultured bacteria were then identified via standard biochemical tests and sensitivity patterns were analyzed as per Clinical and Laboratory Standards Institute (CLSI) guidelines.
Statistical analysis wherever applicable was done by using Chi-square test (χ2) and p- value < 0.05 was considered to be statistically significant.
Results
Clinical Profile
A total of 193 patients were included in the study based on preset inclusion and exclusion criteria. These patients were then grouped into a pediatric group comprising up to 18 years of age and an adult group of more than 18 years of age. Mean age in the pediatric age group was 10.88 years while in the adult age group was 28.54 years. The youngest patient in pediatric group was a 3 year-old female while oldest patient in adult population was a 54 year-old male.
In the pediatric age group males outnumbered females with a male to female ratio of 1:0.65 while in adults it was the other way round with a male to female ratio of 1:1.12.
Pediatric population comprises of 104 patients out of which 99 patients presented with a unilateral ear discharge while 5 presented with bilateral ear discharge. However in adult category there were a total of 89 patients among them, 86 patients (96.63%) presented with unilateral ear discharge while 3 patients (3.37%) presented with bilateral ear discharge (Table1).
Table 1.
Age and sex-wise distribution of the patients
| Age (years) | Male | Female | Male: female* | Unilateral ear | Bilateral ears | |
|---|---|---|---|---|---|---|
| Pediatric age total-104 | 03–18 Mean-10.88 | 63 (60.58%) | 41 (39.42%) | 1:0.65 | 99 (95.20%) | 5 (4.80%) |
| Older-age total-89 | > 18–54 Mean–28.54 | 42 (47.20%) | 47 (52.80%) | 1:1.12 | 86 (96.63%) | 3 (3.37%) |
*p = 0.06, 95% Confidence limit
Microbiology and Sensitivty Pattern
Pediatric Population
Eight species of microorganisms were isolated from these patients with a total of 127 isolates comprising 92 monomicrobials and 35 polymicrobials. Pseudomonas was the most common isolate constituting 37.8% (Table 2). This was followed by Proteus species (20.47%) and Methicillin Resistant Staphylococcus aureus (MRSA) (9.45%).
Table 2.
Microbial flora isolated in pediatric and older age groups patients
| Organism | Age-group | No. of culture isolates | Percentage (%) | Monomicrobial | Polymicrobial |
|---|---|---|---|---|---|
| Pseudomonas sp.* | P* | 48 | 37.80 | 37 (77.08%) | 11 (22.92%) |
| O* | 53 | 51.46 | 44 (83.02%) | 9 (16.98%) | |
| Proteus sp. | P | 26 | 20.47 | 21 (80.77%) | 5 (19.23%) |
| O | 10 | 9.71 | 8 (80%) | 2 (20%) | |
| MRSA | P | 12 | 9.45 | 10 (83.33%) | 2 (16.67%) |
| O | 7 | 6.80 | 5 (71.43%) | 2 (28.57%) | |
| Klebsiella | P | 6 | 4.72 | 5 (83.33%) | 1 (16.67%) |
| O | 8 | 7.77 | 4 (50%) | 4 (50%) | |
| E.coli | P | 10 | 7.87 | 4 (40%) | 6 (60%) |
| O | 3 | 2.91 | 3 (100%) | – | |
| Enterococci sp | P | 8 | 6.30 | 4 (50%) | 4 (50%) |
| O | 4 | 3.88 | 2 (50%) | 2 (50%) | |
| Citrobacter sp. | P | 7 | 5.51 | 4 (57.14%) | 3 (42.86%) |
| O | 16 | 15.53 | 13 (81.25%) | 3 (18.75%) | |
| MSSA** | P** | 10 | 7.87 | 7 (70%) | 3 (30%) |
| O | – | – | – | – | |
| Acinetobacter | P | – | – | – | – |
| O | 1 | 0.97% | 1 (100%) | – | |
| P. rettegri | P | – | – | – | – |
| O | 1 | 0.97% | 1 (100) | – |
P Pediatric-age group (Total flora = 127), O Older-age group (Total flora = 103)
*p-value = 0.038, **p-value = 0.003
For Pseudomonas species, piperacillin with tazobactam combination was the most effective having a sensitivity of 75%.Aminoglycosides were the next most effective drugs with amikacin and gentamycin having a sensitivity of 56.25% and 52.08% respectively. Proteus species showed a sensitivity of 84.62% to piperacillin–tazobactum and 57.69% sensitivity to amikacin. MRSA was the isolate in 9.45% of the cases and showed a sensitivity of 91.67% to vancomycin (Table 3).
Table 3.
Antibiotics sensitivities of individual microbial flora in pediatric population
| 0rganism | Amk | Gen | Pit | Azt | Ctr | Ctz | Cfs | cfx | Cpm | Cts | mrp | imp | Cld | Col | Lev | Cot | Amc | Tg | Tb | DOX | Cef | Azm | V | HG | HS | Mn |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (1) Pseudomonas total = 48 | 27 | 25 | 36 | 26 | – | 17 | – | 1 | 16 | – | 21 | 4 | – | 14 | 19 | – | – | – | 1 | – | – | – | – | – | – | – |
| Percentage (%) | 56.25 | 52.08 | 75 | 54.17 | – | 35.41 | – | 2.08 | 33.33 | – | 43.75 | 8.33 | – | 29.16 | 39.58 | – | – | – | 2.08 | – | – | – | – | – | – | – |
| (2) Proteus sp. total = 26 | 15 | 1 | 22 | – | 13 | 1 | 13 | 15 | – | 4 | 16 | 1 | – | – | 13 | 6 | 3 | 1 | – | – | – | – | – | – | – | – |
| Percentage (%) | 57.69 | 3.84 | 84.62 | – | 50 | 3.84 | 50 | 57.69 | – | 15.38 | 61.53 | 3.84 | – | – | 50 | 23.07 | 11.54 | 3.84 | – | – | – | – | – | – | – | – |
| (3) MRSA total = 12 | 6 | – | – | – | – | – | – | – | – | – | – | – | 4 | – | 2 | 5 | – | – | – | – | – | 3 | 11 | – | – | – |
| Percentage (%) | 50 | – | – | – | – | – | – | – | – | – | – | – | 33.33 | – | 16.67 | 41.67 | – | – | – | – | – | 25 | 91.67 | – | – | – |
| (4) MSSA total = 10 | 9 | – | – | – | – | – | – | – | – | – | – | – | 8 | – | 5 | 5 | 1 | – | 10 | 7 | 1 | – | – | – | ||
| Percentage (%) | 90 | – | – | – | – | – | – | – | – | – | – | – | 80 | – | 50 | 50 | 10 | – | – | – | 100 | 70 | 10 | – | – | – |
| (5) Escherchia coli total = 10 | 7 | – | 9 | – | 5 | – | 5 | 2 | 2 | 2 | 6 | – | – | – | 3 | 4 | 1 | – | – | – | – | – | – | – | – | – |
| Percentage (%) | 70 | – | 90 | – | 50 | – | 50 | 20 | 20 | 20 | 60 | – | – | – | 30 | 40 | 10 | – | – | – | – | – | – | – | – | – |
| (6) Enterococci total = 8 | – | – | – | – | – | – | – | – | – | – | – | – | 2 | – | 4 | – | – | – | – | 7 | – | 1 | 8 | 8 | 6 | – |
| Percentage (%) | – | – | – | – | – | – | – | – | – | – | – | – | 25 | – | 50 | – | – | – | – | 87.5 | – | 12.5 | 100 | 100 | 75 | – |
| (7) Citrobacter sp. total = 7 | 4 | 2 | 6 | – | 4 | – | 5 | 1 | – | – | 5 | – | – | – | 2 | 1 | – | 1 | – | – | – | – | – | – | – | 1 |
| Percentage (%) | 57.14 | 28.57 | 85.71 | – | 57.14 | – | 71.42 | 14.29 | – | – | 71.42 | – | – | – | 28.57 | 14.29 | – | 14.29 | – | – | – | – | – | – | – | 14.29 |
| (8) Kleibsella sp. total = 6 | 4 | 1 | 4 | – | 2 | – | 3 | 2 | – | 1 | 3 | 1 | – | 1 | 5 | 3 | 1 | 1 | – | – | – | – | – | – | – | – |
| Percentage (%) | 66.67 | 16.66 | 66.67 | – | 33.33 | – | 50 | 33.33 | – | 16.66 | 50 | 16.66 | – | 16.66 | 83.33 | 50 | 16.66 | 16.66 | – | – | – | – | – | – | – | – |
Amk Amikacin, Gen Gentamicin, Pit Piperacillin + Tazobactum, Azt Aztreonam, Ctr Ceftriaxone, Ctz Ceftazidime, Cfs Cefperazone + Sulbactum, Cfx Cefixime, Cpm Cefpime, Cts Ceftriaxone + Sulbactum, Mrp Meropenem, Imp Imipenem, Cld Clindamycin, Col Colistin, Lev Levofloxacin, Cot Cotrimoxazole, Amc Amoxycillin + Clavulanic Acid, Tg Tigecycline, Tb Tobramycin, Dox Doxycycline, Cef Cefoxitin, Azm Azithromycin, V Vancomycin, HG High content Gentamicin, HS High content Streptomycin, Mn Minocycline, Resistant/ Not tested
It was observed that 60.63% of isolates in this group showed in vitro sensitivity to piperacillin–tazobactam combination closely followed by amikacin with 56.69% overall sensitivity. The overall sensitivity to levofloxacin and meropenem was 41.73% and 40.12% respectively (Table 4).
Table 4.
Overall sensitivity of individual antibiotic to the total culture isolates flora (monomicrobial + polymicrobial) in pediatric age
| 0rganism (Total counts) | Amk | Gen | Pit | Azt | Ctr | Ctz | Cfs | cfx | Cpm | Cts | mrp | imp | Cld | Col | Lev | Cot | Amc | Tg | Tb | DOX | Cef | Azm | V | HG | HS | Mn |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pseudomonas (37* + 11** = 48) | 27 | 25 | 36 | 26 | – | 17 | – | 1 | 16 | – | 21 | 4 | – | 14 | 19 | – | – | 1 | – | – | – | – | – | – | – | |
| Proteus mirabilis (17* + 5** = 22) | 11 | 1 | 18 | – | 11 | 1 | 12 | 13 | – | 2 | 13 | – | – | – | 11 | 6 | 1 | 1 | – | – | – | – | – | – | – | – |
| Proteus vulgaris (4*) | 4 | – | 4 | – | 2 | – | 1 | 2 | – | 2 | 3 | 1 | – | – | 2 | – | 2 | – | – | – | – | – | – | – | – | – |
| MRSA (10* + 2** = 12) | 6 | – | – | – | – | – | – | – | – | – | – | – | 4 | – | 2 | 5 | – | – | – | – | – | 3 | 11 | – | – | – |
| MSSA (7* + 3** = 10) | 9 | – | – | – | – | – | – | – | – | – | – | – | 8 | – | 5 | 5 | 1 | – | – | – | 10 | 7 | 1 | – | – | – |
| E.coli (4* + 6** = 10) | 7 | – | 9 | – | 5 | – | 5 | 2 | 2 | 2 | 6 | – | – | – | 3 | 4 | 1 | – | – | – | – | – | – | – | – | – |
| Enterococci fecalis (4* + 4** = 8) | – | – | – | – | – | – | – | – | – | – | – | – | 2 | – | 4 | – | – | – | – | 7 | – | 1 | 8 | 8 | 6 | – |
| Citrobacter koseri (4* + 3** = 7) | 4 | 2 | 6 | – | 4 | – | 5 | 1 | – | – | 5 | – | – | – | 2 | 1 | – | 1 | – | – | – | – | – | – | – | 1 |
| Klebsiella pneumonia (4* + 1** = 5) | 3 | 1 | 3 | – | 2 | – | 2 | 2 | – | 1 | 3 | – | – | 1 | 4 | 3 | 1 | 1 | – | – | – | – | – | – | – | – |
| Klebsiella oxytoca (1**) | 1 | – | 1 | – | – | – | 1 | – | – | – | – | 1 | – | – | 1 | – | – | – | – | – | – | – | – | – | – | – |
| Total flora (127) | 72 | 29 | 77 | 26 | 24 | 18 | 26 | 21 | 18 | 7 | 51 | 6 | 14 | 15 | 53 | 24 | 6 | 3 | 1 | 7 | 10 | 11 | 20 | 8 | 6 | 1 |
| % (sensitivity) | 56.69 | 22.83 | 60.63 | 20.47 | 18.90 | 14.17 | 20.47 | 16.53 | 14.17 | 5.51 | 40.12 | 4.27 | 11.02 | 11.81 | 41.73 | 18.90 | 4.72 | 2.36 | 0.78 | 5.51 | 7.87 | 8.66 | 15.74 | 6.29 | 4.72 | 0.78 |
*Monomicrobial culture isolate, **As a part of polymicrobial culture isolate
It needs to be noted that Methicillin Sensitive Staphylococcus Aureus (MSSA) was present only in the pediatric group and constituted 7.87% of isolates.
Rest of the isolates and their sensitivity pattern are mentioned in Table 3.
Adult Population
A total of 9 species of micro organisms were isolated from these patients with a total of 103 isolates, comprising of 81 monomicrobials and 22 polymicrobials.
Pseudomonas species were present in 53 (51.46%) of the isolates making it the most common isolate in the adult group as well (Table 2).Here again the strains showed maximum in vitro sensitivity to piperacillin–tazobactam combination (79.24%). It is noteworthy that pseudomonas species showed poor sensitivity to cephalosporin group of antibiotics in general (Table 5).
Table 5.
Antibiotics sensitivities of individual microbial flora in older population
| 0rganism | Amk | Gen | Pit | Azt | Ctr | Ctz | Cfs | cfx | Cpm | Cts | mrp | imp | Cld | Col | Lev | Cot | Amc | Tg | Tb | DOX | Cef | Azm | V | HG | HS | Mn |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (1) Pseudomonas Total = 53 | 36 | 33 | 42 | 33 | – | 19 | – | – | 13 | – | 31 | 5 | – | 12 | 25 | – | – | – | – | – | – | – | – | – | – | – |
| Percentage (%) | 67.92 | 62.26 | 79.24 | 62.26 | – | 35.85 | – | – | 24.53 | – | 58.49 | 9.43 | – | 22.64 | 47.17 | – | – | – | – | – | – | – | – | – | – | – |
| (2) Citrobacter sp. Total = 16 | 10 | 1 | 14 | – | 10 | – | 11 | 10 | – | 2 | 7 | 2 | – | 1 | 6 | 6 | 4 | – | – | – | – | – | – | – | – | 1 |
| Percentage (%) | 62.5 | 6.25 | 87.5 | – | 62.5 | – | 68.75 | 62.5 | – | 12.5 | 43.75 | 12.5 | – | 6.25 | 37.5 | 37.5 | 25 | – | – | – | – | – | – | – | – | 6.25 |
| (3) Proteus sp. Total = 10 | 6 | 1 | 7 | – | 7 | – | 2 | 6 | – | 3 | 4 | 1 | – | – | 5 | 5 | 2 | – | – | – | – | – | – | – | – | – |
| Percentage (%) | 60 | 10 | 70 | – | 70 | – | 20 | 60 | – | 30 | 40 | 10 | – | – | 50 | 50 | 20 | – | – | – | – | – | – | – | – | – |
| (4) Klebsiella sp. Total = 8 | 5 | – | 6 | – | 4 | – | 3 | 1 | – | 3 | 4 | – | – | 1 | 2 | 2 | – | 1 | – | – | – | – | – | – | – | 1 |
| Percentage (%) | 62.5 | – | 75 | – | 50 | – | 37.5 | 12.5 | – | 37.5 | 50 | – | – | 12.5 | 25 | 25 | – | 12.5 | – | – | – | – | – | – | – | 12.5 |
| (5) MRSA Total = 7 | 6 | – | – | – | – | – | – | – | – | – | – | – | 4 | – | 1 | 4 | – | – | – | – | – | – | 7 | – | – | – |
| Percentage (%) | 85.71 | – | – | – | – | – | – | – | – | – | – | – | 57.14 | – | 14.28 | 57.14 | – | – | – | – | – | – | 100 | – | – | – |
| (6) E.coli Total = 3 | 2 | – | 2 | – | 1 | – | 1 | 1 | – | 2 | 2 | – | – | – | 2 | 1 | – | – | – | – | – | – | – | – | – | – |
| Percentage (%) | 66.66 | – | 66.66 | – | 33.33 | – | 33.33 | 33.33 | – | 66.66 | 66.66 | – | – | – | 66.66 | 33.33 | – | – | – | – | – | – | – | – | – | – |
| (7) Enterococci sp. Total = 4 | – | – | – | – | – | – | – | – | – | – | – | – | 1 | – | 2 | 1 | – | – | – | 2 | 1 | 3 | 3 | 2 | – | |
| Percentage (%) | – | – | – | – | – | – | – | – | – | – | – | – | 25 | – | 50 | 25 | – | – | – | 50 | 25 | 75 | 75 | 50 | – | |
| (8) Acinetobacter Total = 1 | 1 | – | 1 | – | 1 | – | 1 | – | – | – | 1 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Percentage (%) | 100 | – | 100 | – | 100 | – | 100 | – | – | – | 100 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| (9) P.rettgeri Total = 1 | – | – | 1 | – | – | – | – | – | – | 1 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Percentage (%) | – | – | 100 | – | – | – | – | – | – | 100 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
Unlike the pediatric age group, it was citrobacter species which were the second most common isolate (15.53%) (Table2). These strains too showed best in vitro sensitivity to piperacillin–tazobactam combination (87.5% of isolates) (Table 5). In contrast to pseudomonas species, citrobacter species showed a fair response to cephalosporins as well (62.5% to 68.75%). Proteus species comprised 9.71% of isolates (Table 2) and there was 70% sensitivity to both piperacillin–tazobactam combination as well as to ceftriaxone (Table 5).
Overall in this group also, it was piperacillin–tazobactam combination which was observed to be most effective with an overall sensitivity of 70.87%. Importantly,amikacin also showed a fair overall sensitivity of 64.08% in this group (Table 6).
Table 6.
Overall sensitivity of individual antibiotic to the total culture isolates flora (monomicrobial + polymicrobial) in older age
| 0rganism (Total counts) | Amk | Gen | Pit | Azt | Ctr | Ctz | Cfs | cfx | Cpm | Cts | mrp | imp | Cld | Col | Lev | Cot | Amc | Tg | Tb | DOX | Cef | Azm | V | HG | HS | Mn |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pseudomnas (44* + 9** = 53) | 36 | 33 | 42 | 33 | – | 19 | – | – | 13 | – | 31 | 5 | – | 12 | 25 | – | – | – | – | – | – | – | – | – | – | - |
| Citrobacter koseri (9* + 3** = 12) | 7 | 1 | 10 | – | 7 | 1 | 8 | 7 | – | 1 | 3 | 2 | – | 1 | 3 | 3 | 2 | – | – | – | – | – | – | – | – | 1 |
| Citrobacter freundii (4* + 0 = 4) | 3 | – | 4 | – | 3 | – | 3 | 3 | – | 1 | 4 | – | – | – | 3 | 3 | 2 | – | – | – | – | – | – | – | – | – |
| Proteus mirabilis (7* + 2** = 9) | 5 | 1 | 7 | – | 7 | – | 2 | 6 | – | 3 | 3 | 1 | – | – | 4 | 4 | 2 | – | – | – | – | – | – | – | – | – |
| Proteus vulgaris (1* + 0 = 1) | 1 | – | – | – | – | – | – | – | – | – | 1 | – | – | – | 1 | 1 | – | – | – | – | – | – | – | – | – | – |
| MRSA (5* + 2** = 7) | 6 | – | – | – | – | – | – | – | – | – | – | – | 4 | – | 1 | 4 | – | – | – | – | – | – | 7 | – | – | – |
| Klebsiella pneumoni (3* + 3** = 6) | 5 | – | 5 | – | 4 | – | 3 | 1 | – | 2 | 4 | – | – | – | 2 | 2 | – | – | – | – | – | – | – | – | – | – |
| Klebsiella oxytoca (1* + 1* = 2) | – | – | 1 | – | – | – | – | – | – | 1 | – | – | – | 1 | – | – | – | 1 | – | – | – | – | – | – | – | 1 |
| Escherchia coli (3*) | 2 | – | 2 | – | 1 | – | 1 | 1 | – | 2 | 2 | – | – | – | 2 | 1 | – | – | – | – | – | – | – | – | – | – |
| Enterococci fecalis (2* + 2** = 4) | – | – | – | – | – | – | – | – | – | – | – | – | 1 | – | 2 | 1 | – | – | – | 2 | 1 | 3 | 3 | 2 | – | |
| Acinetobacter (1*) | 1 | – | 1 | – | 1 | – | 1 | – | – | – | 1 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Providencia rettgeri (1*) | – | – | 1 | – | – | – | – | – | – | 1 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Total(103) | 66 | 35 | 73 | 33 | 23 | 20 | 18 | 18 | 13 | 11 | 49 | 8 | 5 | 14 | 43 | 19 | 6 | 1 | – | 2 | – | 1 | 10 | 3 | 2 | 2 |
| %(sensitivity) | 64.08 | 33.98 | 70.87 | 32.03 | 22.33 | 19.42 | 17.48 | 17.48 | 12.62 | 10.68 | 47.57 | 7.76 | 4.85 | 13.59 | 41.75 | 18.44 | 5.83 | 0.97 | – | 1.94 | 0.97 | 9.71 | 2.91 | 1.94 | 1.94 |
*Monomicrobial culture isolate, **As a part of polymicrobial culture isolate
Discussion
Clinical Profile
A total of 193 patients participated in the present study. These were divided into pediatric and adult groups based on their age.
The male to female ratio in the pediatric population was 1:0.65 while that in the adult population was 1:1.12. As far as gender pre-disposition in COM is concerned, there are studies favouring male predominance [8, 10–15] and at the same time there are others showing a female predominance [16, 17]. This lack of gender parity in the samples indicates that it is not the disease per se, which has a gender predisposition but it is the study cohort which is likely to account for this variability. At the same time, it is worth noting that in the present study males outnumbered females in pediatric age group whereas the scenario is reversed in the adult group. Although this difference falls just below the level of statistical significance with the 95% confidence limit (p = 0.06), it still merits consideration. The authors are of the opinion that it is due to the preferential position which a male child has in the population under study. Unfortunately, this precludes a female child from an early access to treatment. It is usually at the marriageable age or after that they are brought to medical attention.
Bacteriology
There was significant difference in the incidence of pseudomonas isolates in pediatric (37.80%) and adult (51.46%) population.
Studies have reported pseudomonas to be a robust biofilm producer. Within the biofilms, a proportion of the bacterial colonies maintain a low metabolic rate than their planktonic forms. This serves as a defense mechanism against antibiotics. The biofilms also offer protection from phagocytosis and host immune response [18]. Furthermore, pseudomonas infections are mostly seen when there is a discontinuity of normal skin or when normal flora is replaced by this organism due to constant use of topical antibiotics. Hence, longer the duration of disease, more would be the tissue damage and greater would be the incidence of pseudomonas infection. This explains the difference in the incidence of pseudomonas isolates in pediatric and adult population.
Overall, pseudomonas was found to be the most common organism which is in agreement with a host of other studies.[8, 9, 14, 17, 19–23]. In this regard two important differences are being noted in studies from different regions. Firstly, in studies showing pseudomonas as the most common organism, its percentage share in the total isolates shows wide variation. It varied from 25.4 [24] to 45.24% [22]. Secondly, not every study showed pseudomonas to be the most common isolate. In fact, a number of studies found staphylococcus aureus as the most common isolate [16, 25, 26]. Here also, the proportion of staphylococcus varied widely among different regions ranging from 31.8 [26] to 50% [25]. Furthermore, an Ethiopian study [13] found Proteus species (37.7%) as the most common isolate further contributing to the variability.
Another important difference noted between pediatric and adult age group was the exclusive presence of methicillin sensitive staphylococcus aureus in the pediatric population. This was indeed highly significant (p = 0.03).
There are also other differences being noted between adult and pediatric population for instance, the presence of Acinetobacter and Providencia rettgeri exclusively in adult population. However, this and other such differences would be deemed invalid for statistical evaluation owing to the limited number of isolates of these species.
The Sensitivity Pattern
In the present study, the most effective of the drug regimen against pseudomonas was piperacillin–tazobactam combination. It had a sensitivity of about 75% in the pediatric group and about 80% in the adult group. This is comparable with the existing studies [9, 15, 23, 26]. However, antibiotic sensitivity of pseudomonas varies in different regions. In a middle eastern study [24], ciprofloxacin was found to be most effective against pseudomonas (93.9%). In yet another study [27], ceftazidime was the most effective drug against pseudomonas. There is also variation in drug sensitivity over time. A few older Indian studies show excellent sensitivity of aminoglycosides [8]. However, from the present study and a few other recent works [24], the aminoglycosides efficacy against pseudomonas is showing a declining trend.This again goes to show the changing sensitivity patterns and the emerging drug resistance.
Overall, the gram negative bacterial isolates which were the predominant microorganisms showed fair degree of sensitivity to Piperacillin–Tazobactam combination followed by Amikacin.
Funding
Not funded by any agency.
Compliance with Ethical Standards
Conflicts of interest
The authors declare that they have no conflict of interest.
Ethical Approval
All procedures performed were in accordance with the ethical standards of institutional ethics committee and with the 1964 Helsinki declaration and its later amendments or comparable standards.
Informed Consent
All participants were adequately informed about the procedure and an informed written consent was taken. In case of children less than 18 years, consent was taken from their parents or guardians.
Footnotes
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