|Year : 2014 | Volume
| Issue : 4 | Page : 155-159
Bacterial isolate and antibacterial resistance pattern of ear infection among patients attending at Hawassa university referral Hospital, Hawassa, Ethiopia
Mesfin Worku1, Muluken Bekele2
1 Hawassa University, Medicine and Health Science, Hawassa, Ethiopia
2 ENT Unit, School of Medicine, Medicine and Health Science, Hawassa, Ethiopia
|Date of Web Publication||13-Dec-2014|
Department of Medical Laboratory Sciences, Hawassa University Health Science, Hawassa
Source of Support: None, Conflict of Interest: None
Background: Ear infection is highly prevalent worldwide. In the older child, long-standing Chronic Supparative Ottitis Media can result in a severe conductive hearing loss with significant drawbacks in learning, communication, and social adjustment. It is associated with hearing impairment, death, and severe disability due to central nervous system involvement in developing countries. Objective: To determine the bacteriological profile and antibacterial resistance of ear infection from patients seen at Ear Nose and Throat clinic of Hawassa University Referral Hospital. Materials and Methods: A cross-sectional study was conducted at clinic of Hawassa University Referal Hospital. Result: A total 117 study subjects included in this study from June 2013 to October 2013. Among these, 57 (48.7%) were male and 53 (45.3%) were children. Bacteria identified from positive ear swabs were: Staphylococcus aureus 24 (20.5%), Pseudomonas aeroginosa 17 (14.5%), Klebsiella species 10 (8.5%), Proteus species 7 (6.0%), Entrobacter species 4 (3.4%), Escherchia coli 3 (2.6%), Citrobacter species 2 (1.7%), and Providentia species 2 (1.7%). The overall sensitivity and resistance profile of antibacterial agent, Amikacin (90.0%) and Gentamycin (89.1) showed high level of antibacterial effect on all identified bacterial species. On other hand, all isolates were highly resistance to ampicilin (87.5%), oxacillin (84.0%), ceftriaxone (82.8%), cephalotin (81.4%), and penicillin G (73.8%). Conclusion: Most of the isolates were resistant to commonly prescribed drug in the area. However, Amikacin and Gentamycin were highly active against the isolated organism, whereas Ciprofloxacilin was moderately active. Therefore, culture and susceptibility test is vital for appropriate management of ear infection in study area.
Keywords: Antibiotic susceptibility pattern, Ear infection, Ethiopia
|How to cite this article:|
Worku M, Bekele M. Bacterial isolate and antibacterial resistance pattern of ear infection among patients attending at Hawassa university referral Hospital, Hawassa, Ethiopia. Indian J Otol 2014;20:155-9
|How to cite this URL:|
Worku M, Bekele M. Bacterial isolate and antibacterial resistance pattern of ear infection among patients attending at Hawassa university referral Hospital, Hawassa, Ethiopia. Indian J Otol [serial online] 2014 [cited 2017 Nov 19];20:155-9. Available from: http://www.indianjotol.org/text.asp?2014/20/4/155/146929
| Introduction|| |
Otitis media is an inflammation of the middle ear and mastoid process which could be acute purulent otitis media and chronic suppurative otitis media.  Acute otitis media (AOM) is the most frequent bacterial infection and the most frequent cause of antibiotic use in children. ,,,,,, Chronic suppurative otitis media (CSOM) is a chronic inflammation of the middle ear and the mastoid process with perforated tympanic membrane and ear discharge persisting for at least two weeks. ,,
About 65-300 million people suffered from otitis media globally; of these, about 60% experience significant hearing impairment. , The socio-economic impact of this disease is great with a cost exceeding 5 billion dollars annually. ,,
Even if the causative agents varies based on Geography ,, , the isolates such as Streptococcus pneumoniae, Staphylococcus aureus, Hemophilus influenzae, and Moraxella More Details catarrhalis from an acute infection, ,, whereas Pseudomonas aeruginosa, Staphylococcus aureus, Proteus mirabilis, Klebsiella pneumonia, and Escherichia More Details coli are common in chronic otitis media. ,
Moreover, antimicrobial resistance profile of bacteria varies among population because of difference in geography, local antimicrobial prescribing practices, and prevalence of resistant bacterial strains. ,
Very few numbers of studies on bacterial profile and antimicrobial sensitivity tests were done in Ethiopia. Most of these studies have focused on children with little or no report on adult patients. To our knowledge, there is no information about prevalence and antimicrobial susceptibility test on both children and adult in Hawassa area. Therefore, this study aimed to determine the bacterial profile and the antimicrobial susceptibility test in Hawassa University Referral Hospital.
| Materials and Methods|| |
Hawassa town is the capital city of Southern Nations, Nationalities, and Peoples Region (SNNPR) and it is located 275 km from capital city of Ethiopia, Addis Ababa. The altitude of the town is 1,697 km above sea level with mean annual temperature and rainfall of 20.9°C and 997.6 mm, respectively. Hawassa University referral Hospital (HURH) is a tertiary health care hospital serving the population of south nations and nationalities (SNNPR) and the neighboring Oromiya region in southern Ethiopia. There about 12 million populations are getting service by the hospital.
A total 117 study subjects were included in present study from June 2013 to October 2013. Among these, 57 (48.7%) were male and 60 (51.3%) were female. In addition, 53 (45.3%) of the total study subjects were children and the rest were adult.
A cross-sectional study was conducted from June 2013 to October 2013 at ear, nose, and throat (ENT) clinic of Hawassa University Referal Hospital. Sample size is determined using a single population proportion formula by considering a 95% confidence interval that is 5% level of significance and assuming the prevalence of otitis media to be 91.7% as indicated by the study conducted in Dessie Regional Health Research Laboratory, Northern Ethiopia.  Therefore, a total of 117 subjects were selected based on systematic random sampling method by recruiting every fifth case of ear infection to our study.
Sample collection and processing
Ear swab samples were collected using a sterile swab stick from patients with various ear infections at Hawassa University Referral Hospital ENT clinic from June 2013 to October 2013. The ear swab samples were sent to the teaching laboratory of Hawassa University Referral Hospital for processing immediately by Amies transport media (Oxoid Company). Upon receipt of the samples, they were inoculated on MacConkey and Blood agar (Oxoid Company) plates and incubated at 37 o C aerobically and also inoculated on Chocolate agar (Oxoid Company) plates and incubated in a 5-10% CO 2 jar at 37 o C. The swab was then gram stained on a slide and examined. Discrete colonies of isolates were sub-cultured on Nutrient agar (Oxoid Company) to obtain pure culture for characterization.
Characterization of isolated bacteria
Bacteria isolates were characterized based on colonial appearance, gram reaction, cultural characteristics, and biochemical tests as described by Cheesbrough. Biochemical tests carried out include; catalase, urease, coagulase, oxidase, carbohydrate fermentation, motility, gas production, citrate utilization, and indole test. 
Antibacterial susceptibility testing
Antibacterial susceptibility testing was performed for all isolates according to the criteria of the National Committee for clinical Laboratory Standard (NCCLs) by disc diffusion method. From a pure culture 3-5 selected colonies of bacteria were taken and transferred to a tube containing 5 ml nutrient broth and mixed gently until a homogenous suspension will be formed and incubated at 37°C until the turbidity of the suspension will become adjusted to a McFarnald 0.5. A sterile cotton swab was used and the excess suspension was removed by gentile rotation of the swab against the surface of tube. The swab was then used to distribute the bacteria evenly over the entire surface of Mullen-Hinton agar. The inoculated plates were left at room temperature to dry for 3-5 minutes and a set of antibiotic discs such as Amoxacilin (25 μg), Ampicilin (10 μg), Vancomycin (30 μg), Nalidixic acid (30 μg), Ciprofloxacilin (5 μg), Gentamycin (10 μg), Amikacin (30 μg), Ceftriaxone, Cephalothin (30 μg), Penicilin G (10 μg), Oxacilin (1 μg), Augumentin (30 μg), Chloroamphenicol, and Tetracycline (30 μg) were dispensed on the surface of the inoculated Muller-Hinton plate. The inoculated plate then incubated at 37 o C for 24-48 hrs. 
Data entry and analysis was performed using Statistical Package for the Social Sciences (SPSS) version 16.0 software. Comparisons ware done using Chi-square test. A P value of <0.05 was considered as indicative of statistically significant difference.
The Quality of the study was assured by training the data collector, preparing, and using standard operational procedures for laboratory investigation and media preparation.  Structured questionnaire was tested using pretest before conducting the study. Sample collection and processing was carried out using aseptic techniques. The sample was labeled properly. The performance and sterility test of prepared media will be determined by incubating at 37°C and inoculating with control organisms, respectively.
This study was approved by the Hawassa University College of Medicine and Health Science institutional review board. Written informed consent was obtained from all adult patients. Written information sheet will be obtained from parents/guardians for the children who participated in this study. All participants of this study free of charge for laboratory diagnosis but individual with ear infection was referred to their physicians for treatment.
| Results|| |
A total 117 study subjects are included in this study from June 2013 to October 2013. Among these, 57 (48.7%) were male and 53 (45.3%) were children [Table 1]. According to clinical diagnosis, majority were ottits media (93.2%). From 117 ear swab cultures, 61 (52.1%) were bacterial cultures positive. There was almost equal distribution of bacterial species between acute ear infection 33 (28.2%) and chronic ear infection 36 (30.8%) [Table 2]. From culture positive ear discharges, 110 (94%) had single isolates and only 7 had mixed ones. The majority of the species were gram-negative bacteria which accounted for 93 (79.5%). The type of bacteria identified from positive ear swabs were: Staphylococcus aureus 24 (20.5%), Pseudomonas aeroginosa 17 (14.5%), Klebsiella species 10 (8.5%), Proteus species 7 (6.0%), Entrobacter species 4 (3.4%), Escherchia coli 3 (2.6%), Citrobacter species 2 (1.7%), and Providentia species 2 (1.7%). S. aureus was the most frequent bacterial species in both disease status with 10 (16.4%) and 14 (25.0%) frequencies in acute and chronic ear infection patients, respectively [Table 2].
|Table 1: Age - and sex - specific distribution of bacterial species among study subjects at Hawassa University Referral Hospital, Hawassa, Ethiopia|
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|Table 2: Frequency of bacterial species isolated from study subjects at Hawassa University Referral Hospital, Hawassa, Ethiopia|
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A total of 14 commonly prescribed drugs in the study area were tested against the identified bacterial species for antibacterial resistance pattern. Based on overall sensitivity and resistance profile of antibacterial agent, Amikacin (90.0%) and Gentamycin (89.1) showed high level of antibacterial effect on all identified bacterial species. On other hand, all identified bacterial species were highly resistance to Ampcilin (87.5%), Oxacillin (84.0%), Ceftriaxone (82.8%), Cephalotin (81.4%), and Penicillin G (73.8%) [Table 3].
|Table 3: Overall sensitivity and resistance profile of antimicrobial agents tested for bacterial species of ear infections at Hawassa University Referral Hospital, Hawassa, Ethiopia|
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Staphylococcus aureus showed high level of susceptibility to Vancomycin (94.7%), Amikacin (88.9%), Augumentin (83.3%), and Gentamycin (80.0%). However, this organism was highly resistance to Ceftriaxone (84.2%), Oxacillin (61.1%), Penicillin (59.0%), and Cephalotin (58.8%). Pseudomonas aeruginosa also showed high susceptibility to Amikacin and Gentamycin with sensitivity of 94.1%. On the other hand, it was resistant to Penicillin (100.0%) and Ceftriaxone (94.1%), Nalidixic acid (70.6%). Klebsiella species and Proteus species indicated high level susceptibility (90-100%) to Amikacin and Gentamycin, whereas resistant (70-100%) to Ampcilin, Ceftriaxone, and Cephalotin.
As it is depicted in [Table 4], Antibiogram showed that almost all isolates (98.6%) were resistant to one and more drugs and multidrug resistant against two to more drugs was 97.1% as well.
|Table 4: Antibiogram of bacterial species identified from study subject of ear infection at Hawassa University Referral Hospital, Hawassa, Ethiopia|
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| Discussion|| |
Ear infection is the problem of all age-group in the study area. Flow of patient with ear problem is rising from time to time. The burden of the illness is higher (55.1%) in children than adult cases. This in agreement with study conducted in Ethiopia , and in Benin.  This is due to the fact that younger children are more prone to otitis media related to their immune status, the shorter and horizontal nature of Eustachian tube More Detailss, frequent exposure to upper respiratory tract infections and malnutrition. ,
The current study showed that gram-negative bacteria are more frequent (79.5%) than gram-positive bacteria. Similarly, study from Dessie, Ethiopia  showed the comparable result the current result. Staphylococcus aureus was the most predominant isolate with an occurrence of 24 (20.5%), followed by Pseudomonas aeroginosa 17 (14.5%), Klebsiella species 10 (8.5%), Proteus species 7 (6.0%), Entrobacter species 4 (3.4%), Escherchia coli 3 (2.6%), Citrobacter species 2 (1.7%), and the least predominate was Providentia species 2 (1.7%). The occurrence of Staphylococcus aureus of current study was inconsistent with previous study conducted in Ethiopia. , However, it was supported by study conducted in Benin by Akinjogunla et al. Probable explanation to this difference in isolation rate might be related to the effect of climate and geographical variation. Bacterial colonization of otitis media increases as temperatures rise which in turn increases the isolation rate of bacteria. 
Currently, the flow of patients to ENT clinic and the prescription for ear infection are rapidly increasing. The knowledge of the bacteriology of an ear infection and the laboratory susceptibility testing of micro-organism implicated could make drug selection in antimicrobial chemotherapy more rational. Therefore, this study tried to address antibacterial susceptibility and resistance pattern of the commonly isolated bacteria from ear infection. Base on the [Table 3], the overall sensitivity and resistance profile of antibacterial agent was, Amikacin (90.0%) and Gentamycin (89.1) showed high level of antibacterial effect on all identified bacterial species and Ciprofloxacilin (60.6%) had moderate antibacterial effect. On other hand, all identified bacterial species were highly resistance to Ampcilin (87.5%), Amoxacillin (66.7%), Ceftriaxone (82.8%), Cephalotin (81.4%), and Penicillin G (73.8%). These results were almost comparable with previous study done in Dessie, Ethiopia. , However, the susceptibility of the isolates to ciprofloxacilin was showed discrepancy with the present study. The possible explanation for this variation could be the emerging of new resistance strains from time to time due to various reasons like irrational use drug.
This study revealed that Staphylococcus aureus showed high level of susceptibility to Vancomycin (94.7%), Amikacin (88.9%), Augumentin (83.3%), and Gentamycin (80.0%). However, this organism was highly resistance to Ceftriaxone (84.2%), Oxacillin (61.1%), Penicillin (59.0%), and Cephalotin (58.8%). The antimicrobial pattern of Gentamycin, Tetracyclin, and Cephalotin on Staphylococcus aureus in agreement with study conducted in Dessie, Ethiopia.  Whereas chloroamphenicol, Ciprofloxacilin, Amoxacilin, and Ceftriaxone were inconsistent with present study. Pseudomonas aeruginosa also showed high susceptibility to Amikacin and Gentamycin with sensitivity of 94.1%. On the other hand, it was resistant to Penicillin (100.0%), Ceftriaxone (94.1%), and Nalidixic acid (70.6%). Similar study done by Abera in Ethiopia  has different date with this study. The probable reasons for this variation could be attributed to antimicrobial resistance profile of bacteria varies among population because of difference in geography, local antimicrobial prescribing practices and prevalence of resistant bacterial strains. ,
Concerning to antibiogram, present study was indicated that almost all isolates (98.6%) were resistant to one and more drugs. Moreover, multidrug resistant isolates against two and more drugs was 97.1% as well. There was one isolate that was sensitive to all antibiotics tested. This high rate of multidrug resistance could be attributed to misuse of drugs. 
| Conclusion|| |
In conclusion, the current study stated that Staphylococcus aureus, Pseudomonas aeruginosa, and enterobacteriacea were commonly identified etiology of ear infection both in children and adult. Most of these isolate were resistant to commonly prescribed drug in the study area. However, some of the drug like Amikacin and Gentamycin were highly active against to the isolated organism, whereas Ciprofloxacilin was moderately active. Therefore, culture and susceptibility test is vital for appropriate management of ear infection in study area.
| Acknowledgments|| |
We would like to thank Hawassa University for financial support. Our gratitude also goes to data collectors such as Sr Mekdes Tadese, Sr Yeromnesh Kebede, Gloria Gezahegn and Mss Yeshareg Behailu for their efficient and valuable effort for this fruitful work.
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[Table 1], [Table 2], [Table 3], [Table 4]
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