Ear infections are extremely common and widespread otological disorders in children and adults. Accordingly, it is critical to identify the etiological factors and determine their antimicrobial susceptibility to achieve successful clinical outcomes. Ear swab samples were collected from patients aged 10-69 years at the Al-Sadar Teaching Hospital in Al-Amara city and cultured using the standard microbiological methods. The VITEK 2-compact system was used to analyze the bacterial isolates. A total of 100 samples were obtained; ear infection was slightly elevated in men (58%), but this was not significant. A significantly higher incidence of ear infection was observed in the patients aged 10–19 years (P≤ 0.05). Of the 100 examined ear swab samples, 76 yielded positive culture results, and of these, 61 were axenic and 15 were mixed. Among the 91 retrieved bacterial isolates, Pseudomonas aeruginosa (24/91, 26.3%) and Staphylococcus aureus (21/91, 23%) were the common causative agents of ear infection, while Haemophilus influenzae (2/91, 2.19%) and Staphylococcus hominis (1/91, 1.09%) were less common. Most bacterial isolates showed high sensitivity to imipenem and amikacin (87.9% and 79.1%, respectively; P≤ 0.01), followed by ciprofloxacin and gentamicin (67% and 60.4%, respectively; P≤ 0.05), and low sensitivity to amoxicillin/clavulanic acid and ampicillin (15.3% and 6.6%, respectively). Multidrug resistance was observed in most of the isolates.
Ear infection, Bacteria, Antibiotics, Al-Amara, Iraq
Ear infection results in ear inflammation, with ear discharge being one of the most prevalent signs.1 Globally, ear infections affect approximately 330 million individuals; of these, 60% have substantial hearing loss.2 Ear infections may be acute or chronic purulent,3 occurring in the external, middle, or internal parts of the ear.4 Inflammation of the middle ear, known as otitis media, is a common type of ear infection.5 As the eustachian canal is shorter and more horizontal in children than that in adults, children have a higher frequency of ear infections than adults.6
Although the etiologies vary based on the geographical areas,7,8 Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenza are more commonly isolated from acute ear infections,9 whereas Pseudomonas aeruginosa, S. aureus, Proteus mirabilis, Klebsiella pneumonia, and Escherichia coli are more common in chronic infections.5 The development and spread of bacterial resistance have become a serious concern for global health owing to the increasing and irrational use of broad-spectrum antibiotics.3,10 Complications, such as meningitis and brain abscess, may arise as a result of the increased prevalence of antibiotic-resistant bacteria in ear infections.7 Additionally, middle ear tumors, post-aural edema, and aural sinuses can result from ear infections.8
Recently, ear infections have been reported in both sexes and different age groups in Al-Amara city, Maysan, Iraq. This study was aimed at identifying the bacterial species associated with the reported cases of ear infections and determining their sensitivity to antibiotics.
Study design and Ethical approval
This descriptive study was conducted between February and May 2022 at the College of Pharmacy, University of Misan, Al-Amara City, Misan Governorate, Iraq. The study was approved by the ethics committee of the College of Pharmacy, University of Misan, and written informed consent was obtained from all the volunteers or their parents for the collection of their data for this study. Data about the age and sex of the participants were collected using questionnaires.
Sample collection and participants
One hundred ear swab samples were collected from patients aged 10-69 years who visited the ear, nose, and throat clinic at the Al-Sader Teaching Hospital in Al-Amara, Iraq. Ear discharge samples were collected using sterile cotton swabs (Hemidia, Netherlands), placed in Amies transport media (Hemidia, Netherlands), and transported to the microbiology laboratory of the College of Pharmacy within 1 h.
Isolation and identification of bacteria
Samples plated onto blood and MacConkey agar plates (Oxoid, UK) were cultured aerobically, whereas those plated onto chocolate agar were incubated in a candle jar at 37°C for 24 hours.11 Bacterial colonies were initially identified based on Gram staining, colony morphology, and hemolysis type. Final identification was performed using the Vitek 2 system (Gram Negative, Gram Positive, and Neisseria-Haemophilus identification cards (GP, GN, and NH ID cards, Biomereiux, France)).
Antibiotic sensitivity testing
The standard disk diffusion method was used to test the antibiotic sensitivity, and the results were interpreted in accordance to the Clinical Laboratory Standard Institute guidelines.12 The tested antibiotics were ampicillin (10 µg), amikacin (30 µg), amoxicillin/clavulanic acid (30 µg), ceftazidine (30 µg), ceftriaxone (30 µg), co-trimaxazole (25 µg), ciprofloxacin (5 µg), gentamicin (10 µg), imipenem (30 µg), and tetracycline (30 µg) (Titan, Biotech., India).
Data were analyzed using the chi-square test in the Statistical Package for Social Science Software version 19. P-value ≤ 0.05 was considered significant.
A significant difference was observed in the incidence of ear infections between the patients aged 10–19 years (61%; P ≤ 0.05) compared to those aged 20 or more than years old, with no significant difference between the men and women (58% and 42%, respectively; Table 1). A total of 100 ear swab samples were tested; bacterial growth was observed in 76 samples only compared to 24 with no growth (P ≤ 0.01). Only 61 samples yielded axenic, not mixed, cultures (P ≤ 0.05; Table 2). Among the 91 bacterial isolates, P. aeruginosa and S. aureus were the most commonly observed bacterial strains (24 and 21, respectively), followed by P. mirabilis, Staphylococcus epidermidis, K. pneumonia, E. coli, S. pneumonia, Proteus vulgaris, H. influenza, and Staphylococcus hominis (13, 10, 7, 5, 4, 4, 2, and 1 case(s), respectively).
Sex and age distribution among patients with ear infection.
|Sex||Percentage||Age group (years)||Percentage|
*: P ≤ 0.05.
Bacterial culture isolated from ear swab samples.
*: P ≤ 0.05.
Antibiotic sensitivity testing for bacterial ear infections (n=91) showed high sensitivity to imipenem and amikacin (87.9% and 79.1%, respectively; P ≤ 0.01), followed by ciprofloxacin and gentamicin (67% and 60.4%, respectively; P ≤ 0.05), and low sensitivity to amoxicillin/clavulanic acid and ampicillin (16.4% and 6.6%, respectively; Table 3).
Antibiotic susceptibility profile of bacterial isolates from patients with ear infection.
|*N||Sensitivity pattern of antibiotics n(%)|
*N: Number of isolates, **: P ≤ 0.01, ***: P ≤ 0.05
IMP: Imipenem, AK: Amikacin, CN: Gentamicin, CIP: Ciprofloxacin, TE: Tetracycline, CTR: Ceftriaxone, CFX: Ceftazidine, SXT: Co-trimaxazole, AMC: Amoxicillin/clavulanic acid, AMP: Ampicillin
The present study indicated that patients aged 10-19 years had the highest incidence of ear infections, which is consistent with previous studies which reported that most ear infections occurred in people less than 20 years old.13-16 The short, broad, and straight structure of the eustachian tube, in addition to poor hygiene, a weakened immune system, frequent exposure to upper respiratory tract infections, and malnutrition may all contribute to the higher prevalence of ear infections in children compared to that observed in adults.3,8,17 Furthermore, ear infections were slightly more common in men than women (58% vs 42%, respectively), but no significant difference was observed, which agrees with the findings of previous studies.14,18,19
In this study, most of the examined samples (61%) showed axenic cultures, which is consistent with the findings of previous reports.14,20,21 Furthermore, the predominant causative agents were P. aeruginosa, followed by S. aureus, which is also consistent with some previous studies.21-25 However, other studies have reported that S. aureus was the most prevalent pathogen.3,26,27 Recently, Udden et al.28 revealed that Proteus spp. are common pathogens that caused ear infections. The distribution of pathogenic bacteria may differ according to the geographical region and climate variations. P. aeruginosa and S. aureus were the most frequently isolated pathogens in our study, which could be attributed to their ability to form biofilms, compete with other microorganisms for resources, or resist antibiotics. Additionally, P. aeruginosa attaches to the middle ear epithelium, which is necrotic or damaged by the pili. Upon attachment, the microorganism produces enzymes, such as proteases, to bypass the natural defenses of the body against infections.29
In the present study, there were variations in the antibiotic susceptibility patterns of the bacterial isolates. Imipenem and amikacin were the most effective antibiotics against most isolates, followed by ciprofloxacin and gentamicin. Our findings go in line with the results of a study by Al-Ramadi.21 On the other hand, the majority of the isolates were highly resistant to ampicillin and amoxicillin/clavulanic acid, which is consistent with the findings of previous studies.7,8,25,29 The high rates of resistance to ampicillin and amoxicillin/clavulanic acid observed in this study may be attributed to improper use of antibiotics and self-prescription by the patients.
The incidence of ear infections was higher in the age group under 20 years among the patients in Al-Amara city. P. aeruginosa and S. aureus were identified as the predominant causative agents of ear infections. Despite the high rate of multiple drug resistance among the bacterial isolates, imipenem and amikacin were very effective against most of the isolates.
The authors would like to thank all staff of Al-Sadar Teaching Hospital for assistance in the collection of samples.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interest.
All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.
All datasets generated or analyzed during this study are included in the manuscript.
The study was approved by the Ethical Committee of the College of Pharmacy, University of Misan, Maysan, Iraq, with reference number EA313.
Written informed consent was obtained from the participants before enrolling in the study.
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