الفهرس 
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Abstract
Otitis media (OM) is an inflammation of the middle ear, the
area between the ear drum and the inner ear, including a duct
known as the Eustachian tube. Otitis media is very common in
childhood and this always accompanied by viral upper respiratory
tract infection, mostly caused by influenza virus, with healtheconomic
burden especially in Africa and other developing
nations where the disease prevalence could be as high as 11%. It
may be acute, chronic or recurrent. It can be suppurative or nonsuppurative.
The aetiology and pathogenesis of OM are multifactorial
and include genetic, infections, allergy, environmental, social and
racial factors and Eustachian tube dysfunction.
The current study was undertaken to identify bacterial and
fungal causes otitis media, and investigate the susceptibility of all
local clinical isolates obtained from middle ear of patients
suffering from otitis media to different antimicrobials and
investigate the prevalence and the most prevalent mechanisms of
resistance among different types of isolates.
The study was performed on 85 patients suffering from
otitis media, (acute otitis media, chronic otitis media & chronic
suppurative otitis media); who were attending the out-patient
clinic of ENT Department, Zagazig University Hospitals. They
were 37 males and 48 females. Their ages ranged from 1.5 to 60
years. All patients included in this study were not using local
and/or systemic antibiotics for one week before obtaining the
samples.During this study, a total of 120 isolates were obtained from
85patients. These isolates composed of 94 (78.3%) bacterial
isolates which classified to, 37 (30.8%) Gram positive and 57
(47.5%) Gram negative and 26 (21.7%) fungal isolates which
classified to 24 (20%) mould and 2 (1.67%) yeast.
The bacterial isolates comprised 25 (20.8%) Pseudomonas
aeruginosa, 21 (17.5%) Staphylococcus aureus, 16 (13.3%)
Streptococcus pneumoniae, 15 (12.5%) Proteus mirabilis, 8
(6.7%) Escherichia coli, 5 (4.2%) Haemophilus influenzae and 4
(3.3%) Klebsiella pneumoniae, while the fungal isolates
comprised 18 (69.2%) Aspergillus niger, 6 (23.1%) Aspergillus
fumigatus and 2 (7.7%) Candida albicans.
In the present study, antibiotic susceptibility tests revealed
that Staphylococcus aureus isolates were 100% susceptible to
vancomycin and imipenem, but showed high resistant to
ampicillin 011%, oxacillin 015.% and tetracycline 2.57%.
Pseudomonas aeruginosa isolates were 100% sensitive to
ceftazidime and 96% sensitive to imipenem and regarded it as the
most effective antibiotic. Regarding Proteus mirabilis isolates, the
most active agents were cefotaxime and cefepime 100%
susceptibility followed by amoxicillin-clavulanic acid 93.3%,
imipenem and amikacin 86.7%, piperacillin and gentamicin
73.3% and ciprofloxacin 66.7%. S. pneumoniae isolates were
100% susceptible to ciprofloxacin, levofloxacin, clarithromycin,
cefotaxime, amoxicillin-clavulanic acid, vancomycin and
imipenem, the lowest resistance rates were found to erythromycin
and clindamycin were 6.3% and high resistance was 31.2% to
oxacillin. Escherichia coli isolates, all of them were 100%susceptible to imipenem, cefepime, cefotaxime and
chloramphenicol. The highest resistance rate for Escherichia coli
isolates was found to tetracycline (75%), while resistance rate to
each of sulfamethoxazole/trimethoprim, gentamicin and
ciprofloxacin was 37.5%. The resistance rate to piperacillin was
50%. The lowest resistance rate (12.5%) was found to each of
amoxicillin-clavulanic acid and amikacin. Klebsiella pneumonia
isolates, all of them were 100% susceptible to imipenem,
levofloxacin, amoxicillin-clavulanic acid, cefepime and
chloramphenicol. The highest resistance rate for Klebsiella
pneumoniae isolates was found to each of tetracycline and
sulfamethoxazole/trimethoprim (75%). the lowest resistance rate
of Klebsiella pneumonia isolates was found to each of cefotaxime
and ciprofloxacin (25%). Haemophilus influenzae isolates, all of
them were 100% susceptible to imipenem, levofloxacin,
azithromycin, aztreonam, ciprofloxacin, cefotaxime and
amoxicillin-clavulanic acid. The highest resistance rate for
Haemophilus influenzae isolates was found to ampicillin (80%).
All fungal isolates (100%) were sensitive to Itraconazole and
Amphotericin B.
Our study showed that P. aeruginosa, S. aureus, S.
pneumoniae, P. mirabilis and Aspergillus niger were the most
important organisms associated with otitis media. For Gramnegative
bacteria imipenem, amoxicillin-clavulanic acid,
cefotaxime, levofloxacin and amikacin are the most effective
antibiotics to treat chronic suppurative otitis media. Similarly, for
Gram-positive bacteria imipenem, vancomycin,sulfamethoxazole/trimethoprim, levofloxacin, ciprofloxacin and
clindamycin are the most effective antibiotics.
These phenotypic confirmatory tests showed one positive
Klebsiella pneumoniae isolate was EBLs producer.
The frequent resistance among P. aeruginosa isolates to the
existing antipseudomonal agents were 100% through overexpression of
multidrug efflux pumps proved by determination of MICs of selected
antibiotics on some multi drug resistant (MDR) P. aeruginosa isolates
before and after addition of CCCP.
PCR amplification demonstrated the acquired erm-A gene in 1 S.
aureus isolate that had resistant to erythromycin and clindamycin and
demonstrated the acquired mec-A gene in 13 S. aureus isolates (13
MRSA strain).