الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
CSOM is a major public health problem and one of the most common diseases of the
ear for all age groups. It is defined as a chronic inflammation of the mucoperiosteal lining
of the middle ear cleft, which presents with recurrent or persistent ear discharges through a
TM perforation.
Risk factors associated with CSOM include recurrent episodes of AOM, upper
respiratory tract infections, and traumatic TM perforation as well as factors correlating
with resource-limited living conditions such as overcrowding, poor nutrition and hygiene
and chronic infectious diseases. Even if the pathogenesis of CSOM is multifactorial, the
clinical onset is frequently an episode of AOM complicated by TM perforation and a
subsequent superinfection of the middle ear with bacteria entering through the external ear
canal.
Microbiological findings in CSOM vary between studies. However, the bacterial
spectrum most often identified is dominated by P. aeruginosa, S. aureus and
Enterobacteriaceae such as Proteus spp. and K. pneumoniae.
Inadequate and inappropriate treatment of CSOM can result in a wide range of
complications. These may be due to the spread of organisms to structures adjacent to the
ear or to local damage in the middle ear itself. Also, CSOM is an important cause of
preventable hearing loss particularly in the developing countries and a reason of serious
concern, particularly in children, because it may have long-term effects on early
communication, language development, auditory processing, educational process, and
physiological and cognitive development. Early and effective treatment based on the
knowledge of causative microorganisms and their antimicrobial sensitivity ensures prompt
clinical recovery and possible complications can thus be avoided.
The present study aimed to:
1- Isolate and identify microorganisms associated with CSOM.
2- Detect the antimicrobial susceptibility of aerobic bacterial isolates.
The study was conducted over a period of one year from September 2017 to August
2018. It enrolled 143 patients with symptoms and signs of active CSOM attending the
outpatient clinics of the Otorhinolaryngology Department at AMUH. One hundred and
sixty samples were collected from those patients.
Ear discharge was aseptically collected from each patient by the attending physician
using three separate sterile swabs. The 1st swab was dipped immediately into a screwcapped
sterile tube of Amies transport medium. The 2nd swab was inoculated immediately
in RCM broth and the 3rd swab was placed in a sterile tube. The swabs were labeled and
transported as soon as possible to the Microbiology Laboratory at HIPH. The 1st swab was used for aerobic culture and was plated directly on each of 5% BA,
MacConkey’s agar and CA plates. The BA and MacConkey’s agar plates were incubated
aerobically while CA plate was incubated in 5% CO2 atmosphere at 37°C for 24-48 hours.
The 2nd swab was used for anaerobic culture and was incubated at 37°C for 72 hours. On
the 3rd day, subculture from RCM was made on neomycin blood agar with metronidazole
5μg disc and incubated anaerobically at 37°C for 72 hours. The 3rd swab was inoculated on
two SDA plates containing 0.05 mg/ml of chloramphenicol and then one of these plates
was incubated at 28°C and the other at 37°C for one week.
After proper incubation, identification of isolated colonies was performed according
to the standard microbiological methods. All aerobic bacterial isolates (except Achromobacter xylosoxidans) were subjected to antibiotic susceptibility testing by disc
diffusion method. The Achromobacter xylosoxidans isolate was subjected to antimicrobial
susceptibility testing using VITEK MS automated identification system. The prevalence of
vancomycin resistance among the S. aureus isolates was determined by MIC using agar
dilution method.
The results of the present study revealed that:
1. There was a significant association between age and clinical picture, where
hearing impairment was higher in the age group of 18-40 years (47.57%) and no
total TM perforation was found in the age group of <18 years.
2. Laterality of CSOM was significantly affected by swimming in the sea, where 16
(94.12%) out of 17 bilateral cases were associated with a history of swimming in
the sea.
3. Out of 160 cultured samples, 8 (5.00%) yielded no growth, 129 (80.62%) yielded
bacterial growth only, 8 (5.00%) yielded fungal growth only and 15 (9.38%)
yielded mixed bacterial and fungal growth.
4. Out of 153 bacterial isolates, 86 (56.21%) were gram negative aerobes, 65
(42.48%) were gram positive aerobes and only 2 (1.31%) were anaerobes.
5. The most common bacterial isolate was P. aeruginosa (24.83%), followed by S.
aureus (22.22%). They were followed by CoNS and P. mirabilis (13.07% each)
and K. pneumoniae (5.22%).
6. The most common fungal isolate was A. flavus (45.83%) followed by A. niger
(25.00%) and then C. albicans and NAC (12.50% each) and Penicillium spp.
(4.17%).
7. There was a significant association between type of discharge and culture result,
where most of watery discharge (60.87%) was associated with gram positive
isolates, while all mucoid discharge and majority of mucopurulent discharge
(86.11%) were associated with gram negative isolates.
8. There was a significant association between type of TM perforation and culture
result, where all the subtotal perforations were associated with positive microbial
culture results and the majority of them (84.09%) were associated with bacterial
infections 9. The highest susceptibility percentages of P. aeruginosa isolates were recorded for
piperacillin-tazobactam (92.1%) followed by imipenem (83.8%) and then
ceftazidime (65.8%), while the lowest were recorded for ciprofloxacin (42.1%)
followed by tobramycin (50.0%).
10. The highest susceptibility percentages of S. aureus isolates were recorded for
linezolid and rifampin (94.1% each) followed by trimethoprim-sulfamethoxazole
(88.2%), while the lowest were recorded for penicillin (5.9%) followed by cefoxitin
(50.0%) and then gentamicin (58.8%). Half of S. aureus isolates were MRSA,
while 3 (8.82%) were VRSA.
11. Only 77 (50.33%) bacterial isolates were sensitive to ciprofloxacin.
12. Seventy-one (46.41%) bacterial isolates were MDR and most of them were S.
aureus (12.42%), followed by P. aeruginosa (9.81%) and P. mirabilis (7.84%).
13. Six (3.92%) bacterial isolates were PDR.
14. There was a significant association between previous treatment history and MDR,
where the majority of MDR bacteria (95.77%) were associated with a previous
treatment history related to CSOM.
It can be concluded from the present study that:
1. The most common cause of the studied CSOM infections was P. aeruginosa
(23.75%), followed by S. aureus (21.25%).
2. There were significant associations between both type of discharge and type of TM
perforation and culture results.
3. Half of S. aureus isolates were MRSA, while 3 (8.82%) were VRSA.
4. Seventy-one (46.41%) bacterial isolates were MDR, while 6 (3.92%) were PDR and
there was a significant association between the previous antibiotic treatment history
for CSOM and the development of MDR bacteria.
5. Linezolid was the most effective antibiotic against the gram positive isolates, while
imipenem was the most effective against the gram negative isolates.
6. Only 50.33% of isolated bacteria were found to be sensitive to ciprofloxacin
prescriped by physicians at the outpatient clinics of the Otorhinolaryngology
Department at AMUH. the results of the present study, the following recommendations are
suggested:
1. Treatment should be based on results of culture and antibiotic susceptibility tests
instead of the usual trend of empirical treatment to avoid overuse of unnecessary
antibiotics that eventually lead to the emergence of MDR and PDR bacteria.
2. Fungal infection can occur in CSOM without specific clinical signs, therefore,
empirical topical antifungal and antibacterial therapy is recommended before results
of culture and sensitivity.
3. Although linezolid and imipenem were the most effective antibiotics in the present
study, there are no available topical otic preparations of both of them in Egypt.
Therefore, the Egyptian pharmaceutical companies are recommended to
manufacture novel topical otic antibiotic preparations.
4. Continuous and periodic surveillance of microbiological pattern and monitoring of
antibiotic resistance profile to guide appropriate antimicrobial therapy.