Prevalence and Drug Susceptibility Pattern of Bacterial Pathogens from Ocular Infection in St. Paul’s Hospital Millennium Medical College, Ethiopia

Research Article

J Bacteriol Mycol. 2018; 5(8): 1085.

Prevalence and Drug Susceptibility Pattern of Bacterial Pathogens from Ocular Infection in St. Paul’s Hospital Millennium Medical College, Ethiopia

Aklilu A¹*, Bitew A², Dessie W², Hailu E³, Asamene N5, Mamuye Y4 and Woldemariam M6

¹College of Health Sciences, Arbaminch University, Ethiopia

²College of Allied Health Sciences, Addis Ababa University, Ethiopia

³Department of Ophthalmology, St. Paul Hospital Millennium Medical College, Ethiopia

4Department of Medical Microbiology, St. Paul Hospital Millennium Medical College, Ethiopia

5Ethiopian Public Health Institute, Ethiopia

6College of Allied Health Sciences, Addis Ababa University, Ethiopia

*Corresponding author: Addis Aklilu, College of Health Sciences, Arbaminch University, Ethiopia

Received: October 26, 2018; Accepted: November 21, 2018; Published: November 28, 2018


Background: Ocular infection is a major public health problem in developing countries. It is main causes of morbidity and blindness worldwide. The aim of this study was to assess the prevalence of bacterial pathogens among external ocular infection attending St. Paul Hospital Millennium Medical College.

Methodology: A facility based cross sectional study was conducted from April to August 2016. Conjunctival and eyelid margin swabs and corneal scraping were collected. Demographic data were collected using structured questionnaire. All Specimens were processed for microbiological analysis as per standard procedures. The data was analyzed using SPSS version 20. P-value <0.05 was considered as statistically significant.

Results: A total of 215 patients were enrolled in this study. Almost half of the study participants were males 109(50.7%). The mean age of the study participants was 42.34 (Sd.±20.55) and majority were within the age range of 25-44 years 72(33.5%). About 118(54.9%) were found to be culture positive. Staphylococcus aureus 32(27.1%) was the commonest isolate followed by coagulase negative Staphylococci25 (21.2%). Ceftriaxone 38(97.4%), Gentamycin 76(96.2%), Tobramycin 70(88.6%), were effective. Gram positives and gram negatives were showed high resistance against Penicillin 66/88(75%) and Ampicillin 20/27(81.5%) respectively.

Conclusion: The prevalence and drug resistance of bacterial pathogens was higher among external ocular infection.

Keywords: External ocular infections; Conjunctivitis; Blepharitis; Dacryocystitis; Susceptibility


ATCC: American Type Culture Collection; CLSI: Clinical and Laboratory Standard Institute; CoNS: Coagulase Negative Staphylococci; DST: Drug Susceptibility Testing; MDR: Multidrug Resistance; MRCoNS: Methicillin Resistant Coagulase Negative Staphylococci; MRSA: Methicillin Resistant Staphylococcus aureus; SPSS: Statistical Package for Social Science; WHO: World Health Organization


Ocular infection is a major public health problem in developing countries including Ethiopia. Bacteria, viruses, fungi and parasites can cause these ocular infections [1,2]. Bacteria are the most common microorganisms that cause external ocular infections. This is because the bacterial pathogens inhabit the ocular surface [3,4].

Haemophilus influenza and Streptococcus pneumoniae in children and Staphylococcus aureus in adults are the commonest bacteria causing ocular infection. Multidrug resistant bacteria isolates like Methicillin-resistant S. aureus (MRSA) are emerging more important pathogen. But, generally gram positive pathogens are responsible for 60% to 80% of acute infections [4-6].

The external ocular infections are responsible for increased incidence of morbidity and blindness world widely. Keratitis is a major cause of vision loss and blindness second to cataract and is the most common in developing countries. Blepharitis can also result in patient discomfort and decrease in vision. Moreover, untreated lacrimal abscess can progress to orbital cellulitis, superior ophthalmic vein thrombosis and these may lead to life threatening infections. Infections of the conjunctiva can also spread to the cornea and cause a perforation [1,7-10]. Bacterial infection is a common cause of conjunctivitis and accounts for up to 50% of all cases of conjunctivitis in adults and 70% to 80% of all cases in children [4,11].

In Ethiopia the prevalence of blindness was about 1.6% and it is estimated that 87.4% of the cases are caused by untreated bacterial, viral and fungal infections. The prevalence of bacterial infections and development of multidrug resistance are becoming increasing in country this makes difficult in treatment of external ocular infections where the diagnosis is without laboratory confirmation [2,9,13].

Multidrug resistance is becoming the very serious problem. The emergence of bacterial resistance towards antimicrobial agents may increases the risk of treatment failure. In our country, the blindly use of antibiotics without physicians prescription may contribute the increasing of drug resistance [13,14]. The antibiotic susceptibility pattern of bacterial isolates which are implicated to cause ocular infections must be evaluated periodically. Therefore, the aim of this study was to assess the antibiotic susceptibility profile of bacterial pathogen from external ocular infections among patients attending St. Paul Hospital Millennium medical college.

Method and Materials

Study design, period and area

A facility based cross sectional study was conducted from April to August, 2016, at St. Paul’s Hospital Millennium Medical College, which is a referral hospital in Addis Ababa under the Ethiopian Federal Ministry of Health (FMOH). It is the second largest public hospital in the nation, built by the Emperor Haile Selassie in 1961 with the help of the German Evangelical Church. The hospital was established to serve the economically under privileged population, providing services free of charge to about 75% of its patients. It is providing medical specialty services to an estimated 110,000 people annually who are referred from all over the country.

Source population

All patients who were attended St. Paul hospital Millennium medical college eye clinic

Study population

All patients attended St. Paul hospital Millennium medical college eye clinic clinically suspected with ocular infections

Eligibility criteria

Inclusion criteria

• Clinically diagnosed patients suspected with external ocular infections.

• Patients who were willing to give their consent were enrolled in this study.

Exclusion criteria

• Patients on topical antibiotics treatment.

Sampling technique

Systematic random sampling technique was used by taking the first participant with lottery method from the first three patients then the other participants were recruited in every 3 individuals and a total 215 ocular sample were collected from April to August 2016.

Data Collection and Laboratory Analysis

Specimen collection and transportation

Upon admission to the hospital, patients were examined physically and with the help of slit lamp microscope for external ocular infections by the ophthalmologist. During examination 2 to 4 conjunctival and eyelid swabs were collected aseptically by using sterile cotton tipped swab pre-moistened with sterile physiological saline by asking the patient to look up, the lower lid was pulled down using thumb with an absorbing tissue paper and the swab was rubbed over the lower conjunctival sac from medial to lateral side and back again. Pus from lachrymal sac was collected using dry sterile cotton tipped swab either by applying pressure over the lachrymal sac and allowing the purulent material to reflux through the lachrymal punctum. Corneal scraping was collected after instilling 2 to 3 drops of local anesthetic (Tetracaine hydrochloride 0.5%) into the conjunctiva and patient was asked to wait for 2 to 3 minutes and corneal surface was cleaned for debris and discharge using dry sterile cotton tipped swab and with the help of slit lamb the edge of the ulcer was scraped using 21gauge needle. All swabs and the scraped material obtained on the needle directly were transferred into amies transport media and Brain Heart Infusion Broth 2ml (BHIB) (Oxoid, Basingstoke, UK) respectively [15,16]. All samples were transported to clinical bacteriology and mycology laboratory of Ethiopian Public Health Institute (EPHI). All ocular samples were collected by the ophthalmologist. Demographic data, clinical data and associated factors of study participant were collected by using pretested structured questionnaire and face to face interview.

Laboratory Processes

Bacterial cultivation and Identification

All swab samples were inoculated onto Blood agar base (Oxoid, Basingstoke, UK) to which 10% sheep blood is incorporated, chocolate agar/heated blood agar (Oxoid, Basingstoke, UK) and MacConkey agar (Oxoid, Basingstoke, UK). The inoculated cultures were incubated at 37°C for 24 hours with in candle jar (5-10% CO2) except MacConkey agar and if no growth under overnight incubation re-incubated for further 24 hours. Pure isolates of bacterial pathogen were preliminary characterized by colony morphology, gram stain, and catalase and hemolytic reactions on blood agar plates. Identification of bacteria down to species level was done by employing an array of routine biochemical tests such as catalase, coagulase, Optochin test and Bacitracin test for gram positive identification and oxidase test, motility test, indole production test, Urease test, citrate utilization test, lysine decarboxylation test, carbohydrate fermentation, gas production and H2S production for gram negative bacterial identification and using X and V factors test for Haemophilus species identification [17,18].

Drug susceptibility testing

A modified Kirby-Bauer disc diffusion technique for Drug Susceptibility Test (DST) was performed among all identified bacterial isolates as recommended by Clinical and Laboratory Standard Institute (CLSI), 2015 on Mueller-Hinton agar and Mueller- Hinton agar supplemented with 5% sheep blood for fastidious bacterial isolates (Oxoid Ltd Basingstoke, Hampshire, UK). The bacterial suspension prepared equivalent to the McFarland standard (0.5 CFU) was seeded on Muller-Hinton agar and after few minutes put the paper impregnated antibiotic disks (Oxoid Ltd Basingstoke, Hampshire, UK) then incubate for 18-24hrs at 37°C based on the organisms tested. Diameters of the zone of inhibition around the discs were measured to the nearest millimeter using a caliper and classified as sensitive, intermediate, and resistant. The following antibiotics which are currently recommended by CLSI version 2015 were tested such as: Amoxicillin-clavulanic acid (20/10μg), Ampicilin (10μg), Amikacin (30μg), Gentamycin (10μg), Erythromycin (15μg), Ceftriaxone (30μg), Ciprofloxacin (5μg), Norfloxacine (10μg), Tetracycline (30μg), Trimethoprim-sulphamethoxazole (1.25/23.75μg), Penicillin (10μg), Vancomycin (30μg), Clindamycin (2μg), Cefoxitin (30μg), Oxacillin (30μg), Chloramphenicol (30μg), Piperacilin (100μg), Tobramycin (10μg), Ceftazidime (10μg) and Meropenim (10μg). Bacterial isolates which were resistant for two or more classes of antibiotics were considered as Multidrug Resistant (MDR) [18,19].

Quality Control

To maintain the quality of the work from sample collection up to final laboratory identification the standard operating procedure of sample collection and laboratory analysis were followed strictly. All the equipment were checked for their proper functionality. The prepared culture media were checked for sterility by incubating the five percent for overnight and observe for the presence of any growth. Capacity of the prepared media supporting the growth of organisms was checked by inoculating control strains. The known control organisms were used such as S. aureus (ATCC 25923), E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853). Questionnaires used to collect demographic data and associated factors were pretested prior to data collection and supervision of the data collection was done regularly on daily basis and in which incompletely filled questionnaires were discarded.

Statistical Analysis

Data were collected, entered, cleaned and analyzed using SPSS version 20 software according to the study objectives. The descriptive summaries were presented with text and tables. Binary logistic regression was used to determine the association between the prevalence of bacterial pathogens and selected demographic characteristics and associated risk factors. P-value less than 0.05 were considered as statistically significant.

Ethical Consideration

Ethical clearance was obtained from Departmental Research and Ethical Review Committee (DRERC) of Medical laboratory Science, School of Allied Health Science, College of Health Science, Addis Ababa University and St. Paul’s Hospital Millennium Medical College. The permission from the hospital management office was obtained. Written informed consent was also obtained from each study participants. Study participant’s confidentialities were strictly maintained during the interview process as well as anonymity was kept during data processing and report writing. Laboratory confirmed cases were treated with effective antibiotics tested. So that patients were benefited from this study.


Demographic characteristics of study participants

A total of 215 patients with external ocular infection were enrolled in this study. Majority of the participants were males 109 (50.7%). The mean age of the study participants was 42.34(Sd.±20.55) and majority of participants age were within the age range of 25-44 years 72(33.5%). Most of the participants lives in urban 152(70.7%), literate 109(50.7%) and house wives 51(23.7%) in occupation. On the other hand, 34(15.8%) and 32(14.9%) of study participants had trauma history and previous eye surgery respectively. Most of study participants had less frequent face washing habit 109(50.7%) and 21(9.8%) had chronic diseases (Table1).