Kerala Journal of Ophthalmology

: 2020  |  Volume : 32  |  Issue : 1  |  Page : 51--55

Microbial profile of lid margin flora in anterior blepharitis as compared with normal: A comparative, descriptive study

Merie Mathew, Lathika Vasu Kamaladevi, Charles K Skariah 
 Department of Ophthalmology, Amala Institute of Medical Sciences, Thrissur, Kerala, India

Correspondence Address:
Dr. Merie Mathew
Pazhampillil (H), Kummanode, Pattimattom (PO), Ernakulam - 683 562, Kerala


Context: Blepharitis is a condition that causes inflammation of the eyelids, and identification of the common bacterial pathogens along with its antibiotic susceptibility pattern is essential. Aims: The aim of this study is to identify the lid margin flora in a cohort with anterior blepharitis and to compare the microbiological profile with age-matched controls and determine the antibiotic sensitivity pattern of the flora identified. Settings and Design: A comparative, descriptive study was conducted in the Department of Ophthalmology, Amala Institute of Medical Sciences, Thrissur, Kerala, India, over a period of 18 months. Subjects and Methods: The specimen for the microbial study was collected from the concerned eyelids. Smear was prepared, and primary culturing was done to identify the organism, and antibiotic susceptibility testing was performed. Statistical Analysis Used: Statistical Package for the Social Sciences software (version 23) Amala Institute of Medical Sciences, (Thrissur) was used for the statistical analysis. Results: The predominant age group of cases was 40–60 years, with a female preponderance. The bacteria isolated from cases in the order of decreasing frequency were coagulase-negativeStaphylococcus aureus(CoNS) (40.74%), coagulase-positive S. aureus (35.18%), methicillin-resistant Staphylococcus aureus(MRSA) (9.25%), and diphtheroids (5.55%) and were comparable with controls. MRSA and parasites were exclusively isolated from the cases. CoNS was highly sensitive to tetracycline (87.5%), gentamicin (87.5%), and chloramphenicol (85.4%). S. aureus was sensitive to chloramphenicol (95.1%), clindamycin (87.8%), and tetracycline (85.4%). MRSA was 100% sensitive to vancomycin and linezolid. Conclusions: Microbes identified in cases were comparable with that of controls. CoNS was the most common isolate followed by coagulase-positive S. aureus. They both showed high sensitivity to chloramphenicol and tetracycline but were resistant to penicillin. MRSA was sensitive to vancomycin and linezolid.

How to cite this article:
Mathew M, Kamaladevi LV, Skariah CK. Microbial profile of lid margin flora in anterior blepharitis as compared with normal: A comparative, descriptive study.Kerala J Ophthalmol 2020;32:51-55

How to cite this URL:
Mathew M, Kamaladevi LV, Skariah CK. Microbial profile of lid margin flora in anterior blepharitis as compared with normal: A comparative, descriptive study. Kerala J Ophthalmol [serial online] 2020 [cited 2020 Sep 28 ];32:51-55
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Blepharitis is a common condition that causes inflammation of the eyelids, which can be anatomically classified into anterior and posterior blepharitis. It has a complex pathophysiology and can result in significant ocular morbidity. Some systemic and ocular conditions are known to be associated with blepharitis. Bacteria are well implicated in the pathogenesis of blepharitis.[1] For an effective antibacterial treatment, the identification of the common bacterial pathogens causing blepharitis, along with their antibiotic susceptibility pattern, is essential. Thus, the present study aims to find out the prevalent lid margin flora and their antibiotic sensitivity profile in the local population of Thrissur district, Kerala, thereby facilitating the delivery of specific and targeted antibiotics.

 Subjects and Methods

Patients who attended the Ophthalmology Outpatient Department (OPD) in the Amala Institute of Medical Sciences, diagnosed of having anterior blepharitis were included in the study, irrespective of the diabetic status. Patients with concurrent infections of eye and adnexa and partially treated cases were excluded from the study. Patients who were free of other infective or noninfective pathologies of eye, lid, and adnexa were included in the control group.

This was a hospital-based, comparative, descriptive study conducted over a period of 18 months from the date of Institutional Ethics Committee approval. The study group comprised 54 cases of anterior blepharitis and 54 normal age-matched controls without blepharitis. Patients who presented to the ophthalmology OPD and fulfilled the inclusion criteria and did not come under the exclusion criteria were approached and invited to participate in the study after obtaining their informed consent.

Complete history, including the symptoms and presence of probable predisposing factors, were taken. Detailed ocular examination was done in all participants, including visual status, refraction, and anterior segment examination with the slit lamp with special emphasis on examination of lid margin and adnexa.

The specimen for the microbial study was collected from the concerned eyelid of patients having blepharitis and healthy controls by using sterile moistened cotton swabs. The sterile cotton swab was rubbed along the lid margin from punctum to lateral canthus and immediately transferred to the laboratory. Smear was prepared to identify the Gram-positive and Gram-negative organism. Primary culture for aerobic organism was done on Blood agar and MacConkey agar at 37°C and incubated for 24 h [Figure 1] and [Figure 2]. For anaerobic organisms, thioglycollate broth was used, and culture was kept for 7 days before considering negative.{Figure 1}{Figure 2}

Further, biochemical and microbiological analysis was done based on the colony morphology and the characteristics detected on the above-mentioned primary culture media. The results were evaluated by the microbial identification system.

In vitro antibiotic susceptibility testing of the bacteria isolated was performed by the Kirby–Bauer disc-diffusion method. The following antibiotic discs were used with their respective concentration: cloxacillin (1 μg), cefazolin (30 μg), co-trimoxazole (25 μg), tetracycline (30 μg), penicillin (10 μg), chloramphenicol (10 μg), clindamycin (2 μg), ciprofloxacin (5 μg), gentamycin (10 μg), erythromycin (15 μg), vancomycin (30 μg), and linezolid (5 μg). The results were interpreted according to the Clinical Laboratory Standards Institute methodology as sensitive, intermediate, and resistant [Figure 3] and [Figure 4].{Figure 3}{Figure 4}


Among the 54 patients included in the study, the minimum age was 16 years, and the maximum age was 76 years. Their mean age was 44.35 ± 14.62 years.

Of the 54 cases studied, 32 were female and 22 were male, and among the 54 controls, only 20 were female and 34 were male. The difference was statistically significant (P = 0.020, Chi-square test).

Microbiological profile

Microbiological profile of cases

Out of the 54 cases, bacteria were isolated from 49 patients, parasites from three cases, and no organisms were isolated in two cases [Figure 5].{Figure 5}

Microbiological profile of controls

Out of the 54 healthy controls, bacteria were isolated from 49 controls. No organisms were isolated from five controls. Methicillin-resistant Staphylococcus aureus (MRSA) and parasites were absent in controls [Figure 6].{Figure 6}

Comparing the microbiological profile of cases and controls

The microbial profile of cases and controls was comparable, but MRSA and parasites were found exclusively in cases [Figure 7].{Figure 7}

Antibiotic sensitivity profile

Antibiotic sensitivity pattern of coagulase-negative Staphylococcus aureus

Nearly 87.5% of coagulase-negative Staphylococcus aureus (CoNS) were sensitive to tetracycline and gentamycin, and 85.4% were sensitive to chloramphenicol while 77.1% were resistant to penicillin (n = 48) [Figure 8].{Figure 8}

Antibiotic sensitivity pattern of Staphylococcus aureus

Nearly 95.1% of S. aureus were sensitive to chloramphenicol, 87.8% to clindamycin and cefazolin, 85.4% to tetracycline and cotrimoxazole, while 78.0% were resistant to penicillin (n = 41) [Figure 9].{Figure 9}

Antibiotic sensitivity pattern of methicillin-resistant Staphylococcus aureus

Of the MRSA isolated, 100% were sensitive to vancomycin and linezolid, and 60% were sensitive to co-trimoxazole and tetracycline (n = 5) [Figure 10].{Figure 10}


Fifty-four patients with anterior blepharitis were studied and compared with 54 age-matched controls, and the results obtained are discussed hereunder.

Microbiological profile

A general evaluation of microbial flora was done on the samples from patients with anterior blepharitis and compared with controls.

The most common bacteria isolated were CoNS (44.89%) followed by coagulase-positive S. aureus (38.77%). MRSA was isolated from five cases (10.20%) and diphtheroids from three cases (6.12%).

The types of bacteria isolated from all groups of patients and normal persons are similar to those isolated in other comparative microbial profile studies of anterior blepharitis.

This result agrees with the work done by Kulacoglu et al.[2], Dougherty et al.[3], Dong et al.[4] and Schabereiter-Gurtner et al.[5] which showed that many bacteria identified as ocular surface pathogens were found in higher abundance in ocular samples from cases. Hence, it is evident that a balance between the commensal growth and ocular surface pathogen might be important for the prevention of blepharitis.[6]

In the present study, parasites were isolated from only 5.55% (Pthirus pubis – one case, Demodex spp. – two cases). These cases also showed staphylococcal growth.

Antimicrobial susceptibility pattern

Among all bacteria, the overall sensitivity was more for chloramphenicol (85%), tetracycline (84%), and gentamicin (80%). Nearly 76.53% of bacteria were resistant to penicillin.

The study conducted in Libya by Nazeerullah et al.[7] on 56 cases of anterior blepharitis reported that S. aureus showed high susceptibility to ciprofloxacin, vancomycin, gentamycin, and amikacin. High resistance to ampicillin and moderate resistance to chloramphenicol, erythromycin, and cephalexin were shown by S. aureus in the same study.

The sensitivity of bacteria to various antibiotics differs from place to place and in the same place from time to time.[8] Therefore, the changing spectrum of bacteria involved in blepharitis and the emergence of microbial resistance pressurize the need for continuous monitoring to guide empirical therapy.


The most common pathogen isolated from the study group with anterior blepharitis in our population was S. aureus (both CoNS and coagulase-positive S. aureus). Further, antibiotic sensitivity study done showed that these were more sensitive to chloramphenicol and tetracycline followed by erythromycin and quinolones, comparing the antibiotics commonly used in ophthalmic practice. Penicillin is the least sensitive. Hence, we recommend chloramphenicol and tetracycline as the antibiotic of choice in routine cases.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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