Types and drug susceptibility patterns of bacterial isolates from eye discharge samples at Gondar University Hospital, Northwest Ethiopia

Eye is one of the sense organ which is important throughout our life. The awareness given to eye health and cleanliness is vital due to many factors. Dust, high temperature, microorganisms and other factors can lead to various eye diseases which can lead to blindness. The clinical signs and symptoms of inflammation of the eyes, in the presence of mucous pus are frequently caused by bacteria, the formation of pus increase, conjunctival hyperemia and lid edema [1, 2].

Bacteria causes eye disease because of their virulence and host's condensed fighting from various factors such as socio-economic status, individual hygiene, lifestyle, nutrition, inheritance, physiology, and age [3]. Eye may be infected by being exposed to outside influences and internal invasion of bacteria that are transported by the blood stream [4]. External microbial infections of the eye are usually centralized in one place but may frequently distributed to other tissues. The conjunctiva and eyelid have a normal microbial flora controlled by its own mechanism and by the host. Any change of this normal flora leads to ocular infections [5, 6].

Bacterial conjunctivitis is an inflammatory condition of the conjunctiva that results from infection due to one or more bacterial species. Most cases of acute bacterial conjunctivitis pointed eye are common and can affect both sexes and all age groups [7]. The common bacteria that causes eye infection are: Pseudomonas aeruginosa, Proteus spp, Haemophilus aegyptius, Neisseria gonorrhoeae, Moraxella spp such as Moraxella catarrhalis, Moraxella lacunata, Streptococcus pyogenes, and Staphylococcus aureus[8]. The microbial etiology and drug susceptibility as well as resistance profile may differ with geographic location according to the restricted inhabitants [9].

Bacterial eye infection needs instant institution of treatment. Treatment of bacterial eye infections may engross empirical treatment with topical ophthalmic broad-spectrum antibiotic formulations that become a prevailing practice among ophthalmologists and general practitioners. These jointly with irrational use of drugs, availability of antibiotics without prescription, have led to the development of resistance to commonly used antibiotics. Thus, the current trends in the etiology of bacteria that cause eye infections and their susceptibilities must be updated to make a rational choice of initial antibiotic therapy. The aim of this study was to determine bacterial isolates and drug susceptibility patterns of eye discharge at Gondar University Hospital.

A total of 102 patients who gave eye discharge sample to bacteriological analysis were enrolled.

Of all, 65 (63.7%) were males and 37 (36.3%) were females. The mean age of the study subjects was 8.5 years, ranges from 1 day of life to 73 years old. Bacterial isolation in both sexes (P-value = 0.27) and various age groups (P-value = 0.59) was not showed statistically significant.

In this study, the overall prevalence of bacterial eye infection was 60.8%. Similar findings have been reported in previous study conducted in Ethiopia, (54.2%) [12] and other countries such as: Niger (66.70%) [13], Nigeria, (69.2%) [14] and India (58.8%) [15]. The predominant bacterial isolates were Coagulase-negative staphylococci (27.42%) followed by S. aureus (20.97%). This finding is in agreement with previous study [12]. However, in other studies [15], the predominant isolates were S. aureus followed by S. Pneumoniae. This may be due to the difference in climate and geographical variations in different countries. Other isolates included S. pneumoniae (11.3%), S. pyogene (14.5%), E. coli (8.1%), Klebsella spps (14.5%), and non lactose fermentor gram negative rods (3.2%). These results are consistent with the study by Kasper et al.,[16]. Forty 40 (39.21%) samples were not showed bacterial growth. This might be due to the possibility of the presence of other micro-organisms which may cause eye infection such as viral causes or Chlamydia [17] or fungi causes especially yeasts [18].

The majority of the bacterial isolates, (66.1%) were from patients in the age range of less than two years of life. Susceptibility to infection is increased in babies because they are at a greater risk after their maternal immunity has been disappeared and before their own immunity system had matured [3]. In addition to this, the air plays an important role in the transfer of bacteria to hospital delivery rooms especially when opening the doors and windows which facilitates transfer it to the baby [19].

Commonly used antibiotics in a study area were; tetracycline, erythromycin, chloramphenicol, gentamicin, ciprofloxacin, Trimethoprim-sulphamethoxazole, penicillin, ceftriaxone, norflaxocin and amoxicillin. However, in the present study, different bacterial species had high level of resistance pattern to different antimicrobial agents. For example, Coagulase-negative staphylococci showed high level of resistance to ampicilin (76.5%), amoxicilin (64.7%), erythromycin and tetracycline each (64.7%), gentamicin (58.8%), penicillin and trimethoprim-sulphamethoxazole each (70.6%). This is in agreement with the previously studies [20]. The sensitivity of Staphylococcus aureus isolates to antimicrobials used showed the highest sensitivity to ciprofloxacin with percentage (84.6%) followed by ceftriaxone with percentage (76.9%) while the proportion was less sensitive to ampicilin with percentage(23.1%), penicillin and trimethoprim-sulphamethoxazole, (30.8%) each. This result is consistent with the previously studies [21]. It is well known fact that most S. aureus strains produce pencillinase and alternative penicillin binding proteins (PBP-2A) helps the organisms to become resistant to most beta lactam antibiotics [22].

In this study, most of bacterial isolates have shown high resistance to ampicilin (71%), penicillin (71%), amoxicilin (62.9%), tetracycline (64.6%), trimethoprim-sulphamethoxazole (58.1%), and erythromycin (43.5%). Similar findings have been reported in Iran [23] and in Aligarh [24]. Many studies reported indiscriminate use of antibiotics as the reason for drug resistance in microbial population [25] while ceftriaxon (75.8%) and ciprofloxacin (80%) showed susceptibility. This finding is comparable to other reports [26].

Prevalence of multidrug resistance (MDR) to two or more of bacterial isolates to the commonly prescribed antimicrobials was observed in 87.1% of the isolates. This is in agreement with the previous studies [27, 28]. However, low prevalence of multidrug resistance was previously reported by Moreillon [22]. High prevalence of MDR in our study might be due to an irrational and unnecessary use of antimicrobial agents which can result in the emergence of bacterial strains that show multidrug resistance [29].

The prevalence of bacterial isolates in eye discharge was high in the study area and majority of isolates were gram-positive bacteria. The predominant isolates were Coagulase-negative staphylococci and S. aureus. Most of the bacterial isolates were resistant to commonly used antimicrobials. Therefore, drug susceptibility test is essential before prescribing any antimicrobials.