International Journal of Pharma and Bio Sciences

Transcription

1 Research Article Microbiology International Journal of Pharma and Bio Sciences ISSN INFECTIVE KERATITIS - PREDISPOSING FACTORS, CLINICAL AND MICROBIOLOGICAL ANALYSIS WITH ANTIBIOTIC SUSCEPTIBILITY PATTERNS DR. KALA YADHAV M L * 1 AND SYED AHMED 2 1. Associate professor of Microbiology, BMCRI, Bangalore. 2. Final MBBS student, BMCRI, Bangalore. ABSTRACT Infective keratitis is a serious ocular disease that can lead to severe visual disability.the annual incidence of microbial keratitis is reported to be 11.3 per people in India. AIMS: To identify and determine the association between risk factors and microbiological etiology and to study the antibiotic susceptibility patterns. MATERIALS AND METHODS: The study included 142 cases, of which 55 cases were subjected to detailed clinical examination, culturing of the samples and antibiotic susceptibility testing was done according to standard protocols. RESULTS: Corneal trauma was a major risk factor accounting for 65.4% of cases and 60% of affected patients were involved in agricultural practices with significant male preponderance (65%). Of the 55 cases, 36 showed positive cultures, where bacterial keratitis was predominantly caused by Staphylococcus species and fungal keratitis by Aspergillus species. In this study bacteria were susceptible to vancomycin (100%), ciprofloxacin and chloramphenicol (87.5%) and gentamycin (75.0%). CONCLUSION: To conclude, this study highlights the burden of infective keratitis on our health care set up, the important preventable risk factors and causative organisms. KEYWORDS: keratitis, corneal trauma, Staphylococcus aureus, Aspergillus sp. DR. KALA YADHAV M L Associate professor of Microbiology, BMCRI, Bangalore. B - 473

2 INTRODUCTION Infective keratitis is a serious ocular disease that can lead to severe visual disability 1. Corneal diseases, especially infective keratitis are a major cause of vision loss and blindness second only to cataract [2]. It is a major public health problem in developing world, as sufferers are exposed to prolonged morbidity, loss of vision and many times loss of eyes. A study from south India reported that the incidence of corneal infections in India is almost 10 times that reported in USA [3]. The annual incidence of microbial keratitis is reported to be 11.3 per people in India [4]. Infective keratitis rarely occurs in normal eyes without any predisposing factors. Infective keratitis may be caused by bacteria, fungi, protozoa and virus. An association has been shown between the type of risk factor and the microbial etiology of infection. Predisposing factors include, corneal epithelial disruption caused by trauma, contact lens wear, contaminated ocular medications and impaired immune mechanisms (5). Treatment of infective keratitis especially corneal ulcers has at best remained unsatisfactory across the health systems of the developing world. Each year, new antimicrobials are found or synthesized in an effort to improve the chance of overcoming infections [6]. Adequate ocular prevention, knowledge of microbiological pattern in a given clinical practice, a prompt choice of appropriate fortified antimicrobials, initiation of immediate therapy, modification based on organism identified and consideration of drug toxicity and bacterial resistances represent the keys to success in the management of infective keratitis. Hence this study was undertaken. Aims and objectives The aims and objectives of this study are: i. To identify the risk factors predisposing to infective keratitis (non viral) and attempt to determine the association between risk factors and microbiological etiology. ii. To identify the etiological organisms of infective keratitis in current practice iii. To study the in vitro efficacy of commonly used antimicrobials against the pathogens. MATERIALS AND METHODS This study was undertaken for a period of two months, a total of 142 patients presented with symptoms of keratitis, out of which 55 of them were clinically diagnosed as infective keratitis presenting with corneal infiltrates were enrolled in this study. Inclusion criteria- All patients clinically diagnosed as infective keratitis with corneal infiltrates presenting at our tertiary care hospital. Exclusion criteria- Patients with chronic ulceration lasting for 3 weeks or more were excluded. Patients presenting with viral or Acanthamoeba infection were excluded. Clinical procedure All patients enrolled in the study underwent detailed investigations, that included a) The documentation of age, address, occupation, duration of symptoms, therapy received prior to presentation and use of traditional medicines. b) Information of predisposing factors like history of injury, injurious agents, associated ocular diseases like cataract, glaucoma, use of contact lenses and use of topical steroids and presence of systemic diseases. c) Ocular examination was done by using a slit lamp bio microscope. After a detailed ocular examination, corneal scrape was performed under magnification of a slit lamp or operating microscope following 0.5% lignocaine hydrochloride by using the sterile syringe or a sterile Bard-Parker blade#15 under strict aseptic conditions. B - 474

3 Microbiological procedures. The scraping material obtained from each is initially inoculated directly onto the surface of solid media such as Brain Heart infusion agar and broth, sheep blood agar, Chocolate agar and sabourand s dextrose agar in a row of C shaped streaks. Meticulous care is taken while collecting the material aseptically and transferring it to the appropriate culture media. Inoculated media are incubated aerobically at 37 0 C, evaluated at 24 and 48hrs and then discarded if no growth is seen. Sabourand s dextrose agar is incubated at 37 0 C and 27 0 C with and without antibiotics, examined daily and discarded at 3 weeks if no growth is seen. Microbial cultures were considered positive only if the following criteria were met The growth of the same organism on two or more solid media on the C streak; semi confluent growth at the site of inoculation on one solid medium. The same organisms grown from repeated scraping. The growth is consistent with clinical signs. Microscopy consistent with cultures, associated with the identification of the organism of appropriate morphology and staining characteristics of corneal smears. The organisms were identified using standard biochemical tests and antibiotic susceptibility test was done. All laboratory methods were followed according to standard protocols given by CLSI guidelines [7]. Statistical analysis of data Descriptive study was done in percentages, frequencies and appropriate graphical representation. For analytical study, Chi square test was used. OBSERVATIONS AND RESULTS 1) Age and sex distribution. Of the 55 patients enrolled 36(65.4%) were males and 19(34.5%) were females, indicating a higher incidence among males. The age group of in males and above 60 in females had a higher incidence of corneal ulcers as seen in table 1. Table 1 Age distribution of the total number of cases Age Male Female (2.7%) 0 (0.0%) (8.3%) 1 (5.2%) (16.6%) 1 (5.2%) (27.7%) 3 (15.7%) (25.0%) 6 (31.5%) Above 60 7 (19.4%) 8 (42.1%) 2) Relation between age group and associated predisposing factors. Table 2 Relation between age group and associated predisposing factors. Age group In Years Corneal trauma Vegetable matter induced Other trauma Contact lens induced Non-traumatic Post keratoplasy Above Total Percentag es (65.4%) (3.6%) (27.4%) (3.6%) B - 475

4 Of the total 55 cases, 36 cases (65.4%) were due to corneal trauma of which 17 cases (47.3%) were vegetable matter induced and rest 19 cases (52.7%) were due to other forms of corneal trauma like fall of foreign body, dust particles etc. 15 cases (27.4%) were non-traumatic and had no significant predisposing factors. 2 out of 55 cases (3.6%) were post keratoplasty and two cases (3.6%) were due to contact lens wear. The age groups above 50 were particularly susceptible for corneal trauma and Post keratoplasty induced keratitis was found exclusively in the age group of above 60 years. 3) Occupational status of patients with microbial keratitis. Most of the cases of corneal ulcer cases were related to outdoor occupation like agriculture (60.0%) and manual labour (23.6%) while indoor activities like desk job ( 7.2%) and household work (9.1%) had lower cases. 4) Co-relation between predisposing factors and microbial etiology. Of the 55 corneal ulcers, 36 (65.4 %) cases were culture positive out of which 38 organisms were isolated. Among these 30 (83.3%) yielded pure bacterial isolates, 4 (11.1%) pure fungal isolates and 2(5.5%) showed mixed bacterial and fungal growth. i.e., total of 32 bacterial and 6 fungal isolates. Table 4 Correlation between the predisposing factors and microbial etiology Corneal trauma Vegetable matter induced Other trauma Contact lens induced Nontraumatic Post keratoplasty Bacterial cases 10 (33.3%) 13 (43.3%) - 5 (16.6%) 2 (6.6%) 30 Fungal cases 3(75 %) 1(25%) Total Here 23 out of 30(76.6%) bacterial cases were due to corneal trauma, 6.6% were post keratoplasty and 16.6% were non-traumatic. All the 4 cases of fungal ulcers were caused due to corneal trauma, of which (75%) were vegetable matter induced. 5) Bacterial pathogens causing corneal ulcers Table 5 Bacterial pathogens causing corneal ulcers Organism total no of isolates Staphylococcus species MSSA CONS MRSA 16 (50.0%) 6 (18.7%) 4 (12.5%) Pseudomonas aeroginosa 3 (9.3%) Klebsiella species 3(9.3%) B - 476

5 Figure 1 Bacterial organisms causing corneal ulcer Staphylococcus species (81.2%) was the most common organism isolated, of which 50% were Methicillin Sensitive Staphylococcus aureus (MSSA), 18.7% were Coagulase Negative Staphylococcus (CONS) and (12.5%) were Methicillin Resistant Staphylococcus aureus (MRSA). Pseudomonas aeroginosa and klebsiella sp were isolated from 3 cases each as in figure 1. 6 ) fungal pathogens causing corneal ulcers Table 6 shows fungal organisms causing corneal keratitis Organisms No of cases Aspergillus species Aspergillus niger 2(33.3%) Aspergillus fumigates 2(33.3%) Fusarium sp. 2(33.3%) Aspergillus niger, Aspergillus fumigatus and Fusarium species were isolated from 2 (33.3%) of fungal cases each. 7) Antibiotic sensitivity and resistant patterns. Table 7 Antibiotic sensitivity and resistant patterns Antibiotics (for gram+ve) MSSA (total 16) CONS (total 6) MRSA (total 4) No of sensitive No of resistant No of No of resistant No of No of resistant isolates isolates sensitive isolates sensitive isolates isolates isolates Penicillin 2(12.5%) 14(87.5%) 2(33.3%) 4(66.7%) 0 4 cotrimoxazole 4(25.0%) 12(75.0%) 4(66.7%) 2(33.3%) 0 4 Gentamycin 12(75.0%) 4(25.0%) 3(50%) 3(50%) 3(75%) 1(25%) Clindamycin 10(62.5%) 6(37.5%) 6 0 1(25%) 3(75%) Erythromycin 9(56.25%) 7(43.75%) 4(66.7%) 2(33.3%) 1(25%) 3(75%) Tetracycline 13(81.25%) 3(18.75%) Cefoxitin 12(75.0%) 4(25.0%) Cefuroxime 12(75.0%) 4(25.0%) Chloramphenicol 14(87.5%) 2(12.5%) 5(83.3%) 1(16.7%) 1(25%) 3(75%) Amoxiclav 14(87.5 %) 2(12.5%) Vancomycin 16(100%) Linezolid Oxacillin Ciprofloxacin 14(87.5%) 2(11.7%) 6 0 1(25%) 3(75%) B - 477

6 MSSA was found to be susceptible to gentamycin, cefoxitin and cefuroxime (75.0%), chloramphenicol and amoxiclav (87.5%) and vancomycin (100%). 12.5% were cefoxitin resistant (MRSA). These MRSA strains were sensitive to vancomycin, linezolid, gentamycin and tetracycline. Most of the staphylococcal isolates were resistant to penicillin (87.5%) and cotrimoxazole(75.0%). Only 12.5% of isolates were susceptible to penicillin as compared to vancomycin(100%) (p <0.001). Among the 2 isolates of P.aeroginosa, they were found to be resistant to most of the commonly used drugs and sensitive to imipenem, piperacillin and tazobactam. Treatment outcome most of the cases treated after identifying the susceptibility and resistant patterns did show considerable improvement. However, both the cases of pseudomonas perforated reflecting the high virulence of this organism. DISCUSSION We conducted this study to identify the predisposing factors, microbial etiology, the correlation between them and sensitivity and resistant patterns of the causative organisms to the commonly used antibiotics. In our study, corneal trauma was an overwhelming risk factor (65.4% cases). Similar results were seen in the study from south India which showed that corneal injury was responsible for 71.5 % cases of corneal ulcers [5]. Hyderabad study showed that 71.7 % of cases were due to corneal injury [8]. Our results are supported by a higher incidence of microbial keratitis following corneal injury in developing countries as mentioned earlier. This is in contrast to the studies from the developed countries which showed that contact lens wear as the (9). predominant predisposing risk factor However, in this study only a small percentage of cases (3.6 %) were due to contact lens wear. This difference is primarily due to differences in occupation, agriculture being the primary occupation in the developing countries especially India. In our study, we found that 60.0 % of patients were involved in agricultural practices % of patients were manual labourers. Both of these occupations are outdoor occupations, hence increasing the vulnerability to corneal injury. In contrast to this only 7.2 % and 9.1 % of cases were related to desk job and household activities respectively. In general, corneal ulcers are rare without predisposing risk factors, however in our study, it is interesting to note that 27.2 % of cases were non-traumatic and had no significant predisposing factors. Most of the non-traumatic cases were found in the age group of years, probably reflecting the exposure of young age group to external environment like increasing air pollution, U V radiation, chronic exposure to irritants especially in working places. The age groups above 50 years were particularly found to be susceptible to corneal trauma reflecting vulnerability to corneal injury in older people. About 3.6 % of cases were post kertoplasty and all cases were reported in patients above 60 years probably reflecting the impaired immune mechanisms of old age. In this study a significant male preponderance has been seen accounting for about 65.4 % cases of microbial keratitis. This figure is supported by the Hyderabad study [8] which showed that 70 % of cases were found in males. Positive cultures were seen in 36 cases (65.4%) which is similar to many other studies, such as those reported from Ghana [10] and Hyderabad which showed 60.4 % of positive cultures, but it is lower than the reports from Nepal [11] and from Bangladesh [12 ] which reported 80 % and 81.7 % of positive cultures. Bacterial keratitis were predominantly caused by gram positive bacteria, especially Staphylococcus sp. which included Methicillin Sensitive Staphylococcus aureus (MSSA), coagulase negative Staphylococcus aureus (CONS) and Methicillin Resistant Staphylococcus aureus (MRSA). However, unlike other studies from Asia [11], [4] and Africa [10] where infections by streptococcus B - 478

7 pnuemoniae were most common. A review of the literature showed that most of the studies from USA and Australia listed S. epidermidis or CONS as the leading cause of bacterial keratitis [13, 14]. These findings support our results. Considering the fact that staph. epidermidis forms the commonest commensal of the extra ocular surfaces, it is highly probable that these organisms invade corneal tissue when compromised by trauma or any other risk factor. Fungal isolates were seen in 11.1 % of cases which are relatively less when compared to other studies such as that reported from Madurai [4] and Hyderabad [8]. A study from West Bengal reported 38.1 % of fungal keratitis among the total microbial keratitis [15]. This might be due to the climatic differences where Bangalore has a milder climate and less humidity when compared to the coastal regions like Chennai and West Bengal. Aspergillus sp. and Fusarium sp. were predominant fungal organisms seen in our study. This result is supported by the study from South India [5] which implicated Fusarium sp. and Aspergillus sp. were major causative fungal organism. In this study the highest percentage of bacteria were susceptible to vancomycin (100%), ciprofloxacin and chloramphenicol (87.5%) and gentamycin (75.0%). In the Hyderabad study the highest percentage of gram positive isolates were susceptible to vancomycin (92.2%) followed by cefazolin (90.2%) and chloramphenicol (69.9%) [8]. The similar results were also seen in a study from Tamilnadu [5]. Only 12.5% of isolates were susceptible to penicillin as compared to vancomycin (100%) (p <0.001), reflecting almost complete resistance to penicillin by staph species. In our study the efficacy of ciprofloxacin against MSSA species was 87.5%, thus the results of this study show that monotherapy with ciprofloxacin for the initial empirical treatment of bacterial keratitis is a good option as it offers the advantage of commercial availability, broad spectrum activity and greater potency as compared to other drugs. However, Pseudomonas Sp. was resistant to most of the commonly used drugs and had a poor prognosis as both the cases showed perforation of the cornea. Hence, the study emphasizes on the initial antibiotic therapy for bacterial keratitis, which includes proper selection of a drug which has coverage for the aetiopathogen. CONCLUSION To conclude, the study highlighted that corneal injury was the principle risk factor for microbial keratitis and co-existing contact lens wear was not the significant cause in our setup. Fungal keratitis was more often associated with vegetable matter injury. It also reflected the male preponderance to corneal infections and increased vulnerability of older people to develop infective keratitis. The Study showed that Staphylococcus Sp. as the major cause for bacterial keratitis and Aspergillus and Fusarium Sp. for fungal keratitis. Among the bacterial pathogens, it showed the susceptibility patterns to drugs like vancomycin, ciprofloxacin, gentamycin and chloramphenicol. Overwhelming resistance was seen to penicillin and cotrimoxazole. ACKNOWLEDGEMENT We would like to thank ICMR (Indian council of medical research) for supporting this study and approving this study as a short term studentship study (ICMR-STS2012) REFERENCES 1. BourcierT, Thomas F, Bordeie, Chaumeil C. Bacterial keratitis: predisposing factors, clinical and microbiological review of 300 cases. Br J Ophthalmol 2003; 87(7): ) Whitcher JP, Srinivasan M, Upadhyay MP. Corneal blindness: a global B - 479

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