The risk of agricultural predominance and vegetative corneal injury in fungal keratitis and associated ocular diseases in bacterial keratitis increase susceptibility to corneal infection. A hot, windy climate makes fungal keratitis more frequent in tropical zones, whereas bacterial keratitis is independent of seasonal variation and frequent in temperate zones. Microbial pathogens show geographical variation in their prevalence. Thus, the spectrum of microbial keratitis varies with geographical location influenced by the local climate and occupational risk factors.

Aims: To determine the sensitivity, specificity and predictive values of potassium hydroxide (KOH) wet mount, Gram stain, Giemsa stain and Kinyoun's acid-fast stain in the diagnosis of infective keratitis. Methods: A retrospective analysis of all patients with clinically diagnosed infective keratitis presenting between September 1999 and September 2002 was carried out. Corneal scrapes were taken and subjected to direct microscopy and culture. Results: 3298 eyes of 3295 consecutive patients with infective keratitis were evaluated, of which 1138 (34.51%) eyes had fungal growth alone, 1069 (32.41%) had bacterial growth alone, 33 (1%) had Acanthamoeba growth alone, 83 (2.5%) had mixed microbial growth and the remaining 975 (29.56%) had no growth. The sensitivity of KOH wet mount was higher (99.3%; 95% confidence interval (CI) 98.6 to 99.6) in the detection of fungi, 100% (95% CI 90.4 to 100) in the detection of Nocardia and 91.4% (95% CI 75.8 to 97) in the detection of Acanthamoeba) than that of Gram-stained smears (89.2% (95% CI 87.3 to 90.8) in fungi, 87% (95% CI 73.0 to 94.6) in Nocardia and 60% (95% CI 42.2 to 75.6) in the detection of Acanthamoeba) in the detection of fungi, Nocardia and Acanthamoeba. 1764 of 3295 (53.54%) patients presented more than 7 days after onset of illness and 84.69% of the eyes had corneal ulcers with size .2 mm in diameter. Positivities of KOH (44.46%; p,0.001) and Gram-stained smears (77.37%; p,0.001) were found to be higher among eyes with larger ulcers (.2 mm) than among eyes with smaller ulcers (,2 mm). Conclusion: KOH smear is of greater diagnostic value in the management of infective keratitis, and it is recommended in all clinics without exception for establishing timely treatment.

Aims:To identify the etiology, incidence and prevalence of ocular bacterial infections, and to assess the in vitro susceptibility of these ocular bacterial isolates to commonly used antibiotics.Materials and Methods:Retrospective analysis of consecutive samples submitted for microbiological evaluation from patients who were clinically diagnosed with ocular infections and were treated at a tertiary eye care referral center in South India between January 2002 and December 2007.Results:A total of 4417 ocular samples was submitted for microbiological evaluation, of which 2599 (58.8%) had bacterial growth, 456 (10.3%) had fungal growth, 15 (0.34%) had acanthamoebic growth, 14 (0.32%) had mixed microbial growth and the remaining 1333 (30.2%) had negative growth. The rate of culture-positivity was found to be 88% (P < 0.001) in eyelids’ infection, 70% in conjunctival, 69% in lacrimal apparatus, 67.4% in corneal, 51.6% in intraocular tissues, 42.9% in orbital and 39.2% in scleral infections. The most common bacterial species isolated were Staphylococcus aureus (26.69%) followed by Streptococcus pneumoniae (22.14%). Sta. aureus was more prevalent more in eyelid infections (51.22%; P = 0.001) coagulase-negative staphylococci in endophthalmitis (53.1%; P = 0.001), Str. pneumoniae in lacrimal apparatus and corneal infections (64.19%; P = 0.001), Corynebacterium species in blepharitis and conjunctivitis (71%; P = 0.001), Pseudomonas aeruginosa in keratitis and dacryocystitis (66.5%; P = 0.001), Haemophilus species in dacryocystitis and conjunctivitis (66.7%; P = 0.001), Moraxella lacunata in blepharitis (54.17%; P = 0.001) and Moraxella catarrhalis in dacryocystitis (63.83%; P = 0.001). The largest number of gram-positive isolates was susceptible to moxifloxacin (98.7%) and vancomycin (97.9%), and gram-negative isolates to amikacin (93.5%) and gatifloxacin (92.7%).Conclusions:Gram-positive cocci were the most frequent bacteria isolated from ocular infections and were sensitive to moxifloxacin and vancomycin, while gram-negative isolates were more sensitive to amikacin and gatifloxacin.

Purpose To identify the microbial aetiology of infectious endophthalmitis and to determine the in vitro antibacterial susceptibilities of bacterial isolates. Methods A retrospective analysis was carried out of all patients presenting between January 1997 and December 2006 with clinically diagnosed infectious endophthalmitis who underwent microbiological evaluation. Intraocular specimens (aqueous and vitreous fluids) were collected from all cases of clinically suspected infectious endophthalmitis. In addition to intraocular aspirates, blood specimens from endogenous endophthalmitis, and corneal and scleral scrapes from relevant cases were also collected. The collected intraocular specimens, blood specimens, and corneal and scleral scrapes were subjected to microbiological evaluation. Results Samples from 955 patients with endophthalmitis underwent microbiological analysis, of which 424 (44.4%) were found to be culture positive. Of 424, 364 (85.8%) had bacterial growth and the remaining 60 (14.2%) had fungal growth. Among post-surgical endophthalmitis, Gram-negative bacilli (75%) were found to be the predominant cause for developing fulminant onset, Staphylococcus spp. (68.6%) for acute, and Streptococcus spp. (75%) for chronic onset of infections, whereas in post-traumatic endophthalmitis, Gramnegative bacilli (65.2%) were found to be the predominant cause for fulminant onset, Gram-positive bacillus (28.4%) for acute onset, and fungi (52.3%) for chronic onset of infections. Endophthalmitis associated with microbial keratitis was mainly caused by filamentous fungi (37.2%) and Gram-negative bacilli (37.2%). Overall, gatifloxacin (97.7%) showed highest activity against bacterial isolates followed by ciprofloxacin (95.9%) and ofloxacin (95.1%). Conclusion Gram-negative bacilli cause predominantly fulminant onset, Staphylococci and Gram-positive bacilli acute, and Streptococci, Nocardia, and fungi chronic endophthalmitis. Gatifloxacin demonstrated greatest efficacy against these bacterial isolates.

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Although P. aeruginosa corneal ulcers have a more severe presentation, they appear to respond better to treatment than other bacterial ulcers. The authors did not find a significant benefit with corticosteroid treatment, but they also did not find any increase in adverse events. (ClinicalTrials.gov number, NCT00324168.).

NCT00324168.