Results
Patient Characteristics
Between 2006 and 2011, 41 corneal samples from 41 children with infectious keratitis were identified. Twenty-one cases were male (51%), and 20 were female (49%). The mean patient age was 8.7 years ± 5.1 (range, 3 months to 15 years). The mean time from the onset of symptoms to the ophthalmological examination was 12.7 days ± 18.7 (range, 1–60 days).
Predisposing factors were identified in 78% of cases, with 2 or more factors occurring in 26%. The most common predisposing factor was ocular trauma (25%), followed by wearing contact lenses and prolonged steroid treatment (Table 1). In cases associated with ocular trauma, pencils were the most common cause (10.6%); other was associated with fireworks, cat scratch, rope, soil and toys.
Patients with CDVA ≥ 20/60 at admission showed a statistically non-significant improvement of their vision at discharge, but happened inversely when CDVA was < 20/60 (p=0.003). A worsening of visual acuity was more pronounced when CDVA was less than 20/200 at admission (mean increment of logMar 1.04, p = 0.002). Linear regression analysis showed for lower visual acuity at admission, lower visual acuity at discharge (p<0.0001) [Figure 1].
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Figure 1.
Linear regression model:Estimation of change of visual acuity at discharge for every unit of visual acuity at admission. Legend: An mean increment of logMAR 0.55 at discharge was observed for every increasing unit of logMAR at admission, p <0.0001
The ophthalmological examination revealed a mean epithelial defect size of 2.74 ± 1.6 mm, with visual axis involvement in 63.2% of cases, anterior chamber reaction in 31.6% and hypopyon in 15.8%.
Treatment
As mentioned previously initial medical therapy was based on fourth generation fluoroquinolones and modified according to clinical response or antibiogram. In 26 patients (63.4%) this therapeutic regimen remained (0.5% moxifloxacin or 0.3% gatifloxacin); 6 (14.6%) were switched to macrolides (0.5% erythromycin); 5 (12.2%) to third generation cephalosporins (5% ceftazidime); 3 (7.3%) to third generation fluoroquinolones (0.3% ciprofloxacin) and 1 (2,4%) to topical 0.15% amphotericin B together with 1% natamycin and systemic oral itraconazole.
Medical therapy achieved remission in 39 cases (95%). One case developed endophthalmitis and was successfully treated with intravitreal antibiotics (vancomycin and ceftazidime). Perforation occurred in a single case and was treated with tectonic keratoplasty.
Microbiology
Regarding the microbiological results, 66% (n=27) were negative, 26% of them (n=7) were previously treated with topical antibiotics. Cultures were positive in only 34% (n= 14), which identified 7 different microorganisms and no polymicrobial infections. Bacteria were responsible for infection in 93% (13) and fungi (Microsporum gypseum) in 7% (n=1).
Gram-positive bacteria were isolated in 79% (n=11) of the positive cultures. Staphylococcus epidermidis was the most common isolate followed by equal frequencies of Streptococcus spp.,Corynebacterium spp. and Pseudomonas aeruginosa. No significant association between risk factors and culture positivity was encountered (Table 2).
The antibiogram of Staphylococcus spp. isolates revealed that all isolates were sensitive to gentamicin, 80% (n=4) were sensitive to vancomycin and ciprofloxacin. Eighty percent (n=4) of these demonstrated resistance to sulfamethoxazole, and 75% (n=3) to cefazolin, oxacillin and polymyxin B. Eighty percent (n=4) of these revealed resistance to multiple antibiotics.
All Streptococcus spp. isolates were sensitive to ciprofloxacin, cefazolin, ofloxacin and ceftriaxone, while 75% (n=3) were also sensitive to sulfamethoxazole, vancomycin and gentamicin. Seventy five percent (n=3) were resistant to polymyxin B.
Both Pseudomonas aeruginosa isolates were sensitive to gentamicin and resistant to ciprofloxacin and ceftazidime.