Purpose
To report the risk factors and microbiological profile of pediatric microbial keratitis cases in a tertiary care hospital in Hong Kong.
Design
Retrospective study.
Methods
Case records of patients <18 years old with microbial keratitis were reviewed over a period of 10 years, between January 2001 and December 2010. Risk factors, microbiological profile, and treatment outcomes were analyzed.
Results
Overall, 18 patients (13 female, 5 male) with unilateral microbial keratitis were included. The mean age was 12.4 years (range: 3-17 years). The most commonly associated risk factor was contact lens wear (15, 83.3%). Seven cases (38.8%) were associated with orthokeratology lenses. Two cases (11.1%) were related to intrinsic keratopathy and 1 case (5.5%) was infected secondary to trauma. Microbiological culture was positive in 16 cases (88.8%). Overall, Pseudomonas sp. was the most commonly isolated organism (10/16, 62.5%), followed by coagulase-negative Staphylococcus (5/16, 31.2%) and Corynebacterium sp. (2/16, 12.5%). All cases responded to intensive medical management with topical antibiotics. One case with posttraumatic keratitis required stepped surgeries with initial tectonic penetrating keratoplasty followed by lens aspiration and retinal detachment repair. At the last follow-up, 13 out of 17 eyes (76.5%) had best-corrected visual acuity ≥20/40.
Conclusions
Contact lens wear was the most commonly encountered risk factor for the occurrence of microbial keratitis in the pediatric age group in our setting. Orthokeratology remains one of the leading causes of contact lens–related infections. The majority of the cases responded to medical management.)
Microbial keratitis is an important cause of ocular morbidity in both the developing and the developed world. Early diagnosis and management is vital in order to prevent permanent visual loss. This is more pertinent in the pediatric age group, where detection and treatment of microbial keratitis poses a bigger challenge as compared to the adult population. Risk factors associated with the occurrence of microbial keratitis in the pediatric age group also follow a geographic pattern. Whereas trauma is a major risk factor in developing countries, contact lens wear has been shown to be a predominant risk factor in the industrialized parts of the world. In terms of the causative agents, both gram-positive and gram-negative bacteria have been identified in pediatric keratitis. Studies from Oman and northern India reported isolation of predominantly gram-positive organisms from pediatric keratitis cases. Another study from Florida found gram-negative bacilli to be prevalent in pediatric keratitis. Fungal infections constituted approximately one-third of all pediatric keratitis cases in a report from southern India.
In the present study, we analyzed the risk factors, microbiological profile, and treatment outcomes of cases of microbial keratitis in the pediatric age group.
Methods
A retrospective chart review was conducted for pediatric patients with microbial keratitis (nonviral) presenting to the Prince of Wales Hospital, Hong Kong between January 2001 and December 2010. The Institutional Review Board of the hospital (New Territories Ethics Committee) approved the study protocol. The study adhered to the tenets of the Declaration of Helsinki. Case numbers were obtained from the Department of Microbiology of the same hospital. Case records of patients <18 years old who had presented with microbial keratitis to the outpatient department of the hospital during the study period were analyzed. The inclusion criteria included a clinical diagnosis of microbial (nonviral) keratitis based on the presence of an epithelial defect with stromal infiltrate. The medical records were reviewed for associated risk factors, microbiological profile, pre- and posttreatment visual acuity, treatment modalities, and the final outcomes.
A detailed clinical history was obtained. Slit-lamp examination was performed to evaluate the anterior and posterior segments of the eye. Visual acuity was measured using a Snellen chart whenever possible. Corneal scrapings were obtained from all the cases and submitted for Gram staining and potassium hydroxide wet mount. In addition, the specimens obtained were inoculated onto blood agar, chocolate agar, and Sabouraud dextrose agar. Microbiological cultures were performed on non-nutrient agar for detection of Acanthamoeba in patients with a history of contact lens use. Intensive topical antimicrobial therapy was started while awaiting the microbiological results. Subsequent modifications in the choice and dosage of antibiotics were made according to the culture results, sensitivity pattern, and clinical response.
Results
Overall, 18 patients (13 female, 5 male) were included. The mean age was 12.4 years (range: 3-17 years). All patients had unilateral ocular involvement (9 right eyes, 9 left eyes). The most commonly associated risk factor was contact lens wear, identified in 15 cases (83.3%). Seven cases (38.8%) were associated with orthokeratology lens overnight wear. Two cases (11.1%) were related to intrinsic keratopathy (1 vernal keratoconjunctivitis, 1 exposure keratopathy). Only 1 patient (5.5%) had infectious keratitis secondary to trauma ( Table ).
| Age/Sex | Risk Factors | Microbiological Culture | Visual Acuity at Presentation | Final Best-Corrected Visual Acuity | Final Outcome |
|---|---|---|---|---|---|
| 13/F | Orthokeratology lenses | Pseudomonas aeruginosa | NA | 20/70 | Paracentral scar |
| 14/F | Extended-wear contact lenses | Pseudomonas aeruginosa Coagulase-negative Staphylococcus | 20/50 | 20/50 | Peripheral scar |
| 10/F | Orthokeratology lenses | Pseudomonas aeruginosa | 20/100 | 20/30 | Central scar |
| 13/M | Orthokeratology lenses | Pseudomonas aeruginosa Coagulase-negative Staphylococcus | HM | 20/25 | Central scar |
| 17/F | Monthly contact lenses | Pseudomonas aeruginosa | 20/400 | 20/35 | Paraxial scar (using RGP) |
| 14/M | Daily-wear contact lenses | Pseudomonas aeruginosa | 20/40 | 20/15 | Peripheral scar |
| 14/M | Orthokeratology lenses | Pseudomonas aeruginosa | HM | 20/25 | Central scar |
| 10/M | Vernal keratoconjunctivitis | Corynebacterium sp | 20/20 | 20/15 | Paracentral scar |
| 11/F | Orthokeratology lenses | None | 20/400 | 20/20 | Central scar |
| 14/F | Biweekly disposable contact lenses | Pseudomonas aeruginosa | HM | 20/100 | Central scar (operated DALK) |
| 11/M | Orthokeratology lenses | Pseudomonas aeruginosa | 20/200 | 20/30 | Paracentral scar |
| 14/F | Orthokeratology lenses | Coagulase-negative Staphylococcus | HM | 20/20 | using RGP |
| 3/F | Exposure keratopathy attributable to necrotizing encephalopathy | Corynebacterium sp | NA | NA | No follow-up |
| 13/F | Biweekly disposable contact lenses | Pseudomonas aeruginosa | 20/100 | 20/20 | Paraxial scar |
| 15/F | Colored contact lenses | Coagulase-negative Staphylococcus | 20/15 | 20/10 | Clear cornea |
| 16/F | Monthly contact lenses | None | 20/15 | 20/15 | Clear cornea |
| 5/F | Corneal laceration | Staphylococcus aureus | NA | CF | Multiple surgeries |
| 16/F | Monthly contact lenses | Pseudomonas aeruginosa | NA | 20/10 | Small central scar |
Six out of 18 cases (33.3%) were positive for microbial cells upon microscopic investigation (5 gram-negative bacilli, 1 gram-positive cocci). Microbiological culture was positive in a majority of the cases (16/18, 88.8%). On microbiological culture, 14 cases had a single pathogen identified and 2 cases had a co-infection. The co-infection in 2 cases was attributable to Pseudomonas and coagulase-negative staphylococci secondary to the use of extended-wear contact lenses and orthokeratology lenses ( Table ). Overall, Pseudomonas sp. was the most commonly isolated organism (10/16, 62.5%), followed by coagulase-negative staphylococci (5/16, 31.2%) and Corynebacterium sp. (2/16, 12.5%). All Pseudomonas infections were related to contact lens wear.
Fourteen of 18 cases (77.7%) were treated with fortified antibiotics and 4 (4/18, 22.3%) were treated with intensive topical levofloxacin 0.3% eye drops. A combination of ceftazidime (50 mg/mL) and tobramycin (14 mg/mL) were used alternately every half-hour in 13 eyes. Additionally, hourly 0.3% ofloxacin ointment was used in 5 cases. Overall 17 of 18 cases (94.4%) responded to medical management alone. One case secondary to trauma required multiple surgeries with initial tectonic penetrating keratoplasty followed by lens aspiration and retinal detachment repair.
At the last follow-up, 13 out of 17 eyes (76.5%) had a best-corrected visual acuity (BCVA) of ≥20/40, 3 (17.6%) had BCVA between 20/50 and 20/100, and 1 (5.9%) had BCVA <20/200. Corneal scarring was documented in 13 cases (76.4%) after treatment. One patient required optical deep anterior lamellar keratoplasty and postoperatively achieved a BCVA of 20/20 with rigid gas-permeable contact lens.
Results
Overall, 18 patients (13 female, 5 male) were included. The mean age was 12.4 years (range: 3-17 years). All patients had unilateral ocular involvement (9 right eyes, 9 left eyes). The most commonly associated risk factor was contact lens wear, identified in 15 cases (83.3%). Seven cases (38.8%) were associated with orthokeratology lens overnight wear. Two cases (11.1%) were related to intrinsic keratopathy (1 vernal keratoconjunctivitis, 1 exposure keratopathy). Only 1 patient (5.5%) had infectious keratitis secondary to trauma ( Table ).
