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Abstract
Purpose
To analyze clinical aspects in a cohort of patients with Staphylococcus keratitis according to coagulase positivity (coagulase negative Staphylococcus [CNS], coagulase positive Staphylococcus [CPS]).
Methods
Epidemiology, predisposing factors, clinical characteristics, treatment outcomes, and antibiotic susceptibility were comparatively analyzed in 138 cases of culture-proven Staphylococcus keratitis (94 eyes with CNS and 44 eyes with CPS) over 20 years (1998–2017) at Yeungnam University Hospital. Poor clinical outcomes were defined as a final corrected visual acuity <0.1, a decreased visual acuity after treatment, complications, or surgical treatment. Risk factors for poor clinical outcomes were evaluated in the total cohort and analyzed using multivariate logistic regression.
Results
The most common predisposing factors were corneal trauma in the CNS group (47.9%) and previous ocular surface disease in the CPS group (31.8%). No significant differences were observed in mean age, sex, previous ocular surface disease, epithelial defect size, and hypopyon between the two groups. Methicillin susceptibility (39.4% vs. 72.7%, p < 0.001) was significantly lower in the CNS group, and poor clinical outcomes (28.0% vs. 43.9%, p = 0.076) were more common in the CPS group. The significant risk factors for poor clinical outcomes were initial best-corrected visual acuity <0.1, epithelial defect size ≥ 5 mm2, symptom duration ≥10 days, and hypopyon.
Conclusions
No significant differences were observed in epidemiological factors and initial clinical characteristics between the two study groups, but predisposing factors and methicillin susceptibility differed between the two groups. Treatment outcomes were relatively worse in the CPS group than in the CNS group, but the difference was not statistically significant. Poor clinical outcomes were more associated with long symptom duration and poor initial clinical characteristics than with coagulase positivity.
Figures and Tables
Figure 1
Frequency of Staphylococcus keratitis* according to coagulase positivity during 1998-2017. CNS = coagulase negative Staphylococcus; CPS = coagulase positive Staphylococcus; S = Staphylococcus; K = Klebsiella; P = Pseudomonas; E = Enterobacter; A = Acinetobacter; spp. = species. *Total (n = 138); 9 cases had mixed infection (CNS 5 cases, CPS 4 cases): S. epidermidis, K. oxytoca, P. aeruginosa; S. epidermidis, Enterococcus faecalis; S. epidermidis, E. aerogenes; S. epidermidis, P. aeruginosa; S. epidermidis, A. baumannii; S. aureus, E. cloacae, Candida spp.; S. aureus, P. aeruginosa; S. aureus, Enterococcus faecalis; S. aureus, E. cloacae.
Table 2
Predisposing factors of Staphylococcus keratitis according to coagulase positivity
Values indicate numbers (proportion).
CNS = coagulase negative Staphylococcus; CPS = coagulase positive Staphylococcus; DM = diabetes mellitus.
*Total numbers can be greater than 100% because of some patients with multiple predisposing factors; †chi-square test; ‡Fisher's exact test; §Recurrent corneal erosion (CNS 2 cases and CPS 2 cases), bullous keratopathy (CNS 2 cases and CPS 2 cases), exposure keratitis (CNS 3 cases and CPS 2 cases), pterygium (CPS 1 case), atopic keratoconjunctivitis (CNS 1 case), and Mooren ulcer (CNS 1 case).
Table 3
Clinical characteristics and treatment outcomes of staphylococcal keratitis according to cofagulase positivity
Values indicate numbers (proportion) unless otherwise noted.
CNS = coagulase negative staphylococcus; CPS = coagulase positive staphylococcus; PED = persistent epithelial defect; BCVA = best corrected visual acuity; AMT = amniotic membrane transplantation; PKP = penetrating keratoplasty.
*Central lesion is located within 1/2 radius from the center of the cornea; †chi-square test; ‡total (n = 134); 3 cases of children (CNS 1 case and CPS 2 cases) who could not read letters and 1 case of missing record in the CPS were excluded; §total (n = 111); 23 cases who were surgically treated, 3 cases of children (CNS 1 case and CPS 2 cases) who could not read letters, and 1 case of missing record in the CPS group were excluded; ΠFisher's exact test; #the clinical outcomes were assessed at the final visit or at completion of treatment and classified into two groups by modifying the criteria defined by Green et al.7
Table 5
Risk factors for poor clinical outcomes* in the total cohort of patients with Staphylococcus keratitis† (univariate and multivariate logistic regression analysis‡)
OR = odds ratio; CI = confidence interval; CNS = coagulase negative Staphylococcus; CPS = coagulase positive Staphylococcus; OSD = ocular surface disease; BCVA = best corrected visual acuity.
*The clinical outcomes were assessed at the final visit or at completion of treatment and classified into two groups by modifying the criteria defined by Green et al.7; †total (n = 134), 3 cases of children (CNS 1 case and CPS 2 cases) who could not read letters and 1 case of missing record in the CPS were excluded; ‡multivariate logistic regression analysis was performed using the backward-conditional method for the factors with a p-value < 0.1 in univariate logistic regression analysis; §logistic regression analysis.
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