Microbial patterns and culture utility in orbital cellulitis

Abstract

Purpose: To determine the prevalence and types of pathogens found in children with orbital cellulitis and to evaluate the utility of nonoperative cultures.

Methods: This was a retrospective cohort study of children with imaging-confirmed orbital cellulitis over a period of 8 years. Outcomes included prevalence and types of organisms, polymicrobial infection, mixed aerobic-anaerobic infection, effect of age, and culture utility.

Results: Of 220 children with orbital cellulitis, 112 (51%) had cultures taken; 69 (31%) had surgical intervention. Culture sources for the 112 children with cultures included blood (57 patients [51%]), sinus (53 [47%]), orbit (42 [38%]), brain (6 [5%]), and skin/conjunctiva/lacrimal sac (6 [5%]). Streptococcus anginosus group strains grew in cultures from 19 children (17%); methicillin-sensitive Staphylococcus aureus (MSSA), in 15 (13%); Streptococcus pyogenes, in 12 (11%); methicillin-resistant Staphylococcus aureus (MRSA), in 6 (5%); anaerobic/facultative gram negative rods, in 8 (7%); anaerobic Gram-positive cocci, other Viridans group streptococci, and Streptococci pneumoniae, in 3 (3%) each; and normal respiratory/skin flora, in 23 (21%). Polymicrobial infection (P = 0.08) and anaerobic organisms (P = 0.58) did not differ by age (range, 0.1-16.8 years). In all 220 (100%) children, nonoperative cultures were either not obtained (108 [49%]), not helpful in avoiding surgery (69 [31%]), showed no growth (39 [18%]), or grew an organism that did not change management from empiric therapy (4 [2%]).

Conclusions: While many organisms may be cultured from children with orbital cellulitis, Streptococcus and MSSA were the most common in our study cohort. MRSA is uncommon, so initial empiric coverage is not necessary. Rates of polymicrobial and anaerobic infection were similar across ages. Our results indicate that nonoperative cultures are not indicated in the initial medical management of orbital cellulitis; in our cohort, they neither resulted in treatment changes nor helped avoid surgery.