An outbreak of conjunctivitis due to a novel unencapsulated Streptococcus pneumoniae among military trainees.
BACKGROUND
Bacterial conjunctivitis usually occurs as sporadic cases; outbreaks are uncommon and usually are associated with school campuses. We report an outbreak of Streptococcus pneumoniae conjunctivitis at a military training facility.


METHODS
An outbreak investigation was done. Each case of conjunctivitis was evaluated with an assessment tool including demographic and clinical data. Conjunctival swabs were obtained. Pneumococci underwent standard testing, including serotyping with the Quellung reaction, capsular staining, and multilocus sequence typing. Sequence types were compared with previous reported outbreak strains by construction of dendrograms. Carriage rates of S. pneumoniae were determined among previously undiagnosed case patients with conjunctivitis, and a case-control study was performed. Control measures included education to increase hand washing, distribution of alcohol-based hand gel, and prompt treatment of patients with conjunctivitis.


RESULTS
During a 6-week period, 92 cases of conjunctivitis occurred among 3500 persons, with an attack rate of 1.75 cases per 100 person-months. Eighty cases (87%) were due to S. pneumoniae; 45 (49%) were confirmed, and 35 (38%) were probable. Ten percent of recruits surveyed carried the outbreak strain. Twenty-two percent self-reported symptoms consistent with conjunctivitis during the outbreak period; sharing washcloths was associated with conjunctivitis (odds ratio, 11.7; P=.03). The causative organism was resistant to azithromycin but susceptible to telithromycin. The outbreak strain was an unencapsulated S. pneumoniae that has not been previously described; it was most closely related to the sequence type causing the Dartmouth College (Hanover, NH) outbreak of conjunctivitis in 2002.


CONCLUSIONS
We report a conjunctivitis outbreak among military trainees caused by a novel, unencapsulated strain of S. pneumoniae.
Clinical Investigation Department, Naval Medical Center San Diego, San Diego, CA 92134-1005, USA. nfcrum@nmcsd.med.navy.mil
Nancy F
NF
Crum
Christopher P
CP
Barrozo
Frank A
FA
Chapman
Margaret A K
MA
Ryan
Kevin L
KL
Russell
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003234:Conjunctivitis, Bacterial / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D006801:Humans; D008889:Military Personnel; D016017:Odds Ratio; D010802:Phylogeny; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D012307:Risk Factors; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents