Rk. Olson et al., Cluster of postinjection abscesses related to corticosteroid injections and use of benzalkonium chloride, WEST J MED, 170(3), 1999, pp. 143-147
Benzalkonium chloride (BC) is an unreliable disinfectant. A matched case-co
ntrol study and environmental investigation were conducted to determine the
cause of and risk factors for a cluster of postinjection abscesses at a pr
ivate medical clinic where BC was used as a disinfectant. Twenty-eight case
-patients who had an abscess at the injection site were matched with 126 co
ntrol patients who had received an intramuscular injection at the clinic on
the same day. Risk factors for abscess development in a multivariable logi
stic model were corticosteroid injection and being female. All case-patient
s had received a corticosteroid injection from a multidose vial. Cultures o
f abscesses from 20 of 23 case-patients grew Pseudomonas aeruginosa. Cultur
es of BC prepared at the clinic also grew P aeruginosa, suggesting that BC
was the source of infection. Injection site cleaning with BC did not appear
to be the route of infection since use of BC at the time of injection was
not associated with abscess development. A more likely route of infection w
as injection of contaminated corticosteroid from multidose vials that could
have been inoculated with pseudomonads via needle puncture after vial sept
a were wiped with contaminated BC. Benzalkonium chloride should not be used
to clean injection vial septa or injection sites.