The May 2012 Shigella outbreak traced to a private bridge club in California’s Los Angeles county was found to be the first involving Shigella bacteria with a decreased susceptibility to azithromycin, an antibiotic that is usually effective against multi-drug-resistant Shigella, the U.S. Centers for Disease Control and Prevention reported last week. Cases of shigellosis with lowered susceptibility to azithromycin have appeared sporadically in the U.S., but this was the first documented outbreak. Outbreak samples submitted to the CDC also showed resistance to streptomycin, sulfisoxazole, tetracycline and trimethoprim-sulfamethoxazole. Patients were found to have visited or worked at the bridge club between May 22 and 26, 2012, with ages ranging from 54 to 98 years old. County health investigators ultimately found 39 shigellosis cases among visitors, along with two workers who experienced symptoms such as diarrhea, and an additional two infected workers who did not show symptoms. Thirty-one sought medical care and 10 were hospitalized. Investigators did not find a specific outbreak source. PulseNet, a nationwide epidemiology network, identified two additional Shigella isolates genetically indistinguishable from the outbreak strain: one from a Pennsylvania man who visited L.A. in April, and another from a Hawaii man who visited L.A. during April and May. Neither of these patients had a connection to the bridge club.
