Impact of Non-culture Based Testing Methods on Campylobacter Surveillance in New Mexico

Campylobacter is one of the top five pathogens responsible for domestically acquired foodborne illness in the United States. Active surveillance estimates 13 cases per 100,000 persons are diagnosed annually, with 15% resulting in hospitalization. Diagnosis of Campylobacter is currently based on the isolation of the organism from a stool specimen, using a specialized medium incubated at 42°C for several days. Non-culture based methods, utilizing the detection of Campylobacter antigen directly from stool, are less labor intensive, and results are available more quickly than from cultures. The introduction of non-culture based methods by clinical labs has begun to have an impact on Campylobacter laboratory testing and public health surveillance in New Mexico. In 2009, Campylobacter was identified by non-culture methods in seven stool specimens by one clinical lab. All seven cases were later excluded as surveillance cases, as culture confirmation by the state public health laboratory (SPHL) is required and the specimens were not submitted by the clinical lab to the SPHL. In 2010, 93 specimens were identified as Campylobacter species using non-culture methods from six clinical labs. Fifty-two specimens, as preserved raw stool, were sent to the SPHL for confirmation by culture-based methods. Twenty-seven of these specimens (52%) did not grow Campylobacter and 25 specimens (48%) generated Campylobacter isolates which were speciated as C. jejuni or C. coli. The isolation of Campylobacter by culture is required to meet “confirmed” case definition in laboratory-based surveillance. Movement away from culture-based methods directly impacts how states define and monitor enteric infections.