[Laboratory-based characterization and traceability of an outbreak of necrotising enterocolitis]

Objective: Laboratory-based characterization and traceability were performed on an outbreak of necrotising enterocolitis (NEC) happened in a maternal and child health care hospital in China. Methods: Thirty-seven samples were collected from 3 NEC cases, that the clinical manifestations was bloody stools. Clostridium spp. isolation and identification were carried out on stool, breast milk, milk-based infant powder and environmental swab samples collected during NEC outbreak from October to November in 2016. Meanwhile, twenty-four swabs samples from ward environmental, staffs' hand as well as articles for neonates daily use were also collected and tested for Clostridium spp. after disinfection following outbreak. Pulsed-field gel electrophoresis (PFGE) analysis was performed on all Clostridium strains obtained. Results: 46% (17/37) samples were positive for a presumptive Clostridium spp. during the outbreak of NEC. One type of Clostridium spp. isolates was cultured from 10 samples including the hands of medical staffs, some medical equipments in the ward and milk-based infant powder ingested by the case, it was identified as C.butyricum. Another type of Clostridium spp. isolates was cultured from 2 samples including breast milk and inner wall of breast milk fresh-keeping bag, it was identified as C.sporogens. Both of these two types isolates were cultured from 5 samples including inner wall of breast milk box, inner wall of refrigerator, the handle of case's incubator and the case's stool. PFGE analysis showed that all 15 strains of C. butyricum and 7 strains of C.sporogens isolated from the samples mentioned above produced indistinguishable pulsotypes respectively. No NEC cases were found after disinfection following the outbreak and all samples collected after outbreak were negative for Clostridium spp. Conclusion: The outbreak of NEC was highly related to C. butyricum contamination within the hospital.