Household cockroaches carry CTX-M-15, OXA-48 and NDM-1, and share beta-lactam resistance determinants with humans

Aim. Household insect pests, including cockroaches, have gained consideration as potential vectors for multidrug resistant pathogens of public health concern. This study was designed to investigate whether household cockroaches share beta-lactam resistance determinants with human inhabitants. Methods. From February through July 2016, 400 cockroaches were systematically collected from 100 households. Whole insect homogenates and faecal samples from inhabitants of all included households were cultured for cephalosporin-resistant enterobacteria (CRe). The CRe were examined for AmpC, ESBL, and carbapenemase genes; antibiotic susceptibility patterns; and conjugative transfer of antibiotic resistance mechanisms. Clonal relationships between isolates were determined by multi-locus sequence typing (MLST). Results. Twenty CRe were recovered from whole cockroach homogenates of 15 households. Five harbored ESBL genes (2 blaCTX-M-15/TEM-1; 1 blaCTX-M-15/TEM-4; 1 blaTEM-24; 1 blaSHV-4), and 3 carried carbapenemase genes (2 blaNDM-1 genes and 1 blaOXA-48 gene)? all of which were transferrable by conjugation to E. coli J53 recipients. There was high clonal diversity with low inter-species similarity regardless of the beta-lactamase gene sequence. From 6 households, the pair of cockroach and human CRe shared the same antibiogram, ST and/or conjugable blaESBL gene sequence (house 34, E. coli ST9-blaTEM-4; house 37, E. coli ST44-blaCTX-15/TEM-4; house 41, E. coli ST443-blaCTX-15/TEM-1; house 49, K. pneumoniae ST231-blaSHV-13). Conclusion. The findings highlight household cockroaches as reservoirs of CTX-M-15, OXA-48 and NDM-1 genes that share beta-lactam resistance determinants with humans.