Genetic diversity and molecular typing of Citrobacter in Maanshan, Anhui

Objective To understand the genetic and epidemiological relationship of Citrobacter strains isolated in Maanshan, Anhui province. Methods A total of 62 Citrobacter isolates were collected from diarrheal patients, foods and food processors in Maanshan from 2007 to 2011, including 13 C. fruendii strains, 41 C. youngae strains and 8 C. braakii strains. All the isolates were analyzed to understand their genetic diversity and molecular relationships by pulsed field gel electrophoresis (PFGE) with Xba Ⅰ and multi-locus sequence typing (MLST) for 7 housekeeping genes. Results PFGE divided the 62 Citrobacter isolates into 43 pulse types (PTs) and MLST divided them into 53 sequence types (STs). By PFGE, CITX01.CN0039 was predominant PT, which consisted of 7 C. youngae strains isolated from foods and diarrheal patients between 2007 and 2008. Related STs in 53 STs were divided into 5 ST complexes, and ST complex 39 included isolates from diarrheal patient, food processors and foods. Isolates from diarrheal patients shared the same PTs and STs with those from foods and food processors. Conclusion Surveillance for Citrobacter is important for the prevention and control of diarrheal infections caused by Citrobacter.