Etiology, drug resistance and disinfectant resistance of Yersinia pestis in Hainan, Qinghai Province / 中华地方病学杂志

ABSTRACT

Objective To investigate the etiology and the epidemiologic features of drug resistance and disinfectant resistance of Yersinia pestis in Hainan,Qinghai Province,in order to provide a scientific basis for prevention and control of the plague in this area.Methods Totally 75 strains were isolated from vary kinds of host in Hainan from 1960 to 2009,and biochemical test,virulence factors evaluation [Fra1 (F1),pesticin Ⅰ (Pst Ⅰ),virulence antigen (VW),pigmentation (Pgm)],plasmid analysis,different region (DFR) genotyping,drug resistance and disinfectant resistance gene test were carried out.Forty-five strains of Yersinia pestis were selected to determine their toxicity in mice,median lethal dose (LD50) was calculated,and LD50 ＜ 1 000 was defined as strongly toxic.Results Sixty of the 75 strains were Qing-Tibet Plateau ecotype,7 strains were Qilian Mountain ecotype,and the remaining 8 were different ecotypes from the plague foci in Qinghai Plateau.Eighty percent (60/75) contained all the four virulence factors;and 97.78％ (44/45) of the strains were velogenic strains;96.00％ (72/75) of the strains contained 3 kinds of plasmids (Mr6 × 106,45 × 106 and 52 × 106);the DFR strains had 3 genomovars,which were genomovar 8 (65 strains),genomovar 5 (8 strains) and genomovar 21 (2 strains).No strains related to streptomycin,sulfonamides,β-lactam antibiotics and disinfectants had been found in the 75 strains of Yersinia pestis.Conclusions The strains isolated in Hainan have the characteristics of Qinghai-Tibet Plateau plague's pathogen,and they have strong toxicity.In view of high mortality of plague,drug resistance and disinfectant resistance gene test should be put into routine monitoring of the plague.