Effect of temperature and antimicrobial resistance on survival of Campylobacter jejuni in well water: application of the Weibull model

Abstract

The aims of this study were to measure the survival of two Campylobacter jejuni strains and their in vitro-challenged antimicrobial-resistant variants in well water, to evaluate the effects of antimicrobial resistance on survival and to develop a mathematical model for predicting the survival of Camp. jejuni in well water in the temperature range from 4 to 25°C. The survival in log CFU ml⁻¹ of two Camp. jejuni strains and their antimicrobial-resistant variants was studied in well water stored at 4, 10, 15, 20 and 25°C. At 4°C, the estimated 4-log CFU ml⁻¹ decrease in ciprofloxacin-resistant variant ATCC33560CIP32 was 55·2 days, significantly longer (P < 0·05) than that of resistant variant 49/7RATCIP32 (the estimated 4-log CFU ml⁻¹ decrease was 29·9 days). The respective times for the wild-type strains were 49·8 and 60·4 days. The decrease in counts of Camp. jejuni was most dependent on temperature, because at 4°C, the estimated t (4D) varied from 29·9 to 60·4 days and at 25°C from 3·7 to 5·7 days. Campylobacter jejuni survived in well water for long periods, especially at 4°C, and the effect of ciprofloxacin resistance on fitness and survival was strain and temperature dependent. Weibull model was found to fit the data in the temperatures from 4 to 25°C. In water environment Camp. jejuni is exposed to a wide spectrum of temperatures, which affects its survival and potential to cause waterborne infections. Antimicrobial resistance in Camp. jejuni is increasing, and minor data exist on the effect of antimicrobial resistance on the survival of Camp. jejuni. Water is an important source of campylobacteriosis; thus, we need to have modelling data to predict the survival characteristics of these organisms in water.