Non-agglutinating cholera-like Vibrios in sewage, surface water and sea water

Abstract

Routine bacteriological analysis of sewage work effluents and surface waters has not revealed evidence of Vibrio cholerae or Vibrio El Tor, whereas, non-agglutinating cholera vibrios of Heiberg's groups I and II [so-called non-agglutinating strains (NAG)] have been detected quite frequently. This frequency of NAG presence is approximately equivalent to the presence of Salmonella. Depending on local conditions, quantitative studies of equal amounts of sewage resulted in a ratio of about 1 NAG/10 2 Salmonella/10 7 E. coli. When it became known that NAG vibrios were capable of producing a clinical appearance in man that resembled cholera by its symptoms and severeness, NAG vibrios raised epidemiological interest. Unlike Salmonella, the nutrient requirements of NAG vibrios are moderate. The decisive factors for their persistence in the environmental are attributed to a certain chloride content in the water and an elevated pH value. Both factors are preferably present in sea water. Over a period of 3 yr, samples of water from the Baltic Sea (Lübecker Bucht) were regularly examined for the presence of NAG vibrios. During this period, there have been a number of positive findings in a sample of 100 ml water while identical samples were always Salmonella-negative.