Prevalence of syphilis and biological false positive reactions in VDRL test among injecting drug users: a preliminary study.

The suspensions in normal saline showed almost four log fall in 1 month of storage. However, subsequently there was no marked fall in the viability during an observation period of 12 months. Initial fall in viable count from 109 to 105 CFU/mL at the end of 1 month is possibly due to accumulation of lethal metabolites and/or depletion of nutrients.[4] However, the subsequent loss in viability in normal saline was minimal till 12 months. The survival of vibrios could be due to very low metabolic activity without autolysis in the suspending ß uid. The storage in domestic refrigerator is practical for any average microbiological laboratory in the economically developing countries that do not have freezers or lyophilizing equipment for preservation and the simple method will prove valuable for preservation of V. cholerae.