Incidence ofSalmonellaon Fresh Fruits and Vegetables Affected by Fungal Rots or Physical Injury

Abstract

Enriched wash from healthy and decayed portions of 341 fruits and vegetables collected in the marketplace and affected by fungal rots were tested for suspected Salmonella appearing as black, hydrogen sulfide-positive colonies on Salmonella-Shigella agar incubated at 37°C. Suspected Salmonella occurred in 20.2% of healthy and in 26.4% of decayed portions, two-thirds of which were caused by Alternaria and Botrytis. In a similar analysis of 121 samples with mechanical injuries, in which two-thirds were gouges, cuts, and bruises, there were no significant differences in Salmonella incidence between injured and uninjured portions. Of 332 suspected Salmonella randomly isolated from healthy and decayed or injured portions, 17 (5.1%) were confirmed as Salmonella by physiological and serological testing. When tomato, potato, and onion tissues were inoculated with Salmonella typhimurium, populations of that bacterium increased by one to two logs over a 48-h incubation at room temperature. Coinoculation of tissues with S. typhimurium and Botrytis or Rhizopus, but not Alternaria or Geotrichum, caused a statistically significant increase in populations of Salmonella compared with the controls.