Growth of Selected Cross-Contaminating Bacterial Pathogens on Beef and Fish at 15 and 35°C. J Food Prot 1994;57:337-340. [PMID: 31113126 DOI: 10.4315/0362-028x-57.4.337]

Behavior of Clostridium perfringens at low temperatures

Refrigerated storage is an important step in the preparation of foods and inadequate storage is one of the main causes of food poisoning outbreaks of Clostridium perfringens. Therefore, growth and germination characteristics of C. perfringens in a temperature range of 3-42 degrees C were determined in fluid thioglycollate broth (FTG) and Dutch pea soup. To study the effect of adaptation, cells were either inoculated from a 37 degrees C pre-culture or from a temperature-adapted pre-culture. Membrane fatty acid patterns were determined at all temperatures to examine the effect of temperature on membrane composition. Spores were either inoculated with and without heat treatment. Adaptation of cells did not influence growth rate nor lag phase. Growth in pea soup, however, was slower and lag phases tended to be more extended compared to FTG. No growth was observed at temperatures < or =10 degrees C and death rates in pea soup were higher than those in FTG at these low temperatures. Cells preserved the membrane fluidity by reducing the arachidic acid content and increasing the lauric acid content when the temperature dropped. This resulted in a net reduction in chain length. Microscopic analysis of cells grown at 15 degrees C revealed a morphological change: cells were elongated compared to those grown at 37 degrees C. These data demonstrate the ability of C. perfringens to adapt to lower temperatures. However, this did not influence growth characteristics compared to non-adapted cells. Spores of C. perfringens did germinate at all temperatures with and without heat-activation. Combining this fact with the extended survival at low temperatures emphasizes the need for adequate heating of refrigerated foods before consumption to eliminate health risks due to C. perfringens.

Infestation of fish-culturing communities with fish-borne bacteria: the Ghanaian case

Twenty different bacterial species were isolated from fishermen and members of communities associated with seven fish ponds with different fertilizer treatments, and an open system. The number and types of the bacterial species were different for the different ponds. Generally, neither the geographical location of the ponds nor the type of fertilizer used could be related to the bacterial flora. Escherichia coli was the predominant species in all the communities, while Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Pseudomonas sp., Shigella sp. or Streptococcus faecalis were common in individuals of communities of sewage-fed pond.