a health risk for divers. Anaerobes from these sites included 

 Bacteroides , Clostridium , Butyrivibrio , and Propionibacterium , 

 with the majority of the anaerobic isolates belonging to the 

 genera Bacteroides and Clostridium . 



Total anaerobic counts were made (obligate and facultative) 

 and differentiation was done by replica plating, i.e., incubating 

 one plate in a 10% CO2 atmosphere and the other under total 

 anaerobic conditions. In the Anacostia River, total anaerobic 

 counts ( TAC ) and obligate anaerobic counts ( OAC ) varied from 

 2xl0 2 to 9xl0 3 cells/ml and 10 to 1.8xl0 3 cells/ml, respectively, 

 in the water column. The highest TAC and OAC occurred during the 

 summer, when temperatures were warmer and the dissolved oxygen 

 values were lower, e.g., 1-5 ppm. Sediment TAC and OAC showed 

 similar variation, but were higher than the water column counts. 



Cultures were also analyzed for cytotoxicity, using the Y-l 

 adrenal cell tissue culture assay, and for enterotoxin-like 

 activity in rabbit ligated ileal loops. Several of the isolates 

 were found to be cytotoxic, although weakly so, and several 

 elicited fluid accumulation in ligated loops, indicating 

 potential enterotoxigenicity . Based on these findings, obligate 

 anaerobes should be considered a potential health hazard for 

 divers entering polluted waters. 



Vibrio 



There are many species of the genus Vibrio which can be 

 isolated from aquatic habitats. Vibrios which pose a potential 

 risk to divers include V. cholerae , both 01 and non-01 serotypes, 

 V. vulnificus and group F vibrios. Kaper et al. (1979) 

 recovered 65 isolates of V. cholerae non-01 from Chesapeake Bay 

 water, sediment and shellfish. Salinity appeared to be the 

 primary factor controlling distribution of V. cholerae , with 

 isolates being recovered only in waters ranging from 4-17 ppt . 

 V. cholerae non-01 serotype could be isolated at all times of the 

 year, and thus there was no strong seasonal influence on the 

 distribution of these vibrios. A majority of the isolates were 

 positive in the rabbit ligated ileal loop and mouse lethality 

 tests. Therefore, it is not surprising that non-01 V. cholerae 

 have been implicated in cases of diarrhea (Zafari et al., 1973; 

 Mclntyre et al., 1965), septicemia and encephalitis ( Fearington 

 et al., 1974). In the Kaper et al. study (1979), no correlation 

 was detected between incidence of fecal coliforms and V. cholerae 

 non-01. Thus, coliform counts, which are often used to indicate 

 the level of pollution in a body of water, are not necessarily 

 indicative of the presence of V. cholerae. It should be pointed 

 out that the numbers of V. cholerae non-01 found in the 

 Chesapeake Bay were on the order of 1-10/liter, significantly 

 less than that required for infection if direct ingestion of Bay 

 water were to occur. However, in nutrient enriched waters, such 

 as areas of the Chesapeake Bay exposed to agricultural runoff, 



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