Total aerobic bacteria

Two studies compared the effect of rifaximin to that of neomycin and/or of rifampicin [72, 73] on the fecal flora in rats. In the first study [72] the antibiotic (1, 10, 30 and 100 mg/kg orally for 7 days) did inhibit both aerobic (especially coliforms and cocci) and anaerobic bacterial growth. Its activity was similar to that of neomycin and stronger than that of rifampicin. In the second investigation [73] the antibiotic effect on aerobic microorganisms was specifically investigated. Oral rifaximin treatment (50 mg/kg for 3 days) caused a marked reduction in the number of total aerobic bacteria and salmonellae, while neomycin led only to a decrease in salmonella counts, but did not cause statistically significant changes in the total aerobic bacterial population. 

In addition to the differences in cleaning and disinfection protocols, there are differences in the recommended maximum levels of total aerobic bacteria (TAB) considered acceptable in cooling systems, and to a lesser degree the level of Legionella present, above which a specific response is necessary. 

The most frequently used dip-slide is the total aerobic bacteria/total bacteria count (TAB/TBC). The method employed is to unscrew the cap, remove the dip-slide by the cap, and immerse it into the cooling water sample for 2 to 3 seconds so that both media surfaces are fully covered by liquid. Any excess liquid should be quickly drained and the cap screwed back on the bottle. The bottle should be stored upright for 24 to 36 hours at 25 to 30° C. Then the (usually colored) bacterial colonies should be compared with a chart for conversion to a (reasonably) quantitative interpretation of the results. Typically, the cooling water results will indicate a TAB of between 1 x 103 and 1 x 107 cfu/ml. 

Usually, total aerobic bacteria, molds, and yeasts are counted by using a standard plate count in order to test the microbial limits. The microbial limit test may be customized by performing a screening for the occurrence of Staphylococcus aureus, Pseudomonas aeruginosa, Pseudomonas cepacia, Escherichia coli, and Salmonella sp. [56],... 

FIGURE 5.1 Mean total aerobic bacteria (a, c), yeast and mold (b, d) CFU/mL of high-pressure (600 MPa, Imin), and thermally processed Valencia (65°C, Imin) and navel orange juice (85°C, 25 s). HPP 4 or HPP 10 refers to high-pressure-processed juice stored at 4°C or 10°C Thermal 4 or Thermal 10 refers to thermally processed juice stored at 4°C or 10°C Fresh 4 or Fresh 10 refers to unprocessed juice stored at 4°C or 10°C. ( Initial, week 1, S week 2 week 4, B week 8, S week 12). (From Bull, M.K. et ah, Innovat. Food Sci. Emerg. TechnoL, 5, 135, 2004. With permission.)... 

Table 19.3 Total aerobic bacterial count, coliform bacteria, Enterobacteriaceae and Enterococcus, Salmonella and E. coll, for lettuce growing in late spring and late summer 2004 (Rattler et al., 2005)...

T.A.M.=Total Aerobic Mesophilic bacteria T.A.T.=Total Aerobic Thermophilic bacteria T.An.M.=Total Anaerobic Mesophilic bacteria Coliforms=Total Coliform bacteria... 

Total count for aerobic bacteria averages 150 x 10,000. It is presumed that these units are colony-forming units per milliliter(cfu/ml). 

Aycicek, H., Oguz, U. and Karci, K. (2006) Determination of total aerobic and indicator bacteria on some raw eaten vegetables from wholesalers in Ankara, Turkey. International Journal of Hygiene and Environmental Health 209(2), 197-201. 

The term bioburden is used to describe the concentration of microorganisms in a material this may be either a total number of organisms per millilitre or per gram, regardless of type, or a breakdown into such categories as aerobic bacteria or yeasts and moulds. Bioburden determinations are normally undertaken by the supplier of the raw material, whose responsibility it is to ensure that the material supplied conforms to the agreed specification, but they may also be checked by the recipient. The... 

Microbial limits Total viable count for aerobic bacteria and yeasts/molds. X X... 

---