Bacteria biochemical tests

Biochemical tests are usually performed after pure cultures have been obtained. The standard indole, methyl red, Voges-Proskauer, citrate, and litmus milk tests may be used to show important physiological characteristics. To study the functional diversity of bacteria, the utilization of carbohydrates, amines, amides, carboxylic acids, amino acids, polymers, and other carbon and nitrogen sources can be tested.28 Dilution-based most-probable number (MPN) techniques with phospholipid fatty acids as biomarkers have been employed for studying different bacterial species in lakes.40 The patterns of antibiotic resistance in bacteria isolated from natural waters have been useful for identifying sources of water pollution.34... 

MacFaddin, J.F. Biochemical Tests for Identification of Medical Bacteria, 3rd Edition, Ljppincott Williams Wilkins, Philadelphia, PA, 2000. 

Several biochemical tests have been developed for screening mine for the presence of bacteria. A common dipstick test detects the presence of nitrite in the urine, which is formed by bacteria that rednce nitrate normally present in the urine. False-positive tests are nncommon. False-negative tests are more common and freqnently are cansed by the presence of gram-positive organisms or P. aeruginosa that do not reduce nitrate. Other causes of false tests include low urinary pEf, frequent voiding, and dilute urine. 

Similar to the trend of biochemical test results the position of AEOO in the Hasse diagram indicates a decline in ecotoxicity. Here, the incomparability of AEOO to the years 1995 and 1994 is due to the bacteria test (eluate) that yields higher values for year 2000 whereas algae (in pore water and eluate) and bacteria in pore water have identical or lower values in 2000 (daphnia tests yield only zero values for all years). 

Bilirubin metabolites are responsible for the brown coloration of faeces. If bilirubin docs not reach the gut. stools become pale in colour. Bilirubin in the gut is metabolized by bacteria to produce stercobilinogen. This is partly reabsorbed and reexcreted in the urine as urobilinogen, and may be detected by simple biochemical tests. W lien high levels of conjugated bilirubin are being excreted, urine may be a deep orange colour, particularly if allow ed to stand. 

Sugar media a standard media used for biochemical tests and contains 1 % sngar in peptone water along with an indicator (Andrade s indicator). A small tube (Durham s fermentation tube) is kept inverted within the large tube containing the sugar media. Upon the production of acid by bacteria... 

To control the microbiological situation, sometimes a full count of microbe species at different locations is required, rather than determination of the presence of certain microbial groups like sHme-forming species, fungi, yeasts, anaerobic bacteria, etc. Conventional methods for identification of microbes include enumeration and screening of individual species isolated from count plates on selective media. Ready-made plates are available for the selection of different types of microbes. Commercial identification systems for industry and medical purposes, based on numerous biochemical tests or other characteristics, are available, including a database that covers practically aU groups of bacteria. 

It is probable that antibiotics will reach the interior of those abscesses which are still relatively small and have only existed for a short period of time. In these cases, too, the spectrum of aerobic and anaerobic bacteria should initially be covered non-specifically by the above-mentioned combination of antibiotics. At the same time, the presence of an amoebic abscess or echinococcosis should be ruled out serologically (as quickly as possible) and aspirated material collected for bacterial and mycotic testing. Depending on the results, the respective antibiotic (and possibly fungistatic) therapy is effected. After 2-3 (-4) days, the efficacy of this targeted treatment is reviewed clinically and biochemically as well as ultrasonographically. If the treatment is considered to have been effective, it is continued until obliteration of the abscess foci is achieved. (12, 29,53, 60, 64, 74, 91, 97, 113)... 

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