The major impetus for bacterial identification came after the advent of solid culture media. Morphological appearance of bacterial colonies was often sufficient for their identification in the laboratory. Even in modern times, preliminary identification of most cultivable bacteria is based on such morphological characters. Advances have been made media for the presumptive identification of common organisms encountered in clinical samples. Phenotypic characterisation of bacteria with, physiological tests with a battery of biochemical tests differentiate related bacterial genera as well as confirm their identity. . Each laboratory can select its own method(s) of identification, provided they are based on scientific / epidemiological evidence; clinical laboratory and standards institute (CLSI) is a widely accepted organization and laboratories in many parts of the world follow its recommendations for bacterial identification. Some of the latest advances in identification include Matrix Assisted Laser Desorption Ionization - Time of Flight Mass Spectroscopy (MALDI-TOF) is a state of art facility used for fast and reliable species-specific identification of bacteria including Mycobacteria and fungi including yeasts. However the single most important factor that decides the method of bacterial identification in any laboratory is the cost involved. In the final analysis, selection of tests for bacterial identification should be based on their standardization with proper scientific basis. Considering the cost and lack of easy availability of commercial kits, we have put forward a simplified and rapid method of identification for most commonly encountered bacterial pathogens causing human infection in India.

A coagglutination procedure for detecting Vibrio cholerae was applied directly to 125 watery fecal samples received in the laboratory for bacteriological culture; many of these were from suspected cases of cholera. Of 47 bacteriologically proved cases of cholera, 44 (93.6%) gave positive results by the coagglutination method. There was a good correlation between the coagglutination method, dark-field microscopy, and culture. Prompt diagnosis of any infectious disease is always advantageous, and this is especially so for a condition like cholera, which has a rapid course of infection. Rapid methods of diagnosis like coagglutination have been found to be useful and successful in diseases like meningitis, streptococcal infections, and salmonella infections (7-9). With this in view, the coagglutination procedure was applied directly to watery fecal samples received in our laboratory. These samples were tested on receipt, or if immediate testing was not possible, they were kept at 2 to 4°C until the time of testing. A 10% suspension of Staphylococcus aureus Cowan I cells was prepared (2). Antisera supplied by the National Institute of Cholera and Enteric Diseases, Calcutta, India, were used for sensitization. For sensitization, 0.1 ml each of the V. cholerae polyvalent and Ogawa serotype (the commonest serotype now encountered in India) antisera was added separately to 1 ml of the 10% staphylococcal suspension. The mixture was left at room temperature for 30 to 45 min and then centrifuged. The sensitized staphylococci in the deposit were resuspended in phosphate-buffered saline containing 0.1% sodium azide to give a final concentration of 2% sensitized cells. This suspension was found to be stable for many months at 4°C. A control to detect nonspecific agglutination was included with each specimen by using unsensitized Cowan I cells. A standard strain of V. cholerae biotype El Tor, serotype Ogawa (AD12-og) obtained from the National Institute of Cholera and Enteric Diseases, Calcutta, India, was tested and found to give clear and strong clumping with Staphylococcus A cells sensitized with V. cholerae polyvalent and Ogawa antisera, but no reaction was seen with unsensitized

A micro-indirect hemagglutination test was developed for detecting antibody against the Ibc protein of group B Streptococcus. Formalin-preserved, tanned sheep erythrocytes were sensitized with a partially purified preparation of Ibc protein from a type Ic strain of group B streptococci. A total of 76% of 103 sera from pregnant and nonpregnant women had demonstrable antibody against this protein, with titers ranging from 10 to 320. Examination of five pairs of mother and cord sera revealed passive transfer of these antibodies from mother to infant. This testing on a limited number of sera also revealed that elevated antibody titers against Ibc protein were more common among carriers of group B streptococci, especially those harboring strains with Ibc protein antigen, than among noncarriers. The technique described was found to be simple, specific, sensitive, and reproducible and may be of value in assessing the immune status of pregnant women as well as for epidemiological purposes.

Summary Samples of amniotic fluid obtained from 48 South Indian women in the third trimester of pregnancy were studied for antimicrobial activity. The growth of Staphylococcus albus, Candida albicans and Clostridium perfringens was inhibited by nearly all samples studied while the growth of Staphylococcus aureus, Escherichia coli and Bacteroides fragilis was inhibited by 50%, 42% and 18% of samples respectively. The growth of Streptococcus faecalis was not inhibited. Using radial immunodiffusion, IgG was measurable in all 10 samples studied (mean 23 mg/dl), whereas IgA was measurable in only three of these samples (mean 1.32 mg/dl). However, while specific IgA against C. albicans was detected by indirect immunofluorescence in 93% of samples, specific IgG against C. albicans was detected in only 26% of samples (P<0.001). Amniotic fluid obtained from parous women had greater inhibitory activity against E. coli (P<0.05) than did the amniotic fluid obtained from nulliparae.

We recently reported a sugar-induced bacterial release of 13-Docosenamide and its ability to quench fluorescein. This simple handle to monitor bacterial growth is readily applicable to develop a quicker antibiotic sensitivity testing method along with a low-cost field-use optical instrumentation. Conditions were standardized to perform this new procedure in the most preferred and CLSI-recommended microdilution format in 12-well strips. A simple and portable optoelectronic prototype was used to capture the image and read the fluorescence signal of the culture medium of the 12-well strips. This new Fluorescence Quenching Method along with the device enabled the choice of the right antibiotic within 8 h of sample collection from the patient. It was compliant to the Clinical Laboratory Standard Institute's quality control guidelines. Clinical assessment of the method using 440 urine samples from Urinary Tract Infection patients against 21 routinely used antibiotics showed a 94.3% match with the results of the Standard Disk Diffusion method. This new method saves the precious time taken for and the cost of antibiotic susceptibility testing for quicker and effective treatment with better compliance.