A prospective study was initiated to find out the most suitable method for in vitro antibacterial sensitivity, frequency of organisms causing postoperative infections since 1977, their antimicrobial resistance and whether the drug resistance was plasmid mediated in P. aeruginosa and if it is possible to transfer drug resistance from resistant P. aeruginosa to other species of bacteria. Both Stoke’s and Kirby-Baer methods of in vitro antibacterial sensitivity testing were found to be quite good and gave almost similar results when carried out under standardized conditions, though Stoke’s method gave better agreement with the MIC in most of the cases. The simplicity, accuracy, speed of performance and reproducibility under standardized conditions makes the Stoke’s method ideally suited for a busy diagnostic laboratory to carry out in vitro antimicrobial sensitivity. Staphylococcus aureus was responsible for more than 255 of the postoperative infections in 1977, while in 1985 this reduced to 13%. The reverse was observed with Klebsiella group of organism; about 13% in 1977 and 25% in 1985. Klebsiellae have become more resistant to more drugs. No change was seen in frequent of infections due to P. aeruginosa, E. coli, Proteus species and other gram negative bacilli. It is interesting to note that the resistance to gentamicin has increased for all the organisms during this period. However, inspite of increase in resistance to many other antimicrobial agents, resistance of P. aeruginosa to Poly-myxin B-sulphate has not changed. There has been a major charge for carbenicillin; in 1972 only 14.3% isolates were resistant as against 82.8% in 1977 and 64.9% in 1985. On the basis of different studies carried out to demonstrate presence of R. plasmids in P. aeruginosa, it can be (concluded that multiple drug resistant P. aeruginosa strains of clinical origin carrying transferable drug resistance plasmids are prevalent in a hospital. These strains can transfer resistance to sensitive strains of P. aeruginosa more frequently than to sensitive strains of other related bacteria. They carry both conjugative and nonconjugative drug resistance plasmids. They seem to be an important factor in spread of resistance in a hospital.

The whole cell pertussis vaccine was prepared using glutaraldehyde as an inactivating agent and evaluated with the routinely produced heat inactivated pertussis vaccine (HIPV) for potency, toxicity and stability. Five batches of each of glutaraldehyde inactivated pertussis vaccine (GIPV) and HIPV were prepared for each of B. pertussis strains 134 and 509. The potency of GIPV was very similar to that of HIPV showing no statistically significant differences (p>0.05). The GIPV had about 3 to 8 times less histamine sensitizing activity than HIPV. The mice injected with GIPV showed slightly higher weight gains than those injected with HIPV showing ‘lesser toxicity of GIPV in monse weight gain test. In the innocuity test also, the adsorbed diphtheria-pertussis-tetanus (DPT) vaccine containing GIPV was safer vaccine than the DPT vaccine containing HIPV. The stability of GIPV was similar to that of HIPV. Both the vaccines were stable in potency at 4-8C and 25C for three months while these lost about 60% of their potencies at 37C in 3 months. In this study it has been observed that glutaraldehyde under the prescribed conditions is a better inactivating agent than heat for preparation of a safe, potent and stable pertussis vaccine.

Cerebrospinal fluid (CSF) samples collected from 50 clinically diagnosed cases of meningococcal meningitis and 20 age and sex matched controls were studied for the Immunoglobulins-IgG, IgA and IgM and complement (C3) levels. All the samples showed significant rise of IgG, IgA, and IgM and C3. However the levels were more marked as compared to controls in causes where Neisseria meningitidis could be demonstrated either by smear, Latex agglutination test (LAT) or culture. It was concluded that the high levels of immunoglobulins especially IgM which is normally absent in CSF along with the presence of C3 is diagnostic of pyogenic meningitis but does not indicate the causative organism.

Generation of suppressor cells to Japanese encephalitis virus (JEV) in vitro have been demonstrated. The suppressor cells were effective in mediating the suppression of the CMI and humora) response as assayed by DTH or direct antibody plaque forming cells (IgM PFC). The suppressor cells for IgM PFC were Thyl, 2 and Lyl-2+ and for DTH Thyl. 2 and Lyl+2-. These suppression. The suppressor factors was found to be genetically restricted in its activity and to act at the effector phase of immune response.

Salmonella typhi developed resistance to ampicillin, chloramphenicol, streptomycin and tetracycline after passing through the disinfectants. The variants with altered antibiogram also showed changes in phase lytic patterns. The typables (K1, E1 and O) became nontypable after contact mostly with 4.8% chloroxylenol, and very few by formalin, chlorhexidine + cetrimide, 2% glutaraldehyde and tincture iodine. Some of the variants became susceptible to more number of phages.

The incidence of predominant shigella serogroups and their drug sensitivity was studied in Ludhiana, a thickly populated industrial city of Punjab during 1984-85. Out of 1267 diarrhoeal stool samples examined, Shigella were found in 201 (15.9%) cases, Sh. flexneri was the commonest (51.2%) followed by Sh. dysenteriae (39.3%), Sh. Sonnei (6%) and Sh. boydii (3.5%). Among different serotypes, the more prevalent serotypes were Sh. dysenteriae 1 (36.8%), Sh. flexneri 1b (17.4%), 2a (12.4%) and (10.9%), Sh. sonnei (6%) and Sh. boydii 1 (3.5%). The peak incidence of Sh. dysenteriae was in October and that of Sh. flexneri during October-November, Most Shigella serogroups were highly sensitive to nalidixic acid, gentamicin, gabbromycin, furazolidine, neomycin and cephalothin, while majority of these showed resistance to ampicillin, tetracycline, cotrimoxazole, chloramphenicol and streptomycin.

A total of 200 Klebsiella pneumoniae, isolates of human clinical and environmental sources were tested for Faecal coliform (FC) response, growth at 10C, In dole production and pectin liquefaction as an aid in differenciating environment from non-environmental Klebsiella pneumoniae, on the basis of these tests five main groups were discerned. 75 percent of the clinical isolates and 66 percent of environmental isolates were FC positive and showed no growth at 10C. 26 percent of clinical and 41 percent of the environmental strains produced indole, 5 percent of the clinical and 15 percent of the environmental strains liquefied pectin. An inverse relationship was observed between FC response and growth at 10C in all the strains. The strains of clinical origin and those isolated from hospital environment showed a greater frequency of resistance than the strains from flowers, water and soil.

103 strains of S. havana were received at National Salmonella & Escherichia Centre, Central Research Institute Kasauli (H.P) over a 5 year period (1982-86). Source wise analysis of these showed this serotype to be essentially human pathogen causing mostly systemic infection. The strains produced neither bacteriocines nor haemolysins. All the strains chicken erythrocytes in mannose sensitive fashion.

Neonatal conjunctivitis by Pseudomonas aeruginosa clustered mainly in four outbreaks in the nursery were studied. The probable source-infection relationship was explored according to pigment production (green or poppy red), antimicrobial susceptibilily and aeruginocine typing of P. aeruginosa. Such correlation was fully established in one outbreak and partly in others.

During a period of six months, from April, 1986 to September, 1986, twenty six cases of neonatal meningitis due to Salmonella havana occurred at K.E.M Hospital, Bombay. None of them survived. The organism was multi drug resistant to commonly used antibodies like ampicillin, streptomycin, tetracycline and kanamycin.