The term "probiotic" was first used in 1965, by Lilly and Stillwell, to describe substances secreted by one organism which stimulate the growth of another. The use of antibiotics, immunosuppressive therapy and irradiation, amongst other means of treatment, may cause alterations in the composition and have an effect on the GIT flora. Therefore, the introduction of beneficial bacterial species to GI tract may be a very attractive option to re-establish the microbial equilibrium and prevent disease. Prebiotic is a non-digestible food ingredient that confers benefits on the host by selectively stimulating one bacterium or a group of bacteria in the colon with probiotic properties. Both probiotics and prebiotics are together called as Synbiotics. Various bacterial genera most commonly used in probiotic preparations are Lactobacillus, Bifidobacterium, Escherichia, Enterococcus, Bacillus and Streptococcus . Some fungal strains belonging to Saccharomyces have also been used. Probiotics have been shown to be effective in varied clinical conditions- ranging from infantile diarrhoea, necrotizing enterocolitis, antibiotic-associated diarrhoea, relapsing Clostridium difficle colitis, Helicobacter pylori infections, inflammatory bowel disease to cancer, female uro-genital infection and surgical infections. Lactobacillus rhamnosus strain GG has proven beneficial affects on intestinal immunity. It increases the number of IgA and other immunoglobulins secreting cells in the intestinal mucosa. It also stimulates local release of interferons. It facilitates antigen transport to underlying lymphoid cells, which serves to increase antigen uptake in Peyer's patches. Probiotics are live microorganisms, so it is possible that they may result in infection in the host. The risk and morbidity of sepsis due to probiotic bacteria should be weighed against the potential for sepsis due to more pathological bacteria and the morbidity of diseases for which probiotic bacteria are being used as therapeutic agents. Also, future, well-designed placebo controlled studies with validated results are required for ascertaining the true health benefits of probiotics The important point in this regard is careful selection of the probiotic agent, its dose standardization and a thorough knowledge of its beneficial effects.

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Quorum sensing in prokaryotic biology refers to the ability of a bacterium to sense information from other cells in the population when they reach a critical concentration (i.e. a Quorum) and communicate with them. The “language” used for this intercellular communication is based on small, self-generated signal molecules called as autoinducers. Quorum sensing is thought to afford pathogenic bacteriaa mechanism to minimize host immune responses by delaying theproduction of tissue-damaging virulence factors until sufficientbacteria have amassed and are prepared to overwhelm host defensemechanisms and establish infection. Quorum sensing systems are studied in a large number of gram-negative bacterial species belonging to α, β, and γ subclasses of proteobacteria. Among the pathogenic bacteria, Pseudomonas aeruginosa is perhaps the best understood in terms of the virulence factors regulated and the role the Quorum sensing plays in pathogenicity. Presently, Quorum sensing is considered as a potential novel target for antimicrobial therapy to control multi/all drug-resistant infections. This paper reviews Quorum sensing in gram positive and gram negative bacteria and its role in biofilm formation.

In recent years the use of immunomodulating therapy to treat various cancers has been on the rise. Three checkpoint inhibitors have been approved by the Food and Drug Administration (ipilimumab, pembrolizumab and nivolumab). The use of these drugs comes with serious adverse events related to excessive immune activation, collectively known as immune-related adverse events (irAEs). We conducted a system-based review of 139 case reports/case series that have described these adverse events between January 2016 and April 2018, found in the PubMed database. There was a broad spectrum of presentations, doses and checkpoint inhibitors used. The most common check point inhibitor observed in our literature review was nivolumab. The most common adverse effects encountered were colitis (14/139), hepatitis (11/139), adrenocorticotropic hormone insufficiency (12/139), hypothyroidism (7/139), type 1 diabetes (22/139), acute kidney injury (16/139) and myocarditis (10/139). The treatment most commonly consisted of cessation of the immune checkpoint inhibitor, initiation of steroids and supportive therapy. This approach provided a complete resolution in a majority of cases; however, there were many that developed long-term adverse events with deaths reported in a few cases. The endocrine system was the mostly commonly affected with the development of type 1 diabetes mellitus or diabetic ketoacidosis being the most frequently reported adverse events. While immunomodulating therapy is a significant advance in the management of various malignancies, it is capable of serious adverse effects. Because the majority of the cases developed pancreatic dysfunction within five cycles of therapy, in addition to the evaluation of other systems, pancreatic function should be closely monitored to minimize adverse impact on patients.

The multi drug resistant gram negative bacteria especially Pseudomonas aeruginosa and Acinetobacter species are on the rise. The major defense in these bacteria against beta-lactam antibiotics is production of metallo beta lactamases (MBLs) which degrade this group of antibiotics including carbapenems. Till now five main types of MBLs have been described throughout the World--IMP, VIM, SPM, GIM and SIM. A new MBL has been recently reported in P. aeruginosa from Australia--bla AIM-1. There are no standard guidelines by CLSI for detection of these enzymes in various bacteria. A number of phenotypic tests based on different beta lactam-inhibitor combinations are being evaluated and used for routine testing. Regarding the treatment options--colistin, various antibiotic combinations and a few novel antibiotics are being tried and evaluated. Prevention is based on age old practices of strict infection control and judicious use of antibiotics.