Antibiotic resistance has become a major problem in the past few years, as mutated strains of bacteria are passing on useful genes to clones. Bacteria can cause infection in humans as bacteria cells join together to result in colonies and therefore leading to infections which may prove to be fatal. Antibiotics work as they contain Streptomycin sulfate, which is added as a means of removing nucleic acids from the bacteria cells. It works by binding to ribosomes and precipitates out of solution, this then works to remove  rRNA, mRNA, and the DNA of prokaryotic cells such as bacteria.Antibiotic resistance occurs when a mutation causes variation in the genes of a bacteria cell. Naturally, this cell would usually have no advantage over the others, and not cause a problem, however when an antibiotic is introduced, it kills most of the bacteria, however leaves the one which is resistant to form a new colony which is resistant to the certain antibiotic. This is now becoming widespread as making it increasingly more difficult to treat these infections. An example of an epidemic that caused a threat to thousands of lives wasGut bacteria is very useful to us as humans, as it helps build the immune system and help lymphocytes recognise the early signs of pathogens, particularly bacteria. This helps protect the body from disease and infection.This is particularly prominent in newborn babies, as the gut flora colonises the baby’s digestive system immediately after birth.Gut bacteria can additionally be harmful when the body’s environment undergoes abnormal changes such as diet or a drastic change in lifestyle. Imbalance in bacteria in the gut composition is associated with intestinal problems, such as bloating, abdominal pain, and diarrhoea. This can be linked to high medical costs for treatment, furtherly impacting human’s lives.People are more likely to be affected by Inflammatory bowel disease is most common in developed countries such as the USA. Disorders in bacterial recognition by macrophages are heavily related to pathogenesis of inflammatory bowel disease. Furthermore, this could be a result from an abnormal immune response against the microbiota in a susceptible host.A way in which gut bacteria can additionally negatively impact human lives, is through ineffective microbe administration. Microbiota are microorganisms that are in a particular habitat (in the human body in this instance), this plays a vital role in health and disease. For example, the intestinal microbiota (gut flora) can prevent unwanted microbes from colonising the gut, this is known as colonisation resistance. Evidently, this causes the host to be rendered susceptible to colonisation by a particular pathogen, linking back to antibiotic resistance that was mentioned earlier. This is a particularly prominent issue in hospitals throughout history, this is because antibiotics are more readily available/widely used, therefore pathogen exposures are more frequent. Many hospital specific infections evolve from gastrointestinal colonisation. Due to their resistance to antibiotics, treatment is frequently very challenging. Recent studies however, have shown that manipulating the commensal microbiota can prevent and treat various bacterial infections in the intestine. In this review, we discuss the members of the microbiota, as well as the mechanisms, that govern colonisation resistance against specific pathogens. We also review the effects of antibiotics on the microbiota, as well as the unique epidemiology of immunocompromised patients that renders them a particularly high-risk population to intestinal nosocomial infections.