Klebsiella is a type of bacteria that belongs to a family which commonly thrives in the intestinal tract of human beings, hence the term enterobacteriaceae. The bacteria usually do not move in their habitat. Its other characteristic includes possession of the shape of a rod. This type of bacteria has two kinds of antigens, that is, antigen O and antigen K both of which cause infections. Klebsiella infections commonly occur in the hospital environment especially among the inpatients. The infections have characteristics of being localized and some times very dangerous. Individuals at risk of klebsiella infection include diabetics, alcoholics and those who have undergone surgical operations and organ transplant (Bleich et al, 369). The infection occurs both in human beings and animals. The animals that are infected by klebsiella include rodents, invertebrates, vertebrates and mammals. The disease is infectious and can transmit among human beings, or between animals and humans through direct contact and/ or fecal-oral route.First, klebsiella thrive in a various habitats that consist of various human body parts. The bacteria can manifest in the nose. Here, they may not cause the disease. The bacteria can move along the nasal track, by passing the immune system and they end in the respiratory system; specifically the lungs where it leads to pneumonia infection (Charles River laboratories International, Inc, 3). Klebsiella belongs to a family of enterobacteriaceae meaning that they are normally found to thrive in the intestinal track of humans. They also inhibit the urinary tract. Other places on human body where the bacteria can be found include the gastrointestinal tract, skin surface and pharynx. It is sometimes also found thrive on vegetables grown in areas with dirt or sewage water, soil with fecal contamination and water respectively (Encyclopædia Britannica, 3).Phage Therapy Center (2) states that different types of microorganism among the bacteria, requires special environmental conditions in order to survive, grow and multiply. These special environmental conditions add up to growth requirements. The growth requirement for include for bacteria include nutrients, optimum temperature, optimum PH among others. The PH requirement for klebsiella is about neutral, at around 6.9 to 7. They inhabit the intestinal tract but not the stomach.Bleich et al (371) assert that the stomach is usually acidic due to presence of hydrochloric acid. The intestinal tract is also rich in food nutrients. Human body in good health usually has a temperature of about 37 degree Celsius. This is the optimum temperature for klebsiella. Apart from these special growth require, klebsiella has a special adaptation that enhances its survival in the harsh conditions of its surrounding environment. They forms a membrane around themselves, this membrane is called a biofilm. The biofilm plays in important role as a guard against the cell destructive effects of the sterilizing agents and disinfectants (Cunha, 4). The biofilm must be destroyed before the bacteria cells are destroyed by disinfectants. This feature enhances the survival, growth and multiplication of microbial cells.There are various types of klebsiella species that cause disease in humans. The first species is called klebsiella oxytoca. This is the top four most common pathogens among neonates in hospital facilities. It causes neonatal sepsis. Another infection associated with klebsiella species is that of the kidney that may also cause kidney failure (Brisse and Duijkeren, 3).The second species is klebsiella pneumonia. This is not a very common kind of Klebsiella species. It is a pathogen causing disease infection that is usually life threatening (George, 3). This infection is characterized by sputum with blood, and most common in heavy consumer of alcohol and those suffering from diabetes. There is a strain of the klebsiella species called diazotrophs that do the nitrogen fixation. However it is not a serious pathogen but has a potential to cause infection under special conditions in humans. There are klebsiella species that are also pathogenic in animals. These can still be transmitted from animals to human beings through the earlier mentioned means of direct contact and fecal-oral route. The species include klebsiella pneumonia phylogenetic group (kp1) which is the most common and others like k. variicola, k. planticola, k. oxytoca and finally k. terrigena (Klebsiella, 2).In conclusion, klebsiella is a pathogenic type of bacteria. It belongs to the group of enterobacteriaceae, meaning it is found in the intestinal tract of either human beings or animals of various families. These include the mammals, vertebrates, rodents and also invertebrates. As a pathogen in human beings, it causes a number of infections in human beings. The infections include pneumonia, urinary track infections and neonatal sepsis among others. It is also pathogenic in the above mentioned families of animals that can still transmit the bacteria human beings through direct contact and fecal-oral route as mentioned earlier on. The people at high risk of the infection include those with diabetes mellitus, the heavy consumers of alcohol, the immune compromised, the hospitalized, those that are fed through the catheter and finally premature neonates. The disease is at times severe or rather life threatening. Prevention is the most effective method recommended way of control of klebsiella. This will involve measures that aim at destroying the bacteria before it reaches human beings and cause disease. In cases of infection, the disease can be treated by the use of broad spectrum antibiotics, though at times antibiotics may be ineffective. In such a case, the disease will recur due to the multi-drug resistance of klebsiella species.