Structure E. coli are rod shaped gram negative bacteriausually found in warm blooded organisms (E.
V.Bulychevaa.et al.2014). Habitat Eschericrhia coli may be considered as most prevailingopportunistic enterobacteria (LilianAparecidaSanches, et al. 2017). Along with living organisms e.
coli alsolives in water where it hits household and agricultural effluents. They are facultative anaerobes whichform lactate, ethanol, succinate, carbon dioxide and acetate as their metabolicend products. (E.V.
Bulychevaa. et al. 2014). PathogenecityThis bacterium is a main model organism inmicrobiology. They are also used in biological engineering. Most of E.
colistrains are harmless, but some serotypes can cause serious food poisoning intheir hosts.. According to the United States Environmental Protection Agency(USEPA) E. coli is the best indicator of health risk from water contact inrecreational waters (E.V.Bulychevaa.
etal. 2014). E. coli are transmitted by fecal-oral route, food-borne,environmental or from person to person. They have ability to releaseshiga-toxin which destroys host cells in intestine and through bloodstream moveto other body parts such as kidneys and brain and affect them too(EricaKintz,et al. 2017).
E.coli has been a commoninfection pathogen associated with both community acquired and nosocomialinfections. Antibiotic resistance among E coli isolatescontinues to increase, limiting the choices of antibiotics available (Hui-HsiuWu, et al. 2016).
The Extraintestinalpathogenic E. coli (ExPEC) is the most common cause of extraintestinalinfections such as urinary tract infections, bloodstream, kidney and otherinfections. The prevalence of extraintestinal infections is thought to exceed 7million medical visits, 1 million emergency visits and 100 000hospitalizations every year in the USA. (A.R.Manges, 2016). PSEUDOMONASAERUGINOSAStructurePseudomonas aeruginosa is a gram-negative bacillus (AliceS. Prince,2012) and encompassesa high colonization and transmission capacity (FatemehNanvazadeh, et al.
2013). The characteristic blue color ofthe organism is due to the production of fluorescent siderophores pyoverdin,pyochelin and pyocyanin which has iron scavenging and oxidant abilityrespectively (Alice S. Prince, 2012).HabitatP. aeruginosa is found widely in nature i.e in soil and water. It hasfew nutritional requirements and can adapt to intolerable conditions.
Itoxidizes glucose and xylose but cannot ferment lactose or other carbohydrates.If nitrate is available as an inorganic electron acceptot then P. aeruginosacan grow aerobically or anaerobically as in the lungs of entities with cysticfibrosis (Alice S. Prince, 2012).PathogenecityP. aeruginosa is a common multidrug-resistant (MDR) gram-negativepathogen which may cause pneumonia in hospitalized individuals. P. aeruginosa infections have a high rate ofmortality (ranging from 10% to 70%) particularly in patients giveninappropriate empirical therapy, immunocompromised patients, ICU patients anddrug-resistant P.
aeruginosa infections (O.Asuphon, et al. 2016). Pseudomonas aeruginosa is a common lung pathogen and a maincause of morbidity and mortality in patients with cystic fibrosis (Alaya Mikalauskas, et al.2017).
Data from developing countries indicatesthat P. aeruginosa is the mostcommon cause of pneumonia in hospital (29%), and is the third most common causeof Intensive Care Unit (ICU)-acquired infections (17%). Antimicrobialsusceptibility and pathogenesis mechanisms of P. aeruginosa arepoorly understood (AliBadamchi, et al.2017). K.
PNEUMONIAE StructureK. pneumoniae is a Gram negative, encapsulated, non-motile,lactose-fermenting, facultative anaerobic, bacillus (FahmiYousefKhan, et al. 2014) which belongs to Enterobacteriaceae family (HacerAkturk, et al. 2016).HabitatK. pneumonia inhabits a wide variety of hosts ranging fromplants to mammals, but can also be found in the soil and surface water (Dennis J.Doorduijn, et al.
2016). It is found as the normal flora of theskin, mouth and intestine (FahmiYousefKhan,et al. 2014). PathogenecityA wide range of hospital acquired infectionsare caused by K. pneumoniae which include primary bacteremia, pneumonia,urinary tract infections, wound infections and intra-abdominal infections(HacerAkturk, et al. 2016) particularlyin susceptible individuals such as newborns, the elderly, or thechronically ill (Sonal P.Henson, et al.2017).
Recently, in both community and nosocomial settings, it has gainedan increasingly important role in adult meningitis with substantialgeographical diversity in its clinical patterns (FahmiYousefKhan, et al. 2014). In the WHO report of 2014 Klebsiella pneumoniaeis considered as one of the top threebacteria of international concern on the global statusof antibacterial resistance (SonalP.Henson, et al. 2017) causing high numbers of both healthcare- andcommunity-acquired infections(C.Pichler,et al. 2017).
K. pneumoniae have innateresistance to penicillins such as ampicillin but are proneto third generation cephalosporins such as ceftriaxone (Sonal P.Henson, et al. 2017).
Thelimitation in the treatment options for K. pneumoniae infectionsis due to the acquisition of antibioticresistance genes and intrinsic resistance to several classes of antibioticsCurrently, strains of K. pneumoniae producingExtended Spectrum Beta-Lactamases (ESBLs) and carbapenemases have spread worldwide(Dennis J.Doorduijn, et al. 2016). PROTEUS MIRABILIS Structure Proteus mirabilis is a Gram negative motilebacillus which belongs to Enterobacteriaceae family(Rakesh D.
MistryMD, et al. 2010) (Chi-YuChen , et al. 2012) HabitatProteus mirabilis inhabits the skin blistersof the axilla (Rakesh D.MistryMD, et al.2010).PathogenecityProteus mirabilis causes urinarytract infections (AnaUmpiérrez, er al.
2013) and wound infections in humans (Chun-HaoLiu,et al. 2015). Proteus mirabilis is also a common cause of other typesof hospital-acquired infections, including bacteraemia, meningitis, empyema andosteomyelitis. Since 1970s along with sporadic infections, sporadic infectionshave also been reported (A.Adler, et al.2013).
Proteusmirabilis has been model organismfor urease-producing uropathogens (AllisonN. Norsworthy, et al. 2017)which generatesammonia and elevates the pH of the urine to >7.2(Chi-YuChen , et al. 2012).
Thegenerated ammonia causes severe metabolic disorders and damage of GITepithelium by its interaction with the immune system of human (A.Adler, et al. 2013). Infection stonesin the urinary tract and crystalline biofilms on indwelling urinary catheters,or in patients with urolithiasis are formed by these diverse bacteria (Chi-YuChen , et al.
2012) frequentlyleading to polymicrobial infection(AllisonN. Norsworthy, et al. 2017).
Biofilm formation, toxins, adhesins, motility, immunoavoidanceand nutrient gaining are the virulencefactors of Proteus mirabilis for UTIs (SandraM. Fox-Moon, et al. 2015).The increased resistance to antimicrobial agents has led notonly to a changes in antimicrobial therapies, but also to poor prognoses andan increase in the mortality rate of hospitalized patients ( Chi-YuChen , et al. 2012).