E. coli are rod shaped gram negative bacteria
usually found in warm blooded organisms (E.V.Bulychevaa.
Eschericrhia coli may be considered as most prevailing
opportunistic enterobacteria (Lilian
AparecidaSanches, et al. 2017). Along with living organisms e. coli also
lives in water where it hits household and agricultural effluents. They are facultative anaerobes which
form lactate, ethanol, succinate, carbon dioxide and acetate as their metabolic
end products. (E.V.Bulychevaa. et al. 2014).
This bacterium is a main model organism in
microbiology. They are also used in biological engineering. Most of E. coli
strains are harmless, but some serotypes can cause serious food poisoning in
their hosts.. According to the United States Environmental Protection Agency
(USEPA) E. coli is the best indicator of health risk from water contact in
recreational waters (E.V.Bulychevaa. et
al. 2014). E. coli are transmitted by fecal-oral route, food-borne,
environmental or from person to person. They have ability to release
shiga-toxin which destroys host cells in intestine and through bloodstream move
to other body parts such as kidneys and brain and affect them too(EricaKintz,
et al. 2017). E.
coli has been a common
infection pathogen associated with both community acquired and nosocomial
infections. Antibiotic resistance among E coli isolates
continues to increase, limiting the choices of antibiotics available (Hui-HsiuWu, et al. 2016). The Extraintestinal
pathogenic E. coli (ExPEC) is the most common cause of extraintestinal
infections such as urinary tract infections, bloodstream, kidney and other
infections. The prevalence of extraintestinal infections is thought to exceed 7
million medical visits, 1 million emergency visits and 100 000
hospitalizations every year in the USA. (A.R.Manges, 2016).
Pseudomonas aeruginosa is a gram-negative bacillus (Alice
2012) and encompasses
a high colonization and transmission capacity (FatemehNanvazadeh, et al. 2013). The characteristic blue color of
the organism is due to the production of fluorescent siderophores pyoverdin,
pyochelin and pyocyanin which has iron scavenging and oxidant ability
respectively (Alice S. Prince, 2012).
P. aeruginosa is found widely in nature i.e in soil and water. It has
few nutritional requirements and can adapt to intolerable conditions. It
oxidizes glucose and xylose but cannot ferment lactose or other carbohydrates.
If nitrate is available as an inorganic electron acceptot then P. aeruginosa
can grow aerobically or anaerobically as in the lungs of entities with cystic
fibrosis (Alice S. Prince, 2012).
P. aeruginosa is a common multidrug-resistant (MDR) gram-negative
pathogen which may cause pneumonia in hospitalized individuals. P. aeruginosa infections have a high rate of
mortality (ranging from 10% to 70%) particularly in patients given
inappropriate empirical therapy, immunocompromised patients, ICU patients and
drug-resistant P. aeruginosa infections (O.Asuphon, et al. 2016). Pseudomonas aeruginosa is a common lung pathogen and a main
cause of morbidity and mortality in patients with cystic fibrosis (Alaya Mikalauskas, et al.2017). Data from developing countries indicates
that P. aeruginosa is the most
common cause of pneumonia in hospital (29%), and is the third most common cause
of Intensive Care Unit (ICU)-acquired infections (17%). Antimicrobial
susceptibility and pathogenesis mechanisms of P. aeruginosa are
poorly understood (AliBadamchi, et al.
K. 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).
K. pneumonia inhabits a wide variety of hosts ranging from
plants 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 the
skin, mouth and intestine (FahmiYousefKhan,
et al. 2014).
A wide range of hospital acquired infections
are caused by K. pneumoniae which include primary bacteremia, pneumonia,
urinary tract infections, wound infections and intra-abdominal infections(HacerAkturk, et al. 2016) particularly
in susceptible individuals such as newborns, the elderly, or the
chronically ill (Sonal P.Henson, et al.
2017). Recently, in both community and nosocomial settings, it has gained
an increasingly important role in adult meningitis with substantial
geographical diversity in its clinical patterns (FahmiYousefKhan, et al. 2014). In the WHO report of 2014 Klebsiella pneumoniae
is considered as one of the top three
bacteria of international concern on the global status
of antibacterial resistance (Sonal
P.Henson, et al. 2017) causing high numbers of both healthcare- and
et al. 2017). K. pneumoniae have innate
resistance to penicillins such as ampicillin but are prone
to third generation cephalosporins such as ceftriaxone (Sonal P.Henson, et al. 2017). The
limitation in the treatment options for K. pneumoniae infections
is due to the acquisition of antibiotic
resistance genes and intrinsic resistance to several classes of antibiotics
Currently, strains of K. pneumoniae producing
Extended Spectrum Beta-Lactamases (ESBLs) and carbapenemases have spread worldwide
(Dennis J.Doorduijn, et al. 2016).
Proteus mirabilis is a Gram negative motile
bacillus which belongs to Enterobacteriaceae family
(Rakesh D.MistryMD, et al. 2010) (Chi-YuChen , et al. 2012)
Proteus mirabilis inhabits the skin blisters
of the axilla (Rakesh D.MistryMD, et al.
Proteus mirabilis causes urinary
tract infections (AnaUmpiérrez, er al.
2013) and wound infections in humans (Chun-HaoLiu,
et al. 2015). Proteus mirabilis is also a common cause of other types
of hospital-acquired infections, including bacteraemia, meningitis, empyema and
osteomyelitis. Since 1970s along with sporadic infections, sporadic infections
have also been reported (A.Adler, et al.
mirabilis has been model organism
for urease-producing uropathogens (Allison
N. Norsworthy, et al. 2017)
ammonia and elevates the pH of the urine to >7.2(Chi-YuChen , et al. 2012). The
generated ammonia causes severe metabolic disorders and damage of GIT
epithelium by its interaction with the immune system of human (A.Adler, et al. 2013). Infection stones
in 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) frequently
leading to polymicrobial infection(Allison
N. Norsworthy, et al. 2017). Biofilm formation, toxins, adhesins, motility, immunoavoidance
and nutrient gaining are the virulence
factors of Proteus mirabilis for UTIs (Sandra
M. Fox-Moon, et al. 2015).The increased resistance to antimicrobial agents has led not
only to a changes in antimicrobial therapies, but also to poor prognoses and
an increase in the mortality rate of hospitalized patients ( Chi-YuChen , et al. 2012).