*5.2.1. Introduction*

growth and proliferation of other harmful species of bacteria. Even it plays an important

*E. coli* was discovered in 1885 by Theodor Escherich, German bacteriologist, is gram negative rod, lactose fermenter, composed of one circular chromosome which is common facultative anaerobes in colon and farces of human. Distribution is diverse and most of them are harmless belonging to genus Escherichia. Harmful species causes infection of urinary tract, gastrointestinal tract, respiratory system and rarely bacteraemia and septicemia. Phylogenetic analysis of *E. coli* showed majority of the strains responsible for UTI belongs to the phylogenetic group

It has three antigens O-cell was antigen, H- flagella antigen and k- Capsular antigen. It has pili—a capsule, fimbriae, endotoxins and exotoxins also. Uropathogenic *E. coli* use P fimbriae (pyelonephritis-associated pili) to bind urinary tract endothelial cells. Vast majority of catheter-colonizing cells (up to 88%) express type 1 fimbriae and around 73% in *E. coli* causing CAUTI [20]. In UPEC fimbrial genes are ygiL, yadN, yfcV, and c2395 [21]. Pathogenesis of CAUTI initiated with UPEC colonization in periurethral and vaginal areas. Then it ascends to bladder lumen and grows as planktonic cells in urine. Sequentially adherence to bladder epithelium, then biofilm formation and invasion with replication and kidney colonization and finally bacteremia [22] (**Figure 1**).

Diagnosis of *E. coli* infection is simple, by isolation and laboratory identification of bacterium from urine or biofilm. Laboratory diagnosis by culture of specimen—urine or catheter biofilm in blood agar, MacConkey's agar or eosin-methylene blue agar (which reveal lactose fermentation). Immunomagnetic separation and specific ELISA, latex agglutination tests, colony immunoblot assays, and other immunological-based detection methods are other ways for

**Figure 1.** Gram stain picture and morphology of *E. coli*. Adapted from CCBC faculty web. BIOL 230 Lab Manual: gram stain of *E. coli* and infection landscapes: *Escherichia coli*. http://faculty.ccbcmd.edu/courses/bio141/labmanua/lab16/

role in current biological engineering.

B2 and D, while in smaller percentage belong to A and B1 [19].

26 Microbiology of Urinary Tract Infections - Microbial Agents and Predisposing Factors

*5.1.2. Structure and pathogenesis*

*5.1.3. Laboratory diagnosis*

diagnosis of *E. coli*.

gramstain/gnrod.html.

Proteus species, member of the Enterobacteriaceae family of gram-negative bacilli are distinguishable from most other genera by their ability to swarm across an agar surface [23, 24]. Proteus species are most widely distributed in environment and as other enterobacteriaceae, this bacteria is part of intestinal flora of human being [25, 26]. Proteus also found in multiple environmental habitats, including long-term care facilities and hospitals. In hospital setting, it is not unusual for proteus species to colonize both the skin and mucosa of hospitalized patient and causing opportunistic nosocomial infections. It is one of the common causes of UTI in hospitalized patients undergoing urinary catheterization [26, 27].

UTIs are the most common manifestation of Proteus infection. Proteus infection accounts for 1–2% of UTIs in healthy women and 5% of hospital acquired UTIs. Catheters associated UTI have a prevalence of 20–45%. Proteus mirabilis causes 90% of proteus infection and proteus vulgaris and proteus penneri also isolated from long-term care facilities and hospital and from patients with underlying disease or specialized care. Most common age group is 20–50 years. More common in female group and the ratio between male female begins to decline after 50 years. UTI in men younger than 50 are usually caused by urologic abnormalities. Patients with recurrent infections, those with structural abnormalities of the urinary tract, those who have had urethral instrumentation or catheterization have an increase frequency of infection caused by proteus species [28].

#### *5.2.2. Structure and pathogenesis*

Proteus mirabilis produces an acidic capsular polysaccharide which was shown from glycose analysis, carboxyl reduction, methylation, periodate oxidation and the application high resolution nuclear magnetic resonance techniques. Proteus species possess an extracytoplasmic outer membrane, a common feature shared with other gram-negative bacteria. Infection depends upon the interacting organism and the host defense mechanism. Various component of the membrane interplay with the host to determine virulence. Virulence factors associated with adhesion, motility, biofilm formation, immunoavoidance, nutrient acquisition and as well as factors that cause damage to the host [29, 30] (**Figure 2**).

Certain virulence factors such as adhesin, motility and biofilm formation have been identified in Proteus species that has a positive correlation with risk of infection. After attachment of Proteus with urothelial cells, interleukin 6 and interleukin 8 secreted from the urothelial cells causes apoptosis and mucosal endothelial cell desquamation. Urease production of proteus also augments the risk of UTI. Urease production, together with the presence of bacterial motility and fimbriae or pili, as well as adhesins anchored directly within bacterial cell membrane may favor the upper urinary tract infection. Once firmly attached on the uroepithelium or catheter surface, bacteria begin to phenotypically change, producing exopolysaccharides that entrap and protect bacteria. These attached bacteria replicate and form microcolonies that eventually mature into biofilms [31, 32]. Once established, biofilms inherently protect uropathogens from antibiotic and the host immune response [33, 34]. Proteus mirabilis as with other uropathogens is capable of adapting to the urinary tract environment and acquiring nutrients. And this is accomplished by the production of degradative

Pseudomonas is third ranking causes nosocomial UTI about 12%, where *E. coli* remain on the top [41]. CAUTI is directly associated with duration of catheterization. Within 2–4 days of

Microbiology of Catheter Associated Urinary Tract Infection

http://dx.doi.org/10.5772/intechopen.80080

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Pseudomonas aeruginosa is a gram-negative, rod shaped, asporogenous and monoflagellated, noncapsular bacterium but many strains have a mucoid slime layer. Pseudomonas has an incredible nutritional versatility. Pseudomonas can catabolize a wide range of organic molecule including organic compounds such as benzoate. This, then make Pseudomonas a very ubiquitous microorganism and Pseudomonas is the most abundant organism on earth [43] (**Figure 3**).

Pseudomonas is widely distributed in nature and is commonly present in moist environment of hospitals. It is pathogenic only when introduce into areas devoid of normal defense such as disruption of mucous membrane and skin, usage of intravenous or urinary catheters and neutropenia due to cancer or in cancer therapy. Its pathogenic activity depends on its antigenic structure, enzymes and toxins [44]. Among the enzymes Catalase, Pyocyanin, Proteases, elastase, haemolysin, Phospholipase C, exoenzyme S and T and endotoxin and endotoxin A play role in disease process and as well as immunosuppression. Pseudomonas can infect almost any organ or external site. Pseudomonas in invasive and toxigenic. It attached to and colonized the mucous membrane of skin. Pseudomonas can invade locally to produce systemic disease and septicemia. Pseudomonal UTs are usually hospital acquired and are associated with catheterization, instrumentation and surgery. These infections can involve the urinary tract through an ascending infection or through bacteriuria spread. These UTIs may be a source of bacteraemia or septicemia [45].

Identification of bacterium with microscopy is simple method of identification of pseudomonas. Culture and antibiotic sensitivity pattern can be done in most laboratory media commonly on blood agar or eosin-methylthionine blue agar. Pseudomonas has inability to ferment lactose and has a positive oxidase reaction. Fluorescence under UV light is helpful in

**Figure 3.** Gram stain picture and morphology of Pseudomonas aeroginosa. Adapted from Science News. A new antibiotic uses sneaky tactics to kill drug-resistant Pseudomonas aeruginosa illustration and Pseudomonas Aeruginosa

Stock Photos & Pseudomonas Aeruginosa Stock Images—Alams. https://www.alamy.com › stock-photo.

catheterization 15–25% patients develop bacteriuria [42].

*5.3.2. Structure and pathogenesis*

*5.3.3. Laboratory diagnosis*

**Figure 2.** Gram stain picture and morphology of Proteus. Adapted from CCBC faculty web. BIOL 230 Lab Manual: gram stain of Proteus mirabilis and Proteus vulgaris bacteria (SEM) | Macro & Micro: Up Close and Personal | Pinterest | Microbiology, Bacteria shapes and Fungi. https://www.pinterest.com › pin.

enzymes such urease and proteases, toxins such as Haemolysin Hpm A and iron nutrient acquisition proteins.

#### *5.2.3. Laboratory diagnosis*

The infection with Proteus can be diagnosed by taking a urine sample for microscopy and culture which is sufficient in most of the cases except in few cases where advanced diagnostic tools are used. If the urine is alkaline, it is suggestive of infection with Proteus sp. The diagnosis of Proteus is made on swarming motility on media, unable to metabolized lactose and has a distinct fishy door. Ultrasound or CT scan to identify renal stone (Struvite stone) or to visualized kidneys or surrounding structures. It will allow to exclude other possible problems, mimicking symptoms of urinary tract infection [35, 36].

#### **5.3. Pseudomonas in CAUTI**

#### *5.3.1. Introduction*

Pseudomonas is a gram-negative bacteria belonging to the family Pseudomonadaceae and containing 191 validly described species [37]. Because of their widespread occurrence in water and plant seeds, the pseudomonas was observed in early history of microbiology. Pseudomonas is flagellated, motile, aerobic organism with Catalase and oxidase-positive. Pseudomonas may be the most common nuclear or of ice crystals in clouds, thereby being of utmost importance to the formation of snow and rain around the world [38]. All species of Pseudomonas are strict aerobes, and a significant number of organisms can produce exopolysaccharides associated with biofilm formation [39]. Pseudomonas is an opportunistic human pathogen that is especially adept at forming surface associated biofilms. Pseudomonas causes catheter associated urinary tract infection(CAUTIs) through biofilm formation on the surface of indwelling catheters, and biofilm mediated infection including ventilator associated pneumonia, infections related to mechanical heart valves, stents, grafts, sutures, and contract lens associated corneal infection [40].

Pseudomonas is third ranking causes nosocomial UTI about 12%, where *E. coli* remain on the top [41]. CAUTI is directly associated with duration of catheterization. Within 2–4 days of catheterization 15–25% patients develop bacteriuria [42].
