*5.5.1. Introduction*

Enterobacter species, particularly Enterobacter cloacae and *Enterobacter aerogenes*, are important nosocomial pathogens responsible for about 1.9–9% CAUTI, rarely causes bacteremia [57, 58]. *Enterobacter cloacae* exhibited the highest biofilm production (87.5%) among isolated pathogens [53].

#### *5.5.2. Structure and pathogenesis*

Enterobacter bacteria are motile, rod-shaped cells, facultative anaerobic, non-spore-forming, some of which are encapsulated belonging to the family Enterobacteriaceae. They are important opportunistic and multi-resistant bacterial pathogens. As facultative anaerobes, some Enterobacter bacteria ferment both glucose and lactose as a carbon source, presence of ornithine decarboxylase (ODC) activity and the lack of urease activity. In biofilms they secrete various cytotoxins (enterotoxins, hemolysins, pore-forming toxins. Though it is microflora in the intestine of humans, it is pathogens in plants and insects. Amp C β-lactamase production by *E. cloacae* is responsible for cephalosporin resistance. They possess peritrichous, amphitrichous, lophotrichous, polar flagella. *E. aerogenes* flagellar genes and its assembly system have been acquired in bloc from the Serratia genus [59] (**Figure 5**).

bacteremic catheter associated urinary tract infections (CAUTI). However, Enterococcus spp. (28.4%) and Candida spp. (19.7%) were also reported to be most common [62]. In another study, *E. coli* was found the commonest (36%) followed by Enterococcus spp. (25%), Klebsiella

Microbiology of Catheter Associated Urinary Tract Infection

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

33

The most important cause of bacteriuria is the formation of biofilm along the catheter surface [64]. Enterococcus is gram positive bacteria often found in pairs or short chains. Broadly, Enterococcus is in two groups—faecalis and non-faecalis (*E. gallinarum* and *E. casseliflavus*). Enterococcus faecalis formerly classified as part of the group D Streptococcus is a grampositive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals, survive harsh environmental conditions including drying, high temperatures, and exposure to some antiseptics [65]. *E. faecalis* has the important characteristics of complex set of biochemical reactions, including fermentation of carbohydrates, hydrolysis of arginine, tolerance to tellurite, and motility and pigmentation. Presence of the catheter itself is essential for *E. faecalis* persistence in the bladder, *E. faecalis* depends on the catheter implant for persistence via an unknown mechanism that more than likely involves its ability to produce biofilms on

*E. faecalis* produce a heteropolymeric extracellular hair-like fimbrial structure called the endocarditis- and biofilm-associated pilus-Ebp, having three components the organelle (EbpC), a minor subunit that forms the base of the structure (EbpB) and a tip-located adhesin (EbpA) [67]. EbpA is responsible for adhesion in urothelial and catheter surface for biofilm production (**Figure 6**).

Urine sample and biofilm microscopy can identify this gram positive organism. Culture yields the growth of *E. faecalis* in appropriate media. Advanced diagnostic methods like

**Figure 6.** Morphology of Enterococcus. Adapted from Science Photo Library/Alamy Stock Photo Image ID: F6YBC3.

immunological-based detection methods and PCR are rarely needed for diagnosis.

species (20%) and Pseudomonas spp. (5%) [63].

the silicone tubing and immune-suppression [66].

*5.6.2. Structure and pathogenesis*

*5.6.3. Laboratory diagnosis*

#### *5.5.3. Laboratory diagnosis*

The most important test to document Enterobacter infections is culture. Direct gram staining of the specimen is also useful. In the laboratory, growth of Enterobacter isolates is occurs in 24 h or less; Enterobacter species grow rapidly on selective (i.e., MacConkey) and nonselective (i.e., sheep blood) agars.

#### **5.6. CAUTI with Enterococcus**

#### *5.6.1. Introduction*

Enterococci are gram-positive facultative anaerobic cocci, two species are common commensal organisms in the intestines of humans: Enterococcus faecalis (90–95%) and Enterococcus faecium (5–10%) [60]. Though normally a gut commensal, these organisms are commonly responsible for nosocomial infection of urinary tract, biliary tract and blood, particularly in intensive care units (ICU) [61]. *E. coli* is usually the most frequent species isolated from

**Figure 5.** Gram stain picture and morphology of Enterobacter species. Adapted from Gram Stain Kit | Microorganism Stain | abcam.comAdwww.abcam.com/ and Science Prof Online. Gram-negative Bacteria Images: photos of *Escherichia coli*, Salmonella & Enterobacter and Enterobacter aerogenes | Gram-negative microorganism—HPV Decontamination | Hydrogen Peroxide Vapour—Bioquellhealthcare.bioquell.com › microbiology.

bacteremic catheter associated urinary tract infections (CAUTI). However, Enterococcus spp. (28.4%) and Candida spp. (19.7%) were also reported to be most common [62]. In another study, *E. coli* was found the commonest (36%) followed by Enterococcus spp. (25%), Klebsiella species (20%) and Pseudomonas spp. (5%) [63].

#### *5.6.2. Structure and pathogenesis*

*5.5.2. Structure and pathogenesis*

*5.5.3. Laboratory diagnosis*

(i.e., sheep blood) agars.

*5.6.1. Introduction*

**5.6. CAUTI with Enterococcus**

been acquired in bloc from the Serratia genus [59] (**Figure 5**).

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

Enterobacter bacteria are motile, rod-shaped cells, facultative anaerobic, non-spore-forming, some of which are encapsulated belonging to the family Enterobacteriaceae. They are important opportunistic and multi-resistant bacterial pathogens. As facultative anaerobes, some Enterobacter bacteria ferment both glucose and lactose as a carbon source, presence of ornithine decarboxylase (ODC) activity and the lack of urease activity. In biofilms they secrete various cytotoxins (enterotoxins, hemolysins, pore-forming toxins. Though it is microflora in the intestine of humans, it is pathogens in plants and insects. Amp C β-lactamase production by *E. cloacae* is responsible for cephalosporin resistance. They possess peritrichous, amphitrichous, lophotrichous, polar flagella. *E. aerogenes* flagellar genes and its assembly system have

The most important test to document Enterobacter infections is culture. Direct gram staining of the specimen is also useful. In the laboratory, growth of Enterobacter isolates is occurs in 24 h or less; Enterobacter species grow rapidly on selective (i.e., MacConkey) and nonselective

Enterococci are gram-positive facultative anaerobic cocci, two species are common commensal organisms in the intestines of humans: Enterococcus faecalis (90–95%) and Enterococcus faecium (5–10%) [60]. Though normally a gut commensal, these organisms are commonly responsible for nosocomial infection of urinary tract, biliary tract and blood, particularly in intensive care units (ICU) [61]. *E. coli* is usually the most frequent species isolated from

**Figure 5.** Gram stain picture and morphology of Enterobacter species. Adapted from Gram Stain Kit | Microorganism Stain | abcam.comAdwww.abcam.com/ and Science Prof Online. Gram-negative Bacteria Images: photos of *Escherichia coli*, Salmonella & Enterobacter and Enterobacter aerogenes | Gram-negative microorganism—HPV Decontamination |

Hydrogen Peroxide Vapour—Bioquellhealthcare.bioquell.com › microbiology.

The most important cause of bacteriuria is the formation of biofilm along the catheter surface [64]. Enterococcus is gram positive bacteria often found in pairs or short chains. Broadly, Enterococcus is in two groups—faecalis and non-faecalis (*E. gallinarum* and *E. casseliflavus*). Enterococcus faecalis formerly classified as part of the group D Streptococcus is a grampositive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals, survive harsh environmental conditions including drying, high temperatures, and exposure to some antiseptics [65]. *E. faecalis* has the important characteristics of complex set of biochemical reactions, including fermentation of carbohydrates, hydrolysis of arginine, tolerance to tellurite, and motility and pigmentation. Presence of the catheter itself is essential for *E. faecalis* persistence in the bladder, *E. faecalis* depends on the catheter implant for persistence via an unknown mechanism that more than likely involves its ability to produce biofilms on the silicone tubing and immune-suppression [66].

*E. faecalis* produce a heteropolymeric extracellular hair-like fimbrial structure called the endocarditis- and biofilm-associated pilus-Ebp, having three components the organelle (EbpC), a minor subunit that forms the base of the structure (EbpB) and a tip-located adhesin (EbpA) [67]. EbpA is responsible for adhesion in urothelial and catheter surface for biofilm production (**Figure 6**).
