**5.7. CAUTI with Candida**

## *5.7.1. Introduction*

One of the common causes of catheter associated urinary tract infection is fungal infection. Bacterial infections are accounted for 70.9% of catheter associated urinary infection. *E. coli* is the most commonly isolated organism (41.6%) whereas fungal infections are accounted for 16.6% and mixed fungal and bacterial infections accounted for 12.5% [68]. The National nosocomial infections surveillance (NNIS) data indicated that *C. albicans* caused 21% of catheterassociated urinary tract infections, in contrast to 13% of non-catheter-associated infections [69]. In one study 24% of the cases showing fungal yeast growth. Candida spp. was the commonest. Non-albicans Candida (86%) isolated more commonly than *Candida albicans* (14%) [70]. Candida are commensals, and to be pathogenic, interruption of normal host defenses is crucial which is facilitated in conditions like immunocompromised states as AIDS, diabetes mellitus, prolonged broad spectrum antibiotic use, indwelling devices, intravenous drug use and hyperalimentation fluids [71]. Diabetes mellitus has been reported as the most common risk factor for fungal infection [72, 73]. The duration of catheterization is also an important risk factor as the duration increases the incidence of fungal infection is increased [74].

*5.7.3. Laboratory diagnosis*

**5.8. CAUTI with** *Serratia marcescens*

**5.9. CAUTI with** *Delftia tsuruhatensis*

molecular methods are more reliable [83].

and molecular methods.

mia [85].

**5.11. CAUTI with Staphylococci**

**5.10. CAUTI with** *Achromobacter xylosoxidans*

Urine and materials removed from catheter are needed. Microscopic examinations of gramstained specimen showed pseudohyphae and budding cells. Culture on Sabouraud's agar at room temperature and at 37°C showed typical colonies and budding pseudomycelia [79].

Microbiology of Catheter Associated Urinary Tract Infection

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

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It is facultative anaerobic bacilli gram-negative rod of Enterobacteriaceae family considered opportunistic human pathogen but not a component of human facial flora. It is capable of producing a pigment called prodigiosin, which ranges in color from dark red to pale pink. It is ubiquitously spent in nature and has preference for damp conditions. Though previously known as nonpathogenic, but since 1970s it is associated with multi drug resistant infection due to presence of R factor—a plasmid. A study in Japan showed 6.8% incidence of UTI with this organism [80]. It also causes bacteraemia rarely. Diagnosis is confirmed by culture of the urine specimen or catheter biofilm. Automated bacterial identification systems and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) is

the other modality for diagnosis of serratia as well as other enterobacteriaceae [81].

This non-fermentative gram-negative rod discovered as plant growth-promoting bacterium and potential biocontrol agent against plant pathogens. Infection with this uncommon organism in CAUTI occurs in combination with commonest bacteria *E. coli*, *Klebsiella pneumoniae* and *Pseudomonas aeruginosa*. *D. tsuruhatensis* and *E. coli* coexist and tend to co-aggregate over time and also cooperate synergistically [82]. *D. tsuruhatensis* metabolized citric acid more rapidly leaving more uric acid available in the medium to be used by *E. coli* for dynamic growth of both organisms. Identification of this organism is not confirmatory with culture, so

Achromobacter denitrificans is gram negative bacterium formerly known as *Alcaligenes denitrificans*. Infection with this organism predominantly observed in elderly patients with predisposing factors as urological abnormalities, malignancies and immune-suppression. Rarely it

In polymicrobial biofilm, *Achromobacter xylosoxidans* cohabits with common organisms *E. coli*, *Pseudomonas aeruginosa* and *Klebsiella pneumoniae*. Diagnosis is by bacterial culture

Staphylococci (methicillin-sensitive *Staphylococcus aureus* [MSSA] and methicillin-resistant *S. aureus* [MRSA], *Staphylococcus saprophyticus*. These are the common gram positive bacteria usually responsible for skin and soft tissue infections but rarely cause CAUTI and bacterae-

causes bacteraemia. This bacterium has high level of antibiotic resistance [84].

#### *5.7.2. Structure and pathogenesis*

*Candida albicans* is an oval, budding yeast, which is a member of the normal flora of mucocutaneous membrane. Twenty species of Candida yeasts can cause in human infection but most common is *Candida albicans*. Sometimes it can gain predominance and can produce disease. Other candida species that can cause disease occasionally are *Candida parapsilosis*, *Candida tropicalis* and *Candida krusei* [75]. Although *Candida albicans* are common isolates in CAUTI, *Candida tropicalis* is increasingly reported in CAUTI [76]. The majority of *Candida albicans* infections are associated with biofilm formation on host or abiotic surfaces such as indwelling medical devices, which carry high morbidity and mortality [63, 77]. Several factors and activities contribute to the pathogenesis of this fungus which mediate adhesion to and invasion into host cells, which are in sequences are the secretion of hydrolases, the yeast-to-hypha transition, contact sensing and thigmotropism, biofilm formation, phenotypic switching and a range of fitness attributes [78] (**Figure 7**).

**Figure 7.** Morphology of Candida albicans. Adapted from biomedik8888, Aug 24, 2011. http://www.BioMedik.com.au3.
