**7.1 Central venous catheter biofilms**

Commonly found organisms on catheter biofilm are *S. epidermidis, S. aureus, K. pneumoniae, C. albicans, P. aeruginosa,* and *E. faecalis.* These might get emerged from patient's skin microflora, exogenous microflora from health-care personnel, or infected infusates. It has been reported that inner lumen of long-term catheters (30 days) and an external surface of short-term catheters (<10 days) has more biofilm formation. Microbial growth may depend on the nature of fluid delivered through a central venous catheter, as it has been seen that gram-negative microorganisms grow well in the intravenous fluid than gram-positive organisms [17].

Many studies have been done to control or avoid biofilm formation in these devices. Few remarkable results are:


### **7.2 Mechanical heart valve biofilms**

Microorganisms like *S. epidermidis*, *S. aureus, Streptococcus* species*,* Gram-negative bacilli, diphtheroids*, Enterococci and Candida* species develop biofilm on the components of mechanical heart valves and surrounded heart tissues, which lead to a condition called prosthetic valve endocarditis. Also, it more often develops on the tissue surrounding the prosthesis or on the sewing cuff fabric that attaches a device to the tissue than on the valve itself. The source of the microorganism somehow tells its identity as, if it gets originate from an invasive process like dental work then it possibly belongs to *Streptococcus* species or it also might get originated during surgery (early endocarditis, mainly due to *S. epidermidis*) or from an indwelling medical device.

To prevent initial attachment of the microbes, anti-microbial agents are provided during valve replacement or any invasive process like dental work. It has also been found out that less inflammation was caused when silver coated sewing cuff of St. Jude mechanical heart valve was implanted than an uncoated one [5, 17].

### **7.3 Urinary catheter biofilms**

Organisms which develop biofilm on these devices are *S. epidermidis*, *E. faecalis*, *E. coli*, *Proteus mirabilis*, *P. aeruginosa*, *K. pneumonia* and other Gram-negative organisms [17]. These catheters are tubular latex or silicone devices that are inserted via urethra into the bladder. It may be of an open system in which catheter drains into an open collection center or close system in which it vacates into a securely fastened bag. In open system, catheter gets quickly contaminated and chances of UTI (Urinary Tract Infection) are much more than in closed system. The chances of microbes to develop biofilm and hence causing UTI is more as long as the catheter remains on its place as it has been found out that approximately 10 to 50% of the patients undergoing short-term catheterization (up to 7 days) and around all the patients undergoing long-term catheterization (>30 days) gets infected with UTI [5].

It has been shown in studies that hydrophobicity of both organism and surface is responsible factors for microbial attachment on the catheter as a wide range of microbial colonies are found to be attached on the catheter's surface which displays both hydrophobic and hydrophilic regions [17]. Bacterial attachment is also enhanced by an increase in urinary pH and ionic strength by divalent cations (Mg and Ca). Urease is produced by some of the organisms of this biofilm which is responsible for hydrolyzing the urea to ammonium hydroxide. As a result, pH at the biofilm-urine interface gets higher, which causes precipitation of minerals such as struvite and hydroxyapatite. These biofilms having mineral components form encrustations which can completely block the catheter's inner lumen [5].

Several approaches have been done to control biofilm formation on urinary catheters like the use of antimicrobial ointments and lubricants, bladder instillation,

**157**

*Microbial Biofilms*

tion with lactic acid [17].

**7.5 Intrauterine devices**

**8.1 Dental biofilms**

species of *Corynebacterium*, *Enterococcus* species [5].

**8. Some common biofilm infections**

sucrose and other carbohydrates [11].

**8.2 Native valve endocarditis (NVE)**

**7.4 Contact lenses biofilms**

*DOI: http://dx.doi.org/10.5772/intechopen.90790*

antimicrobial agents in collection bags, impregnation of catheters by silver oxides like antimicrobial agents or systemic antibiotics. Also, biofilm of many Gramnegative microorganisms can be reduced by exposing to mandelic acid in combina-

Microbes get readily attached to the surface of both type of contact lenses i.e. soft contact lenses and hard contact lenses (differentiated according to the material used, design, wear schedule and frequency of disposal). Nature of substrate, water content, polymer composition, electrolyte concentration and type of bacterial strains governs the degree of adherence of microbes to the lenses. The storage case

of a lens has been implicated as the primary source of contamination [5].

*Staphylococcus*, *Serratia* and *Pseudomonas* are some most common bacterial species obtained in contact lenses. *Staphylococci* are found affiliated with contact lens induced peripheral ulcer, blepharitis and conjunctivitis while *Serratia* and *Pseudomonas* species known to contribute in corneal inflammation and infection [18].

The tail part of IUDs which is made up of a plastic microfilament surrounded by nylon sheath is possibly the primary source of infection. Microorganisms that contaminate IUDs are *Lactobacillus plantarum*, *S. epidermidis*, *C. albicans*, *S. aureus*,

Dental biofilms, commonly known as plaque are the most studied biofilm in human. It involves hundreds of species of bacteria. Some significant microbes include *Porphyromonas gingivalis, Bacteroides forsythus*, *Actinobacillus actinomycetemcomitans*, *Treponema denticola*, and a number of *Streptococci* including *Streptococcus mutans* [11]. After a good oral wash or dental cleaning, the tooth enamel acquires a coating called as pellicle which is composed of various proteins and glycoproteins of host origin. Then with the help of adhesion molecules and pilli, first *Streptococci* then *Actinomycetes* colonizes the teeth surface. Bacterial cells start interacting with each other on the pellicle and a number of *Streptococci* and related organisms starts synthesizing insoluble glucan via glucan binding protein. After few successive colonization with few more organisms, demineralization of tooth enamel starts (which leads to caries) by the acids which are produced by fermentation of the dietary

This condition arises due to the interaction between bacteria, vascular endothelium and generally of mitral, aortic, tricuspid and pulmonary valves of the heart. The organisms responsible for these conditions are species of *Streptococcus*, *Staphylococcus*, *Pneumococci*, *Candida*, *Aspergillus,* and some Gram-negative bacteria, which get access to the blood stream via the oropharynx, gastrointestinal, and urinary tract. When the intact endothelium gets damaged, microbes

antimicrobial agents in collection bags, impregnation of catheters by silver oxides like antimicrobial agents or systemic antibiotics. Also, biofilm of many Gramnegative microorganisms can be reduced by exposing to mandelic acid in combination with lactic acid [17].
