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Category: Clinical Microbiology
Colonization of Medical Devices by Coagulase-Negative Staphylococci, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818067/9781555811778_Chap04-1.gif /docserver/preview/fulltext/10.1128/9781555818067/9781555811778_Chap04-2.gifAbstract:
In 1981, intravenous catheters infected with staphylococci by perfusion were investigated by scanning electron microscopy (SEM) to demonstrate the mode of adhesion. Bacterial cells, primarily those of staphylococci, followed by Acinetobacter calcoaceticus and Pseudomonas aeruginosa, were shown to be attached to the inner surface of the catheter. The thickest bacterial layers were found in catheters infected by coagulase-negative staphylococci (CoNS). Right heart flow-directed catheters removed from 18 critically ill patients after an average of 2.6 days after insertion were covered by a bacterial biofilm. In a neonatal intensive care unit, CoNS caused the majority of the nosocomial bacteremias. A study of arterial and central venous catheters removed from patients after 1 to 14 days revealed an extensive biofilm on all 42 arterial and 26 central venous catheters. By using special biofilm culture recovery methods, it was shown that 81% of the catheters were colonized by bacteria growing in slime-enclosed biofilms. It was speculated that the colonization represents a nidus for infection and bacteremia in these patients. Staphylococci also produced biofilm on polyvinyl chloride (PVC) endotracheal tubes used in neonates. Adherence of staphylococci to various intravascular catheter materials was investigated; these materials were composed of silicone elastomer, thermoplastic polyurethane, and polyurethane coated with Hydromer, a coating that absorbs water and provides a hydrophilic sheath around the catheter. Production of slime is necessary for Staphylococcus epidermidis colonization and is also observed with many other pathogens, including S. aureus.
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Scanning electron micrograph (magnification, × 5,000) of S. epidermidis KH11. Massive colonization and slime production on cellulose acetate after 24 h of cultivation are shown.
Scanning electron micrograph (magnification, × 5,000) of S. epidermidis KH11. Massive colonization and slime production on cellulose acetate after 24 h of cultivation are shown.
Genetic organization of the S. epidermidis ica operon involved in PIA biosynthesis. The icaABCD genes are cotranscribed. The upstream located icaR gene encodes a regulator protein. M, membrane localized; Sec, secreted; Hairpin, transcription terminator; Pr and Pi, promoters. (Adapted from references 52 and 64.)
Genetic organization of the S. epidermidis ica operon involved in PIA biosynthesis. The icaABCD genes are cotranscribed. The upstream located icaR gene encodes a regulator protein. M, membrane localized; Sec, secreted; Hairpin, transcription terminator; Pr and Pi, promoters. (Adapted from references 52 and 64.)
Two-step model of staphylococcal biofilm formation. The first step in biofilm formation is the adherence of the bacterial cells to a surface. The second step is the imbedding of the cells in a thick slime matrix (biofilm). One type of slime has been identified as PIA. Within this biofilm, cells appear to have reduced physiological activity in an anoxic environment, and exhibit a decreased sensitivity to many antibiotics, compared with their planktonic counterparts.
Two-step model of staphylococcal biofilm formation. The first step in biofilm formation is the adherence of the bacterial cells to a surface. The second step is the imbedding of the cells in a thick slime matrix (biofilm). One type of slime has been identified as PIA. Within this biofilm, cells appear to have reduced physiological activity in an anoxic environment, and exhibit a decreased sensitivity to many antibiotics, compared with their planktonic counterparts.
Biofilm formation by CoNS on catheters and other prosthetic devices
Biofilm formation by CoNS on catheters and other prosthetic devices
CoNS colonize nearly any synthetic polymer
CoNS colonize nearly any synthetic polymer
Adherence of CoNS to polymers precoated with various blood compounds
Adherence of CoNS to polymers precoated with various blood compounds
Antibiotics tested to prevent biofilm formation or to cure staphylococcal foreign-body infection
Antibiotics tested to prevent biofilm formation or to cure staphylococcal foreign-body infection
Synergistic and antagonistic activities of various antibiotic combinations in treatment of staphylococcal biofilm infections
Synergistic and antagonistic activities of various antibiotic combinations in treatment of staphylococcal biofilm infections