title: Analysis of cell wall constituents of biocide-resistant isolates from dental-unit water line biofilms.
abstract: In past years, the significance of microbial resistance to biocides has increased. Twenty biocide-resistant bacterial strains were isolated from dental-unit water line biofilm. All strains resisted high biocide concentrations (up to 100 microg ml(-1)): sodium dodecyl sulphate, hydrogen peroxide, sodium hypochlorite, phenol, Tween 20, ethylenediaminetetraacetic acid, chlorohexidine gluconate, and povidine iodine. Among bacteria, biocide sensitivity is based on permeability of biocides through the cell wall. Gram-positive bacteria are more permeable and susceptible to biocides, whereas gram-negative bacteria have a more complex cell wall and are the least sensitive bacteria. The present study was designed to study the effect of biocides on the cell wall of biocide-resistant bacteria. Peptidoglycan (PG), diaminopimelic acid (DAP), and teichoic acid contents of the cell wall were determined in L-broth and L-broth supplemented with biocides at different temperatures (37 degrees C and 45 degrees C) and pH levels (7 and 9). In general and Gram staining-specific comparison, a significant increase (p < 0.05) in the DAP content of biocide-resistant bacteria was observed at pH 7 and at both temperatures. In tubing-specific comparison, a significant increase in the amount of teichoic acid in air water tubing (37 degrees C at pH 9) and DAP in patient tubing (pH 7 at both temperatures) was observed. In main water pipe, a significant decrease (p > 0.05) in PG content was noticed at 45 degrees C and pH 9. Overall, a significant increase in DAP content may be an important constituent in the manifestation of isolate resistance against various biocides.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus, Lahore, 54590, Pakistan. iramliaq@hotmail.com
authors.forename: Iram
authors.initials: I
authors.lastname: Liaqat
authors.forename: Anjum Nasim
authors.initials: AN
authors.lastname: Sabri
mesh_terms: D018441:Biofilms / Q000187:drug effects*; D002473:Cell Wall / Q000737:chemistry* / Q000187:drug effects; D019551:Dental Disinfectants / Q000494:pharmacology*; D003748:Dental Equipment / Q000382:microbiology*; D003960:Diaminopimelic Acid / Q000032:analysis; D024881:Drug Resistance, Bacterial; D004866:Equipment Contamination; D006090:Gram-Negative Bacteria / Q000737:chemistry* / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000737:chemistry* / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D019552:Infection Control, Dental; D010457:Peptidoglycan / Q000032:analysis; D013682:Teichoic Acids / Q000032:analysis; D014881:Water Supply
chemical_list: D019551:Dental Disinfectants; D010457:Peptidoglycan; D013682:Teichoic Acids; D003960:Diaminopimelic Acid