Isolation of Enterobacteriaceae and non-fermenting Gram-negative bacilli (NFGNB) from Dental Unit Water Lines (DUWL) in a tertiary care institutional setup

Background: The quality of dental unit water lines (DUWL) is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from dental units which thereby influence the individual patient outcome and health-care associated morbidity. The aim of the present study was to determine the microbiological quality of water used, presence of biofilms and also the potential of isolated bacterial species in producing biofilms within DUWL. Methods: Thirty DUWL samples were collected from various departments of Manipal College of Dental Sciences, Mangalore. Bacteriological analysis was done for the presence of various bacterial contaminants. Presence of biofilms on DUWLs and potential of bacterial isolates to form biofilm were also determined. Results: Seven of 30 samples (23.3%), were found to be of unsatisfactory quality (coliform count > 200 CFU/ml), most frequently from air/water syringes. A total of 45 strains were isolated from 14 water samples. Genera isolated were Escherichia spp., Enterobacter spp., Klebsiella spp., Pseudomonas spp. and Acinetobacter spp. Four of 10 samples from DUWL tubing showed presence of biofilms (40%), formed mostly by Acinetobacter spp. and Pseudomonas spp. Out of 45 strains that were isolated, 19 strains displayed ability to form biofilms. Maximum number (10) isolates formed biofilms with 48 hours. Conclusion: Exposure to contaminated water from DUWL poses threat to the well-being of the patient and the health care personnel as well. Hence, measures should be initiated to ensure the optimum quality of DUWL water. DOI: http://dx.doi.org/10.5281/zenodo.131977

Characterization of virulence factors and antibiotic resistance pattern of uropathogenic Escherichia coli strains in a tertiary care center [version 2; peer review: 2 approved]

Background: Urinary tract infection(UTI) is one of the commonly prevalent bacterial infection in humans.The uropathogenic E. coli (UPEC) expresses a range of virulence factors that contribute to their pathogenicity. The emergence of multidrug resistance (MDR)-associated UTI is increasing.This study monitors the distribution of virulence factors among UPEC strains to note the antibiogram, outcome and type of associated UTI. Methods:A prospective cross-sectional time-bound study of six months was done on clinically significant urinary isolates of Escherichia coli. Detection of haemolysin production and serum resistance was done by phenotypic methods. Genotypic characterization of the virulence genes (papC, iutA, hlyA, cnf1) was done by multiplex PCR. Demographic data, clinical history, antibiogram and type of UTI was collected from clinical case records. Results:75 E.coli isolates from patients with suspected UTIs were included. Females had a higher preponderance of UTI (66.7%). 93% of patients were adults and the remaining 7% were from paediatrics.  24 (32%) isolates showed haemolysis by plate haemolysis and all isolates were serum-resistant. Out of 75 isolates, 65 were positive for at least one of four targeted genes, while remaining ten isolates were negative for all four genes.Multidrug resistance was found in 40 (53.3%) isolates. 97.4% of the UTI cases had a favourable clinical outcome at discharge. Mortality due to urosepsis was 2.6%. Conclusion:Association of hemolysin production with resistance to imipenem and norfloxacin in UPEC strains was significant.Presence of hlyA gene is positively associated with ceftazidime resistance. Nitrofurantoin, piperacillin, tazobactam, and cefaperazone sulbactam are possible candidates for empirical therapy of UTIs. Drugs like aminoglycosides, carbapenems and fosfomycin may be used as reserve drugs in the treatment of MDR-UTI.However, inappropriate usage can increase antibiotic resistance. Hence proper selection of antibiotics in hospitals taking into account the local antibiogram is needed to reduce the emergence of antibiotic resistance

Effect of trace elements on surface hydrophobicity and adherence of <i>Escherichia coli </i>to uroepithelial cells

681-685Trace elements have significant effect on the physiology of bacteria. Variation in the concentration of trace elements may affect the expression of virulence by microorganisms. The effect of trace elements on hydrophobicity and adherence of E.coli to uroepithelial cells was studied. Increasing concentrations of Ca2+, Mg2+, Fe3+ and Zn2+ significantly decreased the surface hydrophobicity. Toxic trace elements like Co2+, Cu2+, Mn2+, and Ni2+ did not alter surface hydrophobicity. With regards to adherence of E.coli to uroepithelial cells, only Mg2+ had significant effect. Toxic trace elements decreased the rate of cell adherence. The pathogenic strains of E. coli showed higher surface hydrophobicity and better cell adherence compared to the nonpathogenic strains. There was good correlation between surface hydrophobicity and cell adherence at higher concentrations (0.1 to 0.2mM) of Fe2+ and Zn2+. The results indicated that trace elements can significantly affect surface hydrophobicity and adherence of E.coli to uroepithelial cells. Such effect may have a significant impact on the initial stages of bacterial infection

Microbial assessment of dental unit waterlines in an institutional setup in Karnataka, South India

Background and Aim: Biofilms in dental unit waterlines (DUWLs), suction hoses, and fittings are a potentially significant source of cross-contamination posing significant health risk as these may come into contact with patients during treatment. The purpose of this in vitro study was to identify the spectrum of bacterial flora colonizing the DUWLs and to detect pathogenic microorganisms present in such an environmental niche. Materials and Methods: Thirty DUWL samples were collected from in use dental units selected randomly from various clinical departments. Samples were collected from the following devices; 3-in-1 syringe waterline, section of waterline tubing supplying the 3-in-1 syringe, and the air rotor water. The samples were subjected to bacteriological analysis, and all bacterial isolates were tested for their ability to form biofilms. Results: A descriptive analysis of the results obtained was carried out, and it was observed that 7 out of 30 (23.3%) samples collected from DUWL were supplying water of unsatisfactory quality with species of low-pathogenicity bacteria isolated present in significant numbers; four of ten (40%) water supply lines contained bacterial biofilms; and the species with greatest capability to form biofilms were Enterobacter species (spp.). In addition, the results were also subjected to Chi-square test which revealed no statistical difference between the species and the location of collection of samples. Conclusion: Within the limitations of this study, it is concluded that DUWLs are not totally free of contamination. Microbial biofilms are a significant source of cross-contamination and cross-infection in the dental clinic environment