Biomedical subjects

C Kontnick

Publications and source records attributed to C Kontnick.

5 recordsLinked to original sources

PubMed1997

Analysis of cytotoxicity and invasiveness of heterotrophic plate count bacteria (HPC) isolated from drinking water on blood media.

Heterotrophic plate count (HPC) bacteria are naturally present in all aqueous environments. These bacteria undergo multiplication cycles in drinking water, especially in closed containers (bottled water) or in tap water when chlorine levels are dissipated, such as in dead ends in water mains or household plumbing. A study was undertaken to estimate health risk from these naturally occurring bacteria by the determination of cytotoxicity and invasiveness in a human enterocyte cell line. HPC bacteria were isolated from bottled and tap water samples by enumerating them under physical and chemical conditions analogous to human physiology. All HPC bacteria were examined at both log and lag phase of their growth cycles. Bacterial broth supernatant fluids were also tested to serve as critical negative controls. Naturally occurring HPC bacteria demonstrated low invasiveness and cytotoxicity with more than 95% of isolates showing equivalency to broth supernatant fluid. When showing either invasiveness or cytotoxicity, only a small number of cells from the culture were positive. Of those that were positive, log phase HPC bacteria were significantly more cytotoxic and invasive than those from stationary phase. Bacterial broth controls demonstrated varied, but often marked, cytotoxicity.

Bacteria↗

PubMed1994

Rapid detection of vancomycin-resistant enterococci.

Campylobacter blood agar with clindamycin incubated in 6% CO2 served as a medium to both screen for vancomycin resistance and select for presumptive enterococci. Colonies that grew on the medium were specifically identified as enterococci within 30 min by the pyroglutamyl-beta-naphthylamide and rapid bile esculin tests. The combination of a selective medium plus rapid enzyme substrate tests offered an inexpensive means to enumerate vancomycin-resistant enterococci from specimens by using readily available reagents.

Drug Resistance, Microbial↗

PubMed1993

Cryptococcal antigen detection from the urine of AIDS patients.

Cryptococcal disease occurs in < or = 10% of AIDS patients. Detection of the capsular polysaccharide antigen of the yeast in spinal fluid or serum is used to establish the diagnosis. In addition, cryptococcal antigen (CAg) analysis is used to adjust treatment and evaluate recurrence of active disease. A specimen such as urine, obtained noninvasively, would be optimum for this evaluation. Urine, cerebrospinal fluid (CSF), and serum for CAg analysis, and culture of urine and CSF, were obtained for 103 sets of specimens from 92 patients. CSF and urine specimens for CAg were analyzed with and without pronase treatment; serum was analyzed with pronase only. Twenty percent (21 of 103) of specimen sets showed CAg from eight patients. In all cases, patients with positive CSF and/or serum titers also had positive urine titers. Titers were always serum > CSF > urine, with ranges of 1: 64-65000; 1: 64-6250; and 1: 2-512, respectively. Pronase treatment did not affect CSF titers, but 14 of 23 titers from urine treated with pronase were at least one dilution higher than those without treatment. No false-positive reactions were observed during the study. CSF cultures were positive from seven of eight, and urine cultures were positive from five of eight patients with CAg. These results indicate that urine can be used as a specimen for detection of CAg in AIDS patients and that use of pronase may increase its sensitivity.

AIDS-Related Opportunistic Infections↗

PubMed1993

Detection and identification of Mycobacterium directly from BACTEC bottles by using a DNA-rRNA probe.

Detection and identification of mycobacterial species using DNA-rRNA probes from colonies has been used for some time. Guidelines for probe use with a specific minimum growth index (GI) cutoff from BACTEC 12B bottles or its use with 7H9 broth has not been defined. This study defined this minimum GI guideline. Clinical specimens received during the study period were decontaminated and directly inoculated into BACTEC 12B bottles and appropriate solid media. An initial probe test was performed at a GI reading of > or = 100. An additional probe test was made at GI of > or = 300. A total of 1377 specimens were processed with 98 specimens containing 99 isolates of Mycobacterium. Of these, 82 were M. avium complex (MAC), six were M. tuberculosis (Mtb), and 11 were other species. At a GI of > or = 100, 82% of MAC were detected; at a GI of > or = 300, 89% were detected. All Mtb were detected at a GI of > or = 100. The probes correctly identified all isolates from backup 7H9 broths. There were no false-positive probe results for any of the isolates from either BACTEC 12B or 7H9 media. Therefore, the DNA-rRNA probe test at a GI of > or = 300 saves considerable time (on average, 21 days saved) for the detection and identification of Mtb and MAC. This time saving compares with waiting for the production of colonies while retaining acceptable sensitivity and excellent specificity.

Bacterial Typing Techniques↗

PubMedDate not supplied

Differential diagnosis between Streptococcus agalactiae and Listeria Monocytogenes in the clinical laboratory.

Streptococci of the group B (S. agalactiae) and Listeria monocytogenes resemble each other in many morphological and biochemical characteristics. Ten beta-hemolytic strains of each species were subjected to 26 tests commonly and easily performed in the clinical laboratory. Macroscopic and microscopic morphology on solid media showed differences only in the size of the colonies and in the length of the individual organisms. Among many other tests, hippurate hydrolysis and the CAMP reaction were positive in both species. In the presence of these two reaction, a negative catalase test and chaining in broth would make a presumptive diagnosis of S. agalactiae, while motility at 25 C, the presence of the Henry effect, and resistance to furadantin would be indicative of L. monocytogenes.

Bacteriological Techniques↗