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Biomedical subjects

T R Franson

Publications and source records attributed to T R Franson.

At least 37 records · Page 2Linked to original sources
PubMed1986

Persistent in vitro survival of coagulase-negative staphylococci adherent to intravascular catheters in the absence of conventional nutrients.

The in vitro survival of coagulase-negative staphylococci in media devoid of routine nutritional supplementation was assessed in the presence and absence of catheter materials to evaluate bacterium-device interactions. Strains of slime- and non-slime-producing coagulase-negative staphylococci were suspended in phosphate-buffered saline together with multiple segments of polyvinyl chloride (PVC), Teflon, Silastic, and polyurethane catheters and in control suspensions without catheters. Catheters were removed at 2 min and 24, 48, 72, and 96 h of incubation and washed thoroughly, and semiquantitative roll cultures were performed on blood agar. In addition, after 96 h catheters were introduced into tryptic soy broth (TSB), and roll cultures were performed after 18 h of incubation. Results demonstrated that after 96 h, 6 of 32 catheter specimens (4 PVC) had greater than 10 CFU of coagulase-negative staphylococci per catheter; after TSB addition, 18 of 32 catheter specimens had greater than or equal to 100 CFU per catheter (8 of 8 PVC catheters had greater than 1,000 CFU per catheter). In control suspensions, no growth was seen at 96 h or after TSB addition. No differences in the survival of slime- versus non-slime-producing strains were observed in control or catheter studies. These findings suggest that both slime- and non-slime-producing coagulase-negative staphylococci survive in vitro on catheters (especially PVC) in the absence of conventional nutrients and can proliferate on catheters when nutrients are added. Catheter-adherent coagulase-negative staphylococci appear to possess survival mechanisms under adverse conditions which may relate to the genesis of occult foreign-body-associated infections.

Bacterial Adhesion↗
PubMed1986

Prevalence of hepatitis B carriers in a mental health in-patient facility: implications for employee screening and vaccination.

Health care employees in a variety of institutional settings may be exposed to Hepatitis B virus through blood contact with patients carrying this infectious agent. Employees may be protected from such risk by administration of pre-exposure Hepatitis B vaccine or post-exposure immunoglobulin prophylaxis. Prior to establishing a Hepatitis B vaccination program for employees, a prevalence survey of hepatitis B surface antigen (HBsAg) positivity in mental health care facility inpatients was conducted to assess employee exposure risk. Survey results demonstrated that 15/270 inpatients (5.5 percent) had positive HBsAg serologies. These results suggest that positivity may be much higher in mental health care facilities than in acute care hospitals. Mental health care facilities should routinely survey inpatient populations for the presence of HBsAg positivity and consider establishing Hepatitis B serologic screening and vaccination programs for personnel involved in delivering care.

Epidemiologic Methods↗
PubMed1985

Influence of bacterial adherence to intravascular catheters on in-vitro antibiotic susceptibility.

Slime-producing and non-slime-producing strains of coagulase-negative staphylococci (CNS) were evaluated for nafcillin susceptibility in the presence and absence of polyvinylchloride (PVC) catheters. Semiquantitative roll cultures of catheters with adherent organisms after exposure to predicted bactericidal concentrations of nafcillin were carried out to assess survival of these organisms. Slime-producing and non-slime-producing CNS had similar minimum inhibitory (MIC) and bactericidal (MBC) concentrations in the absence of catheters and similar MIC in the presence of catheters. However, the mean MBC of slime-producing CNS, and to a lesser extent of non-slime-producing strains was higher in the presence than in the absence of catheters. Slime-producing CNS were recovered from PVC catheters after overnight incubation in cidal concentrations (greater than 4.0 micrograms/ml) of nafcillin (average 350 colony-forming units per 1 cm). Thus nafcillin-sensitive CNS strains, particularly those producing slime, are able to survive exposure to cidal concentrations of the drug when adherent to PVC catheters.

Adhesiveness↗
PubMed1985

A quality control analysis of aminoglycoside management.

Aminoglycoside administration practices were evaluated in a teaching hospital using three study methods: a chart review of 40 randomly selected patients receiving aminoglycosides was conducted retrospectively; 93 health care personnel involved in ordering and administering aminoglycosides to patients were interviewed regarding their understanding of aminoglycoside utilization practices; and ten patients having serum peak and trough aminoglycoside determinations were closely monitored for accuracy of dose administration and obtaining blood specimens at appropriate times. The chart review showed that during 15 of 32 evaluable therapy courses no determinations of serum aminoglycoside concentration were obtained. The survey demonstrated that only 24% of the residents actually used the results of peak and trough determinations to adjust dosage regimens. Direct observation of health care personnel disclosed only two of ten instances in which doses were administered and serum concentration specimens obtained with no apparent problems. Most personnel in our hospital were unaware of these pervasive suboptimal or inconsistent practices associated with aminoglycoside administration and interpretation of laboratory results.

Aminoglycosides↗
PubMed1985

Implementing a successful hepatitis B vaccination program.

Health care personnel with frequent blood contact are at high risk for being exposed to and developing hepatitis B infection. Exposure to unidentified infectious patients may lead to personnel inadvertently foregoing appropriate, passive immunoprophylaxis. For these reasons, our hospital elected to conduct an aggressive program to administer hepatitis B vaccine to all employees at high risk for exposure to hepatitis B virus, thus protecting such employees from inadvertent occupational exposure. Administrators agreed to offer the vaccine as a free employee health benefit. "High-risk" employees attended mandatory inservice presentations covering hepatitis B disease, vaccine safety and efficacy, and related concerns. High-risk individuals were required to either receive vaccine or sign "informed refusal" forms. The vaccine clinic was organized to accommodate employee work schedules. Of high-risk employees eligible for vaccination, 90% completed a three-dose vaccine course. Extensive inservice education, financial and administrative support, and careful advance planning are all crucial in achieving high compliance with vaccination programs. A description of key steps in designing a successful vaccination program is outlined.

Hepatitis B↗
PubMed1984

Inhibition by sugars of Candida albicans adherence to human buccal mucosal cells and corneocytes in vitro.

The adherence and inhibition of adherence of Candida albicans to epithelial cells was studied for human cells obtained from skin (corneocytes) and buccal mucosa. The yeast adhered to both kinds of cells, although in somewhat greater numbers to buccal mucosal cells. Adherence to the cells of different individuals was variable, but the ratios of values for the two kinds of cells from a single subject were quite constant. Inhibition of adherence was produced by several sugars, including the aminosugars mannosamine, glucosamine, and galactosamine. The pattern of inhibition produced by the sugars was similar for the two types of cells. Pretreatment of the yeast with mannosamine, followed by dilution to a subinhibitory concentration, produced some inhibition of yeast-buccal mucosal cell attachment, indicating some direct interaction between the sugar and the fungal cell. These data suggest that the mechanisms whereby C. albicans attaches to corneocytes and to buccal mucosal cells are probably similar.

Adhesiveness↗
PubMed1984

Scanning electron microscopy of bacteria adherent to intravascular catheters.

Scanning electron microscopy was used to assess the morphological features of coagulase-negative staphylococci adherent to polyvinylchloride intravascular catheter specimens. Clinical specimens were obtained by using patient catheters from which coagulase-negative staphylococci (greater than or equal to 15 colonies per catheter) grew on semiquantitative blood agar roll cultures. In vitro specimens were prepared by a previously published technique in which sterile polyvinylchloride catheters were immersed in 10(6) CFU of coagulase-negative staphylococci per ml suspended in phosphate-buffered saline. Unused sterile polyvinylchloride catheters were also examined. Scanning electron microscopy of unused sterile polyvinylchloride catheters demonstrated multiple linear surface irregularities. Scanning electron microscopy of infected patient catheters showed a diffuse amorphous material covering the entire surface and the presence of bacteria which appeared anchored to that surface by several different means. These included a slime layer, "foot" processes, and lodgement in surface irregularities. Scanning electron microscopy of in vitro specimens demonstrated no background surface coating, but it did show attachment of cocci to the surface by the same mechanisms as described for clinical specimens. These observations of similar means of attachment in clinical and in vitro specimens suggest that intrinsic catheter surface properties, bacterial surface features, and perhaps coating with host substances may all play a role in bacterial attachment to intravascular catheters. More sophisticated analysis of these interactions may clarify mechanisms of pathogenesis.

Adhesiveness↗
PubMed1984

Late-onset, warfarin-caused necrosis occurring in a patient with infectious mononucleosis.

A 25-year-old man with Klinefelter's syndrome and recurrent thromboplebitis , for which he had been receiving long-term warfarin sodium therapy, had bilateral ecchymoses on the hips coincident with serologically confirmed Epstein-Barr virus-caused mononucleosis. Biopsy specimens taken from the hip lesions showed microscopic findings consistent with a diagnosis of warfarin necrosis. Direct immunofluorescence microscopy disclosed vessel-wall deposition of IgM and heavy upper-dermal deposition of IgG. Electron microscopy disclosed nonspecific endothelial cell blebs that projected into the vessel lumen. The temporal association of mononucleosis with the onset of warfarin necrosis suggests that the viral illness may have precipitated an immunologic endothelial surface reaction, leading to thrombosis and secondary hemorrhage with infarction. To our knowledge, the appearance of warfarin necrosis in a patient receiving long-term, stable anticoagulation therapy has not been previously reported.

Adult↗
PubMed1983

In vitro quantitative adherence of bacteria to intravascular catheters.

Adapting standard techniques, a simple in vitro system was devised to compare quantitative bacterial adherence to iv catheters of different compositions. Upon brief immersion of catheters in suspensions of Staphylococcus aureus, coagulase-negative staphylococci, and Escherichia coli, organisms adhered to catheter surfaces. After overnight growth in broth, organisms remained adherent and formed colonies, as shown by light and scanning electron microscopy. In addition, quantitative adherence using a blood agar roll technique, expressed as bacteria per square centimeter of catheter surface area per 10(6) colonies per milliliter inoculum, was calculated. Adherence was greater on polyvinylchloride (PVC) catheters (geometric mean 342) than on Teflon catheters (geometric mean 49.6) for coagulase-negative staphylococci (P less than 0.005). Also, the number of coagulase-negative staphylococci adherent to PVC catheters was significantly greater than for E. coli (geometric mean 70.6) at analogous inocula (P less than 0.02). Differences in bacterial adherence to the surface of iv devices may be important in the pathogenesis of catheter-associated infections. This in vitro method could prove useful in testing bacterial adherence properties of newly developed catheter materials, and allow development of catheters less prone to be associated with bacterial adherence and catheter-related infections.

Adhesiveness↗
PubMed1983

Colonization of bacteria on polyvinyl chloride and Teflon intravascular catheters in hospitalized patients.

During an 8-month period all intravascular catheters were removed by sterile technique upon completion of use and submitted to the hospital microbiology laboratory. All catheters were routinely cultured by the semiquantitative culture technique, with greater than or equal to 15 colonies being defined as a positive result. Of the 687 Teflon catheters cultured, 6.9% were positive by culture, compared with 24.6% of 77 polyvinyl chloride catheters (P less than 0.001). Also, colonization of coagulase-negative staphylococci on polyvinyl chloride was more than on Teflon. These data suggest that polyvinyl chloride catheters are colonized more frequently with organisms than are Teflon catheters; additionally, there is an increased affinity of coagulase-negative staphylococci for polyvinyl chloride as compared with Teflon, substantiating our previous observations with an in vitro system. We conclude that the type of catheter material may be important in determining the incidence of catheter-related infections and in selective colonization by coagulase-negative staphylococci.

Bacterial Infections↗