Timothy R. Franson

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.

Prevalence survey of infections and their predisposing factors at a hospital-based nursing home care unit.

A prevalence survey was performed at a Veterans Administration nursing home care unit to detect the frequency, demographics, features, and potential risk factors associated with infections, compare different methods for calculating infection rates, and compare prevalence data with routine physician reporting of infections during a one‐month period. In 176 evaluable residents, 22 nursing home‐acquired infections were detected, with rates of 12.5% by infections per residents at risk, and 4.6% by infections per 1000 resident‐days. Fifty percent of these infections (11 of 22) involved the urinary tract, seven of which were associated with indwelling catheters. Factors potentially associated with increased overall infection rates included immobility (P < .02), acute‐care hospitalization in the 28 days preceding the study (P < .01), and antibiotics given preceding the infection (P < .001). An indwelling urinary catheter (P < .01) potentially was associated with an increased urinary tract infection rate. During the concurrent period, routine physician reporting of infection detected four of the 22 infections (18%) that were identified by the survey. These findings suggest that physician reporting of infection underestimates infection risk as compared with conventional surveillance practices, and that hospital‐based care units may have infection problems more similar to acute‐care hospitals than to community nursing homes. Identification of potential risk factors is critical in planning preventive practices based on institution‐specific needs.

Serial Bilirubin Determinations as a Prognostic Marker in Clinical Infections

Patients with documented serious infection and total bilirubin values of greater than 2 mg/dl were surveyed for serial changes in bilirubin and other laboratory and clinical features. Of 19 patients studied, 12 (Group A) had persisting or increasing hyperbilirubinemia, and 7 (Group B) had decline in bilirubin after infection onset. None demonstrated marked changes in other liver tests. Only one patient had infection directly involving the hepatobiliary system. There were no significant differences between the two groups with respect to underlying illnesses, active hepatobiliary diseases, pathogens, bacteremia, or administration of cholestatic drugs. All Group A patients died because of uncontrolled infections, whereas all Group B patients survived with resolution of infection (p less than .001). Ten of 15 patients with available preinfection liver tests demonstrated serial bilirubin increases without marked changes in other liver tests prior to clinical recognition of infection. These findings demonstrate that hyperbilirubinemia disproportionate to increases in other tests may manifest before recognition of infection and that persistent or progressive hyperbilirubinemia is indicative of ongoing active infection.

Documentation and Evaluation of Fevers in Hospital-Based and Community-Based Nursing Homes

We reviewed clinical evaluation practices and documentation of fever (greater than or equal to 100.2 degrees F) in all febrile patients over a two-month period in a hospital-based nursing home (HBNH) compared with a community-based nursing home (CBNH). Results showed 38 febrile (mean 101.9 degrees F) HBNH patients and 26 febrile (mean 101.5 degrees F) CBNH patients. Median time from fever onset to physician contact was 4 hours in HBNH and 12.5 hours in CBNH episodes (P less than 0.01). Laboratory studies were initially performed in 68% of HBNH and 31% of CBNH episodes (P less than 0.005), and diagnosis of fever source was documented in 76% of HBNH and 16% of CBNH episodes (P less than 0.005). Overall assessment stratification showed 81% febrile HBNH patients had both evaluation and therapy performed compared with 38% in CBNH (P less than 0.0001); 39% of febrile CBNH patients had no evaluation or therapy performed. Results indicate lack of documentation, and fever evaluation in CBNHs may preclude complete detection of nursing home-acquired infections and thereby hamper preventive responses to potential infection problems.

Recurrent granulomatous synovitis due to Mycobacterium kansasii in a renal transplant recipient

A 61-year-old woman received a cadaveric renal transplant in 1972 and was maintained on chronic immunosuppression. Nonspecific granulomatous synovitis of the left hand developed in 1982. After recurrence of synovitis in 1984, surgical exploration of the left hand demonstrated rice bodies in a region of chronic synovitis from which Mycobacterium kansasii was isolated. Despite therapy with isoniazid, rifampin, and ethambutol, to which the organism was susceptible in vitro, synovitis recurred. Recovery was completed after extensive synovectomies, decreased immunosuppression, and 24-months of therapy, with the drugs listed above; there was no evidence of mycobacterial infection at sites other than the left hand at any time. The occurrence of persistent Mycobacterium kansasii infection is distinctly unusual even in transplant recipients. In patients refractory to conventional antituberculous therapy, surgical management should be considered as an important therapeutic component.

Adherence of microorganisms to breast prostheses: an in vitro study.

The quantitative and morphological characteristics of microbial adherence of four organisms—Staphylococcus epidermidis, S. aureus, Escherichia coli and Candida albicans—to the surfaces of different breast prostheses were observed. Semiquantitative adherence studies based on a modification of Makis roll culture technique even after short contact times showed (1) increased microbial adherence at higher concentrations of the organisms and (2) differences in adherence properties between gram-positive bacteria and other organisms tested, noted also at lower organism concentrations. Scanning electron microscopy (SEM) to identify microorganisms on foam-covered prostheses, however, revealed organisms in the interstitial spaces that were not recovered by the plating technique. Other features on SEM were extracellular “slime” produced by S. epidermidis, which appears to act as a cement by which bacteria are held against prosthetic surfaces. These in-vitro findings suggest that brief exposure of the prostheses to a few organisms, particularly gram-positive bacteria, at the time of implantation would be sufficient inoculum for bacterial adherence to prosthetic surfaces.

Comparison of methods for calculation and depiction of incidence infection rates in long-term care facilities

Assessment of changes in endemic infections in health care facilities are often based on comparison of infection rates over time. This study compared two methods for calculating and depicting infection data at a hospital-based nursing home care unit. Prospective incidence surveillance of nursing home acquired infections was conducted over a 12-month period, during which time denominator information on census and patient care days was also collected. Monthly infection rates were calculated based on (a) census (number infections per month/average monthly census), and (b) care duration (number infections per month/average monthly resident stay days). Results showed average monthly infection incidence of 27.4 episodes, (range 19-37), with average monthly census of 166.2 (range 160.0-180.0) and average monthly patient days of 5056 (range 4631-5583). The average census based monthly infection rate was 16.5 (range 11.9-22.4); average care duration based monthly infection rate was 5.4 (range 3.8-7.2) episodes per 1000 patient care days. Results indicate care duration based rates demonstrate less marked rate fluctuation than census based findings, and that duration based rates are more similar to values observed in acute care hospital nosocomial infection rates, thus are less likely to be misunderstood or misinterpreted by staff. Institutions should consider analyzing their methods for depicting infection data to provide consistency and clarity in data reporting.

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.

Survey of nursing personnel attitudes toward infections and their control in the elderly

To better understand nursing practice in geriatric care settings as it relates to infections, a survey of nursing attitudes about a variety of infection control issues was undertaken. Nurses were recruited from four settings: a university-affiliated, private nursing home (N = 46), a hospital-based nursing home (N = 33), a private nursing home (N = 20), and a home care agency (N = 26). The nurses appropriately recognized the importance of pneumonia and influenza as major threats to health in these settings and also reported some indifference regarding the notification of physicians about fevers under 38.9 degrees C (102.0 degrees F). Among the groups, similar attitudes about infection control principles were recorded, except that the ratings by the home care agency nurses were different from those of the institution-based nurses in the following areas: isolation as a means to prevent infection spread, proper waste disposal methods, and frequency of catheter change. Assessment of personnel attitudes and practices are important in detecting problems, guiding in-service programing, and revising care practices.

Therapeutic Antibiotic Selection and Monitoring: A Comprehensive Management Protocol

Appropriate selection of antibiotics for patients and effective therapeutic monitoring is dependxad ent on a variety of factors. All health care perxad sonnel involved in drug selection and monitoring must first have a clear understanding of an individual patients health status. Furthermore, knowledge of the approprixad ate indications for and characteristics of the antimixad crobial agents available for selection and knowledge of anticipated clinical response, as well as potential drug complications, are necessary in order to achieve successxad ful patient management. Guidelines that address the interplay of the above factors in comprehensive fashxad ion are not generally available, and may receive less attention in health care teaching programs than discusxad sion of individual antibiotics and use for specific disxad ease states in isolated fashion. Furthermore, selection and monitoring practices may be strongly influenced by preferences of mentors and guest lecturers for specific agents, as well as by pharmaceutical advertising that may stress empiric drug selection (i .e. , drug selection