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Biomedical subjects

R P Wenzel

Publications and source records attributed to R P Wenzel.

At least 253 records · Page 14Linked to original sources

In vitro activity of N-formimidoyl thienamycin and other beta-lactam antibiotics against methicillin-resistant Staphylococcus aureus.

Of 43 isolates of methicillin-resistant Staphylococcus aureus, 90% were inhibited by 8 micrograms or less of N-formimidoyl thienamycin per ml by the agar-dilution technique. Cefamandole, cefotaxime, cefoperazone, moxalactam, and cefsulodin showed relatively poor activity. Vancomycin was the most active compound by weight, inhibiting 93% of strains at 1 microgram/ml.

Anti-Bacterial Agents↗

Epidemiology of nosocomial infections caused by methicillin-resistant Staphylococcus aureus.

Outbreaks of hospital-acquired infections caused by methicillin-resistant Staphylococcus aureus are being recognized with increasing frequency in the United States. Two thirds of outbreaks have been centered in critical care units. Infected and colonized inpatients appear to be the major institutional reservoir, and transient carriage on the hands of hospital personnel appears to be the most important mechanism of serial patient-to-patient transmission. In over 85% of hospitals into which they have been introduced, methicillin-resistant strains of S. aureus have become established as endemic nosocomial pathogens. A program designed to control a widespread outbreak in a university hospital used three surveillance methods to identify the major institutional reservoir of colonized and infected inpatients. Daily clinical laboratory surveillance, monthly prospective microbiology surveys of high-risk inpatients, and the recognition of previously infected 38%, 31%, and 31% of new cases, respectively. After control measures were instituted, the prevalence (p less than 0.001) and the number of acquisitions (p less than 0.002) of methicillin-resistant S. aureus declined over a 12-month period.

Burns↗

Relation between surgical volume and incidence of postoperative wound infection.

We used a statewide program for the surveillance and reporting of infections acquired in the hospital to examine the relation between volume of surgery and the incidence of postoperative wound infection. Over a 29-month period 25,941 surgical procedures performed at 22 hospitals were studied. For all procedures studied, the mean number of operations performed was directly related to hospital size (number of beds). A highly significant inverse relation was found between the logarithm of the frequency of operation and the infection rate for appendectomy, herniorrhaphy, cholecystectomy, colon resection, and abdominal hysterectomy. (The relation was borderline [P = 0.055] for laminectomy and not significant for cesarean section.) Although these data clearly demonstrate higher morbidity in hospitals performing relatively little surgery, there are several possible explanations, and no conclusions for health policy can yet be drawn.

Data Collection↗

Methicillin-resistant Staphylococcus aureus: microbiologic characteristics, antimicrobial susceptibilities, and assessment of virulence of an epidemic strain.

An epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) isolated from patients at the University of Virginia Hospital in Charlottesville (MRSA-Va) was characterized, and virulence properties were compared with those of three clinically significant strains of methicillin-sensitive S. aureus. Unlike most known strains of MRSA, MRSA-Va was sensitive to tetracycline and streptomycin and exhibited high-level homogeneous methicillin resistance (minimal inhibitory concentration, greater than 128 microgram/ml). The expression of resistance was not influenced by incubation temperature. MRSA-Va contained significantly more catalase (P less than 0.05) than methicillin-sensitive strains but about the same amount of protein A. Phagocytosis and killing of MRSA-Va by normal polymorphonuclear leukocytes were not significantly different from that of the Wood-46 strain of S. aureus. In mouse virulence studies using both intraperitoneal and intravenous modes of infection, 50% lethal doses for MRSA-Va were comparable with those of the three methicillin-sensitive strains. This epidemic strain of MRSA appears to be fully virulent.

Animals↗

Nosocomial bloodstream infections in a newborn intensive care unit: a case-matched control study of morbidity, mortality and risk.

Routine surveillance of 1252 newborns admitted over a four-year period to a newborn intensive care unit (ICU) identified 49 (4%) with nosocomial bloodstream infections. Forty-nine control subjects without such infections were selected, matching for birth weight, gestational age, and at least three diagnoses per patient. Overall, 27% of cases and 6% of controls died (p = 0.01) and significant differences persisted when cases with multiple bloodstream infections were removed from analysis. Although small numbers of case-control pairs remained for analysis, significant differences disappeared when cases with multiple bloodstream infections plus case-control pairs discordant for presence/absence of nosocomial infections at other sites were eliminated from comparison. On the average, all cases and controls were hospitalized for 70 +/- 14 days and 50 +/- 8 days, respectively, but when cases with multiple bloodstream infections or the multiple bloodstream infections-discordant pair group were removed from analysis, the significant difference in hospitalization disappeared. A strong association between nosocomial infections at sites other than the bloodstream and bloodstream infections was demonstrated and may suggest a means of reducing the incidence of bloodstream infections in a high risk population.

Bacterial Infections↗

Endometritis following cesarean section. A controlled study of the increased duration of hospital stay and direct cost of hospitalization.

The increased hospital stay and direct costs of hospitalization as a result of postcesarean section endometritis were evaluated in a case-matched and controlled study (N = 20 in each group). Endometritis increased postcesarean section hospital stay by 3 days and increased hospital cost by $850. Fifteen to 20% of women delivered by cesarean section develop postpartum endometritis. The success of future antibiotic or surgical intervention studies in reducing this high complication rate can be more accurately evaluated by comparison with these now established parameters of morbidity and cost.

Adult↗

Postoperative wound infection rates: results of prospective statewide surveillance.

The results of a prospective statewide study of postoperative wound infection rates after 19 selected surgical operations are reported. Rates are based on 44,689 operations performed at 38 hospitals from January 1, 1977 through May 31, 1979. The data were collected by review of ward charts and are compared with those of earlier reports. Particularly high rates of infection were found after surgery for perforative appendicitis, colorectal resection, radical neck dissection and leg amputations. These rates should serve as a baseline for future comparisons. The potential value of centralized infection reporting is discussed.

Hospital Bed Capacity, 100 to 299↗

Catheter-associated urinary tract infections in surgical patients: a controlled study on the excess morbidity and costs.

The increased hospital stay and excess hospitalization costs that resulted from Foley catheter-associated urinary tract infection after 5 common surgical procedures were evaluated in a case-matched and controlled study. Nosocomial urinary tract infections increased postoperative hospital stay by an average of 2.4 days (p equals 0.017) and increased hospital costs by $558 per patient. Recommendations for prevention of urinary catheter-associated infections can be assessed accurately by comparison to the parameters of morbidity and cost.

Cost Control↗

Methicillin-resistant Staphylococcus aureus: introduction and spread within a hospital.

In March 1978, a strain of methicillin-resistant Staphylococcus aureus was introduced from the community into a university hospital. Within 6 months of admission of the index case, methicillin-resistant S. aureus was isolated from 30 additional patients, 22 of whom were epidemiologically linked by a common phage type (6/47/54/75/83A) and roommate-to-roommate spread. Sixteen of 31 cases were infected, six with bacteremia. Patients with infections received cephalosporins more frequently before infection than did control subjects (p < 0.05). Patients acquiring methicillin-resistant S. aureus in the intensive care unit had a longer mean stay, had higher overall mortality, and received nafcillin and aminoglycosides more frequently than did cohorted control subjects. By mid-1979, methicillin-resistant S. aureus accounted for 38%, 31%, and 24% of all nosocomial S. aureus postoperative wound, pulmonary, and bloodstream infections, respectively. In hospitals with significant methicillin-resistant S. aureus isolation rates, initial empiric therapy of presumed S. aureus infection with vancomycin seems warranted.

Adult↗

Serratia marcescens bacteremia from contaminated pressure transducers.

Primary Serratia marcescens bacteremia developed in 17 patients in an intensive care unit after exposure to pressure monitoring devices. A study showed that all of the transducer heads were contaminated with S marcescens, and prospective culturing of 110 pressure monitoring lines disclosed a 24% rate of contamination with the same organism. Hand contamination occurs at the time the equipment is initially assembled; in five of eight trials, transmission was shown experimentally to occur by direct inoculation of open ports. Routine disinfection of the transducer heads with glutaraldehyde not only effectively decontaminated all pressure monitoring lines in use, but also controlled the outbreak.

Enterobacteriaceae Infections↗

Enhanced isolation of Mycoplasma pneumoniae from throat washings with a newly-modified culture medium.

Two hundred throat washings, previously screened and presumed negative for Mycoplasma pneumoniae in conventional mycoplasma culture media, were retested for the organism in a modified medium (PS-4) initially developed for cultivation of a tick-derived Mycoplasma (spiroplasma). The organism was rapidly identified with an agar plate immunofluorescence procedure. M. pneumoniae was isolated from 69 (34.5%) of the 200 "negative" specimens cultured on a diphasic SP-4 medium, in contrast to 10 isolations (5%) made on conventional diphasic mycoplasma medium. This enhanced recovery of M. pneumoniae represented a combination of a superior culture medium and a more efficient identification technique. The findings suggest that these procedures might be effectively applied to the recovery of M. pneumoniae from all likely host and that improved recovery of the organism may aid in the interpretation of a number of puzzling questions about the epidemiology of M. pneumoniae infections.

Adult↗

Development of a statewide program for surveillance and reporting of hospital-acquired infections.

In 1974, a statewide program was begun to improve surveillance of nosocomial infection in Virginia hospitals. Infection control practitioners were trained at the University of Virginia Hospital, Charlottesville, and were encouraged to submit monthly surveillance reports for analysis. In the first three years of the project, 141 students from 65 hospitals within the state attended a two-week basic course, with eight to 10 students per class. Of the 98 Virginia hospitals that sent students, 75 (73%) submitted monthly reports. The consistency of reporting (number of monthly reports received divided by the number of possible reporting months) was 83%. The sensitivity of reported data was estimated in comparative daily prospective surveys to be 69% for participating hospitals, and the specificity was 99%. The crude infection rate for the first 1.1 million patients at risk was 3.3%.

Cross Infection↗

Hospital-associated candiduria: predisposing factors and review of the literature.

A series is presented of 98 patients with hospital-acquired candiduria identified by continual nosocomial infection surveillance. Analysis of the differences between case-matched controls and 20 patients indicated that there were significant increases in the duration of prior Foley catheterization (12 versus 6 days), length of time on multiple antibiotics (16 versus 7 days) and length of total hospitalization of the infected group. Review of the infected patients' charts showed that the indications for bladder catheterization and use of antibiotics were usually explicitly stated and considered valid. The English literature on primary Candida urinary tract infections is reviewed and future approaches to the problem are summarized.

Adolescent↗