Louise M. Dembry

A Decade of Prevalence Surveys in a Tertiary-Care Center: Trends in Nosocomial Infection Rates, Device Utilization, and Patient Acuity

OBJECTIVE To evaluate the usefulness of repeated prevalence surveys to determine trends in the rates of nosocomial infections and to detect changes in risk factors (e.g., use of invasive devices) associated with nosocomial infections. PATIENTS AND METHODS Ten annual prevalence surveys were conducted by trained infection control practitioners between 1985 and 1995 for acute-care patients on the medical, surgical, pediatric, and obstetric-gynecologic services at a 900-bed, tertiary-care, teaching hospital with 750 acute-care beds. The same methods of chart review and concurrent reporting from nursing, the microbiology and clinical laboratory, and the pharmacy were used each year to collect data on the prevalence of nosocomial infections, invasive-device utilization, and abnormal laboratory indicators. Although data were collected on a single day, a period-prevalence study approach was used, because charts were reviewed for any infection data occurring within the 7 days prior to the survey. RESULTS The hospital census for acute care patients, as measured by the prevalence surveys, declined sharply over the 10 years, from 673 to 575 patients (P = .02). However, the medical service census increased from 150 to 188 patients (P = .01). During the same period, there was a significant decrease in the mean length of stay, from 7.3 to 6.0 days (P = .01), and a concomitant increase in the mean diagnosis related-group case-mix index, from 1.03 to 1.24 (P = .001). Overall, nosocomial infection rates remained unchanged over the study period (mean of 9.85 infections per 100 patients), but rates of nosocomial bloodstream infection increased from 0.0% in 1985 to 2.3% in 1995 (P = .05). Nosocomial infection rates were significantly higher on the medical and surgical services than on other services (P<.001). Utilization rates increased significantly for Foley catheters (9.0% to 16.0%, P = .002) and ventilators (5.0% to 8.0%, P = .05). CONCLUSIONS Despite apparent increases in the severity of illness of our patients, overall rates of nosocomial infection remained stable during a decade of study. Rates of nosocomial bloodstream infection increased, in parallel with National Nosocomial Infection Surveillance System data. We found repeated prevalence surveys to be useful in following trends and rates of infection, device utilization, and abnormal laboratory values among patients at our institution. Such methodologies can be valuable and low-cost components of a comprehensive infection surveillance, prevention, and control program and other potential quality-improvement initiatives, because they enable better annual planning of departmental strategies to meet hospital needs.

SHEA Guideline for Management of Healthcare Workers Who Are Infected with Hepatitis B Virus, Hepatitis C Virus, and/or Human Immunodeficiency Virus •

This guideline provides the updated recommendations of the Society for Healthcare Epidemiology of America (SHEA) regarding the management of healthcare providers who are infected with hepatitis B virus (HBV), hepatitis C virus (HCV), and/or the human immunodeficiency virus (HIV). For the reasons cited in the guideline, SHEA continues to recommend that, although some aspects of the approach to and administrative management of each of these infectious syndromes in healthcare providers are similar, separate management strategies for healthcare workers who are infected with these unrelated viruses remain appropriate. As we did in both prior iterations of this document, SHEA emphasizes the use of appropriate infection control procedures to minimize exposure of patients or providers to blood, emphasizes that transfers of blood from patients to providers and from providers to patients should be avoided, and recommends that infected healthcare providers should not be totally prohibited from participating in patient-care activities solely on the basis of a bloodborne pathogen infection. The types of procedures assessed by the panel as associated with an increased risk for provider-to-patient transmission of these pathogens are discussed in detail. For each pathogen, recommendations are graduated according to the relative viral load level of the infected provider (Tables 1 and 2). However, SHEA emphasizes that, because of the complexity of these cases, each such case will be slightly different from the next, and each should be independently considered in context.

Molecular typing demonstrating transmission of gram-negative rods in a neonatal intensive care unit in the absence of a recognized epidemic.

Molecular typing techniques have been used in outbreak investigations. In this study, molecular typing techniques were used to track the spread of gram-negative rods (GNRs) in a neonatal intensive care unit (NICU) in the absence of an outbreak. Stool or rectal swab cultures for GNRs were obtained from all infants on admission, weekly, and on discharge. GNRs were tested for gentamicin susceptibility and were typed by contour-clamped homogeneous electric field electrophoresis. Transmission of identical strains of GNRs among infants was noted. Shared strains were more gentamicin resistant compared with unique strains (53% vs. 10%; P=.0001). Infants first colonized when they were >1 week of age had more total days of antibiotic treatment and had a higher rate of acquiring a shared and gentamicin-resistant strain, compared with infants colonized earlier. Antibiotic use increases colonization of infants in the NICU with resistant and shared strains of GNRs.

Control of endemic glycopeptide-resistant enterococci

OBJECTIVE To evaluate the epidemiology of, and control measures for, vancomycin-resistant Enterococcus (VRE) in a renal unit. DESIGN A 3-month, prospective, prevalence culture survey of patients on a 24-bed renal unit. SETTING A 975-bed community teaching hospital. PATIENTS Patients admitted to the renal unit over a 3-month period. Patients identified with VRE were each matched with four patients without VRE isolated over the study period. INTERVENTIONS/CONTROL MEASURES: Resistant-organism barrier precautions. To eradicate carriage of VRE, two patients with VRE stool colonization were treated with 5 days of oral doxycycline (100 mg twice per day) and rifampin (300 mg/day). RESULTS Seven patients with VRE (8 isolates) were identified. Five isolates were Enterococcus faecium (vancomycin MIC = 16 to 256 micrograms/mL), two were Enterococcus faecalis (MICs = 16 and 124 micrograms/mL), and one was Enterococcus gallinarum (MIC = 8.0 micrograms/mL). Eradication of carriage with VRE was accomplished in two patients treated with doxycycline and rifampin. In the final 30 days of the culture survey and at 9 months, there were no further patients with VRE identified. CONCLUSIONS Resistant-organism precautions and elimination of patient carriage may be useful measures for controlling the spread of low-prevalence endemic vancomycin-resistant Enterococcus.

Antimicrobial Activities of BMS-284756 Compared with Those of Fluoroquinolones and β-Lactams against Gram-Positive Clinical Isolates

ABSTRACT The in vitro antibacterial activity of BMS-284756 was compared to those of ciprofloxacin, gatifloxacin, moxifloxacin, ceftriaxone, imipenem, piperacillin-tazobactam, and amoxicillin-clavulanic acid against 492 gram-positive clinical isolates. BMS-284756 was the most-active agent against Streptococcus pneumoniae, Streptococcus viridans, beta-hemolytic streptococci, methicillin-sensitive and -resistant Staphylococcus aureus, methicillin-sensitive and -resistant coagulase-negative staphylococci, and enterococci.

Reasons Physicians Accepted or Declined Smallpox Vaccine, February Through April, 2003

From February to April 2003, we performed an e-mail-based survey to assess responses of physicians at Yale University to being offered smallpox vaccine. Of 58 respondents, 3 (5%) had been or intended to be vaccinated. Reasons cited for declining vaccination included: belief that benefits did not outweigh risks (55%), belief that the vaccination program was unnecessary (18%), desire to wait and see what side effects occurred in vaccinees (11%), and worries about compensation or liability (7%). Most (94%) considered risks to themselves, family, or patients in their decision. Only 3% thought a smallpox attack in the next 5 years was likely or very likely. Physicians did not accept the smallpox vaccine because they did not believe the potential benefits were sufficient.

Clinical and Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in a Neonatal Intensive Care Unit in the Decade following Implementation of an Active Detection and Isolation Program

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent source of infection in the neonatal intensive care unit (NICU), often associated with significant morbidity. Active detection and isolation (ADI) programs aim to reduce transmission. We describe a comprehensive analysis of the clinical and molecular epidemiology of MRSA in an NICU between 2003 and 2013, in the decade following the implementation of an MRSA ADI program. Molecular analyses included strain typing by pulsed-field gel electrophoresis, mec and accessory gene regulator group genotyping by multiplex PCR, and identification of toxin and potential virulence factor genes via PCR-based assays. Of 8,387 neonates, 115 (1.4%) had MRSA colonization and/or infection. The MRSA colonization rate declined significantly during the study period from 2.2 to 0.5/1,000 patient days (linear time, P = 0.0003; quadratic time, P = 0.006). There were 19 cases of MRSA infection (16.5%). Few epidemiologic or clinical differences were identified between MRSA-colonized and MRSA-infected infants. Thirty-one different strains of MRSA were identified with a shift from hospital-associated to combined hospital- and community-associated strains over time. Panton-Valentine leukocidin-positive USA300 strains caused 5 of the last 11 infections. Staphylococcal cassette chromosome mec (SCCmec) types II and IVa and agr groups 1 and 2 were most predominant. One isolate possessed the gene for toxic shock syndrome toxin; none had genes for exfoliative toxin A or B. These results highlight recent trends in MRSA colonization and infection and the corresponding changes in molecular epidemiology. Continued vigilance for this invasive pathogen remains critical, and specific attention to the unique host, the neonate, and the distinct environment, the NICU, is imperative.

Comparison of In Vitro Activity of Trovafloxacin Against Gram-positive and Gram-negative Organisms with Quinolones and β-Lactam Antimicrobial Agents

The in vitro activity of trovafloxacin against 721 Gram-negative and 498 Gram-positive organisms was determined by the standard microdilution broth method using commercially prepared frozen microtiter plates. The activity of trovafloxacin was compared to ofloxacin, ciprofloxacin, amoxicillin/clavulanate, ampicillin/sulbactam (1:1), piperacillin/tazobactam, ceftriaxone, and imipenem. Trovafloxacin had equal or greater activity compared with the other agents tested against Citrobacter diversus, Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Haemophilus influenzae, Stenotrophomonas maltophilia, Serratia marcescens, staphylococci, Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus viridans, group G streptococci, Enterococcus faecalis, and E. faecium. The reliability of the commercially prepared plates for testing the in vitro activity of the quinolones was evaluated by comparing identical isolates also tested by broth microdilution using laboratory prepared plates. The commercially prepared plates generally correlated, within one- to twofold dilutions, with the laboratory prepared plates. There was, however, a large discrepancy obtained when testing Enterobacter agglomerans and E. cloacae, where the commercially prepared plates yielded a significantly higher MIC90 value.

Comparative antimicrobial activity of gatifloxacin with ciprofloxacin and beta-lactams against gram-positive bacteria

Gatifloxacin is a new 8-methoxy fluoroquinolone. The in-vitro antibacterial activity of gatifloxacin was compared to that of ciprofloxacin, ceftriaxone, imipenem, piperacillin/tazobactam and amoxicillin/clavulanic acid against 165 streptococcal isolates, 369 staphylococcal isolates, and 50 enterococcal isolates recently recovered from clinical isolates. Gatifloxacin was the most active agent tested against streptococci including penicillin-nonsusceptible Streptococcus pneumoniae (MIC(90) 0.5 microg/mL). Imipenem and gatifloxacin (MIC(90) 0.5 microg/mL) were the most active agents tested against viridans group streptococci. All the agents demonstrated excellent activity against methicillin-susceptible S. aureus. Imipenem, piperacillin/tazobactam, amoxicillin/clavulanic acid, and gatifloxacin had good activity against methicillin-sensitive S. epidermidis. Among the methicillin-sensitive and methicillin-resistant coagulase-negative staphylococci tested, gatifloxacin was the most active agent. Amoxicillin/clavulanic acid and gatifloxacin were the most active agents against E. faecalis. Thus, gatifloxacin possesses equal or superior activity when compared to ciprofloxacin and beta-lactams making it a promising new fluoroquinolone for clinical use in treating Gram-positive infections.

The clinical and molecular epidemiology of pre-transplant vancomycin-resistant enterococci colonization among liver transplant recipients.

Vancomycin‐resistant enterococci (VRE) infections cause significant morbidity in liver transplant recipients. The epidemiology and impact of pre‐transplant colonization with VRE among patients who undergo liver transplantation are poorly understood. We conducted an observational cohort study to identify risk factors and outcomes associated with pre‐transplant VRE colonization and described the molecular diversity among VRE strains colonizing patients who undergo liver transplantation. Perirectal VRE surveillance cultures were performed prior to transplantation. Repetitive sequence‐based polymerase chain reaction (rep‐PCR) testing was used to identify clonality among VRE isolates. Of 61 patients who underwent pre‐transplant VRE surveillance and subsequent liver transplantation, 27 (44%) were colonized with VRE. In multivariate analysis, pre‐transplant VRE colonization was associated with central venous catheterization (OR 9.4, 95% confidence interval [CI]= 1.3–70.2, p = 0.03) and rifaximin use (OR 15.4, 95% CI 1.5–159.7, p = 0.02). Pre‐transplant VRE colonization was associated with more hospital days post‐transplant (26.6 vs. 16.1 d, p = 0.04). Of VRE‐colonized patients analyzed with rep‐PCR, 68% were colonized with the same strain as another patient in the cohort. Active surveillance identifies VRE‐colonized patients who may benefit from targeted antimicrobial prophylaxis and enhanced infection prevention measures to prevent VRE spread. The relationship between rifaximin receipt and VRE colonization warrants further study. The identification of similar VRE isolates may suggest linked transmission during pre‐transplant hospitalizations, which should be further investigated in prospective studies.