Heart failure is a leading cause of death in developed nations despite medical management. Cardiac transplantation is a potentially lifesaving intervention for approximately 4000 advanced heart failure patients per year; however, the demand for donor hearts far exceeds the supply. Ventricular assist devices provide temporary support for patients with severe heart failure until myocardial recovery occurs or a donor heart becomes available. For those ineligible for transplantation, ventricular assist devices may be used permanently and have demonstrated reduced mortality and an improved quality of life compared with continued medical therapy. Nonetheless, these devices are under-used, in part due to the frequency of complications. Device-related infections are one of the most frequent sequelae of ventricular assist device placement and occur in 18–59% of cases. Infections can involve any part of the device and confer substantial morbidity and mortality. Here, we provide an introduction to ventricular assist devices, explore the nature and pathogenesis of ventricular assist device-related infections, discuss problems with diagnosis, and present treatment and prevention strategies.

Background. Persons with acquired immune deficiency syndrome (AIDS) who use drugs appear to be at increased risk for colonization and infection with Staphylococcus aureus. Little is known about the nature of and risk factors responsible for this association. This study is among the first to prospectively follow carriage and infection in this uniquely high-risk population. Methods. We prospectively followed the cases of 75 patients with AIDS in a residential drug treatment facility and screened for S. aureus nasal colonization and infection. Results. Thirty-seven baseline cultures (49%) were positive for S. aureus, and 81% of subjects were colonized at least once during the study. Thirteen subjects experienced 17 infections. Pulsed-field gel electrophoresis and sequence-based typing methods revealed that 244 (92%) of the isolates belonged to either clonal type A or B. Clonal type A was methicillin-susceptible. Clonal type B consisted of 3 main subtypes (B1, B2, and B3), all with the same allelic profile (ST8) and staphylococcal protein A gene (spa) type (7). Of note, subtype B1 was methicillin-susceptible (ST8 and spa type 7), lacking mecA, whereas the other B clones were methicillin-resistant. Both clones were resistant to trimethoprim-sulfamethoxazole. Clonal type B isolates were relatively resistant, suggesting prior exposure to the health care setting. Conclusions. This study demonstrates a sustained high rate of S. aureus carriage and infection. It demonstrates the capacity of unique methicillin-resistant S. aureus clones with an established linkage to earlier outbreaks of methicillin-resistant S. aureus, as well as to human immunodeficiency virus—infected subjects, to persist in this residential setting. It also illustrates the apparent genetic instability or transmissibility of the staphylococcal chromosomal cassette mec type IV element.

AbstractObjective:To evaluate the relationship betweenStaphylococcus aureusnasal and tracheal colonization and infection in medical intensive care unit (MICU) patients. The primary outcome was the incidence ofS. aureusinfection in colonized versus non-colonized patients.Design:Prospective, observational cohort study. Patients admitted to the MICU during the study period were screened forS. aureusnasal and tracheal colonization by culture and a PCR assay twice weekly. Demographic, clinical, and microbiologic data were collected in the MICU and for 30 days after discharge. PFGE and antibiotic susceptibility testing were performed on allS. aureusnasal, tracheal, and clinical isolates.Results:Twenty-three percent of patients (47 of 208) were nasally colonized withS. aureus. Twenty-four percent of these patients developedS. aureusinfections versus 2% of noncolonized patients (P< .01). Nine of 11 patients with both nasal colonization and infection were infected by their colonizing strain. Two of 47 nasally colonized patients developed an infection with a different strain ofS. aureus. Fifty-three percent of intubated patients with nasal colonization (10 of 19) had tracheal colonization withS. aureusas opposed to 4.9% of intubated, non-colonized patients (3 of 61) (P< .01). Parenteral antibiotics were ineffective at clearing nasal colonization. PCR detectedS. aureuscolonization (nasal and tracheal) within 6.5 hours with a sensitivity of 83% and a specificity of 99%.Conclusions:The incidence ofS. aureusinfection was significantly elevated in nasally colonized MICU patients. Techniques to rapidly detect colonization in this population may make targeted topical prevention strategies feasible. (Infect Control Hosp Epidemiol 2005;26:622-628)

ABSTRACT It is unclear whether the levels of Staphylococcus aureus colonization of hospital personnel with patient exposure are increased or whether personnel become colonized with more antibiotic-resistant strains. Differences in nasal and hand carriage of S. aureus between medical and nonmedical hospital personnel were examined. No differences in nasal carriage between the two groups were found; however, there was a trend that suggested differences in the rates of hand carriage of S . aureus (18% of nonmedical personnel and 10% of medical personnel). Medical personnel were colonized with more antibiotic-resistant isolates than nonmedical personnel (mean, 2.8 versus 2.1 isolates [ P < 0.03]), and the strain profiles indicated that they tended to be more clonal in origin, suggesting that exposure to hospital isolates alters the colonization profile.

Drug users have a higher incidence of colonization with Staphylococcus aureus than does the general population, and, as a result, they are at increased risk of infection with their colonizing strain. The purpose of this study was to examine the role of drug-use risk networks in S. aureus transmission, the similarity of S. aureus isolates within these networks, and the possible role of inhalation drug use paraphernalia in the transmission of S. aureus. Strains of S. aureus are shared among colonized inhalation drug users within drug-use risk networks. It suggests that patterns of drug use and the geographic location where drug sharing occurs are major contributors to the transfer of staphylococci and, as a result, to the high prevalence of staphylococcal colonization and perhaps disease in this population.