Infections associated with ventricular assist devices: epidemiology and effect on prognosis after transplantation.

BACKGROUND: Ventricular assist devices (VADs) can be used as a bridge to orthotopic heart transplantation (OHT) in people with severe congestive heart failure. Although they can be inserted for an indefinite time period (unlike balloon pumps), they do carry a substantial risk of infection. We studied the epidemiology, microbiology, and consequences of infection in patients with VADs who ultimately had cardiac transplantation. METHODS: Records of VAD-supported patients at our institution between January 1995 and January 2005 were identified by ICD-9 code. Infection was classified as driveline infection, pocket infection, mediastinitis, or VAD endocarditis in increasing severity of illness. RESULTS: Of 73 patients identified by ICD-9 code, 60 had charts available for review. Of these 60, 72% had a VAD infection: 13 had VAD endocarditis; 3, mediastinitis; 25, pocket infection; and 29, driveline infection. The only association of infection (43 patients, 72%) and demography or underlying disease was that of endocarditis with older age (median age 59 vs. 53 years; P=0.02) and diabetes mellitus (13 patients, 30%; risk ratio 3.4; P=0.01). The duration of VAD support was longer in infected patients (median 125 days) vs. uninfected ones (25 days). Median survival measured from the time of VAD placement (although also true from the time of transplantation) was shorter in patients with VAD endocarditis (120 days) and pocket infection (350 days) vs. no infection (>2400 days) with a significant P=0.017 for endocarditis. Four patients had infections after transplantation that were caused by the same organism as their VAD infection. The predominant pathogens in VAD infection were Staphylococcus and Enterococcus spp. CONCLUSION: VAD use as a bridge to cardiac transplantation is associated with a large number of device-related infections. Patients with infected VADs, on average, wait longer for transplantation than patients with uninfected VADs, and patients with VAD endocarditis have a shorter survival than patients with no VAD infection or simple driveline infection.

Infective endocarditis following orthotopic heart transplantation: 10 cases and a review of the literature.

BACKGROUND: Infective endocarditis is a known complication of cardiac transplantation. However, published information has been limited to case reports and small case series. METHODS: Cardiac transplantation has been performed at Temple University Hospital since 1983. We identified transplant patients with ICD-9 codes for endocarditis or bacteremia. A diagnosis of endocarditis required fulfillment of the Duke criteria and presence of a vegetation. Clinical and microbiologic data were collected. Demographic and survival information were compared with heart transplant recipients without endocarditis. We reviewed all previously published cases using a MEDLINE search. RESULTS: Ten of 659 heart transplant recipients had endocarditis (1.5%, 187 cases per 100,000 person years). Mitral and tricuspid valves were involved predominantly. No patient had aortic valve infection. Patients with tricuspid valve infection had a greater median number of endomyocardial biopsies (n=23) than those with mitral valve infection (n=9, P=0.10). The major pathogens were Staphylococcus aureus (4 cases) and Aspergillus fumigatus (3 cases). Factors associated with S. aureus infection were new hemodialysis catheters, cellulitis, and a contaminated donor organ. All patients with A. fumigatus had antecedent cytomegalovirus viremia and disseminated fungal infection, including endophthalmitis. Endocarditis-related mortality was 80%. Median survival after transplant was 1.4 years in patients with endocarditis, compared with 9.3 years in other heart transplant recipients (P<0.001). CONCLUSIONS: Endocarditis is substantially more common in heart transplant recipients than in general populations. Frequent central venous catheter access and multiple endomyocardial biopsies appear to predispose to infection. Aspergillus is a common pathogen and endocarditis follows infection elsewhere. The prognosis of post-cardiac transplant endocarditis is poor.

External cooling in the management of fever.

Although physical methods of cooling are the treatment of choice for hyperthermia, their value in the treatment of fever remains uncertain. Methods involving convection and evaporation are more effective than those involving conduction for the treatment of hyperthermia. These same methods, combined with antipyretic medication, are preferable to immersion as treatment for fever in young children but are generally not practical in adults. Febrile children treated with tepid-water sponging plus antipyretic drugs are more uncomfortable that those treated with antipyretic drugs alone, although they exhibit slightly more rapid reductions in temperature. When febrile, seriously ill patients are externally cooled and are sedated or paralyzed with drugs that suppress shivering, they may have a more rapid reduction of fever and reduced energy expenditure than if treated with antipyretic drugs alone. A risk/benefit assessment of the consequences of such treatment is not yet possible.

Use and effectiveness of hypothermia blankets for febrile patients in the intensive care unit.

We performed a prospective observational (noninterventional) study of hypothermia blanket use in a population of adult intensive care unit patients with body temperatures of > or = 102.5 degrees F. Thirty-nine of ninety-four febrile episodes (in 83 patients) were treated with hypothermia blankets. Logistic regression revealed that the strongest independent predictors of hypothermia blanket use were a temperature of > or = 103.5 degrees F (odds ratio [OR] = 17), mechanical ventilation (OR = 25), and acute central nervous system illness (OR = 7.5). Hospitalization in the medical intensive care unit was strongly associated with avoidance of this therapy (OR = 0.023). Treatment with a hypothermia blanket was ordered by a physician in only 15% of cases. The mean cooling rate was the same (0.028 degree F/h) for blanket-treated and control patients. Multivariate Cox regression and factorial and repeated measures of analysis of variance revealed that blanket treatment was not more effective than other cooling methods. However, this treatment was associated with more "zigzag" temperature fluctuations of > or = 3 degrees F (56% of blanket-treated patients vs. 18% of control patients; P < .001) and rebound hypothermia (18% vs. 0; P = .001). Hypothermia blanket therapy is primarily a nursing decision. We conclude that in addition to being no more effective than other cooling measures, hypothermia blanket therapy was associated with more temperature fluctuations and with more episodes of rebound hypothermia.

Comparative susceptibilities of Klebsiella species, Enterobacter species, and Pseudomonas aeruginosa to 11 antimicrobial agents in a tertiary-care university hospital.

The in vitro activity of cefepime was compared versus that of 10 antimicrobial agents commonly used in the treatment of serious infections caused by common aerobic gram-negative bacteria: aztreonam, cefoperazone, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, piperacillin, ticarcillin-clavulanic acid, and tobramycin. We tested 30 clinical isolates representing a cross section of Klebsiella and Enterobacter species and Pseudomonas aeruginosa collected at our tertiary-care university hospital. The most potent beta-lactams were imipenem and cefepime, which demonstrated significant activity against the majority of strains in all 3 genera of bacteria tested, as did ciprofloxacin and tobramycin. Ceftazidime was active against Pseudomonas aeruginosa but was less potent against Klebsiella and Enterobacter spp. Cefoperazone and ceftriaxone were less active than ceftazidime against Pseudomonas aeruginosa. Cefepime was found to be highly active against many resistant organisms that traditionally have been difficult to treat.

Infections complicating tunneled intraspinal catheter systems used to treat chronic pain.

Tunneled intraspinal catheters and catheter-pump systems are increasingly common treatments for severe chronic pain, but these long-term catheters have caused meningitis, epidural abscesses, and other serious infections. At a cancer referral center, 81 catheters were placed in 72 patients over a 7-year period. There were seven catheter-associated infections: two were meningeal (one was accompanied by an epidural abscess and one by a pocket infection and bacteremia), four were associated with a pocket, and one was associated with a tunnel. The infection rate was 0.77 per 1,000 catheter-days. Pathogenic organisms that were isolated were primarily normal skin flora. By multivariate Cox analysis, the only factor significantly associated with catheter infection was prolonged catheter placement surgery, i.e., a procedure lasting at least 100 minutes (RR, 8.8; 95% CI, 1.6-50). Three patients were cured by removal of the catheter and treatment with antibiotics, and symptoms were satisfactorily suppressed in four patients with antibiotics alone. Considering the severity of illness in catheter recipients, the infection rate was relatively low. Removal of the catheter does not appear mandatory when the goal is suppression of infection-related symptoms, especially when the infection has not spread to the CNS, the infecting organism has an intrinsically low virulence, and the infected patient is terminally ill.

Investigation of a pseudo-outbreak of orthopedic infections caused by Pseudomonas aeruginosa.

OBJECTIVE: To report a pseudoepidemic of Pseudomonas aeruginosa infections discovered during an investigation of postoperative joint infections. DESIGN: A retrospective review of case patients' hospital charts, operative reports, and laboratory data, as well as environmental culturing, polymerase chain reaction (PCR) ribotyping of outbreak isolates, and in vitro analysis of P aeruginosa growth characteristics. SETTING: A 510-bed, university-affiliated adult tertiary care hospital. RESULTS: Between October 1 and December 1, 1992, seven postsurgical joint infections were diagnosed, including four caused by P aeruginosa. A bottle of "sterile" saline used to process tissue specimens was found to be contaminated with P aeruginosa. Further investigation revealed that P aeruginosa had grown from seven additional tissue cultures, all of which had been processed with the contaminated saline. PCR ribotypes of the contaminant matched those of the clinical isolates. In vitro, P aeruginosa strains were viable in commercial nonbacteriostatic saline, but never caused visible turbidity. Six patients received antibiotics for their presumed infections; four patients had peripherally inserted central catheters placed, and one experienced severe anaphylactic reactions to several antibiotics. CONCLUSIONS: Pseudoepidemics due to common organisms are often difficult to detect, and delayed recognition can result in substantial morbidity. This outbreak investigation illustrates the potential for contamination of diluents in the microbiology laboratory and emphasizes the need for meticulous quality control.

Streptococcal toxic shock-like syndrome as an unusual complication of laparoscopic tubal ligation. A case report.

Toxic shock-like syndrome due to Streptococcus pyogenes is an unusual occurrence. Previously reported cases have been the result of focal infections with S pyogenes. We present a case in which manipulation of a colonized mucosal surface during laparoscopic tubal ligation was the presumed cause of the sepsis syndrome. Whereas other reports of this syndrome have all noted concurrent infections with S pyogenes, in this instance it was unclear if toxin-mediated disease was initiated by mild endometritis or iatrogenic manipulation of a colonized mucosal surface.

PIP: In Pennsylvania, a 29-year-old woman was admitted to Temple University Health Sciences Center in Philadelphia with hypotension (100/80 mmHg), fever (105.3 degrees Fahrenheit), and a diffuse, nondesquamating erythroderma. Five weeks earlier, she had delivered her last child vaginally. Three days before admission, she had undergone endotracheal intubation so surgeons could perform a laparoscopic tubal ligation with Falope Rings. Two days before the tubal ligation, she had had a sore throat. She experienced no surgical complications and was discharged the same day as the operation. The day before her latest admission, she experienced nausea, vomiting, diarrhea, fever, chills, and diffuse abdominal pain. Upon admission, her surgical incisions were clean and dry and had no erythema. Her pulse rate was 140 beats/minute. Her respiration rate was 20/minute. The white blood cell count was 15,200 cells/cu. m (71% neutrophils, 23% band forms, 2% lymphocytes, and 4% monocytes). Her potassium level was 3.2 mmol/l. The anion gap was 22. All blood and urine cultures were negative. She experienced mild uterine tenderness. Upon admission, physicians administered ticarcillin-clavulanate and vancomycin for suspected postoperative pelvic infection. After learning that cervical and pharyngeal cultures were positive for Streptococcus pyogenes, physicians changed to ampicillin, 1 g intravenously every 6 hours. On the 6th day, she was discharged and prescribed 500 mg oral amoxicillin every 8 hours for 2 weeks. Within 2 weeks, she felt fine, had a normal physical examination, no fever, and no rash. The major signs and symptoms indicated a toxin-mediated illness. Both mucosal surfaces colonized by S. pyogenes were manipulated during laparoscopy and manipulation may have caused minor tissue injury and hyperemia with subsequent dissemination of streptococcal toxin. In conclusion, the patient had a S. pyogenes toxin-induced toxic shock-like syndrome that mimicked a pelvic wound infection with gram-negative septicemia.

A comparison of serial plate agar dilution, Bauer-Kirby disk diffusion, and the Vitek AutoMicrobic system for the determination of susceptibilities of Klebsiella spp., Enterobacter spp., and Pseudomonas aeruginosa to ten antimicrobial agents.

The use of rapid, automated technologies for assessment of antimicrobial susceptibility and determination of minimum inhibitory concentrations has been evolving for over a decade. We compared the Vitek AutoMicrobic system and Bauer-Kirby disk diffusion with the National Committee for Clinical Laboratory Standards methods of serial plate agar dilution for qualitative and quantitative susceptibilities of 301 hospital isolates of Klebsiella spp., Enterobacter spp., and Pseudomonas aeruginosa. Antibiotics tested were aztreonam, cefoperazone, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, piperacillin, ticarcillin-clavulanic acid, and tobramycin. Agar dilution and Bauer-Kirby results were more strongly correlated for all three genera than were the results for agar dilution and Vitek. If agar dilution is presumed to be the "gold standard," Bauer-Kirby disk diffusion had only half the number of false susceptibles as did the Vitek. Thus, the Vitek AutoMicrobic system seems to be somewhat less reliable for both qualitative and quantitative measurement of susceptibility and resistance than is Bauer-Kirby disk diffusion.

A comparison of Streptococcus pyogenes (group A streptococcal) bacteremia at an urban and a suburban hospital. The importance of intravenous drug use.

BACKGROUND: There has been a recent resurgence of severe infections with Streptococcus pyogenes, including bacteremias and a toxic shock-like syndrome. The purpose of this study was to examine the influence of intravenous drug use on the incidence, clinical epidemiology, and severity of S pyogenes bacteremia. METHODS: We conducted a retrospective survey of medical records at a 500-bed tertiary care urban hospital and at a nearby 500-bed suburban university-affiliated hospital. All patients from each hospital with documented S pyogenes bacteremia from January 1, 1979, to December 31, 1989, were included. We examined demographic and clinical data from cases at the two institutions, serologic findings from a subset of isolates from the urban hospital, and factors associated with mortality from S pyogenes bacteremia by stepwise logistic regression analysis. RESULTS: Ninety-five cases of S pyogenes bacteremia were identified, with 65% (62 cases) occurring at the urban center. Intravenous drug use occurred more frequently at the urban center (P < .005); the injecting drug users were significantly younger than the non-drug-using population (P = .001). Infection with the human immunodeficiency virus occurred in a subset of the injecting drug users at the urban center. Cellulitis and cutaneous abscesses were the most common sources of bacteremia at both centers. During the study period, the numbers of S pyogenes bacteremias increased at the urban center (P = .007), accompanied by a significant increase in the proportion of infections associated with parenteral drug use (P = .003). There was no change in the prevalence of any T type throughout the study period and no clustering of T types among injecting drug users. The overall mortality was 23% (20/89). By logistic regression analysis, age older than 65 years (relative risk [RR], 14; 95% confidence interval [CI], 3.2 to 68) and the presence of the toxic shock-like syndrome (RR, 36; 95% CI, 2.2 to 600) were significantly associated with mortality due to S pyogenes bacteremia. CONCLUSIONS: Intravenous drug use accounted for an increase in cases of S pyogenes bacteremia at an inner-city hospital. However, advanced age and the toxic shock-like syndrome were the most important predictors of mortality.

Malaria during pregnancy: neonatal morbidity and mortality and the efficacy of chloroquine chemoprophylaxis.

In malaria-endemic regions, the impact of malaria upon pregnancy and the value of chemoprophylaxis for malaria for pregnant women remain controversial. We prospectively studied 302 pregnant women who presented in labor to Centre Médical Evangélique, Nyankunde, Zaire. We evaluated the incidence of malarial infection in mothers, placentas, and neonates and examined the effect of infection on birth weight and perinatal mortality. We analyzed the outcome of pregnancy in relation to prophylaxis with chloroquine, controlling for parity and prenatal clinic attendance. Peripartum smears of maternal blood (21%), placentas (33%), cord blood (9%), and neonatal blood (7%) were positive for Plasmodium falciparum. Maternal malaria increased the risk of perinatal death (relative risk [RR] = 12.4) and low birth weight (RR = 3.7). Neonatal malaria increased the risk of perinatal death (RR = 7.2). Chloroquine prophylaxis protected against maternal (RR = 0.4) and fetal malaria (RR = 0.2), low birth weight (RR = 0.39), and perinatal death (RR = 0.38). Peripartum malaria increases the risk of perinatal death and low birth weight. Chemoprophylaxis with chloroquine during pregnancy may have a protective effect, even in certain areas where chloroquine-resistant P. falciparum is endemic.

Development of new antibiotic resistance in methicillin-resistant but not methicillin-susceptible Staphylococcus aureus.

The frequency of infections caused by multidrug-resistant Staphylococcus aureus continues to increase while the numbers of alternative therapeutic agents remain limited. To investigate the changing patterns of in-vitro susceptibility of S. aureus to 16 antibiotics, 190 clinical isolates from two different years were studied. The MICs of methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains isolated in 1987 were compared with those of similar numbers of strains isolated in 1989. For MRSA > or = 90% of isolates from both years were resistant to clindamycin, gentamicin and erythromycin. These strains remained highly susceptible to vancomycin (100%), minocycline (90%) and rifampicin (100%). The greatest increase in resistance was observed for ofloxacin (2% in 1987 vs 62% in 1989); cross-resistance to all of the quinolones tested was demonstrated. MSSA strains remained susceptible to vancomycin (100%), minocycline (98%), rifampicin (100%), clindamycin (90%), gentamicin (90%) and ciprofloxacin (98%). It is concluded that methicillin susceptibility is a useful marker for selecting potential agents for the treatment of infections caused by S. aureus. A combination of minocycline and rifampicin may be a useful alternative to vancomycin for treating MRSA infections.

Infections complicating mycosis fungoides and Sézary syndrome.

OBJECTIVE: To determine, in patients with mycosis fungoides and Sézary syndrome, the incidence of infections, the importance of nosocomial infections, and the epidemiologic factors associated with cutaneous and visceral infections. DESIGN AND SETTING: Retrospective inception cohort study at a university medical center referral clinic. PATIENTS: Three hundred fifty-six patients with mycosis fungoides or Sézary syndrome. MAIN OUTCOME MEASURES: Incidence rates for specific infections, and multivariate risk ratios for demographic and clinical factors associated with infection. RESULTS: Cutaneous bacterial infection was most common (17.0 infections per 100 patient-years), followed by cutaneous herpes simplex virus and herpes zoster virus infection (3.8 infections per 100 patient-years), bacteremia (2.1 infections per 100 patient-years), bacterial pneumonia (1.7 infections per 100 patient-years), and urinary tract infection (1.4 infections per 100 patient-years). Twenty-seven percent of herpesvirus infections disseminated on the skin but none disseminated to internal organs. Pneumonia or bacteremia was present in 88% of patients who died of infection. Only three patients had invasive fungal or protozoal infection. Nosocomial infections accounted for 19% of cutaneous bacterial infections, 59% of bacteremias, 62% of pneumonias, and 88% of infections leading to death. By logistic and Cox regression, the presence of extracutaneous involvement with lymphoma was the most important independent risk factor for recurrent bacterial skin infection (risk ratio [RR], 12; 95% confidence interval [CI], 1.2 to 120), disseminated herpesvirus infection (RR, 28; 95% CI, 2.7 to 290), bloodstream infection (RR, 5.5; 95% CI, 1.7 to 18), and death from infection (RR, 15; 95% CI, 3.6 to 64). CONCLUSIONS: Community-acquired bacterial skin infections are a common cause of morbidity in patients with mycosis fungoides and Sézary syndrome but are usually treated without hospital admission. Bacteremia and pneumonia, which are usually nosocomial, are the major infectious causes of death. Advanced disease stage, independent of corticosteroids and other therapies, is the most important risk factor for both cutaneous and systemic infections.

Comparison of infections in Hickman and implanted port catheters in adult solid tumor patients.

Long-term therapy of oncology patients has been facilitated by permanent indwelling central venous catheters, but catheter-related infections remain a serious complication of their use. Using a retrospective matched cohort design, we compared the risk of catheter-related infection in 47 adult solid tumor patients with right atrial Hickman catheters and 94 patients with totally implanted port catheters. Patients were matched for primary solid tumor, presence of metastases, age, gender, and date of catheter insertion. Seven of 47 patients with Hickman catheters developed catheter-related infection (1.8 infections/1,000 catheter days at risk) compared with 10 of 94 patients with implanted port catheters (0.4/1000 catheter days, P less than 0.0002). Hickman catheters were used more often for terminally ill patients than were port catheters which was a potential source of bias, but results were unchanged after stratifying patients on lifespan. Our study suggests that there are fewer infections in port than in Hickman catheters in adult patients with solid tumors, but prospective randomized studies are needed.

Sporothrix schenckii fungemia without disseminated sporotrichosis.

Fungemia is a rare complication of Sporothrix schenckii infection and has always been associated with disseminated sporotrichosis. We describe an immunocompetent patient with localized lymphocutaneous sporotrichosis from whose blood the fungus was isolated. A lysis-centrifugation blood culture system may have improved our ability to detect low-level S. schenckii fungemia.

Infectious mononucleosis in older adults.

Infectious mononucleosis as a manifestation of primary Epstein-Barr virus infection occurs uncommonly in adults over age 40. While fever is almost universal, older patients with the disease often present without lymphadenopathy, pharyngitis, splenomegaly, lymphocytosis or atypical lymphocytes. Jaundice and hepatomegaly occur more commonly in older patients than in adolescents and create diagnostic confusion. Often, infectious mononucleosis in this age group is confused with lymphoma, leukemia or biliary obstruction, or is classified as "fever of unknown origin."

Risk factors for Clostridium difficile toxin-associated diarrhea.

The hospital-wide attack rate for Clostridium difficile-associated diarrhea at our tertiary-care university hospital was 0.02 per 100 patient discharges (0.02%) in 1982, but 0.41% and 1.47% in 1986 and 1987, respectively, with a peak incidence of 2.25% in the fourth quarter of 1987. Hospital antibiotic usage patterns showed concurrent increased use of third-generation cephalosporins, and intravenous vancomycin and metronidazole. Thirty-seven cases selected for study were older than 37 control patients, more likely to have an underlying malignancy and less likely hospitalized on the obstetrics/gynecology service. Their mean duration of hospitalization prior to diagnosis was 21 days, versus a mean total length of stay of eight days for controls. All cases received antibiotics, compared to 24 of the controls. Cases were given more antibiotics for longer periods, and more often received clindamycin, third-generation cephalosporins, aminoglycosides and vancomycin. Gender, race, duration of hospitalization, prior surgery and antiulcer therapy were not significant by logistic regression analysis. Epidemiologic variables with significantly different adjusted odds ratios (95% confidence intervals) were age greater than 65 years (14.1, 1.4-141), intensive care unit residence (39.2, 2.2-713), gastrointestinal procedure (23.2, 2.1-255) and more than ten antibiotic days (summation of days of each antibiotic administered) (16.1, 2.2-117). Control measures included encouraging earlier isolation and treatment of suspected cases and formulary restriction of clindamycin, with use of metronidazole for therapy of anaerobic infections. By the second half of 1988, the attack rate had dropped progressively to 0.74%.

Antipyretic orders in a university hospital.

PURPOSE: Antipyretics are prescribed for many hospitalized patients, but details concerning prescribing practices are not known. This study was designed to determine the incidence and format of antipyretic orders in a university-based tertiary-care center, and to ascertain whether orders are correlated with patient characteristics or hospital services. PATIENTS AND METHODS: The records of 300 randomly selected patients on the medicine, general surgery, neurosurgery, and obstetrics and gynecology services, and of 75 patients admitted with pneumonia and fever were retrospectively reviewed using a standardized data form. RESULTS: Orders for acetaminophen prn (as needed), without further explanation, were interpreted by the nursing staff as antipyretic orders; 78% of patients with such an order and fever received acetaminophen during the febrile episode. If orders of this type were included, 153 (51%) of the randomly selected patients received an antipyretic order. Gender, age, duration of hospitalization, intensive care unit residence, fever, and presence of a condition worsened by fever were not significant independent predictors of antipyretic prescription, but documented infection and hospitalization on the medicine and neurosurgery services were, with adjusted odds ratios of 2.5 (95% confidence interval [CI] 1.3 to 5.0), 9.4 (95% CI 3.6 to 25), and 14 (95% CI 5.0 to 41), respectively. Of patients who received an antipyretic order, 70% had an admission order for antipyretics; 26%, an order prompted by fever; and 79%, an order while afebrile. In 86%, the order was written prn without further explanation. Around-the-clock dosing, automatic stop orders, and acknowledgement and justification of orders were rare. CONCLUSION: Antipyretic orders are routine and correlate more strongly with hospital service than with individual patient characteristics. They are umprecisely written and generally leave decisions about antipyretic administration to the complete discretion of the nursing staff.

Risk factors for acquisition of gentamicin-resistant enterococci. A multivariate analysis.

High-level gentamicin resistance in enterococci is an increasing problem in hospitalized patients. Multiple risk factors for the acquisition of these organisms have been identified, but these risk factors are highly interrelated, and it has been unclear which of them are truly important. We performed a case-control study comparing 37 patients colonized or infected with resistant enterococci with 84 patients with susceptible strains. Crude odds ratios were significant for nosocomial acquisition, duration of hospitalization, hospitalization on the medical service or in an intensive care unit, number and duration of antibiotics received, and receipt of several individual antibiotics. By logistic regression, hospitalization longer than 2 weeks (odds ratio, 5.4; 95% confidence interval, 1.7 to 17) and receipt of five or more antibiotics (odds ratio, 26; 95% confidence interval, 2.8 to 250) were significantly associated with colonization or infection with resistant enterococci. Patients with these latter two risk factors may be targeted in infection control efforts.