Biomedical subjects
Publications and source records attributed to A W Karchmer.
The majority of cases of Staphylococcus aureus bacteremia are hospital-acquired, and most are associated with infected intravenous catheters. Preventive measures, early detection of infections, and strategies for effective treatment have become matters of increasing urgency.
PURPOSE: A prospective clinical and molecular epidemiologic study was conducted to define the frequency of nosocomial Clostridium difficile patient-to-patient transmission in an urban tertiary referral hospital. PATIENTS AND METHODS: Over a 6-month period, environmental cultures for C difficile were obtained from patients with new positive stool cytotoxin assay (index cases); stool samples were obtained from selected patient contacts (the roommate, occupants of adjacent rooms, and the patient occupying the index room after discharge of the index case); and hand cultures were obtained from personnel contacts. C difficile isolates were analyzed by pulse-field gel electrophoresis (PFGE) or, for isolates that were nontypeable by PFGE, by restriction enzyme analysis. RESULTS: During the study period, we identified 98 index cases of C difficile toxin-associated diarrhea, including focal outbreaks on two wards totaling 26 cases within a 2-month interval. Environmental contamination was detected at > or = 1 sites in 58% of rooms and often involved wide dispersed areas. Among 99 prospectively identified patient contacts, C difficile was cultured from the stool of 31 (31%), including 12 with diarrhea and 19 who were asymptomatic. C difficile was cultured from the hands of 10 (14%) of 73 personnel. Molecular analysis resolved 31 typing profiles among the index isolates; the most common profile (designated strain D1) was represented by 30 isolates. Among the isolates from patient contacts, 5 of 12 from symptomatic contacts matched the corresponding index isolate, and only 1 of 19 from asymptomatically colonized contacts matched. Transmission to personnel or patient contacts of the strain cultured from the corresponding index case was correlated strongly with the intensity of environmental contamination. Strain D1 was frequently represented among isolates associated with heavy environmental contamination, with personnel carriage, and with development of symptomatic illness among prospectively identified contacts. CONCLUSIONS: Intense environmental contamination and transmission to close personnel and patient contacts represented coordinated properties of an individual epidemic strain. For most epidemiologically linked contacts, positive cultures for C difficile did not result from transmission from the presumed index case.
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Osteomyelitis and soft-tissue foot infections continue to be the source of major amputations in the diabetic patient. Many of these amputations can be prevented with a prompt, aggressive, and integrated approach. Foot alterations should be appropriately investigated for osteomyelitis and culture-driven antimicrobial therapy combined with aggressive surgical intervention, including revascularization when necessary, should be pursued. This approach increases the chances for limb salvage. Early discharge from the hospital with HIVAT offers a safe and effective alternative to a prolonged hospital stay with significant cost savings in appropriately selected patients.
OBJECTIVE: To provide guidelines for the treatment of endocarditis in adults caused by the following microorganisms: viridans streptococci and other streptococci, enterococci, staphylococci, and fastidious gram-negative bacilli of the HACEK group. PARTICIPANTS: An ad hoc writing group appointed by the American Heart Association under the auspices of the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young. EVIDENCE: Published studies of the treatment of patients with endocarditis and the collective clinical experience of this group of experts. CONSENSUS PROCESS: The recommendations were formulated during meetings of the working group and were prepared by a writing committee after the group had agreed on the specific therapeutic regimens. The consensus statement was subsequently reviewed by standing committees of the American Heart Association and by a group of experts not affiliated with the working group. CONCLUSIONS: Sufficient evidence has been published that recommendations regarding treatment of the most common microbiological causes of endocarditis (viridans streptococci, enterococci, Streptococcus bovis, staphylococci, and the HACEK organisms) are justified. There are insufficient published data to make a strong statement regarding the efficacy of specific therapeutic regimens for cases of endocarditis due to microorganisms that uncommonly cause endocarditis. As a useful aid to the practicing clinician, the writing group developed a consensus opinion regarding management of endocarditis caused by the most commonly encountered microorganisms and regarding those cases due to infrequent causes of endocarditis.
OBJECTIVE: To determine factors that predict complications and examine outcomes of Staphylococcus aureus bacteremia according to the duration of antibiotic therapy. METHODS: Clinical data were extracted from charts of patients with positive blood cultures for S aureus at a single institution during a 2-year period. RESULTS: Of 102 patients with S aureus bacteremia, 55 were considered to have bacteremia attributable to an intravascular catheter, including five patients who were bacteremic after percutaneous transluminal coronary angioplasty. Among the other 50 patients with S aureus catheter-associated bacteremia, infection was community acquired in 18 and nosocomial in 32. Septic pulmonary emboli were more common in patients with community-acquired S aureus catheter-associated bacteremia, most of whom had Hickman catheters or venous access disks. Delayed removal of the infected catheter was associated with persistence of bacteremia (P = .01). With patients with early complications excluded, patients treated for 10 to 15 days had clinical characteristics similar to those of patients treated with longer courses of antibiotics and had similarly low rates of relapse (0% vs 4.7%). In contrast, treatment with parenteral antibiotics for less than 10 days appeared to be inadequate in that relapse occurred in two of three such patients. Staphylococcus aureus catheter-associated bacteremia associated with percutaneous transluminal coronary angioplasty was complicated by a femoral artery mycotic aneurysm in two of five patients. CONCLUSION: Approximately one third of S aureus catheter-related bacteremias were community acquired, reflecting increased usage of intravascular devices for home parenteral support. A 10- to 15-day course of parenteral antibiotics was equivalent to longer courses of therapy in patients without early complications.
A retrospective cohort study was conducted to determine the incidence of major infectious complications after orthotopic liver transplantation and to compare outcomes in patients receiving either cyclosporine (CsA) or FK506 (tacrolimus) as primary immunosuppression. Of 133 transplants performed in 118 patients, 124 transplant episodes were evaluated. Cytomegalovirus (CMV) infection (INF) and disease (DIS), deep fungal infection (DFI), and intraabdominal bacterial infections (IAI) were catalogued. The overall incidences of major infectious outcomes were: CMV INF = 33%; CMV DIS = 19%; DFI = 15%; and IAI = 25%. Cox proportional hazard analysis identified donor seropositivity, OKT3 as secondary immunosuppression and initial intensive care unit (ICU) duration as risk factors for CMV INF and DIS in the overall population. Fungal colonization was the dominant risk factor associated with deep fungal infection. A choledochojejunostomy anastomosis, the number of cellular blood products transfused at the time of transplantation surgery, and prior CMV INF were independent risk factors for both fungal colonization and deep infection. The single risk factor identified for intraabdominal bacterial infections was the number of cellular blood products transfused at the time of surgery. In the Cox proportional hazards model the relative risk (RR) for each category of infection was lower in the FK506 group (CMV: RR = .87, 95% confidence interval [C.I.] = [.32-2.4]; DFI: .58 [.13-2.6]; IAI: .51 [.15-1.7]), but the effect was not statistically significant. Survival was similar in patients receiving FK506 or CsA. CMV INF and DFI were independent predictors of death for all patients. Risk factors identified for CMV INF and DIS support the findings of others. Higher intraoperative blood product requirements and complicated intraoperative or postoperative courses increase the risk for IAI or DFI. The development of effective strategies to prevent CMV and fungal infections in liver transplant recipients remains a priority for future endeavors.
OBJECTIVE: To assess a bedside technique for diagnosing osteomyelitis. DESIGN: We prospectively assessed infected pedal ulcers for detectable bone by probing with a sterile, blunt, stainless steel probe. We then examined the relationship between detection of bone and the presence or absence of osteomyelitis that was defined histopathologically and/or clinically. SETTING: A tertiary care center. PATIENTS: Seventy-five hospitalized diabetic patients with a total of 76 infected foot ulcers were studied. RESULTS: Osteomyelitis was diagnosed in 50 instances (66%) and was excluded in 26 instances. Bone was detected by probing in 33 of 50 ulcers with contiguous osteomyelitis; in contrast, bone was probed in only four of 26 ulcers without contiguous osteomyelitis (P < .001). Bone detected on probing was visible in only three instances. Palpating bone on probing the pedal ulcer had a sensitivity of 66% for osteomyelitis, a specificity of 85%, a positive predictive value of 89%, and a negative predictive value of 56%. CONCLUSIONS: Palpation of bone in the depths of infected pedal ulcers in patients with diabetes is strongly correlated with the presence of underlying osteomyelitis. If bone is palpated on probing, specialized roentgenographic and radionuclide tests to diagnose osteomyelitis are unnecessary. Probing for bone should be included in the initial assessment of all diabetic patients with infected pedal ulcers.
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Staphylococcus aureus infections may occur with greater frequency among patients with diabetes mellitus. This article reviews the available literature as it pertains to diabetes and S. aureus in three categories: colonization/carriage, bacteremia with or without metastatic complications, and dialysis-related infections. The clinical entity of pyomyositis is also discussed.
Invasive fungal infections occur in 5% to 45% of solid organ transplant recipients, and are a major cause of morbidity and mortality in the immunocompromised population. The net depression of host defenses and environmental factors, such as preoperative exposures to endemic mycoses or nosocomial and specific surgery-associated exposures, affect the development of invasive infection. Most fungal infections in solid organ transplant recipients occur within the first 2 months after transplantation. The most common pathogens in the majority of solid organ transplant recipients are Candida spp, followed by Aspergillus sp. Diagnosis is best made by a high index of suspicion and aggressive acquisition of specimens for culture; serologic tests are useful for infections due to Cryptococcus neoformans and Histoplasma capsulatum. Amphotericin B is the drug of choice for life-threatening infections. The triazoles, fluconazole and itraconazole, may be effective alternatives for less serious infections due to susceptible organisms. Prophylactic and preemptive treatment strategies require further study.
BACKGROUND: Amphotericin B has long been the standard treatment for candidemia, but its use is complicated by its toxicity. More recently, fluconazole, a water-soluble triazole with activity against candida species and little toxicity, has become available. We conducted a multicenter randomized trial that compared amphotericin B with fluconazole as treatment for candidemia. METHODS: To be eligible, patients had to have a positive blood culture for candida species, a neutrophil count > or = 500 per cubic millimeter, and no major immunodeficiency. Patients were randomly assigned to receive either amphotericin B (0.5 to 0.6 mg per kilogram of body weight per day) or fluconazole (400 mg per day), each continued for at least 14 days after the last positive blood culture. Outcomes were assessed by a group of investigators blinded to treatment assignment. RESULTS: Of the 237 patients enrolled, 206 met all entry criteria. The most common diagnoses were renal failure, nonhematologic cancer, and gastrointestinal disease. There was no statistically significant difference in outcome: of the 103 patients treated with amphotericin B, 81 (79 percent) were judged to have been treated successfully, as were 72 of the 103 patients treated with fluconazole (70 percent P = 0.22; 95 percent confidence interval for the difference, -5 to 23 percent). The bloodstream infection failed to clear in 12 patients in the amphotericin group and 15 in the fluconazole group; the species most commonly associated with failure was Candida albicans. There were 41 deaths in the amphotericin group and 34 deaths in the fluconazole group (P = 0.20). Intravascular catheters appeared to be the most frequent source of candidemia. There was less toxicity with fluconazole than with amphotericin B. CONCLUSIONS: In patients without neutropenia and without major immunodeficiency, fluconazole and amphotericin B are not significantly different in their effectiveness in treating candidemia.
Limb- or life-threatening complications in patients with diabetes can be prevented with an integrated, multidisciplinary approach. Most patients seen in clinical practice are in the early stages of the disease process. Glycemic control retards the progression of neuropathy, which is the most important risk factor for ulceration. Early detection of the loss of protective sensation and implementation of strategies to prevent ulceration will reduce the rates of limb-threatening complications. Clinicians should routinely examine the feet of diabetic patients. Education in foot care, proper footwear, and close follow-up are required to prevent or promptly detect neuropathic injury. If ulceration occurs, removal of pressure from the site of the ulcer and careful management of the wound will allow healing in most cases. The failure to heal despite these measures should prompt a search for associated arterial insufficiency. If infection is present, appropriate antimicrobial therapy combined with immediate surgical intervention, including revascularization when necessary, will increase the chances of saving the limb. With this comprehensive approach, it is possible to achieve the goal of a 40 percent decrease in amputation rates among diabetic patients by the year 2000.
Clostridium difficile is the major identifiable infectious cause of nosocomial diarrhea. A prospective study was conducted at New England Deaconess Hospital (Boston) to examine risk factors for C. difficile carriage at both admission and follow-up. Specimens from patients admitted to two wards (one medical, one surgical) and three intensive care units (two surgical, one medical) were cultured weekly until discharge. For 89 (18%) of 496 patient admissions, at least one culture was positive. The prevalence of culture positivity within 72 hours of admission was 11%. Risk factors for culture positivity at admission were prior C. difficile diarrhea (adjusted odds ratio [OR] = 9.5), renal insufficiency (OR = 6.7), and recent hospitalization elsewhere (OR = 3.1). Fifteen percent of patients for whom initial cultures were negative and for whom follow-up cultures were performed acquired C. difficile. Admission to the vascular surgery service (relative risk [RR] = 2.3) and liver transplantation (RR = 4.2) were significant risk factors for C. difficile acquisition. Patients asymptomatically colonized on admission had very low risk (1 in 44) for subsequent development of C. difficile diarrhea. In contrast, nine (47%) of 19 patients who acquired toxigenic strains developed C. difficile diarrhea, a finding suggesting that progression to diarrhea occurs early after acquisition or does not occur at all. The relatively high prevalence of culture positivity at admission may be characteristic of tertiary care hospitals and adds to the difficulty of controlling this nosocomial pathogen.
In a double-blind randomized trial, imipenem/cilastatin (I/C; 500 mg every 6 hours) and ampicillin/sulbactam (A/S; 3 g every 6 hours) were compared in regard to their efficacy for initial empirical and definitive parenteral treatment of limb-threatening pedal infection in diabetic patients. The major endpoints of treatment were cure (resolution of soft-tissue infection), failure (inadequate improvement, necessitating a change in antibiotic therapy), and eradication (clearance of all pathogens from the wound and any bone cultures). Patients in the two treatment groups were similar in regard to the severity of diabetes; presence of neuropathy and peripheral vascular disease; site and severity of infection; pathogen isolated; and frequency of osteomyelitis (associated with 68% of the 48 A/S-treated infections and 56% of the 48 I/C-treated infections). After 5 days of empirical treatment, improvement was noted in 94% of the A/S and 98% of the I/C recipients. At the end of definitive treatment (days' duration [mean +/- SD]: 13 +/- 6.5 [A/S], 14.8 +/- 8.6 [I/C]), outcomes were similar: cure, 81% (A/S) vs. 85% (I/C); failure, 17% (A/S) vs. 13% (I/C); and eradication, 67% (A/S) vs. 75% (I/C). Treatment failures were associated with the presence of antibiotic-resistant pathogens and possible nosocomial acquisition of infections. The number of adverse events among patients in the two treatment groups was similar: 7 in the A/S group (4 had diarrhea and 3 had rash) and 9 in the I/C group (5 had diarrhea, 2 had severe nausea, 1 had rash, and 1 had seizure). Efficacy of A/S and I/C is similar for initial empirical and definitive treatment of limb-threatening pedal infection in patients with diabetes.
Nosocomial Clostridium difficile infection was investigated at a hospital with 15 cases of C. difficile diarrhea per 1000 discharges. From January 1991 to May 1991, patients admitted or transferred to five wards or units had weekly rectal swabs taken for culture; in addition, all cytotoxin-positive stools were cultured. Restriction enzyme analysis (REA) was used for molecular typing. Among 205 isolates from 39 patients with C. difficile diarrhea and 67 asymptomatically colonized, 55 distinct REA banding patterns were identified. Evidence for patient-to-patient transmission was limited, in that numerous strains were found even among clustered cases of diarrhea. Patients who acquired C. difficile in the community or other hospitals constituted 32% of culture-positive patients and contributed 44% of the REA types. Diversity of C. difficile strains was in part the result of patients acquiring C. difficile in the community or other hospitals. High incidences of nosocomial C. difficile diarrhea do not necessarily indicate clonal epidemics.
A combined clinical and molecular epidemiologic analysis of 46 strains of Clostridium difficile, including 16 nosocomial isolates from one ward (outbreak ward) plus 17 other nosocomial isolates and 13 community-acquired isolates, was performed. HindIII digests of total cellular DNA were analyzed by restriction enzyme analysis (REA) and ribotyping; SmaI digests were analyzed by pulsed-field gel electrophoresis (PFGE). Isolates were assigned to typing groups on the basis of the profiles detected; isolates with closely related profiles were assigned to subgroups. The 16 isolates from the outbreak ward were resolved by both REA and PFGE into five distinct groups; 13 isolates represented two REA groups and three PFGE groups and two isolates were resolved as distinct groups by both techniques. DNA obtained from one isolate was persistently partially degraded, precluding analysis by PFGE. Seventeen sporadic nosocomial isolates were resolved by REA and PFGE into comparable numbers of groups (i.e., nine groups) and subgroups (i.e., 15 and 14 subgroups, respectively), with two isolates not evaluable by PFGE. The 13 epidemiologically unrelated community-acquired isolates were assigned to 11 groups by REA and to 12 groups by PFGE. Overall, ribotyping identified only nine groups among the 46 isolates. We conclude that REA and PFGE have comparable discriminatory powers for epidemiologic typing of C. difficile isolates and that ribotyping is appreciably less discriminatory. For a few isolates, partial DNA degradation prevented analysis by PFGE but not by REA or ribotyping; the cause of the degradation is unknown.
Long-term management of patients with Kawasaki disease should be tailored to the degree of coronary arterial involvement. This committee has made recommendations for each risk level about antiplatelet and anticoagulant therapy, physical activity, follow-up assessment by a pediatric cardiologist or primary care physician, and the appropriate diagnostic procedures that may be performed to evaluate cardiac disease. The risk level for a given patient with coronary arterial involvement may change over time because of changes in coronary artery morphology. The recommendations for management presented here are intended as practical interim guidelines until additional prospective or retrospective data are compiled to define more clearly the natural history of Kawasaki disease.