Rodney L. Thompson

Antibiotic prophylaxis for percutaneous endoscopic gastrostomy. A prospective, randomized, double-blind clinical trial.

Study Objective. To determine if prophylactic use of cefazolin reduces peristomal wound infection associated with percutaneous endoscopic gastrostomy. Design. Prospective, randomized, double-blind, placebo-controlled clinical trial. Setting. Academic medical center, referral-based, gastroenterology service. Patients. One hundred thirty hospitalized patients, 23 of whom were excluded. Of the remaining 107 patients, 52 (group I) were already using antibiotics at the time of randomization for gastrostomy, whereas 55 (group II) were not. Interventions. Patients received either intravenous saline as a placebo or intravenous cefazolin (1 g) 30 minutes before gastrostomy. Measurements and Main Results. For 1 week after gastrostomy, the peristomal area was evaluated and a score assigned each day for erythema (0 to 4), induration (0 to 3), and exudate (0 to 4). A maximum combined score of 8 or more or the development of pus was a criterion for infection. None of the patients in group I developed a wound infection. Only 2 of 27 group II patients given prophylaxis developed a wound infection, compared with 9 of 28 patients not given prophylaxis, a difference of 25% (95% confidence interval, 4.8 to 44.6%; p less than 0.025). The number of patients who developed a wound infection was 0 of 52 in group I and 2 of 27 in group II patients who received cefazolin, a difference of 7.4% (95% confidence interval, -2.5 to 17.3%; p = 0.07). Conclusion. Cefazolin prophylaxis significantly reduces the risk for peristomal wound infection associated with percutaneous endoscopic gastrostomy. It is needed, however, only for patients not already receiving antibiotic treatment at the time of gastrostomy.

Prevention of Infection in Critically Ill Patients by Selective Decontamination of the Digestive Tract

OBJECTIVE To determine whether selective decontamination of the digestive tract using oral and nonabsorbable antimicrobial agents and parenteral cefotaxime prevents infection in critically ill patients. DESIGN Randomized, controlled trial without blinding. SETTING Surgical trauma and medical intensive care units in a tertiary referral hospital. PATIENTS One hundred fifty patients admitted to surgical trauma and medical intensive care units during a 3-year interval, whose condition suggested a prolonged stay (greater than 3 days). INTERVENTION Patients were randomly allocated to an experimental group (n = 75) that received cefotaxime, 1 g intravenously every 8 hours for the first 3 days only, and oral, nonabsorbable antibiotics (gentamicin, polymyxin, and nystatin by oral paste and oral liquid) for the entire stay in the intensive care unit. Control patients (n = 75) received usual care. MEASUREMENTS The number of infections, total hospital days, and deaths, as well as the number of days in intensive care unit, were recorded. RESULTS Control patients experienced more infections (36 compared with 12, P = 0.04), including bacteremias (14 compared with 4, P = 0.05) and pulmonary infections (14 compared with 4, P = 0.03). Although total hospital days, days in intensive care, and the overall death rate all were lower in the treatment group, these differences were not statistically significant. Clinically important complications of selective decontamination of the digestive tract were not encountered. CONCLUSIONS Selective decontamination of the digestive tract decreases subsequent infection rates, especially by gram-negative bacilli, in selected patients during long-term stays in the intensive care unit.

Duration of Influenza A Virus Shedding in Hospitalized Patients and Implications for Infection Control

OBJECTIVE To assess the duration of shedding of influenza A virus detected by polymerase chain reaction (PCR) and cell culture among patients hospitalized with influenza A virus infection. SETTING Mayo Clinic (Rochester, Minnesota) hospitals that cater to both the community and referral populations. METHODS Patients 18 years old and older who were hospitalized between December 1, 2004, and March 15, 2005, with a laboratory-confirmed (ie, PCR-based) diagnosis of influenza A virus infection were consecutively enrolled. Additional throat swab specimens were collected at 2, 3, 5, and 7 days after the initial specimen (if the patient was still hospitalized). All specimens were tested by PCR and culture (both conventional tube culture and shell vial assay). Information on demographic characteristics, date of symptom onset, comorbidities, immunosuppression, influenza vaccination status, and receipt of antiviral treatment was obtained by interview and medical record review. Patients were excluded if informed consent could not be obtained or if the date of symptom onset could not be ascertained. RESULTS Of 149 patients hospitalized with influenza A virus infection, 50 patients were enrolled in the study. Most patients were older (median age, 76 years), and almost all (96%) had underlying chronic medical conditions. Of 41 patients included in the final analysis, influenza A virus was detected in 22 (54%) by PCR and in 12 (29%) by culture methods at or beyond 7 days after symptom onset. All 12 patients identified by culture also had PCR results positive for influenza A virus. CONCLUSION Hospitalized patients with influenza A virus infection can shed detectable virus beyond the 5- to 7-day period traditionally considered the duration of infectivity. Additional research is needed to assess whether prolonging the duration of patient isolation is warranted to prevent nosocomial outbreaks during the influenza season.

The Mayo prosthetic joint infection risk score: implication for surgical site infection reporting and risk stratification.

OBJECTIVE The goal of this study was to develop a prognostic scoring system for the development of prosthetic joint infection (PJI) that could risk-stratify patients undergoing total hip (THA) or total knee (TKA) arthroplasties. DESIGN Previously reported case-control study. SETTING Tertiary referral care setting from 2001 through 2006. METHODS A derivation data set of 339 cases and 339 controls was used to develop 2 scores. A baseline score and a 1-month-postsurgery risk score were computed as a function of the relative contributions of risk factors for each model. Points were assigned for the presence of each factor and then summed to get a subjects risk score. RESULTS The following risk factors were detected from multivariable modeling and incorporated into the baseline Mayo PJI risk score: body mass index, prior other operation on the index joint, prior arthroplasty, immunosuppression, ASA score, and procedure duration (c index, 0.722). The 1-month-postsurgery risk score contained the same variables in addition to postoperative wound drainage (c index, 0.716). CONCLUSION The baseline score might help with risk stratification in relation to public reporting and reimbursement as well as targeted prevention strategies in patients undergoing THA or TKA. The application of the 1-month-postsurgery PJI risk score to patients undergoing THA or TKA might benefit those undergoing workup for PJI.

Comparison of the Roche LightCycler vanA/vanB Detection Assay and Culture for Detection of Vancomycin-Resistant Enterococci from Perianal Swabs

ABSTRACT We compared the performance characteristics of a real-time PCR method, the LightCycler vanA/vanB detection assay (Roche Diagnostics Corporation, Indianapolis, Ind.) to that of Enterococcosel agar (BBL, Sparks, Md.) for direct detection of vancomycin-resistant enterococci (VRE) from 894 perianal stool swabs. For 421 of 894 swabs, the result for LightCycler PCR was compared to an Enterococcosel plate containing vancomycin at 6 μg/ml; for the remaining 473 swabs, the result for LightCycler PCR was compared to an Enterococcosel plate containing 8 μg/ml vancomycin. The LightCycler method produced considerably more positive results than either the Enterococcosel plate containing vancomycin at 6 μg/ml (n = 25 versus n = 11; sensitivity, 100%; specificity, 97%; positive predictive value [PPV], 42%; negative predictive value [NPV], 100%) or the Enterococcosel plate containing vancomycin at 8 μg/ml (n = 31 versus n = 10; sensitivity, 100%; specificity, 95%; PPV, 32%; NPV, 100%). When possible, additional testing, including culture, LightCycler PCR, and/or a conventional PCR method (PCR-restriction fragment length polymorphism assay), were performed on either the original specimens or original cultures or subsequent specimens for cases in which the original specimen was positive by LightCycler PCR but the Enterococcosel plate was negative. This additional testing demonstrated positive results for 7 of 14 (50%) evaluable discordant specimens which initially tested as LightCycler PCR positive but culture negative using the Enterococcosel plate containing vancomycin at 6 μg/ml and 12 of 17 (71%) evaluable discordant specimens which initially tested as LightCycler positive but culture negative using the Enterococcosel plate containing vancomycin at (8 μg/ml). These results demonstrate that the LightCycler VRE detection assay is considerably more sensitive than the standard culture method for detecting VRE directly from perianal swab specimens. The LightCycler assay also provides results much faster than culture (∼3.5 versus ≥72 h). The use of this test could have important implications for the effective control and prevention of nosocomial outbreaks of VRE.

Molecular, Serological, and Clinical Features of 16 Consecutive Cases of Invasive Streptococcal Disease

We performed a comprehensive analysis of the molecular, serological, and clinical features of 16 consecutive cases of invasive streptococcal disease (ISD). The majority of cases were linked to two group A streptococcus (GAS) clones closely related by pulsed-field gel electrophoresis (PFGE) and designated as PFGE-1 and PFGE-1.1. These clones, serotyped as M-3, T-3/B3264, carried an allelic variant of the gene that encodes pyrogenic exotoxin A (speA3) and the gene that encodes streptococcal superantigen (SSA) but different emm alleles that encode M-protein. The characteristics and clinical features of patients were similar to those described in previous reports, regardless of the responsible GAS clone. However, worse clinical outcomes (shock and death) were more frequent when patients infected with PFGE1/1.1 clones were considered as a group and compared with all other patients as a group. One striking feature in some patients with deep tissue infection was a lack of inflammatory cells despite the presence of numerous streptococci. An evaluation of PFGE profiles of GAS isolated elsewhere demonstrated that the PFGE-1 clone has caused invasive disease in other locations in the United States and in Japan.

Effects of 4 Hand-Drying Methods for Removing Bacteria From Washed Hands: A Randomized Trial

OBJECTIVE To evaluate the effects of 4 different drying methods to remove bacteria from washed hands. SUBJECTS AND METHODS One hundred adult volunteers participated in this randomized prospective study. All bacterial counts were determined using a modified glove-juice sampling procedure. The difference was determined between the amounts of bacteria on hands artificially contaminated with the bacterium Micrococcus luteus before washing with a nonantibacterial soap and after drying by 4 different methods (cloth towels accessed by a rotary dispenser, paper towels from a stack on the hand-washing sink, warm forced air from a mechanical hand-activated dryer, and spontaneous room air evaporation). The results were analyzed using a nonparametric analysis (the Friedman test). By this method, changes in bacterial colony-forming unit values for each drying method were ranked for each subject. RESULTS The results for 99 subjects were evaluable. No statistically significant differences were noted in the numbers of colony-forming units for each drying method (P = .72). CONCLUSION These data demonstrate no statistically significant differences in the efficiency of 4 different hand-drying methods for removing bacteria from washed hands.

Infectious rates of central venous pressure catheters: comparison between newly placed catheters and those that have been changed.

OBJECTIVE To analyze the rate of infection of de novo, guidewire exchanged, and new site replacement catheters in a cohort of patients in whom catheters were changed on the basis of the clinical discretion of the attending physicians. DESIGN We conducted an observational cohort study in catheterized patients in the intensive-care unit (ICU). MATERIAL AND METHODS ICU patients admitted between Jan. 1, 1991, and Dec.31, 1992, were eligible for enrollment in the study. Catheter care, replacement, and duration were prospectively documented. Catheter-related infection was prospectively evaluated. Rates of catheter-related infection were determined for de novo, guidewire exchanged, and new site replacement catheters and analyzed relative to the duration of placement of individual catheters and the total duration of central venous catheterization for a specific patient. RESULTS Fifty catheter-related infections developed in 2,470 patients. When the rate of catheter-associated infection was determined for each type of catheterization, de novo catheters had a lower observed rate of infection than either replacement type (P < or = 0.0001). After controlling for the effect of time, we found that the rate of catheter-related infections associated with a de novo catheter was less than the rate in guidewire exchanged catheters (P = 0.035). Rates of infection were similar between guidewire exchanged catheters and catheters replaced to a new site. CONCLUSION In a population of ICU patients in whom catheter change was governed by clinical judgement, no differences were noted between the observed rates of infection of new site replacement catheters and guidewire exchange catheters.

Surgical management of abdominal tuberculosis

Recent reports suggest an increased incidence of abdominal tuberculosis in the United States, particularly in high-risk groups. The aim of this study was to review the spectrum of abdominal tuberculosis and its surgical management at a tertiary referral center in the United States. The medical records of patients treated for abdominal tuberculosis at our institution between January 1992 and June 2001 were retrospectively reviewed. Eighteen patients were diagnosed with abdominal tuberculosis by microbiologic and/or histologic examination. The 10 men and eight women had a mean duration of symptoms of 4 months (range 1 to 24 months). Five were born in the United States, and 13 were foreign born (7 Asians and 6 Africans). The United States-born patients with abdominal tuberculosis, as compared to the foreign-born patients, were older (mean age 74 years vs.35 years), more likely to have chronic medical illnesses (80% vs.7%), and had concomitant pulmonary tuberculosis (60% vs. 0%). Computed tomography was the most frequent imaging modality (88%); findings suggestive of abdominal tuberculosis were mesenteric/omental stranding (50%), ascites (37%), and retroperitoneal lymphadenopathy (31%). Seventeen of the 18 patients required operative intervention, and one patient underwent CT-guided drainage of a psoas abscess. Laparoscopy was useful for diagnosis in eight patients; laparotomy was performed for complications of abdominal tuberculosis in six patients and to obtain a tissue diagnosis in three patients. Abdominal tuberculosis continues to represent a diagnostic challenge to clinicians. Among native-born white Americans, abdominal tuberculosis is primarily a disseminated disease of elderly, debilitated patients with chronic illnesses. Among foreign-born individuals, abdominal tuberculosis occurs in young, immunocompetent patients from endemic areas. Characteristic CT findings should be evaluated for abdominal tuberculosis in the appropriate clinical setting. Laparoscopy is an effective modality for diagnosis of peritoneal tuberculosis.

Should National Standards for Reporting Surgical Site Infections Distinguish between Primary and Revision Orthopedic Surgeries

OBJECTIVE To compare the surgical site infection (SSI) rate after primary total hip arthroplasty with the SSI rate after revision total hip arthroplasty. DESIGN Retrospective cohort study. SETTING Mayo Clinic in Rochester, Minnesota, a referral orthopedic center. PATIENTS All patients undergoing primary total hip arthroplasty or revision total hip arthroplasty during the period from January 1, 2002, through December 31, 2006. METHODS We obtained data on total hip arthroplasties from a prospectively maintained institutional surgical database. We reviewed data on SSIs collected prospectively as part of routine infection control surveillance, using the criteria of the Centers for Disease Control and Prevention for the definition of an SSI. We used logistic regression analyses to evaluate differences between the SSI rate after primary total hip arthroplasty and the SSI rate after revision total hip arthroplasty. RESULTS A total of 5,696 total hip arthroplasties (with type 1 wound classification) were analyzed, of which 1,381 (24%) were revisions. A total of 61 SSIs occurred, resulting in an overall SSI rate of 1.1% for all total hip arthroplasties. When stratified by the National Nosocomial Infection Surveillance (NNIS) risk index, SSI rates were 0.5%, 1.2%, and 1.6% in risk categories 0, 1, and 2, respectively. After controlling for the NNIS risk index, the risk of SSI after revision total hip arthroplasty was twice as high as that after primary total hip arthroplasty (odds ratio, 2.2 [95% confidence interval, 1.3-3.7]). In the analysis restricted to the development of deep incisional or organ space infections, the risk of SSI after revision total hip arthroplasty was nearly 4 times that after primary total hip arthroplasty (odds ratio, 3.9 [95% confidence interval, 2.0-7.6]). CONCLUSION Including revision surgeries in the calculation of SSI rates can result in higher infection rates for institutions that perform a larger number of revisions. Taking NNIS risk indices into account does not eliminate this effect. Differences between primary and revision surgeries should be considered in national standards for the reporting of SSIs.