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Biomedical subjects

A D Harris

Publications and source records attributed to A D Harris.

At least 19 recordsLinked to original sources
PubMed2004

Risk factors for postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus.

Risk factors for developing postoperative mediastinitis (POM) due to methicillin-resistant Staphylococcus aureus (MRSA) were analyzed in a case-case control study of patients who underwent median sternotomy during the period from 1994 through 2000. Three patient groups were studied. The first consisted of 64 patients with POM due to MRSA; the second consisted of 79 patients with POM due to methicillin-susceptible S. aureus (MSSA); and the third consisted of 80 uninfected control patients. In multivariable analysis, patients who were diabetic (adjusted OR, 2.86; 95% CI, 1.22-6.70), female (OR, 2.70; 95% CI, 1.25-5.88), and >70 years old (OR, 3.43; 95% CI, 1.53-7.71) were more likely to develop POM due to MRSA. In contrast, the only independent risk factor associated with POM due to MSSA was obesity (OR, 2.49; 95% CI, 1.25-4.96). Antimicrobial prophylaxis consisted primarily of cephalosporin antibiotics (administered to 97% of the patients). Changes in perioperative antimicrobial prophylaxis, in addition to other interventions, should be considered for prevention of POM due to MRSA in targeted, high-risk populations.

Age Factors↗
PubMed2004

Animal growth promoters: to ban or not to ban? A risk assessment approach.

The use of antibiotics for animal growth promotion has been controversial because of the potential transfer of antibiotic resistance from animals to humans. Such transfer could have severe public health implications in that treatment failures could result. We have followed a risk assessment approach to evaluate policy options for the streptogramin-class of antibiotics: virginiamycin, an animal growth promoter, and quinupristin/dalfopristin, a antibiotic used in humans. Under the assumption that resistance transfer is possible, models project a wide range of outcomes depending mainly on the basic reproductive number (R(0)) that determines the potential for person-to-person transmission. Counter-intuitively, the benefits of a ban on virginiamycin were highest for intermediate values of R(0), and lower for extremely high or low values of R(0).

Animal Husbandry↗
PubMed2003

Assessing risks for a pre-emergent pathogen: virginiamycin use and the emergence of streptogramin resistance in Enterococcus faecium.

Vancomycin-resistant enterococci (VRE) are an important cause of hospital-acquired infections and an emerging infectious disease. VRE infections were resistant to standard antibiotics until quinupristin/dalfopristin (QD), a streptogramin antibiotic, was approved in 1999 for the treatment of vancomycin-resistant Enterococcus faecium infections in people. After that decision, the practice of using virginiamycin in agriculture for animal growth promotion came under intense scrutiny. Virginiamycin, another streptogramin, threatens the efficacy of QD in medicine because streptogramin resistance in enterococci associated with food animals may be transferred to E faecium in hospitalised patients. Policy makers face an unavoidable conundrum when assessing risks for pre-emergent pathogens; good policies that prevent or delay adverse outcomes may leave little evidence that they had an effect. To provide a sound basis for policy, we have reviewed the epidemiology of E faecium and streptogramin resistance and present qualitative results from mathematical models. These models are based on simple assumptions consistent with evidence, and they establish reasonable expectations about the population-genetic and population-dynamic processes underlying the emergence of streptogramin-resistant E faecium (SREF). Using the model, we have identified critical aspects of SREF emergence. We conclude that the emergence of SREF is likely to be the result of an interaction between QD use in medicine and the long-term use of virginiamycin for animal growth promotion. Virginiamycin use has created a credible threat to the efficacy of QD by increasing the mobility and frequency of high-level resistance genes. The potential effects are greatest for intermediate rates of human-to-human transmission (R0 approximately equal 1).

Anti-Bacterial Agents↗
PubMed2001

Parallel analysis of individual and aggregated data on antibiotic exposure and resistance in gram-negative bacilli.

To evaluate the potential bias of analyzing aggregated data, we separately examined antibiotic exposure and resistance data for 35,423 patients admitted to a university hospital in Utah, from both an individual-patient perspective and group-level perspective. From 1994 through 1998, use of defined daily doses (per 1000 patient-days) of fluoroquinolones, third-generation cephalosporins, ampicillin-sulbactam, and imipenem increased by 82%, 38%, and 99%, and decreased by 38%, respectively, whereas group-level resistance rates of Enterobacteriaceae or Pseudomonas species changed only minimally. However, in individual-patient-level analyses performed by multivariable proportional hazards regression, exposure to a fluoroquinolone, third-generation cephalosporin, ampicillin-sulbactam, or imipenem was a strong risk factor for resistance to fluoroquinolones (adjusted hazard ratio [AHR], 4.0; P<.001), third-generation cephalosporins (AHR, 3.5; P<.001), ampicillin-sulbactam (AHR, 2.3; P=.008), or imipenem (AHR, 5.7; P<.001), respectively. Thus, group-level and individual-patient-level analyses of antibiotic-use-versus-susceptibility relations yielded divergent results. Multicenter studies should include individual-patient-level data to elucidate more fully the relation between antibiotic exposure and resistance.

Ampicillin↗
PubMed2001

Methodological principles of case-control studies that analyzed risk factors for antibiotic resistance: a systematic review.

Case-control studies that analyze the risk factors for antibiotic-resistant organisms have varied epidemiological methodologies, which may lead to biased estimates of antibiotic risk factors. A systematic review of case-control studies that analyzed risk factors for antibiotic-resistant organisms addressed 3 methodological principles: method of control group selection, adjustment for time at risk, and adjustment for comorbid illness. A total of 406 abstracts were reviewed. Thirty-seven studies met the inclusion and exclusion criteria and were reviewed and evaluated for the 3 methodological principles. Thirteen (35%) of 37 studies chose the preferred control group. Eleven adjusted for time at risk. Twenty-seven adjusted for comorbid illness. Future studies need to consider more closely the optimization of control group selection, adjusting for confounding caused by time at risk, and adjusting for confounding caused by comorbid illness.

Case-Control Studies↗
PubMed2001

National and regional assessment of the antibacterial soap market: a step toward determining the impact of prevalent antibacterial soaps.

BACKGROUND: Consumer antibacterial soaps contain triclosan or triclocarban. No scientific data have been published to suggest that the use of antibacterial agents in household products prevents infection, and triclosan resistance mechanisms have recently been identified. Little data are available regarding the prevalence of antibacterial agents contained in consumer soaps. METHODS: In a physician-performed survey of 23 stores in 10 states from December 1999 to April 2000, investigators determined the number of national brand liquid and bar soaps and percent of each containing antibacterial agents sold at national chain, regional grocery, and Internet stores. RESULTS: Antibacterial agents were present in 76% of liquid soaps and 29% of bar soaps available nationally. There were no differences found between national, regional, and Internet stores. CONCLUSION: Overall, 45% of surveyed soaps contain antibacterial agents. With limited documented benefits and experimental laboratory evidence suggesting possible adverse effects on the emergence of antimicrobial resistance, consumer antibacterial use of this magnitude should be questioned.

Anti-Infective Agents↗
PubMed2000

Benefits of negative penicillin skin test results persist during subsequent hospital admissions.

For an initial series of 38 patients with negative skin test results, we reviewed retrospectively all subsequent admissions over a 2-year period. For 38 patients with negative initial skin test results, there were 48 subsequent readmissions to our institution, of which 35 required antibiotics. beta-lactams were prescribed for 86% of admissions; a penicillin for 37%, and a cephalosporin for 51%. All infections were cured, and there were no allergic drug reactions during any of the admissions that were reviewed.

Anti-Bacterial Agents↗
PubMed2000

A survey on handwashing practices and opinions of healthcare workers.

Studies have consistently demonstrated rates of handwashing compliance are less than 50%. The objective of this study was to gain the following information about handwashing: self-reported compliance; attitudes towards handwashing in different patient settings; and attitudes towards interventions aimed at increasing compliance. A 74-question survey was administered to healthcare workers in two tertiary care hospitals. One hundred and ninety nine healthcare workers completed the survey and 89% reported that handwashing is an important means of preventing infection. Sixty-four percent believed that they washed their hands as often as their peers and 2% believed that they washed less often than their peers. Patients with diarrhoea, AIDS or patients on antibiotics led to increased handwashing. Relative to potential interventions, 76% reported that rewards for handwashing would have no effect, 73% reported that punishment would have no effect and 80% reported that easy access to sinks and availability of washing facilities would lead to increased compliance. This survey suggests that healthcare workers understand the importance of handwashing, but tend to overestimate their own compliance. Healthcare workers are not in favour of interventions involving rewards and punishments, but are more attracted to interventions that make handwashing easier.

Attitude of Health Personnel↗
PubMed2000

Risk factors for recovery of ampicillin-sulbactam-resistant Escherichia coli in hospitalized patients.

Ampicillin-sulbactam resistance in Escherichia coli is an emerging problem. This study determined risk factors for the recovery of ampicillin-sulbactam-resistant E. coli in hospitalized patients. A case-control design was used to compare two groups of case patients with control patients. The first group of case patients consisted of patients from whom nosocomially acquired ampicillin-sulbactam-resistant E. coli strains were isolated, and the second group of case patients consisted of patients from whom ampicillin-sulbactam-susceptible E. coli strains were isolated. Control patients were a random selection among 5% of all patients admitted during the same time period. Risk factors analyzed included antimicrobial drug exposure, comorbid conditions, and demographics. Univariate and multivariate analyses were performed. Ampicillin-sulbactam-resistant E. coli strains were isolated from 175 patients, and ampicillin-sulbactam-susceptible E. coli strains were isolated from 577 patients. Nine hundred thirty-four control patients were selected. Exposure to penicillin antibiotics as a class and to ampicillin and ampicillin-sulbactam individually were the only significant, independent risk factors associated with the isolation of ampicillin-sulbactam-resistant E. coli (odds ratio [OR] = 2.32 [P < 0.001], OR = 3.04 [P = 0.02], and OR = 1.72 [P = 0.04], respectively), but they were not associated with the isolation of ampicillin-sulbactam-susceptible E. coli. Interestingly, exposure to piperacillin-tazobactam tended to protect against the isolation of E. coli strains resistant to ampicillin-sulbactam, but this did not reach statistical significance (OR = 0.13; P = 0.11).

Aged↗
PubMed1999

Risk factors for nosocomial candiduria due to Candida glabrata and Candida albicans.

The aims of this study were to analyze the clinical characteristics and risk factors associated with catheter-associated candiduria due to Candida glabrata and due to Candida albicans and to compare patients with candiduria due to C. glabrata or C. albicans (cases) with controls. Controls were a randomly chosen sample of inpatients with Foley catheters for whom urine cultures were negative for Candida species. Univariate and multivariate analyses were performed. There were 40 cases of C. glabrata candiduria and 289 cases of C. albicans candiduria. Factors strongly associated with both C. albicans candiduria and C. glabrata candiduria were female gender (P <. 05) and being in the intensive care unit (P <. 01). Fluconazole use (adjusted odds ratio, 4.37; P <. 01) and quinolone use (adjusted odds ratio, 3.16; P <. 01) were specifically associated with C. glabrata candiduria but not with C. albicans candiduria. In conclusion, patients receiving fluconazole treatment are at risk of developing C. glabrata candiduria.

Aged↗
PubMed1999

Simple strategy for direct identification of medically important yeast species from positive blood culture vials.

We compared direct inoculation of the Auxacolor yeast identification system from positive blood culture vials to standard identification with the API 20C AUX (API 20C), using 44 prospectively collected clinical specimens and 25 seeded blood culture vials. Direct inoculation of the Auxacolor system was accurate and more rapid than standard identification with the API 20C.

Blood↗
PubMed1996

Influence of age, gender, and menstrual cycle on the normal electrogastrogram.

OBJECTIVES: Dyspeptic symptoms, which are more prevalent in females, are associated with gastric myoelectric and motor abnormalities. Age, gender, and menstrual cycle affect gastric emptying, but their effects on gastric myoelectric activity are not well characterized. The aim of this study was to determine the effects of age, gender, and menstrual cycle on gastric myoelectric activity. METHODS: Healthy subjects (34 male, 49 female; ages 20-79 yr) underwent cutaneous electrogastrography with 60-min fasting and 60-min postprandial recordings. Premenopausal females were studied during days 1-3, 8-10, and 18-20 after onset of menses. Dominant slow wave frequency (DF), power of the DF, and percent time the DF was in a 2- to 4-cpm rhythm were determined for fasting and postprandial periods. RESULTS: The DF, power of the DF, and percent time the DF was in a 2- to 4-cpm rhythm increased from the fasting to the postprandial period. The postprandial increase in the DF was less in females (5.3 +/- 1.2%) than in males (13.0 +/- 2.6%; p < 0.01). In premenopausal females, the DF increased from fasting to the postprandial period for days 1-3 (6.6 +/- 1.5%; p < 0.01) and 8-10 (6.6 +/- 2.3%; p < 0.01), but not during days 18-20 of the menstrual cycle (1.3 +/- 1.8%). The postprandial frequency increase in DF was less for male subjects > or = 60 yr (3.8 +/- 4.0%) than for males < 60 yr (14.6 +/- 2.8%; p < 0.05). CONCLUSIONS: The DF of the electrogastrogram is affected by age, gender, and phase of the menstrual cycle. The influence of these factors should be recognized when interpreting electrogastrograms in symptomatic patients.

Adult↗
PubMed1994

Nonoperative management of esophageal strictures following esophagomyotomy for achalasia.

The optimal management of reflux-induced esophageal strictures that occur after esophagomytomy for achalasia is uncertain. This paper presents our experience with the nonsurgical treatment of postesophagomyotomy strictures in achalasia patients using endoscopic dilation and gastric acid suppression. Six patients with achalasia who had undergone prior esophagomyotomy subsequently developed recurrent dysphagia and were found to have an esophageal stricture. Esophagrams typically showed a markedly dilated esophagus with a narrowed, sharply angulated gastroesophageal junction. Esophageal manometry confirmed esophageal aperistalsis and, when measured, the LES pressure was < 5 mm Hg. Endoscopy showed esophageal inflammation and a fixed stricture at the gastroesophageal junction. Strictures were dilated under direct visualization using through-the-scope balloon dilators. Patients began gastric acid suppressive treatment at the same time. Five patients who remained symptomatic underwent repeat endoscopy, which demonstrated improvement in esophagitis. Dilation was then repeated with a larger balloon dilator. Over a mean follow-up period of 3.8 years, the average number of repeat dilations per patient was 3.6 (range: 0-12). All patients had symptomatic improvement and weight gain. No patient required surgery. We conclude that esophageal strictures after esophagomyotomy for achalasia can be safely treated using endoscopic dilation and gastric acid suppression, thus avoiding the need for reoperation.

Aged↗
PubMed1989

The effects of heparin on rifampin activity against Staphylococcus epidermidis biofilms.

Rifampin shows unique antimicrobial activity against Staphylococcus epidermidis biofilms, although in the in vitro situation rifampin resistance emerges rapidly by the selection of preexisting resistant mutants present in a small number in any large bacterial population. Fresh peritoneal dialysis solution is synergistic with rifampin suppressing rifampin resisters. The antimicrobial properties of rifampin are affected by heparin and protamine in entirely different directions. Heparin blocks the action of rifampin whereas protamine is synergistic producing a total bactericidal outcome. Protamine, when combined with heparin, unexpectedly did not influence the ability of heparin to antagonize rifampin. The mechanisms involved are unknown. The results are discussed in terms of known characteristics of the drugs and of the biofilm surface.

Bacterial Adhesion↗