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Biomedical subjects

V L Yu

Publications and source records attributed to V L Yu.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rational empiric antibiotic prescription in the ICU.

The prescribing of antibiotics in the ICU is usually empiric, given the critical nature of the conditions of patients hospitalized there. Appropriate antibiotic utilization in this setting is crucial not only in ensuring an optimal outcome, but in curtailing the emergence of resistance and containing costs. We propose that research in the ICUs is vitally important in guiding antibiotic prescription practices and, therefore, the achievement of above-stated goals. There is wide institutional diversity in the relative prevalence of predominant pathogens and their antimicrobial susceptibilities, and within individual ICUs there exist unique patient populations with varying risks for and susceptibilities to infections and specific pathogens. Appropriate antibiotic prescription practices should be formulated based on surveillance studies and research at individual ICUs; these goals can be accomplished utilizing existing resources.

Anti-Bacterial Agents↗
PubMed1999

Nasal carriage of and infection with Staphylococcus aureus in HIV-infected patients.

BACKGROUND: Staphylococcus aureus is a common cause of serious infection in patients infected with HIV. OBJECTIVES: To evaluate risk factors for and quantitative effect of S. aureus infection in HIV-infected patients, with special attention to nasal carriage. DESIGN: Prospective, multihospital cohort study. SETTING: Three tertiary care Veterans Affairs Medical Centers. PARTICIPANTS: 231 ambulatory HIV-infected patients. RESULTS: Thirty-four percent of patients were nasal carriers of S. aureus. Of these patients, 38% were persistent carriers and 62% were intermittent carriers. Twenty-one episodes of infection occurred in 13 patients: Ten were bacteremias (including 2 cases of endocarditis), 1 was pneumonia, and 10 were cutaneous or subcutaneous infections. Seventeen (85%) of these episodes occurred in patients with CD4 counts less than 100 cells/mm3. Recurrent infections occurred in 3 of 7 patients who survived an initial S. aureus infection. The mortality rate was higher among patients with S. aureus infection than among those without infection (P = 0.03). Factors significantly associated with S. aureus infection were nasal carriage, presence of a vascular catheter, low CD4 count, and neutropenia. Molecular strain typing indicated that for 6 of 7 infected patients, the strain of S. aureus isolated from the infected sites was the same as that previously cultured from the nares. CONCLUSION: Nasal carriage is an important risk factor for S. aureus infection in HIV-infected patients. Controlled studies are indicated to determine whether eradication of nasal carriage in a selected subset of patients (for example, those with a low CD4 cell count) might prevent invasive S. aureus infection in patients with HIV infection.

AIDS-Related Opportunistic Infections↗
PubMed1999

Combination antibiotic therapy versus monotherapy for gram-negative bacteraemia: a commentary.

Whether combination antimicrobial therapy is more efficacious than monotherapy for gram-negative bacteraemia remains controversial. Although there are theoretical advantages to combination therapy that are buttressed by in vitro and animal studies, the data from studies of patients with gram-negative bacteraemias have been conflicting. A review of selected clinical studies suggests that combination therapy is associated with improved outcome typically only in severely ill patients and its efficacy may be further limited to those with Pseudomonas aeruginosa, Klebsiella spp. or Enterobacter spp. bacteraemia.

Anti-Bacterial Agents↗
PubMed1998

Treatment options for chronic prostatitis due to vancomycin-resistant Enterococcus faecium.

Prostatitis due to vancomycin-resistant enterococci has not been previously described. Reported here is a case of chronic prostatitis due to Enterococcus faecium, resistant to vancomycin, ampicillin, ciprofloxacin and doxycycline, in a 42-year-old liver transplant recipient. Treatment with a combination of rifampin and nitrofurantoin for 6 weeks resulted in long-lasting cure. Other antimicrobial agents active in vitro against vancomycin-resistant enterococci, such as quinupristin/ dalfopristin and chloramphenicol, are unlikely to achieve sufficient prostatic tissue levels to be successfully utilized for treatment of this condition.

Adult↗
PubMed1998

Nosocomial legionnaires' disease discovered in community hospitals following cultures of the water system: seek and ye shall find.

BACKGROUND: The reservoir for hospital-acquired legionnaires' disease is the water distribution system. The Allegheny County (Pa.) Health Department recommended environmental cultures for all health care facilities for the prevention of hospital-acquired Legionella infection including facilities with no known cases of legionnaires' disease. METHODS: Environmental cultures of hot water tanks, faucets, and showerheads were performed in six health care facilities according to health department guidelines. If hot water tanks, faucets, or showerheads yielded Legionella, monitoring with Legionella culture and urinary antigen was performed for all cases of nosocomial pneumonia. RESULTS: Legionella was isolated from the water distribution system in 83% (five of six) of facilities. Three facilities dropped out of the study; two decided to disinfect the water and one had no Legionella in the water system. The other three facilities all discovered cases of legionnaires' disease during the 1-year study period after introduction of Legionella testing. L. pneumophilia, serogroups 1, 3, and 5, caused 12 cases of hospital-acquired legionnaires' disease. Positive diagnostic tests included: 10 of 12 (83%) urinary antigen, 6 of 8 (75%) respiratory cultures, and 2 of 5 (40%) serology. Molecular typing confirmed that the source of infection was the water supply in two hospitals. CONCLUSION: Routine environmental cultures for Legionella in the water distribution system are recommended even if the hospital had not previously recognized cases of hospital acquired legionnaires' disease. The Allegheny County Health Department guidelines were inexpensive to implement and resulted in the discovery of cases that would have otherwise been undiagnosed.

Cross Infection↗
PubMed1998

Comparative activity of ciprofloxacin, ofloxacin, levofloxacin, and erythromycin against Legionella species by broth microdilution and intracellular susceptibility testing in HL-60 cells.

Animal lung macrophages or human peripheral blood mononuclear cells have been used for testing intracellular activity of anti-Legionella antibiotics; such studies are labor intensive such that comparative antibiotic studies for the many Legionella species are few. We evaluated a human monocyte cell line (HL-60) as an alternative model. HL-60 (1.5 x 10(6) cells/well) was differentiated into adherent cell and infected with 1.5 x 10(7) CFU of Legionella pneumophilia (L. pneumophilia). Erythromycin and quinolones, ciprofloxacin, ofloxacin, and levofloxacin were added to cells at 1 and 8 x MIC. Percent (%) inhibition ratios equal to total L. pneumophila with agent divided by L. pneumophila without agent x 100 were determined at 48 h; lower ratios implied greater potency. By broth dilution in buffered yeast extract broth, the most potent agents against L. pneumophila were (MIC): ciprofloxacin (0.015-0.03), ofloxacin (0.015-0.03), levofloxacin (0.015-0.03), erythromycin (0.125-1.0 microgram/mL). In the intracellular model, the most potent inhibitors of L. pneumophila multiplication at 8 x MIC were (in order of potency) levofloxacin (24.2%), ciprofloxacin (30.6%), ofloxacin (37.1%), and erythromycin (55.0%). All the quinolones were highly active and significantly more potent against L. micdadei and L. bozemanii when compared to L. pneumophila.

Anti-Bacterial Agents↗
PubMed1998

Do in vitro susceptibility data predict the microbiologic response to amphotericin B? Results of a prospective study of patients with Candida fungemia.

Outcome for 105 patients with candidemia treated with amphotericin B was correlated with amphotericin B in vitro susceptibility results. Thirty-three patients had microbiologic failure, which was defined as persistence of Candida in the bloodstream despite > or = 3 days of amphotericin B. Amphotericin B minimum inhibitory concentrations (MICs) were determined by the National Committee for Clinical Laboratory Standards methodology. After determination of MICs, the minimal lethal concentrations (MLCs) were determined. The isolates tested yielded a narrow range of amphotericin B MICs (0.06-2 microg/mL); only 5% (5/105) exhibited MICs > or = 1 microg/mL. The MLC range, on the other hand, was significantly broader (0.125 to > 16 microg/mL); 24% (25/105) exhibited MLCs > or = 1 microg/mL. The strongest predictor for microbiologic failure was 48-h MLC (P < .001), followed by 24-h MLC (P = .03) and 48-h MIC (P = .11). A resistant break point for amphotericin B of > 1 microg/mL for MLC and > or = 1 microg/mL for MIC could be inferred from this study.

Amphotericin B↗
PubMed1998

Intermittent use of copper-silver ionization for Legionella control in water distribution systems: a potential option in buildings housing individuals at low risk of infection.

One copper-silver ionization system was sequentially installed onto the hot-water recirculation lines of two hospital buildings colonized with Legionella pneumophila, serogroup 1. A third building with the same water supply and also colonized with Legionella served as a control. Four weeks after activation of the system, distal site positivity for Legionella in the first test building dropped to zero. After operating for 16 weeks, the system was disconnected and installed onto the second test building. Twelve weeks of disinfection reduced the distal site positivity for Legionella in the second test building to zero. Legionella recolonization did not occur in the first test building for 6-12 weeks and in the second test building for 8-12 weeks after inactivation of the system. The control building remained Legionella-positive throughout the experimental period. A significantly higher copper concentration was found in the biofilm taken from a sampling device than in that from water. This is likely to be the reason that the copper-silver ionization system had the residual effect of preventing early recolonization. Our study raises the possibility that one copper-silver unit could be rotated among several buildings to maintain a Legionella-free environment. Such an approach may be cost-effective for buildings housing individuals at low risk for contracting legionnaires' disease.

Biofilms↗
PubMed1998

Activity of azithromycin, clarithromycin, roxithromycin, dirithromycin, quinupristin/dalfopristin and erythromycin against Legionella species by intracellular susceptibility testing in HL-60 cells.

We evaluated a human monocyte cell line (HL-60) as a model for testing the intracellular activity of anti-Legionella antibiotics; 1.5 x 10(6) HL-60 cells/well were differentiated into adherent cells and infected with 1.5 x 10(7) cfu of Legionella pneumophila. The most active agents against L. pneumophila as judged by broth dilution MICs were (in order of activity) azithromycin, clarithromycin, roxithromycin, quinupristin/dalfopristin, erythromycin and dirithromycin. The most active inhibitors of L. pneumophila intracellular multiplication were (in order of activity) azithromycin, erythromycin, quinupristin/dalfopristin, roxithromycin, dirithromycin and clarithromycin. All the agents were highly active against Legionella micdadei and Legionella bozemanii when compared with L. pneumophila.

Anti-Bacterial Agents↗
PubMed1998

Pulmonary infiltrates in the surgical ICU: prospective assessment of predictors of etiology and mortality.

A prospective cohort study of 129 consecutive patients developing pulmonary infiltrates in the surgical ICU was conducted to determine the predictors and outcome of pulmonary infiltrates. Most common etiologies of pulmonary infiltrates were pneumonia (30%), pulmonary edema (29%), acute lung injury (15%), and atelectasis (13%). Enteral nutrition was associated with a significantly lower incidence of acute lung injury as compared with pneumonia (22% vs 58%, p = 0.012). Patients with liver disease were significantly more likely to have pulmonary infiltrates due to acute lung injury as compared with other etiologies (p = 0.02). Clinical pulmonary infection score (Pugin score) > 6 virtually excluded acute lung injury, pulmonary edema, or atelectasis as etiologies of pulmonary infiltrates. Nosocomial Haemophilus/pneumococcal pneumonia occurred significantly earlier in the ICU as compared with Gram-negative (p = 0.05) or methicillin-resistant Staphylococcus aureus pneumonia (p = 0.01). Pneumonia in trauma patients was significantly more likely to be due to Haemophilus/pneumococcus as compared with all other ICU patients (54% vs 0%, p = 0.0004). These data have implications for treatment of patients with nosocomial pneumonia in the ICU.

APACHE↗
PubMed1998

Legionella: a major opportunistic pathogen in transplant recipients.

Legionella have a predilection for infecting immunocompromised patients, and transplant recipients have the highest risk. Legionella spp have been the most common cause of nosocomial pneumonia among transplant recipients at selected medical centers. Diagnosis is dependent on the ability of the clinical microbiology laboratory to isolate the organism by culture; therefore, the disease is easily overlooked. The mode of transmission of Legionella pneumophila is likely aspiration in transplant recipients. Clinical manifestations are similar to that of other bacterial pneumonias, although diarrhea is often prominent. The quinolone antibiotics (especially ciprofloxacin) are the antibiotics of choice because, unlike the macrolides or rifampin, they do not interact with the immunosuppressive agents used to counter rejection. Prevention of nosocomial legionellosis involves disinfection of the hospital's potable water system. Effective disinfection methods include superheat and flush or copper-silver ionization; hyperchlorination is no longer recommended. Routine culture surveillance directed at the hospital water supply for Legionella is mandatory in hospitals caring for transplant patients.

Humans↗
PubMed1998

Disinfection of water distribution systems for Legionella.

Hospital-acquired legionnaires' disease arises from the presence of Legionella in hospital water systems. Legionella not only persists in hot water tanks but is also found in the biofilm throughout the entire water distribution system. Conditions within water systems that promote Legionella colonization include water temperature, configuration and age of the hot water tank, physicochemical constituents of the water, plumbing materials, and commensal microflora. Hospital-acquired legionnaires' disease has been prevented by instituting control measures directed at the water distribution system. These include superheat-and-flush, copper/silver ionization, ultraviolet light, instantaneous heating systems, and hyperchlorination. Each of the above disinfection methods has been proven to be effective in the short-term, but long-term efficacy has been difficult due to limitations associated with each method. The complexities of Legionella disinfection, including advantages and disadvantages of each method, are reviewed. A successful Legionella prevention program requires cooperation and communication among hospital administrative personnel, engineers, and infection control staff. Routine environmental surveillance cultures for Legionella are the critical component for successful long-term disinfection. Culture results document the efficacy of the disinfection method and alert the hospital staff to consider Legionella in hospitalized patients with pneumonia.

Cross Infection↗