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Biomedical subjects

V L Yu

Publications and source records attributed to V L Yu.

265 records · Page 15Linked to original sources
PubMed1977

Onset of tuberculosis after intestinal bypass surgery for obesity. Guidelines for evaluation, drug prophylaxis, and treatment.

The association of tuberculosis after gastrectomy is well documented. Two case reports of tuberculosis developing after jejunoileal bypass for massive obesity are presented, with a review of five previously reported cases. Four of the seven reported patients had tuberculosis infection at extrapulmonary sites. Initial symptoms included fever and acceleration of weight loss. The mean time elapsed from the time of the operation to the diagnosis of tuberculosis was 16 months. Guidelines are given for monitoring patients undergoing jejunoileal bypass with tuberculin skin tests. Indications for isoniazid prophylaxis and multiple drug chemotherapy are given. Serum concentrations of oral antituberculosis drugs must be monitored to ensure adequate absorption.

Adult↗
PubMed1976

Computerized consultation system for selection of antimicrobial therapy.

Mycin, a computer-based consultation system which provides to physicians antimicrobial therapy recommendations for patients with bacterial infections, is described. The consultation program arrives at therapeutic decisions using a built-in knowledge base as well as patient data entered by the physician. The system is capable of explaining its recommendations and answering questions about its reasoning process. The system's knowledge can be updated and corrected easily by infectious disease experts. At present the system is operational within a research setting; its routine use in a clinical setting will require further evaluation of its reliability and effectiveness.

Anti-Infective Agents↗
PubMedDate not supplied

Role of aerobic gram-negative rods, anaerobes, and fungi in wound infection after head and neck surgery: implications for antibiotic prophylaxis.

The prevention of wound infection after major contaminated head and neck surgery is a critical issue for the head and neck surgeon. The proper interpretation of cultures taken from wounds is uncertain. Multiple organisms are invariably isolated from this nonsterile site including indigenous aerobic and anaerobic flora, aerobic gram-negative rods, and fungi. We present evidence from controlled antibiotic trials that demonstrate the pathogenicity of oropharyngeal anaerobic flora. The presence of aerobic gram-negative rods and fungi generally represent colonization and antibiotic coverage need not routinely be directed at these organisms. On the other hand, the antibacterial spectrum of an agent used for head and neck would prophylaxis should include coverage for pathogenic oral flora, namely the gram-positive aerobic cocci (especially streptococci) and anaerobic bacteria.

Anti-Bacterial Agents↗
PubMedDate not supplied

Community-acquired pneumonia caused by Legionella dumoffii in a patient with hairy cell leukemia.

A case of community-acquired pneumonia caused by Legionella dumoffii in a patient with hairy cell leukemia is described. Diagnosis was confirmed by isolation by culture of sputum and broncho-alveolar lavage specimens, positive direct fluorescent antibody stains, and antibody seroconversion from 1:16 (acute) to 1:4096 (six months). The blue white autofluorescence of the L. dumoffii colonies when viewed under ultraviolet light was particularly useful in preliminary identification. The patient recovered from his pneumonia after administration of erythromycin and rifampin. Legionella have been shown to multiply in monocytes and cell-mediated immunity appears to be the primary mechanism of host defense in man. Hairy cell leukemia is characterized by monocyte dysfunction and such patients have a predilection for infection by microbes that are controlled by cell-mediated defenses. We review other cases of community-acquired L. dumoffii pneumonia as well as other cases of Legionella infection in patients with hairy cell leukemia.

Antibodies, Bacterial↗
PubMedDate not supplied

Evaluation of housestaff physicians' preparation and interpretation of sputum Gram stains for community-acquired pneumonia.

OBJECTIVE: To evaluate the preparation and interpretation of sputum Gram stains by housestaff physicians in the assessment of patients with community-acquired pneumonia. DESIGN: A prospective, multicenter study. SETTING: Two university-affiliated hospitals in Pittsburgh. PATIENTS: Ninety-nine cases of clinically and radiographically established pneumonia occurring in 97 patients. Diagnostic test assessment: Housestaff and microbiology personnel prepared a Gram stain for each case of pneumonia. Housestaff assessed the presence and identity of a predominant microbial organism on the slides they prepared. Two senior staff microbiologists, blinded to patient and preparer, evaluated all slides for preparation, sputum purulence, and identification of the predominant organism. Two reference standards were used to assess the sensitivity, specificity, and predictive values of housestaff's Gram-stain interpretations: 1) senior staff microbiologists' determinations of the microbes present using the slides without benefit of culture results, and 2) the etiologic agent derived from results of sputum culture, blood culture, or serology. MEASUREMENTS AND MAIN RESULTS: Housestaff physicians completed a Gram stain in 58% of the pneumonia episodes. Gram stains were not made in 42% of cases, primarily because patients were unable to produce sputum. Fifteen percent of housestaff's smears were judged inadequately prepared, compared with 3% for the laboratory personnel (p less than 0.01). Housestaff obtained purulent sputum samples significantly more often than did nursing personnel (58% versus 38%; p less than 0.01). Housestaff's Gram stains were 90% sensitive for detecting pneumococcus, with a 50% false-positive rate. The sensitivity of the Gram stain was less for identification of Haemophilus influenzae than for identification of Streptococcus pneumoniae. A single antimicrobial agent was chosen as initial therapy for 50% of the patients in whom housestaff identified a predominant organism, compared with 30% in whom a predominant organism was not identified (p less than or equal to 0.05). CONCLUSIONS: Although housestaff obtained purulent sputum samples more frequently than did nursing personnel, they made systematic errors in the preparation and interpretation of Gram-stained slides. Housestaff physicians should receive formal training in the preparation and interpretation of Gram stains; the specific defects elucidated in this study warrant special attention.

Adolescent↗
PubMedDate not supplied

Staphylococcus aureus and other bacteremias in hemodialysis patients: antibiotic therapy and surgical removal of access site.

BACKGROUND: Bacteremia is commonplace in patients undergoing hemodialysis since the vascular access site is a ready source of infection. Mortality is notably high. However, uncertainties exist with respect to therapy including indications for surgical removal of vascular access site and duration of therapy. We therefore conducted a large-scale collaborative study of bacteremia in hemodialysis patients in six US academic medical centers to define the epidemiology of such infections and to address issues of management. PATIENTS AND METHODS: We conducted a prospective observational study over 2 years. Severity of illness at onset of bacteremia was defined by objective criteria. Patients were followed for 90 days to assess late complications including endocarditis and mortality. Univariate and multivariate analyses were used to assess risk factors for mortality. RESULTS: Patients experiencing 127 consecutive episodes of bacteremia were enrolled. The most common cause of bacteremia was Staphylococcus aureus (31%), followed by aerobic gram-negative bacilli (28%) and coagulase-negative staphylococci (13%). Polymicrobial bacteremia occurred in 6% of patients. The most frequent focus of infection was the access site for hemodialysis, although urinary tract, gastrointestinal tract and lung were also implicated. Aerobic gram-negative bacilli and enterococci usually originated from the urinary tract. S. aureus was significantly more likely to cause infection of the access site than other bacteria (p = 0.0001). S. aureus endocarditis was diagnosed in two patients who were receiving antibiotic therapy for S. aureus bacteremia. Removal of the infected access site (shunt, fistula, catheter) was performed for 86% of the patients (95% of the intravenous catheters and 80% of the arteriovenous fistulas/shunts). Overall mortality was 33% at 90 days and was significantly associated with severity of illness at onset of antibiotic therapy and age >60 years. Mortality was not significantly different in patients undergoing surgical removal of infected access site versus those treated with antibiotics alone. CONCLUSION: When S. aureus was isolated from the blood, the access site was the most frequent source. Surgical removal of the access site did not have a notable impact on mortality. Until a randomized trial proves otherwise, it appears that surgical removal of the access site can be individualized. Selected patients who are less severely ill (based on objective criteria) can maintain their hemodialysis access site and be treated with 2 weeks of antibiotic therapy.

Abscess↗
PubMedDate not supplied

Synergy assessed by checkerboard. A critical analysis.

The checkerboard dilution test is widely used for evaluation of in vitro synergy for multiple drugs, although problems in performance, standardization, and interpretation have been noted. A major problem inherent in this commonly used method is the use of twofold dilutions for the antibiotic concentrations. We evaluated an alternative method proposed by Horrevorts and colleagues that preserved the twofold dilution scheme. Giant checkerboards were constructed from a series of component checkerboards using rifampin and minocycline against Staphylococcus aureus. We found that this method improved the stability of the fractional inhibitory concentration (FIC) indices, but required substantially more labor and generated other problems. FIC interpretation and calculation remained compromised by the twofold dilution scheme. We have analyzed the theoretical basis of the checkerboard and its FIC calculation and conclude that the twofold dilution with its exponential increase in dilutions makes this method of synergy evaluation inherently unstable. The principle of examining growth at multiple dilutions of combined antibiotics is valid for assessment of synergy, but newer methods need to be devised.

Drug Synergism↗
PubMedDate not supplied

Factors predisposing to Legionella pneumophila colonization in residential water systems.

Fifty-five homes in the Pittsburgh area were surveyed for the presence of Legionella pneumophila colonization. Hot water tanks, faucets, and showerheads were sampled. Six homes yielded Legionella pneumophila within the water distribution system. Lower water temperatures (less than 48.8 degrees C) within the hot water system were significantly associated with the presence of L. pneumophila colonization. A similar association was found for electric heaters; however, this association may be an indirect one. Water temperatures in electrically heated tanks were significantly lower than in gas-heated tanks. City residences were also more likely to be colonized than suburban residences. Because acquisition of Legionnaires' disease in the community has been linked to colonization of the water supplies in the homes of affected patients, these findings may have clinical implications for susceptible individuals residing in homes with water supplies colonized by L. pneumophila.

Hot Temperature↗
PubMedDate not supplied

Infections caused by Pseudomonas maltophilia with emphasis on bacteremia: case reports and a review of the literature.

Ten cases of Pseudomonas maltophilia bacteremia were identified over a five-year period at the University of Pittsburgh Medical Center. Our experience and a review of the literature show that P. maltophilia can cause a wide spectrum of disease. We present cases of pneumonia and infections of the biliary tract and urinary tract in which the organism was isolated simultaneously from blood. P. maltophilia endocarditis occurs in the context of iv drug abuse or as a postoperative complication of prosthetic valve surgery. Pseudobacteremia from contaminated equipment, disinfectants, and vascular catheters is the newest presentation for P. maltophilia infection. Hospitalization and prior antibiotic therapy are risk factors for serious P. maltophilia infection. Mortality due to P. maltophilia infection is low, despite the notable in vitro resistance of the organism to antibiotics. Trimethoprim-sulfamethoxazole, minocycline, doxycycline, and moxalactam are highly active in vitro against P. maltophilia. The triple combination of trimethoprim-sulfamethoxazole plus carbenicillin plus rifampin has been found to be synergistic in vitro and can be considered for serious infections.

Adult↗
PubMedDate not supplied

Third-generation and investigational cephalosporins: I. Structure-activity relationships and pharmacokinetic review.

The structure-relationships and pharmacokinetic properties of the new second- and third-generation cephalosporins are reviewed. The new second-generation cephalosporins include ceforanide, cefotiam, and cefuroxime. The third-generation cephalosporins include cefmenoxime, cefoperazone, cefotaxime, cefsulodin, ceftazidime, ceftizoxime, ceftriaxone, and moxalactam. These new cephalosporins are semisynthetic analogs with different chemical substitutions on a 7-aminocephalosporanic nucleus. As a result of these chemical modifications, improvements in the antibacterial spectrum as well as pharmacokinetic properties have occurred. In general, the new cephalosporins have longer half-lives, higher and prolonged serum concentrations, and increased cerebrospinal fluid penetration. Selected cephalosporins also have increased biliary tract concentrations. A classification scheme for these new agents, based on generation and susceptibility to Pseudomonas aeruginosa, is presented.

Bacteria↗
PubMedDate not supplied

Recurrent methicillin-resistant Staphylococcus aureus osteomyelitis: combination antibiotic therapy with evaluation by serum bactericidal titers.

OBJECTIVE: To report on a patient with recurrent methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis and bacteremia successfully treated with combination antibiotic therapy. CASE SUMMARY: Two sets of blood cultures from a 55-year-old man with fever, malaise, and low back pain grew MRSA. Radiologic studies of the spine showed bony changes consistent with osteomyelitis. Soon after completing 6 weeks of vancomycin, the patient experienced a recurrence of back pain. Laboratory values included an increase in the sedimentation rate to 53 mm/h and positive blood cultures for MRSA. Vancomycin, gentamicin, and rifampin were administered for 8 weeks. Serum inhibitory and bactericidal titers were more than 1:1024 for both the peak and trough concentrations. Radiologic studies of the spine showed healing osteomyelitis. Two years after completion of antibiotic therapy, the infection has not recurred. DISCUSSION: Antibiotic therapy alone was attempted because the patient was considered a risky surgical candidate. Serum inhibitory and bactericidal titers documented the high in vivo activity of the vancomycin, gentamicin, and rifampin combination. Initiation of vancomycin, gentamicin, and rifampin combination. Initiation of vancomycin therapy led to disappearance of the fever and back pain. Cure was documented by sustained normalization of the erythrocyte sedimentation rate and radiologic evidence of healing. CONCLUSIONS: Combination antibiotic therapy with vancomycin, rifampin, and low-dose gentamicin (1 mg/kg q12h) may be useful for deep-seated tissue infection caused by MRSA.

Anti-Bacterial Agents↗
PubMedDate not supplied

Therapeutic approaches in patients with candidemia. Evaluation in a multicenter, prospective, observational study.

OBJECTIVES: To evaluate the morbidity and mortality of Candida fungemia and to assess the efficacy of low- vs high-dose amphotericin B and fluconazole vs amphotericin B in patients with candidemia. METHODS: Multicenter, prospective, observational study of 427 consecutive patients with candidemia. RESULTS: The mortality rate for patients with candidemia was 34%. The mortality rate for patients with catheter-related candidemia in whom the catheters were retained was significantly higher than that of patients in whom the catheters were removed (41% vs 21%, P < .001). We found no overall difference in mortality in patients treated with low-dose (total amphotericin B dose of < or = 500 mg) (13%) vs high-dose amphotericin B (total amphotericin B dose of > 500 mg) (15%), but the group treated with a low dose had fewer side effects (40%) than those treated with a high dose (55%) (P = .03). Fluconazole was as efficacious as amphotericin B in the therapy of candidemia, even when stratified by risk factors for mortality. Fewer side effects were seen with fluconazole (12%) compared with amphotericin B (44%) (P < .001). CONCLUSIONS: In selected patients with candidemia, low-dose amphotericin B was as efficacious as high-dose amphotericin B. Based on other studies and ours, fluconazole seems to be an alternative therapeutic option to amphotericin B in selected patients.

Aged↗