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Biomedical subjects

V L Yu

Publications and source records attributed to V L Yu.

At least 235 records · Page 13Linked to original sources
PubMed1983

Nosocomial Legionnaires' disease uncovered in a prospective pneumonia study.

Most hospitals have yet to record a case of nosocomial legionnaires' disease; the importance of isolation of Legionella pneumophila in the water system of such an institution is unclear. We undertook a prospective pneumonia study in tandem at a veterans hospital where legionnaires' disease was known to be endemic and a community teaching hospital where legionnaires' disease had never been documented. Legionella serological tests were performed on all patients with pneumonia; selective culture media and direct fluorescent antibody testing for Legionella were made readily available. Simultaneous environmental surveys for Legionella were performed. At the community hospital, we discovered that 64% of sites in the water distribution system yielded L pneumophila and that 14.3% of nosocomial pneumonias were legionnaires' disease. The epidemiologic implications of these findings are discussed. Options concerning case detection and eradication measures in the face of hospital water contamination with L pneumophila are presented.

Adult↗
PubMed1983

Simultaneous infection with Legionella pneumophila and Pittsburgh pneumonia agent. Clinical features and epidemiologic implications.

Nosocomial pneumonia caused simultaneously by two organisms, Legionella pneumophila and the Pittsburgh pneumonia agent, was documented in seven patients in one institution. In all seven cases, both organisms were demonstrated by isolation from culture or visualization by direct immunofluorescence. Four patients died as a result of pneumonia, including two who received erythromycin therapy. The hospital water distribution system appeared to be the reservoir for both L. pneumophila and Pittsburgh pneumonia agent. These seven cases constituted 26.9 percent and 17.9 percent of the cases of Pittsburgh pneumonia agent and Legionnaires' disease, respectively, at one institution. Given this relatively high incidence of dual infection, it is likely that the mode of transmission for both organisms is identical. Dual infection may account for some cases of antibody response to more than one Legionella species. Historical parallels of the discovery of L. pneumophila and Pittsburgh pneumonia agent are reviewed.

Cross Infection↗
PubMed1983

Synergy with double and triple antibiotic combinations compared.

Combinations of two sets of antibiotics (gentamicin-carbenicillin-rifampicin and trimethoprim/sulphamethoxazole-carbenicillin-rifampicin) were tested against isolates of Pseudomonas maltophilia. An abbreviated checker-board method permitted tests with combinations of all three antibiotics and of each of the possible three pairs in each set. Triple combinations were usually synergistic, whereas 25% of combinations of pairs were antagonistic or additive. The modal degree of synergy was greater with combinations of three antibiotics than with combinations of any two. For any isolate, greater synergy was generally obtained with a triple than with a double combination, and the mean degree of synergy was always greater with triple than with double combinations. It was advantageous to add to double combinations even an antibiotic to which the organism was resistant. Organisms multiply resistant to three antibiotics were also resistant to 25% of combinations of pairs, but never resistant to combinations of all three. Synergy was more likely to be present at all antibiotic ratios with triple than with double combinations. Since ratios at the site of action may differ greatly from that of the administered combination, there would be substantial clinical benefit in identifying sets of antibiotics of which combinations at all ratios showed synergy. The search for these may entail exploring multicomponent combinations and, with conventional methods, this raises a considerable logistic problem. A strategy is therefore proposed, designed to find antibiotic sets showing synergy at all ratios.

Anti-Bacterial Agents↗
PubMed1983

Conceptual obstacles in computerized medical diagnosis.

Despite extensive research and a multitude of computer systems, there is no viable computerized system that is even remotely capable of approaching the skill of an expert human physician. Minor obstacles in the design of a practical system include imprecise medical terminology, the use of nonindependent clinical parameters, incorrect or inaccurate information supplied to the computer, and static representation of a patient's medical history. Major problems that go beyond computer manipulation of data include the requirement for a massive data base, representation of medical knowledge in general rather than specific terms, and physician fallibility in the design of a computer system.

Diagnosis, Computer-Assisted↗
PubMed1983

Pneumonia due to the Pittsburgh pneumonia agent: new clinical perspective with a review of the literature.

We review the current knowledge concerning this newly recognized pathogen, Pittsburgh pneumonia agent (PPA), and present a new, comprehensive perspective of PPA based on our extensive clinical experience: 1) PPA pneumonia is more common and affects a broader range of patients than previously appreciated. 2) In the general population, the disease is not distinguishable from acute pneumonia due to other causes. Because specialized diagnostic tests are required for detection, it is likely that many cases in other hospitals go unrecognized. 3) Diagnosis is important, as erythromycin appears to improve outcome, whereas beta-lactam antibiotics and aminoglycosides, frequently used as empiric therapy for nosocomial bacterial pneumonias, do not. 4) The presence of both PPA and L. pneumophila in the same environmental sites, and the discovery of seven cases of simultaneous infection by both organisms suggest that both organisms are likely to share a common reservoir within the hospital and a common mode of transmission. 5) PPA infection occurs in a more debilitated population than does Legionnaires' disease. This may represent differences in intensity of exposure to the two organisms or may reflect inherent differences in virulence.

Bacterial Infections↗
PubMed1983

Legionella pneumophila contamination of a hospital humidifier. Demonstration of aerosol transmission and subsequent subclinical infection in exposed guinea pigs.

Water from a humidifier located in the hospital was found to be contaminated with Legionella pneumophila, serogroup 1. The source of water for the humidifier was the hospital potable water system. Exposure of culture mediums to the humidifier aerosols yielded L. pneumophila, serogroup 1. Exposure of guinea pigs to humidifier aerosols produced a subclinical infection as demonstrated by seroconversion to L. pneumophila. Seroconversion rate of guinea pigs to L. pneumophila was higher when greater quantities of L. pneumophila were present in the water; a corresponding increase in recovery of the organism from culture mediums exposed to aerosols was also seen. This report shows that mechanically created aerosols of Legionella-contaminated potable water might be the vehicle of transmission of Legionnaires' disease, especially in the hospital setting.

Aerosols↗
PubMed1983

Third-generation and investigational cephalosporins: II. Microbiologic review and clinical summaries.

In vitro susceptibility of Streptococcus pyogenes, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Serratia marcescens, Hemophilus influenzae, Bacteroides fragilis, and Neisseria gonorrhea to three new second-generation and eight third-generation cephalosporins is tabulated. In general, the newer cephalosporins have an extended spectrum of activity against gram-negative bacteria, including Serratia marcescens, Pseudomonas aeruginosa, and Neisseria gonorrhea. They also tend to be active against anaerobes, including Bacteroides fragilis. However, they generally have less activity against gram-positive bacteria when compared with the first- and second-generation cephalosporins. Clinical summaries are given for each of the cephalosporins, with emphasis on the results of comparative clinical trials. These cephalosporins may prove especially useful in nosocomial infections with resistant organisms, intraabdominal infections, febrile episodes in the granulocytopenic patient, and meningitis.

Bacteria↗
PubMed1983

Clinicoradiographic correlation with the extent of Legionnaire disease.

Serial chest radiographs from 34 confirmed cases of legionnaire disease diagnosed between February 1979 and June 1981 were reviewed. Initial involvement was most often a peripheral patchy alveolar infiltrate (76%, 26/34) with progression to consolidative pneumonia in 70% (18/26) of these cases. Initial or eventual involvement of noncontiguous lobes (50%, 17/34) was common. Bilateral changes developed in 50% of cases and bilateral diffuse disease developed in 12%. Pleural effusions attributable to legionnaire disease occurred in 32% of the patients. Definite clearing took longer than 2 weeks in 50% of treated patients. The severity of radiographic abnormality correlated with the presence of Legionella pneumophila detectable in sputum by direct immunofluorescence (p less than 0.001). No correlation of radiographic severity to smoking, immunosuppression, advanced age, race, or underlying disease, nor to symptoms of abdominal pain, diarrhea, neurologic abnormalities or high fever, nor to laboratory data including hyponatremia, leukocytosis, or hematuria was found. A comparative review of the literature is provided.

Adult↗
PubMed1983

Ticarcillin-tobramycin-rifampin: in vitro synergy of the triplet combination against Pseudomonas aeruginosa.

MICs of ticarcillin, tobramycin, and rifampin alone and in combination were determined by a three-dimensional checkerboard method for 33 isolates of Pseudomonas aeruginosa. Twenty-nine of 33 isolates were affected synergistically (FIC index less than 1.0) by the combination of ticarcillin-tobramycin, including 13 of the 16 isolates resistant to ticarcillin and/or tobramycin alone. However, despite fulfilling the criteria for synergy, the MIC of the ticarcillin and/or tobramycin when in combination still exceeded attainable serum concentrations for 12 of the 13 resistant isolates. When rifampin was added to ticarcillin-tobramycin, a synergistic interaction was observed for all 33 isolates. Furthermore, of the 16 isolates resistant to ticarcillin and/or tobramycin, eight were inhibited by attainable concentrations of all three antibiotics in combination. If these results can be confirmed in the clinical situation, application of the three-drug combination of ticarcillin-tobramycin-rifampin might improve survival in selected patients with serious P. aeruginosa infections.

Anti-Bacterial Agents↗
PubMed1983

Pseudomonas stutzeri bacteremia associated with hemodialysis.

Pseudomonas stutzeri bacteremia developed in six patients undergoing hemodialysis. Fever, shaking chills, nausea, and vomiting were observed. All patients recovered, although only two received specific antibiotic therapy. The infections occurred sporadically over a period of nine months. Pseudomonas stutzeri was subsequently isolated from the dialysate that circulates within the hemodialysis machine. The ultimate source was the deionized water that is combined with the liquid concentrate to form the dialysate. Pseudomonas stutzeri could be localized to the top cannister of the dialysis machine but was also isolated throughout the machine, including the bottom reservoir and the recirculating pump. The emphasis on handwashing, strict compliance with disinfection procedures, and elimination of prolonged sitting times for the filled machine after disinfection resulted in no further cases of P stutzeri infection.

Humans↗
PubMed1982

Potable water supply as the hospital reservoir for Pittsburgh pneumonia agent.

Both legionnaires' disease and pneumonia caused by Pittsburgh pneumonia agent (PPA) are endemic in the Veterans Administration Medical Center, Pittsburgh. 85% of cases of legionnaires' disease and 100% of the cases of PPA were acquired in hospital. A selective dye-containing medium which allows visual discrimination of Legionella pneumophila and PPA has been used in a large-scale environmental survey of the hospital. Samples from 53 sites, including hot-water storage tanks, showerheads, mixing valves, and taps from 19 wards, were cultured. PPA was isolated from 2 sites and L. pneumophila from 33 sites. Water from a tap in the surgical intensive-care unit yielded 6 colony-forming units (CFU) of PPA/0.1 ml and 300 CFU of L. pneumophila/0.1 ml after centrifugation. Water from the outlet valve of a hot-water storage tank yielded 10 CFU of L. pneumophila/0.1 ml and when concentrated by centrifugation also yielded 2 CFU of PPA/0.1 ml. PPA and L. pneumophila share the same environmental niche, but isolation of PPA is more difficult. It seems that the reservoir for PPA in the VA Medical Center is the hot-water distribution system. PPA and L. pneumophila were simultaneously isolated from the lung tissue of a patient in this hospital who died of hospital-acquired pneumonia; this finding supports the hypothesis of a common reservoir and mode of transmission for the two organisms.

Cross Infection↗
PubMed1982

Moxalactam therapy. Its use in chronic suppurative otitis media and malignant external otitis.

Moxalactam disodium is a new broad-spectrum antibiotic structurally related to the cephalosporins. Eleven patients with chronic suppurative otitis media with mastoiditis and four patients with malignant external otitis were treated with moxalactam. Pseudomonas aeruginosa was isolated from external ear or mastoid in all patients. Twelve of 15 patients had undergone prior surgical procedures and 11 of 15 had failed recent antibiotic therapy. Three patients with malignant external otitis did not respond to parenteral carboxypenicillin and aminoglycoside therapy. Success rate for chronic suppurative otitis media was 73% as judged by eradication of P aeruginosa and resolution of symptoms 30 days after moxalactam therapy. Two patients with malignant external otitis were cured, and two were unevaluable since they may have died of noninfectious causes. Moxalactam disodium, at a dosage of 9 g/day, may be useful for serious Pseudomonas ear infections, including those refractory to other antibiotic therapy.

Aged↗
PubMed1982

Disseminated listeriosis presenting as acute hepatitis. Case reports and review of hepatic involvement in listeriosis.

We report three cases of disseminated listeriosis that presented as acute hepatitis characterized by striking increase of liver function test values and fever. Peak serum transaminases (SGOT) for each of three patients were 5,380, 2,350, and 443 mu/ml respectively. The correct diagnosis was not suspected in any of the patients until blood and cerebrospinal fluid cultures obtained routinely in the course of evaluation for fever grew Listeria monocytogenes. When antibiotic therapy was instituted, serum transaminase values plummeted in two patients; these two were eventually cured of their infection. The third patient succumbed to his infection; postmortem examination showed miliary abscesses of the liver which revealed L. monocytogenes. Review of the literature for previous reports of hepatic involvement in adult patients with listeriosis shows that hepatitis is an unusual mode of presentation. However, since we observed these three cases over a one-year period, we suspect this may not be an uncommon occurrence.

Ampicillin↗
PubMed1982

Effect of calcium, magnesium, and zinc on ticarcillin and tobramycin alone and in combination against Pseudomonas aeruginosa.

Correlation between in vitro and in vivo test results for synergy between carboxypenicillins and aminoglycosides against Pseudomonas aeruginosa is poor. Although the divalent cation content of culture media is known to affect aminoglycoside susceptibility testing for P. aeruginosa, this effect of divalent cations has not been examined for synergy testing of carboxypenicillin-aminoglycoside interaction against P. aeruginosa. The minimal inhibitory concentrations (MICs) of tobramycin and ticarcillin and the interaction of these drugs in combination were studied by a microtitration method for 36 strains of P. aeruginosa in Mueller-Hinton broth with varying supplements of calcium, magnesium, and zinc. The supplementation of Mueller-Hinton broth to 50 or 100 mg of calcium per liter had a significant effect in increasing the tobramycin MIC (P less than 0.01), as well as decreasing the degree of synergy between ticarcillin and tobramycin (P less than 0.01). Supplementation to 20 mg of magnesium per liter, 1.0 mg of zinc per liter, or both did not significantly affect tobramycin MIC or the interaction of tobramycin and ticarcillin. Supplementation to 50 or 100 mg of calcium per liter rendered any additional effect of magnesium and zinc on aminoglycoside MIC and aminoglycoside-carboxypenicillin interaction negligible. If these results for ticarcillin and tobramycin are confirmed for other carboxypenicillins and aminoglycosides, then the Mueller-Hinton broth used for P. aeruginosa aminoglycoside susceptibility and synergy testing may need to be supplemented only with calcium at a concentration of 50 mg/liter.

Anti-Bacterial Agents↗
PubMed1982

Determination of cefoperazone concentration in serum and muscle tissue with a versatile high-pressure liquid chromatographic method.

A rapid, specific, and reproducible high-pressure liquid chromatographic method was developed for the determination of cefoperazone concentration in serum and tissue. The assay uses a simple methanol extraction, with cefoxitin as the internal standard. The limits of detection are 1 to 150 micrograms/ml; the maximum coefficient of variation is 7.4%. Using the same chromatography column, muBondapak phenyl, and mobile-phase 0.005 M tetrabutylammonium buffer-acetonitrile (80:20), the method can be easily adapted for the analysis of cefoxitin and moxalactam.

Cefoperazone↗
PubMed1982

Isolation of Pittsburgh pneumonia agent from a hospital shower.

Tatlockia (Legionella) micdadei, the Pittsburgh pneumonia agent, was isolated from a hospital shower. Although it was not possible, at the current time, to establish an epidemiological link to disease acquisition, this information may be significant because it provides further evidence that a water-associated reservoir of this organism exists within the hospital.

Hospitals↗