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Biomedical subjects

V L Yu

Publications and source records attributed to V L Yu.

At least 163 records · Page 9Linked to original sources
PubMed1991

Legionella infection.

As specialized laboratory tests became more widely available, Legionella species were found to be common causes of nosocomial and community-acquired pneumonia. Patients with chronic lung disease and organ transplants are at greatest risk. Clinical manifestations are non-specific, although fever greater than 39 degrees C and diarrhea are common. Erythromycin remains the antibiotic of choice, although many alternative agents are available. Once cases are discovered, a search for the organism in water distribution systems and respiratory equipment can be fruitful. Disinfection of water distribution systems by superheating and flushing or by hyperchlorination is feasible.

Erythromycin↗
PubMed1991

Legionellosis.

Legionella is a common cause of community- and hospital-acquired pneumonia. New information on the pathogenesis of infection and the host immune response is reviewed. Specialized laboratory tests, especially culture, are necessary for diagnosis since the clinical presentation is nonspecific. New antimicrobial agents and innovative approaches to disinfection of water distribution systems are presented.

Disinfection↗
PubMed1991

Pseudomonas aeruginosa bacteremia in patients undergoing liver transplantation: an emerging problem.

In our institution, Pseudomonas aeruginosa bacteremia appeared to occur with increasing frequency in patients undergoing liver transplantation. We thus conducted a prospective study to define risk factors and outcome in these patients. Over a 19-month period 6% of liver transplants were followed by Pseudomonas bacteremia. The mean age was 46 years (range, 24 to 67 years). The interval between transplantation and onset of bacteremia was 3 to 372 days (mean, 80). The incidence of Pseudomonas bacteremia in liver transplants was three times that of other transplants (heart, lung, kidney). Ninety one percent of infections were nosocomial. Polymicrobial bacteremia occurred in 30% of episodes. The portal of entry was respiratory in 30%, abdominal in 35%, and biliary in 13%. Four patients had recurrent Pseudomonas bacteremia: liver abscess (1), biliary obstruction (2), subhepatic abscess (1). Survival at 14 days was 70%. Survival rates were significantly lower for patients with hypotension, on mechanical ventilators, and increasing severity of illness (p less than 0.05). Survival was higher when bacteremia occurred within the first 30 days after transplantation compared to after 30 days. A large number (43.4%) of Pseudomonas bacteremias occurred after transplant surgery of biliary tract manipulation, while the patient was receiving a prophylactic regimen of cefotaxime and ampicillin. P. aeruginosa is an important pathogen in the liver transplant recipient; prevention may be possible for a subgroup of patients with the use of prophylactic antibiotics with activity against P. aeruginosa.

Adult↗
PubMed1990

Hepatitis B and hepatitis B vaccine requirements in schools of nursing in the United States: a national survey.

To ascertain use of the hepatitis B vaccine and occurrence of hepatitis B infection in nursing students, 1152 U.S. nursing schools were surveyed; 54.3% responded. The vaccine was required by 4.2% and recommended by 7.7%. Baccalaureate programs tended to require the vaccine more than the associate degree or diploma programs (p = 0.062). The occurrence of exposure of nursing students to blood and body fluids in the past 5 years was reported by 89.7%. Students in the diploma program had significantly more exposures (98.6%) than those in the associate degree (92.8%) and baccalaureate programs (82.7%; p less than 0.0005). At least one case of hepatitis B in the past 5 years was reported by 6.8%. Development of positive serologic markers in students after exposure to blood was reported by 7.1%. Seropositivity tended to occur in the Southeast and West (p = 0.035) and in cities with a relatively higher incidence of acquired immunodeficiency syndrome (p = 0.075). Diploma programs were significantly more likely to institute appropriate follow-up for students after exposure to blood of patients who were known or unknown carriers of hepatitis B virus (p less than 0.0001). For students exposed to blood of patients whose hepatitis B status was unknown and patients who were known hepatitis B carriers, 19.2% and 8.9%, respectively, reported they performed no follow-up whatsoever. U.S. nursing students are inadequately protected against hepatitis B. Nursing school administrators and faculty should be educated on the risks of hepatitis B infection and the indications and use of the hepatitis B vaccine.

Body Fluids↗
PubMed1990

Disinfection of water distribution systems for legionella: a review of application procedures and methodologies.

Hospital-acquired legionella pneumonia is emerging as a major problem; potable water distribution systems have been shown to be the primary reservoirs for the legionella organisms. As a result, disinfection measures have been developed to eradicate the organism from the hospital water supply. Each disinfection modality differs in its design and application such that choosing an appropriate cost-effective control measure requires careful analysis and planning. We assess in comparative fashion the disinfection modalities of thermal eradication ("heat-and-flush"), instantaneous steam-heating system, chlorination, ultraviolet light irradiation, ozonation and metal ionization. The theoretical bases, the actual procedure or system, the logistics of implementation, the costs and personnel requirements and the advantages and disadvantages are presented for each modality. Criteria for selection of a method, the use of combinations of methods, parameters for installation, pitfalls in implementation and a plan for subsequent environmental surveillance are discussed in detail.

Cross Infection↗
PubMed1990

New and emerging etiologies for community-acquired pneumonia with implications for therapy. A prospective multicenter study of 359 cases.

Three hundred fifty-nine consecutive patients with community-acquired pneumonia admitted to university, community, and VA hospitals underwent a standardized evaluation, including specialized tests for Legionella spp. and Chlamydia pneumoniae (TWAR). The most common underlying illnesses were immunosuppression (36.3%), chronic obstructive pulmonary disease (32.4%), and malignancy (28.4%). The most frequent etiologic agents were Streptococcus pneumoniae (15.3%) and Hemophilus influenzae (10.9%). Surprisingly, Legionella spp. and C. pneumoniae were the third and fourth most frequent etiologies at 6.7% and 6.1%, respectively. Aerobic gram-negative pneumonias were relatively uncommon causes of pneumonia despite the fact that empiric broad-spectrum combination antibiotic therapy is so often directed at this subgroup. In 32.9%, the etiology was undetermined. Antibiotic administration before admission was significantly associated with undetermined etiology (p = 0.0003). There were no distinctive clinical features found to be diagnostic for any etiologic agent, although high fever occurred more frequently in Legionnaires' disease. Clinical manifestations for C. pneumoniae were generally mild, although 38% of patients had mental status changes. Mortality was highest for Staphylococcus aureus (50%) and lowest for C. pneumoniae (4.5%) and Mycoplasma pneumoniae (0%). We document that specialized laboratory testing for C. pneumoniae and Legionella spp. should be more widely used rather than reserved for cases not responding to standard therapy. Furthermore, realization that C. pneumoniae and Legionella spp. are common etiologies for community-acquired pneumonia should affect empiric antibiotic prescription.

Adolescent↗
PubMed1990

Failure of a diagnostic monoclonal immunofluorescent reagent to detect Legionella pneumophila in environmental samples.

Three commercial diagnostic fluorescein-labeled antibodies, one monoclonal and two polyclonal, were compared to evaluate their abilities to detect Legionella pneumophila in environmental samples. The monoclonal conjugate failed to detect L. pneumophila in the 12 environmental samples studied by direct immunofluorescence. In contrast, the two polyclonal conjugates detected L. pneumophila in all 12 samples by both direct and indirect immunofluorescence. However, isolates recovered by culture from the 12 samples demonstrated equal immunofluorescence with all three conjugates. The reason for the failure of the monoclonal antibody to detect L. pneumophila in the environmental samples remains unknown. Laboratories considering the use of the monoclonal conjugate to screen environmental samples for L. pneumophila should be aware of this finding.

Antibodies, Bacterial↗
PubMed1990

Oerskovia xanthineolytica implicated in peritonitis associated with peritoneal dialysis: case report and review of Oerskovia infections in humans.

Oerskovia species are nocardialike bacteria that have been implicated as pathogens only rarely. These organisms are branched, gram-positive bacilli that are oxidase negative, catalase positive, and non-acid fast. Unlike Nocardia species, these organisms are motile, do not produce aerial mycelia, and possess a cell wall with large amounts of galactose. Colonies are bright yellow and produce branched vegetative hyphae on nutrient agar. A 70-year-old patient undergoing chronic ambulatory peritoneal dialysis for end-stage renal dysfunction developed recurrent peritonitis. Five peritoneal fluid cultures and one catheter specimen obtained over a period of two weeks yielded a gram-positive bacillus; Oerskovia xanthineolytica was isolated from all six cultures. Prolonged systemic therapy with gentamicin and vancomycin was unsuccessful in curing the peritonitis, but the infection resolved following removal of the peritoneal catheter. This is the first reported case of peritonitis associated with this microorganism. A review of previously described Oerskovia infections, most of which were associated with foreign bodies, showed that removal of infected foci was usually necessary for cure.

Actinomycetales↗
PubMed1990

Malignant external otitis: utility of CT in diagnosis and follow-up.

Malignant external otitis is a severe bacterial infection of the bone and soft tissues of the base of the skull that is frequently difficult to diagnose. The effectiveness of antibiotic therapy is likewise difficult to assess. Serial computed tomographic (CT) scans were obtained in 11 consecutive patients with malignant external otitis at time of diagnosis and periodically after conclusion of antibiotic therapy. All patients demonstrated abnormalities of the external auditory canal, with or without bone destruction. Soft tissue or fluid in the middle ear and mastoid, around the eustachian tube, and in the parapharyngeal space (both pre- and poststyloid) was seen in greater than 50% of the cases. While remineralization of bone was not seen, soft-tissue disease improved dramatically, and recurrence or persistence could be corroborated by detection of more extensive soft-tissue changes. By delineating the extra- and intracranial extent of disease, serial CT scans enable one to make the diagnosis, determine the extent of infection, document recurrence, exclude progression, and confirm resolution of malignant external otitis.

Blood Sedimentation↗
PubMed1990

Aural irrigation with water: a potential pathogenic mechanism for inducing malignant external otitis?

We hypothesized that the forcible introduction of water containing Pseudomonas aeruginosa into the ear canal of a susceptible host (an elderly diabetic with cutaneous hypoperfusion secondary to microangiopathy) was the inciting factor in the development of malignant external otitis. Tap water irrigation of the ears by a physician preceded the onset of symptoms in 61.5% (8/13) of cases of malignant external otitis. Two control subjects with known diabetes mellitus were matched for each patient by sex and age. Both groups were questioned on the nature and degree of aural water exposure, as well as history of ear disease. There were no significant differences between 13 patients and 26 control subjects for presence of ear disease (hearing loss, chronic infection, prior operations), swimming, showering, bathing, frequency of ear cleaning, or method of ear cleaning (washcloth, cotton applicator). Patients with malignant external otitis had a statistically significant higher incidence of aural irrigation with tap water when compared with control subjects. We suggest that a substantial number of cases of malignant external otitis may be iatrogenic.

Aged↗
PubMed1990

Prognosis of patients hospitalized with community-acquired pneumonia.

PURPOSE: Our purpose was to determine which clinical features predict short-term mortality in patients with community-acquired pneumonia. PATIENTS AND METHODS: We conducted a prospective multicenter study of 347 patients hospitalized in Pittsburgh (the derivation cohort) and 253 hospitalized and ambulatory patients in Boston (the validation cohort) with clinical and radiographic evidence of pneumonia. Patients in the derivation cohort underwent an extensive microbiologic evaluation including bacteriologic sputum culture, blood cultures, direct fluorescent antibody testing for Legionella species, and serologic testing for Mycoplasma pneumoniae, Legionella species, and Chlamydia TWAR. RESULTS: The overall mortality was 18% in the derivation cohort and 13.2% in the validation cohort. We identified five independent predictors of mortality in the derivation cohort: pleuritic chest pain (risk ratio, 0.4; 95% confidence interval [CI], 0.17 to 0.99), mental status changes (risk ratio, 2.6; 95% CI, 1.4 to 4.6), a severe vital sign abnormality (risk ratio, 2.1; 95% CI 1.2 to 3.6), neoplastic disease (risk ratio, 5.0; 95% CI, 2.7 to 9.1), and "high-risk" pneumonia etiology (risk ratio, 2.8; 95% CI, 1.6 to 5.0). A mortality index based on these factors accurately classified patients into five risk classes of increasing mortality. In the derivation cohort, the 6-week mortality rates were 0% in class I, 2.9% in class II, 13.1% in class III, 32.7% in class IV, and 89.5% in class V. There was little deterioration in the predictive accuracy of the model when tested in the validation cohort: mortality was 2.2% in class I, 0% in class II, 13.5% in class III, 33.3% in class IV, and 55.6% in class V. CONCLUSIONS: This prognostic classification may help direct triage decisions, assess appropriateness of care, and guide the design and analysis of therapeutic trials in patients with community-acquired pneumonia.

Adolescent↗
PubMed1989

Efficacy of oral ciprofloxacin plus rifampin for treatment of malignant external otitis.

Malignant external otitis is an invasive pseudomonal infection characteristically afflicting the elderly patient with diabetes mellitus. Therapy has traditionally consisted of the long-term administration of combination parenteral antibiotics, but morbidity and mortality remain substantial despite this therapy. We treated 11 consecutive patients with the oral combination of ciprofloxacin (750 mg twice daily) and rifampin (600 mg twice daily) for 6 to 12 weeks (mean, 8 weeks). Pseudomonas aeruginosa was isolated from ear canal or mastoid, and bone destruction was documented by computed tomography in all patients. Seven patients (64%) had ear irrigation before onset of the infection. Ten patients fulfilled the criteria of both clinical and bacteriologic cure. No serious adverse reaction to either antibiotic was observed. Otalgia and otorrhea responded at a mean of 6 and 4 days, respectively, following the initiation of therapy. The erythrocyte sedimentation rate fell from a mean pretherapy value of 81 mm/h (range, 41 to 138 mm/h) to 18 mm/h (range, 3 to 45 mm/h) after the completion of antibiotic therapy. Minimum inhibitory and bactericidal concentrations established that all organisms were sensitive to ciprofloxacin. Time-kill curve and checkerboard assays failed to demonstrate either synergy or antagonism between ciprofloxacin and rifampin. Serum inhibitory and bactericidal titers showed minimal increase in inhibition and killing of the bacteria with the addition of rifampin. Rifampin did not alter the pharmacokinetics of ciprofloxacin. The successful use of oral antibiotics for this difficult infection may be a major advance. Reduction in antibiotic costs and hospitalization and convenience of oral administration were of notable benefit.

Aged↗
PubMed1989

Antibiotic therapy for Pseudomonas aeruginosa bacteremia: outcome correlations in a prospective study of 200 patients.

PURPOSE AND PATIENTS AND METHODS: We performed a prospective clinical study of 200 consecutive patients with Pseudomonas aeruginosa bacteremias to analyze in vitro susceptibility and synergistic testing of antibiotics the patients received and clinical parameters to assess their relationship to survival. RESULTS: No significant correlation between in vitro susceptibility testing (minimal inhibitory concentrations/minimal bactericidal concentrations) and outcome could be demonstrated. Similarly, improved outcome could not be demonstrated for patients receiving antibiotic combinations that were synergistic in vitro (either time-kill or checker-board) versus those combinations that were not. There was also no correlation between results obtained by time-kill curve and checkerboard synergistic testing, i.e., combinations found to be synergistic by one method were not necessarily synergistic by the other method. Clinical parameters associated with improved survival were a urinary portal of entry and absence of neutropenia. Conversely, survival was significantly decreased when the portal was the respiratory tract. The mortality rate between patients receiving combination therapy (27%) and monotherapy (47%) was significant (p less than 0.02); this significant relationship held true for most subgroups including malignancy, nosocomial infection, and infection site. CONCLUSION: Increasing effort should be placed on ensuring timely administration of combination therapy to patients with P. aeruginosa bacteremia since the use of combination therapy was even more important in determining outcome than was underlying disease.

Adolescent↗
PubMed1989

Disease due to the Legionellaceae (other than Legionella pneumophila). Historical, microbiological, clinical, and epidemiological review.

More than 20 species of the Legionellaceae family of bacteria have been discovered since the discovery of Legionella pneumophila. Thirteen have been implicated as causative agents of pneumonia including the Pittsburgh pneumonia agent (Tatlockia micdadei, Legionella micdadei). Although outbreaks of nosocomial pneumonia in immunosuppressed hosts have been well-described, most cases have occurred sporadically in the community. The spectrum of disease ranges from severe life-threatening pneumonia to a self-limiting febrile illness (Pontiac fever). Isolation from the natural aquatic environment has preceded its discovery as agents of human disease in 6 species, while environmental isolation has not yet been obtained for 3 species implicated in disease. The mode of transmission is uncertain, but cases of dual infection by L. pneumophila and the newer species suggests that the epidemiology of these new organisms will be similar to that of L. pneumophila. The antibiotic of choice appears to be erythromycin. The historical background, epidemiology, microbiology, and clinical manifestations of these newly-discovered organisms are reviewed in comparative fashion.

Humans↗
PubMed1989

Community-acquired Legionnaires' disease.

Legionellae are ubiquitous aquatic organisms. They are unique among the agents commonly responsible for bacterial pneumonia in humans in that they are not part of the normal human flora but are acquired from environmental sources. Prospective studies have shown that legionellae consistently rank among the top three bacteria as etiologic agents of community-acquired pneumonia. The clinical presentation of Legionnaires' disease is not distinguishable from that of other bacterial pneumonias. Culture of respiratory secretions using selective media, combined with one or more rapid diagnostic methods (direct fluorescent antibody staining, radiolabelled DNA probe, or urinary antigen detection) provides a specific diagnosis in the vast majority of cases. Sporadic cases have been linked to legionella colonization of water systems in homes and the work setting. Antibiotics commonly used in the therapy of community-acquired pneumonias, such as beta-lactam agents, are ineffective. Specific therapy with erythromycin reduces mortality to less than 10%.

Anti-Bacterial Agents↗
PubMed1989

Staphylococcus aureus nasal carriage in hemodialysis patients. Its role in infection and approaches to prophylaxis.

Staphylococcus aureus infections remain a major cause of morbidity in hemodialysis patients. Chronic dialysis patients are more prone to staphylococcal infections because of their decreased immunity, increased skin colonization by staphylococci, and the multiple needle punctures required for dialysis. The source of the staphylococci is the anterior nares. Elimination of staphylococcal nasal carriage results in a significantly lower infection rate. Selected clinical studies of topical and oral therapy for eradication of staphylococcal nasal carriage are reviewed. Rifampin has been the most consistently efficacious agent, although emergence of resistance is a potential problem. Trials utilizing newer topical and oral agents for prophylactic eradication of S aureus from the nose are indicated. Promising antibiotics include topical mupirocin, the oral quinolones, and clindamycin.

Anti-Bacterial Agents↗