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V L Yu

Publications and source records attributed to V L Yu.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1989

A pink-pigmented, oxidative, nonmotile bacterium as a cause of opportunistic infections.

We describe two cases of bacteremia due to a pink-pigmented, oxidative, nonmotile, gram-negative, rod-shaped organism. One case occurred in a febrile neutropenic patient and another in a chronically debilitated patient with pancreatic abscess. The first patient was cured with gentamicin and ticarcillin, but the second patient died while receiving cefamandole therapy. The organisms described here are similar to Methylobacterium mesophilicum (Pseudomonas mesophilica) and the "unnamed taxon" organisms. A major difference from M mesophilicum is the lack of methanol utilization. Further distinctions between our isolates and M mesophilicum are the lack of flagella in our organisms, growth at 42 degrees C, growth on MacConkey's agar, lack of acetamide assimilation, and citrate utilization. The lack of flagella is the principle difference between our isolates and those in the unnamed taxon. Both of the isolates were resistant to the cephalosporins, but susceptible to the aminoglycosides, ticarcillin-clavulanic acid, sulfamethoxazole and trimethoprim, and imipenem. With the growing population of immunocompromised and chronically ill patients, these organisms may emerge as important pathogens.

Abscess↗
PubMed1988

Necrotizing otitis externa due to Aspergillus in an immunocompetent patient.

An 85-year-old, nondiabetic man is described with necrotizing (malignant) otitis externa. The patient developed facial nerve paralysis in the presence of a progressive cellulitis and chondritis of the external auditory meatus. Destruction of the bony meatus and mastoid and obliteration of normal soft-tissue planes at the skull base were documented by computed tomographic scans. Aspergillus fumigatus was isolated from the external meatus and deep tissue specimens. Fungal invasion of bone and soft tissue was confirmed histopathologically. Pseudomonas aeruginosa was never isolated. This case is unusual from both the standpoint of etiology and host susceptibility in that the patient had no apparent underlying disease. Amphotericin B and rifampin therapy following radical mastoidectomy halted the progression of disease. Finally, this case illustrates the pitfalls of empiric antibacterial therapy for necrotizing otitis externa without cultural confirmation of the etiologic agent.

Aged↗
PubMed1988

Bacteriologic analysis of wound infection following major head and neck surgery.

Wound infection was studied prospectively in 23 (6.5%) of 354 patients who participated in a series of antibiotic trials during major contaminated head and neck surgical procedures. Polymicrobial infection was identified in 22 (96%) of 23 cases. The most commonly encountered organisms were aerobic bacteria (91%), anaerobes (74%), and fungi (48%). All fungal infections resolved without systemic antifungal therapy. It was, therefore, concluded that the presence of fungus represented colonization. The primary treatment of an infected wound is surgical drainage accompanied by broad-spectrum antibiotic therapy to prevent sepsis. The value of postoperative wound cultures is unclear. The majority of patients who developed wound infection had a variety of organisms that appeared to be unrelated to the prophylactic antibiotic used, as well as to the particular surgery performed.

Anti-Bacterial Agents↗
PubMed1988

Malignant external otitis: insights into pathogenesis, clinical manifestations, diagnosis, and therapy.

Malignant external otitis is an infection of the external ear canal, mastoid, and base of the skull caused by Pseudomonas aeruginosa. The condition occurs primarily in elderly patients with diabetes mellitus. Current theories on pathogenesis and anatomic correlations are reviewed. Severe, unrelenting otalgia and persistent otorrhea are the symptomatic hallmarks of the disease, whereas an elevated erythrocyte sedimentation rate is the only distinctive laboratory abnormality. Iatrogenic causes such as administration of broad-spectrum antibiotics and aural irrigation may play a predisposing role in high-risk populations. The disease can result in cranial polyneuropathies (with facial nerve [VII] paralysis being the most common) and death. The mainstay of treatment is administration of antipseudomonal antibiotics for four to eight weeks. Recurrence is common, and mortality remains at about 20 percent despite antibiotic therapy. Given the increasing longevity of diabetic patients, the frequency of this disease is increasing. Internists, family practitioners, and ambulatory care physicians must now be cognizant of the presenting symptoms, while infectious disease specialists and otolaryngologists need to be appraised of strides in diagnosis and therapy. The role of surgery should be minimized. Use of new diagnostic radiologic modalities and new antipseudomonal antibiotics discussed in this review should lead to improved outcome.

Humans↗
PubMed1988

Gangrenous cellulitis associated with gram-negative bacilli in pancytopenic patients: dilemma with respect to effective therapy.

INTRODUCTION: Gangrenous (necrotizing) cellulitis is a progressive bacterial infection of skin and soft tissue; the infection can spread into subcutaneous tissue with involvement of superficial and deep fascia (necrotizing fasciitis). We describe two pancytopenic patients with polymicrobial gram-negative bacteremia and fulminating gangrenous cellulitis. CASE REPORTS: Pseudomonas aeruginosa was isolated from a localized hemorrhagic area of the face in one patient. The chronology of infection in these two patients is documented in a series of dramatic color photographs. Despite appropriate antibiotic therapy, the infections progressed relentlessly and both patients died. COMMENTS: We discuss the dilemma of establishing the correct diagnosis prior to the appearance of the characteristic cutaneous manifestations of hemorrhagic necrosis and gangrene. Once the diagnosis is established, surgical excision is universally recommended. Unfortunately, bleeding diatheses in pancytopenic patients with co-existing coagulation deficiencies pose logistic obstacles in urgent, real-life situations. The timing and conditions for surgery need to be elucidated in these patients. An approach to this infection is proposed. The utility of frozen-section biopsy of the involved tissue and computed tomographic scans of the involved area remains to be evaluated.

Adult↗
PubMed1988

Malignant external otitis in children.

Malignant external otitis in the pediatric population is primarily a disease of children with chronic illness or immunosuppression. The presence of severe, unrelenting otalgia, otorrhea with isolation of Pseudomonas aeruginosa, a markedly elevated erythrocyte sedimentation rate, and evidence of bone destruction on computed tomography scan should alert the clinician to the diagnosis. Unlike adults, children have a higher incidence of seventh nerve paralysis earlier in the course of the infection. They also manifest more frequent involvement of the middle ear with tympanic membrane destruction. The short interval between the onset of symptoms and facial nerve dysfunction highlights the necessity of prompt diagnosis and institution of anti-Pseudomonas therapy. Our review suggests that this destructive bacterial infection is an emerging clinical entity in children; 73% of the cases have been reported since 1980. Pediatricians should therefore be familiar with the clinical presentation of this treatable infection. Substantial morbidity could be alleviated by prompt diagnosis and early antibiotic treatment.

Child↗
PubMed1988

Legionnaires' disease in the work environment: implications for environmental health.

Legionnaires' disease is a severe pneumonia caused by the bacterium Legionella pneumophila. Outbreaks of Legionnaire's disease have occurred in hotels, hospitals, and homes but had not been reported yet in the work environment. The authors report the occurrence of Legionnaires' disease in three employees of two industrial plants. The potable water in the two plants contained high numbers of Legionella pneumophila. Monoclonal antibody subtyping of environmental and patient isolates of L. pneumophila implicated one of the plants as the source for the disease. L. pneumophila was eradicated from this plant using acidic and caustic scale removers, calcium hypochlorite, and a biocide. A systematic approach to Legionnaires' disease in the work environment, a problem which can be expected to be recognized with increasing frequency, is presented.

Antibodies, Monoclonal↗