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Victor L Yu

Publications and source records attributed to Victor L Yu.

At least 19 recordsLinked to original sources
PubMed2006

Quantitative cultures for diagnosing ventilator-associated pneumonia: a critique.

The diagnosis of ventilator-associated pneumonia has been clouded by uncertainty, because a reference standard has never been established. The use of invasive procedures to obtain respiratory tract samples for culture, with quantitation of the bacteria isolated, has been the approach most commonly advocated. Quantitation of bacteria from lower respiratory tract specimens can be used to distinguish colonization from infection. We review the invasive procedures (bronchoalveolar lavage, protected specimen brushing, nonbronchoscopic bronchoalveolar lavage, and blinded bronchial sampling), the methods of quantitation used, the types of catheters used, the sample collection methods, and the criteria used as cutoffs for the quantitative cultures. Quantitation of lower respiratory tract samples is inherently unstable from a mathematical perspective, given the variability in the volume of fluid instilled and reaspirated and the magnitude and complexity of the area being sampled. We also briefly review the use of quantitation for bacterial infections other than pneumonia, including urinary tract infection and catheter-related bacteremia. The variability in both the methods and reference criteria in the studies reviewed show that the quantitation approach is neither standardized nor evidence based.

Bacteremia↗
PubMed2006

Problem pathogens: paediatric legionellosis--implications for improved diagnosis.

Legionnaires' disease is an established and frequent cause of pneumonia in adults but is thought to be a rare cause in children. We reviewed the medical literature for cases of Legionnaires' disease in children and analysed the epidemiology, clinical characteristics, and treatment. 76 cases of legionella infection in children were identified. In 56%, diagnosis was made with culture methodology. 46% were community-acquired infections. 51.5% were under 2 years of age. 78% of the patients had an underlying condition such as malignancy. Fever, cough, and tachypnoea were the most common symptoms. The overall mortality rate was 33% and was higher in immunosuppressed children and in children younger than the age of 1 year. Patients who were treated empirically with anti-legionella therapy had a notably lower mortality rate compared with patients on inappropriate therapy (23%vs 70%). In 88% of hospital-acquired cases, an environmental link to potable water colonised with legionella was identified. We found no clinical features unique to Legionnaires' disease in children that would allow differentiation from pneumonia due to other respiratory pathogens. Awareness of legionella as a potential cause of paediatric pneumonia is particularly important because infection can be severe and life threatening and antimicrobial therapy often used for empirical therapy in children is not effective against legionella. In any case of pneumonia unresponsive to antibiotics, Legionnaires' disease should be considered and specific diagnostic tests to verify this diagnosis should be done. As legionella diagnostic tests become more widely applied, we predict that legionellosis may appear as an emerging infectious disease in children.

Adolescent↗
PubMed2006

Severe pneumococcal pneumonia: new strategies for management.

PURPOSE OF REVIEW: Streptococcus pneumoniae is the leading cause of community-acquired pneumonia worldwide and is the most likely causative pathogen in patients with community-acquired pneumonia admitted to the intensive care unit. Bacteremic pneumococcal pneumonia is an advanced stage of severe pneumococcal pneumonia. Improvement in the management of bacteremic pneumococcal pneumonia has the potential for improving the survival for severe pneumococcal pneumonia. RECENT FINDINGS: Non-culture methods, especially the Binax urinary antigen test, can increase the diagnostic yield for pneumococcal pneumonia, allowing targeted antimicrobial therapy (specifically penicillin). In-vitro resistance to penicillin has increased over the past decade; however, it has not led to clinical failure when used for pneumococcal pneumonia. SUMMARY: Hospitalized patients with community-acquired pneumonia should have blood cultures obtained to confirm the possibility of bacteremic pneumococcal pneumonia. Based on pharmacodynamic properties, parenteral penicillin remains the drug of choice to treat pneumococcal pneumonia regardless of in-vitro resistance. Combination antimicrobial therapy will likely improve survival of patients with bacteremic pneumococcal pneumonia among the subset of critically ill patients.

Adult↗
PubMed2005

Isolation of Staphylococcus aureus from the urinary tract: association of isolation with symptomatic urinary tract infection and subsequent staphylococcal bacteremia.

BACKGROUND: Staphylococcus aureus is frequently isolated from urine samples obtained from long-term care patients. The significance of staphylococcal bacteriuria is uncertain. We hypothesized that S. aureus is a urinary pathogen and that colonized urine could be a source of future staphylococcal infection. METHODS: We performed a cohort study of 102 patients at a long-term care Veterans Affairs facility for whom S. aureus had been isolated from clinical urine culture. Patients were observed via urine and nasal cultures that were performed every 2 months. We determined the occurrence of (1) symptomatic urinary tract infection concurrent with isolation of S. aureus (by predetermined criteria), (2) staphylococcal bacteremia concomitant with isolation of S. aureus from urine, and (3) subsequent episodes of staphylococcal infection. RESULTS: Of 102 patients, 82% had undergone recent urinary catheterization. Thirty-three percent of patients had symptomatic urinary tract infection at the time of initial isolation of S. aureus, and 13% were bacteremic. Eight-six percent of the initial urine isolates were methicillin-resistant S. aureus. Seventy-one patients had follow-up culture data; 58% of cultures were positive for S. aureus at > or =2 months (median duration of staphylococcal bacteriuria, 4.3 months). Sixteen patients had subsequent staphylococcal infections, occurring up to 12 months after initial isolation of S. aureus; 8 late-onset infections were bacteremic. In 5 of 8 patients, the late blood isolate was found to have matched the initial urine isolate by pulsed-field gel electrophoresis typing. CONCLUSIONS: S. aureus is a cause of urinary tract infection among patients with urinary tract catheterization. The majority of isolates are methicillin-resistant S. aureus. S. aureus bacteriuria can lead to subsequent invasive infection. The efficacy of antistaphylococcal therapy in preventing late-onset staphylococcal infection in patients with persistent staphylococcal bacteriuria should be tested in controlled trials.

Aged↗
PubMed2005

Management of nonsevere pneumonia in military trainees with the urinary antigen test for Streptococcus pneumoniae: an innovative approach to targeted therapy.

BACKGROUND: The drug of choice for treatment of Streptococcus pneumoniae infection is generally a penicillin (including amoxicillin). Targeted therapy is, however, rarely used, because results of definitive diagnostic tests for pneumonia are not available for several days. Thus, broad-spectrum antibiotics are used for empirical treatment of pneumonia to cover both typical and atypical pathogens. Our purpose was to assess the usefulness of a strategy of targeted antimicrobial therapy based on the results of a rapid urinary antigen test for S. pneumoniae. METHODS: Military trainees with pneumonia were prospectively assigned to 2 groups: patients with positive urinary antigen test results who were treated with amoxicillin (1000 mg 3 times per day), and patients with negative urinary antigen test results who were treated with clarithromycin (500 mg 2 times per day). The duration of therapy was 5-10 days for both groups. RESULTS: A total of 219 evaluable patients were enrolled in the study. The most common causes of pneumonia were S. pneumoniae, Chlamydia pneumoniae, and Mycoplasma pneumoniae. Patients with positive urinary antigen test results had illness of greater severity at the time of study entry. Twenty-two percent of patients had positive urinary antigen test results (i.e., the amoxicillin group), and 78% had negative urinary antigen test results (i.e., the clarithromycin group). The clinical success rates were 94% for the clarithromycin group and 90% for the amoxicillin group (P = not significant). None of the patients who were classified as having treatment failure died. Resolution of clinical manifestations was slower for patients with pneumococcal pneumonia defined by a positive urinary antigen test result. CONCLUSIONS: The urine antigen test allowed targeted use of a penicillin (amoxicillin) for young immunocompetent individuals with nonsevere, community-acquired pneumonia. Clarithromycin was highly effective against both S. pneumoniae pneumonia and pneumonia due to atypical pathogens.

Adolescent↗
PubMed2005

A proactive approach to prevention of health care-acquired Legionnaires' disease: the Allegheny County (Pittsburgh) experience.

BACKGROUND: The Allegheny County Health Department (ACHD) in Pennsylvania distributed the first guidelines for prevention and control of health care-acquired Legionnaires' disease (LD) by 1995. The proactive approach advocated in the guidelines differed notably from that of the Centers for Disease Control and Prevention (CDC) by recommending routine environmental testing of the hospital water distribution system even when cases of health care-acquired Legionnaires' disease had never been identified. OBJECTIVES: Our purpose was to (1) evaluate the impact of the ACHD guidelines on the Legionella diagnostic and preventive practices of health care facilities in Allegheny and surrounding counties and (2) compare the incidence of health care-acquired LD before and after issuance of the ACHD guidelines. METHODS: CDC case reports of LD from 1991 to 2001 were tabulated and compiled by the ACHD Infectious Disease Unit and the Association for Professionals in Infection Control and Epidemiology, Inc, Three Rivers Chapter. A survey was distributed to 110 hospitals and long-term care facilities in the region. The results were analyzed as occurring either in the preguideline period (1991-1994) or postguideline period (1995-2001). RESULTS: A significant decrease in the number of health care-acquired cases was demonstrated between the preguideline (33%) and postguideline (9%) periods (P=.0001). In contrast, community-acquired cases increased from 67% pre guideline to 91% post guideline. A total of 71% of the facilities were colonized with Legionella. Disinfection of the water distribution system was initiated by 44% of facilities. Use of urinary antigen testing significantly increased from 40% pre guideline to 79% post guideline (P=.0001). CONCLUSIONS: Health care-acquired LD declined significantly after the issuance of guidelines for prevention and control of health care-acquired LD. The decline was associated with health care facilities performing routine environmental monitoring of their water distribution systems followed by the initiation of disinfection methods if indicated. Two unanticipated benefits were (1) cases of LD in the community and long-term care facilities were uncovered as a result of increased availability of Legionella tests and (2) litigation and unfavorable publicity involving ACHD hospitals ceased.

Cross Infection↗
PubMed2005

Comparative activity of quinolones, macrolides and ketolides against Legionella species using in vitro broth dilution and intracellular susceptibility testing.

The comparative in vitro activity of quinolones (trovafloxacin, gemifloxacin, levofloxacin, ciprofloxacin, moxifloxacin and grepafloxacin), ketolides (ABT-773 and telithromycin) and macrolides (clarithromycin, azithromycin and erythromycin) were evaluated against Legionella pneumophila by broth dilution and an HL-60 intracellular model. The MIC90 of the quinolones, clarithromycin and ABT-773 were more than eight times lower than for erythromycin. Telithromycin, ABT-773 and azithromycin had significantly greater intracellular activity against L. pneumophila than erythromycin at 1xMIC and 8xMIC. The rank order of intracellular activity against L. pneumophila serogroup 1 was quinolones>ketolides>macrolides. Clinical trials to determine the clinical efficacy of ketolides for the treatment of Legionnaires' disease are warranted.

Anti-Infective Agents↗
PubMed2005

Legionnaires' disease in long-term care facilities: overview and proposed solutions.

Pneumonia is a leading cause of morbidity and mortality in nursing home patients. In acute care hospitals, there is considerable evidence to indicate that Legionnaires' disease is a significant cause of nosocomial pneumonia, the source of which is the potable water system. A relatively limited amount of data exists as to the role of Legionnaires' disease as a cause of pneumonia acquired in long-term care residents. Several lines of evidence suggest that Legionnaires' disease may be an important but underrecognized cause of pneumonia in long-term care residents. These include reports of outbreaks, prospective studies of community-acquired pneumonia that include nursing home patients, and prospective studies of individual long-term care facilities linking Legionnaires' disease to colonization of the potable water system with Legionella. Multiinstitutional studies combining environmental and clinical surveillance for Legionella are needed to further confirm the relationship between colonization of potable water and the occurrence of disease in the long-term care facilities. Until these studies are completed, it is recommended that individual facilities undertake annual sampling of the potable water system for Legionella, coupled with introduction of the rapid Legionella urinary antigen test should L. pneumophila serogroup 1 be found.

Community-Acquired Infections↗
PubMed2005

Fluconazole MIC and the fluconazole dose/MIC ratio correlate with therapeutic response among patients with candidemia.

We tested 32 Candida isolates recovered in the early 1990s from the bloodstreams of patients with candidemia for in vitro susceptibility to fluconazole and determined if MIC and/or the daily dose of fluconazole/MIC ratio correlated with the response to therapy. This is a unique data set since 87.5% (28/32) of patients were treated with fluconazole doses now considered to be inadequate (</=200 mg), which contributed to high therapeutic failure rates (53% [17/32]). The geometric mean MIC and dose/MIC ratio for isolates associated with therapeutic failure (11.55 mug/ml and 14.3, respectively) differed significantly from values associated with therapeutic success (0.95 mug/ml and 219.36 [P = 0.0009 and 0.0004, respectively]). The therapeutic success rates among patients infected with susceptible (MIC </= 8 mug/ml), susceptible-dose dependent (S-DD) (MIC = 16 or 32 mug/ml), and resistant (MIC >/= 64 mug/ml) isolates were 67% (14/21), 20% (1/5), and 0% (0/6), respectively. A dose/MIC ratio >50 was associated with a success rate of 74% (14/19), compared to 8% (1/13) for a dose/MIC ratio </=50 (P = 0.0003). Our data suggest that both fluconazole MIC and dose/MIC ratio correlate with the therapeutic response to fluconazole among patients with candidemia. In clinical practice, dose/MIC ratio might prove easier to interpret than breakpoint MICs, since it quantitates the effects of increasing fluconazole doses that are alluded to in the S-DD designation.

Adolescent↗