PubMed Health⌕ Search

Biomedical subjects

Leonard B Johnson

Publications and source records attributed to Leonard B Johnson.

14 recordsLinked to original sources
PubMed2006

Emergence of community-associated methicillin-resistant Staphylococcus aureus infection among patients with end-stage renal disease.

OBJECTIVE: To evaluate the frequency of infections due to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains among our patients with end-stage renal disease. DESIGN: Prospective observational clinical and laboratory study of patients in 2005. Molecular features of isolates recovered from these patients were compared with those of isolates recovered in 2000 from patients with end-stage renal disease. SETTING: A 600-bed urban academic medical center. PATIENTS: Thirty-two patients with end-stage renal disease and MRSA infection at the time of hospitalization from 2005 were evaluated. For comparison, laboratory analysis was performed for 17 MRSA isolates recovered from patients with end-stage renal disease in 2000. RESULTS: The patients from 2005 were more likely than the patients from 2000 to have infection with strains that carried the staphylococcal cassette chromosome (SCC) mec type IV complex (50% vs 11.8%; relative risk, 4.25 [95% confidence interval, 1.17-25.98]; P = .012) and the Panton-Valentine leukocidin toxin genes (25% vs 0%; P = .038). Eight patients from 2005 were infected with a strain that is identical to MRSA clone USA300 in terms of molecular type and presence of SCCmec type IV and Panton-Valentine leukocidin genes. Among the patients from 2005, those infected with SCCmec type IV strains (ie, CA-MRSA strains) and those infected with SCCmec type II strains (ie, healthcare-associated MRSA [HA-MRSA] strains) were similar with respect to demographic characteristics, risk factors, and outcomes. CONCLUSIONS: We documented an increased proportion of infections with CA-MRSA strains, including clone USA300, among our population of patients undergoing dialysis. Patients infected with CA-MRSA strains and HA-MRSA strains were similar with respect to presenting illness and outcomes.

Bacterial Toxins↗
PubMed2006

Community-associated methicillin-resistant Staphylococcus aureus causing chronic pneumonia.

A young woman presented with pneumonia of a 3-month duration with predominantly nodular pulmonary infiltrates. Methicillin-resistant Staphylococcus aureus was identified in multiple cultures of sputum specimens. According to findings of pulsed-field gel electrophoresis, the isolate was identical to USA 300 and carried a type IV Staphylococcus cassette chromosome mec type IV gene and the genes for Panton-Valentine leukocidin.

Adult↗
PubMed2006

Clinical and laboratory features of community-associated methicillin-resistant Staphylococcus aureus: is it really new?

OBJECTIVE: To review the epidemiologic and molecular characteristics of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Detroit, Michigan, to assess the risk factors for infection and the response to therapy. DESIGN: Prospective clinical and laboratory study of 2003-2004 CA-MRSA isolates. Molecular features were compared with CA-MRSA isolates from 1980. SETTING: A 600-bed urban academic medical center. PATIENTS: Twenty-three patients with CA-MRSA infections from 2003-2004 were evaluated. In addition, laboratory analysis was performed on 13 CA-MRSA isolates from 1980. MAIN OUTCOME MEASURES: Laboratory analysis of isolates included antimicrobial susceptibility testing, pulsed-field genotyping, testing for Panton-Valentine leukocidin (PVL) genes, and staphylococcal cassette chromosome mec typing. RESULTS: Patients were predominantly young African American males and presented with skin and soft-tissue infections. All isolates were resistant to erythromycin and highly susceptible to other agents. Patients were generally treated successfully with combination incision and drainage and systemic antibiotics. Among the 23 isolates, 20 (87%) were the same strain. This strain carried the staphylococcal cassette chromosome mec type IV and PVL genes and is genetically identical to USA 300. Thirteen isolates of patients from our community who presented with CA-MRSA infections in 1980 represented a single clone that is unique compared with the 2003-2004 isolates. This strain carried staphylococcal cassette chromosome mec type IVA but did not carry the PVL genes. CONCLUSIONS: In our community, CA-MRSA is largely due to a single clone with a type IV mec gene and PVL gene. The type IV staphylococcal cassette chromosome mec type can be demonstrated in CA-MRSA isolates from a remote period, suggesting that earlier outbreaks were not related to healthcare exposure.

Academic Medical Centers↗
PubMed2006

Persistence in Staphylococcus aureus bacteremia: incidence, characteristics of patients and outcome.

Staphylococcus aureus bacteremia often persists. The reasons for persistence and its outcome are poorly defined. We conducted a prospective-observational study among 245 consecutive S. aureus (MRSA: n=125; MSSA: n=120) bacteremias (>or=1 positive blood cultures (BC)) among 234 adults (18-103-y-old; median=59 y) hospitalized during 1 January 2002-31 December 2002 at a 600-bed teaching hospital. Measurements included bacteremia duration, complication-rate (metastatic infection, relapse or attributable mortality) and outcome. Bacteremia duration was measured based on follow-up BC among 193 patients and estimated based on symptoms resolution in the rest. Measured (1-59 d; median=2) and estimated (median=1 d) duration correlated (r=0.885) though positive follow-up BC was often detected without fever (57/105 patients, 54.3%). Persistence (defined as bacteremia for >or=3 d) was noted in 84 cases (38.4%). Complication-rate increased steadily with bacteremia duration (6.6%, 24.0% and 37.7% in bacteremia for 1-2, 3 and >or=4 d, respectively; p=0.05). Cox regression analysis revealed that bacteremia duration correlated positively with endovascular sources (p=0.006), vancomycin treatment (p=0.016), cardiovascular prosthesis (p=0.025), metastatic infections (p=0.025) and diabetes (p=0.038). It is concluded that persistent bacteremia is a feature of S. aureus infection, irrespective of oxacillin susceptibility, associated with worse outcome. Risk factors include endovascular sources, cardiovascular prosthesis, metastatic infections, vancomycin treatment and diabetes. Patients at risk may benefit from novel treatment strategies.

Adolescent↗
PubMed2005

Time to positivity in Staphylococcus aureus bacteremia: possible correlation with the source and outcome of infection.

BACKGROUND: Staphylococcus aureus bacteremia often persists and causes metastatic infections. It is unknown whether the time between blood culture incubation and growth detection (i.e., the time to positivity) in a continuously monitored system--a probable surrogate marker of bacteremia severity--correlates with outcome. METHODS: We performed a prospective, observational study involving adult inpatients who had S. aureus bacteremia between 1 January 2002 and 30 June 2003 at a 600-bed teaching hospital. Measurements included time to positivity in initial blood culture series, duration of bacteremia, rate of metastatic infection, and outcome. RESULTS: A total of 376 S. aureus bacteremias (> or = 1 positive blood culture result) were reported for 357 patients aged 18-103 years (median age, 59 years); 64 bacteremias were excluded because blood was drawn after antibiotic therapy was started (n = 59) or through an intravascular catheter (n = 5). The source of infection was identified in 244 series (78.2%). Metastatic infection was detected in 25 bacteremias (8.0%). The mortality rate was 25.6%. The duration of bacteremia (determined in 251 series) was 1-59 days (median duration, 1 day; 70th percentile, 3 days). The time to positivity ranged from 4.2 to 98.2 h (median time to positivity, 15.5 h) and was significantly shorter for patients with an endovascular source of infection (14.9+/-5.4 vs. 19.5+/-10.6 h; P < .0005), extended duration (i.e., > or = 3 days) of bacteremia (14.1+/-4.2 vs. 18.6+/-9.2 h; P < .0005), and metastatic infection (12.9+/-5.9 vs 18.0+/-9.3 h; P = .007). Analysis of a range of cutoff values demonstrated that a time to positivity of < or = 14 h yielded the best sensitivity and specificity for predicting the source and outcome of infection. Logistic regression analyses revealed that a time to positivity of < or = 14 h was an independent predictor of an endovascular source of infection (P < .0005), extended bacteremia (P < .0005), metastatic infection (P < .0005), and attributable mortality (P = .017). CONCLUSIONS: Time to positivity in S. aureus bacteremia may provide useful diagnostic and prognostic information. Growth of S. aureus within 14 h after the initiation of incubation may identify patients with a high likelihood of endovascular infection sources, delayed clearance, and complications.

Adolescent↗
PubMed2005

Second-generation azole antifungal agents.

The development of the triazole antifungal agents in the 1980s and 1990s greatly enhanced physicians' ability to treat fungal infections due to the lower toxicity of these agents compared with previous antifungal therapies. Despite the addition of these agents, there continues to be limited therapeutic choices for a number of mycoses that cause significant disease in humans. Three new agents (voriconazole, posaconazole and ravuconazole) have been developed which appear to have expanded antifungal activity compared with prior azoles. This review discusses the pharmacology, in vitro and in vivo activity, clinical studies and toxicities of these second-generation azoles. Presently, only voriconazole is available clinically and is indicated for the treatment of esophageal candidiasis, invasive aspergillosis, and refractory infections with Scedosporium apiospermum and Fusarium spp. Posaconazole and ravuconazole are still in development for human use.

Animals↗
PubMed2004

Frequency of reduced vancomycin susceptibility and heterogeneous subpopulation in persistent or recurrent methicillin-resistant Staphylococcus aureus bacteremia.

Vancomycin susceptibility was checked in isolates from initial and final blood samples obtained from 22 patients with persistent or recurrent methicillin-resistant Staphylococcus aureus bacteremia. The minimum inhibitory concentration of vancomycin was determined using Etest and found to have increased in 2 pairs of isolates, and results of screening in 4 mu g vancomycin and a modified population analysis profile suggested heteroresistance in 3 isolates (13.6%). Heteroresistance is not a common cause of persistent or recurrent bacteremia.

Anti-Bacterial Agents↗
PubMed2003

Voriconazole: a new triazole antifungal agent.

Voriconazole is a second-generation azole antifungal agent that shows excellent in vitro activity against a wide variety of yeasts and molds. It can be given by either the intravenous or the oral route; the oral formulation has excellent bioavailability. The side effect profile of voriconazole is unique in that non-sight-threatening, transient visual disturbances occur in approximately 30% of patients given the drug. Rash (which can manifest as photosensitivity) and hepatitis also occur. The potential for drug-drug interactions is high and requires that careful attention be given to dosage regimens and monitoring of serum levels and effects of interacting drugs. Voriconazole has been approved for the treatment of invasive aspergillosis and refractory infections with Pseudallescheria/Scedosporium and Fusarium species, and it will likely become the drug of choice for treatment of serious infections with those filamentous fungi.

Antifungal Agents↗
PubMed2003

Staphylococcus aureus bacteremia: compliance with standard treatment, long-term outcome and predictors of relapse.

The long-term outcome of compliance with standard treatment recommendations for Staphylococcus aureus bacteremia was assessed. Cases of S. aureus bacteremia at our institution over a 2-y period were reviewed and follow-up performed by review of subsequent admissions or contact with primary care physicians. We encountered 226 cases (age 64.7 +/- 15.8 y) and most (171/226, 75.7%) had no removable source. In-hospital mortality rate was 32.7% (74/226). Follow-up of 104/152 (68.4%) survivors (for 386.7 +/- 449.8 d) revealed 23.1% (24/104) relapses: recurrent bacteremia (n = 19), distant site (n = 3) and local recurrence (n = 2). Most relapses (21124; 87.5%) occurred within 90 d of therapy. Relapse rate was higher with vancomycin treatment (20148 vs. 4/56; p < 0.001), bacteremia for > or = 3 d (9/20 vs. 15/84; p = 0.001), and failure to remove the source (6/7 vs. 6/22; p = 0.006). Vancomycin effect was independent of oxacillin susceptibility. Treatment for less than the standard 2-week duration among 19 patients with short duration of bacteremia (< 3 d) did not increase relapse rate (1/19; 5.3%). Duration of bacteremia, vancomycin therapy and failure to remove the source were predictors of relapse. Prospective studies are needed to determine if S. aureus bacteremias of short duration can be treated for 2 weeks or less, and define the optimal duration for prolonged bacteremia when vancomycin is used.

Aged↗
PubMed2003

Changing epidemiology of community-onset methicillin-resistant Staphylococcus aureus bacteremia.

OBJECTIVES: To review cases of community-onset Staphylococcus aureus bacteremia and to evaluate whether the risk factors and epidemiology of methicillin-resistant S. aureus (MRSA) bacteremia have changed from early reports. DESIGN: Retrospective case-comparison study of community-onset MRSA (n = 26) and methicillin-susceptible S. aureus (MSSA) (n = 26) bacteremias at our institution. SETTING: A 600-bed urban academic medical center. PATIENTS: Twenty-six patients with community-onset MRSA bacteremia were compared with 26 patients with community-onset MSSA bacteremia. Molecular analysis was performed on S. aureus isolates from the 26 MRSA cases as well as from 13 cases of community-onset S. aureus bacteremia from 1980 and 9 cases of nosocomial S. aureus bacteremia from 2001. RESULTS: The two groups were similar except that patients with MRSA bacteremia were more likely to have presented from a long-term-care facility (26.9% vs 4%; P = .05) and to have had multiple admissions within the preceding year (46% vs 15%; P = .03). Clamped homogeneous electric fields analysis of MRSA isolates from 1982 revealed predominantly that one clone was the epidemic strain, whereas there were 14 unique strains among current community-onset isolates. Among current nosocomial isolates, 3 patterns were identified, all of which were present in the community-onset cases. CONCLUSIONS: Previously described risk factors for MRSA acquisition may not be helpful in predicting disease due to the polyclonal spread of MRSA in the community. Unlike early outbreaks of MRSA in patients presenting from the community, current acquisition appears to be polyclonal and is usually related to contact with the healthcare system.

Academic Medical Centers↗
PubMed2002

Staphylococcus aureus in a single positive blood culture: causes and outcome.

Single positive culture was encountered in 61/235 patients (26%) with Staphylococcus aureus in blood culture over a 2-y period. It represented either true bacteremia (n = 52 cases; 85.2%) or contamination (n = 9; 14.8%). In comparison to cases with < or = 2 positive cultures, these patients did not have less severe disease or a lower incidence of complications.

Adult↗
PubMed2002

Uterine granulomas: clinical and pathologic features.

We retrospectively studied the clinical and pathologic features of uterine granulomas over a 10-year period. Granulomas were detected in 30 women, 22 to 81 years old, in the cervix (n = 12/1,090 cervical specimens; 1.1%) or uterine corpus (n = 18/12,000 uterine specimens; 0.15%). They were discovered during evaluation of abnormal bleeding, cytologic specimens, or other gynecologic conditions. None of the patients had constitutional symptoms. These granulomas were often focal (n = 25 [83%]), exhibiting features of foreign body-type (n = 17 [68%]); or they were diffuse (n = 5 [17%]), all with negative acid-fast bacilli or fungal stains and sometimes necrotizing (2 [40%]). Focal granulomas were highly associated with a preceding biopsy or surgery (22/25 vs 14/53 age-matched control subjects). Follow-up of 28 patients (median, 16 months) showed that 27 remained healthy; only 1 patient developed generalized lesions consistent with sarcoidosis 16 months later Uterine granulomas are rare. They are eitherfocal, related to previous biopsy or surgery, or diffuse, usually representing local reaction without an obvious cause. Association with infection or systemic granulomatous disorders is uncommon.

Adult↗