Joseph F. Plouffe

Distribution of Legionella Species and Serogroups Isolated by Culture in Patients with Sporadic Community-Acquired Legionellosis: An International Collaborative Survey

This international collaborative survey identified culture-confirmed legionellosis in 508 patients with sporadic community-acquired legionellosis. Legionella pneumophila constituted 91.5% of the isolates. Serogroup 1 was the predominant serogroup (84.2%), and serogroups 2-13 (7.4%) accounted for the remaining serogroups. The Legionella species most commonly isolated were L. longbeachae (3.9%) and L. bozemanii (2.4%), followed by L. micdadei, L. dumoffii, L. feeleii, L. wadsworthii, and L. anisa (2.2% combined). L. longbeachae constituted 30.4% of the community-acquired Legionella isolates in Australia and New Zealand.

THE ROLE OF ATYPICAL PATHOGENS: MYCOPLASMA PNEUMONIAE, CHLAMYDIA PNEUMONIAE, AND LEGIONELLA PNEUMOPHILA IN RESPIRATORY INFECTION

Infections caused by M. pneumoniae, C. pneumoniae, and Legionella spp. are important causes of community-acquired pneumonia (CAP). In the past decade, considerable new information has come to light concerning these organisms. Despite this, debate continues concerning the syndromic approach to CAP and the scientific merit of lumping these pathogens together. Because the etiologic diagnosis of these pathogens is established only in a minority of cases, the true prevalence tends to be underestimated. In clinical practice, these pathogens are often empirically treated. More rapid and cost-effective diagnostic techniques are needed so that the clinical course of patients with these infections can be better characterized.

Parainfluenza Virus Infection Among Adults Hospitalized for Lower Respiratory Tract Infection

To better define the contribution of human parainfluenza viruses (HPIVs) to lower respiratory tract infection in adults, we tested acute- and convalescent-phase serum specimens from hospitalized adults participating in a population-based prospective study of lower respiratory tract infection during 1991-1992. We tested all available specimens from the epidemic seasons for each virus and approximately 300 randomly selected specimens from the corresponding off-seasons for antibodies to HPIV-1, HPIV-2, or HPIV-3. During the respective epidemic season, HPIV-1 infection was detected in 18 (2.5%) of 721 and HPIV-3 infection in 22 (3.1%) of 705 patients with lower respiratory tract infection. Only 2 (0.2%) of 1,057 patients tested positive for HPIV-2 infection. No HPIV-1 infections and only 2 (0.7% of 281 patients tested) HPIV-3 infections were detected during the off-seasons. HPIV-1 and HPIV-3 were among the four most frequently identified infections associated with lower respiratory tract infection during their respective outbreak seasons.

Comparison of oral fluconazole and clotrimazole troches as treatment for oral candidiasis in patients infected with human immunodeficiency virus.

Thirty-nine adult patients with human immunodeficiency virus infection and oral candidiasis were randomly assigned to receive either one fluconazole capsule (100 mg) or five clotrimazole troches (10 mg each) daily for 14 days. Among 36 evaluable patients, clinical resolution rates were 100 and 65%, respectively (P = 0.018). Mycological eradication rates were 75 and 20%, respectively (P = 0.004). Fluconazole-treated patients were more likely to remain disease free during follow-up than those treated with clotrimazole (P = 0.014 at 2 weeks). Prolonged clinical responses correlated with mycological eradication at the end of therapy (P = 0.043).

Central Nervous System Toxicity Associated with Metronidazole Therapy

Excerpt Metronidazole is a nitroimidazole compound best known as an antimicrobial agent for treating infections caused by susceptible protozoa and anaerobic bacteria. Neurologic side effects attrib...

Clinical Efficacy of Intravenous followed by Oral Azithromycin Monotherapy in Hospitalized Patients with Community-Acquired Pneumonia

ABSTRACT The purpose of this study was to evaluate intravenous (i.v.) azithromycin followed by oral azithromycin as a monotherapeutic regimen for community-acquired pneumonia (CAP). Two trials of i.v. azithromycin used as initial monotherapy in hospitalized CAP patients are summarized. Clinical efficacy is reported from an open-label randomized trial of azithromycin compared to cefuroxime with or without erythromycin. Bacteriologic and clinical efficacy results are also presented from a noncomparative trial of i.v. azithromycin that was designed to give additional clinical experience with a larger number of pathogens. Azithromycin was administered to 414 patients: 202 and 212 in the comparative and noncomparative trials, respectively. The comparator regimen was used as treatment for 201 patients; 105 were treated with cefuroxime alone and 96 were given cefuroxime plus erythromycin. In the comparative trial, clinical outcome data were available for 268 evaluable patients with confirmed CAP at the 10- to 14-day visit, with 106 (77%) of the azithromycin patients cured or improved and 97 (74%) of the comparator patients cured or improved. Mean i.v. treatment duration and mean total treatment duration (i.v. and oral) for the clinically evaluable patients were significantly (P < 0.05) shorter for the azithromycin group (3.6 days for the i.v. group and 8.6 days for the i.v. and oral group) than for the evaluable patients given cefuroxime plus erythromycin (4.0 days for the i.v. group and 10.3 days for the i.v. and oral group). The present comparative study demonstrates that initial therapy with i.v. azithromycin for hospitalized patients with CAP is associated with fewer side effects and is equal in efficacy to a 1993 American Thoracic Society-suggested regimen of cefuroxime plus erythromycin when the erythromycin is deemed necessary by clinicians.

Treatment of Clostridium difficile colitis and diarrhea with vancomycin

Toxigenic Clostridium difficle is the major cause of antibiotic-associated colitis and is susceptible to vancomycin at fecal concentrations achieved with oral therapy. The effect of oral vancomycin was studied in 16 patients with C. difficile-related diarrhea or colitis, 12 of whom had colitis documented by endoscopy, biopsy, and/or barium enema. Four patients had antibiotic-associated diarrhea and possibly antibiotic-associated colitis, because sigmoidoscopy either showed normal results (two patients) or was not performed (two patients). Nineteen episodes of diarrhea were treated with oral vancomycin in two dosage regimens for three to 14 days. Twelve patients received 2 g daily, and four patients initially received 1 g or less per day. Within 48 hours of the start of vancomycin therapy, 14 of 16 patients (87 percent) showed a decrease in temperature, abdominal pain and diarrhea. Diarrhea ceased completely within two days of the start of vancomycin in nine episodes, within three to seven days in six episodes, and within eight to 14 days in the remaining four episodes, and within eight to 14 days in the remaining four episodes. Diarrhea recurred in two of these patients (12 percent) when the drug inciting the initial episode of colitis was given again 42 days or more after vancomycin therapy was stopped; both patients responded again to retreatment with vancomycin. Oral vancomycin is an effective treatment of C. difficile-related colitis and diarrhea.

Azithromycin in the Treatment of Legionella Pneumonia Requiring Hospitalization

Azithromycin is highly active against Legionella pneumophila and has been shown to be efficacious in animal models and in clinical studies of patients with legionnaires disease. This open, prospective, multicenter trial evaluated azithromycin for the treatment of legionnaires disease. Twenty-five hospitalized patients with community-acquired pneumonia and a positive result of a L. pneumophila serogroup 1 urinary antigen assay received monotherapy with intravenous azithromycin (500 mg/day) for 2-7 days, followed by oral azithromycin (1500 mg administered over the course of 3 or 5 days). The mean total duration of intravenous plus oral therapy was 7.92 days. The overall cure rate among clinically evaluable patients was 95% (20 of 21 patients) at 10-14 days after therapy and 96% (22 of 23 patients) at 4-6 weeks after therapy. The results of this study support previously reported data demonstrating that azithromycin is both safe and efficacious for the treatment of hospitalized patients with legionnaires disease.

Potential importance of Legionella Species as etiologies in community acquired pneumonia (CAP)

Large percentages of patients with community acquired pneumonia (CAP) do not have a defined etiology. Between 1992-1993, 99 acute and convalescent sera were collected from patients with CAP of unknown etiology. The sera were tested using an indirect immunofluorescence antibody assay (IFA) against the following antigens: Legionella pneumophila, serogroups 3,5,6 and 7 and L. longbeachae, L. anisa, L. bozemanii and Legionella-Like Amoebal Pathogens (LLAP). A four-fold rise in titer to at least one of the antigens tested, was seen in 14% of patients; 8% to L. bozemanii, 4% to L. anisa, 2% to S. lyticum, 2% to LLAP 10 and 1% each to LLAP 1, 6 and 9. Two patients reacted to several antigens. These results indicate that other species of legionella may be important in the etiology of CAP. L. bozemanii was the organism identified in the majority of these infections. Better diagnostic studies i.e. cultures, serologies and urinary antigen testing, which recognize legionella isolates other than L. pneumophila serogroup 1 need to be developed.

Emerging Therapies for Serious Gram-Positive Bacterial Infections: A Focus on Linezolid

Respiratory tract infections and skin and soft-tissue infections frequently are caused by gram-positive cocci, and treating these infections with standard antibiotics has recently become problematic. Many of the primary pathogens causing these infections are now resistant to current standard treatment regimens. In addition, the frequency of these infections is increasing, particularly among patients with complex medical conditions. Thus, new and effective antimicrobial agents are needed, and many are currently in various stages of development. Linezolid, the first approved oxazolidinone, has enhanced activity against gram-positive organisms. Recent results of 5 large, randomized, phase 3 trials evaluating linezolid for the treatment of community-acquired pneumonia, nosocomial pneumonia, and uncomplicated and complicated skin and soft-tissue infections are encouraging and indicate that linezolid is as effective as standard comparator agents as therapy for these infections. Thus, the recent availability of linezolid offers clinicians a promising new agent for the treatment of serious gram-positive bacterial infections.