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Biomedical subjects

Michael W Ellis

Publications and source records attributed to Michael W Ellis.

11 recordsLinked to original sources
PubMed2006

Acinetobacter skin colonization of US Army Soldiers.

OBJECTIVE: To evaluate whether skin colonization with Acinetobacter calcoaceticus-baumannii complex exists in a population of healthy, nondeployed US Army soldiers and, if present, how it might relate to the infections seen in current war casualties. DESIGN: We sampled various skin sites of soldiers to test for the presence of A. calcoaceticus-baumannii complex and to establish the prevalence of colonization. We then used ribotyping and antimicrobial susceptibility profiles to compare the isolates we recovered with A. calcoaceticus-baumannii complex isolates from injured soldiers. SETTING: Fort Sam Houston, Texas. PARTICIPANTS: A population of healthy, nondeployed US Army soldiers in training. RESULTS: A total of 17% of healthy soldiers were found to harbor A. calcoaceticus-baumannii complex. However, the strains differed from those recovered from injured soldiers. CONCLUSIONS: Skin carriage of A. calcoaceticus-baumannii complex exists among soldiers before deployment. However, the difference in the strains isolated from healthy soldiers, compared with the strains from injured soldiers, makes it difficult to identify skin colonization as the source of infection.

Acinetobacter baumannii↗
PubMed2006

Efficacy of macrolides and telithromycin against leptospirosis in a hamster model.

Human studies support the use of beta-lactams and tetracyclines in the treatment of leptospirosis. Additional agents from these and other classes of antimicrobials also have in vitro activity against Leptospira species, though corroborating in vivo data are limited or lacking. We evaluated the therapeutic efficacy of azithromycin, clarithromycin, and telithromycin in a lethal hamster model of leptospirosis using Leptospira interrogans serogroup Canicola serovar Portlandvere. A range of dosages for each antimicrobial was given to the infected animals on days 2 through 7 (5 days) of the 21-day survival model. All untreated control animals survived less than 10 days from infection. Ninety to 100% of doxycycline controls, treated for 5 days with 5 mg/kg of body weight of drug, survived to 21 days. Treatment with azithromycin (daily dose: 6.25, 12.5, 25, 50, 100, or 200 mg/kg) resulted in 100% survival at all evaluated doses. Animals receiving 20 mg/kg or more of clarithromycin (daily dose: 1, 5, 10, 15, 20, 40, 60, or 100 mg/kg) had improved survival. Ninety-eight percent of animals treated with telithromycin (daily dose: 1, 5, 10, 15, 20, or 40 mg/kg) survived. We conclude that all agents tested have demonstrated in vivo efficacy in treating acute leptospirosis. These results provide support for further evaluation of macrolide and ketolide antimicrobial agents in human trials.

Animals↗
PubMed2005

Necrotizing staphylococcal pneumonia in a neonate.

Hospitalized neonates are commonly colonized soon after birth with Staphylococcus aureus. The majority of neonates do not develop infectious sequelae; however, premature neonates appear to be more susceptible to serious infections, such as pneumonia. We report a case of an extremely low birth weight infant who developed necrotizing pneumonia due to methicillin-resistant Staphylococcal aureus (MRSA). The MRSA isolate from this neonate is identical to the strains that have been causing primarily community-associated skin and soft tissue infections. The severe course of this patient may be attributed to the presence of the Panton-Valentine leukocidin gene, a well-known virulence factor leading to soft tissue and pulmonary infections.

Humans↗
PubMed2005

Treatment approaches for community-acquired methicillin-resistant Staphylococcus aureus infections.

PURPOSE OF REVIEW: This review addresses therapeutic approaches to community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections, focusing on recently published data in the English-language medical literature dating from June 2004 to July 2005. RECENT FINDINGS: During the reviewed time period, the overall understanding of the epidemiology and virulence of community-acquired MRSA has continued to advance. This same period has also seen numerous works dealing with the newer and emerging anti-staphylococcal antimicrobial agents. Important clinical trials involving linezolid, daptomycin, tigecycline, dalbavancin, and telavancin have been completed. At the same time, owing to the cost of newer agents and the broad susceptibility pattern of community-acquired MRSA, many older antimicrobial agents (long-acting tetracyclines, fluoroquinolones, rifampin, trimethoprim-sulfamethoxazole, and clindamycin) have also been reexamined. SUMMARY: As data accumulates, the newer antimicrobial agents active against community-acquired MRSA continue to demonstrate their value. Despite the appeal and abundant publications involving newer agents, older antimicrobials certainly retain a therapeutic role. Considerable work needs to be done prospectively evaluating older agents for community-acquired MRSA disease. The most important therapeutic intervention for the majority of community-acquired MRSA infections is adequate drainage of purulent fluid collections. Antimicrobial selection for community-acquired MRSA infections should be governed by disease severity, susceptibility patterns (especially based on timely clinical specimen culture), clinical response to therapy, and cost.

Acetamides↗
PubMed2004

Natural history of community-acquired methicillin-resistant Staphylococcus aureus colonization and infection in soldiers.

BACKGROUND: Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen for which the prevalence, risk factors, and natural history are incompletely understood. METHODS: In this prospective observational study, we evaluated 812 US Army soldiers to determine the prevalence of and risk factors for CA-MRSA colonization and the changes in colonization rate over time, as well as to determine the clinical significance of CA-MRSA colonization. Demographic data and swab samples from the nares for S. aureus cultures were obtained from participants at the start of their training and 8-10 weeks later. Over this time period, participants were observed prospectively to monitor for soft-tissue infections. S. aureus isolates were characterized by in vitro examination of antibiotic susceptibilities, mecA confirmation, pulsed-field gel electrophoresis, and Panton-Valentine leukocidin (PVL) gene testing. RESULTS: At the initial sampling, 24 of the participants (3%) were colonized with CA-MRSA, 9 of whom (38%) developed soft-tissue infections during the study period. In contrast, 229 participants (28%) were colonized with methicillin-susceptible S. aureus (MSSA), 8 (3%) of whom developed clinical infections during the same period (relative risk, 10.7; 95% confidence interval, 4.6-25.2; P<.001). At follow-up culture, the CA-MRSA colonization rate dropped to 1.6% without eradication efforts. Previous antibiotic use was a risk factor for CA-MRSA colonization at the initial sampling (P=.03). PVL genes were detected in 66% of 45 recovered CA-MRSA isolates, including all 9 clinical isolates available for analysis. Of subjects hospitalized, 5 of 6 had PVL-positive CA-MRSA infections. CONCLUSIONS: CA-MRSA colonization with PVL-positive strains was associated with a significant risk of soft-tissue infection, suggesting that CA-MRSA may be more virulent than MSSA. Previous antibiotic use may play a role in CA-MRSA colonization.

Abscess↗
PubMed2004

Coccidioidomycosis mimicking ovarian cancer.

BACKGROUND: Dissemination of coccidioidomycosis to the abdominal cavity is rare. No previous case of peritoneal coccidioidomycosis has presented as an adnexal mass. CASE: We report a case of peritoneal coccidioidomycosis mimicking ovarian carcinoma. The patient presented with a complex ovarian mass, ascites, omental caking, and an elevated CA 125. The ultimate diagnosis was not made until frozen section histopathology was performed at staging laparotomy. CONCLUSION: Peritoneal coccidioidomycosis can present with the clinical, radiographic, and serologic features of ovarian cancer. Although essential for diagnosis and staging, radiographic studies and tumor markers have limited specificity. Coccidioidomycosis now joins other benign conditions that comprise the differential diagnosis of patients who present with what seems to be advanced ovarian carcinoma. Infectious diseases consultation is recommended for the management of peritoneal coccidioidomycosis.

Adult↗
PubMed2004

Susceptibility of Leptospira serovars to antimalarial agents.

Leptospirosis has recently been described to cause concomitant infection with malaria. Only doxycycline has proven to have chemoprophylactic and therapeutic efficacy for both malaria and leptospirosis. To assess whether other traditional antimalarial agents have antileptospiral activity, we performed broth microdilution susceptibility testing of 16 Leptospira serovars (6 species/14 serogroups) to various agents. Artemisinin, atovaquone, chloroquine, mefloquine, primaquine, proguanil, pyrimethamine, sulfadoxine, quinine, quinidine, and combinations of atovaquone/proguanil and pyrimethamine/sulfadoxine all had a 90% minimum inhibitory concentration (MIC(90)) > 25 microg/mL (the upper limit of testing). The only agents identified with the potential to treat both infections other than doxycycline (MIC(90) = 1.56 microg/mL) were azithromycin (MIC(90) = 0.002 microg/mL) and clindamycin (MIC(90) = 0.2 microg/mL).

Antimalarials↗
PubMed2002

A case report and a proposed algorithm for the transfer of patients with Stevens-Johnson syndrome and toxic epidermal necrolysis to a burn center.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare cutaneous diseases marked by substantial epidermal denudation and are often complicated by sepsis and multiple organ failure. They are most commonly caused by drug therapy. Patients afflicted with these diseases require care that may exhaust the capabilities of medicine wards and medical intensive care units alike; however, their mortality is reduced when treated at burn centers, which are better equipped to treat extensive skin denudation. We report a case of TEN and propose an algorithm to provide guidance for making the critical decision to transfer patients with SJS and TEN to burn units.

Algorithms↗
PubMedDate not supplied

Comparison of short-course (5 days) and standard (10 days) treatment for uncomplicated cellulitis.

BACKGROUND: Cellulitis is a condition routinely encountered in the primary care setting. No previous study has compared a short (5 days) vs standard (10 days) course of therapy of the same antibiotic in patients with uncomplicated cellulitis. METHODS: We performed a randomized, double-blind, placebo-controlled trial to determine if 5 days of therapy has equal efficacy to 10 days of therapy for patients with cellulitis. Of 121 enrolled subjects evaluated after 5 days of therapy for cellulitis, 43 were randomized to receive 5 more days of levofloxacin therapy (10 days total antibiotic treatment), and 44 subjects to receive 5 more days of placebo therapy (5 days of total antibiotic treatment). Levofloxacin was given at a dose of 500 mg/d. Subjects were not randomized if they had worsening cellulitis, a persistent nidus of infection, a lack of any clinical improvement, or abscess formation within the first 5 days of therapy. The main outcome measure was resolution of cellulitis at 14 days, with absence of relapse by 28 days, after study enrollment. RESULTS: Eighty-seven subjects were randomized and analyzed by intention to treat. There was no significant difference in clinical outcome between the 2 courses of therapy (success in 42 [98%] of 43 subjects receiving 10 days of antibiotic, and 43 [98%] of 44 subjects receiving 5 days of antibiotic) at both 14 and 28 days of therapy. CONCLUSION: In patients with uncomplicated cellulitis, 5 days of therapy with levofloxacin appears to be as effective as 10 days of therapy.

Analysis of Variance↗