Randall S. Edson

General Principles of Antimicrobial Therapy

Antimicrobial agents are some of the most widely, and often injudiciously, used therapeutic drugs worldwide. Important considerations when prescribing antimicrobial therapy include obtaining an accurate diagnosis of infection; understanding the difference between empiric and definitive therapy; identifying opportunities to switch to narrow-spectrum, cost-effective oral agents for the shortest duration necessary; understanding drug characteristics that are peculiar to antimicrobial agents (such as pharmacodynamics and efficacy at the site of infection); accounting for host characteristics that influence antimicrobial activity; and in turn, recognizing the adverse effects of antimicrobial agents on the host. It is also important to understand the importance of antimicrobial stewardship, to know when to consult infectious disease specialists for guidance, and to be able to identify situations when antimicrobial therapy is not needed. By following these general principles, all practicing physicians should be able to use antimicrobial agents in a responsible manner that benefits both the individual patient and the community.

An outbreak of Mycobacterium chelonae infections in tattoos

Nontuberculous mycobacteria infections may occur after cutaneous procedures. Review of the medical records of patients who developed a rash within a tattoo revealed 6 patients with skin infections caused by Mycobacterium chelonae after receiving tattoos by one artist at a single tattoo establishment. The interval between tattoo placement and the skin findings was 1 to 2 weeks. All patients received alternate diagnoses before mycobacterial infection was identified. Skin findings included pink, red, or purple papules; papules with scale; pustules; granulomatous papules; and lichenoid papules and plaques. Histopathologic examination revealed granuloma, lymphohistiocytic infiltrate, or mixed inflammation; acid-fast bacilli stains produced negative results. Diagnosis was made by culture in 3 patients, histopathology in two patients, and clinical/epidemiologic association in one patient. The M chelonae isolates were clarithromycin susceptible, and the infections responded to macrolide antibiotics. Physicians should consider mycobacterial infections in patients with skin findings within a new tattoo.

Rhinoscleroma: A Growing Concern in the United States? Mayo Clinic Experience

Rhinoscleroma is a chronic, progressive, granulomatous infection of the upper airways caused by the bacterium Klebsiella rhinoscleromatis. Although most cases occur in developing countries, recent immigration patterns have led to an increasing number of patients with rhinoscleroma in the United States. Rhinoscleroma may mimic various inflammatory and neoplastic processes, including leprosy, paracoccidioidomycosis, sarcoidosis, basal cell carcinoma, and Wegeners granulomatosis. Current therapy consists of a combination of surgical débridement and prolonged antimicrobial therapy. Rhinoscleroma should be added to the list of opportunistic infections that can occur in patients with human immunodeficiency virus.

Quantitative Blood Cultures in Candidemia

The relationship between quantitative data on peripheral blood cultures and source of infection was studied in 172 episodes of candidemia that occurred in 169 patients. Clinically, the source of candidemia was an intravascular device in 67 episodes, an extravascular source in 73 episodes, and endocarditis in 2 patients; no source was identified for the other 30 episodes. Colony counts were determined in peripheral blood specimens on the first day of candidemia by the lysis-centrifugation system. High-grade and low-grade candidemia were defined as 25 colony-forming units or more per 10 ml and 10 colony-forming units or fewer per 10 ml of blood, respectively. Of 48 episodes of high-grade candidemia, 43 (90%) were associated with an infected intravascular device; therefore, the presence of high-grade candidemia should prompt the removal of intravascular devices. In contrast, 92 of the 112 episodes of low-grade candidemia (82%) had an extravascular or an unidentified source of candidemia. In patients with infections associated with an intravascular device, colony counts declined significantly within 72 hours after removal of the device in the absence of antifungal therapy; failure to decline suggests an alternative source of persistent infection. Quantitative data from peripheral blood cultures may help distinguish intravascular from extravascular sources of candidemia and aid in assessing the response to the removal of infected intravascular devices.

The Aminoglycosides: Streptomycin, Kanamycin, Gentamicin, Tobramycin, Amikacin, Netilmicin, and Sisomicin

Despite the introduction of newer, less toxic antimicrobial agents, the aminoglycosides remain useful in the treatment of serious, hospital-acquired, gram-negative bacillary infections, especially those caused by Pseudomonas aeruginosa. Formidable nephrotoxicity and ototoxicity have limited the use of neomycin to topical or oral administration. Widespread antimicrobial resistance among Enterobacteriaceae has restricted the use of streptomycin and kanamycin to a few specific clinical situations. Gentamicin, tobramycin, and amikacin are active against a wide range of Enterobacteriaceae and many P. aeruginosa organisms. In medical centers where gentamicin resistance is prevalent, amikacin is the aminoglycoside of choice. Fortunately, amikacin resistance has not seemed to increase substantially, even in institutions where usage has been extensive for a long period. No new aminoglycoside has proved to be superior to amikacin.

Polymicrobial cholangitis and kaposi's sarcoma in blood product transfusion-related acquired immune deficiency syndrome

Before presenting to the Mayo Clinic, a 24-year-old white woman had received 35 transfusions of blood products over a 72-hour period in February 1981. Two and one half years later, the diagnosis of polymicrobial cholangitis (Cryptosporidium, Candida albicans, and Klebsiella pneumoniae) was established. Further evaluation demonstrated profound helper T lymphocyte suppression, disseminated Mycobacterium avium-intracellular infection with mycobacteremia, and Kaposis sarcoma of lymphoid tissue, confirming a diagnosis of acquired immune deficiency syndrome (AIDS). This case represents an unusual infectious complication of AIDS. Additionally, this is believed to be the first report of Kaposis sarcoma occurring in a patient with AIDS associated with blood product transfusion.

Problem residents: prevalence, problems and remediation in the era of core competencies.

a S A g The American Board of Internal Medicine (ABIM) has defined the “problem resident” as a learner who demonstrates problem behaviors significant enough to require intervention by program leadership, typically the residency program director or chief resident. It has been over a decade since Yao and Wright’s report on the prevalence of “problem residents” in internal medicine residency training programs. Their survey of program directors reported performance problems in 6.9% of residents. We are unaware of any subsequent large studies in internal medicine of this important topic. Although the term “problem resident” has been used frequently, we will refer to these individuals as “residents in difficulty.” The purpose of this study was to assess internal medicine program director experiences with residents in difficulty in the era of Accreditation Council for Graduate Medical Education (ACGME) competencies.

Disseminated Mycobacterium abscessus infection manifesting as fever of unknown origin and intra-abdominal lymphadenitis : Case report and literature review

Mycobacterium abscessus is a rapidly growing mycobacterium found in soil and water throughout the world. Disease in immunocompetent patients usually consists of localized skin and soft tissue infections. In contrast, disseminated disease is uncommon, usually presents with rash, and almost always occurs in an immunocompromised host. We describe an unusual case of disseminated M. abscessus infection manifesting as fever of unknown origin and intra-abdominal lymphadenitis, but without rash. Our patient responded well to amikacin and clarithromycin therapy. We also review the literature related to the diagnosis and management of this uncommon disease.

Empiric Therapy With Moxalactam Alone in Patients With Bacteremia

Moxalactam was administered (20 mg/kg intravenously every 8 hours) as single-drug empiric antimicrobial therapy to 63 patients with bacteremia who were neither neutropenic nor immunosuppressed. Six patients (10%) had microorganisms that were susceptible to moxalactam and resistant to all other antimicrobial agents tested; two patients (3%) had microorganisms that were resistant to moxalactam and other agents tested. Of these 63 patients, 47 (75%) were cured with moxalactam therapy. Nine patients (14%) had breakthrough bacteremia while receiving other antimicrobial therapy and were cured subsequently with moxalactam therapy alone. The two major risk factors for failure of moxalactam therapy were polymicrobial bacteremia and an extrahepatic intra-abdominal source of infection; these two conditions frequently coexisted. Six of nine patients with polymicrobial bacteremia died. Superinfection (one pseudomonal, five enterococcal) was responsible for 6 of the 16 treatment failures. Enterococcal superinfection occurred exclusively among patients who had received relatively prolonged therapy with moxalactam for extrahepatic intra-abdominal infection, especially intraabdominal abscess. These five patients died, and postmortem examination showed that enterococcal superinfection was the major cause of death in all. Mild, reversible adverse reactions associated with use of moxalactam occurred in 14 of the 63 patients (22%). None had clinically overt bleeding. The use of moxalactam alone seems to be safe and effective and a cost-effective alternative empiric antimicrobial therapy for most patients with bacteremia who are not immunosuppressed or neutropenic and who are not at high risk of having Pseudomonas or polymicrobial bacteremia.

Laboratory-acquired Salmonella typhimurium enteritis:Association with erythema nodosum and reactive arthritis

A ccidental infection of workers in microbiology laboratories has long been recognized as an occupational hazard. Historically, diseases caused by microorganisms of high infectivity and pathogenicity, such as brucellosis, typhoid, tularemia, and tuberculosis, have predominated reports [1]. Laboratory-acquired infection with non-typhi Salmonella has rarely been reported. We report a case of laboratory-acquired Salmonella typhimurium infection associated with erythema nodosum, reactive arthritis, and episcleritis.