Dermatologic infections in the immunocompromised (non-HIV) host.

The immunocompromised host's susceptibility to infections often present a difficult diagnostic challenge to the physician. A working knowledge of the host immune defenses and microbiologic complications that can occur when these functions are compromised provides a more focused framework for further evaluation and management. Infections in these patients are often morbid and life-threatening, creating an urgent need for prompt diagnosis. The skin may manifest the first clue(s) of a serious underlying infection. Appropriate workup and diagnosis of cutaneous lesions provide an expeditious, noninvasive, and potentially life-saving approach to the immunocompromised host with a dermatologic infection.

Myonecrosis caused by Edwardsiella tarda: a case report and case series of extraintestinal E. tarda infections.

Edwardsiella tarda is an unusual human pathogen. It is primarily associated with gastrointestinal disease, although recent reports of extraintestinal disease are broadening the current understanding of the clinical spectrum of E. tarda. A series of 11 cases of extraintestinal E. tarda infection is presented, including the first reported case of myonecrosis in an immunocompetent patient. Wound infections were the most common manifestation, and 3 of 5 patients with infected wounds had been exposed to a marine environment. One patient had bacteremia, and the remaining 5 patients developed abscesses that required surgical drainage. Four patients had E. tarda isolated in pure culture, including the patient with myonecrosis. Although it is often difficult to ascertain the contribution of E. tarda to infection when it is isolated as part of a mixed culture, this case series suggests that E. tarda is singularly capable of causing limb- and life-threatening infections.

Allergic bronchopulmonary disease caused by Bipolaris hawaiiensis presenting as a necrotizing pneumonia: case report and review of literature.

We report a case of allergic bronchopulmonary disease caused by Bipolaris hawaiisensis in an immunocompetent host, presenting with symptoms and radiographic findings suggestive of necrotizing pneumonia. Cultures of the plugs and bronchial washing yielded the pathogenic fungi. Laboratory tests revealed eosinophilia and elevation of serum IgE. This patient was successfully treated with steroids, amphotericin B lipid complex, and itraconazole. Review of 10 previously reported cases and their clinical manifestations and treatment are presented.

Unusual manifestations of invasive pneumococcal infection.

Unusual pneumococcal infections occurred frequently in the preantibiotic age but rapidly declined with the advent of the antibiotic era. Unfortunately, the morbidity and mortality associated with invasive pneumococcal disease remain high despite antibiotic therapy and monumental advances in medical technology. The incidence of invasive pneumococcal disease has increased recently because of the onset of the human immunodeficiency virus (HIV) epidemic and the emergence of antibiotic-resistant pneumococcus. Robert Austrian described the clinical triad of pneumococcal pneumonia, meningitis, and endocarditis, a syndrome that now bears his name. Although seen infrequently today, unusual manifestations of pneumococcal infection such as those Austrian reported still occur. A review of these cases is warranted because, as drug-resistant organisms continue to emerge worldwide, more unusual pneumococcal infections will be seen. Streptococcus pneumoniae is responsible for a remarkable array of disease processes; our literature review uncovered 95 different types of unusual pneumococcal infections representing 2,064 cases. Examples of these infections included pancreatic and liver abscesses, aortitis, gingival lesions, phlegmonous gastritis, inguinal adenitis, testicular and tubo-ovarian abscesses, and necrotizing fasciitis. We also reviewed predisposing underlying illnesses and conditions. Alcoholism, HIV infection, splenectomy, connective tissue disease, steroid use, diabetes mellitus, and intravenous drug use remain common risk factors for invasive pneumococcal infections. Currently, multidrug-resistant S. pneumoniae remains susceptible to vancomycin and several new third-generation fluoroquinolones. As what some fear will be a possible postantibiotic era approaches, clinicians must be able to recognize and manage unusual pneumococcal infections.

Pneumococcal disease: a symposium in honor of Robert Austrian, MD--a summary.

The Pneumococcus '97 symposium, convened under the direction bf Dr. Stephan L. Kamholz, brought together a preeminent faculty to discuss the current state of our knowledge about Streptococcus pneumoniae and to honor Dr. Robert Austrian, one of the pioneers in the research into what was once one of the primary killers of humankind. My task here is to summarize these diverse presentations and the articles that evolved from them for publication in this supplement to The American Journal of Medicine.

Systemic lupus erythematosus complicated by necrotizing fasciitis.

A case of necrotizing fasciitis (NF) is described in a 46-year-old woman with recent onset systemic lupus erythematosus (SLE). Deep-tissue infections are more common in SLE patients on high-dose corticosteroids, but, to our knowledge, this is the second case described in association with SLE. Although NF may initially be difficult to diagnose, the presence of marked systemic symptoms out of proportion to the local findings should suggest the correct diagnosis. NF diagnostic criteria, treatment and prognosis are discussed.

A multicenter study of the prevalence and susceptibility patterns of isolates of Streptococcus pneumoniae with reduced susceptibility to penicillin G in Louisiana.

Because of increasing reports of multiple-antibiotic-resistant strains of Streptococcus pneumoniae and associated clinical failures, this study was performed to determine the prevalence of multiresistance among strains from nine Louisiana medical centers. Using a National Committee for Laboratory Standards broth microdilution method, 481 strains were tested. Of these, 70% were penicillin-susceptible (PS), 23% had intermediate minimum inhibitory concentration values to penicillin (I), and 7% were fully resistant to penicillin (PR). The isolation rates (15% to 40% for I strains and 0% to 33% for PR strains) at the various medical centers varied appreciably. The prevalence of penicillin resistance was highest among upper respiratory isolates, while cross-resistance to other antimicrobials varied. The least cross-resistance was noted among PS strains. However, strains with reduced penicillin susceptibility had high levels of cross-resistance. Among I strains, the prevalence of cross-resistance (%) was noted for amoxicillin/clavulanate (6%), cefuroxime (71%), cefaclor (91%), ceftriaxone (13%), cefotaxime (34%), erythromycin (67%), azithromycin (32%), and clarithromycin (32%). For PR strains, the prevalence of cross-resistance was 97% for amoxicillin/clavulanate, cefuroxime, and cefaclor; 67% for ceftriaxone and erythromycin; 89% for cefotaxime; and 69% for azithromycin and clarithromycin. These data emphasize the high prevalence of multiple-antimicrobial-resistance among strains of S pneumoniae with reduced penicillin susceptibility in this geographic area.

Skin and soft tissue infections in critical care.

Clinicians in the critical care setting see extensive, severe, and often necrotizing infection, as well as atypical or unusual infection that can be misdiagnosed, resulting in delays in treatment. Greater numbers of immunocompromised patients are at risk for both types of infection. A thorough understanding of various etiologies and presentations of these infections is essential, as is the ability to discriminate between infectious and noninfectious etiologies.

Leptospiral pneumonia.

Leptospirosis, a spirochetal infection, causes a wide spectrum of disease ranging from asymptomatic infection, or influenza-like symptoms, to severe jaundice and renal failure. Humans become infected through skin or mucous membrane contact with infected animal urine or urine-contaminated water or soil. The most common source of human infection worldwide is rats. However, in the United States, dogs, livestock, wild mammals, and cats are also sources. Once leptospires penetrate mucous membranes or breaks in the skin, they disseminate to all parts of the body. Five to ten percent of those infected will have severe leptospirosis with jaundice, known as Weil's disease. The classical presentation of leptospirosis is that of a biphasic illness. The initial septicemic phase lasts 4 to 7 days and is characterized most commonly as a mild influenza-like illness. During the secondary immune phase, leptospires disappear from the blood and cerebrospinal fluid. However, circulating antibodies cause immune-mediated meningitis, uveitis, rash, and, very rarely, circulatory collapse associated with Weil's disease. Pulmonary involvement occurs in 20% to 70% of patients. The more severe pulmonary manifestations are rare. Although attempts should be made to isolate leptospires from the blood or cerebrospinal fluid, the diagnosis is usually established by serologic tests. The effectiveness of antimicrobial therapy in treating leptospirosis has been difficult to assess because of the high variability of the disease's clinical course, although in severe cases, antibiotic therapy is effective even when treatment is delayed. Prevention is difficult because it is almost impossible to eliminate the large animal reservoir of infection.

Piperacillin/tazobactam in the treatment of community-acquired and nosocomial respiratory tract infections: a review.

Investigators assessed the efficacy and safety of piperacillin/tazobactam therapy in a study of patients with community-acquired lower respiratory tract infections and a study of patients with nosocomial, severe lower respiratory tract infections. Piperacillin 4 g/tazobactam 500 mg was given intravenously every 8 h to 193 hospitalized lower respiratory tract infection patients for a minimum of 5 days. There was a favorable response rate of 97% and eradication of the causative pathogen was documented or presumed in 93% of patients. There was a low incidence of adverse experiences and the combination was well tolerated. Seventy-one intensive care patients with severe lung disease received 4 g piperacillin/500 mg tazobactam intravenously every 6 h; afterward they were given amikacin 7.5 mg/kg every 12 h. Minimum duration of treatment was 5 days. Therapy with piperacillin/tazobactam plus amikacin was well-tolerated, produced a 74% favorable clinical response rate, and eradicated the responsible pathogen in 70% of patients.

Current antimicrobial therapy of anaerobic infections.

The treatment of many anaerobic infections involves antimicrobial therapy, appropriate surgical drainage of abscesses, and debridement of devitalized tissue. Most anaerobic infections are polymicrobial and require treatment with agents active against an array of aerobic and anaerobic bacteria. Bacterial resistance, especially to penicillins and tetracyclines, but also to newer agents of other classes, continues to increase. As a result, treatment with more than one drug is often required. Combination therapy is often necessary in serious infection, and is indicated for empiric treatment before receiving culture results. In the past combination therapy has been the mainstay of antimicrobial therapy, but more recent studies suggest that monotherapy for anaerobic infections may dominate the future. Selection of an agent requires consideration of the site of infection and the most likely etiologic agents. In vitro susceptibility is important, but it is not the only determinant of antimicrobial effectiveness. The pharmacology of the drug--absorption, distribution, concentrations in body fluids and tissues, excretion and metabolism--also plays an important role. The nature and severity of the underlying illness are important factors in selecting empiric therapy. Although it is a clinical judgement, in patients considered to have mild to moderate infections, several factors in selecting antimicrobial agents may be considered, including cost, whereas in patients judged to have severe or life-threatening infections, the most potent agents should be chosen as initial therapy, regardless of cost. Finally, the toxicities of the agent must also be considered.

Unusual manifestations of pneumococcal infection in human immunodeficiency virus-infected individuals: the past revisited.

Although AIDS was largely recognized and defined because of the increased presence of diseases that reflect deficiencies in cell-mediated immunity, susceptibility to common extracellular bacterial pathogens has also been shown to be increased. To our knowledge, adults with concurrent infection due to human immunodeficiency virus (HIV) and Streptococcus pneumoniae whose cases have been described to date have all had pneumococcal pneumonia and/or bacteremia. We describe five cases of HIV-infected patients who had unusual manifestations of pneumococcal infection, which include recurrent exudative pleural effusion, pyopneumothorax, purpura fulminans, mediastinitis with chest wall abscess, and multiple brain abscesses. Such complications of pneumococcal infection occurred more or less commonly in the preantibiotic era, but on the basis of our experience and an exhaustive literature search, these complications have been exceedingly rare in the past few decades. In four of our five patients, the unusual, complicated pneumococcal disease preceded and prompted a search for HIV infection. Because concurrent HIV infection increases the susceptibility to pneumococcal disease, other such cases are likely to be seen.

Anaerobic disease of the lung.

Anaerobic pleuropulmonary infections present in various ways. Aspiration pneumonitis occurs first and may be quite difficult to distinguish from the acute bacterial pneumonia caused by Streptococcus pneumoniae and other organisms. Although aspiration pneumonitis may be self-limiting, sequelae such as lung abscess, necrotizing pneumonia, and empyema can develop. Empiric antimicrobial therapy is now acceptable. The initial choice of antimicrobial agents is based on which pathogens are likely to be involved.

Antibiotic therapy for postcesarean endomyometritis.

Puerperal uterine infection, or endomyometritis, occurs more commonly after cesarean section than after vaginal birth. With the rate of cesarean delivery almost 25% of all births in this country, such infection is relatively common. The classic therapy for postcesarean endomyometritis is the combination of clindamycin and an aminoglycoside, usually gentamicin or tobramycin. This regimen has requisite antimicrobial activity against the aerobes and anaerobes of the cervicovaginal flora that usually cause this illness. In the last decade, however, the availability of broad-spectrum beta-lactam antibiotics has enabled the clinician to combat postcesarean infection with single-agent antimicrobial chemotherapy, or monotherapy. "Higher-generation" cephalosporins such as cefoxitin, cefotetan, and moxalactam, as well as the semisynthetic penicillins ticarcillin, piperacillin, and mezlocillin, have all been used alone in the therapy for postpartum infection. The addition of a beta-lactamase inhibitor to this class of drugs now offers a further resource to the practitioner if beta-lactamase-mediated antibiotic resistance arises in the patient population being treated.

Role of newer antimicrobial agents in the treatment of mixed aerobic and anaerobic infections.

Mixed infections with aerobic and anaerobic bacteria are being recognized with increasing frequency in clinical practice. Several concepts regarding such infections are clinically significant for the physician. These include the presence and significance of species in the Bacteroides fragilis group at clinical sites of infection, the facilitation of B. fragilis virulence by beta-lactamase producing aerobic bacteria and the role of enterococci in such infections. In response to the need for new forms of therapy for mixed aerobic and anaerobic infections, several new classes of antimicrobial agents have been introduced. Some of these allow for the potential option of monotherapy in certain clinical settings. In addition to clinical and microbiologic efficacy, safety and cost-effectiveness are factors that must be addressed with regard to these agents.