Disseminated Mycobacterium chelonae infection resulting in endocarditis

Disseminated Mycobacterium chelonae infection causing pacemaker lead endocarditis in an immunocompetent host

Pacemaker infection with Mycobacterium chelonae has not been reported previously. We report the first case of pacemaker lead endocarditis due to M. chelonae, which was successfully treated with multidrug regimen. M. chelonae is regarded as an environmental bacterium and its pathogenicity has been recognised recently. The present case illustrates its ability as a primary invader should not be underestimated, especially in an immunocompetent patient with indwelling devices. Epidemiology and management of this rare cause of culture-negative endocarditis is discussed.

Native-valve endocarditis caused by Mycobacterium chelonae, misidentified as polymicrobial gram-positive bacillus infection

Mycobacterium chelonae, a species of rapidly growing mycobacteria, may grow in routine blood culture media and stain as gram-positive bacilli, which may cause diagnostic confusion. A patient with native-valve endocarditis caused by M. chelonae, which was misidentified as various gram-positive bacilli, is presented.

Mycobacterium abscessus endocarditis: a case report and literature review

Infective endocarditis owing to Mycobacterium abscessus infection is rarely reported. Most cases of infective endocarditis caused by Mycobacterium abscessus are seen in patients after valve replacement. Although early surgical intervention is recommended and medical treatment with antibiotics according to the susceptibility to the pathogen, such as amikacin, imipenem, cefoxitin, quinolones and macrolides, are applied, the course of such endocarditis is usually subacute and often has fatal outcomes. The present case was a 29-year-old male patient who was an intravenous drug user who had recurrent endocarditis caused by Mycobacterium abscessus. Unusually, our reported case was infected on his native valve. However, we experienced recurrence despite antimicrobial therapy. For culture-negative endocarditis, physicians should consider the possibility of Mycobacterium abscessus infection and related treatment difficulties.

Diagnostic methods. Current best practices and guidelines for identification of difficult-to-culture pathogens in infective endocarditis

IE is a serious, life-threatening disease. Because treatment must often be adapted to the pathogen involved, rapid identification of the etiologic agent is critical to successful management of each patient. When difficult-to-culture pathogens are involved, routine microbiologic tests, including blood culture, may remain negative. Because such cases may account for up to 31% of all IE cases, alternative diagnostic approaches are necessary. Among the etiologic agents of culture-negative endocarditis, C burnetii and Bartonella spp play a major role; each is responsible for up to 3% of episodes of IE. The authors therefore recommend the systematic use of specific serologies in all cases of clinically suspected endocarditis. The cross-reactivity between C burnetii, Bartonella spp, and Chlamydia spp is of diagnostic importance because all are potential etiologic agents of endocarditis. However, given that the levels of specific antibodies observed in Bartonella endocarditis are extremely high, low-level cross-reactions with other antigens should not lead to misdiagnosis, provided serology for all suspected agents is performed. When serologic test results are negative for both Bartonella spp and C burnetii, special staining by the Gram, Giemsa, Gimenez, PAS, Warthin-Starry, and Grocott methods may guide the use of new diagnostic tools such as PCR and tissue culture for isolation and identification of the causative agent. Such novel approaches may lead to more comprehensive patient evaluations and the discovery of new etiologic agents of IE.

Diagnostic methods current best practices and guidelines for identification of difficult-to-culture pathogens in infective endocarditis

Culture-negative endocarditis currently represents a diagnostic challenge for physicians. Traditional methods such as histology, serology, and culture have been improved and new molecular techniques have been developed to improve the detection of difficult-to-culture agents. Serologic tests for the two most frequent etiologic agents, Coxiella burnetii and Bartonella spp, should be performed first because they can usually be identified easily in this way. The sensitivity of culture for intracellular bacteria has been improved by inoculation of samples in shell vials and by the use of novel tissue cell lines. Recently, universal and species-specific primers have been designated to amplify bacterial DNA directly from resected valves, allowing positive identification.

Mycobacterium fortuitum complex endocarditis-case report and literature review

Endocarditis due to Mycobacterium fortuitum complex is a rare entity generally linked to the hospital environment. Only 18 cases have been published since 1966. Here we present a case of a female who developed an endocarditis due to Mycobacterium chelonae after valve replacement as well as a review of the literature. The course of this kind of endocarditis is generally subacute and the outcome is usually fatal. Blood cultures were positive in 75% of cases of metallic valve endocarditis, versus 20% in bioprostheses. The treatment must include antibiotics that have shown activity against these mycobacteria, such as amikacin, imipenem, cefoxitin, fluorinated quinolones and macrolides (especially clarithromycin). Surgical removal is recommended. Although the prognosis for the patient is poor, we should expect better outcomes with the use of new antibiotic regimens.

Emergence of resistance to clarithromycin during treatment of disseminated cutaneous Mycobacterium chelonae infection: case report and literature review

Results of in vitro susceptibility studies and one clinical trial have led to recommendations of clarithromycin monotherapy for the treatment of disseminated cutaneous Mycobacterium chelonae infections. We describe the case of a 65-year-old woman, immunocompromised by the use of chronic steroid therapy, who developed disseminated cutaneous infection with M. chelonae and failed clarithromycin monotherapy due to the development of drug resistance. In the relapse isolate we document the presence of a single point mutation at position 2058 in the gene coding for 23S rRNA peptidyltransferase regions, a mutation previously implicated in the development of resistance to clarithromycin. Two susceptible control isolates lacked the mutation. Three additional reports in the literature of patients developing recurrent skin lesions with clarithromycin-resistant M. chelonae following initial response to monotherapy are summarized. We demonstrate that clarithromycin monotherapy in patients with disseminated cutaneous infections can lead to clarithromycin resistance and therapeutic failure associated with a single point mutation at position 2058 of 23S rRNA.

Endocarditis due to rare and fastidious bacteria

The etiologic diagnosis of infective endocarditis is easily made in the presence of continuous bacteremia with gram-positive cocci. However, the blood culture may contain a bacterium rarely associated with endocarditis, such as Lactobacillus spp., Klebsiella spp., or nontoxigenic Corynebacterium, Salmonella, Gemella, Campylobacter, Aeromonas, Yersinia, Nocardia, Pasteurella, Listeria, or Erysipelothrix spp., that requires further investigation to establish the relationship with endocarditis, or the blood culture may be uninformative despite a supportive clinical evaluation. In the latter case, the etiologic agents are either fastidious extracellular or intracellular bacteria. Fastidious extracellular bacteria such as Abiotrophia, HACEK group bacteria, Clostridium, Brucella, Legionella, Mycobacterium, and Bartonella spp. need supplemented media, prolonged incubation time, and special culture conditions. Intracellular bacteria such as Coxiella burnetii cannot be isolated routinely. The two most prevalent etiologic agents of culture-negative endocarditis are C. burnetti and Bartonella spp. Their diagnosis is usually carried out serologically. A systemic pathologic examination of excised heart valves including periodic acid-Schiff (PAS) staining and molecular methods has allowed the identification of Whipple's bacillus endocarditis. Pathologic examination of the valve using special staining, such as Warthin-Starry, Gimenez, and PAS, and broad-spectrum PCR should be performed systematically when no etiologic diagnosis is evident through routine laboratory evaluation.

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.

Recurrent catheter-related infection caused by a single clone of Mycobacterium chelonae with two colonial morphotypes

We describe herein a recurrent catheter-related (Port-A-Cath; Smiths Industries Medical Systems [SIMS] Deltec, Inc., St. Paul, Minn.) infection caused by multidrug-resistant Mycobacterium chelonae with two colonial morphotypes in a 53-year-old woman with gastric adenocarcinoma. Four isolates recovered from this patient within a 3-month period were found to belong to a single clone on the basis of the isolates' identical antibiotypes as determined by the E test and their identical random amplified polymorphic DNA patterns.