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The finding of unexpected hypogammaglobulinemia and concomitant infectious complications in six heart transplant recipients highlights a possible complication in a subset of patients receiving newer immunosuppressive agents. A larger prospective study is underway to determine risk factors for development of post-transplant hypogammaglobulinemia and to assess pre-transplant immune status of these recipients. Monitoring of immunoglobulin levels in high-risk patients receiving intensified immunosuppressive therapy for rejection may help to prevent infectious complications.

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We implemented the QuantiFERON-TB Gold (QFT-G) In-Tube test to identify latent tuberculosis infection among potential employees prior to employment. The rates of indeterminate QFT-G In-Tube test results were higher than expected and prompted an investigation that led to successful interventions (eg, manual vortexing before incubation and the use of a modified in-tube method). The tracking of indeterminate results is suggested as an important quality control measure.

SUMMARY Objectives Limited clinical experience exists regarding the management of prosthetic joint infection (PJI) due to multidrug-resistant (MDR) Gram-negative organisms. We review three cases of carbapenem-resistant Klebsiella pneumoniae (CRKP) complicating PJI. Methods This was a retrospective study of all patients at a tertiary care institution with CRKP complicating PJI between January 2007 and December 2010. Demographic data, procedures, organisms involved, length of stay, antibiotic treatments, and outcomes were collected. Antimicrobial susceptibility testing was performed on CRKP isolates, and the mechanism of resistance was ascertained by PCR. Results This analysis demonstrated that: (1) the CRKP possessed blaKPC and were difficult to eradicate (persistent) in PJI; (2) multiple surgeries and antibiotic courses were undertaken and patients required a prolonged length of stay; (3) resistance to colistin and amikacin emerged on therapy; (4) the same strain of CRKP may be responsible for relapse of infection; (5) significant morbidity and mortality resulted. Conclusions These cases highlight the opportunistic and chronic nature of CRKP in PJIs and the need for aggressive medical and surgical treatment. Further investigations of the management of CRKP PJI and new drug therapies for infections due to MDR Gram-negative organisms are urgently needed.

We reviewed the clinical, radiographic, and histologic features of nine patients with AIDS and pulmonary disease due to Mycobacterium avium complex (MAC). Pulmonary MAC disease was defined by (1) the isolation of MAC from two or more lower respiratory tract specimens or from a single lung biopsy sample, (2) an infiltrate revealed by chest radiography, and (3) the absence of other identified pulmonary pathogens or malignancies. Pulmonary MAC disease was present in five (2.5%) of 200 patients with disseminated MAC infection and in four additional patients without evidence of dissemination, as assessed by blood culture. The median CD4 cell count at the time of presentation was 90/microL. Pulmonary MAC disease was the initial AIDS-defining infection in five patients and presented within a median of 5 months after the initial infection in four patients. Radiographic patterns for these nine patients included consolidating or nodular infiltrates and cavitation. The histopathology of pulmonary MAC disease was characterized by granulomatous inflammation, often associated with necrosis and few evident organisms. The conditions of all patients treated with multidrug regimens clinically improved.

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To investigate the possible embryologic relation between small-cell carcinoma of the lung and medullary thyroid carcinoma, we measured plasma histaminase (an enzyme found in medullary carcinoma tissue) in 25 patients with small-cell tumors. The assays used histamine and putrescine as substrates. Thirty-two per cent of the patients by the histamine assay, and 31 per cent by the putrescine, had values greater than +2 S.D. from the mean for 63 normal persons. In contrast, among 20 patients with squamous and large-cell lung tumors, one (by the histamine assay), and two (by the putrescine) had elevated values. In four of five autopsy cases, histaminase was high in small-cell carcinoma tissue. The enzyme in plasma and in tumor behaved as classic histaminase in substrate specificity, and in response to inhibitors. The data support the proposed embryologic relation between small-cell lung carcinoma and medullary thyroid carcinoma, and further associate histaminase with some neural crest tumors.