Relapse versus Reinfection of Mycobacterium avium Complex Pulmonary Disease. Patient Characteristics and Macrolide Susceptibility.

RATIONALE: Clinical recurrence of Mycobacterium avium complex (MAC) pulmonary disease occurs in 10 to 40% of patients treated for this disease process. Episodes of clinical recurrence may represent true relapse from the same MAC strain or reinfection with a new strain. OBJECTIVES: The purpose of this study was to investigate the clinical implications of separating patients into these two groups. METHODS: This retrospective study evaluated patients with a clinical recurrence of MAC pulmonary disease at our institution from 2000 to 2012. Isolates were genotyped using pulsed-field gel electrophoresis to differentiate relapse versus reinfection. Change in macrolide susceptibility was also analyzed. MEASUREMENTS AND MAIN RESULTS: In our cohort, 25% of patients suffered a clinical recurrence. Of the 46 included patients, 25 (54%) suffered a true relapse and 21 (46%) had a reinfection. Median time between completion of therapy and clinical recurrence was significantly lower in the relapse group compared with the reinfection group (210 d vs. 671 d; P = 0.004). The measured convalescent macrolide minimum inhibitory concentrations were significantly more likely to increase in the relapse group compared with the reinfection group (80 vs. 33%; P = 0.002). No differences in clinical outcomes were observed between the two groups at conclusion of the study. CONCLUSIONS: Our findings suggest that patients with true relapse of MAC pulmonary disease present earlier than those with reinfection. Routine use of pulsed-field gel electrophoresis in the management of clinical recurrences may be beneficial, as those suffering a relapse are more likely to have increasing macrolide minimum inhibitory concentrations than those with reinfection.

Epidemiology and Management of Emerging Drug-Resistant Gram-Negative Bacteria: Extended-Spectrum ß-Lactamases and Beyond.

Worldwide prevalence of antimicrobial resistance is rapidly increasing, primarily a result of antibiotic misuse in the medical community. Resistant infections involving the urinary tract are typically caused by gram-negative bacteria. When treating these infections, clinicians have few effective antimicrobials to choose from and many are associated with significant adverse effects. There are now situations when clinicians are tasked with managing infections from pan-resistant organisms; thus, it is of paramount importance that spread of resistance be controlled. This review discusses common gram-negative resistance classes, highlighting the mechanisms of resistance, risk factors, type of infections, treatment, and outcomes associated with each class.

Comparison of Clinical Features, Virulence, and Relapse among Mycobacterium avium Complex Species.

RATIONALE: Traditionally, Mycobacterium avium complex (MAC) has been composed of M. avium and M. intracellulare; however, advances in genetic sequencing have allowed discovery of several novel species. With these discoveries, investigation of differences in risk factors, virulence, and clinical outcomes have emerged. OBJECTIVES: We conducted a retrospective cohort study evaluating all MAC isolates obtained from pulmonary specimens at our institution from 2000 to 2012 and investigated the clinical courses associated with distinct MAC species. METHODS: To classify isolates into distinct species, a multilocus sequence analysis using rpoB and internal transcribed spacer (ITS) as targets was performed. We reviewed patient medical records to analyze clinical characteristics and outcomes for the cohort. MEASUREMENTS AND MAIN RESULTS: Of the isolates from the 448 included patients, 54% were M. avium, 18% were M. intracellulare, and 28% were M. chimaera. Using American Thoracic Society/Infectious Diseases Society of America criteria, patients whose isolates were identified as M. avium (adjusted odds ratio [AOR], 2.14; 95% confidence interval [CI], 1.33-3.44) or M. intracellulare (AOR, 3.12; 95% CI, 1.62-5.99) were more likely to meet criteria for infection than patients with M. chimaera. Patients infected with M. chimaera were more likely to be prescribed an immunosuppressant compared with all other patients (AOR, 2.75; 95% CI, 1.17-6.40). Patients treated for infections with M. avium (AOR, 5.64; 95% CI, 1.51-21.10) and M. chimaera (AOR, 4.47; 95% CI, 1.08-18.53) were more likely to have a clinical relapse/reinfection than those with M. intracellulare. CONCLUSIONS: Our findings suggest that specific MAC species have varying degrees of virulence and classifying MAC isolates into distinct species aids in identifying which patients are at higher risk of clinical relapse/reinfection.

Evaluation of Vitek MS for rapid classification of clinical isolates belonging to Mycobacterium avium complex.

We evaluated the ability of the Vitek MS system to classify clinical pulmonary Mycobacterium avium complex isolates compared to multilocus sequence analysis. Vitek MS accurately identified 55% of the isolates as M. avium and 18% as M. intracellulare, but misidentified 24 (27%) Mycobacterium chimaera isolates as Mycobacterium intracellulare.

Adult immunization and its impact on children.

The prevention of illness through vaccination is one of the most essential services pediatricians provide to their patients. However, the importance of adult vaccination and its impact on the health of children are often overlooked. There remains a large portion of adults in the United States who are not compliant with the Advisory Committee on Immunization Practices immunization schedule. These people provide a potential reservoir for the spread of vaccine-preventable illness to children and adolescents. There are numerous contributing factors to the lack of immunization. Pediatricians, along with adult health care providers, can serve an important role by educating parents, guardians, and adult contacts of children on the importance of receiving the recommended adult vaccinations and the role of vaccines in preventing the spread of disease to the pediatric population.