Mycobacterium arupense in Cancer Patients: An Emerging Infection or a Commensal Organism.

Mycobacterium arupense is a slow-growing, nonchromogenic, acid-fast bacillus. Its clinical spectrum, epidemiology, and frequency of colonization versus true infection remain unknown. We evaluated the clinical significance of M arupense and positive cultures from cancer patients.We retrospectively reviewed records of all cancer patients treated at our institution between 2007 and 2014 to identify those who had positive cultures for M arupense. Mycobacterium arupense was identified by sequencing the 16S rRNA and hsp65 genes. A total of 53 patients had positive cultures, 100% of which were isolated from respiratory specimens. Of these, 7 patients met the American Thoracic Society/Infectious Diseases Society of America criteria for a definitive diagnosis of M arupense infection, 14 cases were considered to be probable infections, and 29 cases were considered to be possible infections. Of the included patients, 13 received therapy for M arupense infection and 40 did not.The outcomes of treated and untreated patients did not differ significantly. No relapses of M arupense infection. In addition, there were no M arupense-related deaths in either group.In cancer patients, M arupense appears to be mostly a commensal organism rather than a pathogen. Patients who did or did not receive treatment had similar outcomes. Validation of these findings in a larger prospective trial is warranted.

Prevention of transmission of multidrug-resistant organisms during catheter exchange using antimicrobial catheters.

Exchanging a central venous catheter (CVC) over a guide wire for a fresh uncoated CVC in the presence of bacteremia can result in cross-infection of the newly exchanged CVC. A recent retrospective clinical study showed that exchanging a catheter over a guide wire in the presence of bacteremia using an antimicrobial minocycline-rifampin (M/R) catheter may improve outcomes. To expand on this, we developed an in vitro cross-contamination model of exchange to evaluate the efficacy of different antimicrobial CVCs in preventing cross-contamination of multidrug-resistant organisms during exchange. Uncoated CVCs were allowed to form biofilm by methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. After 24 h, the biofilm-colonized CVCs were placed in a glass tube containing bovine calf serum plus Mueller-Hinton broth, and each catheter was exchanged over a guide wire for a fresh uncoated or an M/R-, chlorhexidine-silver sulfadiazine (CHX/SS)-, or chlorhexidine-M/R (CHX-M/R)-coated CVC. Cross-contamination of exchanged catheters was enumerated by sonication and quantitative plating methods. The exchange of M/R CVCs completely prevented cross-contamination by MRSA biofilms compared to control exchanged CVCs (P<0.0001). Exchange with CHX/SS CVCs reduced but did not completely prevent cross-contamination by MRSA (P=0.005). Exchange with CHX-M/R CVCs completely prevented cross-contamination by MRSA, P. aeruginosa, and C. albicans biofilms (P<0.0001). Furthermore, CHX-M/R CVCs were superior to M/R CVCs against P. aeruginosa and C. albicans (P=0.003) and were superior to CHX/SS CVCs against MRSA and P. aeruginosa (P=0.01). In conclusion, exchange with the novel CHX-M/R CVC was the only exchange effective in completely and concurrently preventing cross-contamination from bacteria and Candida.

Central venous catheter-associated Nocardia bacteremia in cancer patients.

Central venous catheters, often needed by cancer patients, can be the source of Nocardia bacteremia. We evaluated the clinical characteristics and outcomes of 17 cancer patients with Nocardia bacteremia. For 10 patients, the bacteremia was associated with the catheter; for the other 7, it was a disseminated infection. N. nova complex was the leading cause of bacteremia. Nocardia promoted heavy biofilm formation on the surface of central venous catheter segments tested in an in vitro biofilm model. Trimethoprim- and minocycline-based lock solutions had potent in vitro activity against biofilm growth. Patients with Nocardia central venous catheter-associated bloodstream infections responded well to catheter removal and antimicrobial drug therapy, whereas those with disseminated bacteremia had poor prognoses.

Clinical effectiveness and risk of emerging resistance associated with prolonged use of antibiotic-impregnated catheters: more than 0.5 million catheter days and 7 years of clinical experience.

OBJECTIVES: Catheters coated with minocycline and rifampin are proven to decrease the rates of central line-associated bloodstream infection; however, it is unclear whether success occurs independent of other infection control precautions. We evaluated the effect of catheters coated with minocycline and rifampin with and without other infection control precautions on our rates of central line-associated bloodstream infection in critically ill patients and on antibiotic resistance throughout the hospital and in the intensive care unit. DESIGN: Retrospective clinical cohort study conducted during 1999-2006 with an observational laboratory component. SETTING: A tertiary university-based cancer center. PATIENTS: All 8009 patients admitted to the medical intensive care unit were subjects for the surveillance of central line-associated bloodstream infection. All Staphylococcus aureus and coagulase-negative staphylococci clinical isolates cultured at our institution during the same period were subjects for laboratory testing. INTERVENTIONS: Using catheters coated with minocycline and rifampin and implementing infection control precautions. MEASUREMENTS AND MAIN RESULTS: Incidence of central line-associated bloodstream infection in the medical intensive care unit. Change in resistance to tetracycline and rifampin in clinically relevant staphylococcal isolates in the intensive care unit and hospitalwide. During the study period, 9200 catheters coated with minocycline and rifampin were used hospitalwide over a total of 511,520 catheter days. The incidence of central line-associated bloodstream infection per 1000 patient days in the medical intensive care unit significantly and gradually decreased from 8.3 in 1998 to 1.2 in 2006 (p ≤ .001). The resistance of S. aureus and coagulase negative staphylococci clinical isolates to tetracycline or rifampin in the intensive care unit and on a hospitalwide level remained stable or decreased significantly during the same period. CONCLUSIONS: Catheters coated with minocycline and rifampin significantly decreased the incidence of central line-associated bloodstream infection in the medical intensive care unit in a manner that was independent and complementary to the infection control precautions. Although this study strongly suggests an association between catheters coated with minocycline and rifampin use and a decrease in central line-associated bloodstream infection, because of multiple other concurrent interventions, the results should be interpreted cautiously until a prospective study is conducted. Furthermore, long-term use of these devices is not associated with increased resistance of staphylococcal isolates to tetracycline and rifampin in the intensive care unit or throughout the hospital.