A Case Series of Nontuberculous Mycobacterial Blood Stream Infections Among Non-cancer Patients

Abstract

Background. Nontuberculous mycobacteria (NTM) are ubiquitous environmental organisms associated with a variety of infections. NTM blood stream infections (BSI) have been increasingly reported among hematology-oncology patients with central venous catheters, however, not among other patient populations. The optimal antimicrobial agents and duration of therapy for NTM BSI are unknown. Methods. Retrospective medical record review was conducted to characterize those who had blood cultures positive for NTM from July 2012 to March 2015 at Lemuel Shattuck Hospital (LSH). Demographics, laboratory, microbiology and clinical data were collected. NTM BSI were identified by the reports from the microbiology laboratory at LSH where NTM were recognized as beaded Gram-positive rods on Gram stain (figure) using the samples from conventional blood culture bottles. Colony growth was observed on blood agar and/or chocolate agar. Colonies were sent to the Massachusetts State Laboratory for identification and confirmed as NTM. Results. Twenty-three NTM BSI cases among 21 patients were identified. Median age [interquartile range (IQR)] was 31 [16] years and 12 patients (57%) were male. All cases had peripherally inserted central catheters (PICC) to receive long-term antibiotics for primary infections at the time of, or several days prior to, NTM BSI. Nineteen patients (90%) had history of intravenous drug use. Fever >38°C was common (n = 17, 81%). Leukocytosis was uncommon (n = 4, 19%). The most common species was Mycobacterium fortuitum (n = 11, 48%) followed by Mycobacterium abscessus (n = 4, 19%). Median time to blood culture positivity [IQR] was 5 [1.5] days. All the PICCs were removed and 7 cases (30%) received antibiotic treatment specific for NTM BSI. Median follow-up period [IQR] was 45 [254] days and all the patients were asymptomatic at the end of the follow-up. Conclusion. To our knowledge, this is the first case series of NTM BSI among non-cancer patients. Most patients were cured by PICC removal alone. NTM BSI may be underdiagnosed as NTM can take longer than the routine blood culture incubation period to grow and Gram-positive bacilli can be treated as contaminants. Awareness of NTM BSI is essential to accumulate cases and establish an optimal treat-ment strategy. (Figure Presented) .