Mycobacterium Septicum Research Articles

1631. Mycobacterium septicum: A 6-year Clinical Experience from a Tertiary Hospital and Reference Laboratory

Background Mycobacterium septicum is a rapidly growing non-tuberculous mycobacterium. It is a ubiquitous organism capable of causing infections in both healthy and immunocompromised individuals. Only a few cases have been reported to date, and standard therapeutic regimens, and optimal treatment duration have not been defined.MethodsWe conducted a retrospective chart review of all patients seen at Mayo Clinic in Rochester, MN from July 2014 to March 2020 from whom Mycobacterium septicum was isolated in culture by our clinical microbiology laboratory.ResultsThere were 12 patients identified with M. septicum infection – 7 males and 5 females. The average age was 67 years, with an age range of 48 to 80 years. Seven of 12 isolates obtained were from sputum samples. Only one patient was on immunosuppressive medication. Three cases were considered clinically significant infections for which directed anti-mycobacterial therapy was instituted. In two of these three cases, co-infection with Mycobacterium avium complex (MAC) was seen. Underlying structural lung disease was present in the two cases of pulmonary infections. Peritoneal dialysis catheter-related peritonitis was seen in the third case. All the isolates were susceptible to amikacin, ciprofloxacin, imipenem, linezolid, moxifloxacin, and trimethoprim-sulfamethoxazole (TMP-SMX). The isolates were resistant to clarithromycin and doxycycline.Patient Characteristics, Associated M. septicum Illness, and Therapy Provided Antimicrobial Susceptibility Profiles of the Mycobacterium septicum Isolates, MIC (mcg/mL) and Interpretation Patient Demographics and Specimen Source of Mycobacerium septicum Isolates ConclusionM. septicum is an unusual cause of non-tuberculous mycobacterial infection. The presence of a foreign body may increase the risk of infection. Individuals with underlying structural lung disease are also likely to be at increased risk of developing pulmonary infection. Generalized treatment recommendations are limited by the lack of prospective controlled trials; hence, optimal antibiotic regimen and treatment duration have not been firmly established. Susceptibility testing should be performed to guide treatment selection, but the use of combination therapy with potentially empiric agents like amikacin, ciprofloxacin, imipenem, linezolid, moxifloxacin, and TMP-SMX as demonstrated in this small study, can be considered. A high rate of macrolide resistance was noted in our study.Disclosures All Authors: No reported disclosures

Mycobacterium septicum: a 6-Year Clinical Experience from a Tertiary Hospital and Reference Laboratory.

Mycobacterium septicum is a rarely identified nontuberculous mycobacterium capable of causing infections in both healthy and immunocompromised individuals. Only a few cases of M. septicum infections have been reported, which makes recognizing corresponding clinical disease more challenging for clinicians. Antimicrobial susceptibility profiles for this organism are not well described, and corresponding optimal therapeutic regimens have not been established. We report a tertiary care center's experience with M. septicum from 2014 to 2020. Twelve adult patients with positive cultures for M. septicum were identified. Most cases were identified from sputum samples of individuals with underlying lung disease. Most cases involving M. septicum isolation in culture were not felt to be clinically significant. Two cases were considered possible infections, while only one case was considered a definite infection that required antimicrobial treatment. All M. septicum isolates were susceptible in vitro to amikacin, ciprofloxacin, imipenem, linezolid, moxifloxacin, and trimethoprim-sulfamethoxazole. Isolates were universally resistant to clarithromycin and doxycycline. The isolation of M. septicum in culture is uncommon and requires clinical correlation to determine its clinical relevance and need for treatment. Susceptibility testing should be performed to guide therapy.

Non-tuberculous Mycobacterium species causing mycobacteriosis in farmed aquatic animals of South Africa

BackgroundMycobacteriosis caused by non-tuberculous mycobacteria (NTM), is among the most chronic diseases of aquatic animals. In addition, fish mycobacteriosis has substantial economic consequences especially in the aquaculture and fisheries industry as infections may significantly decrease production and trade. Some fish NTM pathogens are highly virulent and zoonotic; as such, infection of aquaria with these pathogens is a public health concern.In this study, we report isolation of nine different NTM species from sixteen aquatic animals including different fish species, frogs and a crocodile. Given the clinical significance of Mycobacterium marinum and its close relation to Mycobacterium tuberculosis, as well as the significance of ESAT 6 and CFP-10 secretion in mycobacterial virulence, we analysed the esxA and esxB nucleotide sequences of M. marinum isolates identified in this study as well as other mycobacteria in the public databases.ResultsMycobacterium shimoidei, Mycobacterium marinum, Mycobacterium chelonae, Mycobacterium septicum /M. peregrinum and Mycobacterium porcinum were isolated from gold fish, Guppy, exotic fish species in South Africa, koi and undefined fish, Knysna seahorse, as well Natal ghost frogs respectively, presenting tuberculosis like granuloma. Other NTM species were isolated from the studied aquatic animals without any visible lesions, and these include Mycobacterium sp. N845 T, Mycobacterium fortuitum, a member of the Mycobacterium avium complex, and Mycobacterium szulgai. Phylogenetic analysis of mycobacteria, based on esxA and esxB genes, separated slow growing from rapidly growing mycobacteria as well as pathogenic from non-pathogenic mycobacteria in some cases.ConclusionsIsolation of the different NTM species from samples presenting granuloma suggests the significance of these NTM species in causing mycobacteriosis in these aquatic animals. The study also revealed the potential of esxA and esxB sequences as markers for phylogenetic classification of mycobacteria. Observations regarding use of esxA and esxB sequences for prediction of potential pathogenicity of mycobacteria warrants further investigation of these two genes in a study employing NTM species with well-defined pathogenicity.

Mycobacterium lutetiense sp. nov., Mycobacterium montmartrense sp. nov. and Mycobacterium arcueilense sp. nov., members of a novel group of non-pigmented rapidly growing mycobacteria recovered from a water distribution system.

From our recent survey of non-pigmented rapidly growing mycobacteria in the Parisian water system, three groups of isolates (taxons 1-3) corresponding to possible novel species were selected for taxonomic study. The three taxa each formed creamy white, rough colonies, had an optimal growth temperature of 30 °C, hydrolyzed Tween 80, were catalase-positive at 22 °C and expressed arylsulfatase activity. All three were susceptible to amikacin, ciprofloxacin and tigecycline. The three taxa produced specific sets of mycolic acids, including one family that has never previously been described, as determined by thin layer chromatography and nuclear magnetic resonance. The partial rpoB sequences (723 bp) showed 4-6 % divergence from each other and more than 5 % differences from the most similar species. Partial 16S rRNA gene sequences showed 99 % identity within each species. The most similar sequences for 16S rRNA genes (98-99 % identity over 1444-1461 bp) were found in the Mycobacterium fortuitum group, Mycobacterium septicum and Mycobacterium farcinogenes. The three taxa formed a new clade (bootstrap value, 99 %) on trees reconstructed from concatenated partial 16S rRNA, hsp65 and rpoB sequences. The above results led us to propose three novel species for the three groups of isolates, namely Mycobacterium lutetiense sp. nov. [type strain 071T=ParisRGMnew_1T (CIP 110656T=DSM 46713T)], Mycobacterium montmartrense sp. nov. [type strain 196T=ParisRGMnew_2T (CIP 110655T=DSM 46714T)] and Mycobacteriu marcueilense sp. nov. [type strain of 269T=ParisRGMnew_3T (CIP 110654T=DSM 46715T)].

The first case of pulmonary disease caused by Mycobacterium septicum in China

Mycobacterium septicum is a rapidly growing Mycobacterium (RGM) that rarely causes pulmonary disease globally. We describe a case of M. septicum pulmonary disease, which to our knowledge is the first reported in China. The isolates were identified as M. septicum and were susceptible in vitro to amikacin, ciprofloxacin, ofloxacin, levofloxacin, kanamycin, and sulfamethoxazole.

A First Case of Non-tuberculous Mycobacterial Disease Caused by <i>Mycobacterium Septicum</i> Accompanied with Tuberculous Subcutaneous Abscess.

A First Case of Non-tuberculous Mycobacterial Disease Caused by <i>Mycobacterium Septicum</i> Accompanied with Tuberculous Subcutaneous Abscess.

Catheter-related bloodstream infections caused by rapidly growing nontuberculous mycobacteria: a case series including rare species

Rapidly growing nontuberculous mycobacteria (RGMs) are responsible for a variety of clinical syndromes in humans including catheter-related blood stream infections (CRBSIs). Recently, we identified a cluster of RGM-associated CRBSI at our institution. We describe the epidemiologic and clinical patterns associated with these infections. We conducted a retrospective single-center review of RGM CRBSI between May 2004 and June 2005. RGMs isolated from blood cultures of 6 patients included Mycobacterium mucogenicum (2), Mycobacterium fortuitum (2), and the rare RGM species, Mycobacterium neoaurum (1) and Mycobacterium septicum (1). All of the patients had a long-term intravascular catheter (mean duration, 6.5 months). Bacteremia was resolved in all patients after catheter removal and appropriate antibiotics. None of the patients suffered a relapse of RGM CRBSI, and all survived to 1 year. RGMs are causative pathogens in both immunosuppressed and immunocompetent individuals with long-term intravascular catheters and blood stream infections. Recent trends at our center suggest that infections with these pathogens are rising.

Isolation of Mycobacterium septicum from the sputum of a patient suffering from hemoptoic pneumonia

A rapidly growing mycobacterium was isolated in pure culture from the sputum of a 78-year-old woman suffering from hemoptoic pneumonia. The isolate exhibited an antimicrobial susceptibility pattern and a biochemical profile similar to that of Mycobacterium septicum ATCC 700731 T and shared 100% 16S rRNA gene sequence similarity with this type strain over 1480 bp. Its partial rpoB sequence shared 98.2% similarity with the latter species, suggesting the isolate was representative of a sequevar of M. septicum. Contrary to the type strain, this isolate was resistant to azithromycin, erythromycin, vancomycin and tobramycin. This case illustrates the first isolation from sputum of M. septicum, a member of the Mycobacterium fortuitum group previously isolated once from bacteremia. Strain D13 has been deposited in the Collection de l'Institut Pasteur as CIP 108512.

Mycobacterium septicum sp. nov., a new rapidly growing species associated with catheter-related bacteraemia.

Rapidly growing mycobacteria are capable of causing several clinical diseases in both immunosuppressed and immunocompetent individuals. A previously unidentified, rapidly growing mycobacterium was determined to be the causative agent of central line sepsis in a child with underlying metastatic hepatoblastoma. Four isolates of this mycobacterium, three from blood and one from the central venous catheter tip, were studied. Phenotypic characterization, HPLC and genetic analysis revealed that while this organism most closely resembled members of the Mycobacterium fortuitum complex and Mycobacterium senegalense, it differed from all previously described species. Phenotypic tests useful in differentiating this species from similar rapidly growing mycobacteria included: growth at 42 degrees C, hydrolysis of acetamide, utilization of citrate, production of arylsulfatase (3-d), acidification of D-mannitol and i-myo-inositol, and susceptibility to erythromycin, vancomycin and tobramycin. The name Mycobacterium septicum is proposed for this new species. The type strain has been deposited in Deutsche Sammlung von Mikroorganismen und Zellkulturen as DSM 44393T and in the American Type Culture Collection as strain ATCC 700731T.