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  • Case report
  • Open Access
  • Open Peer Review

Mycobacterium mucogenicum bacteremia: major role of clinical microbiologists

BMC Infectious Diseases201818:646

https://doi.org/10.1186/s12879-018-3545-3

  • Received: 4 August 2018
  • Accepted: 23 November 2018
  • Published:
Open Peer Review reports

Abstract

Introduction

Mycobacterium mucogenicum is a rare but emerging cause of infections, especially in immunocompromised patients.

Case presentation

We describe a new case of M. mucogenicum catheter-related bloodstream infection in a 34-year-old woman with ovarian cancer. M. mucogenicum was at first considered as a contaminant, and susceptibility testing was not performed. Usual susceptibility of M. mucogenicum motivated prescription of clarithromycin and moxifloxacin. Finally, our isolate was confirmed susceptible to both drugs. Clinical outcome was favorable with no relapse of infection after antibiotics discontinuation despite concomitant chemotherapy.

Conclusion

Our case illustrates the need for a clinician-microbiologist dialogue in case of suspected M. mucogenicum infection to avoid delaying appropriate management.

Keywords

  • Mycobacterium mucogenicum
  • Rapidly growing mycobacteria
  • Bacteremia
  • Catheter-related infection

Background

Non-tuberculous mycobacteria are an important cause of human infections. Among them, rapidly growing mycobacteria are defined by their ability to produce mature colonies on agar plates within 7 days. They are rare but recently increasing causes of infections, especially in immunocompromised patients [1]. One of the most common form of disease is catheter-related bloodstream infection [2]. The pathogen most frequently implicated in case of catheter-related bloodstream is Mycobacterium mucogenicum [3]. Because rapidly growing mycobacteria are ubiquitous environmental microorganisms, their isolation requires a careful assessment of their clinical significance. We report a new case of M. mucogenicum bacteremia and discuss the role of microbiologists and its clinical management.

Case presentation

A 34-year-old woman with platin-resistant metastatic ovarian cancer experimented fever and chills during intravenous infusion of the anti-PD-1 antibody, nivolumab. The patient’s temperature was 39.5 °C, pulse rate was 120/min, and blood pressure was 95/60. Physical examination showed nausea and a known pelvic mass. The cardiopulmonary auscultation was normal. There were neither cutaneous nor mucous abnormalities. Allergic reaction was suspected. Infusion was stopped, antihistamine and corticosteroids (1 mg/kg of methylprednisolone) were administered. The patient remained febrile. Gram stain of a positive blood culture revealed bacillus Gram-positive bacteria. Combination therapy with amoxicillin and gentamicin was started. Finally, three blood cultures, one drawn from the port-a-cath and two from a peripheral vein returned positive for rapidly growing mycobacteria. The port-a-cath was removed and the antibiotics were switched to gentamicin, clarithromycin, and ethambutol. Transthoracic echocardiography revealed no sign of endocarditis. The isolate was sent to a local referral laboratory for identification and susceptibility testing. Identification to the species level was performed by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF mass spectrometry) (Vitek MS, BioMerieux®, Marcy l’Etoile, France), leading to Mycobacterium mucogenicum identification. In the absence of clinical information, M. mucogenicum was considered as a contaminant, and susceptibility testing was not performed. Nevertheless, diagnosis of M. mucogenicum port-a-cath related bloodstream infection was retained. Two weeks after starting antibiotic treatment, renal impairment urged its change. Usual susceptibility of M. mucogenicum motivated switch to clarithromycin and moxifloxacin. Our isolate was sent to the National Consultant Laboratory for Mycobacteria for sensitivity testing. Identification was confirmed through sequencing analysis of hsp65 gene. Susceptibility testing was performed by standard broth microdilution method using Sensititre® RAPMYCO panel. The isolate was susceptible to clarithromycin and moxifloxacin (Table 1). The occurrence of this infection prevented the poursuit of experimental infusion of nivolumab. After 2 months of combination antibiotherapy, cyclophosphamide was started because of worsening of peritoneal carcinomatosis. Antibiotics were pursued 6 months. No relapse of infection was observed after its discontinuation despite concomitant chemotherapy.
Table 1

Susceptibility testing of Mycobacterium mucogenicum isolate

Antimicrobial drugs

Minimal inhibitory concentration (mg/L)

Clinical breakpoints* (mg/L)

amikacin

2

16–64

tobramycin

8

2–8

ciprofloxacin

0.5

1–4

moxifloxacin

< 0.25

1–4

clarithromycin

0.5

2–8

linezolid

2

4–32

trimetoprim/sulfamethoxazole

< 0.25/4.75

2/38–4/76

cefoxitin

< 4

16–128

imipenem

< 2

4–32

doxycyclin

0.25

1–8

minocyclin

< 1

1–8

*Clinical breakpoints according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST)

Discussion

We report a new case of Mycobacterium mucogenicum catheter related bloodstream infection, occuring in an immunocompromised patient. M. mucogenicum belongs to the group of rapidly growing mycobacteria, which are ubiquitous environmental organisms. Previously known as M. chelonae-like organism, M. mucogenicum finally changed name because of its phylogenetic distance from M. chelonae, but closeness to M. fortuitum and because of its mucoid colonies [4].

Infections caused by rapidly growing mycobacteria have been increasingly reported during the past few years because of improvement of isolation and identification techniques and spread of medical conditions compromising immune system [1, 5]. These microorganisms have been shown to cause various infections, including bacteremia. M. mucogenicum is the most common rapidly growing mycobacteria implicated in catheter related bloodstream infections [2, 3]. Like other rapidly growing mycobacteria, it has a high predisposition to create biofilm and colonise intravascular devises. Isolates appear as Gram-positive bacteria on Gram stain. Acid-fast stain is positive. M. mucogenicum can be cultivated in Lowenstein-agar but also in routine culture media within 7 days. The current gold standard for the identification of mycobacteria is DNA sequencing with 16sRNA gene, rpoB, and hsp65 being recognized as useful targets [6, 7]. But these methods are not affordable in many laboratories. Several investigators have demonstrated that MALDI-TOF mass spectrometry could accurately identify mycobacteria [8, 9]. Since treatment and response rates differ widely depending on the mycobacterial species, rapid identification is essential. Prompt identification to the species level can predict in vitro susceptibility and guide the choice of initial antibiotic therapy. Despite the possibility of contamination, recovery of M. mucogenicum from the bloodstream especially in immune-compromised patients should be considered as a true pathogen. Susceptibility testing is indicated for any rapidly growing mycobacteria considered clinically significant. M. mucogenicum isolates are usually susceptible to aminoglycosides, fluoroquinolones, tetracyclines, macrolides, carbapenems, cefoxitin, trimethoprim-sulfamethoxazole, and linezolid [10]. Management of M. mucogenicum catheter-related bloodstream infections is mainly based on clinical experience. Optimal antibiotherapy is not established. In previously published case-series, an aminoglycoside combined with a macrolide and/or a quinolone was the most common empirical treatment [5, 11]. Optimal duration of treatment is unknown. At least 4 weeks of combination regimen were prescribed. But treatment may be prolonged in case of deep and persistent immunosuppression. Removal of the catheter is required to achieve successful outcome. Indeed, relapses have been associated with preservation of the catheter [3]. The mortality rate was usually low [3, 11].

Conclusion

M. mucogenicum is an emerging cause of catheter related bloodstream infection. Awareness of clinicians and microbiologists should be raised to avoid considering M. mucogenicum as a contaminant and delaying initiation of antibiotherapy. Absence of established therapeutic guidelines makes case reports relevant to increase data on various antibiotic regimen and prognosis.

Abbreviations

DNA: 

Deoxyribonucleic acid

MALDI-TOF: 

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

RNA: 

Ribonucleic acid

Declarations

Acknowledgements

None.

Funding

None.

Availability of data and materials

Not applicable.

Authors’ contributions

MP, AB and AM collected and analysed the data, and conceived the case report. EC collected the data and participated in the design of the case report. OR, ES analysed the data and drafted the manuscript. All the authors contributed to the clinical care of the patient and gave final approval of the version to be published.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report.

Competing interests

The authors declare that they have no competing interests.

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Authors’ Affiliations

(1)
Service Universitaire des Maladies Infectieuses et du voyageur, Centre Hospitalier Dron, 135 avenue du Président Coty, 59200 Tourcoing, France
(2)
Laboratoire de Microbiologie, Institut Gustave Roussy, Villejuif, France

References

  1. Redelman-Sidi G, Sepkowitz KA. Rapidly growing mycobacteria infection in patients with cancer. Clin Infect Dis. 2010;51:422–34.View ArticleGoogle Scholar
  2. El Helou G, Viola GM, Hachem R, Han XY, Raad II. Rapidly growing mycobacterial bloodstream infections. Lancet Infect Dis. 2013;13:166–74.View ArticleGoogle Scholar
  3. El Helou G, Hachem R, Viola GM, El Zakhem A, Chaftari AM, Jiang Y, et al. Management of rapidly growing mycobacterial bacteremia in cancer patients. Clin Infect Dis. 2013;56:843–6.View ArticleGoogle Scholar
  4. Springer B, Bottger EC, Kirschner P, Wallace RJ Jr. Phylogeny of the Mycobacterium chelonae-like organism based on partial sequencing of the 16S rRNA gene and proposal of Mycobacterium sp nov. Int J Syst Bacteriol. 1995;45:262–7.View ArticleGoogle Scholar
  5. Han XY, De I, Jacobson KL. Rapidly growing mycobacteria : clinical and microbiologic studies of 115 cases. Am J Clin Pathol. 2007;128:612–21.View ArticleGoogle Scholar
  6. Telenti A, Marchesi F, Balz M, Bally F, Böttger E, Bodmer T. Rapidly growing mycobacteria to the species level by polymerase chain reaction and restriction enzyme analysis. J Clin Microbiol. 1993;31:175–8.PubMedPubMed CentralGoogle Scholar
  7. Hall L, Doerr KA, Wohlfiel SL, Roberts GD. Evaluation of the MicrSeq system for identification of mycobacteria by 16S ribosomal DNA sequencing and its integration into a routine clinical mycobacteriology laboratory. J Clin Microbiol. 2003;41:1447–53.View ArticleGoogle Scholar
  8. Kodana M, Tarumoto N, Kawamuta T, Saito T, Ohno H, Maesaki S, et al. Utility of the MALDI-TOF MS method to identify nontuberculous mycobacteria. J Infect Chemother. 2016;22:32–5.View ArticleGoogle Scholar
  9. Buckwalter SP, Olson SL, Connelly BJ, Lucas BC, Rodning AA, Walchak RC, et al. Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of Mycobacterium species, Nocardia species, and other aerobic Actinomycetes. J Clin Microbiol. 2016;54:376–84.View ArticleGoogle Scholar
  10. Adekambi T. Mycobacterium mucogenicum group infections : a review. Clin Microbiol Infect. 2009;15:911–8.View ArticleGoogle Scholar
  11. Abidi MZ, Ledeboer N, Banerjee A, Hari P. Mycobacterium mucogenicum bacteremia in immune-compromised patients, 2008-2013. Diagn Microbiol Infect Dis. 2016;85:182–5.View ArticleGoogle Scholar

Copyright

© The Author(s). 2018

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