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Year : 2014  |  Volume : 57  |  Issue : 2  |  Page : 335-337
Mycobacterium chelonae causing chronic wound infection and abdominal incisional hernia

1 Department of Microbiology, CSI Hospital, Bengaluru, Karnataka, India
2 Department of Surgery, CSI Hospital, Bengaluru, Karnataka, India

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Date of Web Publication19-Jun-2014


Mycobacterium chelonae is a rapidly growing mycobacterium that is found all over the environment, including sewage and tap water. They are important species associated with chronic non-healing wounds. We report a case in a 41 year old female patient who underwent multiple surgeries for an ovarian cyst, tubo-ovarian abscesses with peritonitis and a repair of an abdominal incisional hernia.

Keywords: Chronic wound infection, Mycobacterium chelonae, nontuberculous mycobacteria

How to cite this article:
Verghese S, Agrawal P, Benjamin S. Mycobacterium chelonae causing chronic wound infection and abdominal incisional hernia. Indian J Pathol Microbiol 2014;57:335-7

How to cite this URL:
Verghese S, Agrawal P, Benjamin S. Mycobacterium chelonae causing chronic wound infection and abdominal incisional hernia. Indian J Pathol Microbiol [serial online] 2014 [cited 2023 Sep 26];57:335-7. Available from:

   Introduction Top

Mycobacterium chelonae is a fast growing mycobacterium isolated from environmental sources. They are classified as part of the Mycobacterium fortuitum complex, and they come under the M. chelonae/abscessus group. They can cause nosocomial infections and have been associated with medical instruments such as bronchoscopes and laproscopes. They have been associated with chronic postoperative non-healing wounds.

   Case report Top

The patient was a 41 year old single, nulliparous female. She presented to our hospital in September 2012 with a history of a painful swelling in the infra umbilical region and a non-healing surgical scar. The swelling and sinus was present for 3 months and increased in size over a 3 week period. The swelling was sited over a previous abdominal incision. She did not give any history of fever, nausea, or vomiting or purulent discharge at the wound site. She had no symptoms related to her bowels.

In 2011, she underwent a laproscopic ovarian cystectomy. She was subsequently diagnosed a few months later, with bilateral tubo-ovarian mass at another hospital. She then underwent an abdominal hysterectomy, bilateral salpingo-oopherectomy and appendectomy and partial omentectomy. Postoperatively, her wound never completely healed. The biopsy report from the second hospital stated that she had bilateral tubo-ovarian abscesses with peritonitis. They demonstrated acid fast bacilli in the peritoneal fluid, which was never cultured. She was discharged after surgery but never received any treatment for the mycobacteria seen in the peritoneal fluid.

She was not a diabetic. She was on medication for mild hypertension.


She was afebrile, and her vital parameters were normal. Respiratory and cardiovascular systems were normal. The abdominal examination showed a tender, 5 cm, infra umbilical swelling and a sinus over a midline vertical scar. Cough impulse was noted in the swelling. A diagnosis of an irreducible nonobstructed incisional hernia was made.


Hemoglobin was 14.5 mg/dl. Total white blood cells were 6600/cmm, polymorphs 66%, lymphocytes 33% eosinophils 1%. Platelet count was 2.5 lakhs/cmm. Packed cell volume was 43.2%. Random blood sugar was 117 mg/dl. Creatinine was 1 mg/dl. HIV and Hepatitis B surface antigen were nonreactive.

Surgery was performed under the cover of a first generation cephalosporin. The previous scar tissue was excised. There was minimal pus discharging from the lower end of the previous scar. This was sent for culture. An in-lay hernioplasty was done for the hernia despite the infection.

Postoperatively, she remained on antibiotics and the immediate recovery was uneventful. At follow up on the 10 th day, when the sutures were removed, the wound broke down and there was a sinus measuring 5 cm discharging thin watery pus [Figure 1].
Figure 1: Nonhealing infra umbilical scar and sinus

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The direct smear from the pus was negative for acid fast bacillus (AFB), but the culture grew moderate growth of off white dry colonies on all media, such as blood agar, chocolate agar and MacConkey agar and thioglycholate broth within 4 days of incubation.

This growth stained positive for acid fast bacillus. This rapidly growing mycobacteria was found to be sensitive to amikacin, gentamycin, netilmycin, azithromycin, linezolid, and cotrimoxazole, but was resistant to all quinalones including ciprofloxacin, ofloxacin, laevofloxacin and also rifampicin. The strain was resistant (no zone) to polymyxin B (300 μg) and sensitive to amikacin (30 μg). Hence it was presumptively identified as Mycobacteria chelonea [Figure 2].
Figure 2: Resistance to polymyxin B disc (300 μg) and sensitivity to amikacin (30 μg) disc

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The patient was started on amikacin 750 mg/day along with azithromycin 500 mg BD which was given for 2 weeks. This was followed by linezolid 500 mg BD along with azithromycin 500 mg BD for 6 weeks.

The wound healed completely and the mesh was intact.

   Discussion Top

Mycobacterium chelonae is a rapidly growing mycobacterium that is found all over the environment, including sewage and tap water. It has been implicated as a cause of opportunistic infections in humans.

These mycobacteria are involved in cases of community-acquired infections of skin and soft tissue, following puncture wounds from stepping on nails and due to open lacerations or fractures.

Mycobacterium chelonae can be isolated from a wide range of environmental sources such as tap water and other sources of water including water tanks and industrial sources. [1]

It has also been found on medical instruments such as bronchoscopes. [2] This can give rise to pseudo-outbreaks of infection, such as that which occurred when a cleaning water reservoir used in bronchoscope cleaning was found to contain M. chelonae. [2]

In Bangalore, [3] a series of 145 laparoscopy port site infections due to M. chelonae were found in 35 patients following laparoscopy at a single hospital over a 6-week period. The contaminating source was ultimately identified as the rinsing water used for washing chemically disinfected instruments.

Our patient also gave a history of laproscopic ovarian cystectomy which was probably the source of mycobacterial infection of the peritoneal cavity.

The clues for diagnosis are persistent discharge, multiple abscesses, non-healing postoperative wound and failure to grow any organism on routine culture. Presumptive diagnosis can be done with the clinical history, but demonstrating AFB and/or a positive culture for mycobacteria is required to make a definitive diagnosis. [4] Even after the growth of the of the organism, the isolate can be confirmed by either biochemical reactions or the more recent nucleic acid amplification tests. But there have been reports that even these tests could give a false positive diagnosis. [4]

Resistance to polymyxin B disc (300 μg) can be the easiest and the most accurate method for rapid presumptive identification of M. chelonae. Of the 75 isolates of M. fortuitum tested, 100% produced 10 mm or more zone diameters of inhibition to polymyxin B (300 μg) disc, whereas 0% of the 58 strains of M. chelonae produced any zone of inhibition. [5]

With an amikacin (30 μg) disc, 99% of 75 isolated strains of M. fortuitum, gave a zone diameter of >30 mm while only 6% of 58 strains M. chelonae produced >30 mm zone diameter. Hence this method can be used for rapid presumptive identification of rapidly growing mycobacteria. [5]

Catheter-related nosocomial infections are seen most often with long term central intravenous catheter, but they may occur with peritoneal or shunt catheters. M. chelonae is an increasingly recognized agent of keratitis, especially after injury with a foreign body or following office ophthalmologic procedures. It can be identified in culture, producing visible growth on agar within a week.

In the skin, M. chelonae is seen as a cause of infections such as abscesses with draining sinuses and increasingly in areas that have been subject to cosmetic procedures. Now classified as part of the M. fortuitum complex, it is closely related to M. abscessus, sometimes known as the M. chelonae/abscessus group. [6]

First-line antituberculous drugs (e.g., isoniazid, rifampcin, pyrazinamide) have no role in the treatment of M. chelonae infection. [7]

Although numerous reports have documented cases of successful therapy with one drug (e.g., clarithromycin), reports also describe the development of resistance to treatment. Antibiotic therapy with two drugs is preferable in most patients. [8]

Clarithromycin and azithromycin have both been used successfully. Amikacin is the preferred aminoglycoside for treating rapidly growing mycobacteria; however, tobramycin remains the most active aminoglycoside against M. chelonae. Ciprofloxacin and levofloxacin have activity against these organisms. Of these, ciprofloxacin has been used most often, but levofloxacin has better in vitro activity. Linezolid has good in vitro activity against M. chelonae and has been used successfully alone and in combination to treat infections with this organism. [9]

Our patient was on a 2 week course of amikacin 750 mg IM once daily and Azithromycin 500 mg twice daily followed by azithromycin and linezolid 600 mg twice daily for 6 weeks. Her wound has healed completely. The isolate was found to be resistant to the quinalones.

Treatment options have been found to vary depending on the stage of the disease. Small lesions usually improve under antibiotics and local wound care. Extensive lesions and antibiotic resistance require surgical debridement. In most patients, the use of two drugs may be required. [10]

However, even an organism such as this, which is often regarded as having low pathogenic potential, has a number of virulence determinants that are likely to play key roles in infection.

   References Top

1.Khan IU, Selvaraju SB, Yadav JS. Occurrence and characterization of multiple novel genotypes of Mycobacterium immunogenum and Mycobacterium chelonae in metalworking fluids. FEMS Microbiol Ecol 2005;54:329-38.  Back to cited text no. 1
2.Gubler JG, Salfinger M, von Graevenitz A. Pseudoepidemic of nontuberculous mycobacteria due to a contaminated bronchoscope cleaning machine. Report of an outbreak and review of the literature. Chest 1992;101:1245-9.  Back to cited text no. 2
3.Vijayaraghavan R, Chandrashekhar R, Sujatha Y, Belagavi CS. Hospital outbreak of atypical mycobacterial infection of port sites after laparoscopic surgery. J Hosp Infect 2006;64:344-7.  Back to cited text no. 3
4.Jayashree KV, Appalaraju B, Jayalakshmi J, Sowmya N, Jayachandran K, Balashanmugam TS, et al. When molecular diagnosis went wrong. Indian J Pathol Microbiol 2011;54:418-9.  Back to cited text no. 4
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5.Wallace RJ Jr, Swenson JM, Silcox VA, Good RC. Disk diffusion testing with polymyxin and amikacin for differentiation of Mycobacterium fortuitum and Mycobacterium chelonae. J Clin Microbiol 1982;16:1003-6.   Back to cited text no. 5
6.Brown-Elliott BA, Wallace RJ. Infections caused by nontuberculous mycobacteria. In: Mandell GL, Bennett JE, Dolin R, editors. Principles and Practice of Infectious Diseases. 6 th ed. Philadelphia: Elsevier Churchill Livingstone; 2005. p. 2090-916.  Back to cited text no. 6
7.Heifets LB. Antimycobacterial drugs. Semin Respir Infect 1994;9:84-103.  Back to cited text no. 7
8.Tebas P, Sultan F, Wallace RJ Jr, Fraser V. Rapid development of resistance to clarithromycin following monotherapy for disseminated Mycobacterium chelonae infection in a heart transplant patient. Clin Infect Dis 1995;20:443-4.  Back to cited text no. 8
9.Wallace RJ Jr, Brown-Elliott BA, Ward SC, Crist CJ, Mann LB, Wilson RW. Activities of linezolid against rapidly growing mycobacteria. Antimicrob Agents Chemother 2001;45:764-7.  Back to cited text no. 9
10.Brown-Elliott BA, Nash KA, Wallace RJ Jr. Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria. Clin Microbiol Rev 2012;25:545-82.  Back to cited text no. 10

Correspondence Address:
Susan Verghese
Department of Microbiology, CSI Hospital, Bengaluru - 560 051, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.134736

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