Project springfield

POSTSURGICAL KNEE INFECTION WITH MYCOBACTERIUM FORTUITUM AFTER A
TENDON REPAIR OF THE QUADRICEPS MUSCLE.
S. VORA1, MC. DESCOMBES2, J. MOSIMANN3, PA. MENOUD2 and R.AUCKENTHALER2
1Hôpital La Tour, Meyrin, 2Unilabs Coppet, Lausanne, Genève, 3IMD Zurich, Switzerland Abstract
Clinical HistoryA closed traumatic rupture of the tendon of the quadriceps muscle was repaired with resorbable and non-resorbable sutures in a 65 y. old male, without antibiotic prophylaxis. Two months later the patient presented withfever and a swollen inflamed knee with purulent discharge. The surgical exploration necessitated extended debridement of soft tissues and a partial resection of a necrotic patella. The patient was successfully treated withciprofloxacin and clarithromycin for 12 months.
MicrobiologyDirect examination of the pus revealed many leucocytes but no microorganisms were seen. From 5 different samples, small white colonies were growing aerobically after 3 days at 37°C on sheep blood agar and colistin-nalidixic acid agar, revealing Gram-positive, Ziehl-Neelsen-negative bacilli. The kit API Corynebacterium V3.0 showed a good identification as Corynebacterium propinquum (96.7%). Because of an unusual resistance tothe routine tested antibiotics, this identification was further checked with MALDI-TOF MS (Bruker Microflex instrument, Biotyper 2.0 reference database) which suggested the presence of Arthrobacter spp. Definitiveidentification as Mycobacterium fortuitum was obtained by comparative sequence analysis of a part of the hsp65 gene. The strain was resistant to imipenem and cotrimoxazole but susceptible to ciprofloxacin,clarithromycin, minocycline, tigecycline, linezolid and amikacin.
Discussion and conclusionMycobacterium fortuitum, a rapidly growing non-tuberculous mycobacterium (NTM) is a well-recognized, yet uncommon cause of soft tissue infection. However, the incidence of post surgical wound infections caused byrapidly growing NTMs is increasing. The presentation of such infection is often atypical and difficulties with the identification of these pathogens in the routine microbiology laboratory can cause diagnostic delay andincreased morbidity. At present, there is no universally accepted treatment protocol. Cure may be possible with extensive surgical debridement and a prolonged course of appropriate antimicrobial therapy.
Introduction
Mycobacterium fortuitum, a rapidly growing non-tuberculous mycobacterium (NTM) is a well-recognized, yet uncommon cause of soft tissue infection. However, theincidence of post surgical wound infections caused by rapidly growing NTMs is increasing. The presentation of such infection is often atypical and difficulties with theidentification of these pathogens in the routine microbiology laboratory can cause diagnostic delay and increased morbidity.
Clinical History
A closed traumatic rupture of the tendon of the quadriceps muscle was repaired with resorbable and non-resorbable sutures in a 65 years old male, without antibioticprophylaxis. Two months later the patient presented with fever and a swollen inflamed knee with purulent discharge. The surgical exploration necessitated extendeddebridement of soft tissues and a partial resection of a necrotic patella.
Microbiological Results
Characteristics
Gram Stain
Ziehl-Neelsen
• Gram positive bacilli, • Small colonies after 3 days 37°C on blood and chocolate agar • Catalase +• No growth on McConkey• Faint growth in Rosenow broth after 2 days• No anaerobic growth Identification
Laboratory
Identification
IMD, Zürich
M. senegalense respM. fortuitumM. farcinogenese resp Susceptibility
Unilabs Disk
IMM Zürich
NCCLS (E-test)
Institut für med.
Mikrobiologie, Zürich
Conclusion
• Mycobacterium fortuitum is a ubiquitous, non-tuberculous mycobacterial species known for rarely causing cutaneous disease, osteomyelitis, joint infections, ocular disease (keratitis, ulcer) and posttraumatic infections.
• Rapid growth on routinely used media and faintly gram-positive coloration lead to delay in diagnosis because of suspecting grampositive cocco-bacilli.
• Correct identification was obtained neither by a commercialized biochemical identification system (Corynebacterium spp) nor by MALDI-TOF (E. coli), but only by PCR 16S rRNA • The multiresistant pattern of susceptibility tests must evoke the presence of a References
• Clinical and taxonomic status of pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria. Clin Microbiol Rev. 2002; 15: 716-46• Mycobacterium fortuitum infection following patellar tendon repair. Hetsroni I et al. J Bone Joint Surg Am. 2010; 92:1254-6• Mycobacterium fortuitum infection following total knee arthroplasty: a case report and literature review. Knee. 2008; 15:61-3

Source: http://www.unilabs.ch/Lists/ScientificPublication/Poster%20M.%20fortuitum%20RA%20SSM%202010.pdf