Mycobacterium chelonae infection in a corneal graft

Endophthalmitis Caused byMycobacterium Abscessus

PURPOSE

To describe the clinical and laboratory features of a case of endophthalmitis caused by Mycobacterium abscessus in a patient immunocompetent.

METHODS

case report. A 65-year-old woman with bilateral cataracts was treated by surgery with phacoemulsification and posterior chamber lens implantation.

RESULTS

The funduscopic examination showed vitreous cells over the optic nerve head, chorioretinal infiltrates, and focal vasculitis. Vitreous humor aspirate disclosed acid-fast bacilli. In the culture on Löwenstein-Jensen medium grew colonies identified as M. abscessus.

CONCLUSIONS

M. abscessus is cause of endophthalmitis and crystalline keratopathy. Risk factor include surgical intervention or exogenous contamination. Our patient has no systemic pathology predisposing to the development of endophthalmitis.

Rapidly Growing Mycobacteria

Rapidly growing mycobacteria (RGM) compose approximately one-half of the currently validated mycobacterial species and are divided into six major groups, including the Mycobacterium fortuitum group, M. chelonae/M. abscessus complex, M. smegmatis group, M. mucogenicum group, M. mageritense / M. wolinskyi , and the pigmented RGM. This review discusses each group and highlights the major types of infections associated with each group. Additionally, phenotypic and molecular laboratory identification methods, including gene sequencing, mass spectrometry, and the newly emerging whole-genome sequencing, are detailed, along with a discussion of the current antimicrobial susceptibility methods and patterns of the most common pathogenic species.

Antimicrobial susceptibility of nontuberculous mycobacteria from eye infections

PURPOSE

To characterize formerly designated atypical or nontuberculous mycobacteria (NTM) associated with eye infections.

METHODS

All clinical NTM eye isolates (112 isolates from 100 patients) submitted to a single national NTM reference laboratory between 1982 and 2009 were identified using polymerase chain reaction and restriction fragment length polymorphism of the hsp65 gene. Isolates were tested against 10 antimicrobials, including besifloxacin, a new 8-chloro-fluoroquinolone. Assessments included species of NTM recovered, year of isolation, type of eye infection, geographic location, and drug susceptibilities.

RESULTS

In the 1980s, the major pathogen isolated was Mycobacterium abscessus. In the 1990 s, Mycobacterium chelonae emerged as the major pathogen. By 2000, it was responsible for more than 50% of all cases. The majority of M. abscessus and Mycobacterium fortuitum were from southern coastal states and Texas, whereas M. chelonae isolates were more widespread geographically. The most active antimicrobials were amikacin and clarithromycin/azithromycin for M. abscessus and clarithromycin/azithromycin, amikacin, and tobramycin, and the quinolones for M. chelonae.

CONCLUSIONS

This is the largest study of NTM ophthalmic isolates to date and is the first to include susceptibilities and molecular identification for all isolates studied. This series establishes M. chelonae (44%) and M. abscessus (37%) as the NTM species most frequently associated with ophthalmic infections. Topical ophthalmic fluoroquinolones may have a role in the management of ocular infections involving M. chelonae and M. fortuitum.

Application of polymerase chain reaction-based restriction fragment length polymorphism in typing ocular rapid-growing nontuberculous mycobacterial isolates from three patients with postoperative endophthalmitis

PURPOSE

We describe postoperative endophthalmitis caused by rapid-growing nontuberculous mycobacteria (RGNTM) in 3 patients after small-incision cataract surgery with intraocular lens (IOL) implantation performed elsewhere and referred to us for management. Subsequent identification and confirmation was carried out with biochemical tests and polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP).

MATERIALS AND METHODS

The corneal scraping and eviscerated material of the first patient, the corneal button and the IOL of the second patient, and the corneal scraping of the third patient were processed for routine bacteriologic studies including acid-fast bacilli (AFB) by smear (excepting the IOL) and culture. Subsequent identification of the RGNTM was carried out by using biochemical tests and PCR-RFLP by using primers targeting the heat shock protein 65 region of mycobacteria.

RESULTS

AFB smear was positive in all 3 patients. The corneal scraping of the first patient, the corneal button and IOL of the second patient, and the corneal scraping of the third patient were culture positive for RGNTM and were identified as Mycobacterium abscessus in the first and second patients and M. fortuitum sorbitol-positive third biovariant in the third patient.

CONCLUSIONS

A clinical suspicion of infection by RGNTM in delayed-onset postoperative endophthalmitis should be considered when resistance to standard therapy is encountered.

Mycobacterium chelonae–Mycobacterium abscessus complex clear corneal wound infection with recurrent hypopyon and perforation after phacoemulsification and intraocular lens implantation

We report a clear corneal wound infection occurring in a 74-year-old man caused by a member of the Mycobacterium chelonae-Mycobacterium abscessus complex, presenting as crystalline keratopathy with recurrent hypopyon. This led to perforation after phacoemulsification with posterior chamber intraocular lens implantation. Only after corneal biopsy of the incision was the causative organism isolated and found to be sensitive to clarithromycin and ciprofloxacin. Despite aggressive therapy, a full-thickness corneal perforation developed, requiring emergent cyanoacrylate glue to preserve ocular integrity. Both the difficulty and delays in obtaining a correct diagnosis led to severe ocular morbidity. Infectious lamellar keratitis limited to the clear cornea phacoemulsification incision is rare, but some unusual organisms such as atypical mycobacteria may be encountered.

An unusual pathogen causing microbial keratitis

INTRODUCTION

We report a rare case of Mycobacterium fortuitum affecting the corneal graft of a patient 6 years post-graft, possibly associated with contact lens use.

CONCLUSIONS

This case shows the need for careful microbiological techniques when dealing with patients presenting with microbial keratitis. It must be kept in mind that unusual and slow growing organisms may also be responsible for corneal ulceration. If a slow growing organism is suspected, a microbiological diagnosis may not be forthcoming for weeks. Misidentification of the responsible pathogen may further complicate management for the clinicians. Cases such as these, which may not respond to medical therapy as expected, may prove a difficult therapeutic challenge to physicians.

An outbreak of Mycobacterium chelonae infection after LASIK

OBJECTIVE

To describe an outbreak of mycobacterial keratitis after laser in situ keratomileusis (LASIK), including the microbiologic investigation, clinical findings, treatment response, and outcome.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Patients (n = 10) who underwent LASIK surgery between August 22 and September 4, 2000, and developed mycobacterial infection.

METHODS

Patients were prospectively followed in relation to microbiologic investigation, clinical findings, treatment response, and outcome.

MAIN OUTCOME MEASURES

Most patients underwent bilateral simultaneous LASIK. Postoperative infection was signaled by the appearance of corneal infiltrates in the third postoperative week. The microbiologic workup was performed on cultures obtained either by direct scraping of the cornea or by lifting the flap. Medical therapy was instituted based on drug susceptibility testing. Surgical interventions such as corneal debridement and flap removal were performed during recurrences or when there was no satisfactory clinical response.

RESULTS

Cultures revealed Mycobacterium subspecies chelonae. Patients were treated with topical clarithromycin (1%), tobramycin (1.4%), and ofloxacin (0.3%). Oral clarithromycin (500 mg twice a day) was prescribed for those patients who did not respond clinically to topical treatment. Four eyes healed on this regimen. Flap removal was necessary in seven eyes.

CONCLUSIONS

This report highlights mycobacteria as an etiologic infectious agent after LASIK. Diagnosis can be difficult and is often delayed. The treatment mainstay is prolonged antibiotic therapy. Surgical debridement and flap removal may shorten the disease course.

Clinical and taxonomic status of pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria

The history, taxonomy, geographic distribution, clinical disease, and therapy of the pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria (RGM) are reviewed. Community-acquired disease and health care-associated disease are highlighted for each species. The latter grouping includes health care-associated outbreaks and pseudo-outbreaks as well as sporadic disease cases. Treatment recommendations for each species and type of disease are also described. Special emphasis is on the Mycobacterium fortuitum group, including M. fortuitum, M. peregrinum, and the unnamed third biovariant complex with its recent taxonomic changes and newly recognized species (including M. septicum, M. mageritense, and proposed species M. houstonense and M. bonickei). The clinical and taxonomic status of M. chelonae, M. abscessus, and M. mucogenicum is also detailed, along with that of the closely related new species, M. immunogenum. Additionally, newly recognized species, M. wolinskyi and M. goodii, as well as M. smegmatis sensu stricto, are included in a discussion of the M. smegmatis group. Laboratory diagnosis of RGM using phenotypic methods such as biochemical testing and high-performance liquid chromatography and molecular methods of diagnosis are also discussed. The latter includes PCR-restriction fragment length polymorphism analysis, hybridization, ribotyping, and sequence analysis. Susceptibility testing and antibiotic susceptibility patterns of the RGM are also annotated, along with the current recommendations from the National Committee for Clinical Laboratory Standards (NCCLS) for mycobacterial susceptibility testing.

Delayed-onset mycobacterial keratitis after LASIK

PURPOSE

To describe the time course, diagnosis, clinical features, and treatment of seven patients with Mycobacterium szulgai keratitis that developed from 7 to 24 weeks after laser in situ keratomileusis (LASIK).

METHODS

Seven of 30 eyes of 18 patients were identified with keratitis after LASIK. The first two patients presented 12 to 14 weeks after LASIK; nontuberculous mycobacteria were identified 1 month after the flaps were cultured. Patient recall identified three additional cases by culture and two cases by clinical features alone. Pulsed-field gel electrophoresis (PFGE) was used to type the isolates, and treatment was modified based on susceptibilities.

RESULTS

M. szulgai was identified in five patients for whom cultures were performed, but response to empiric therapy based on cultures proved unsatisfactory. The keratitis resolved in all patients with treatment including clarithromycin based on susceptibilities. Medical therapy was sufficient, although one patient required flap amputation. Six of seven patients recovered best-corrected visual acuity (BCVA), while one patient lost one line of BCVA. Two patients lost one line of postoperative uncorrected visual acuity (UCVA), two patients gained one line of UCVA, and three patients recovered postoperative UCVA. PFGE analysis revealed that the M. szulgai strains were identical, and the infection source was contaminated ice used to chill syringes for saline lavage.

CONCLUSIONS

Nontuberculous mycobacterial keratitis after LASIK is a diagnostic and management challenge, but outcomes can be preserved with treatment based on susceptibilities. This cluster underscores the importance of adherence to sterile protocol during LASIK.

A Cluster of cases of Mycobacterium szulgai keratitis that occurred after laser-assisted in situ keratomileusis

Laser-assisted in situ keratomileusis (LASIK) is a recently developed ophthalmic procedure. When 2 patients developed keratitis caused by Mycobacterium szulgai after they underwent LASIK surgery, we conducted a retrospective cohort study of all LASIK procedures performed at Scott & White Clinic (Temple, Texas) during a 4.5-month period. Seven patients had compatible symptoms and signs, 5 of whom had confirmed M. szulgai keratitis. Five cases occurred among 30 procedures performed by doctor A, and there were no cases among 62 procedures performed by doctor B (approximate relative risk, 12.0; 95% confidence interval, 1.6-679.0; P=.0029). Doctor A had chilled syringes of saline solution in ice for intraoperative lavage-the only factor that differentiated the procedures of the 2 surgeons. Cultures of samples from the source ice machine's drain identified M. szulgai; the strain was identical to isolates recovered from all confirmed cases and differed from 4 standard M. szulgai strains, as determined by pulsed-field gel electrophoresis. Intraoperative contamination from ice water apparently led to M. szulgai keratitis in these patients.