Nontuberculous mycobacterial keratitis in south Florida

Cure of mycobacterium avium keratitis caused by trauma in elderly: case report

We report a case of Mycobacterium avium keratitis, first detected in the laboratory, which is from an 81-year-old female patient with a 13-year history of recurrent keratitis after eye injuries. This patient underwent anterior chamber irrigation of the right eye, and autologous conjunctival flap covering plus medication, and the corneal ulcer healed. She recovered well after continuing with the medication for half a year. The patient was not immune-compromised. Complex eye diseases such as blurred vision and cataracts caused by advanced age, delayed symptoms caused by slow growth of Mycobacterium avium and low-grade inflammation, difficulty with laboratory culture, repeated medication use, and repeated illnesses were the main reasons for the prolonged failure to clarify the etiology of this case. Morphological examination provided important clues for the initial discovery of pathogenic bacteria. Remind to pay attention to the morphology of Mycobacterium under Gram staining and Rui's Giemsa staining. Acid fast staining and Deoxyribonucleic Acid(DNA) microarray chip method can be used as indicators for rapid diagnosis of Mycobacterium species.

Atypical microbial keratitis

Atypical microbial keratitis refers to corneal infections caused by micro-organisms not commonly encountered in clinical practice. Unlike infections caused by common bacteria, cases of atypical microbial keratitis are often associated with worse clinical outcomes and visual prognosis. This is due to the challenges in the identification of causative organisms with standard diagnostic techniques, resulting in delays in the initiation of appropriate therapies. Furthermore, due to the comparatively lower incidence of atypical microbial keratitis, there is limited literature on effective management strategies for some of these difficult to manage corneal infections. This review highlights the current management and available evidence of atypical microbial keratitis, focusing on atypical mycobacteria keratitis, nocardia keratitis, achromobacter keratitis, and pythium keratitis. It will also describe the management of two uncommonly encountered conditions, infectious crystalline keratopathy and post-refractive infectious keratitis. This review can be used as a guide for clinicians managing patients with such challenging corneal infections.

Ocular Mycobacterium haemophilum infection originating in the cornea: a case report

BACKGROUND

Mycobacterium haemophilum is a slow-growing non-chromogenic nontuberculous Mycobacterium species that can cause skin infection or arthritis in an immunocompromised population or in children. Primary infection of the healthy adult cornea is rare. The special requirements for culture make this pathogen difficult to diagnose. The study aims to report the clinical manifestation and treatment process of corneal infection and notify the awareness of M. Haemophilus keratitis among clinicians. This is the first case report of primary M. haemophilum infection in the cornea of healthy adults reported in the literature.

CASE PRESENTATION

A 53-year-old healthy goldminer presented with left eye redness and a history of vision loss for four months. The patient was misdiagnosed with herpes simplex keratitis until M. haemophilum was detected using high-throughput sequencing. Penetrating keratoplasty was performed, and a large number of mycobacteria were detected by Ziehl-Neelsen staining of the infected tissue. Three months later, the patient developed conjunctival and eyelid skin infections that manifested as caseous necrosis of the conjunctiva and skin nodules. After excision and debridement of the conjunctival lesions and systemic antituberculosis drug treatment for 10 months, the patient was cured.

CONCLUSION

M. haemophilum could cause primary corneal infection in healthy adults, which is an infrequent or rare infection. Owing to the need for special bacterial culture conditions, conventional culture methods do not provide positive results. High-throughput sequencing can rapidly identify the presence of bacteria, which aids in early diagnosis and timely treatment. Prompt surgical intervention is an effective treatment option for severe keratitis. Long-term systemic antimicrobial therapy is crucial.

Outcomes of Nontuberculous Mycobacterial Keratitis After Clear Corneal Incision Phacoemulsification Surgery: A Case Series of 6 Eyes in South Florida

PURPOSE

The purpose of this study was to present the successful management and outcomes in a series of 6 cases of culture-positive nontuberculous mycobacterial keratitis after clear corneal incision phacoemulsification surgery.

METHODS

This is a case series of 6 consecutive eyes that presented at the Cornea Division at an academic institution, diagnosed with culture-positive nontuberculous mycobacterial keratitis after phacoemulsification surgery.

RESULTS

Six eyes of 5 patients were included. The mean interval from cataract surgery to presentation was 7.7 weeks. All cases presented with intrastromal abscesses adjacent to corneal incisions, and 2 had scleral extension of the infection. Isolated organisms were Mycobacterium abscessus (n = 4), Mycobacterium chelonae (n = 1), and Mycobacterium mucogenicum (n = 1). All cases were treated with topical amikacin 8 mg/mL for 10.5 weeks on average. All cases received either oral clarithromycin at 500 mg twice-daily dosage or oral azithromycin at 500 mg daily. Two patients with scleral abscesses underwent surgical debridement with amniotic membrane grafts. All 6 eyes achieved infection resolution and good visual recovery, with the final visual acuity ranging from 20/20 to 20/60. None of the patients experienced recurrence of infection.

CONCLUSIONS

Prompt medical treatment with combined topical and oral therapy can lead to infection resolution and favorable visual recovery. Early surgical intervention can ensure good outcomes in cases of scleral extension.

Clinical and demographic study of non-tuberculous mycobacterial ocular infections in South India

PURPOSE

To describe demographics, risk factors, antibiotic susceptibility, management and outcomes of ocular infections caused by non-tuberculous mycobacteria (NTM).

METHODS

A retrospective review of medical case records and microbiology records of patients with ocular infections that were culture positive for non-tuberculous Mycobacteria from January 2014 to December 2018 was done. Antibiotic susceptibility profile was done based on the CLSI guidelines. Laboratory diagnosis for the NTM Species was done by conventional microbiological methods. The species identification was done for stored isolated utilizing polymerase chain reaction targeting 16S rDNA and rpoB gene, followed by DNA sequencing and phylogenetic analysis.

RESULTS

Twenty patients with NTM ocular infections were identified during the study period. A majority of cases presented as 12 infectious keratitis (60%) and three suture-related corneal infiltrates (15%). Common risk factors were history of trauma in 9 (45%) patients and history of ocular surgery in 5 (25%) patients. Patients were treated with combination of amikacin and flouroquinolones/chloramphenicol (70%) and surgical interventions were performed in 25% cases. Only twelve isolates were stored and ten isolates were identified as the M. abscessus subsp. abscessus and two isolates as M. abscessus subsp. massiliense by sequencing and phylogenetic analysis. Majority of the NTM were sensitive to amikacin (75%) followed by moxifloxacin, ciprofloxacin, cephotaxime and tobramycin (35%).

CONCLUSION

High degree of clinical suspicion, multidrug antibiotic therapy and timely surgical intervention in patients with NTM infections, are advised for better clinical outcomes. Prior ocular trauma, prior ocular surgery and presence of biomaterials were the major predisposing factors. Earlier surgical intervention in cases where abscesses or biomaterials are involved, is necessary for rapid recovery.

Discovery of a novel Mycobacterium asiaticum PRA-hsp65 pattern

Twenty-one pulmonary sputum samples from nine Brazilian patients were analyzed by the PRA-hsp65 method for identification of Mycobacterium species and the results were compared by sequencing. We reported a mutation at the position 381, that generates a suppression cutting site in the BstEII enzyme, thus leading to a new PRA-hsp65 pattern for M. asiaticum identification.

Bilateral Non-tuberculous Mycobacterial Keratitis After Small Incision Lenticule Extraction

PURPOSE

To report a case of bilateral non-tuberculous mycobacterial keratitis after small incision lenticule extraction (SMILE) that was successfully treated with oral and topical fortified antibiotics.

METHODS

Case report and literature review.

RESULTS

An otherwise healthy 21-year-old woman presented with culture-proven bilateral Mycobacterium abscessus keratitis 8 days after undergoing SMILE, showing multiple white stromal infiltrates in the interface in both eyes. Progressive, diffuse flap edema followed by pocket abscess, exudation in the anterior chamber, granulation tissue formation in the pocket, intrastromal neovascularization, and eventually partial resolution of corneal opacity were noted after topical and oral antibiotic treatment for 6 months. Her corrected distance visual acuity was 20/32 and 20/50 in the right and left eyes, respectively, 12 months after initial presentation.

CONCLUSIONS

This is the first report of successful medical management of bilateral non-tuberculous mycobacterial keratitis after SMILE. The manifestations are different from and even more difficult to treat than those of keratitis after LASIK. [J Refract Surg. 2018;34(9):633-636.].

Mycobacterium Chelonae Keratitis in a Patient with SjöGren's Syndrome

Purpose

In this report a case of Mycobacterium chelonae keratitis in a patient without any previously described risk factors is described. The only risk factor found was a rheumatoid arthritis related Sjögren's syndrome.

Methods

Case report.

Results

A 60-year-old woman was referred to the hospital with an infectious keratitis of the left eye of 3 months duration, unresponsive to empirical therapy with ofloxacin and tobramycin drops. Her medical history included a longstanding rheumatoid arthritis and a secondary ocular surface syndrome. Upon arrival the left eye showed diffuse corneal edema and centrally several large infiltrates with fluffy edges, surrounded by several smaller satellite infiltrates. The cornea was scraped for culture and grew M chelonae and sensitivity testing showed sensitivity to ciprofloxacin, clofazimine, and clarithromycin. Systemically ciprofloxacin 750 mg and clarithromycin 500 mg twice daily were prescribed orally. Topical therapy consisted of topical erythromycin 10 mg/mL and ofloxacin 3 mg/mL every 2 hours. Treatment was continued for a total of 10 months during which the infiltrates cleared completely, but the central cornea remained scarred.

Conclusions

M chelonae can be a cause of infectious keratitis in patients without known risk factors for rapidly growing mycobacterium keratitis. Especially in the case of ocular infections that show no response to regular antibacterial treatment, mycobacterial infection should be considered. Good communication between the ophthalmologist and the microbiologist is crucial for a rapid diagnosis.

Delayed onset Mycobacterium intracellulare keratitis after laser in situ keratomileusis: A case report and literature review

RATIONALE

Infectious keratitis is a relatively uncommon but potentially sight-threatening complication of laser in situ keratomileusis (LASIK). Mycobacterial keratitis is usually regarded as late onset keratitis among post-LASIK keratitis. There has been no documented case of Mycobacterium intracellulare post-LASIK keratitis of a long-latent period.

PATIENT CONCERNS

A 36-year-old man was referred to our out-patient clinic, for persistent corneal epithelial defect with intrastromal infiltration. He had undergone uneventful bilateral LASIK procedure 4 years before. He complained decreased vision, accompanied by ocular pain, photophobia, and redness in his left eye for 7 months.

DIAGNOSIS

Lamellar keratectomy was taken using femtosecond laser. Bacterial culture with sequenced bacterial 16s ribosomal DNA confirmed the organism to be M intracellulare.

INTERVENTIONS

After 3 months of administration of topical clarithromycin, amikacin, and moxifloxacin, the corneal epithelial defect was resolved and the infiltration was much improved. However, newly developed diffuse haziness with surrounding granular infiltration in the central cornea was noted. Drug toxicity was suspected and topical moxifloxacin was discontinued, resulting in resolution of the diffuse haze with infiltration.

OUTCOME

The patient was followed up regularly without medication thereafter and recurrence was not found for 7 years.

LESSONS

This case presents the first case of M intracellulare keratitis after LASIK. LASIK surgeons should aware that post-LASIK keratitis can develop long after the operation and careful suspicion of infectious disease with meticulous diagnostic test is needed.

Discovery of novel antimycobacterial drug therapy in biofilm of pathogenic nontuberculous mycobacterial keratitis

PURPOSE

The potential of slow-growing mycobacteria to form biofilms in human tissues contributes to the problem of establishing an effective treatment strategy. The purpose of this study was to examine new antibiotic strategies to enhance current treatment options for these infections.

METHODS

Sensitivities of Mycobacterium fortuitum ATCC 49404 and Mycobacterium chelonae ATCC 35752 were evaluated for different antimicrobials singly and in combination using broth microdilution and FICI (Fractional Inhibitory Concentration Index) synergy screening. Anti-biofilm effects were evaluated in an 8-well chamber slide biofilm model. The efficacy of a new treatment strategy was validated using the novel neutropenic mouse keratitis model and monitored by slit-lamp microscopy, confocal microscopy, and colony forming unit measurements.

RESULTS

We reported the very first evidence that these organisms develop corneal biofilms by the accumulation of extracellular DNA (eDNA) and the presence of microcolonies using a novel mycobacterial neutropenic mouse keratitis model. The combination of amikacin and gatifloxacin or besifloxacin was more effective than the current gold-standard drug, amikacin, and we developed a novel treatment strategy (amikacin + gatifloxacin + DNase), the destruction of biofilm matrix component, eDNA, which increased the efficacy of the new antibiotic combination for treating mycobacterial infection in in vitro (P = 0.002) and in vivo (P = 0.001) compared to its respective control.

CONCLUSION

Biofilms have a role in mycobacterial keratitis leading to poor treatment outcomes in clinical practice and the use of combination therapy (amikacin + gatifloxacin + DNase) could be a useful new treatment option.

Endophthalmitis Caused by Nontuberculous Mycobacterium: Clinical Features, Antimicrobial Susceptibilities, and Treatment Outcomes

PURPOSE

To report the clinical features, antibiotic susceptibilities and treatment outcomes in patients with endophthalmitis caused by nontuberculous mycobacterium.

DESIGN

Noncomparative, consecutive case series.

METHODS

Retrospective chart review between December 1990 and June 2014.

RESULTS

In the 19 study patients, the clinical setting of endophthalmitis included post-cataract surgery (7/19, 36.8%), post-glaucoma implant (6/19, 31.6%), post-intravitreal injection (2/19, 10.5%), endogenous endophthalmitis (2/19, 10.5%), post-pars plana vitrectomy (1/19, 5.3%), and post-scleral buckle exposure (1/19, 5.3%). Chronic recurrent or persisting ocular inflammation was present in 15 of 19 patients (78.9%). The species isolated were Mycobacterium chelonae in 14 patients (73.7%), M fortuitum in 3 patients (15.8%), M triplex in 1 patient (5.3%), and M avium intracellulare in 1 patient (5.3%). Antibiotic susceptibilities to tested isolates were the following: amikacin (14/16; 87.5%) and clarithromycin (12/16, 75.0%). Intravitreal injections of amikacin (0.4 mg/0.1 mL) were given in 14 of 19 patients (73.7%) with an average of 7 injections per patient (range, 1-24 injections). Intraocular lens removal was performed for 6 of 7 patients (85.7%) with post-cataract surgery endophthalmitis. All the patients with glaucoma implant (6/6, 100%) underwent implant removal. At last follow-up, 6 of 19 patients (31.6%) had best-corrected visual acuity of 20/400 or better.

CONCLUSION

Endophthalmitis caused by nontuberculous mycobacterium often included chronic recurrent or persistent intraocular inflammation and frequently required removal of ocular device (intraocular lens, glaucoma implant, or scleral buckle). The majority of the isolates were susceptible to amikacin and clarithromycin. Visual outcomes in these patients even after treatment were generally poor.

Biofilms of Pathogenic Nontuberculous Mycobacteria Targeted by New Therapeutic Approaches

Microbial infections of the cornea are potentially devastating and can result in permanent visual loss or require vision-rescuing surgery. In recent years, there has been an increasing number of reports on nontuberculous mycobacterial infections of the cornea. Challenges to the management of nontuberculous mycobacterial keratitis include delayed laboratory detection, low index of clinical suspicion, poor drug penetration, slow response to therapy, and prolonged use of antibiotic combinations. The ability of nontuberculous mycobacteria to evade the host immune response and the ability to adhere and to form biofilms on biological and synthetic substrates contribute to the issue. Therefore, there is an urgent need for new antimicrobial compounds that can overcome these problems. In this study, we evaluated the biofilm architectures for Mycobacterium chelonae and Mycobacterium fortuitum in dynamic flow cell chamber and 8-well chamber slide models. Our results showed that mycobacterial biofilms were quite resistant to conventional antibiotics. However, DNase treatment could be used to overcome biofilm resistance. Moreover, we successfully evaluated a new antimicrobial compound (AM-228) that was effective not only for planktonic mycobacterial cells but also for biofilm treatment and was compared favorably with the most successful “fourth-generation” fluoroquinolone, gatifloxacin. Finally, a new treatment strategy emerged: a combination of DNase with an antibiotic was more effective than an antibiotic alone.

Use of Topical Besifloxacin in the Treatment of Mycobacterium chelonae Ocular Surface Infections

PURPOSE

To present the clinical outcome of 3 cases of ocular surface infections by Mycobacterium chelonae treated with besifloxacin (0.6%, Besivance; Bausch & Lomb, Tampa, FL).

METHODS

In this retrospective review of a small case series, we reviewed the medical records of 3 clinical patients with M. chelonae infection involving the ocular surface. Besifloxacin was used as an adjunct in 2 cases of keratitis and as the principal therapeutic agent in a case of nodular conjunctivitis.

RESULTS

Two patients who presented with culture-proven M. chelonae keratitis initially had been treated with topical amikacin and oral clarithromycin for 6 months in the first case and for 2 months in the second without complete resolution. Topical besifloxacin was added as an adjunct therapy to amikacin with progressive weaning of clarithromycin. Both cases of keratitis eventually resolved without recurrence after discontinuation of topical amikacin and besifloxacin. A third patient presented with nodular conjunctival inflammation, which initially had been treated with topical ciprofloxacin and corticosteroids without improvement. One nodular lesion was excised and submitted for microbial culture, which revealed the growth of M. chelonae. Marked improvement of the conjunctivitis was noted after 3 weeks of treatment with topical besifloxacin. Complete resolution of the conjunctival nodules was achieved after 10 weeks of treatment with besifloxacin.

CONCLUSIONS

Topical besifloxacin seems to be a useful adjunct agent in the treatment of nontuberculous mycobacterial keratitis by M. chelonae and may be viable for use as a first-line agent in cases of nodular conjunctivitis by M. chelonae.

Nontuberculous Mycobacterial Ocular Infections: A Systematic Review of the Literature

Nontuberculous or atypical mycobacterial ocular infections have been increasing in prevalence over the past few decades. They are known to cause periocular, adnexal, ocular surface and intraocular infections and are often recalcitrant to medical therapy. These infections can potentially cause detrimental outcomes, in part due to a delay in diagnosis. We review 174 case reports and series on nontuberculous mycobacterial (NTM) ocular infections and discuss etiology, microbiology, risk factors, diagnosis, clinical presentation, and treatment of these infections. History of interventions, trauma, foreign bodies, implants, contact lenses, and steroids are linked to NTM ocular infections. Steroid use may prolong the duration of the infection and cause poorer visual outcomes. Early diagnosis and initiation of treatment with multiple antibiotics are necessary to achieve the best visual outcome.

Nontuberculous mycobacterial ocular infections--comparing the clinical and microbiological characteristics between Mycobacterium abscessus and Mycobacterium massiliense

Purpose

To analyze the clinical characteristics of nontuberculous mycobacterial (NTM) ocular infections and the species-specific in vitro antimicrobial susceptibility.

Material and Methods

In 2000 to 2011 at the National Taiwan University Hospital, multilocus sequencing of rpoB, hsp65 and secA was used to identify NTM isolates from ocular infections. The clinical presentation and treatment outcomes were retrospectively compared between species. Broth microdilution method was used to determine the minimum inhibitory concentrations of amikacin (AMK), clarithromycin (CLA), ciprofloxacin (CPF), levofloxacin (LVF), moxifloxacin (MXF) and gatifloxacin (GAF) against all strains. The activities of antimicrobial combinations were assessed by the checkerboard titration method.

Results

A total of 24 NTM strains (13 Mycobacterium abscessus and 11 Mycobacterium massiliense) were isolated from 13 keratitis, 10 buckle infections, and 1 canaliculitis cases. Clinically, manifestations and outcomes caused by these two species were similar and surgical intervention was necessary for medically unresponsive NTM infection. Microbiologically, 100% of M. abscessus and 90.9% of M. massiliense ocular isolates were susceptible to amikacin but all were resistant to fluoroquinolones. Inducible clarithromycin resistance existed in 69.3% of M. abscessus but not in M. massiliense isolates. None of the AMK-CLA, AMK-MXF, AMK-GAF, CLA-MXF and CLA-GAF combinations showed synergistic or antagonistic effect against both species in vitro.

Conclusions

M. abscessus and M. massiliense are the most commonly identified species for NTM ocular infections in Taiwan. Both species were resistant to fluoroquinolones, susceptible to amikacin, and differ in clarithromycin resistance. Combined antimicrobial treatments showed no interaction in vitro but could be considered in combination with surgical interventions for eradication of this devastating ocular infection.

Draft Genome Sequence of Mycobacterium asiaticum Strain DSM 44297

We report the draft genome sequence of Mycobacterium asiaticum strain DSM 44297, a tropical mycobacterium seldom responsible for human infection. The genome of M. asiaticum has a size of 5,935,986 bp, with a 66.03% G+C content, encoding 5,591 proteins and 81 RNAs.

Ocular penetration and pharmacokinetics of topical clarithromycin eye drops to rabbits

PURPOSE

To evaluate the ocular pharmacokinetics of clarithromycin (CLA) eye drops topically applied to the corneas of rabbits.

METHODS

One 50-μL drop of CLA (0.25%) was administered to each New Zealand white rabbit in a single dose group, and one 50-μL drop of CLA was administered 6 times at 5-min intervals to each rabbit in a loading dose group. The effect of debridement on corneal penetration was also investigated in a de-epithelium group. The drug concentrations in the cornea and aqueous humor (AH) were assayed using high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) analysis.

RESULTS

Maximum CLA levels were achieved in the corneas and AH at 15 and 60 min, respectively, in the intact epithelium eyes in the single dose group (24.54±10.64 μg/g and 0.78±0.22 μg/mL, respectively, mean±the standard error of the mean, n=8). In the loading dose group, 30 min after the last application, the CLA level in the corneas reached 92.26±17.62 μg/g. In the loading dose group, the drug levels in the corneas and AH were significantly increased compared with the drug levels in the corneas with the intact epithelium and de-epithelium eyes in the single dose group at the corresponding time points (P<0.05). The estimated CLA half-lives in the corneas and AH for the intact eyes were 103.28 and 132.61 min, respectively.

CONCLUSION

Therapeutic CLA levels can be achieved in rabbit corneas after topically applying the drug with eye drops.

Pharmacological treatment for infectious corneal ulcers

INTRODUCTION

Cornea ulceration and infectious keratitis are leading causes of corneal morbidity and blindness. Infectious causes are among the most frequent and most severe. Management strategies for bacterial corneal ulcers have changed significantly over the last decades, however with a more limited progress in the treatment and management of nonbacterial, infectious ulcers.

AREAS COVERED

This paper provides an overview of the current principles, strategies and treatment choices for infectious corneal ulcers in adults.

EXPERT OPINION

Topical application with a broad-spectrum antimicrobial remains the preferred method for the pharmacological management of infectious corneal ulcers. Increasing reports of clinical failures and in vitro resistance to antibiotics to treat the most common infectious (bacterial) corneal ulcers are increasing concerns. New approaches for improvement in the pharmacological management of corneal ulcers should focus on strategies for a more rational and evidence-based use of current antimicrobials and development of products to modulate the host immune response and to neutralize microbial toxins and other immune modulators.

Non-tuberculous mycobacterial keratitis

Non-tuberculous mycobacteria are environmental, opportunistic pathogens that are increasingly being recognized as important causes of many human diseases. Among them, rapidly growing mycobacteria are the most notorious organisms causing infectious keratitis. Non-tuberculous mycobacterial (NTM) keratitis commonly occurs after trauma or refractive surgery, and can masquerade as fungal, herpetic or amoebic keratitis. Therefore, the diagnosis is often delayed. Prolonged medical treatment and judicious surgical debridement are required in order to eradicate the pathogens. Combination therapy with aminoglycosides, macrolides and fluoroquinolones improves the prognosis and decreases the occurrence of drug resistance. However, regardless of the development of new diagnostic techniques and antimicrobials, NTM keratitis remains a clinical challenge for most ophthalmologists. In this article, we provide a concise introduction to the epidemiological features and clinical characteristics of NTM keratitis, and the modern diagnostic tools used for it. We also summarize the current concepts of prevention and treatment for this potentially devastating condition.

Nontuberculous mycobacterial infection after clear corneal phacoemulsification cataract surgery: a report of 13 cases

PURPOSE

To review the patient profile, clinical presentation, management, and outcomes of nontuberculous mycobacterial (NTM) infection after clear corneal phacoemulsification.

METHODS

Review of consecutive cases diagnosed with NTM infection after phacoemulsification from 2004 to 2009. Demographic data, clinical characteristics, diagnosis, treatment, and outcomes were analyzed.

RESULTS

Thirteen eyes of 13 patients with mean age of 61.1 years, consisting of 7 men and 6 women were included. Twelve of 13 eyes (92%) underwent uncomplicated clear cornea phacoemulsification with posterior lens implant. Mean interval from surgery to onset of symptoms was 6.3 weeks, and time to referral ranged from 2 days to 9 months. Ten eyes (77%) presented with stromal wound abscess, whereas 3 (23%) appeared as iridocyclitis with posterior capsule plaques. Five eyes were clustered while the rest were isolated cases. All cases were culture positive for NTM. Two cases were treated medically, 3 had removal of lens implant and capsule, and 8 had penetrating keratoplasty with or without removal of lens implant, iridectomy, and/or pars plana vitrectomy. After a mean follow-up of almost 22 months, best-corrected visual acuity of 20/40 or better was achieved in half of the cases (54%). One case of recurrence was noted.

CONCLUSIONS

NTM infection should be suspected in patients presenting with corneal stromal wound abscess or iridocyclitis with posterior capsular plaques 6 to 7 weeks after phacoemulsification. Early diagnosis and treatment can lead to good outcomes, and management should include a combination of medical and surgical therapies.

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.

Antimicrobial susceptibility testing, drug resistance mechanisms, and therapy of infections with nontuberculous mycobacteria

Within the past 10 years, treatment and diagnostic guidelines for nontuberculous mycobacteria have been recommended by the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA). Moreover, the Clinical and Laboratory Standards Institute (CLSI) has published and recently (in 2011) updated recommendations including suggested antimicrobial and susceptibility breakpoints. The CLSI has also recommended the broth microdilution method as the gold standard for laboratories performing antimicrobial susceptibility testing of nontuberculous mycobacteria. This article reviews the laboratory, diagnostic, and treatment guidelines together with established and probable drug resistance mechanisms of the nontuberculous mycobacteria.

Nontuberculous mycobacterial ocular and adnexal infections

The nontuberculous (also called "atypical") mycobacteria have become increasingly important causes of systemic as well as ocular morbidity in recent decades. All ocular tissues can become infected with these organisms, particularly in patients who are predisposed following ocular trauma, surgery, use of corticosteroids, or are immunocompromised. Because of their relative resistance to available antibiotics, multidrug parenteral therapy continues to be the mainstay of treatment of more serious ocular and adnexal infections caused by nontuberculous mycobacteria (NTM). Periocular cutaneous, adnexal, and orbital NTM infections remain rare and require surgical debridement and long-term parenteral antibiotic therapy. NTM scleritis may occur after trauma or scleral buckling and can cause chronic disease that responds only to appropriate antibiotic therapy and, in some cases, surgical debridement and explant removal. NTM infectious keratitis following trauma or refractive surgical procedures is commonly confused with other infections such as Herpes simplex keratitis and requires aggressive topical therapy and possible surgical debridement, particularly in those cases occuring after laser in situ keratomileusis. Only 18 cases of endophthalmitis due to NTM have been reported. Systemic and intraocular antibiotic therapy and multiple vitrectomies may be needed in NTM endophthalmitis; the prognosis remains poor, however. Disseminated NTM choroiditis in acquired immune deficiency syndrome patients with immune reconstitution during highly active anti-retroviral therapy is a rare infection that can present as a necrotizing chorioretinitis with dense vitritis, mimicking many other entities and needs to be recognized so that timely, life-saving treatment can be administered. Regardless of which ocular tissue is infected, all NTM ocular infections present similar challenges of recognition and of therapeutic intervention. We clarify diagnosis and delineate modern, effective therapy for these conditions.

Uveitis with occult choroiditis due to Mycobacterium kansasii: limitations of interferon-gamma release assay (IGRA) tests (case report and mini-review on ocular non-tuberculous mycobacteria and IGRA cross-reactivity)

Ocular tuberculosis is difficult to diagnose but should be suspected when uveitis fails to respond to inflammation suppressive therapy. Interferon-gamma release assays (IGRAs) represent a substantial help to diagnose suspected ocular tuberculosis especially in non-endemic areas. Indocyanine green angiography (ICGA) is able to detect clinically silent choroiditis that, when associated with a positive IGRA test, should lead the clinician to suspect ocular tuberculosis, warranting specific therapy. The fact that IGRA tests can also react with some atypical strains of mycobacteria is not always known. We report here a case with resistant post-operative inflammation that presented with occult ICGA-detected choroiditis and a positive IGRA test that was most probably due to the non-tuberculous mycobacterium (NTM) Mycobacterium kansasii. A 66 year-old man presented with a resistant cystoid macular oedema (CMO) in his left eye after combined cataract and epiretinal membrane surgery. At entry, his best-corrected visual acuity (BCVA) was 0.5 for far and near OS. Intraocular inflammation measured by laser flare photometry was elevated in the left eye (54.4 ph/ms) and also in the right eye (50.9 ph/ms). Four subTenon's injections of 40 mg of triamcinolone did not produce any substantial improvement. Therefore a complete uveitis work-up was performed. Fluorescein angiography showed CMO OS and ICGA showed numerous hypofluorescent dots and fuzziness of choroidal vessels in both eyes. Among performed laboratory tests, the QuantiFERON®-TB Gold test was positive. After a pulmonological examination disclosing a right upper lobe infiltrate, the patient was started on a triple anti-tuberculous therapy. Bronchial aspirate, obtained during bronchoscopy, was Ziehl-positive and culture grew M. kansasii. Nine months later, BCVA OS increased to 1.0 and flare decreased to 40.2 ph/ms. The CMO OS resolved angiographically and did not recur with a macula still slightly thickened on OCT. Suspected ocular tuberculosis based on clinical findings and a positive IGRA test can, in rare instances, be due to atypical mycobacteria that also produce positive IGRA tests such as M. kansasii, M. szulgai, M. gordonae, M. flavescens and M. marinum. In our case failure to isolate the atypical mycobacterium would not have had negative therapeutic consequences, as M. kansasii is sensitive to the standard anti-tuberculous treatments, which is not the case with other NTMs.

What is causing the corneal ulcer? Management strategies for unresponsive corneal ulceration

Infectious keratitis represents a significant cause of ocular morbidity in the United States. The work-up and treatment of presumed infectious keratitis (PIK) has changed in the past two decades. The development of newer topical antibiotics has enabled broad-spectrum antibiotic coverage with good tissue penetration. The majority of PIK cases respond well to this strategy. The small numbers of cases that do not respond to the treatment are the cases that offer a diagnostic and therapeutic challenge. This review will describe different algorithms that can be followed for the successful management of patients with difficult or progressive PIK. These algorithms are based on scientific work and on our empirical clinical experience. The review will also present three different clinical cases of PIK that were managed according to the algorithms presented in this review.

Ocular infections caused by non-tuberculous mycobacteria: update on epidemiology and management

BACKGROUND

  To provide an update on the frequency, distribution, risk factors and in vitro susceptibility of ocular infections caused by non-tuberculous mycobacteria.

DESIGN

  Retrospective study of university clinic patients.

PARTICIPANTS

  One hundred thirty-nine patients with culture confirmed non-tuberculous mycobacteria infections seen at Bascom Palmer Eye Institute from January 1980 to July 2007.

METHODS

  Chart review of data collected included patients' demographics, risk factors, microbiological profiles and clinical outcomes.

MAIN OUTCOME MEASURES

  Frequency, distribution, risk factors and in vitro susceptibility of ocular infections caused by non-tuberculous mycobacteria.

RESULTS

  A total of 183 non-tuberculous mycobacteria isolates from 142 eyes were identified, with a fourfold increase in the number of eyes infected with non-tuberculous mycobacteria from 1980-1989 (13.4%) to 2000-2007 (56.3%). Eighty-three percent of non-tuberculous mycobacteria isolates were identified as M. abscessus/chelonae. The majority (91%) of isolates were recovered within 10 days. Common diagnoses included keratitis (36.6%), scleral buckle infections (14.8%) and socket/implant infections (14.8%). Identifiable risk factors were presence of biomaterials (63.1%), ocular surgery (24.1%) and steroid exposure (77%). The median time from diagnosis of culture positive non-tuberculous mycobacteria infection to resolution was 13 to 24 weeks. Combination therapy was used to treat 80% of infected eyes. In vitro susceptibility of non-tuberculous mycobacteria isolates were: amikacin, 81%; clarithromycin, 93%; and moxifloxacin, 21%.

CONCLUSIONS

  The incidence of ocular infections caused by non-tuberculous mycobacteria has increased within the last 8 years, with a high number of biomaterial associated infections among this group. Clinical diagnosis and microbiological confirmation of non-tuberculous mycobacteria infections remains challenging. Patient outcomes may be improved by early diagnosis, appropriate therapy and removal of biomaterials.

Comparison of the effects of fourth-generation fluoroquinolones on epithelial healing after photorefractive keratectomy

PURPOSE

To compare the effects of fluoroquinolones gatifloxacin and moxifloxacin used for antimicrobial prophylaxis after photorefractive keratectomy (PRK) on epithelial healing.

METHODS

Forty-four patients randomly received the prophylactic antibiotics gatifloxacin (Gatiflo; 0.3% gatifloxacin ophthalmic solution, Handok, Chungbuk, Korea, no preservative) in 1 eye and moxifloxacin (Vigamox; 0.5% moxifloxacin hydrochloride ophthalmic solution, Alcon Laboratories, Inc, Fort Worth, TX, no preservative) in the fellow eye after PRK. Corneal epithelium was circumferentially removed along a 7-mm zone mark. After PRK, all patients used topical antibiotics 4 times a day until the epithelium healed completely. Starting from postoperative day 1, epithelial healing times and defect sizes were recorded by slit-lamp examination and anterior segment photography. Postoperative pain and discomfort induced by the eyedrops were recorded. Additionally, therapeutic contact lenses were cultured to assess the antibacterial efficacy of fluoroquinolones.

RESULTS

The mean epithelial healing times after PRK were similar for the 2 groups: 2.97 ± 0.41 days for gatifloxacin and 2.95 ± 0.48 days for moxifloxacin (P = 0.81). There was no statistically significant difference in mean defect size on each postoperative day between the treatment groups. There was no difference in postoperative pain and discomfort. No statistically significant differences were observed between eyes treated with gatifloxacin and moxifloxacin in terms of uncorrected visual acuity or best-corrected visual acuity at 3 months postoperatively.

CONCLUSION

No significant differences were found in the effects of the preservative-free fourth-generation fluoroquinolones gatifloxacin and moxifloxacin on epithelial healing after PRK.

Atypical mycobacterium keratitis associated with penetrating keratoplasty: case report of successful therapy with topical gatifloxacin 0.3%

PURPOSE

To report successful therapy with gatifloxacin 0.3% ophthalmic solution (Zymar) in a patient with atypical mycobacterium keratitis after penetrating keratoplasty.

METHODS

A 58-year-old patient was referred for evaluation of microbial keratitis after penetrating keratoplasty.

RESULTS

Clinical examination of the patient revealed an infiltrate at the inferior graft-host junction with a satellite lesion with a mild inflammatory reaction in the anterior chamber. Microbiologic evaluation confirmed the diagnosis of atypical mycobacteria keratitis. The corneal abscess was completely eradicated with a topical course of gatifloxacin 0.3% with preservation of graft clarity and good visual acuity. Topical treatment with gatifloxacin 0.3% was continued for an additional period of 5 months.

CONCLUSION

Topical gatifloxacin 0.3% may be successfully used to treat microbial keratitis resulting from atypical mycobacteria.

Clinical significance of Mycobacterium asiaticum isolates in Queensland, Australia

Mycobacterium asiaticum was first reported as a cause of human disease in 1982, with only a few cases in the literature to date. This study aims to review the clinical significance of M. asiaticum isolates in Queensland, Australia. A retrospective review (1989 to 2008) of patients with M. asiaticum isolates was conducted. Data were collected through the Queensland TB Control Centre database. Disease was defined in accordance with the American Thoracic Society criteria. Twenty-four patients (13 female) had a positive culture of M. asiaticum, many residing around the Tropic of Capricorn. M. asiaticum was responsible for pulmonary disease (n = 2), childhood lymphadenitis (n = 1), olecranon bursitis (n = 1), 6 cases of possible pulmonary disease, and 2 possible wound infections. Chronic lung disease was a risk factor for pulmonary infection, and wounds/lacerations were a risk factor for extrapulmonary disease. Extrapulmonary disease responded to local measures. Pulmonary disease responded to ethambutol-isoniazid-rifampin plus pyrazinamide for the first 2 months in one patient, and amikacin-azithromycin-minocycline in another patient. While M. asiaticum is rare in Queensland, there appears to be an environmental niche. Although often a colonizer, it can be a cause of pulmonary and extrapulmonary disease. Treatment of pulmonary disease remains challenging. Extrapulmonary disease does not mandate specific nontuberculous mycobacterium (NTM) treatment.

Sutureless wound infection by unusual acid-fast organisms

PURPOSE

To report infection of self-sealing wounds in cataract surgery by unusual acid-fast organisms.

METHODS

Two patients who underwent phacoemulsification and developed corneal tunnel infection by acid-fast organisms were included. Both were managed with appropriate medical and surgical treatment modalities.

RESULTS

Diagnosis was facilitated in the first case by diagnostic and therapeutic lamellar keratoplasty and in the second case by the analysis of scrapings obtained from the inner lip of the tunnel. Ziehl-Neilsen staining helped diagnosis of acid-fast bacteria and implementation of adequate therapy. Nonresponse to appropriate susceptibility-guided medical therapy in the second case was controlled by timely surgical keratectomy as a peripheral patch graft.

CONCLUSIONS

Tunnel infection after phacoemulsification is a serious complication and can be caused by relatively uncommon acid-fast bacteria. Appropriate diagnostic work-up will help in the identification and institution of appropriate therapy.

Medical management approach to infectious keratitis

This section provides guidelines on medical therapy of patients with infectious keratitis. In addition to initial empirical therapy, preferred medications, once the organisms responsible are isolated, are discussed. Atypical mycobacterial keratitis following lasik is described. General guidelines for supportive therapy and follow-up, of these patients are presented. Clinical response to treatment and indications for intervention are discussed. Possible causes and approach to cases refractory to medical therapy are discussed.

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.

Bilateral deep anterior lamellar keratoplasty for the management of bilateral post-LASIK mycobacterial keratitis

A 25-year-old Vietnamese man who had bilateral simultaneous laser in situ keratomileusis (LASIK) for moderate myopia developed bilateral Mycobacterium abscessus keratitis that was treated with intensive medical therapy, flap removal, superficial keratectomy, and, following disease progression, therapeutic deep anterior lamellar keratoplasty (DALK). To our knowledge, this is the first reported case of bilateral post-LASIK mycobacterial keratitis successfully treated with DALK.

Atypical mycobacteria keratitis after laser in situ keratomileusis unresponsive to fourth-generation fluoroquinolone therapy

We report a case of post-laser in situ keratomileusis atypical mycobacteria infection unresponsive and resistant to fourth-generation fluoroquinolones, which highlights the importance of a high level of suspicion and the need for multidrug therapy for effective eradication.

Recalcitrant Post-LASIK Mycobacterium chelonae Keratitis Eradicated after the Use of Fourth-Generation Fluoroquinolone

OBJECTIVE

To report a patient with Mycobacterium chelonae keratitis after LASIK and discuss therapeutic measures.

DESIGN

Interventional case report and literature review.

INTERVENTION

A healthy, 25-year-old man presented 6 weeks after LASIK with infectious keratitis in the left eye. Scrapings were obtained from the central stromal bed after lifting the flap and inoculated on culture media.

MAIN OUTCOME MEASURES

Response to medical treatment.

RESULTS

Mycobacterium chelonae was identified from stromal bed scrapings. The protracted course of the infection necessitated surgical debridement and flap amputation with slow and suboptimal response to prolonged (14 weeks) treatment with topical amikacin 3.3%, clarithromycin 1%, and levofloxacin 0.5%. The substitution of levofloxacin 0.5% with gatifloxacin 0.3% resulted in closure of the epithelial defect within 1 week and resolution of the infiltrates in 3 weeks. The combined regimen of gatifloxacin 0.3%, amikacin 3.3%, and clarithromycin 1% was continued for a total of 4 months. The patient remains infection free 1 year after stopping all antibiotics.

CONCLUSION

Treatment of post-LASIK nontuberculous mycobacteria remains a challenge. Institution of combination therapy including fortified amikacin, clarithromycin 1%, and a fourth-generation fluoroquinolone appeared to be beneficial in this patient.

Effectiveness of fluoroquinolones against Mycobacterium abscessus in vivo

PURPOSE

To determine the effectiveness of fluoroquinolones against Mycobacterium abscessus in vivo.

METHODS

M. abscessus growth was determined quantitatively in rabbit corneas after intrastromal bacterial injection (10(4) CFU/cornea; n >or= 4 corneas per group). Eyes were treated topically with 0.3% ciprofloxacin, 0.5% levofloxacin, or 0.5% moxifloxacin by three protocols: (1) 1 drop of antibiotic applied hourly for 10 hr on day 3 postinfection (PI); (2) 1 drop applied every 2 hr for 10 hr on days 2 and 3 PI; or (3) 1 drop applied every 2 hr for 10 hr on days 1, 2, and 3 PI. Corneas were cultured 1 hr after the last topical drop. Results are expressed as the log CFU.

RESULTS

Bacteria in control group reached maximal numbers in vivo by day 3 PI (approximately 6 logs CFU/cornea). Treatment of infected eyes on day 3 with moxifloxacin or levofloxacin resulted in approximately 2.0 log decrease in CFU/cornea relative to the untreated control. Treatment on days 2 and 3 with moxifloxacin or levofloxacin resulted in approximately 3.0 and 2.5 log CFU/cornea decrease, respectively. Ciprofloxacin had no effect on bacterial load. Treatment on days 1, 2, and 3 with moxifloxacin resulted in a 5.5 log CFU decrease, whereas treatment with levofloxacin or ciprofloxacin resulted in a approximately 4.0 log CFU decrease.

CONCLUSIONS

Moxifloxacin, and to a lesser extent levofloxacin and ciprofloxacin, demonstrated significant effectiveness for reducing the number of M. abscessus in vivo, suggesting the potential usage of these agents in prevention of M. abscessus keratitis.