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Infectious Keratitis Caused by Stenotrophomonas Jun-Heon Kim, MD, Hyoung Ho Shin, MD, Jong-Suk Song, MD, and Purpose: To report a case of coinfection of the human cornea by A 59-year-old woman with a peripheral corneal ulcer in her Stenotrophomonas maltophilia and yeast.
right eye was referred to our clinic. She had undergone pterygiumexcision in the same eye 2 years previously. Two months before, Methods: A 59-year-old woman presented with a corneal ulcer. The conjunctival flap advancement surgery was performed to treat corneal lesion worsened suddenly after initial improvement with progressive scleral thinning at the previous excision site. Two days empirical antibiotic treatment. A culture revealed S. maltophilia. The before her visit, she developed sudden pain in her right eye. She keratitis rapidly progressed despite treatment with sensitivity-proven was referred for treatment under suspicion of an infectious corneal antibiotic agents. Eventually, the patient underwent therapeutic On initial ophthalmologic examination, uncorrected visual acuity was hand motion in her right eye. She had a small stromal Results: Pathology of the cornea showed yeast forms and infiltration with an overlying epithelial defect in the nasal perilimbal pseudohyphae scattered over the cornea. After surgery, the inflam- cornea, accompanied by severe uveitis. No organism was identified mation was controlled without any signs of recurrent infection.
by smear and culture of the corneal scrapings. Because 3-dayempirical treatment with topical 5% cefazolin and 1.3% tobramycin Conclusion: Coinfection of the cornea by S. maltophilia and yeast yielded no improvement, the treatment was changed to topical 5% may occur in a susceptible cornea and may not be controlled by vancomycin and 2% amikacin. After that, the corneal epithelium healed completely, and the infiltrates decreased during the next7 days. To control the severe inflammation, we started oral Key Words: coinfection, infectious keratitis, Stenotrophomonas prednisolone, 40 mg/d, with tapering, and topical 1% prednisolone acetate 4 times a day. Several days later, the inflammation was wellcontrolled, and her visual acuity had improved to 20/100. However, a toxic keratopathy was newly developed, and we changed topicalantibiotics to 0.3% ofloxacin to control the corneal toxicity. One weekafter changing eye drops, the patient complained of ocular pain and Stenotrophomonas maltophilia, which was previously des- a rapid decrement of vision. On examination,she haddense stromal ignated as Pseudomonas maltophilia and Xanthomonas suppuration with an overlying epithelial defect on more than one half maltophilia, is emerging as a multiresistant nosocomial strain.1 of the cornea and accompanied by hypopyon (Fig. 1A). We began Patients infected with S. maltophilia usually have underlying topical vancomycin, amikacin, 0.3% amphotericin B, and oral immunodeficiency, a history of long-term or multiple hos- fluconazole 200 mg/d empirically after obtaining a smear and culture pitalizations, or exposure to invasive devices and/or broad- of the scrapes from the lesion. Gram stain of the smear revealed gram-negative rods. After 48-hour cultures on blood plate agar, S. malto- philia was identified by a conventional method using the API 20 This organism has been reported as an opportunistic E system. Ceftazidime (Becton, Dickinson and Company, Sparks, MD), ocular infection that occurs mostly in patients with ocular ciprofloxacin (Oxoid Limited, Basingstoke, Hampshire, England), compromise, and it is characteristically resistant to broad- cefepime (Oxoid Limited, Basingstoke, Hampshire, England), genta- spectrum antibiotics.3 Several cases of infectious keratitis micin (Oxoid Limited, Basingstoke, Hampshire, England), levo- caused by S. maltophilia and 1 case of coinfection with floxacin (Oxoid Limited, Basingstoke, Hampshire, England), S. maltophilia and filamentous fungus have been reported.3–6 trimethoprim/sulfamethoxazole (Oxoid Limited, Basingstoke, Hamp- We report here a corneal ulcer caused by coinfection with shire, England), tetracycline (Oxoid Limited, Basingstoke, Hamp- S. maltophilia and yeast, proven by culture and histopathology.
shire, England), and piperacillin (BioMe´rieux Inc., Durham, NC)were susceptible. However, determination of the minimal inhibitoryconcentrations was not available because of the absence of referencevalues for this rare strain in our laboratory. We changed the treatmentto topical 5% ceftazidime and 0.3% ciprofloxacin on the basis of Received for publication December 21, 2005; revision received March 28, the sensitivity tests. Despite treatment with the above medications, 2006; accepted for publication April 12, 2006.
corneal melting and hypopyon progressed, and the patient com- From the Department of Ophthalmology, Korea University College of plained of persistent severe ocular pain. We changed the topical antibiotics to fortified piperacillin and started oral trimethoprim- Reprints: Hyo-Myung Kim, MD, PhD, Department of Ophthalmology, Anam sulfamethoxazole, which was also proven by sensitivity test. We Hospital, Korea University College of Medicine, 126-1 Anam-dong 1-gaSungbuk-gu, Seoul 136-705, Korea (e-mail: hyomkim@kumc.or.kr).
added again topical amphotericin B and oral fluconazole without Copyright Ó 2006 by Lippincott Williams & Wilkins further scrapings or excision of the active melting cornea. However, Cornea  Volume 25, Number 10, December 2006 Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Cornea  Volume 25, Number 10, December 2006 Infectious Keratitis Caused by S. maltophilia and Yeast FIGURE 2. Gomori methenamine silver stain of the hostcornea. Pseudohyphae and yeast forms were noted (31000).
S. maltophilia is an aerobic, nonfermenting, gram- negative bacillus that is readily isolated from water, soil,various plants, and animals. It has also emerged as animportant nosocomial opportunistic pathogen in immuno-compromised hosts, associated with debilitating illness,surgical procedures, indwelling catheters, long-term antibiotictherapy, and malignant neoplasms.7 This organism wasconsidered previously to have limited pathogenicity. However,in severely compromised patients, it may be associated withsignificant morbidity and mortality.8 Ocular infections by FIGURE 1. Slit-lamp photographs. A, Dense stromal suppura- S. maltophilia are thought to be community acquired. Underlying tion of more than one half of the cornea is noted. B, Two months ocular surface abnormalities, such as trauma, a history of after therapeutic penetrating keratoplasty, the inflammation penetrating keratoplasty, or the use of soft contact lenses, play was well controlled without any sign of the recurrent infection.
an important role in pathogenesis.3 Coinfection with S.
maltophilia and Aspergillus fumigatus has been reported.6However, infectious keratitis in which S. maltophilia and yeast the lesion continued to progress. Shortly thereafter, the patient were identified simultaneously by culture and pathology have underwent therapeutic penetrating keratoplasty.
Because the active corneal suppuration reached the limbal The exact pathogenesis of this case is unclear. The initial area, the entire cornea including the lesion was excised, and an equal- corneal ulcer had a good response to fortified vancomycin and sized donor graft was cut round using a corneoscleral scissors. Thediameter of the graft was approximately 10.5 to 11.0 mm. After amikacin. S. maltophilia or fungi were not thought to be excision of the host cornea, all inflammatory debris in the anterior causes of the initial ulcer because these organisms were not chamber was carefully removed, and the exposed intraocular tissue susceptible to those antibiotics. Prior exposure to broad-spec- was irrigated vigorously with 160 mg/mL of gentamicin in balanced trum topical antimicrobial agents or topical steroids have been salt solution. She was started on treatment with oral prednisolone consistently associated with keratitis caused by S. maltophilia 40 mg/d, oral fluconazole 200 mg/d, topical 0.3% ciprofloxacin, and or Candida species.9,10 We propose that one or both of topical 1% prednisolone acetate 4 times a day. Periodic acid-Schiff S. maltophilia and yeast might have been inoculated during the and Gomori methenamine silver staining of the excised cornea course of initial treatment. This may have occurred through showed many yeast forms and pseudohyphae scattered over the contaminated topical eye drops, during the process of corneal cornea, consistent with Candida species (Fig. 2). However, scraping, or some other route of opportunistic transmission.
identification of the strain was not attainable because the yeast didnot grow on 2-week tissue cultures. The patient continued with After improvement of the initial ulcer, we changed the topical medication, and her oral prednisolone was tapered during the topical antibiotics to ofloxacin to control the corneal toxicity.
next 2 months. After surgery, postoperative inflammation was well However, several days later, the ulcer rapidly deteriorated.
controlled without any signs of recurrent infection (Fig. 1B).
We thought that the early change of topical antibiotics, or a Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Cornea  Volume 25, Number 10, December 2006 coinfection by antimicrobial-resistant organisms such as fungi, inflammation are observed, the possibility of coinfection by might have caused this aggravation. Because the lesion rapidly these 2 organisms must be considered.
progressed, threatening the integrity of the eye, we addedtopical and systemic antifungal agents empirically without waiting for laboratory confirmation of fungi.
1. Palleroni NJ, Bradbury JF. Stenotrophomonas, a new bacterial genus for Therapeutic penetrating keratoplasty is often considered Xanthomonas maltophilia. Int J Syst Bacteriol. 1993;43:606–609.
as a means to manage infectious keratitis that is refractory 2. Denton M, Kerr KG. Microbiological and clinical aspects of infection associated with Stenotrophomonas maltophilia. Clin Microbiol Rev. 1998; to conventional medical treatment. To prevent recurrent infection, the size of the trephination must be large enough 3. Penland RL, Wilhelmus KR. Stenotrophomonas maltophilia ocular to include the entire corneal lesion. Because the perilimbal infections. Arch Ophthalmol. 1996;114:433–436.
cornea was involved in this patient, a large-diameter graft was 4. Snyder ME, Katz HR. Ciprofloxacin-resistant bacterial keratitis. Am J needed to eliminate the entire suppurative lesion. The risk of 5. Khater T, Jones DB, Wilhelmus KR. Infectious crystalline keratopathy rejection, complicated by the large-diameter graft and the caused by gram-negative bacteria. Am J Ophthalmol. 1997;124:19–23.
possibility of continued microbial proliferation, placed us in 6. Beom-Jin Cho MD, Geun-Jang Lee MD, Seung-Yeun Ha MD, et al.
a dilemma over whether to use steroids postoperatively.11 For Co-infection of the human cornea with Stenotrophomonas maltophilia that reason, before we started topical and systemic steroids, and Aspergillus fumigatus. Cornea. 2002;21:628–631.
7. Schoch PE, Cunha BA. Pseudomonas maltophilia. Infect Control Hosp a complete debridement of the inflammatory material and a vigorous irrigation with the antibiotic solution were carried 8. Morrison AJ, Hoffmann KK, Wenzel RP. Associated mortality and clinical characteristics of nosocomial Pseudomonas maltophilia in a university Infectious keratitis caused by S. maltophilia and yeast hospital. J Clin Microbiol. 1986;24:52–55.
9. Dentol M, Kerr KG. Microbiological and clinical aspects of infection has common risk factors such as a compromised cornea, associated with Stenotrophomonas maltophilia. Clin Microbiol Rev. 1998; exposure to broad-spectrum antibiotic agents, and topical immunosuppressants. Thus, coinfection of the cornea by 10. Rosa RH Jr, Miller D, Alfonso EC. The changing spectrum of fungal S. maltophilia and yeast may occur in the susceptible cornea as keratitis in South Florida. Ophthalmology. 1994;101:1005–1013.
in this case. If the progression of keratitis by S. maltophilia is 11. TichoV, Ben Sira I. Total keratoplasty. Arch Ophthalmol. 1973;90:104–106.
12. Stern GA, Buttrosski H. Use of corticosteroid in combination with not controlled using an appropriate antibiotic agent, and/or any antimicrobial drugs in the treatment of infectious corneal disease.
findings of fungal infection such as severe anterior chamber Copyright Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

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