Endogenous endophthalmitis due to Roseomonas mucosa presenting as a subretinal abscess
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Endogenous bacterial endophthalmitis is an infrequently reported entity. Although Roseomonas mucosa has been reported to cause systemic infections in immunosuppressed individuals, ocular infection due to Roseomonas has been rarely reported in literature previously.
A 74-year-old diabetic was diagnosed to have Klebsiella urinary tract infection and septicemia following which he developed ocular pain and redness. Further investigation revealed endophthalmitis with subretinal abscess and retinal detachment. The patient underwent pars plana vitrectomy with drainage of the abscess and silicone oil tamponade. The subretinal aspirate was found to contain R. mucosa confirmed on culture and PCR.
Microbiological evaluation of the subretinal purulent material revealed pink-colored colonies. Nested PCR was positive for detection of the eubacterial genome as well as for detection of the Mycobacterium tuberculosis genome (Ref)-targeting MPB64 gene. PCR examination of the subretinal pus sample ruled out M. tuberculosis and confirmed R. mucosa. The occurrence of Roseomonas endogenous endophthalmitis presenting as a subretinal abscess has not yet been reported in English literature so far to the best of our knowledge.
KeywordsRoseomonas mucosa Subretinal abscess Endogenous endophthalmitis Vitrectomy
Endogenous bacterial endophthalmitis is a rare entity with an incidence of 2 to 8% of all cases of endophthalmitis [1, 2, 3, 4]. Roseomonas mucosa is an extremely uncommon cause of endophthalmitis with scarce reports in literature. We report a subretinal abscess in an elderly diabetic male, presumably endogenous, caused by R. mucosa and its successful management.
A 74-year-old diabetic gentleman presented with redness, pain, and diminution of vision in the left eye since 2 weeks. There was no history of trauma or ocular surgery. Past history was significant for hospitalization for urinary tract infection and septicemia during which he developed the ocular symptoms. The urine and blood cultures were positive for Klebsiella species—further identification was not available. The patient had received one intravitreal injection of ceftazidime (2.25 mg/0.1 ml) in the left eye and was on oral cefotaxime (500 mg TDS) and topical moxifloxacin 0.5%, tobramycin 0.3%, homatropine hydrobromide 2%, and prednisolone acetate 1% eye drops.
Endogenous endophthalmitis is an uncommon entity , and subretinal abscess as a prominent feature is infrequently reported in literature. The most common organism reported to cause subretinal abscess is Nocardia [6, 7, 8], more so in immunocompromised patients. There are case reports of other organisms such as Pseudomonas aeruginosa , Streptococcus viridans , and Klebsiella pneumoniae  causing subretinal abscess.
The bacterial genus Roseomonas was first reported by Rihs et al.  in 1993 though the natural reservoir of the organism is unclear. Roseomonas genus is typically described as a slow-growing, pink, pigmented, aerobic, Gram-negative bacteria. This genus includes ten species, one of which is R. mucosa. This organism has been incriminated as the causative agent in catheter-related bacteremia. Literature reports have shown various instances where it has been isolated from blood, urine, and catheter samples [8, 13, 14, 15, 16, 17]. However, there is no report of R. mucosa being isolated from a subretinal abscess.
A case reported by Chen et al.  in 2008 showed that Roseomonas was the causative organism in the case of chronic postoperative endophthalmitis in an 83-year-old patient. However, in their report since the sample was not preserved, further subtyping of the species was not done. The final visual outcome was unsatisfactory.
The antibiotic sensitivity pattern of Roseomonas has been studied by Han et al.  in 2003. The choice of treatment for Roseomonas species is difficult as the susceptibility varies among different species with R. mucosa showing the highest risk of resistance. The organism has been found to be sensitive to broad-spectrum antibiotics including aminoglycosides, ciprofloxacin, imipenem, and ticarcillin but resistant to third- or fourth-generation cephalosporins such as ceftazidime [12, 14, 19].
Our case is unique in that the organism was found to be different from that predicted based on the clinical condition. PCR helped identify the organism [20, 21]. Almost complete drainage of the purulent material probably also contributed to the satisfactory outcome.
R. mucosa is a rare cause of endophthalmitis, and this is the first time the organism has been isolated from a subretinal abscess. Internal drainage of the abscess with identification of the organism and treatment with the appropriate antibiotics led to a satisfactory outcome in this patient.
The authors would like to acknowledge the support of the microbiology department in the diagnosis.
MB was the operating surgeon and handled the preparation and finalization of the manuscript. AK was the assisting surgeon and handled the collection of the data and the preparation of the manuscript. SA handled the collection of the data and the preparation of the manuscript. KLT handled the microbiological diagnosis and data collection. JB reviewed the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Ethics approval and consent to participate
Institution review board of Medical and Vision Research Foundations approved the study.
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