March 2008

 

OPHTHALMOLOGY NEWS

 

Vexing endophthalmitis cases


by Matt Young EyeWorld Contributing Editor

 

 

Vulnerabilities still exist even through treatment advances

Same eye after resolution of the endophthalmitis

Vitreous with active endophthalmitis showing vitreous abscess Source: Thomas A. Hanscom, M.D.

A recent outbreak of endophthalmitis shows how vulnerable the eye continues to be to this infection in spite of the latest advances in treatment. For one, eyes in a recent study were affected by Enterobacter amnigenus Biogroup II, “a gram-negative bacillus which, to the best of our knowledge, has never been reported in the eye,” wrote lead study author Korah Sanita, D.O., Department of Ophthalmology, Christian Medical College, India. The study was published in the November/December 2007 issue of the Indian Journal of Ophthalmology. The organism was resistant even to gentamicin (various manufacturers), which is typically effective against gram-negative pathogens like Pseudomonas that can be devastating to the eye. Further, vitrectomy could not be performed in the patients because severe stromal edema obscured the surgical view. Ultimately, physicians were able to save 17 of 19 globes with other treatments, but the outbreak certainly suggests that endophthalmitis remains visually taxing and difficult to treat.

A devastating case series

Nineteen eyes were affected by the outbreak. They were among a surgical camp of 63 patients who had undergone cataract surgery. A few patients from day two of the camp and almost all from day three suffered from the endophthalmitis outbreak. Patients presented with decreased vision, lid edema, and gross corneal edema with severe exudative reaction. Fifteen of the eyes were affected by hypopyon.

Patients’ antibiotic regimen at the time included topical gentamicin and oral ciprofloxacin (Ciloxan, Alcon, Fort Worth, Texas). After a diagnostic vitreous tap, 18 patients were given intravitreal injections of vancomycin (1.0 mg / 0.1 ml saline) and ceftazidime (Tazicef, 2.25 mg / 0.1 ml saline, GlaxoSmithKline, Philadelphia, Pa.). One patient refused surgery. Patients also were given oral and topical ciprofloxacin as well as dexamethasone–chloramphenicol.

Further susceptibility testing showed the organism to be resistant to penicillin, vancomycin, gentamicin (various manufacturers), norfloxacin (Chibroxin), ciprofloxacin, tetracycline, chloramphenicol (Chloroptic, Allergan, Irvine, Calif.), lomifloxacin, ofloxacin (Ocuflox, Allergan), and tobramycin (Tobrex, Alcon). It was sensitive to ceftazidime, cefotaxime (Claforan, Sanofi Aventis, Paris), imipenem, and meropenem. Intravitreal injections were repeated every 48 hours, and when the susceptibility report was complete, patients were continued on intravitreal ceftazadime only. Three vitreous samples showed gram-negative organisms appeared smear and extensive growth upon culture. The organism was found to be Enterobacter amnigenus Biogroup II.

“Patients with poorer vision at presentation did worse than those with better vision,” Dr. Sanita reported. “Four patients developed corneal infiltrates, which eventually resolved in two patients. The other two resulted in autoevisceration, one a newly detected diabetic who allowed only two intravitreal injections, and the other who refused any surgical intervention.”

Of course, treatment of these cases could not follow the typical endophthalmitis treatment regimen because of the inability to perform vitrectomy. “Vitreous tap for smear and culture, followed by immediate intravitreal administration of broad-spectrum antibiotics and, a vitrectomy if indicated is the current standard of care,” Dr. Sanita wrote. “Although most patients in this series qualified for immediate vitrectomy according to the Endophthalmitis Vitrectomy Study protocol, this was deferred due to severe stromal edema obscuring the view.”

Notably, even without vitrectomy, five of 19 patients regained 20/200 vision or better.

What happened?

The study author noted that a serious breach of asceptic procedure had to have occurred for this pathogen to cause what it did. “The causative organism, Enterobacter amnigenus isolated in our series, is an environmental pathogen and normally results in infection only if inoculated in high doses,” Dr. Sanita wrote. “This implies a serious breach of aseptic measures during surgery in these patients.” Unfortunately, the outbreak could not be thoroughly investigated because containers of fluids used were discarded at the conclusion of surgeries. Unopened containers of viscoelastic and other fluids were analyzed but proved sterile. “In another series of endophthalmitis caused by Enterobacter species, inadvertent use of unsterilized swabs was found to be responsible,” Dr. Sanita wrote. Enterobacter is a common pathogenic genus, said Mark Packer, M.D., clinical associate professor, Casey Eye Institute, Oregon Health & Science University, Portland.

Although this particular type of Enterobacter pathogen may be a new subspecies, there are a number of gram-negative bacteria that are described as causing infections in other locations and also in the eye, Dr. Packer said. Hence, although it may be somewhat worrisome that a new pathogen has emerged as causing endophthalmitis, bacteria have been known to cause other health issues before affecting the eye. “These bacteria are around, although the vast majority of endophthalmitis is gram-positive,” Dr. Packer said. They arise from normal flora around the eyelashes. That said, gram-negative bacteria are much more devastating to the eye than gram-positive pathogens, Dr. Packer said. So it’s no small matter that a new gram-negative pathogen has been shown to affect the eye and cause endophthalmitis. “It’s a nasty contaminant for someone to get an eye infection from,” Dr. Packer said.

Editors’ note: Dr. Packer has no financial interests related to his comments. Dr. Sanita has no financial interests related to this study.

Contact Information

Packer: 541-687-2110, mpacker@finemd.com

Sanita: sanviji@cmcvellore.ac.in

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