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Update on acute and chronic endophthalmitis

1999; Elsevier BV; Volume: 106; Issue: 12 Linguagem: Inglês

10.1016/s0161-6420(99)90521-3

1549-4713

Thomas A. Ciulla,

Ocular Diseases and Behçet’s Syndrome

In this issue, Aldave et al present an important retrospective review of 25 cases of culture-proven Propionibacterium acnes endophthalmitis after cataract extraction and review the earlier literature. Postoperative endophthalmitis is a potentially devastating complication that mandates prompt recognition and appropriate treatment. To facilitate proper initial management and therapy, endophthalmitis can be divided into acute and chronic forms. Acute bacterial postoperative endophthalmitis has been extensively studied in a randomized prospective clinical trial, the Endophthalmitis Vitrectomy Study (EVS).1Endophthalmitis Vitrectomy Study GroupResults of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis.Arch Ophthalmol. 1995; 113: 1479-1496Crossref PubMed Scopus (1283) Google Scholar Patients with acute postoperative endophthalmitis present with pain, photophobia, floaters, reduced vision, an inflamed anterior segment including a variable hypopyon, and vitreitis. In the EVS, the median time to presentation to an EVS study center was on postoperative day 6, and typical organisms included coagulase-negative staphylococci (46.9%), other gram-positive organisms (15.5%), and, much less commonly, gram-negative organisms (4.1%).1Endophthalmitis Vitrectomy Study GroupResults of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis.Arch Ophthalmol. 1995; 113: 1479-1496Crossref PubMed Scopus (1283) Google Scholar Until the EVS, the utility of pars plana vitrectomy to potentially decrease the bacterial and toxin load, facilitate intravitreal antibiotic distribution, and clear the media was unknown, as was the need to administer systemic antibiotics in addition to intravitreal antibiotics. To address these issues, the EVS investigators enrolled 420 patients with endophthalmitis who presented within 6 weeks of cataract extraction or secondary intraocular lens placement and randomized them in a 2 by 2 factorial design to pars plana vitrectomy versus vitreous tap and also to intravenous ceftazidime plus amikacin versus no systemic antibiotics. All patients received intravitreal vancomycin plus amikacin. The study showed that intravenous antibiotics did not improve outcome.1Endophthalmitis Vitrectomy Study GroupResults of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis.Arch Ophthalmol. 1995; 113: 1479-1496Crossref PubMed Scopus (1283) Google Scholar In addition, in patients with visual acuity better than light perception (74% of the patients in the study) pars plana vitrectomy did not improve outcome.1Endophthalmitis Vitrectomy Study GroupResults of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis.Arch Ophthalmol. 1995; 113: 1479-1496Crossref PubMed Scopus (1283) Google Scholar The EVS generated some controversy. First, patients randomized to vitreous tap could undergo either a needle-mediated vitreous aspiration or automated vitrectomy of up to 0.3 ml fluid. In a series of letters-to-the-editor, some clinicians expressed concern that the potential for a minivitrectomy could have favorably confounded the vitreous tap arm of the study (131 of 201 patients in the tap group underwent vitrectomy tap). Second, some clinicians felt that the choice of systemic antibiotics was suboptimal and that a systemic regimen preferably including vancomycin could have demonstrated a beneficial effect. This drug penetrates the blood-retinal barrier2Meredith T.A. Aguilar H.E. Shaarawy A. et al.Vancomycin levels in the vitreous cavity after intravenous administration.Am J Ophthalmol. 1995; 119: 774-778Abstract Full Text PDF PubMed Scopus (86) Google Scholar and covers staphylococcal species, which cause a significant percentage of cases of acute postoperative endophthalmitis, better than amikacin. Despite these controversies, the EVS provides very useful guidelines for the management of acute postoperative endophthalmitis. In particular, cataract surgeons should not hesitate to perform aqueous as well as vitreous taps and inject antibiotics into eyes of patients who present with signs of acute postoperative endophthalmitis and with visual acuity better than light perception if immediate posterior segment consultation is not available. Cataract surgeons are facile with aqueous taps using a 30-gauge needle at the temporal limbus. Similarly, a 27-gauge needle inserted 3.5 mm posterior to the temporal limbus is used to aspirate 0.1–0.3 ml vitreous; the procedure is repeated with a new needle if vitreous obstructs the needle. Vancomycin (1.0 mg/0.1 ml) plus amikacin (0.2–0.4 mg/0.1 ml) or vancomycin (1.0 mg/0.1 ml) plus ceftazidime (2.0 mg/0.1 ml) can be injected at the pars plana after vitreous tap; the latter regimen may be preferable because aminoglycosides can cause retinal necrosis at high levels in cases of dilution error. Patients with visual acuity of light perception or worse should be promptly referred for consideration of pars plana vitrectomy. Some clinicians also inject dexamethasone at 0.4 mg/0.1 ml to minimize the morbidity of severe ocular inflammation. Some clinicians initiate a course of oral ofloxacin (400 mg twice daily) as initial systemic therapy or following a brief course of intravenous therapy because oral ofloxacin is readily available, is well tolerated, has broad coverage (including slightly better coverage for gram-positive organism than ciprofloxacin), and achieves reasonable intravitreal levels.3Cekic O. Batman C. Yasar U. et al.Penetration of ofloxacin in human aqueous and vitreous humors following oral and topical administration.Retina. 1998; 18: 521-525Crossref PubMed Scopus (30) Google Scholar The EVS should not be directly extrapolated to traumatic or postfiltration surgery endophthalmitis because the responsible organisms in these cases differ. Post-traumatic endophthalmitis can involve Bacillus cereus, anaerobes or, rarely, fungus, in addition to host flora such as coagulase-negative staphylococci. B. cereus endophthalmitis is fulminant. Bleb-associated endophthalmitis denotes a rapidly progressive ocular infection with involvement of the vitreous, which usually develops months or years after glaucoma filtering surgery. Streptococcus species such as S. pneumoniae and gram-negative organisms such as Hemophilus influenzae are most frequently isolated from late-onset endophthalmitis associated with filtering blebs.4Mandelbaum S. Forster R.K. Gelender H. Culbertson W. Late onset endophthalmitis associated with filtering blebs.Ophthalmology. 1985; 92: 964-972Abstract Full Text PDF PubMed Scopus (176) Google Scholar In both post-trauma and bleb-related endophthalmitis, systemic treatment with intravenous vancomycin and ceftazidime merits consideration because of the fulminant nature of these infections. For intravitreal therapy, a regimen of intravitreal antibiotics similar to that used in the EVS is prudent. The role of pars plana vitrectomy in these cases is unclear, but given the very aggressive nature of these infections, should be considered. In contrast to acute postoperative endophthalmitis, chronic postoperative endophthalmitis presents insidiously, and accurate diagnosis supersedes urgent treatment; patients can be referred nonemergently to a posterior segment specialist. Endophthalmitis due to P. acnes, a pleomorphic gram-positive anaerobic bacillus, is particularly difficult to diagnose and treat. Patients typically present with mild, topical steroid-responsive, anterior uveitis several months to several years after cataract surgery. The classic sign, which may not be present, is a white plaque in the capsular bag, representing collections of organisms that typically adhere to the capsule. Sequestration in the capsular bag is thought to be responsible for recurrences of infection after patients undergo conventional treatment with pars plana vitrectomy and intravitreal antibiotic injection. In addition, this fastidious organism is difficult to culture. Optimal treatment includes intravitreal vancomycin (1 mg/0.1 ml) plus consideration of pars plana vitrectomy with or without capsulectomy with or without intraocular lens (IOL) exchange or removal. Aldave and others, in this issue, compare the efficacy of these various treatment regimens as well as final visual acuities in 25 patients. The authors demonstrate that approximately half of patients with P. acnes endophthalmitis were successfully treated initially with nonsurgical or limited surgical interventions. All patients treated with total capsulectomy and IOL exchange or removal, as initial or ultimate treatment, were cured of infection. In a similar recent study of 36 patients, Clark and others5Clark L. Kaiser P. Flynn H. et al.Treatment strategies and visual acuity outcomes in chronic postoperative Propionibacterium acnes endophthalmitis.Ophthalmology. 1999; 106: 1665-1670Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar noted treatment failure in all 12 patients treated with antibiotic injection only; in 5 of 10 patients treated with antibiotic injection and pars plana vitrectomy; and in 2 of 14 patients treated with antibiotic injection and pars plana vitrectomy plus partial capsulectomy. All patients who underwent subsequent antibiotic injection, pars plana vitrectomy, total capsulectomy, and IOL exchange or removal were cured of infection.5Clark L. Kaiser P. Flynn H. et al.Treatment strategies and visual acuity outcomes in chronic postoperative Propionibacterium acnes endophthalmitis.Ophthalmology. 1999; 106: 1665-1670Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar In both of these retrospective studies, final visual acuity did not significantly differ between the treatment groups. Regarding the decision to pursue these progressively more aggressive therapies, the limited numbers of cases in such retrospective studies limit their value, but Aldave and others aptly state, “As the choice of initial therapy does not appear to influence the final visual acuity, the decision instead centers on the significance to the patient and physician of the risk for recurrence versus the risks of the therapeutic interventions themselves.” Other organisms to consider in chronic postoperative endophthalmitis include coagulase-negative staphylococci and, rarely, fungi (filamentous fungi or “molds,” such as Aspergillus and, only very rarely, yeasts, such as Candida). Although coagulase-negative staphylococcal endophthalmitis typically presents within 2 weeks, it may present indolently, mimicking P. acnes endophthalmitis. Like P. acnes, this organism is responsive to intravitreal vancomycin. Unlike P. acnes, however, capsulectomy or IOL exchange is typically not necessary. Also potentially mimicking P. acnes endophthalmitis, filamentous fungal endophthalmitis is typically associated with a latent period of 1 to several months and low-grade pain. Patients can present with granulomatous keratic precipitates and yellow-white lesions with fluffy borders in the posterior pole as well as retinitis, manifested by whitish exudate along vessels, and pars planitis. Vitreous smears for fungi require special staining. Although Gram staining may be negative in fungal endophthalmitis, Calcofluor-white staining is often positive. Treatment involves pars plana vitrectomy with intravitreal amphotericin B (5–10 μl/0.1 ml). The value of systemic amphotericin is unknown for filamentous fungal endophthalmitis. In rare cases of postoperative yeast (Candida) endophthalmitis, fluconazole at high dose (400–600 mg orally per day) is beneficial.6Luttrull J.K. Wan W.L. Kubak B.M. et al.Treatment of ocular fungal infections with oral fluconazole.Am J Ophthalmol. 1995; 119: 477-481PubMed Google Scholar Clinicians may wish to consider biopsy or excision of the capsule for culture in pseudophakic patients who have strong clinical evidence of refractory endophthalmitis but negative previous vitreous cultures because there are reports noting that fungi tend to adhere to various intraocular tissues.7Pflugfelder S. Flynn Jr, H.W. Zwickey T.A. et al.Exogenous fungal endophthalmitis.Ophthalmology. 1988; 95: 19-30Abstract Full Text PDF PubMed Scopus (184) Google Scholar In summary, acute and chronic postoperative endophthalmitis differ significantly with regard to causative organisms, presentation, and treatment. A careful history and examination can allow the clinician to rapidly diagnose and categorize endophthalmitis to facilitate proper initial management and to minimize the morbidity from this devastating disorder.