Purpose
To report the clinical features, antibiotic sensitivities, and visual acuity outcomes of endophthalmitis caused by Enterococcus faecalis .
Study Design
Retrospective, observational case series.
Methods
A consecutive case series of patients with culture-positive endophthalmitis caused by E. faecalis between January 1, 2002, and December 31, 2012, at an academic referral center.
Results
Of 14 patients identified, clinical settings included bleb association (n = 8), occurrence after cataract surgery (n = 4), and occurrence after penetrating keratoplasty (n = 2). All isolates were vancomycin sensitive. When comparing isolates in the current study with isolates from 1990 through 2001, the minimal inhibitory concentration required to inhibit 90% of isolates increased for ciprofloxacin (4 μg/mL from 1 μg/mL), erythromycin (256 μg/mL from 4 μg/mL), and penicillin (8 μg/mL from 4 μg/mL), indicating higher levels of resistance. The minimal inhibitory concentration required to inhibit 90% of isolates remained the same for vancomycin (2 μg/mL) and linezolid (2 μg/mL). Presenting visual acuity ranged from hand movements to no light perception. Initial treatment strategies were vitreous tap and intravitreal antibiotic injection (n = 12) and pars plana vitrectomy with intravitreal antibiotic injection (n = 2). Visual acuity outcomes were 20/400 or worse in 13 (93%) of 14 patients.
Conclusions
Although all isolates were sensitive to vancomycin and linezolid, higher minimal inhibitory concentration required to inhibit 90% of isolates in the current study, compared with isolates from 1990 through 2001, occurred with ciprofloxacin, erythromycin, and penicillin. Despite prompt treatment, most patients had poor outcomes.
E nterococcus faecalis is a gram-positive bacterium that is part of the normal human gastrointestinal track flora. Enterococci are the second most common cause of nosocomial catheter-associated infections of the bloodstream and urinary tract and of skin and soft-tissue infections. E. faecalis , a relatively rare cause of endophthalmitis, accounted for approximately 1% of culture-positive acute endophthalmitis cases occurring after cataract surgery in the Endophthalmitis Vitrectomy Study. The most common clinical settings for E. faecalis endophthalmitis include acute onset after cataract surgery, delayed-onset bleb-related cases, and trauma. In previous reports, patients with endophthalmitis caused by E. faecalis have worse visual outcomes than coagulase-negative Staphylococcus species, the most common cause of postoperative endophthalmitis overall.
Enterococci have high rates of resistance to many commonly used antibiotics, including clindamycin, cephalosporins, and aminoglycosides. Additionally, the incidence of vancomycin-resistant enterococci infections during hospitalizations rose from 4.68 per 100 000 in 2000 to 9.48 per 100 000 in 2006. There are higher rates of vancomycin resistance among E. faecium species compared with E. faecalis . The only cases reported in the literature of endophthalmitis resulting from E. faecalis resistant to vancomycin originated in Asia.
A previous study from 1990 to 2001 from our institution reported clinical settings, antibiotic sensitivities, and treatment outcomes for endophthalmitis caused by E. faecalis. There have been more recent studies of E. faecalis endophthalmitis from Asia. However, there is variation in prevalence and antibiotic resistance patterns of E. faecalis from different geographical areas. Additionally, the cause of vancomycin resistance differs among different geographic regions; in the United States, it is attributed to antibiotic use in the hospital setting, whereas in Europe and Asia, it is attributed to antibiotic use for livestock. Prior reports from the United States and other geographic areas have not analyzed the minimum inhibitory concentration for 90% of isolates (MIC 90 ) of E. faecalis for different antibiotics, which is an indicator of the level of antibiotic resistance.
The purpose of this study was to provide an update on the clinical settings, antibiotic sensitivities, and visual acuity (VA) outcomes in a more recent series of culture-proven endophthalmitis caused by E. faecalis in the United States. This is the first study (based on a PubMed search) to compare MIC 90 data between periods for cases of endophthalmitis caused by E. faecalis .
Methods
The study protocol for a retrospective review of medical and microbiology records for all patients treated at Bascom Palmer Eye Institute with vitreous and aqueous fluid culture-proven endophthalmitis caused by E. faecalis species between January 1, 2002, and December 31, 2012, was approved by the Institutional Review Board of the University of Miami Miller School of Medicine Medical Sciences Subcommittee for the Protection of Human Subjects. Isolates were identified using standard microbiologic procedures. Shifting trends in in vitro MIC 90 (in micrograms per milliliter) were analyzed using the E test (Biomeriuex, Raleigh, North Carolina, USA). The treatment strategies were determined by the individual treating physicians and did not follow a standardized protocol.
Results
Patient Demographics and Clinical Settings
Endophthalmitis caused by E. faecalis was identified in 14 eyes of 14 patients. The demographics and clinical settings for each patient are summarized in Table 1 . Of the 14 patients, 8 (57%) were men and 8 (57%) were right eyes. Mean age at presentation was 74 years (range, 54 to 86 years). Clinical settings included 8 bleb-associated cases (57%), 4 cases occurring after cataract surgery (29%), and 2 cases occurring after penetrating keratoplasty (14%). One of the bleb-associated cases was an inadvertent bleb created during extracapsular cataract extraction surgery. One of the cases occurring after cataract surgery was the result of a dehisced extracapsular cataract extraction wound. One of the cases occurring after penetrating keratoplasty was combined with pars plana vitrectomy (PPV), scleral-fixated intraocular lens, and Baerveldt glaucoma implant tube repositioning surgeries.
| Patient No. | Age (y) | Eye | Gender | Clinical Setting | Time after Surgery |
|---|---|---|---|---|---|
| 1 | 79 | Left | Male | Bleb association | 10 y |
| 2 | 68 | Right | Female | Bleb association | Unknown |
| 3 | 67 | Left | Female | Bleb association | 17 mos |
| 4 | 78 | Right | Male | Bleb association | 2 mos |
| 5 | 77 | Right | Male | Bleb association | 12 y |
| 6 | 54 | Left | Female | Bleb association | 8 y |
| 7 | 80 | Left | Female | Bleb association (Seidel +) | 30 y |
| 8 | 86 | Right | Male | Bleb association a | 16 y |
| 9 | 82 | Right | Female | After cataract surgery (ECCE) b | 31 y |
| 10 | 78 | Left | Female | After cataract surgery (phacoemulsification) | 6 d |
| 11 | 82 | Right | Male | After cataract surgery (phacoemulsification) | 2 d |
| 12 | 64 | Right | Male | After cataract surgery (phacoemulsification) c | 14 d |
| 13 | 73 | Left | Female | After PKP | 8 d |
| 14 | 71 | Right | Female | After PKP/PPV/scleral-fixated IOL/BGI revision | 8 d |
b Dehisced complicated ECCE wound.
c Symptoms for 1 week, diagnosis delayed because of outside hospitalization.
Microbiology and Antibiotic Resistance
E. faecalis was identified in vitreous samples in 13 (93%) of 14 patients and in the anterior chamber of 1 (7%) patient. All cultures were monomicrobial. The antibiotic susceptibilities and MIC 90 of E. isolates from the current study are summarized and compared with isolates from 1990 to 2001 in Table 2 . All E. faecalis isolates tested were susceptible to vancomycin (13 of 13 [100%]) and linezolid (13 of 13 [100%]). There were low rates of resistance to ciprofloxacin (2 of 13 [15%]), high-level gentamicin (minimum inhibitory concentration [MIC], >500 mg/L; 2 of 14 [14%]), and penicillin (1 of 10 [10%]). There were higher rates of resistance to erythromycin among isolates from 2002 through 2012 (7 of 10 [70%]) compared with 1990 through 2001 (3 of 8 [38%]). Similarly, there were higher rates of resistance to tetracycline among isolates from 2002 through 2012 (11 of 14 [79%]) compared with 1990 through 2001 (8 of 11 [73%]). The MIC 90 for isolates from 2002 through 2012 and from 1990 through 2001 remained the same for vancomycin (2 μg/mL), linezolid (2 μg/mL), and tetracycline (16 μg/mL). The MIC 90 from 2002 through 2012 increased 2-fold for penicillin, 4-fold for ciprofloxacin, and 64-fold for erythromycin.
| Antibiotic | 2002 to 2012 | 1990 to 2001 | ||||
|---|---|---|---|---|---|---|
| No. of Isolates Tested | Resistant Isolates (%) | MIC 90 | No. of Isolates Tested | Resistant Isolates (%) | MIC 90 | |
| Erythromycin | 10 | 7 (70) | 256 | 8 | 3 (38) | 4 |
| Ciprofloxacin | 13 | 2 (15) | 4 | 14 | 1 (7) | 1 |
| Gentamicin a | 14 | 2 (14) | NA | 29 | 5 (17) | NA |
| Linezolid | 13 | 0 (0) | 2 | 29 | 0 (0) | 2 |
| Penicillin | 10 | 1 (10) | 8 | 21 | 2 (10) | 4 |
| Quinupristin/dalfopristin | 7 | 7 (100) | 32 | 0 | NA | NA |
| Tetracycline | 14 | 11 (79) | 16 | 11 | 8 (73) | 16 |
| Vancomycin | 13 | 0 (0) | 2 | 23 | 0 (0) | 2 |
Clinical Presentation and Management
The initial and subsequent clinical management of patients are summarized in Table 3 . The presenting VA was light perception (LP) in 10 (71%) of 14 patients, hand movements in 3 (21%) patients, and no light perception in 1 (7%) patient. Pain was present in 13 (93%) of 14 patients. The mean intraocular pressure was 34 mm Hg (range, 11 to 56 mm Hg). A hypopyon was present in 13 (93%) of 14 patients. A view of the posterior pole was unobtainable in all of the patients because of severe anterior segment inflammation and media opacities.
| No. | Preinfection VA | Initial VA | IOP (mm Hg) | Initial Treatment | Initial Intravitreal Injection(s) | Additional Treatment (Days after Initial Treatment) | Additional Intravitreal Injection(s) | Last VA | Follow-up Time |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 20/30 | LP | 28 | PPV | VANC + CTZ + DEX | None | None | HM | 7 y |
| 2 | 20/30 | LP | UK | T + I | VANC + CTZ | None | None | NLP | 4.5 y |
| 3 | 20/200 | LP | 11 | T + I | VANC + CTZ + DEX | PPV (9) | VANC + CTZ + DEX | LP | 8 y |
| 4 | UK | LP | 42 | T + I | VANC + CTZ + DEX | None | None | LP | 6 d |
| 5 | 20/40 | HM | 51 | T + I | VANC + CTZ + DEX | T + I (71) a , PPV + PPL + capsulectomy (74) a | VANC + CTZ + DEX | HM | 13 mos |
| 6 | 20/100 | LP | 36 | T + I | VANC + CTZ + DEX | Enucleation (8) | None | NLP | 8 mos |
| 7 | CF | LP | 32 | PPV | VANC + CTZ + DEX | None | None | NLP | 4.5 y |
| 8 | 20/30 | LP | 40 | T + I | VANC + CTZ + DEX | None | None | NLP | 13 mos |
| 9 | 20/20 | LP | 44 | T + I | VANC + CTZ + DEX | PPV + ACIOL removal (1) | VANC + CTZ + DEX | LP | 6 mos |
| 10 | 20/40 | NLP | 44 | T + I | VANC + CTZ + DEX | T + I (1), enucleation (6) | VANC + DEX | NLP | 12 mos |
| 11 | UK | HM | 13 | T + I | VANC + CTZ | T + I (1) | VANC + AMI | 20/25 | 4.5 y |
| 12 | 20/100 | LP | 22 | T + I | VANC + CTZ + DEX | PPV (9) | VANC + CTZ + DEX | HM | 13 mos |
| 13 | CF | HM | 56 | T + I | VANC + CTZ + DEX | None | None | 6/200 | 3 y |
| 14 | 4/200 | LP | 13 | T + I | VANC + CTZ | None | None | LP | 18 mos |
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