The Treatment Process and Clinical Analysis of 2 Cases of Enterococcus Faecalis Infection Following Cataract Surgery

Abstract

Purpose:

To report the clinical diagnosis and treatment of 2 cases of endophthalmitis caused by Enterococcus faecalis following cataract surgery.

Methods:

Two elderly patients (aged 69 and 87 years) who developed postoperative endophthalmitis after cataract extraction underwent emergency vitrectomy, anterior chamber irrigation, and intravitreal vancomycin injection. Aqueous humor and vitreous fluid samples were collected for bacterial culture and antimicrobial susceptibility testing.

Results:

Both patients required repeat irrigation due to persistent vitreous opacity. Bacterial culture of vitreous fluid confirmed Enterococcus faecalis (Group D) infection, which was sensitive to vancomycin, penicillin G, levofloxacin, and tigecycline. Post-treatment visual acuity improved to 0.5 (Case 1 at 3 months) and 0.1 (Case 2 at 1 month), respectively.

Conclusion:

These 2 cases suggest that early vitrectomy combined with intravitreal vancomycin may be an effective treatment for postoperative Enterococcus faecalis endophthalmitis. However, due to the small sample size, these findings should be interpreted with caution. Vitreous fluid culture appears more reliable than aqueous humor culture for pathogen identification.

Introduction

Cataract is a common ophthalmic condition, particularly in the elderly population. It is characterized by lens opacity leading to visual impairment ¹ With the global aging population, cataract surgery has become 1 of the most frequently performed ophthalmic procedures. However, postoperative complications, especially intraocular infections, remain a concern.

Studies have shown that the incidence of intraocular infection after cataract surgery is relatively low, but the risk is significantly higher in patients with underlying conditions such as diabetes and hypertension. ² In recent years, advances in surgical techniques and the widespread use of antibiotics have reduced the rate of postoperative infections. Nevertheless, vigilance is still required, particularly in elderly patients during the early postoperative period. ³

Enterococcus faecalis is a common clinical intestinal pathogen, but its role in intraocular infections remains underexplored. This paper reports 2 clinical cases of intraocular infection caused by Enterococcus faecalis, emphasizing the importance of postoperative monitoring and rapid intervention. A detailed analysis of these cases serves as a reference for clinical diagnosis and management and offers data to improve prevention and control strategies for intraocular infections in elderly patients.

Case Reports

Case 1

A 69-year-old man was admitted on May 8, 2020, with a chief complaint of “blurred vision in both eyes for over one year.” Ocular examination revealed a best-corrected visual acuity (BCVA) of 0.06 in the right eye and 0.25 in the left eye. No conjunctival congestion was observed in either eye. The corneas were transparent, the anterior chambers were clear, and the pupils were round with a diameter of 3.0 mm. Lens cortical opacity was noted, and the vitreous body was slightly turbid. Fundus examination showed clear optic disk margins and normal retinas. Intraocular pressure was 18 mmHg in the right eye and 16 mmHg in the left eye. Ocular B-ultrasound revealed mild vitreous opacities in both eyes.

The patient had a history of hypertension, which was well-controlled with regular medication. He also had a 1-year history of diabetes without pharmacological intervention, with a fasting blood glucose of 8.12 mmol/l and glycated hemoglobin (HbA1c) of 8.9%. The patient had a long-standing history of hepatitis B “small triple positive.”

On the second morning after admission, phacoemulsification aspiration and intraocular lens implantation for cataract in the right eye were performed. The operation was uneventful. On the first postoperative day, visual acuity in the right eye was 0.5, and no abnormalities were found. The patient was subsequently discharged.

On the same day (May 10, 2020) at 10:00 PM, the patient was readmitted because of “progressive visual acuity loss in the right eye for over two hours.” Physical examination showed that vision in the right eye was reduced to finger counting. Conjunctival hyperemia, mild corneal edema, variable anterior chamber depth, and a 1 mm hypopyon were observed. The pupil was round (approximately 3.0 mm in diameter), and an exudative membrane was seen in the pupillary area. The intraocular lens was correctly positioned, the fundus was unclear, and intraocular pressure was normal. Ocular B-ultrasound showed significant turbidity in the anterior segment of the right eye compared with preoperative findings. Intraocular infection was suspected.

Emergency vitrectomy of the right eye, anterior chamber irrigation, and intravitreal injection (vancomycin) were performed. Before the operation, 0.1 ml of aqueous humor and 0.1 ml of vitreous fluid were obtained via puncture for bacterial culture and drug susceptibility testing.

During the operation, vitreous opacity was observed, and a small amount of white strip-like flocculent material was found in the anterior vitreous and removed. Triamcinolone acetonide staining was performed, followed by complete vitreous detachment. White vascular sheaths were visible in the lower and upper peripheral retina, with no hemorrhage or detachment. After vitrectomy, retinal photocoagulation was applied to the area of the white sheaths (258 spots). The posterior capsule was incised, creating a hole of approximately 2.0 mm. A perfusion solution containing vancomycin at a concentration of 0.06 mg/ml was injected into the vitreous cavity. The anterior chamber and lens capsule were rinsed with vancomycin-containing solution. Then, 0.1 ml of vancomycin (containing 1 mg) was injected into the vitreous cavity. The scleral puncture site and conjunctiva were sutured with 8/0 absorbable sutures. Postoperatively, 2.5 g of cefuroxime sodium, 0.6 g of clindamycin, and 5 mg of dexamethasone were administered intravenously.

On the first day after vitrectomy, the patient’s right eye visual acuity was finger counting at 20 cm. The right eyelid was slightly swollen, the conjunctiva was congested, the cornea was edematous, and the anterior chamber was cloudy. The pupil was round and pharmacologically dilated to 6.0 mm. The intraocular lens was properly positioned, the vitreous cavity was slightly turbid, the fundus was blurred, and intraocular pressure was 15 mmHg. Gatifloxacin eye drops were administered as an anti-inflammatory measure, carteolol eye drops were used to reduce intraocular pressure, and atropine ophthalmic gel was applied for pupillary dilation. The patient’s condition remained stable on the second day.

On the third morning after vitrectomy, the patient’s right eye had hand motion vision. The anterior segment response had improved, but vitreous opacity worsened. Culture of the puncture fluid indicated the growth of Gram-positive cocci. A repeat irrigation of the right anterior chamber and vitreous cavity was performed on May 13, 2020. During the procedure, exudative membranes were observed in the pupillary area and on the lens capsule, along with a small amount of white flocculent material in the vitreous cavity. These were removed. Local and systemic anti-inflammatory treatment continued postoperatively.

On the first day following the repeat procedure, the patient’s right eye visual acuity was 0.12. The conjunctiva was congested, the cornea was slightly edematous, and the anterior chamber was mildly hazy. The pupil was round and pharmacologically dilated to 6.0 mm. The intraocular lens was properly positioned, the vitreous cavity was slightly hazy, and intraocular pressure was 15 mmHg. No bacterial growth was observed in the aqueous humor culture. The vitreous fluid culture and drug susceptibility test confirmed Enterococcus faecalis (Group D) infection, sensitive to vancomycin, penicillin G, levofloxacin, and tigecycline.

On the second and third days, the patient’s condition remained stable, and vision improved. On the fourth day, visual acuity in the right eye was 0.25. The conjunctiva showed mild congestion, the cornea was transparent, the anterior chamber was clear, and intraocular pressure was 16 mmHg. OCT of the right macula showed no obvious abnormalities.

The patient was discharged on May 18, 2020. Three months postoperatively, visual acuity in the right eye was 0.5.

Case Two

An 87-year-old woman was admitted on November 24, 2024, with a chief complaint of “marked deterioration of vision in the left eye over one day.” Ocular examination revealed a visual acuity of 0.12 in the right eye and light perception in the left eye. The left eye showed mixed conjunctival congestion, ciliary tenderness (+), mild corneal edema, hypopyon, aqueous humor turbidity, and massive exudation in the pupillary area. The remaining intraocular structures could not be visualized. The right eye showed no abnormalities. Intraocular pressure was normal. Ocular B-ultrasound showed vitreous opacity in the left eye.

The patient had a history of hypertension, which was well-managed with medication. Three days before admission, she had undergone phacoemulsification and intraocular lens implantation for senile cataract in the left eye at a local county hospital. The patient’s family reported that left eye visual acuity was 0.2 on the first postoperative day.

The patient was diagnosed with endophthalmitis of the left eye upon admission. Emergency vitrectomy, anterior chamber irrigation, and intravitreal injection (vancomycin) were performed. Before the operation, 0.1 ml of aqueous humor and 0.1 ml of vitreous fluid were aspirated for bacterial culture and drug susceptibility testing. During the procedure, a large amount of purulent opacity was observed within the vitreous body and was subsequently removed. Triamcinolone acetonide staining was performed to ensure complete vitreous resection. A perfusion solution containing vancomycin (0.06 mg/ml) was injected into the vitreous cavity. The anterior chamber and lens capsule were rinsed with vancomycin-containing solution. Then, 0.1 ml of vancomycin (containing 1 mg) was injected into the vitreous cavity. Postoperatively, 2.5 g of cefuroxime sodium, 0.6 g of clindamycin, and 5 mg of dexamethasone were administered intravenously.

On the first postoperative day, the patient had light perception in the left eye, with conjunctival congestion, mild corneal edema, and anterior chamber opacity. The pupil was round and pharmacologically dilated to 5.0 mm. The intraocular lens was properly positioned, the vitreous cavity was slightly turbid, and intraocular pressure was 18 mmHg. On the second day, the anterior segment response improved, but vitreous opacity worsened. Culture of the puncture fluid showed growth of Gram-positive cocci. A repeat irrigation was performed on November 26, 2024. During the procedure, exudative membranes and a small amount of white flocculent material were removed. Local and systemic anti-inflammatory treatment continued.

On the first day following the repeat procedure, the patient’s left eye had hand motion vision. The conjunctiva was congested, the cornea was slightly edematous, the anterior chamber was mildly turbid, and intraocular pressure was 20 mmHg. Aqueous humor culture showed no bacterial growth. Vitreous fluid culture confirmed Enterococcus faecalis (Group D) infection, sensitive to vancomycin, penicillin G, levofloxacin, and tigecycline. The patient’s condition remained stable over the following days.

On the fifth day after vitrectomy, visual acuity in the left eye was 0.04. The conjunctiva showed mild congestion, the cornea was transparent, the anterior chamber was clear, and intraocular pressure was Tn. OCT of the left macula showed no obvious abnormalities. The patient was discharged on December 1, 2024. One month postoperatively, visual acuity in the left eye was 0.1.

Discussion

Post-cataract surgery infectious endophthalmitis is an acute purulent inflammation of the uvea, retina, and even corneosclera caused by pathogenic microorganisms.^4,5 This condition typically presents acutely and progresses rapidly. According to Wang et al, risk factors for post-cataract endophthalmitis include elderly males, rural residence, and systemic immunosuppressive conditions such as diabetes. ⁶

In Case 1, the patient was an elderly male living in a rural area with a 1-year history of uncontrolled diabetes (fasting blood glucose ~8.0 mmol/l). Case 2 involved an elderly female also residing in a rural area. These observations suggest that a detailed medical history should be obtained before cataract surgery, and if predisposing factors are present, infection prevention should be strengthened. Whenever possible, underlying diseases should be treated before surgery is scheduled.

According to national and international reports, the proportion of Enterococcus faecalis infection after cataract surgery has increased with the widespread use of antibiotics^7,8 In this article, the causative pathogen was Enterococcus faecalis, a facultative anaerobic Gram-positive lactic acid bacterium. It has strong environmental adaptability and exhibits resistance to various antibiotics, including tetracycline, kanamycin, and gentamicin. Its growth conditions are not stringent.

The Chinese Expert Consensus on the Prevention and Treatment of Infectious Endophthalmitis after Cataract Extraction recommends that pathogenic bacteria be identified at the time of diagnosis. If anaerobic bacterial infection is suspected, the ideal specimens to collect include anterior aqueous humor (0.1-0.2 ml) and vitreous humor (0.1-0.2 ml).^6,9

In our cases, no bacterial growth was observed in postoperative aqueous humor cultures. However, vitreous fluid cultures confirmed Enterococcus faecalis (Group D) infection, suggesting that the vitreous cavity may provide a more favorable environment for bacterial persistence. According to relevant reports, ¹⁰ the detection rate of bacteria in aqueous humor is lower than that in the vitreous, although the difference is not statistically significant. Nevertheless, culturing both aqueous humor and vitreous specimens is of great value, and simultaneous bacterial culture and drug susceptibility testing are recommended.

Regarding treatment, both patients underwent vitrectomy, anterior chamber irrigation, and intravitreal vancomycin injection, combined with systemic antibiotic therapy. Dosing references were based on relevant literature^11,12 When the initial intravitreal injection did not adequately control the infection, repeat anterior chamber and vitreous irrigation was performed. Postoperatively, both patients showed improved vision and clinical status.^13,14

Compared with the study by Kim et al, in which Enterococcus faecalis accounted for less than 5% of post-cataract endophthalmitis cases ⁷ our 2 cases suggest a potentially higher prevalence in elderly patients with comorbidities. This discrepancy may reflect regional differences in antibiotic use or patient demographics. Furthermore, unlike previous reports that emphasized aqueous humor culture alone, ⁹ our findings highlight the diagnostic value of vitreous fluid culture.

According to Barry et al, active vitrectomy should be performed for endophthalmitis after cataract surgery. This approach is beneficial for removing the cloudy vitreous body, eliminating most bacteria and toxins, and avoiding or alleviating tractional retinal detachment caused by vitreous organization. ¹⁵

Conclusion

The 2 cases presented in this article provide important insights into the postoperative management of elderly patients. The patients’ medical histories, including diabetes and hypertension, appeared to impact their postoperative recovery and infection risk. This suggests that individualized factors should be considered when formulating treatment plans.

These cases suggest that anti-infection strategies, including the use of vancomycin, may be effective in the management of postoperative infections and improving patient outcomes. However, due to the small sample size, these findings should be interpreted with caution. The treatment regimen described in this article differed slightly from traditional methods documented in the literature, with adjustments tailored to the patients’ specific conditions.

Moreover, rapid identification of early symptoms of postoperative infection, timely eye examinations, and imaging assessments appeared to facilitate subsequent treatment and prevent serious consequences resulting from delayed diagnosis. These cases suggest that regular follow-up may play an important role in the timely detection of potential complications.

Nevertheless, this case study has limitations, including individual patient variability and the limited generalizability of the results to broader populations. Although the treatment demonstrated favorable efficacy, the small sample size restricts the generalizability of the findings.

Future research should focus on large-scale clinical trials to verify the effectiveness of individualized anti-infection strategies in patients with diverse backgrounds. Additionally, enhanced monitoring and management of postoperative complications—especially in elderly patients—are needed. Further exploration of the impact of underlying diseases such as diabetes and hypertension on postoperative recovery is warranted (Figure 1).

Figure 1.

Treatment timeline of 2 cases of postoperative enterococcus faecalis endophthalmitis.