Endogenous endophthalmitis caused by group B streptococcus; case reports and review of 35 reported cases
Group B streptococcus (GBS), a gram-positive coccus that occasionally causes neonatal sepsis or invasive infection in the elderly, has been considered a rare cause of endogenous bacterial endophthalmitis (EBE). However, the number of invasive GBS infections is increasing, particularly in elderly patients with underlying conditions such as diabetes mellitus (DM), cardiovascular disease and cancer. We report 6 cases of EBE caused by GBS and review the literature. Methods: Retrospective case
... spective case series and literature review Results: In the current case series, 6 eyes of 6 patients developed EBE caused by GBS. The average age was 73.5 years. The focus of infection included the urinary tract, cellulitis, arthritis, peritonitis, catheter-associated infection and endocarditis. Four patients had DM. While all 6 strains were sensitive to β-lactams (penicillins and cephems), 4 strains were resistant to levofloxacin (no data for 1 isolate). Each case was treated with the systemic antibiotic to which the individual strain was sensitive. All cases showed poor visual acuity at presentation (decimal visual acuity: less than 0.03). Vitrectomy with intravitreal antibiotics injection was performed in 4 cases. Visual acuity recovered in 4 cases and did not recover in 2 cases, even after vitrectomy. The literature review of 53 eyes of 41 patients revealed that 60% of eyes finally lost all vision, and death occurred in 2 cases. Initial visual acuity of less than counting fingers was associated with a final outcome of lost vision. Of 41 patients, 13 (32%) had DM as an underlying medical condition. The most common extraocular infection site was endocarditis (37%). Conclusions: DM is common in patients with EBE caused by GBS. While the 4 cases in the current report had a relatively good visual acuity outcome, despite poor initial visual acuity, the literature review indicated that EBE caused by GBS is generally a severe condition with a poor prognosis. The current study also indicates the importance of considering the possibility of endocarditis on encountering EBE caused by GBS. Background Endogenous bacterial endophthalmitis (EBE), a complication of systemic blood-stream infection, is a rare but dangerous threat to vision. Studies from different geographical regions have obtained different results on causative organisms in EBE: East Asian reports found that gram-negative organisms, especially Klebsiella pneumoniae, were the leading cause of EBE, while Western reports 4 found that gram-positive organisms such as Staphylococcus aureus and Streptococcus pneumonia were more frequent    . Group B streptococcus (GBS; Streptococcus agalactiae), a gram-positive coccus that occasionally causes neonatal sepsis or invasive infection in the elderly, has been considered a rare cause of EBE, especially in East Asia. However, the number of invasive GBS infections is increasing, particularly in elderly patients with underlying conditions such as diabetes mellitus (DM), cardiovascular disease and cancer . In the last 15 years, our affiliated institutions (Tohoku University Hospital and Gifu University Hospital), located in Japan, have seen at least 6 cases of EBE caused by GBS in elderly patients. Moreover, an online search revealed 10 more cases in Japan [9-18]. Thus, at least 35 cases of EBE caused by GBS in adults have been reported in English or Japanese [2, 9-33]. Although a variety of microorganisms cause EBE, we consider that GBS is one of the most important. Here, we examine the clinical characteristics of EBE caused by GBS, describe 6 cases we observed, and review relevant recent literature, including a comparison of East Asian and Western cases. Methods Patients We retrospectively reviewed the records of 6 eyes of 6 patients with EBE caused by GBS, all of whom were observed at Tohoku University Hospital or Gifu University Hospital between December 2003 and September 2016. The diagnosis of EBE caused by GBS was based on positive results from culture testing of blood or ocular samples (either the aqueous humor or vitreous body) obtained from patients with iritis and vitritis during ophthalmic examination. Patients with a potential exogenous cause of infection, such as trauma, recent ocular surgery or corneal ulcer, were excluded. Clinical histories, including underlying medical conditions, initial symptoms, culture testing, infection foci, treatment and final visual acuity outcome were examined. Database searches were performed with Medline for articles in English and Google Scholar for articles in Japanese for the period ending in June 2019. Each search query included the terms "Group B streptococcus", "streptococcus agalactiae" and "endogenous endophthalmitis". In Google Scholar, these Japanese equivalents for these terms were used. These searches identified 47 eyes of 35 patients with EBE caused by GBS (Medline: 36 eyes of 5 29 patients in 18 English articles, Google Scholar: 11 eyes of 6 patients in 6 Japanese articles). Thus, combined with the 6 eyes of 6 patients observed directly, this study retrospectively reviewed the records of 53 eyes of 41 patients. Microbiological studies At Tohoku University Hospital, isolated colonies on 5% sheep blood agar plates were evaluated with matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) using the VITEK MS ver. 3.0 (bioMérieux, Marcy L'Étoile, France); this revealed that the colonies comprised Streptococcus agalactiae. At Gifu University Hospital, identification of GBS was performed with Gram staining, a catalase reaction, examination of colony morphology, hemolysis with a blood agar plate, and an examination for the Lancefield group B antigen. Susceptibility testing for antibiotics was performed with the microdilution method at both participating institutions. The MicroScan WalkAway 96 plus System (Beckman Coulter Inc., Brea, CA, USA) with a MICrofast7J panel was used at Tohoku University Hospital and the RAISUS system (Nissui Pharmaceutical Co., Ltd., Tokyo, Japan) with an NKMP1 plate was used at Gifu University Hospital. All results were interpreted according to the Clinical and Laboratory Standards Institute standard method. Statistical analysis Fisher's exact test was used to compare binary data. P values <0.05 were considered statistically significant. Results A. Observational case series A clinical summary of the 6 cases observed at our clinics is shown in Table 1 . One patient was male, and the other 5 were female. The average age was 73.5 (range: 65-80) years. Every patient had unilateral endophthalmitis (3 left eyes and 3 right eyes). Four patients had DM. Three patients reported visual disturbance as the initial symptom, while the other three initially reported systemic symptoms, such as fatigue, anorexia and algor. The specialties of the initially consulted doctors were MY was a major contributor to the drafting of the manuscript. SY and TN reviewed and edited the manuscript. TN, MK, and TS acquired the clinical data. KM, TO, KN, and HK were responsible for the interpretation of results. All authors read and approved the final manuscript.