Abiotrophia defective, classified as nutritionally variant streptococci, are normal flora of the oral cavity, gut, and urogenital tracts of humans[4]. Additionally, it can also be acquired from the ocular surface, which rarely leads to conjunctivitis and keratitis[5].] Endocarditis was mostly reported caused by Abiotrophia defectiva[6, 7]. However, there have been very few reports of Abiotrophia defectiva causing endophthalmitis until submission in the literature, including 5 cases after conventional cataract surgery[4, 8–10], 3 cases of keratopath[5, 11, 12], 2 cases after trabeculectomy[13, 14], and 1 case after intravitreal injection of dexamethasone[15]. Different from all the published case reports, for the rapid progress of the endophthalmitis by Abiotrophia defective, the severe vitritis hindering the view of the fundus, we firstly observed retinal vasculitis in the very early stage of this disease.
The improper handling of samples, transportation delays, and their particular requirements for growth may have contributed to the negative findings and few reports. In our case, he had positive vitreous sample cultures on day 5, compared to Debarshi’s on day 2 and Ming-Han’s on day 17[13, 14]. It is speculated that L-cysteine and L-alanine in the vitreous could enable the growth of Abiotrophia defectiva[14].
Notably, Abiotrophia defectiva is a rare cause of endophthalmitis. In our case, the fundus photography showed that the peripheral retinal blood vessels were white sheathing and a large number of scattered hemorrhagic sites. The cause of rapid fundus lesions may be correlated with the binding ability and virulence of Abiotrophia defectiva. On the one hand, Abiotrophia defectiva has a strong binding force to fibronectin and produces a large number of extracellular polysaccharides, which can adhere to fibronectin at the junction between the vitreous and retina nerve fibers. On the other hand, it may be antibody and antigen complex deposition in vessel walls, causing vascular damage and inflammatory response.[4, 16].
In the case of endophthalmitis, the key elements of the treatment plan are the initial vitreous tap and intravitreal injection of antibiotics (the current recommendation is vancomycin combined with ceftazidime). In all published case reports of Abiotrophia defectiva endophthalmitis, Namdari, Mustafi, and Yousef et al found that the patients treated with prompt vitrectomy had significantly better visual outcomes[8, 14, 15]. Han and Madalina et al reported that timely vitreous tap and multiple vitreous injections resulted in good visual outcomes for patients[4, 13]. Our patient underwent urgent anterior chamber irrigation, vitreous tap, and intravitreal injection, but the vitritis progressed. Then, we did a vitrectomy immediately on the first day after intravitreal injection, and with accurate antigenic therapy, the patient achieved a better visual outcome.