Effects of Fe3+ and Hemoglobin Iron on the Growth Ability of Bacillus Cereus Isolated from the Eye

Objective: To study the effects of Fe3+ and hemoglobin (Hb) iron on the ability of Bacillus cereus to grow when isolated from the eye. Methods: In this experimental study, 26 patients with post-traumatic Bacillus cereus endophthalmitis were recruited from Eye Hospital, Wenzhou Medical University and 26 strains of Bacillus cereus isolated from the eyes were obtained. The strains were divided into a light-perception (LP) group and no-light-perception (NLP) group, based on whether the patient's light perception was preserved after treatment, and the Bacillus cereus strain ATCC14579 was used as a control group. Optical density (OD) values of different strains of growth in an iron-deficient environment, different Fe3+ concentration environments, and Hb environments were measured. Data analysis was performed by independent samples t-tests. Results: The OD values of 26 strains of Bacillus cereus isolated from the eye and grown in an iron-deficient environment were weaker than the Bacillus cereus standard strain ATCC14579 (t=54.098, P<0.001). By increasing the Fe3+concentrations within a certain range (0-500 μmol/L), the OD values of the strains were gradually enhanced, and when the Fe3+ concentration was higher than 1 000 μmol/L, the OD values of the bacteria decreased. Moreover, in the environment where Fe3+ or Hb was the main iron resource, the OD values of the strains of the growth in the NLP group were stronger than that of the LP group (t=2.618, P=0.015; t=2.202, P=0.037). Conclusions: The growth of Bacillus cereus isolated from the eyes are more dependent on Fe3+, and the clinical prognosis is worse after infection with bacteria that grows faster in Fe3+ or Hb iron environments. Key words: Bacillus cereus; iron; hemoglobin iron; endophthalmitis