Supurative Meningoencephalitis and Endophthalmitis in a Calf caused by Streptococcus pyogenes

Background: Bacterial meningoencephalitis is a disease originating from the meninges and brain that presents with multiple neurological signs. In cattle, it occurs in any age group, with animals up to 90 days of age being the most affected, due to omphalophlebitis causing sepsis. To date, there are no reports of meningoencephalitis in cattle caused by Streptococcus pyogenes. Suppurative meningoencephalitis and endophthalmitis caused by S. pyogenes should be included in the differentials of neurological diseases in calves. Case: A 4-day-old male mixed-breed calf, from a beef cattle farm was submitted to necropsy, with a history of absence of colostrum consumption. The clinical signs presented were permanent lateral decubitus, respiratory difficulty and bilateral opacification of the anterior chamber of the eyes. On the aforementioned farm had a total amount of 300 cattle, 6 calves of which died by similar means. Euthanasia was performed on the calf followed by necropsy, where all organs were collected in 10% formaldehyde and subsequently histopathological evaluation was executed. Additionally, a meningeal swab and an eyeball for aerobic microbiological culture was also carried on, with the purpose to determinate the etiological agent involved. At necropsy, multiple petechiae were noted in the meninges, multiple foci of malacia that coalesced in the occipital and frontal lobe, discrete purulent exudate in the cerebral gyro of the occipital and temporal lobes, markedly xanthochromic cerebrospinal fluid, in addition to marked opacity in the anterior chamber of the eyeballs. On histopathology, the meninges revealed an accentuate diffuse infiltrate predominantly of neutrophils, with a smaller amount of macrophages, lymphocytes and plasma cells with accentuate diffuse fibrinous exudation, in addition to multifocal mild gliosis, malacia and hemorrhage in neuropil. In the anterior chamber of the eyeball was shown an accentuate diffuse neutrophilic infiltrate, associated with fibrin and cell debris, which also infiltrated the ciliary body and choroid. In the bacterial culture of meningeal and eyeball swabs, pure growth of Streptococcus pyogenes was observed. Discussion: The diagnosis of meningoencephalitis is commonly severe and frequently associated with sepsis. Bacterial meningoencephalitis is particularly prevalent in cattle aged 1 to 90 days, with an even higher incidence observed in animals aged between 4 and 12 months. In the present study, the affected animal was only 4-day-old and still in the umbilical healing phase. Typically, bacterial meningitis and encephalitis occur in early-weaned cattle, as these animals have compromised immunity and incomplete umbilical healing. The primary macroscopic finding in the brain revealed the presence of purulent exudate in the cerebral gyri, along with malacia in the occipital and frontal lobes. The histological lesions observed in this case align with those documented in the study of suppurative infectious diseases affecting the central nervous system in ruminants, conducted in the state of Rio Grande do Sul, Brazil. Differential diagnosis of suppurative meningoencephalitis caused by Streptococcus pyogenes should be performed by excluding other concurrent causes of bacterial and viral suppurative leptomeningitis. Both bacterial and viral infections are recognized as the leading etiologies of neurological diseases in ruminants.