Clinical and microbiological features of bacteremia with Streptococcus equi

Streptococcus zooepidemicus Meningitis in an HIV-Positive Horse Breeder Patient: A Case Study and Literature Review

Streptococcus equi subsp. zooepidemicus is a rare etiologic agent of bacterial meningitis in humans. The disease is a zoonotic infection and is transmitted through close contact with domestic animals, mainly horses. Only 37 cases of Streptococcus zooepidemicus meningitis have been reported in the literature until July 2023. The aim of this study is to present a rare clinical case of S. zooepidemicus-related meningitis in a human immunodeficiency virus (HIV)-positive patient and analyze the literature. We present a 23-year-old horse breeder patient with advanced immunosuppression due to acquired immunodeficiency syndrome (AIDS) and S. zooepidemicus meningitis, admitted at the Clinic of Infectious Diseases, St. George University Hospital, Plovdiv. The course of meningitis was severe since the beginning, with significant cerebral edema, disturbances in consciousness, persistent fever, and the development of complications against the background of AIDS-related conditions. S. zooepidemicus was microbiologically detected from cerebrospinal fluid culture. After prolonged treatment and a long hospital stay, the patient's condition improved, and eventually he was discharged and recovered from the acute neuroinfection. Although extremely rare, S. zooepidemicus should be considered in patients with clinical and laboratory evidence of bacterial meningitis who have contact with animals, especially horses, other domestic animals, and their dairy products, as well as in immunocompromised patients. To the best of our knowledge, the current clinical case is the first report of S. zooepidemicus-related meningitis in a patient with HIV/AIDS.

A 56-Year-Old Woman with Chronic Hepatitis C Liver Disease and Meningitis due to Streptococcus equi subsp. Zooepidemicus

Streptococcus equi subsp. zooepidemicus (S. equi subsp. zooepidemicus), which carries the Lancefield group C antigen, is an uncommon human pathogen. It is considered an opportunistic commensal of the equine upper respiratory tract and causes invasive infections in immunocompromised hosts, following close contact to infected horses. Meningitis caused by S. equi subsp. zooepidemicus is a rare infectious disease with high rates of complications. We present the case of a 56-year-old female with acutely altered mental status following three days of fever and vomiting. For several months, she was taking care of horses. The most relevant preexisting illnesses were chronic hepatitis C infection and traumatic paraplegia due to spinal cord injury 30 years ago. Laboratory evaluation on admission revealed leukocytosis, hyponatremia, and elevated C-reactive protein. Cerebral CT scan showed diffuse cerebral edema. Whereas cerebrospinal fluid real-time PCR assay for common pathogens was negative, cultures showed S. equi subsp. zooepidemicus. She recovered fully after intravenous administration of ceftriaxone for four weeks. This is one of only few reported cases of S. equi subsp. zooepidemicus meningitis and the first case in chronic hepatitis C infection. Our case supports the necessity for extended microbiological examination especially in immunocompromised patients if PCR examination for common pathogens is negative.

Zoonotic infection and clonal dissemination of Streptococcus equi subspecies zooepidemicus sequence type 194 isolated from humans in Thailand

Streptococcus equi subsp. zooepidemicus (SEZ) is a zoonotic pathogen associated with diseases in a wide range of animals as well as in humans. SEZ sequence type (ST) 194 strains have been associated with outbreaks in China, the USA, and Canada and have caused high mortality in pigs. Nevertheless, human infection by this ST has never been reported. This study conducted a retrospective analysis of 18 SEZ strains from human patients in Thailand during 2005-2020. The study revealed clonal dissemination of ST194 with the identical pulsotype in human patients throughout Thailand. Clinical manifestation was mainly septicemia (61.1%), while 72.2% had a history of eating raw pork products. There were six fatal cases (33.3%). Antimicrobial susceptibility testing revealed that all strains were susceptible to penicillin, ampicillin, cefotaxime, erythromycin, levofloxacin, clindamycin, chloramphenicol, tetracycline and vancomycin. Virulence-associated genes, including bifA, szM, szP, sdzD, spaZ, and fszF, were present in all tested strains. Some representative genes in four pathogenicity islands found in the swine outbreak SEZ-ATCC35246 (ST194) strain were detected in these SEZ strains. Whole-genome sequencing analysis of three representative SEZs in this study revealed no acquired antimicrobial-resistant genes and they contained the same virulence factors. The single-nucleotide polymorphism phylogenetic tree demonstrated that the current strains were clustered with swine ST194 strains. The results should be highlighted as a public health concern, especially to those who may directly or indirectly have contact with livestock or companion animals or have consumed raw meat products as risk factors for infections with SEZ.

Infrarenal aortic reconstruction using autologous femoral vein for a mycotic aneurysm caused by Streptococcus equi

A common source of infection in equine, Streptococcus equi, is an uncommon pathogen in humans, rarely identified as the cause for mycotic aortic aneurysms. Typically associated with consumption of unpasteurized milk or contact with horses, S. equi can result in severe bacteremia, endocarditis and meningitis. We describe the presentation and successful management of a 69-year-old retired equestrian who underwent infrarenal aortic resection and reconstruction using autologous right femoral vein for a S. equi mycotic aneurysm.

Streptococcus equi subspecies zooepidemicus Meningitis, Septicemia, and Brain Infarcts in a Costa Rican Infant

Streptococcus equi, an equine commensal bacterium, is a rare etiology of septicemia and meningoencephalitis in humans and is extremely infrequent in children. Scarce literature has been published about its clinical presentation, treatment and outcomes in infants. Here, we describe a case of S. equi subsp. zooepidemicus septicemia and meningoencephalitis in a five-month-old Costa Rican infant that was confirmed by peripheral blood and cerebrospinal fluid (CSF) cultures in a regional hospital of the Pacific coast of Costa Rica who developed multiple ischemic cerebral infarcts secondary to infectious vasculitis, a subdural empyema and serious neurological sequelae. We also reviewed the literature on S. equi meningitis in infants under one year of age. This is the first reported case in our country, the fourth reported in infants under one year of age and the second describing multiple cerebral infarcts and subdural empyema in an infant.

Molecular Evidence of a Broad Range of Pathogenic Bacteria in Ctenocephalides spp.: Should We Re-Examine the Role of Fleas in the Transmission of Pathogens?

The internal microbiome of common cat and dog fleas was studied for DNA evidence of pathogenic bacteria. Fleas were grouped in pools by parasitized animal. DNA was extracted and investigated with 16S metagenomics for medically relevant (MR) bacteria, based on the definitions of the International Statistical Classification of Diseases and Related Health Problems (WHO). The MR bacterial species totaled 40, were found in 60% of flea-pools (N = 100), and included Acinetobacterbaumannii, Bacteroidesfragilis, Clostridiumperfringens, Enterococcusfaecalis, E. mundtii, Fusobacteriumnucleatum, Haemophilusaegyptius, Kingellakingae, Klebsiellapneumoniae, Leptotrichiabuccalis, L. hofstadii, Moraxellalacunata, Pasteurellamultocida, Propionibacteriumacnes, P. propionicum, Proteusmirabilis, Pseudomonasaeruginosa, Rickettsiaaustralis, R. hoogstraalii, Salmonellaenterica, and various Bartonella, Staphylococcus, and Streptococcus species. B. henselae (p = 0.004) and B. clarridgeiae (p = 0.006) occurred more frequently in fleas from cats, whereas Rickettsiahoogstraalii (p = 0.031) and Propionibacteriumacnes (p = 0.029) had a preference in fleas from stray animals. Most of the discovered MR species can form biofilm, and human exposure may theoretically occur through the flea-host interface. The fitness of these pathogenic bacteria to cause infection and the potential role of fleas in the transmission of a broad range of diseases should be further investigated.

Impending rupture of mycotic aortic aneurysm infected with Streptococcus equi subspecies zooepidemicus

Streptococcus equi subspecies zooepidemicus is a beta-haemolytic, group C streptococcal bacterium. Although it is an opportunistic pathogen commonly found in horses, transmission to human can lead to severe infections. Here, we present a patient with S. equi subspecies zooepidemicus bacteraemia and consequent development of mycotic aneurysms.

Mycotic Abdominal Aortic and Iliac Aneurysm Caused by Streptococcus equi Subspecies zooepidemicus Bacteremia

This report describes a case of a taxidermist who presented with sepsis and excruciating back pain a few weeks after contact with a deceased horse. Streptococcus equi subspecies zooepidemicus (SESZ) was isolated from patient's blood and two isolated mycotic aneurysms were found. The first was located in the distal abdominal aorta and the second in the right common iliac artery. Treatment consisted of penicillin administration for 6 weeks and surgical debridement of the infected tissue combined with autologous vein reconstruction. The patient was infection-free without complaints 1 year after discharge and the venous reconstruction was patent. Reports in literature of bacteremia with SESZ leading to the development of mycotic aneurysms are very scarce and show that prognosis is generally unfavorable.

Prominent Binding of Human and Equine Fibrinogen to Streptococcus equi subsp. zooepidemicus Is Mediated by Specific SzM Types and Is a Distinct Phenotype of Zoonotic Isolates

Streptococcus equi subsp. zooepidemicus is an important pathogen in horses that causes severe diseases such as pneumonia and abortion. Furthermore, it is a zoonotic agent, and contact with horses is a known risk factor. In this study, we investigated the working hypothesis that the zoonotic potential varies among S. equi subsp. zooepidemicus strains in association with differences in M-like protein-mediated binding of host plasma proteins. We demonstrate via in-frame deletion mutagenesis of two different S. equi subsp. zooepidemicus strains that the M-like protein SzM is crucial for the binding of fibrinogen to the bacterial surface and for survival in equine and human blood. S. equi subsp. zooepidemicus isolates of equine and human origins were compared with regard to SzM sequences and binding of equine and human fibrinogens. The N-terminal 216 amino acids of the mature SzM were found to exhibit a high degree of diversity, but the majority of human isolates grouped in three distinct SzM clusters. Plasma protein absorption assays and flow cytometry analysis revealed that pronounced binding of human fibrinogen is a common phenotype of human S. equi subsp. zooepidemicus isolates but much less so in equine S. equi subsp. zooepidemicus isolates. Furthermore, binding of human fibrinogen is associated with specific SzM types. These results suggest that SzM-mediated binding of human fibrinogen is an important virulence mechanism of zoonotic S. equi subsp. zooepidemicus isolates.

Streptococcus equi subsp. zooepidemicus and 'Neighbourhood syndrome' -extra-orbitocranial rhinosinusitis with reversible sudden loss of vision- a case report

Background

Rhinosinusitis is a common condition which may present with complications commonly involving the orbit and the intracranial space. Loss of vision in the absence of clinical or radiological signs of involvement of the orbit and intracranium is rare and carries a high morbidity rate. Streptococcus equi subspecies zooepidemicus is not a well-documented cause of paranasal sinus infection.

Case presentation

We present a case of a 16 year old female patient who had unilateral loss of vision with signs of retrobulbar optic neuritis and no other neurological signs. We isolated an unusual organism- Streptococcus equi subspecies zooepidemicus from the maxillary sinus. Emergency endoscopic sinus surgery and antibiotic treatment resulted in complete reversal of the loss of vision.

Conclusion

The presence of paranasal sinus disease in association with loss of vision even in the absence of a clear link between the two should be treated as an emergency with surgical drainage and or appropriate antibiotic therapy. In patients presenting with suspected inflammatory orbital involvement, imaging of the orbit and paranasal sinuses should be considered early.

Sepsis, Endocarditis, and Purulent Arthritis due to a Rare Zoonotic Infection with Streptococcus equi Subspecies zooepidemicus

Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) is mostly known as an opportunistic pathogen found in horses and as a rare human zoonosis. An 82-year-old male, who had daily contact with horses, was admitted in a septic condition. The patient presented with dyspnea, hemoptysis, impaired general condition, and severe pain in a swollen left shoulder. Synovial fluid from the affected joint and blood cultures showed growth of S. equi subsp. zooepidemicus. Transesophageal echocardiography showed a vegetation on the aortic valve consistent with endocarditis. Arthroscopic revision revealed synovitis and erosion of the rotator cuff. Technetium-99m scintigraphy showed intense increased activity in the left shoulder, suspicious of osteitis. The infection was treated with intravenous antibiotics over a period of five weeks, followed by oral antibiotics for another two months. The patient recovered without permanent sequelae.