Human infection with Streptococcus zooepidemicus (Lancefield group C): three case reports

Streptococcus equi subspecies zooepidemicus: an emergent cause of meningoencephalitis in Northeastern Brazil

This study describes an outbreak of Streptococcus equi subspecies zooepidemicus infections that caused meningoencephalitis and bacteremia related to unpasteurized milk consumption in northeastern Brazil. Epidemiological investigations and a brief literature review were conducted. Strains with possible neurotropism had not been identified in Brazil before these cases; however, in 2023, another case of meningoencephalitis caused by Streptococcus equi sp. zooepidemicus was described, revealing the need to maintain surveillance and highlighting that these neurotropic strains continue to circulate in the environment.

Streptococcus zooepidemicus in dogs: Exploring a canine pathogen through multilocus sequence typing

Streptococcus equi. subsp. zooepidemicus (S. zooepidemicus) associated diseases in dogs have emerged as a significant concern over recent decades. S. zooepidemicus occurs sporadically in dog populations globally, with increased prevalence in shelters/kennels. This study used multilocus sequence typing (MLST) of 149 independent canine S. zooepidemicus isolates to assess associations between sequence type and breed, country of origin, disease severity, sampling type, year, and behaviour within an outbreak. No clear associations for breed, country, sampling type and year were determined in this study. ST-10 and 123 strains were present within all disease categories, from no clinical signs to severe disease. Assessment of S. zooepidemicus infection in 3 UK outbreaks at the same location found ST-10, 18, 123 strains, and a ST-173 strain in a US outbreak, were associated with haemorrhagic pneumonia and persisted in kennelled populations over time. The ST-173 clonal complex has been noted to have severe virulence capabilities in dogs and other species. S. zooepidemicus seems to thrive in environments with a high risk of transmissibility, overcrowding, stress and naïve populations, particularly for those in shelters/kennels. MLST alone cannot determine the virulence phenotype of S. zooepidemicus in dogs. However, a level of conservancy and diversity within ST allelic loci aids the opportunity to cause severe disease in dogs. Thus, further research into whole genome sequencing and characterising the virulence factors of S. zooepidemicus is warranted in dogs.

Twenty-year Follow-up of Patients With Epidemic Glomerulonephritis due to Streptococcus zooepidemicus in Brazil

Introduction

Post-streptococcal glomerulonephritis (PSGN) has a good prognosis in children, but few studies have evaluated the long-term renal outcomes in adults with PSGN.

Methods

In a follow-up study, 47 predominantly adult patients with PSGN due to group C Streptococcus zooepidemicus were reassessed 20 years after an outbreak in Nova Serrana, Brazil. We evaluated clinical characteristics, renal outcomes, and the trajectory of the estimated glomerular filtration rate (eGFR) by the creatinine-based chronic kidney disease-epidemiology collaboration equation from 5 follow-up assessments. Logistic regression and mixed-effects regression were used in the analysis.

Results

After 20 years, the participants’ mean age was 56.6±15.1 years. Thirty-four (72%) patients had hypertension, 21 (44.7%) had eGFR <60 ml/min per 1.73 m², 8 of 43 (18.6%) had urine protein-to-creatinine ratio >150 mg/g, and 25 (53%) had CKD (low eGFR and/or increased proteinuria). Increasing age was associated with CKD (odds ratio: 1.07; 95% confidence interval [CI]: 1.02–1.13; P = 0.011) in multivariate analysis. The mean eGFR decline in the last 11 years of follow-up was −3.2 ml/min per 1.73 m² per year (95% CI: −3.7 to −2.7). Older age at baseline (coefficient −1.05 ml/min per 1.73 m² per year; 95% CI −1.28 to −0.81; P < 0.001), and hypertension 5 years after the outbreak (coefficient −7.78 ml/min/1.73 m²; 95% CI −14.67 to −0.78; P = 0.027) were associated with lower eGFR during the whole study period.

Conclusion

There was a marked worsening of renal function and a high prevalence of CKD and hypertension after 20 years of PSGN outbreak. Long-term follow-up is warranted after PSGN, especially among older patients.

Mycotic Abdominal Aortic Aneurysm Caused by Streptococcus equi

Streptococcus equi is a bacterium common in equine species and an uncommon pathogen in humans. Reported human infections can be severe and include meningitis, septic arthritis, and endocarditis. We report the case of a 64-year-old male who S. equi with several months of constitutional symptoms, back pain, and abdominal pain. Imaging demonstrated a large abdominal aortic aneurysm with a contained retroperitoneal rupture, with cultures from the aneurysm and blood cultures both positive for S. equi. The patient was successfully treated with open repair and placement of a Dacron graft and intravenous antibiotics and will remain on lifelong antibiotic prophylaxis.

Artritis séptica por Streptococcus equi: reporte de un caso y revisión de la literatura

En humanos las infecciones producidas por Streptococcus equi son de rara ocurrencia, tienen una amplia variedad de formas de presentación, incluyendo com­promiso articular, el cual ha sido pocas veces descrito en humanos y aún menos en pacientes inmunocompetentes. En este artículo se presenta un caso de artritis séptica por S. equi que ocurrió por una exposición ocupacional en un paciente inmunocompetente y la revisión de la literatura relacionada.

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.

Highly pathogenic beta-hemolytic streptococcal infections in cats from an institutionalized hoarding facility and a multi-species comparison

OBJECTIVES

Two hundred and thirty-four cats removed from an institutionalized hoarding facility (IHF) demonstrated severe, atypical pyogenic infections. The objective of this study was to document the various syndromes and determine the etiology of the infections.

METHODS

All cats were evaluated initially after removal from the IHF and on a daily basis for at least 15 months. Samples were collected and sent for culture/susceptibility and histopathology to commercial laboratories or stored at -20(o)C. PCR was performed using universal bacterial primers to amplify the 16S-23S rRNA intergenic spacer region. PCR products were sequenced to determine the identity of the bacteria.

RESULTS

Multiple pyogenic syndromes were documented, including abscesses of the paws and carpal/tarsal regions in 82 cats, acute rhinitis with profuse purulent nasal discharge in 68 cats and cervical lymphadenitis with abscessation unassociated with any wounding in 51 cats. Many cats exhibited septic arthritis with total joint destruction, necrotizing fasciitis, meningitis, otitis and septic shock, often leading to death. These infections appeared to be caused by beta-hemolytic streptococci (BHS) based on initial culture results (n = 10), though speciation was unclear and some samples (n = 6) produced no growth. Based on PCR results (n = 26), Streptococcus canis was the only bacterial species or the dominant species identified in each sample, and was the only species present in all the regions associated with the pyogenic infections.

CONCLUSIONS AND RELEVANCE

Horizontal gene transfer and loss of the cell wall may account for the discrepancy between the culture and PCR results and the highly pathogenic nature of S canis in this particular population of cats. A large-scale hoarding situation with multiple animal species, overcrowding, stress and mixing of animals from many geographical regions created ideal conditions for these events to occur. The specific virulence factors present may be more useful in predicting the pathophysiology of BHS infections than the species of Streptococcus found in the host per se.

Bivalent ligation of the collagen-binding modules of fibronectin by SFS, a non-anchored bacterial protein of Streptococcus equi

SFS is a non-anchored protein of Streptococcus equi subspecies equi that causes upper respiratory infection in horses. SFS has been shown to bind to fibronectin (FN) and block interaction of FN with type I collagen. We have characterized interactions of a recombinant 60-mer polypeptide, R1R2, with FN. R1R2 contains two copies of collagen-like 19-residue repeats. Experiments utilizing various FN fragments and epitope-mapped anti-FN monoclonal antibodies located the binding site to (8-9)FNI modules of the gelatin-binding domain. Fluorescence polarization and competitive enzyme-linked assays demonstrated that R1R2 binds preferentially to compact dimeric FN rather than monomeric constructs containing (8-9)FNI or a large dimeric FN construct that is constitutively in an extended conformation. In contrast to bacterial peptides that bind (2-5)FNI in addition to (8-9)FNI, R1R2 did not cause conformational extension of FN as assessed by a conformationally sensitive antibody. Equilibrium and stopped-flow binding assays and size exclusion chromatography were compatible with a two-step binding reaction in which each of the repeats of R1R2 interacts with one of the subunits of dimeric FN, resulting in a stable complex with a slow koff. In addition to not binding to type I collagen, the R1R2·FN complex incorporated less efficiently into extracellular matrix than free FN. Thus, R1R2 binds to FN utilizing features of compact soluble FN and in doing so interferes with the organization of the extracellular matrix. A similar bivalent binding strategy may underlie the collagen-FN interaction.

Contribution of fibronectin-binding protein to pathogenesis of Streptococcus equi ssp. zooepidemicus

Streptococcus equi ssp. zooepidemicus (S. zooepidemicus) is responsible for a wide variety of infections in many species. Fibronectin-binding protein is a bacterial cell surface protein, which specifically binds fibronectin (FN). Considering the specific role of FN-binding protein in host-pathogen interactions, we investigated the function of a novel FN-binding domain in the FN-binding protein (FNZ) of S. zooepidemicus. Five recombinant FNZ gene fragments [N1 (amino acids, 38-197), N2 (amino acids, 38-603), N3 (amino acids, 41-315), N4 (amino acids, 192-370), and N5 (amino acids, 38-225)] were expressed in Escherichia coli, and their FN-binding activities were tested. The results showed that amino acids 192-225 in the NH2 -terminal region of FNZ could be responsible for binding fibronectin. The FNZ knockout mutant was constructed in S. zooepidemicus, which results in the reduced capacity to adhere to HEp-2 cell, defective virulence in vivo, decreased biofilm formation, and decreased colonization capacity in blood, liver, lung, and spleen tissues of mice as compared to the wild type. These results suggest that FNZ participates in biofilm formation, FN binding, cell adhesion, and pathogenesis of S. zooepidemicus. Furthermore, this work offers a novel FN-binding domain within FNZ, which will help in further characterization of S. zooepidemicus FN-binding properties.

Streptococcus equi subsp. zooepidemicus meningitis in Peru

A 59-year-old man with a history of fever, unsteadiness, hemiparesis, motor aphasia and consciousness disturbance was hospitalized for Streptococcus equi subsp. zooepidemicus meningitis. He denied contact with farm animals, but had a practice of consuming unpasteurized goats' cheese from an uncertain source.

Purulent meningoventriculitis caused by Streptococcus equi subspecies zooepidemicus in a snow leopard (Panthera uncia)

Streptococcus equi subspecies zooepidemicus (SEZ) is a zoonotic pathogen that causes respiratory tract infections in man and animals. SEZ infections are very rare in felids. This report describes purulent meningoventriculitis caused by SEZ in an approximately 16-year-old male snow leopard (Panthera uncia). The animal exhibited neurological signs and died 1 month after their onset. On necropsy examination, the surface blood vessels of the brain were swollen and there was an increased volume and turbidity of cerebrospinal fluid (CSF). Microscopically, suppurative inflammation accompanied by gram-positive cocci was observed in the meninges and near the ventricles. SEZ was isolated from the brain tissue and CSF. This is the first report of infection with SEZ in a felid other than a domestic cat. This animal had not had direct contact with horses, but it had been fed horse flesh that may have been the source of infection.

Spondylodiskitis secondary to Streptococcus equi subspecies zooepidemicus

Streptococcus equi subspecies zooepidemicus, traditionally classified under Group C Streptococci, is primarily a veterinary pathogen. Rarely, it may cause infections such as bacteremia, meningitis, endocarditis and pneumonia in humans. Musculoskeletal infections secondary to this pathogen are very uncommon. The authors present the first case of osteomyelitis due to S. zooepidemicus in a farmer who had close contact with a dead horse. The authors review all cases of osteoarticular infections secondary to this microbe, in addition to providing an overview of clinical manifestations, treatment and outcome of this infection.

Epidemiology and pathogenicity of zoonotic streptococci

Zoonotic infections caused by Streptococcus spp. have been neglected in spite of the fact that frequency and severity of outbreaks increased dramatically in recent years. This may be due to non-identification since respective species are often not considered in human medical diagnostic procedures. On the other hand, an expanding human population concomitant with an increasing demand for food and the increased number of companion animals favour conditions for host species adaptation of animal streptococci. This review aims to give an overview on streptococcal zoonoses with focus on epidemiology and pathogenicity of four major zoonotic species, Streptococcus canis, Streptococcus equi sub. zooepidemicus, Streptococcus iniae and Streptococcus suis.

Human meningitis from Streptococcus equi subsp. zooepidemicus acquired as zoonoses

Streptococcus equi subsp. zooepidemicus rarely causes meningitis in humans by contact with domestic animals or their unpasteurized products. In this paper we reviewed the literature pertaining to the epidemiological and clinical aspects relating to this infection on previously reported cases of human disease. Additionally, the case of a 51-year-old female who acquired meningitis with this organism after contact with a horse is described. This patient was successfully treated with ceftriaxone, yet penicillin remains the treatment of choice. This aetiological agent should be considered in the proper epidemiological context.

Human bacterial arthritis caused by Streptococcus zooepidemicus: report of a case

Septic arthritis caused by Streptococcus zooepidemicus is a rare event in humans. Of the four cases reported in the literature, only two patients had direct animal contact, and the portal of entry remained unclear in all cases. We report herein the case of a patient who suffered a purulent arthritis of the left shoulder caused by S. zooepidemicus, successfully treated in our department. A diagnostic FDG-PET-CT scan ruled out other foci of infection, but detected a hyperkeratotic plantar chronic soft tissue lesion of the left foot, acquired in a paragliding accident 10 years earlier. The fact that the patient habitually took care of his horses barefoot in boots, identifies the cutaneous portal of entry as most likely. To our knowledge this is the first report of a septic arthritis caused by S. zooepidemicus where a cutaneous entry route is described.

Streptococcus equi subsp. zooepidemicus meningitis

A 72-year-old woman was hospitalized for Streptococcus equi subsp. zooepidemicus meningitis. The same organism was cultured from her two horses. She denied contact with horses, but had a practice of consuming unpasteurized milk from a cow. The cow was in the same stable as the horses, and the ill woman's son milked the cow.

Post streptococcal acute glomerulonephritis secondary to sporadic Streptococcus equi infection

Streptococcus equi subspecies zooepidemicus infection is rare in humans, but a well-known cause of pyogenic disease in cows and horses. S. zooepidemicus uncommonly causes post-strep glomerulonephritis (PSGN) in humans via epidemic outbreaks. We present a sporadic case of post S. zooepidemicus glomerulonephritis in a child most probably contracted from a horse. The 14-year-old girl presented with the typical signs of PSGN, with S. equi zooepidemicus isolated from a blood culture, together with a low C3 and raised anti-DNAse B. This is the first known report of a sporadic case of PSGN in a child caused by this organism.

Outbreak of Streptococcus equi subsp. zooepidemicus infections on the island of Gran Canaria associated with the consumption of inadequately pasteurized cheese

Streptococcus equi subsp. zooepidemicus infections are infrequent in humans. A clinical and epidemiological study of a milk-borne outbreak caused by this organism is described. Fifteen patients (5 females, 10 males) with a median age of 70 years (range 47-86) were infected. Twelve (80%) had underlying diseases. Infection with S. equi subsp. zooepidemicus presented as primary bacteremia in six cases, as bacteremia associated with aortic aneurism in four cases, as septic arthritis in two cases, as pneumonia in two cases, and as meningitis in one case. Five (33.3%) patients died. A case-control study proved that consumption of inadequately pasteurized cheese of a specific brand was associated with S. equi subsp. zooepidemicus disease (OR=4.5; 95% CI 1.57-19.27; p<0.001). This outbreak serves as a reminder that S. equi subsp. zooepidemicus causes serious infections that are usually zoonoses. Identification of beta-hemolytic streptococci to the species level to detect contaminated foods of animal origin is important for preventing new food-borne outbreaks. For a precise characterization of the isolates, the application of molecular markers is recommended.

An outbreak of Streptococcus equi subspecies zooepidemicus associated with consumption of fresh goat cheese

Background

Streptococcus equi subspecies zooepidemicus is a rare infection in humans associated with contact with horses or consumption of unpasteurized milk products. On October 23, 2003, the National Public Health Institute was alerted that within one week three persons had been admitted to Tampere University Central Hospital (TaYS) because of S. equi subsp. zooepidemicus septicaemia. All had consumed fresh goat cheese produced in a small-scale dairy located on a farm. We conducted an investigation to determine the source and the extent of the outbreak.

Methods

Cases were identified from the National Infectious Disease Register. Cases were persons with S. equi subsp. zooepidemicus isolated from a normally sterile site who had illness onset 15.9-31.10.2003. All cases were telephone interviewed by using a standard questionnaire and clinical information was extracted from patient charts. Environmental and food specimens included throat swabs from two persons working in the dairy, milk from goats and raw milk tank, cheeses made of unpasteurized milk, vaginal samples of goats, and borehole well water. The isolates were characterized by ribotyping and pulsed-field gel electrophoresis (PFGE).

Results

Seven persons met the case definition; six had septicaemia and one had purulent arthritis. Five were women; the median age was 70 years (range 54–93). None of the cases were immunocompromized and none died. Six cases were identified in TaYS, and one in another university hospital in southern Finland. All had eaten goat cheese produced on the implicated farm. S. equi subsp. zooepidemicus was isolated from throat swabs, fresh goat cheese, milk tank, and vaginal samples of one goat. All human and environmental strains were indistinguishable by ribotyping and PFGE.

Conclusion

The outbreak was caused by goat cheese produced from unpasteurized milk. Outbreaks caused by S. equi subsp. zooepidemicus may not be detected if streptococcal strains are only typed to the group level. S. equi subsp. zooepidemicus may be a re-emerging disease if unpasteurized milk is increasingly used for food production. Facilities using unpasteurized milk should be carefully monitored to prevent this type of outbreaks.

Identification and characterization of a novel fibronectin-binding protein gene fromStreptococcus equisubspecieszooepidemicusstrain VTU211

This work describes the cloning and sequencing of genes encoding fibronectin-binding proteins from Streptococcus equi subspecies zooepidemicus strain VTU211. A gene encoding a cell-wall protein FNZ was amplified and sequenced. In the same bacterial strain, a second gene termed fnz2 was now discovered, encoding another fibronectin-binding protein (FNZ2). The complete amino acid sequence encoded by fnz2 was deduced and compared to that deduced from fnz. The sequence comparison of the fnz and fnz2 predicted that fibronectin-binding activity is localizing a domain in the C terminal part of FNZ2, since this domain is composed of three repeats, which contain a motif similar to what has earlier been found in other fibronectin-binding proteins in streptococci. Three parts of fnz2 [fnz2(1-8), fnz2(2-4), and fnz2(4-3)] were amplified using polymerase chain reaction and ligated into an expression vector, and recombinant FNZ2 proteins were produced in Escherichia coli. Fibronectin bound to the FNZ2(1-8) [amino acids 212-396] and FNZ2(2-4) (amino acids 36-448) but not to the FNZ2(4-3) (amino acids 36-191) in a Western ligand blot, showing that repeat domain of FNZ2 protein was sufficient for binding of fibronectin. Purified FNZ2(2-4) protein was also shown to display collagen-binding activity to collagen-coated microtiter wells. These results show that recombinant FNZ2 has fibronectin- and collagen-binding activities.

Epidemic glomerulonephritis due to Streptococcus zooepidemicus in Nova Serrana, Brazil

BACKGROUND

In 1998, there was a large outbreak of acute glomerulonephritis in Nova Serrana, Brazil, caused by group C Streptococcus zooepidemicus. This article reviews the characteristics of the outbreak and some aspects of the patients' follow-up.

METHODS

We describe clinical characteristics of patients with acute nephritis. Using case-control studies, we identified the source of infection. Cultures of oropharyngeal swabs from patients were performed. Of 135 patients identified in 1998, available patients were reexamined in a prospective study after 2 and 5 years.

RESULTS

Lancefield group C S. zooepidemicus was identified as the causative organism and linked to the consumption of cheese produced from unpasteurized milk. Of the original group of 134 patients, 4 died in the acute phase and 5 (3.7%) required chronic dialysis. After 2 years, of the 69 cases reevaluated, 94% were adults (mean +/- standard error age: 39 +/- 2 years); we found arterial hypertension in 42% (N= 27/64) of the patients, reduced creatinine clearance (<80 mL/min/1.73 m(2)) in 30% (N= 20/67), and increased microalbuminuria (>20 microg/min) in 34% (N= 22/65). Preliminary data at 5-year follow-up suggest that the percentage of patients with creatinine clearance lower than 60 mL/min increased from 9% to 15%.

CONCLUSION

This article highlights the dangers of consuming unpasteurized dairy products. Follow-up of patients with epidemic poststreptococcal glomerulonephritis due to S. zooepidemicus show that a considerable proportion present hypertension, reduced renal function, and increased microalbuminuria.

Acute bacterial arthritis caused by group C streptococci

OBJECTIVES

To summarize the characteristics of and clinical experience with joint infection by group C streptococcus.

METHODS

Two new cases of acute bacterial arthritis due to group C streptococci are reported, and a MEDLINE search was performed, which located 22 additional cases.

RESULTS

Mean age (+/- standard deviation) of all 24 patients was 46 +/- 25 years, and most patients were men (75%). The species most frequently identified was Streptococcus equisimilis (12 cases). Eight patients (33%) had a general risk factor for infection, and the same percentage had some type of arthropathy. Only 3 patients had previous contact with animals. The infection was polyarticular in a third of cases, and the joint most frequently involved was the knee. The majority of patients showed a good response to the treatment with intravenous penicillin. However, 3 patients had functional sequelae, 2 more had residual radiological lesions, and 3 died.

CONCLUSIONS

Acute bacterial arthritis due to group C streptococci is a serious but uncommon entity that can affect patients without risk factors. Rapid diagnosis and treatment may improve the outcome. Semin Arthritis Rheum 31:43-51.

Comparison of the fibronectin-binding protein FNE from Streptococcus equi subspecies equi with FNZ from S. equi subspecies zooepidemicus reveals a major and conserved difference

The gene fnz from Streptococcus equi subspecies zooepidemicus encodes a cell surface protein that binds fibronectin (Fn). Fifty tested isolates of S. equi subspecies equi all contain DNA sequences with similarity to fnz. This work describes the cloning and sequencing of a gene, designated fne, with similarity to fnz from two S. equi subspecies equi isolates. The DNA sequences were found to be identical in the two strains, and sequence comparison of the fne and fnz genes revealed only minor differences. However, one base deletion was found in the middle of the fne gene and eight base pairs downstream of the altered reading frame there is a stop codon. An Fn-binding protein was purified from the growth medium of a subspecies equi culture. Determination of the NH(2)-terminal amino acid sequence and molecular mass, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, revealed that the purified protein is the gene product of the 5'-terminal half of fne. Fn-binding activity has earlier only been found in the COOH-terminal half of FNZ. By the use of a purified recombinant protein containing the NH(2) half of FNZ, we provide here evidence that this half of the protein also harbors an Fn-binding domain.

Group C streptococcal meningitis: case report and review of the literature

Group C streptococci are a common cause of epidemic bacterial infection in animals. These organisms are a rare but frequently fatal cause of meningitis in humans. We report the case of a 13-year-old girl with meningitis caused by a group C Streptococcus (Streptococcus zooepidemicus) successfully treated with vancomycin and third generation cephalosporins. We also review cases of group C streptococcal meningitis reported previously.

Epidemic nephritis in Nova Serrana, Brazil

BACKGROUND

Outbreaks of nephritis have been rare since the 1970s. From December, 1997, to July, 1998, 253 cases of acute nephritis were identified in Nova Serrana, Brazil. Seven patients required dialysis, and three patients died. We did a case-control study to investigate the cause of the outbreak.

METHODS

Using a matched cluster design, we examined seven recent patients, their family members (n=23), and members of neighbourhood-matched control households (n=22). We subsequently interviewed 50 patients and 50 matched controls about exposure to various dairy products. We also cultured dairy foods and took udder-swab and milk samples from cows.

FINDINGS

Throat cultures indicated that nephritis was associated with group C Streptococcus equi subspecies zooepidemicus, a cause of bovine mastitis. S. zooepidemicus was detected in four of seven case households (six of 30 people) and no control households (p=0.09). Patients were more likely than matched controls to have consumed a locally produced cheese called queijo fresco (matched odds ratio 2.1, p=0.05). The nephritis attack rate was 4.5 per 1000 in Nova Serrana but 18 per 1000 in the village Quilombo do Gaia (p=0.003). The largest supplier of unpasteurized queijo fresco was a farm in Quilombo do Gaia. S. zooepidemicus was not detected in food samples or in swabs collected from cows in August, 1998, although mastitis was evident among cows on the suspected farm. Throat cultures of the two women who prepared cheese on this farm yielded the outbreak strain of S. zooepidemicus. After the cheese was removed from the distribution system, no further cases were reported.

INTERPRETATION

A large outbreak of glomerulonephritis was attributed to S. zooepidemicus in unpasteurised cheese. This outbreak highlights the dangers of consuming unpasteurized dairy products and need for global efforts to promote food safety.

Determination of intraspecies variations of the V2 region of the 16S rRNA gene of Streptococcus equi subsp. zooepidemicus

The 16S rRNA gene of 39 S. equi subsp. zooepidemicus strains and two S. equi subsp. equi strains was amplified by polymerase chain reaction and subsequently digested with the restriction enzyme Hinc II. A restriction profile with two fragments with sizes of 1250 bp and 200 bp could be observed for both S. equi subsp. equi strains and for 30 of the 39 S. equi subsp. zooepidemicus strains indicating a sequence variation within the V2 region of the 16S rRNA gene of the remaining nine S. equi subsp. zooepidemicus isolates. A segment of the 16S rRNA gene including the hypervariable V2 region of 11 S. equi subsp. zooepidemicus and two S. equi subsp. equi could be amplified by PCR and sequenced. The sequence of the V2 region of eight S. equi subsp. zooepidemicus strains appeared to be identical or almost identical to the sequence of the two S. equi subsp. equi strains. The sequence of the remaining three S equi subsp. zooepidemicus strains differed significantly from the sequence of S. equi subsp. equi. These differences allowed a division of S. equi subsp. zooepidemicus strains into two 16S rRNA types and might possibly have consequences for the taxonomic position of these phenotypically indistinguishable strains of one subspecies. A molecular typing could additionally be performed by amplification of the gene encoding the 16S-23S rRNA spacer region. A single amplicon of the spacer gene of 1100 bp could be observed for one S. equi subsp. zooepidemicus, an amplicon of 950 bp for two S. equi subsp. equi strains and 10 S. equi subsp. zooepidemicus strains, a amplicon of 780 bp for 27 S. equi subsp. zooepidemicus strains and a single amplicon of 600 bp for one S. equi subsp. zooepidemicus strain. The variations of the V2 region of the 16S rRNA gene and the size variations of the 16S-23S rRNA spacer gene were not related to each other. Both variations could be used for molecular typing of this species, possibly useful in epidemiological aspects.

The role of hyaluronic acid capsular material of Streptococcus equi subsp. zooepidemicus in mediating adherence to HeLa cells and in resisting phagocytosis

Hyaluronic acid is thought to be one of the critical virulence factors of Streptococcus equi subsp. zooepidemicus. The present study was designed to study the role of hyaluronic acid capsular material in mediating adherence and to resist the phagocytosis of the host's immune defence. The studies were performed with two encapsulated S. equi subsp. zooepidemicus and two unencapsulated phase variants. The bacteria had been previously isolated from diseased pigs and monkeys in Indonesia. The presence of capsular material was determined using the hyaluronic acid decapsulation test and by electron microscopic studies. Both encapsulated bacteria showed mucoid colonies after cultivation on blood agar, grew with diffuse colonies in soft agar media and reacted negatively in the salt aggregation test. The unencapsulated bacteria grew with small colonies on blood agar, formed compact colonies in soft agar media and reacted positively in the salt aggregation test. Adherence and phagocytosis studies revealed that the encapsulated bacteria adhered significantly more to HeLa cells and were less phagocytosed by murine macrophages compared to unencapsulated bacteria. Pretreatment of the HeLa cells using hyaluronic acid or pretreatment of the bacteria by hyaluronidase decreased the adherence value of encapsulated bacteria. Pretreatment of bacteria with pronase had no effect. The presented results strongly indicate that the hyaluronic acid capsular material contributes to adherence properties of S. equi subsp. zooepidemicus and might help the bacteria to resist phagocytosis by macrophages.

SFS, a novel fibronectin-binding protein from Streptococcus equi, inhibits the binding between fibronectin and collagen

The obligate parasitic bacterium Streptococcus equi subsp. equi is the causative agent of strangles, a serious disease of the upper respiratory tract in horses. In this study we have, using shotgun phage display, cloned from S. equi subsp. equi and characterized a gene, called sfs, encoding a protein termed SFS, representing a new type of fibronectin (Fn)-binding protein. The sfs gene was found to be present in all 50 isolates of S. equi subsp. equi tested and in 41 of 48 S. equi subsp. zooepidemicus isolates tested. The sfs gene is down-regulated during growth in vitro compared to fnz, a previously characterized gene encoding an Fn-binding protein from S. equi subsp. zooepidemicus. Sequence comparisons revealed no similarities to previously characterized Fn-binding proteins, but high scores were obtained against collagen. Besides similarity due to the high content of glycine, serine, and proline residues present in both proteins, there was a nine-residue motif present both in collagen and in the Fn-binding domain of SFS. By searching the Oklahoma S. pyogenes database, we found that this motif is also present in a potential cell surface protein from S. pyogenes. Protein SFS was found to inhibit the binding between Fn and collagen in a concentration-dependent way.

Septicemia and meningitis due to Streptococcus zooepidemicus

A case of septicemia and meningitis due to Streptococcus zooepidemicus in an immunocompetent patient is reported. This organism is an uncommon human pathogen that sometimes causes severe infection, usually in immunocompromised patients. In the reported case, the patient required to be mechanically ventilated for one week and was treated with intravenous ampicillin and gentamicin. He recovered and was discharged from hospital three weeks after the initial presentation. Streptococcus zooepidemicus sensitive to all penicillins, was isolated from all blood cultures and the cerebrospinal fluid.

Bacterial arthritis due to beta-hemolytic streptococci of serogroups A, B, C, F, and G. Analysis of 23 cases and a review of the literature

The clinical features, essential laboratory findings, management, and outcome of all 23 cases of septic arthritis caused by different serogroups of beta-hemolytic streptococcus (BHS) seen at the Stanford Medical Center, Stanford, CA, from July 1, 1985, through October 31, 1996, were reviewed and compared to those found in the literature. Group A streptococci (GAS) accounted for 9 (40%) of our cases; group B (GBS), for 7 (30%); and Group G (GGS), for 7 (30%). No cases were caused by Group C (GCS) or F (GFS) during this period. During the same period, GAS accounted for 66 (33%) of 200 cases of bacteremia due to BHS, GBS, for 98 (49%); GCS, for 12 (6%); GFS, for 4 (2%); and GGS, for 20 (10%). A review of potential risk factors revealed that, with the exception of GGS, male and female patients were almost equally distributed among each of the serogroups. Patients aged 50 years and older comprised 56%-77% of each group. Associated conditions and risk factors were present among most patients (19/23, 83%); autoimmune diseases and a chronic skin wound or trauma were notably present among patients with GAS, while diabetes mellitus and malignancy were more common among patients with GBS. Infected prosthetic implants were present in 7 patients, including 4/7 patients with GGS. All patients had positive cultures of synovial fluid, and 11/23 (49%) had positive blood cultures (GAS, 5/9; GBS, 6/7; and GGS, 0/7). The clinical presentation and hospital course of patients infected with the different serogroups varied. Patients infected with GAS had the most severe disease and those with GGS the least severe. Necrotizing fascitis, shock, DIC, and admission to the intensive care unit were found only among patients infected with GAS. Despite aggressive management with antimicrobial therapy and surgery, 4/23 patients died (3 patients with GAS; 1 with GBS). The isolates from our patients were not available for study; investigations by others of the biology of BHS suggest that the production of 1 or more of the streptococcal pyrogenic exotoxins by isolates of GAS may account for the differences in the severity of disease among our patients with septic arthritis caused by different serogroups of BHS. Although septic arthritis due to BHS is uncommon, such patients provide a valuable model to study features of the host-parasite interaction that may contribute to the observed differences in severity of disease.

An outbreak of Streptococcus equi ssp. zooepidemicus infection of probable human origin in Wanderoos (Macaca silenus)--case report

Three out of ten young to adult wanderoos (M. silenus) of a breeding colony at the Rheine Zoo died within two days from a peracute illness, characterized by salivation, vomiting, apathy and minor CNS symptoms. Streptococcus equi ssp. zooepidemicus was isolated in pure cultures from all organs of two animals investigated bacteriologically. The strains were penicillin-susceptible, and penicillin treatment of all remaining animals cured two already sick animals and prevented further cases. A volunteer worker with upper respiratory disease was suspected as source of infection; contact with equine materials and rodents could be excluded.

Pyogenic arthritis caused by streptococcus equisimilis (group-C streptococcus) in a patient with AIDS

A patient with the Acquired ImmunoDeficiency Syndrome (AIDS) treated with a daily low dose of corticosteroids for chronic atopic dermatitis experienced a sudden episode of unilateral knee arthritis. Culture of the purulent synovial liquid yielded a pure culture of Streptococcus Equisimilis. A four week period of intravenous antibiotherapy combined with repeated drainages allowed a complete recovery of articular function.

Identification and molecular characterization of serological group C streptococci isolated from diseased pigs and monkeys in Indonesia

The present study was designed to comparatively investigate 34 beta-hemolytic streptococci isolated from infected pigs and monkeys from various islands in Indonesia. According to the serological and biochemical data, all 34 isolates were Lancefield's serological group C streptococci and could be identified as Streptococcus equi subsp. zooepidemicus. Of the 34 group C streptococci investigated, 28 grew on solid media in large, mucoid colonies, in fluid media at a uniform turbidity, and in soft agar in diffuse colonies. A decapsulation test with a hyaluronidase-producing Staphylococcus aureus strain revealed the hyaluronic acid nature of the capsular material. The remaining six streptococci grew on solid media in small, nonmucoid colonies, in fluid media as sediment with clear supernatant, and in soft agar in compact colonies. Determination of surface hydrophobicity by salt aggregation revealed a hydrophilic surface for the encapsulated bacteria and a hydrophobic surface for the unencapsulated group C streptococci. To further analyze the epidemiological relationships, all 34 mucoid and nonmucoid isolates from pigs and monkeys were subjected to protein and DNA fingerprinting. The latter was performed by pulsed-field gel electrophoresis. The protein profiles of all 34 isolates and the DNA profiles of 32 isolates appeared to be identical, with the DNA profiles of 2 isolates being closely related, indicating that a single virulent clone is responsible for this disease outbreak in Indonesia.

Genetic structure of populations of beta-haemolytic Lancefield group C streptococci from horses and their association with disease

The genetic structure of beta-haemolytic Lancefield group C streptococci isolated from horses in Australia was examined by multilocus enzyme electrophoresis. The 249 isolates comprised 70 classified phenotypically as Streptococcus equi subspecies equi, 177 classified as S equi subspecies zooepidemicus and two which were unclassifiable. Forty-one electrophoretic types were identified which could be classified into three major clusters, A, B and C. Of the isolates, 178 fell into cluster B (types 4 to 22) and lay within a genetic distance of 0.36. Sixty-nine of the 70 S equi subspecies equi isolates fell into type 12, which suggests that they were members of a single clone, and the isolates from abscesses were significantly more likely to belong to type 12 than those from horses with no clinical signs (P < 0.001). There were no other significant associations between electrophoretic types or clusters and the isolation of the organism from particular sites. These data suggested that S zooepidemicus may be the archetypal species from which the clone designated subspecies equi has been derived. If isolates of the subspecies equi from other geographical regions also prove to be members of electrophoretic type 12, this hypothesis would be strengthened.

Investigation of milk-borne Streptococcus zooepidemicus infection associated with glomerulonephritis in Australia

An outbreak of infection due to Streptococcus zooepidermicus is reported. The index case was a patient who suffered an episode of septicaemia complicated by glomerulonephritis. Two other persons in his family were found to be asymptomatic throat carriers. The source of the outbreak was unpasteurised milk from a house cow on the farm where the family lived. Molecular studies confirmed that the strains isolated from the index case, the other family members and the cow's milk were identical. Although a renal biopsy was not performed, the diagnostic criteria for poststreptococcal glomerulonephritis were satisfied. The organism is an uncommon human pathogen that sometimes causes outbreaks of severe infection which may be associated with glomerulonephritis.

Fatal infection associated with group C streptococci

Serious infection caused by Lancefield group C streptococci is unusual in man. Two unrelated deaths associated with these organisms in a 55 year old woman who died after three days of diarrhoea and vomiting, and in a 65 old man who died after a week of non-specific symptoms, are presented. Post mortem examination showed septicaemia in the former and severe aortic stenosis with widespread septic emboli and probable meningitis in the latter. Lancefield group C streptococci were isolated from both cases. These organisms may be carried asymptomatically and usually cause disease in animals but cases of serious human infection have recently been described, mainly in elderly patients or those with other predisposing factors.

Equine glomerulonephritis and renal failure associated with complexes of group-C streptococcal antigen and IgG antibody

A 12-year-old thoroughbred gelding died from diffuse global glomerulonephritis, 3 months after a lower respiratory infection from which Streptococcus zooepidemicus was isolated. Immunopathological studies (immunofluorescence, immunodiffusion, immunoperoxidase testing and immunoblotting) indicated the presence of an immune reactant renal disease associated with IgG antibody and streptococcal antigens.

Pharyngeal and tonsil infections caused by non-group A Streptococcus

Non-group A streptococci are members of the genus Streptococcus but do not share the notoriety of their cousin from group A. Most physicians, including otolaryngologists and head and neck surgeons, do not associate them with upper respiratory tract and head and neck infections. Some laboratories do not bother to report their presence on culture. At the University of California, Los Angeles they have been shown to cause (1) tonsillitis, painful tonsils lacking exudate and erythema (group C, one case; group F, one case), (2) acute nonexudative tonsillitis (group B, two cases; group C, one case; group F, one case), and (3) acute exudative tonsillitis (group C, one case). It should be remembered when there is a report of their presence that they are usually vulnerable to penicillin and its analogs. By judicious use of these drugs, morbidity can be diminished.

Streptococcus zooepidemicus (Lancefield group C) septicaemia in Hong Kong

The clinical findings relating to 11 patients in Hong Kong (HK) and to 43 patients described elsewhere, all with Streptococcus zooepidemicus septicaemia, are reviewed. There was a particular association with cardiovascular disease (27%) with seven cases of endocarditis, three of abdominal aortic aneurysm and two of deep venous thrombosis. Associations not previously reported included two cases of pharyngitis and two patients with persistent post-operative fever. The overall mortality was 22%. Both human and porcine strains of S. zooepidemicus from HK did not hydrolyse aesculin in contrast to the aesculin-positive biotypes reported previously. HK strains also had very mucoid colonies and capsules of hyaluronic acid were seen in electron micrographs. Samples of chromosomal DNA, extracted by means of HindIII restriction endonuclease, of strains from human beings and pigs were identical. The MIC of penicillin for all strains was less than or equal to 0.03 mg/l but the MBC for all was greater than 32 mg/l. Penicillin alone is generally sufficient for cure but combination with an aminoglycoside may be indicated in seriously ill patients. In our locality, pigs were incriminated as a possible source of human infection whereas consumption of contaminated dairy products is important elsewhere.

Group C streptococcal pleurisy and pneumonia: a fulminant case and review of the literature

A 30-year-old, previously healthy patient developed a pleurisy and pneumonia due to group C streptococcus, with multiple medical complications, including bilateral empyemas. Eight other reported cases of group C streptococcal pneumonia are reviewed.

Streptococcus zooepidemicus cellulitis and bacteraemia in a renal transplant recipient

A case of renal transplant recipient with Streptococcus zooepidemicus (Lancefield group C) cellulitis and bacteraemia is described. Human infections with this organism are very rare and this is the first case report of cellulitis caused by S. zooepidemicus. While animals are the reservoir for most human infections, a source was not defined in this patient.

Group C streptococci in human infection: a study of 308 isolates with clinical correlations

A collection of 308 clinical isolates of beta-haemolytic Lancefield group C streptococci was assembled from laboratories in England, Nigeria and New Zealand. Of these, 276 isolates were Streptococcus equisimilis, 23 S. milleri and nine S. zooepidemicus. Isolates of S. equisimilis in the African collection, though few, gave higher rates of lactose and raffinose fermentation, aesculin hydrolysis and positive alpha-galactosidase reactions than those from elsewhere. Erythromycin resistance was found in 1.9% of the English isolates of S. equisimilis. Strains from superficial infections accounted for 88% of the collection and were most commonly isolated from the upper respiratory tract, skin or wounds. Amongst the 36 patients yielding isolates from deep sites S. equisimilis was found in septicaemia, cellulitis, abscess, peritonitis, septic arthritis, pneumonia, mycotic aneurysm and acute epiglottitis, S. milleri was found in abdominal abscesses, peritonitis, pleural empyema and osteomyelitis and S. zooepidemicus was found in septicaemia, pneumonia, meningitis and septic arthritis. Within the collection an unselected general catchment of 214 isolates of group C streptococci from the laboratories in Yorkshire showed the following species: from 199 superficial infections 94% S. equisimilis, 5% S. milleri and 1% S. zooepidemicus and 15 patients with deeper, more aggressive infections 67, 27 and 6.7% of these species respectively.

Invasive streptococcal infections in the era before the acquired immune deficiency syndrome: a 10 years' compilation of patients with streptococcal bacteraemia in North Yorkshire

Significant streptococcal (non-pneumococcal, non-enterococcal) bacteraemia was detected in 100 patients in two Health Districts of North Yorkshire in the decade 1978-1988. Patients with these infections accounted for 11% of the total 902 patients in the districts in whom bacteraemia was diagnosed during the period. Infection was most often seen with beta-haemolytic streptococci (52 patients) comprising Lancefield group A (Streptococcus pyogenes) (20 patients), group B (13), group C (5), group G (9), haemolytic Streptococcus milleri and non-groupable streptococci (5). The wide variety of serious infections included cellulitis, abscess, septicaemia, pneumonia, septic arthritis, necrotising fasciitis, acute endocarditis and mycotic aneurysm. Of these 52 patients, 21 (40%) died. alpha-Haemolytic streptococcal bacteraemia was diagnosed in 38 patients of whom 24 (63%) suffered from endocarditis and three (8%) died. Three of ten patients with non-haemolytic or anaerobic streptococcal bacteraemia died also. Six of the 100 patients with streptococcal bacteraemia had concomitant acute virus infections. Of the total 56 patients with infective endocarditis diagnosed in the districts during the period, streptococci were responsible in 30 (54%) of them. The predisposing factors, clinical features and outcome of the infections are described and discussed.

A milk-borne outbreak of serious infection due to Streptococcus zooepidemicus (Lancefield Group C)

An outbreak of infection due to Streptococcus zooepidemicus (Lancefield Group C) is described. At least 11 patients were affected and the infection was responsible for, or contributed to, the deaths of seven of these. Clinical features included septicaemia, meningitis and endocarditis. The source of infection was unpasteurized milk from a dairy herd with mild intermittent mastitis.