Urinary tract infection by Streptococcus equinus: a pediatric case presentation

Full Text

Introduction

Streptococcus equinus is a non-enterococcal group D Streptococcus, which colonizes both humans and animals and is involved in food fermentation. It is a Gram positive, non-hemolytic, lactic acid, bile-esculin positive, non-lactose and non-mannitol fermenting bacterium. It is found predominantly in the alimentary tract of horses, and it is associated with specific diseases, such as osteoarticular infections, meningitis, biliary infections, infective endocarditis and colorectal cancer) (Marmolin et al., 2016; Kaiki et al., 2021; Vinciguerra et al., 2021). The incidence of colonization in humans increases in rural areas, where there is high risk of exposure to animal feces and fermented food products (Kaiki et al., 2021; Vinciguerra et al., 2021). Urinary tract infections are among the most frequent infections worldwide. They are detected in hospital and primary care consultations, and in some cases they are asymptomatic. Timely diagnosis and treatment of urinary tract infections can prevent from serious consequences. Urinary tract infections from Streptococcus equinus are very rare. The aim of our study is to present an asymptomatic pediatric case of urinary tract infection by Streptococcus equinus, acquired due to leisure time spent with horses.

Case presentation

A 10-year-old male patient, asymptomatic, without underlying medical conditions, was referred for routine check-up to the Outpatient Pediatric Clinic of the Nikea General Hospital, Piraeus, Greece. According to patient history, he had spent two weeks at a summer camp, where he had direct contact with horses, such as horse riding, horse feeding, watering, horse care etc. His οlder brother, although he had the same contacts and activities, did not present any infection. Examinations of the eyes, mouth, ears, nose, throat and abdomen were normal. Laboratory tests, such as complete blood count, biochemical tests, urinalysis and urine culture were performed.

Materials and methods

The complete blood count was measured on the NIHON KOHDEN CelltacG hematology analyzer, biochemical tests were measured on the KONELAB 60 biochemistry analyzer, urinalysis was performed by the Multistix 10 SG Reagent Strips (Siemens Healthineers), and the urine cultures were performed on Columbia blood agar. For microbial identification, RapID STR REMEL™ (Thermo Scientific System), Gram stain and agglutination with streptococcal group sera (Streptococcal Grouping Kit, Oxoid Ltd., Basingstoke, UK) were applied. In addition, the drug susceptibility testing of the urine culture was performed by the Kirby Bauer disk diffusion susceptibility test, by implementing the EUCAST (European Committee on Antimicrobial Susceptibility Testing) 2023 criteria.

Results

Haematology tests showed mild leukocytosis (12 000/mm³ with 80% neutrophils) and slightly increased erythrocyte sedimentation rate (30 mm/h). Biochemical test results were as follows: glucose 86 mg/dL, urea 30.5 mg/dL, uric acid 6.63 mg/dL, creatinine 0.98 mg/dL, GGT 22 U/L, GOT 20 U/L and GPT 22 U/L. Urinalysis and microscopy revealed bacteriuria by nitrite test and pyuria. The urine culture grew monomicrobial Streptococcus equinus > 10⁵ CFU/ml. Antimicrobial susceptibility testing revealed resistance to Clindamycin, Tetracycline, Cefotaxime and high susceptibility to Erythromycin. The patient received treatment with Erythromycin and recovered quickly.

Discussion

Equines play an important role in transmitting several zoonotic diseases to humans. The emergence and re-emergence of equine zoonotic pathogens have been described by many authors in the literature. Streptococcus equinus has been isolated from the bowel in approximately 7% of the general population. It has rarely been described as a human pathogen. Infections in humans are most often associated with bacteremia, with or without endocarditis (Chayakulkeeree et al., 2015; Marmolin et al., 2016; Jans and Boleij, 2018; Pompilio et al., 2019). Moreover, Streptococcus equinus has been detected in food products including fermented milk in sub-Saharan Africa, Asia and Southern Europe, fermented fish in Asia and fermented plants in sub-Saharan Africa and Latin America suggesting a wide range of habitats and its adaptability to different environmental conditions (Khurana et al., 2015; Jans and Boleij, 2018; González-de la Cruz et al., 2021; Öberg et al., 2022). Streptococcus bovis/Streptococcus equinus complex (SBSEC), consists of commensal bacteria, mainly described as colonizers of the rumen, crop, and cloaca of animals and colon of humans, with a fecal carriage rate of SBSEC in humans ranging from 5% to over 60% (Khurana et al., 2015; Öberg et al., 2022). The variation of the percentage observed, is attributed to different detection techniques and regional differences. Moreover, most studies include specific population groups and not the general population (Jans et al., 2012; Lopes et al., 2014; Dekker and Lau, 2016). Epidemiological data about Streptococcus equinus are limited. The rare published cases include infective endocarditis cases (Keerty et al., 2021; Vinciguerra et al., 2021; Öberg et al., 2022; Stummer et al., 2023), bacteremia (Chayakulkeeree et al., 2015; Marmolin et al., 2016; Kaiki et al., 2021; Öberg et al., 2022; Stummer et al., 2023) and one case of endocarditis combined with histocytosis (Sechi et al., 2000). In 2013 three cases of Streptococcus equinus subspecies zooepidemicus were detected in Eastern Finland, in patients who were horse trainers and breeders. It is noteworthy that the disease in all three patients was invasive and severe, requiring prolonged treatment and rehabilitation. Human infections with Streptococcus equinus subspecies zooepidemicus, are very rare and are generally associated with contact with horses, and consumption of unpasteurized milk products, goat cheese or pork. In most cases S. zooepidemicus leads to fulminant infections (Pelkonen et al., 2013; Stummer et al., 2023). Urinary tract infections are much less common and their role of the SBSEC (Streptococcus bovis/Streptococcus equinus complex) as urinary pathogens is not well known (Matesanz et al., 2015; de Teresa-Alguacil et al., 2016; Rosales-Castillo et al., 2022). In Greece, there are no epidemiological surveillance data from the National Public Health Organization for Streptococcus equinus infection, probably due to its rarity. In the recent past, no similar infections have been detected nor published in Greece, concerning any population age group. The patient in this case, during the stay at the summer camp, had probably contact with horse feces during the relevant activities and therefore was infected. No epidemiological data from the campsite were collected. The child was asymptomatic and the urine culture was performed on the basis of routine testing, so there may be cases of infection which have been under-diagnosed. The 10 year old patient has a higher risk of being infected, due to poor application of hygiene rules in his age group during vacations, without the supervision of parents or teachers. In Greece, horse riding is not a widespread sport and leisure with horses is very limited. Contact with horses occurs in most cases due to agricultural activities. Moreover, a National Equine Registry has not yet been established, despite the continuous efforts of the relevant animal welfare associations (Hellenic Society for the Equine Welfare and Panhellenic Equine Welfare Society). There is an increasing evidence that antibiotic resistance is widespread among Streptococcus equinus clinical isolates, with variable resistance rates reported for clindamycin, erythromycin, tetracycline, and levofloxacin (Boyle et al., 2018; Pompilio et al., 2019; Bohlman et al., 2023; Chhabra et al., 2023). Given the increasing infection rates it is of utmost importance to continuously evaluate the resistance profiles, as well as to determine the factors that enable colonization and establishment in animal and humans, in order to develop strategies to reduce public health risks. The diseases of equines put at risk significant part of the population, such as veterinarians, animal handlers, horse trainers and breeders, animal health personnel, the population of agricultural communities, as well as the general population that gets in contact with horses during sports or leisure time (Bohlman et al., 2023; Chhabra et al., 2023).

 

Figure. Identification of S. equinus by RapID™ REMEL ONE

 

Conclusion

Streptococcus equinus is a rare Gram-positive bacterium, that may cause fulminant infection in humans. In this paper we describe a rare asymptomatic pediatric case of urinary tract infection with S. equinus, as a result of contact with horses. All clinicians and laboratory physicians should be alert for timely diagnosis and specific therapeutic treatment, aiming to ensure the quality of life of patients and increase their survival expectancy.

About the authors

C. Seitopoulou

Nikea Prime Care Center

Email: antoniamour@yahoo.com

MD, MSc in Occupational and Enviromental Health, PhDc, Biopathologist, Laboratory of Biopathology

Греция, Nikea

M. Stamouli

Naval and Veterans Hospital of Athens

Email: antoniamour@yahoo.com

BSc, MSc in Health management, MSc in TQM, EurSpLM, Director of Biochemistry Laboratory

Греция, Athens

G. Kalliora

National and Kapodistrian University of Athens

Email: antoniamour@yahoo.com

Student at Faculty of Biology

Греция, Athens

Antonia Mourtzikou

GHNP “Agios Panteleimon”

Author for correspondence.
Email: antoniamour@yahoo.com

BSc, MSc in Clinical Chemistry, MPH, MPHM, EurSpLM, PhD, Scientific Senior Supervisor, Laboratory of Molecular Diagnostics

Греция, Piraeus

References

Supplementary files