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Do you know why Streptococcus dysgalactiae is called the “bad milk bacteria”?
In the field of microbiology, some bacteria are named after their characteristics. Streptococcus dysgalactiae, commonly known as the "bad milk bacteria," is not named by accident. This bacterium causes mastitis in the mammary glands of animals, especially cattle, which affects the quality of dairy products. This article will take a closer look at the characteristics of this bacterium, its disease manifestations in animals and humans, and analyze its importance in modern society.
Streptococcus dysgalactiae is a Gram-positive, beta-hemolytic coccus belonging to the family Streptococcus.
Characteristics and classification of bacteria
Streptococcus dysgalactiae is a common bacterium that infects humans and animals and is usually found in the intestinal tract and reproductive tract. In humans, the bacteria can cause diseases ranging from superficial skin infections to more serious necrotizing fasciitis and bloodstream infections. In animals, S. dysgalactiae causes mastitis, especially in cows, and arthritis, among other problems, in sheep.
EpidemiologyCurrently, S. dysgalactiae can be divided into two subspecies: Streptococcus dysgalactiae subsp. equisimilis, which is primarily associated with human disease, and Streptococcus dysgalactiae subsp. dysgalactiae, which is mostly seen in the veterinary field.
S. dysgalactiae was previously considered non-pathogenic to humans, but the number of cases of infection has increased in recent years. In some areas, the incidence of invasive infections exceeds that of Streptococcus pyogenes. Studies have shown that the infection is particularly dangerous to the elderly, and the proportion of healthy carriers is inversely correlated with age. Additionally, people with any chronic illness, such as cancer or diabetes, are also particularly susceptible to infection.
Role in human diseaseS. dysgalactiae subspecies equisimilis is a commensal bacterium in the human intestinal and reproductive tract. Noninvasive disease presents most often as tonsillitis and skin infections, and in some cases it has also been implicated as an underlying cause of cellulitis. Notably, the role of this bacterium in skin and soft tissue infections may be underestimated, and its association with cellulitis cases was confirmed in a recent study.
Currently, about 20% of clinical cases are primary bloodstream infections, and it is not easy to find a clear lesion in these infections.
Role in Animal Diseases
In veterinary medicine, S. dysgalactiae affects a variety of animal hosts, especially in dairy cattle, where the bacterium is considered the main etiological agent of mastitis. In some areas, it is the second leading cause of clinical and subclinical mastitis after Staphylococcus aureus.
Treatment and Antimicrobial Sensitivity
Penicillin remains the drug of choice for the treatment of streptococcal infections, and penicillin-resistant strains of S. dysgalactiae have not been reported. As drug resistance becomes a growing problem, the use of second-line drugs such as macrolides and clindamycin has become more common, but some regions have shown an increase in resistance.
Future Research Directions
While current research on S. dysgalactiae has revealed its role in infection, detailed studies on its pathogenic mechanisms remain limited. The diverse pathogenic factors and their relationship with human and animal diseases also need to be further explored. With the increasing incidence of antibiotic resistance and emerging pathogens, a deeper understanding of this bacterium will be a focus of future research.
With the increasing role of S. dysgalactiae in human and animal health, should we re-evaluate and strengthen our understanding of this "bad milk bacteria" and implement more comprehensive prevention and treatment measures against its potential harm? Woolen cloth?
