Strep carrier
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Understanding the Strep Carrier State: Key Insights and Implications
Differentiating Acute Infection from Carrier State
Group A Streptococcal Infections and Carrier State
The distinction between an acute infection and a carrier state of Group A Streptococcus (GAS) is crucial due to the potential severe complications associated with acute infections, such as acute rheumatic fever and acute glomerulonephritis. These complications are typically linked to new acquisitions and acute infections rather than the carrier state1. Despite this, a significant portion of the population, particularly school-aged children, may test positive for GAS without showing symptoms, complicating diagnosis and treatment decisions1.
Serologic Studies for Differentiation
Serologic studies targeting nonspecific streptococcal extracellular products, such as streptolysin O and DNase B, have been suggested as useful tools in differentiating between the carrier state and acute infection. Longitudinal analyses have shown that certain families can harbor specific streptococcal types for extended periods without developing severe sequelae, indicating a carrier state rather than an acute infection1.
Detection Methods for Silent Carriers
Carrier Detection in Strangles Outbreaks
In the context of Streptococcus equi ssp. equi (S. equi) following strangles outbreaks, silent carriers can persist for months to years. Studies have shown that qPCR is more sensitive than culture methods in detecting carriers. For instance, in two outbreaks, qPCR identified a higher percentage of carriers compared to culture methods, suggesting that even qPCR-positive but culture-negative horses should be suspected carriers of live bacteria2. This highlights the importance of using sensitive detection methods to identify and manage carriers effectively.
Implications for Public Health and Treatment
Transmission and Public Health Concerns
Not all carriers of hemolytic streptococci are equally capable of transmitting the infection. Historical studies have indicated that the number of streptococci expelled by carriers plays a significant role in their potential to spread the infection. This suggests that some carriers may pose a higher risk of transmission than others, necessitating targeted public health interventions4.
Vaccine Development
Efforts to develop a vaccine against Group A Streptococcus are ongoing. A recent Phase I trial of a 30-valent M protein-based vaccine showed promising results, with the vaccine being well-tolerated and immunogenic in healthy adults. This vaccine elicited significant antibody responses and demonstrated opsonophagocytic killing activity against various M types of Strep A, supporting further clinical development3.
Conclusion
Understanding the distinction between acute infections and carrier states of streptococcal bacteria is essential for effective diagnosis, treatment, and public health management. Sensitive detection methods, such as qPCR, are crucial for identifying silent carriers, while ongoing vaccine development offers hope for reducing the burden of these infections. Public health strategies must consider the varying transmission potentials of different carriers to mitigate the spread of streptococcal diseases effectively.
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Most relevant research papers on this topic
Group A streptococcal carrier versus acute infection: the continuing dilemma.
Defining acute group A streptococcal infection from carrier state is crucial for preventing invasive disease and transmission, as carriers often develop elevated nonspetcoccal antibody responses without developing nonsuppurative sequelae.
Long term silent carriers of Streptococcus equi ssp. equi following strangles; carrier detection related to sampling site of collection and culture versus qPCR.
qPCR is the most effective method for detecting long-term silent carriers of Streptococcus equi in horses, as guttural pouch sampling and appearance do not capture all carriers.
Observational StudySafety and immunogenicity of a 30-valent M protein-based group a streptococcal vaccine in healthy adult volunteers: A randomized, controlled phase I study.
The 30-valent M protein-based streptococcal vaccine was well-tolerated and immunogenic in healthy adults, supporting further clinical development.
RCT
Rigorous JournalThe Problem of the " Dangerous Carrier " of Hemolytic Streptococci. I. Number of Hemolytic Streptococci expelled by Carriers with Positive and Negative Nose Cultures.
The most important difference between carriers of hemolytic streptococci is the number of streptococci they are capable of expelling, rather than a fundamental biological change in their tissues.
GROUP A HEMOLYTIC STREPTOCOCCUS ANTIBODIES. II. GRIFFITH TYPE AGGLUTININ AND ANTISTREPTOLYSIN TITERS IN CARRIERS AND NON-CARRIERS.
High titers of circulating antibodies against Group A hemolytic streptococci were found in individuals harboring the bacteria in their tonsils, suggesting a potential immune response to infection.
The Group A Streptococcal Carrier State Reviewed: Still an Enigma.
The group A streptococcal carrier state remains an enigma, with current research focusing on definition, epidemiology, and pathogenesis, while trials of antimicrobial agents show promising results in eradication.
Highly CitedPreclinical safety and immunogenicity of Streptococcus pyogenes (Strep A) peptide vaccines
The two candidate Strep A peptide vaccines show no clinical toxicity and robust immunological response in rats, suggesting their safety for phase 1 clinical trials in healthy humans.
Rigorous JournalStudies of the carrier state following infection with group A streptococci. 1. Effect of climate.
Climate plays a significant role in the persistence of group A streptococci in the upper respiratory tract after pharyngitis, with varying durations and varying levels of infection.
Observational StudyIdentification and immunoprotective analysis of a Streptococcus iniae subunit vaccine candidate.
Sip11, when delivered by a live bacterial carrier, is an effective vaccine candidate against Streptococcus iniae infection in Japanese flounder.
Highly CitedEvaluation of Detect-A-Strep and the Culturette Ten-Minute Strep ID kits for detection of group A streptococcal antigen in oropharyngeal swabs from children
Both Detect-A-Strep and Culturette 10-Minute Group A Strep ID kits are not sufficiently sensitive to replace our culture method for detecting group A streptococci in oropharyngeal swabs from children.
In Vitro Study