When we think of Scarlet fever, we think of the Victorian era, of the Velveteen Rabbit and Little Women. Since the invention of antibiotics broke the back of bacterial disease in the 1940s, Scarlet fever has been confined to the history books. Or so we thought.
Outbreaks of S. pyogenes have been steadily increasing since the 1980's, in part due to the rise of more infectious serotypes.
This year, scarlet fever hit Hong Kong causing at least 600 new cases of this disease, and two fatalities, who were both children. The cause of this outbreak could be traced to two new strains of S. pyogenes, both of which acquired mutations that made them more virulent than others previously seen. The reasons that two separate strains decided to suddenly become superbugs at the same time is a subject for speculation. It is known that these strains had developed an increased resistance to erythromycin, probably obtained from commensal bacteria found in the oropharynx or the urogenital tract.
But this wasn't necessarily a cause for alarm. Whilst the increased resistance to erythromycin in these strains was worrying, it wasn't new. Erythromycin resistance has been seen in other strains, and is generally not prescribed to treat S. pyogenes. Unlike other pathogens, S.pyogenes has stubbornly remained vulnerable to penicillin.
“The fact that we still have penicillin is something we all get down on our knees and say prayers about each night.” is what Edward Kaplan, the elder statesman of streptococcal research had this to say of the Hong Kong outbreak. That only two children died from this outbreak is a testament to how far we've come medically since the early 20th century, and a testament to the success of penicillin.
However, a report from Japan suggests that this situation could be changing.
The researchers set out to explain recurrent episodes of streptococcal pharyngitis. When a patients get pharyngitis, after seemingly clearing infection, it is difficult for researchers to determine whether they were re-infected with S. pyogenes, or whether the S. pyogenes had somehow survived the treatment. With this study, the researchers wanted to answer this question once and for all.
So between the years of 2006-2008 they set up shop at the Asahikawa Kosei hospital. Whenever a patient presented with pharyngitis, the doctors at the hospital sent on a sample of the bacteria recovered fromt he patient on to the researchers for further analysis. The researchers would then serotype the strains, and work out what virulence factors they tend to produce, and what antibiotics they are resistant to. using this information allowed the researchers to identify individual strains of bacteria, and track how they spread through the community.
When a patient got an initial infection with S. pyogenes , the researchers got a sample of the bugs. If the infection recurs and the patient returns to hospital, the researchers got another sample from the same patient. So they could take the first sample, and compare it to the second sample to decide whether what had happened was a re-infection with a new strain of bacteria, or whether it was the same strain that they had before.
However, a nasty surprise awaited the researchers when they tested the bacteria for antibiotic resistance. They found two instances of S. pyogenes which showed resistance to penicillin. Could this be a reason for worry ?
The answer to this hinges upon the question of why penicillin resistance is not more common in S. pyogenes. In the 1980's, there was an upsurge in reports describing penicillin tolerant S. pyogenes, but for one reason or other it didn't seem to stick.
This suggests that penicillin resistance may not have much sticking power in the streptococcal population, so probably we shouldn't be too worried.
However, we don't know why penicillin resistance was lost from the population of S. pyogenes the first time round, so we don't necessarily have any guarantee that we won't lose penicillin from our armoury against Streptococcus pyogenes.
Hsieh YC, &; Huang YC (2011). Scarlet fever outbreak in Hong Kong, 2011. Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi, 44 (6), 409-11 PMID: 21873124
Kahn F, & Rasmussen M (2012). Penicillin-resistant Streptococcus pyogenes? FEMS microbiology letters, 326 (1) PMID: 22092538
Ogawa, T., Terao, Y., Sakata, H., Okuni, H., Ninomiya, K., Ikebe, K., Maeda, Y., & Kawabata, S. (2011). Epidemiological characterization of Streptococcus pyogenes isolated from patients with multiple onsets of pharyngitis FEMS Microbiology Letters, 318 (2), 143-151 DOI: 10.1111/j.1574-6968.2011.02252.x![]()
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Outbreaks of S. pyogenes have been steadily increasing since the 1980's, in part due to the rise of more infectious serotypes.
This year, scarlet fever hit Hong Kong causing at least 600 new cases of this disease, and two fatalities, who were both children. The cause of this outbreak could be traced to two new strains of S. pyogenes, both of which acquired mutations that made them more virulent than others previously seen. The reasons that two separate strains decided to suddenly become superbugs at the same time is a subject for speculation. It is known that these strains had developed an increased resistance to erythromycin, probably obtained from commensal bacteria found in the oropharynx or the urogenital tract.
But this wasn't necessarily a cause for alarm. Whilst the increased resistance to erythromycin in these strains was worrying, it wasn't new. Erythromycin resistance has been seen in other strains, and is generally not prescribed to treat S. pyogenes. Unlike other pathogens, S.pyogenes has stubbornly remained vulnerable to penicillin.
“The fact that we still have penicillin is something we all get down on our knees and say prayers about each night.” is what Edward Kaplan, the elder statesman of streptococcal research had this to say of the Hong Kong outbreak. That only two children died from this outbreak is a testament to how far we've come medically since the early 20th century, and a testament to the success of penicillin.
However, a report from Japan suggests that this situation could be changing.
The researchers set out to explain recurrent episodes of streptococcal pharyngitis. When a patients get pharyngitis, after seemingly clearing infection, it is difficult for researchers to determine whether they were re-infected with S. pyogenes, or whether the S. pyogenes had somehow survived the treatment. With this study, the researchers wanted to answer this question once and for all.
So between the years of 2006-2008 they set up shop at the Asahikawa Kosei hospital. Whenever a patient presented with pharyngitis, the doctors at the hospital sent on a sample of the bacteria recovered fromt he patient on to the researchers for further analysis. The researchers would then serotype the strains, and work out what virulence factors they tend to produce, and what antibiotics they are resistant to. using this information allowed the researchers to identify individual strains of bacteria, and track how they spread through the community.
When a patient got an initial infection with S. pyogenes , the researchers got a sample of the bugs. If the infection recurs and the patient returns to hospital, the researchers got another sample from the same patient. So they could take the first sample, and compare it to the second sample to decide whether what had happened was a re-infection with a new strain of bacteria, or whether it was the same strain that they had before.
However, a nasty surprise awaited the researchers when they tested the bacteria for antibiotic resistance. They found two instances of S. pyogenes which showed resistance to penicillin. Could this be a reason for worry ?
The answer to this hinges upon the question of why penicillin resistance is not more common in S. pyogenes. In the 1980's, there was an upsurge in reports describing penicillin tolerant S. pyogenes, but for one reason or other it didn't seem to stick.
This suggests that penicillin resistance may not have much sticking power in the streptococcal population, so probably we shouldn't be too worried.
However, we don't know why penicillin resistance was lost from the population of S. pyogenes the first time round, so we don't necessarily have any guarantee that we won't lose penicillin from our armoury against Streptococcus pyogenes.
Hsieh YC, &; Huang YC (2011). Scarlet fever outbreak in Hong Kong, 2011. Journal of microbiology, immunology, and infection = Wei mian yu gan ran za zhi, 44 (6), 409-11 PMID: 21873124
Kahn F, & Rasmussen M (2012). Penicillin-resistant Streptococcus pyogenes? FEMS microbiology letters, 326 (1) PMID: 22092538
Ogawa, T., Terao, Y., Sakata, H., Okuni, H., Ninomiya, K., Ikebe, K., Maeda, Y., & Kawabata, S. (2011). Epidemiological characterization of Streptococcus pyogenes isolated from patients with multiple onsets of pharyngitis FEMS Microbiology Letters, 318 (2), 143-151 DOI: 10.1111/j.1574-6968.2011.02252.x
