Resistant hospital germs developed in the USA: An international team of researchers analyzed the worldwide spread of the antibiotic-resistant hospital germ Clostridium difficile (C. difficile) and traced its origin back to North America. Infections with resistant Clostridium difficile hospital germs have become "the leading cause of antibiotic-associated diarrhea worldwide" in the past ten years, the researchers report in the journal "Nature Genetics".
In recent years, two strains of antibiotic-resistant Clostridium difficile have spread to clinics around the world with alarming speed, according to the scientists led by Miao He from the Wellcome Trust Sanger Institute in Cambridge, UK. Due to the resistance, the severe diarrheal diseases caused by Clostridium difficile can hardly or only to a limited extent be treated. For example, C. difficile in hospitals and old people's homes is the main cause of diarrheal diseases that are sometimes life-threatening. In the past few years, the bacteria had led to massive outbreaks in European and North American clinics. Where the pathogens come from and how they spread has so far remained unclear. The particularly heavy waves of infection were often triggered by variants of the aggressive genotype 027 / BI / NAP1, whereby the pathogens were resistant to the antibiotic class of fluoroquinolones, the scientists write in the journal "Nature Genetics".
Two lines of antibiotic-resistant hospital germs developed in parallel The genome researchers now came to the conclusion that two resistant strains of the common hospital germ Clostridium difficile developed in North America almost simultaneously. Afterwards, the germs spread rapidly in the global health system, Miao He and colleagues continued. The development of resistance was probably favored by the massive, partly negligent, use of antibiotics. After their emergence, the two resistant C. difficile strains spread on different routes in North America, Great Britain, Continental Europe and Australia, the scientists report. In the individual countries, massive nosocomial infections (hospital infections) and correspondingly severe disease waves were not uncommon.
More than 300 samples of the hospital germ Clostridium difficile analyzed The genome researchers around Miao He tracked the origin of the new resistant bacterial strains based on 151 germ samples, which were isolated in clinics worldwide between 1985 and 2010, and a further 188 samples from Great Britain. The scientists created a family tree of the pathogens based on the changes in the genetic material. They surprisingly found that two resistant C. difficile strains developed independently of one another in the United States at almost the same time. The two resistant lines of the genotype, which are immune to fluoroquinolones, emerged more or less in parallel. So far, the experts assumed that there was only an antibiotic-resistant line of the hospital germ.
Resistance due to excessive use of antibiotics According to the researchers, about ten years ago the first antibiotic-resistant C. difficile line, FQR1, was created in the USA. Within a few years, the hospital germ in the clinics of several states triggered severe waves of infection and was then imported to South Korea and Switzerland. The second antibiotic-resistant line, FQR2, also developed, according to genome researchers, probably in North America, but spread from here to Great Britain, Australia and via at least four separate routes to continental Europe. The scientists suspect the excessive use of antibiotics as the cause of the parallel emergence of the two antibiotic-resistant germ lines. Fluoroquinolones were the most commonly prescribed antibiotics in North America in the late 1990s and early 2000s, which increased the selection pressure on the germs so that two resistant C. difficile variants developed in parallel and then spread quickly.
Symptoms of Clostridium difficile infection Typical signs of C. difficile infection are diarrhea, abdominal pain, intestinal inflammation and fever. In the worst case, the pathogens' toxins lead to a life-threatening breakdown of the intestinal walls, after which the bacteria can spread throughout the organism and cause blood poisoning (sepsis). In this case, there is an acute danger to life for the patient. (fp)
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Picture: Dr. Karl Herrmann / pixelio.de