Thin end of the wedge?

The emergence of extremely drug resistant bacteria could prove to be the first of many.

In the last week, two publications have appeared in the press describing the worrying emergence of bacteria that are resistant to many of the drugs we normally use to treat such infections. A lot has been written in the last few years regarding the threat of antimicrobial resistant infections, but it is clear, the more we look for these infections, the more we find them and the more dynamic the organisms causing them appear to be. Drug resistant infections are a global problem and the movement of people around the world can lead to the dissemination of drug resistant bacteria and both of these reports highlight this as a problem.

The first report was In the USA Centre for Disease Control and Prevention in their ‘Morbidity and Mortality Weekly Report’, which was described widely in the press (Daily Mail, The Independent and the BBC Website).

The report indicates that the patient contracted a strain of a bacterium called Klebsiella pneumoniae which resulted in sepsis and death. The bacterium that caused the infection was resistant to all available antibiotics used to treat systemic infections in the USA (26 different drugs), although it was sensitive to an antibiotic called fosfomycin – this drug is not licensed in the USA for delivery via injection into the bloodstream (intravenous delivery). In several countries in Europe (including the UK) fosfomycin is licensed for intravenous use in cases such as this. This is important because we are seeing increasing numbers of drug resistant infections and this is one of the first cases for Klebsiella where no drug options were open to the medical staff. The report also highlights that appropriate infection control measures, such as testing the drug susceptibility of the bacteria causing the infection, isolation of patients and good knowledge of previous medical history, are vital for slowing the spread of drug resistant infections.

The second report in the Daily Mail described a study published in the US journal Proceedings of the National Academy of Sciences that took an innovate approach to trying to understand the spread of a group of bacteria known as carbapenem resistant Enterobacteriaceae (CRE). The researchers, led by Bill Hanage at the Harvard University Chan School of Public Health, found that CRE are much more widespread, are much more diverse than previously thought and can be transmitted from person-to-person without causing disease – something often referred to as asymptomatic carriage. The researchers used very detailed analysis of the genomes of many bacteria isolated from the Boston area and also in California to come to their conclusions. Significantly, the majority of studies normally focus on treating infections and profiling the bacteria that caused those infections. This study however showed that these bacteria are in the community and tried to characterise the bacteria that are being passed from person to person, without causing disease. This is important as many bacteria are opportunistic, they cause disease in patients that may have other underlying medical conditions. If these opportunistic bacterial infections are drug resistant, then this can present a significant challenge to doctors and how they treat the infection (See the case discussed above). Worryingly, the researchers also identified new kinds of drug resistance in these bacteria, suggesting that there are more antimicrobial resistant bacteria and ways to be resistant out there and yet to be discovered.

Both of these studies were accurately reported in the press and highlight the real danger that antimicrobial resistant infections pose on a global scale. The silent spreading of drug resistant bacteria in the community may also be a bigger problem than previously appreciated suggesting that we need to increase surveillance and be vigilant during outbreaks.