With at least nine children confirmed dead from severe strep A infections in England, the government has raised the strategy of preventive antibiotics, where penicillin is given to close contacts to prevent them from falling ill. But what is the plan, and what difference will it make?
Why is the government considering preventive antibiotics?
Most group A streptococcal infections are minor, but on rare occasions the bacterium can find its way into the blood stream, tissues and organs, causing what is called invasive Group A strep, or iGAS disease. These infections can lead to severe illness, including potentially lethal sepsis and toxic shock.
Public health guidelines drawn up more than a decade ago state that close contacts of iGAS cases can receive prophylactic antibiotics for 10 days if there are two or more cases in a household or an institutional setting such as a nursing home or school. “This has been established practice for some time,” says Adam Finn, professor of paediatrics at the Bristol Royal hospital for children. “You give close contacts antibiotics in an attempt to shut down secondary cases.” Some countries have a lower bar to dishing out preventive antibiotics. Canada, for example, offers prophylactic penicillin to close contacts during outbreaks of scarlet fever, also caused by strep A.
Has this been done before?
Yes, but it’s not common. If there is an outbreak of iGAS in a school, a local outbreak team will go in, identify close contacts of known cases and offer them a 10-day course of penicillin. At the end of November, health officials offered antibiotics to all staff and the pupils in Years 1 and 2 at Ashford Church of England primary school after a six-year-old child died of an iGAS infection. Depending on the situation, classes, year groups and entire nurseries can be offered penicillin if cases of iGAS are confirmed.
Does it work?
Penicillin is highly effective against strep A infections. What is less clear is how effective preventive antibiotics are at reducing the number of severe invasive infections that arise from contact with a known case. An analysis of UK data found that 2,000 close contacts would need to receive prophylactic antibiotics to prevent a single subsequent case of iGAS disease. Part of the reason is that iGAS is rare – many secondary cases will be milder, non-invasive infections.
What about antibiotic resistance?
Antibiotic resistance happens when bacteria evolve so that they are no longer killed by antibiotics. Doctors are not worried about strep A developing resistance to penicillin, because the bug seems incapable of withstanding the drug. There would be concerns if penicillin were handed out en masse, as this would drive the emergence of resistant strains of other bacteria, but there will be no blanket prescription of preventive antibiotics.
Is this a viable long-term solution?
Handing out preventive antibiotics is a short-term intervention, aimed at closing down specific outbreaks. While strep A infections have risen early this year, and the UK has seen more infections than usual, they are expected to fall back down in the coming weeks and months. “Generally speaking, we’ll see a cluster of cases over one, two or three months and it stops again,” says Finn. “This has happened earlier than we usually see in the winter season, so it might go on for longer, but it will die down.”
What if there is a penicillin shortage?
The National Pharmacy Association has warned of “blips” in the supply chain of liquid penicillin, which is often given to children. But while brief, local shortages of antibiotics are possible, stocks can be moved around from depot to depot to even out supply. Penicillin is not the only antibiotic that is effective against strep A; it is merely the antibiotic of choice. “We’ve got a whole bunch of other antibiotics that kill Group A strep. We just like to give the simplest and cheapest antibiotic that is least likely to cause antibiotic resistance,” says Finn. “I don’t think there’s any prospect at all of anyone with an infection that needs treatment not getting treatment.”
