New antibiotics needed: Streptococcus pneumoniae
Posted on November 22, 2019 by Matt Bassett
As part of World Antibiotic Awareness Week, we are continuing our New Antibiotics Needed blog series detailing the twelve pathogens thought by the World Health Organisation (WHO) to pose the greatest threat to human health. Next on the list is Streptococcus pneumoniae.
Streptococcus pneumoniae
S. pneumoniae was first isolated by both George Sternberg and Louis Pasteur in 1881. Alexander Fleming discovered penicillin in 1928 and by 1942 it was being used to treat infections. In his Nobel Prize acceptance speech, Fleming warned about the possibility of bacteria developing immunity to penicillin. It took just two decades before clinical isolates of S. pneumoniae that were non-susceptible to penicillin were recorded. These strains are now common worldwide. The Centers for Disease Control and Prevention estimate that antibiotic resistant strains of S. pneumoniae cause 1.2 million infections in the USA every year, resulting in 7000 deaths annually.
In healthy individuals, S. pneumoniae live as commensals – a relationship where the bacteria benefit but the host is unaffected – in and around the nose, sinuses and respiratory tract, particularly in young children. In those with weakened immune systems, like the elderly and young children, the bacteria can become pathogenic and cause disease. Infections caused by S. pneumoniae are the cause of substantial antibiotic consumption in children; the bacteria are one of the main causes of acute otitis media – inflammation in the middle ear and associated ear infection – which effects 80% of children under three years old.
S. pneumoniae causes a variety of diseases; if the bacteria colonise the alveolus, the body’s inflammatory response causes plasma, blood and white blood cells to fill the alveoli, causing pneumonia. S. pneumoniae is the leading cause of community-driven pneumonia – pneumonia contracted by a person with no, or little, contact with a hospital. As well as pneumonia, S. pneumoniae can cause meningitis and, in extreme cases, sepsis.
Vaccines to the Rescue?
To help with the fight against growing antibiotic resistance in S. pneumoniae, vaccines have been developed, the first of which was developed in the 1980s. It was hoped that the vaccines would cause a significant, sustained reduction in antibiotic resistance. However, genomic analysis showed that although there was an initial dip in disease caused by antibiotic resistant strains of S. pneumoniae, this was only temporary.
Genomic surveillance has been vital in understanding the impact of the vaccines, and many countries are now routinely performing whole-genome sequencing for vaccine surveillance. Scientists are hoping genomics will play a vital role in the evaluation of new vaccines and treatments that may be used to reduce disease caused by antibiotic resistant strains of S. pneumoniae.
Genomic epidemiology of penicillin-non-susceptible Streptococcus pneumoniae is part of the New Antibiotics Needed collection in Microbial Genomics. Written by Tamsin Dewe, Joshua D’Aeth and Nicholas Croucher. The review highlights the role of genomics in improving our understanding of how penicillin-non-susceptible S. pneumoniae evolved, enhancing our ability to trace their transmission and developing new methods of predicting how pneumococci will respond to treatment with different forms of penicillin.