Haemophilus influenzae (yellow rods) growing on airway cells
(Image from the Science Museum archive)
Haemophilus influenzae: blood lover of influenza. Misnamed, as it doesn't actually cause influenza (flu). Flu is caused by a virus as many a public health campaign will have told you: antibiotics don't help! But it is a blood lover, requiring components of blood, ready broken down, for it to survive in the lab. Outside its normal environment (the back of your throat), it's a bit of a wimp. In its own habitat, it is a master of survival, usually harmless and just occasionally a cause of devastating disease: meningitis and blood poisoning. One of the least trumpeted and most quietly effective vaccines of the past 20 years, Hib, has seen potentially fatal Haemophilus disease all but eliminated from the UK's children. On the other hand, Haemophilus causes middle ear infections and infection-related worsening of chronic bronchitis; two troublesome conditions at opposite ends of life, causing misery to many, poor school performance in affected children and lots of healthcare visits and hospital admissions.
Haemophilus, as a result, is responsible for huge numbers of antibiotic prescriptions. Antibiotic resistance is becoming more common, so different antibiotics need to be used, so more resistance arises and so on.
It was the first free-living organism to have its genome (complete genetic code) sequenced, giving us a headstart on understanding its biology and providing the starting point for the massive growth in sequence information which has flooded the scientific world since.
Discovered in the 1890s and present in up to 75% of us at any one time, it is a bacterium which lacks headline appeal but has a lot to teach us about bacteria-human interaction and antibiotic resistance.
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