Why do some minor superficial abrasions get infected by tetanus?

Question

Theoretically, since C Tetani is anaerobic, it should not be able to germinate in minor wounds, such as an abrasion, or shallow scratch.

But I’m reading that sometimes it does. Usually in older people, or people with diabetes. But it does happen to young people after minor abrasions for seemingly no reason that I can ascertain.

Superficial abrasions should be well oxygenated and thus prevent tetanus from manifesting after such a wound.

I also read that some conditions in the wound must be present for germination. Such as:

Deep, low oxygen environment.

Dead tissue.

Coinfection with another bacteria.

Foreign body contamination, such as dirt.

Localized ischemia (low blood supply).

This source says atleast two of these factors must be present along with no immunity from tetanus for it to cause tetanus.

So, I’m wondering, do all of these supposed “minor abrasions” described actually end up getting infected, or containing dead tissue? I’m not sure. A completely healthy abrasion shouldn’t be able to cause tetanus if none of these factors are present.

In: Biology

Answer 1

A minor abrasion can very easily hit two of those factors, such as having a foreign substance and other infecting bacteria in the wound. It is less as you mentioned and many of us are vaccinated for tetanus at some point, giving us some immunity.