What I am saying is that from what I've read and heard on the subject there are
likely to be
multiple causes for cotton fever and also - my main point - that it is not considered a true infection per se but an acute sepsis-mimicking condition, a sort of disproportionate immune response. There is at least one case report where "cotton fever" has been attributed to an endotoxin produced by Enterobacter agglomerans as I mentioned above, but there are case reports where there was no evidence that this was the case (negative blood tests etc). After that one case was deemed to be caused by the specific endotoxin the report theorized that this could be the cause in
all cases and that some hospitals must have just missed the endotoxin because endotoxin might be harder to detect than the levels of bacteria needed to cause sepsis (infection). That is the reference Heroin Helper used to draw his own conclusions from. I wasn't saying it's caused simply by injecting a physical strand of cotton fiber (I am inclined to agree with Heroin Helper's assumption that it's possible that injecting a piece of cotton might just be a delivery system for the bacteria endotoxin. Regardless, injecting fibers or particles is unwise due to risk of embolism etc).
I think the problems are that since cotton fever usually resolves on its own and is experienced by IV drug users who rarely want to seek medical help if not necessary for obvious reasons, and that if/when they do it's very possible that the cases are not being reported and not much testing is being done. Doctors might just send someone home with some antibiotics. So the phenomenon has been poorly studied and there aren't a lot of good sources on the topic.
However, people have had this reaction from injecting drugs that were not filtered with cotton, which is why I think it's likely that it can happen due to things other than the endotoxin of the bacteria that can live on cotton. So my broad statement is that it is due to contamination
of some kind (which we can assume because injecting the same drugs under sterile conditions in a medical setting has never been reported to cause this kind of reaction to my knowledge). But it's
possible that all the cases could be due to an endotoxin of some type (maybe more kinds than just the one from Enterobacter agglomerans).
I was just trying to clarify that it's not correct to say "cotton fever is just a bacterial infection". Saying it's likely due to a mild case of endotoxemia or due to injecting
lipopolysaccharides would be more correct if we are going to go on the assumption that that is the sole cause. You wouldn't even necessarily have to inject any whole bacteria and the bacteria would not have to be alive. This is different from a bacterial infection.
(EDIT: Sorry this is so long! and getting out of BDD territory! Just trying to be clear)