[LoneWolf (OP)]

I'm at hospital with my dad who has developed a Bacteria Resistant infection beginning with am My. . .

Is this as serious as I think it is, can this kill him?

[CliffordK]

Multidrug resistant infections can often be dangerous to patients with compromised immune systems, although they frequently pose little danger to "healthy" individuals.

A few diseases beginning with "My".  There are related pathological diseases too.  Theses are genus of bacteria with many subspecies.

Mycoplasma including Mycoplasma Pneumoniae, an "atypical pneumonia" generally susceptible to antibiotics, but there may be some resistant strains.
Mycobacterium tuberculosis & Mycobacterium leprae.  TB is usually referred to as tuberculosis.  It is often a hard disease to treat, and drug resistance can be a problem. 

Anyway, there would be a lot of factors including the actual name of the disease, the general health of the patient, whether it is a lung disease, GI system, post trauma, skin, post surgical, or surgical implant colonization.

[cheryl j]

Sometimes with bacteria that are resistant to all antibiotics, they can combine two or more of these antibiotics and it will be effective. (I don't know why this works.) Other times there are newer antibiotics that doctors just have to get special permission to use. They are only used in these cases so that resistance to this drug does not develop in the general population as quickly.

[dlorde]

Sometimes with bacteria that are resistant to all antibiotics, they can combine two or more of these antibiotics and it will be effective. (I don't know why this works.)

It may be that some multi-drug resistant forms can withstand the metabolic load of dealing with any one antibiotic, but can't cope with two or more at once.

I understand that it's been found that combined antibiotic treatments are synergistic - the results are way better than you'd expect from summing each antibiotic's effectiveness, and I hear there have been recommendations to treat all non-trivial infections with combined antibiotics because this is not only much more effective, but significantly reduces the incidence of bacterial resistance developing, and allows the more powerful antibiotics and antibiotics 'of last resort' to be used much less frequently.

[cheryl j]

It just seemed strange to me that if bacteria have an enzyme (like say, beta lactamase)  that makes it resistant to a particular antibiotic, throwing another antibiotic,which it is also resistant to, would make any difference, but the concept of metabolic overload does kind of make sense, since the bacteria may not be able to manufacture multiple enzymes fast enough to prevent the antibiotics from damaging things like cell walls.

[CliffordK]

I think there are bacteria that are only partly resistant to certain treatments.  So, high doses of the antibiotics still will lead to some efficacy.

If the bacteria is not resistant, then multi-drug therapy gives two mechanisms for the bacteria to battle, and thus lower survival rate, and thus less development of resistance.  Or, if the pathogen isn't completely known, the multi-drug therapy can lead to broader spectrum coverage.