Antibiotics 4

Amikacin is the best anti-Pseudomonal aminoglycoside that we have. However, the dose is higher, the recommended blood levels are higher and we usually recommend restricting this to treatment failures with tobramycin or Pseudomonas that is resistant to tobramycin because this may very well cost $20-30 per gram. It is significantly more expensive than the others of this group.

Neomycin is not given parenterally at all but it can sometimes be used topically. It’s an extremely nephro- and ototoxic drug. We do not suggest that high concentrations be used for extensive wound irrigation. I would add a caution here. Topical drugs are later and I don’t know that we will get a chance to talk about those. Neomycin is a fairly potent contact sensitizing agent. It’s commonly sold over the counter in antibiotic creams and ointments. Neosporin is a classic example. Neomycin polymyxin and, I believe, it’s bacitracin that’s contained in there. The bacitracin is like penicillin. It covers the Gram positives. Polymyxin and neomycin have essentially the same spectrum. There is no reason to need to use both of those drugs together. Neomycin increases the risk of contact allergic reactions.

The suggestion that I have is instead of recommending Neosporin, recommend the product that contains polymyxin and bacitracin which is Polysporin. It should be readily available. Unfortunately, it is a little more expensive than neosporin but it may save you some phone calls in the middle of the night or some hysterical people who have broken out in a rash.

Lastly, streptomycin is an aminoglycoside that may be used in combination therapy for tuberculosis occasionally and I’ve listed some information about the availability of that product.

Clindamycin is Cleocin. This is used primarily for anaerobic infections, principally of GI origin. It can also be used in the treatment of Staph. It’s used a lot in dental work, for example. Its problem is pseudomembranous colitis. This is C. difficile overgrowth. The treatment of choice here is either oral or IV metronidazole or Flagyl or oral vancomycin.

Now, in the past, the practice has been to use vancomycin first orally and then use metronidazole or Flagyl second. I would suggest the opposite. The current thinking is to use metronidazole or Flagyl as your drug of choice and go to vancomycin oral if you get a treatment failure. You probably will have a treatment failure about 10% of the time with either drug. However, a course of Flagyl is about $15 or $20. A course of vancomycin may very well be upwards to $200 or more and that’s the oral drug. It’s extremely expensive and it also tastes terrible.

Be aware too, and notice here, that IV Flagyl can be used for pseudomembranous colitis but IV vancomycin cannot. So if you have a patient that is NPO and develops pseudomembranous colitis, your drug of choice is IV Flagyl.

Vancomycin is a drug that we would use for methicillin resistant Staph aureus or for Staph epidermidis. It can be used orally but that is only for local effect on the gut. When it is used, it needs to be administered over at least an hour to cut down on the so-called “red neck” or “red man” syndrome. This is a syndrome of flushing and very often hypotension and dizziness that occurs when you run in vancomycin too quickly. You will find some people will not even tolerate an hour and you may have to go infuse it over two or three hours.

Used alone, this drug, frankly, is not particularly nephrotoxic although it got a wrap as being nephrotoxic when it was originally brought out some decades ago. However, when you start using other nephrotoxic drugs with it, watch out. If you are using vancomycin and you add gentamicin, watch out. Watch your renal function, watch your blood levels because you are probably going to have to change one or the other drug dosage to accommodate declining renal function. Usually it is reversible.

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