Letter Re: Antibiotics for Serious Wounds

A reader wrote to ask: “Dr. Koelker, you explained what each of the antibiotics is good for, but one major concern was unaddressed. In a TEOTWAWKI situation we may be faced with having to treat gunshot wounds. And just as likely, if not more so, we may need to treat serious lacerations, such as accidents with sharp, dirty tools. I think, as am I, the readers of this blog might be interested to know which antibiotics are the most effective in preventing infections if/when we sustain such wounds.”  

Doctor Koelker Replies:  As usual, such answers come in a short and a long form.  At the moment I won’t address details of wound cleansing, closing, cauterizing, likelihood of infection or fatality, etc., etc. 

Here is the short answer: The microbes that are likely to have been introduced into a wound determine the choice of both prophylactic and/or treatment antibiotics.  When antibiotics are given before a visible infection is apparent, the assumption is that the wound still contains bacteria in low numbers (most of which have hopefully been washed away by appropriate cleansing). Killing off these remaining microbes should prevent infection in most cases – although prophylactic treatment is not always effective.

Where do these germs come from?  This depends on the body part that was penetrated, the environment, and the source of the projectile.

Injuries that pierce the skin carry the risk of contamination from common skin microbes, primarily staph and strep germs.  When orthopedic surgeons place pins and screws in bones, they pierce the skin.  Despite careful antisepsis, perhaps a few bacteria might still be introduced into a bone, where infection can fester, causing permanent damage, limb loss, or even death.  Though in a surgical setting the risk of infection is low, the potential consequences of infection are so high that prophylactic antibiotics are standard – one dose before surgery, and one to several doses after surgery.  The intravenous antibiotic Ancef is most commonly employed (which is most similar to cephalexin, see below). 

Of the available oral antibiotics previously discussed, the best choices would be cephalexin, Augmentin, Avelox or Levaquin.  Less potent alternatives, if the former are unavailable, would include the erythromycins (including clarithromycin and azithromycin), tetracyclines (including doxycycline), or trimethoprim-sulfamethoxazole (TMP-SMX).  Amoxicillin, penicillin, and ciprofloxacin are much less likely to be effective.  Normally IV antibiotics are preferred due to their immediate bioavailability and high blood concentration.  If oral antibiotics are used pre-op, they should be given on an empty stomach with water only, about two hours prior to surgery.

The other large class of potential contaminants is that of intestinal bacteria, especially gram-negative bacteria and anaerobes.  If the source of contamination is external, as an explosion in a cesspool, a person might live without surgery.  If the source is perforation of one’s internal organs, death is likely without emergency surgery. 

But say surgery is an option, or you’ve cut your hand deeply while cleaning out a septic tank – you’ll probably need a combination of antibiotics to avoid or treat infection.  The first should be either ciprofloxacin, Levaquin, or Avelox, whichever is available (ciprofloxacin is the only inexpensive generic in this class).  Second line alternatives for these would be Augmentin or TMP-SMX.  Additionally, metronidazole should be added to cover anaerobic bacteria.  Basically, the same antibiotics useful for diverticulitis or other intra-abdominal infection are indicated for intra-abdominal wounds. 

Lastly, we seldom think of tetanus except to get vaccinated when we’re injured.  If you haven’t been immunized in the last five years, then do so now.  The new TDAP vaccine includes immunization against diphtheria and pertussis as well.  If a wound is deep or contaminated with rust, treating with metronidazole (or penicillin) may decrease the number of tetanus-toxin producing Clostridium tetani bacteria, but these antibiotics do nothing to counter the toxin that has been produced, and which may cause muscle spasms that constrict the airway.  Without immunization, risk of death is very high.   (Doctor Koelker is SurvivalBlog’s Medical Editor. She is also the editor of ArmageddonMedicine.net.)