Originally Posted by WuWei
<snip>There is no "rule" or "obligation" to continue an UNNECESSARY antibiotic "once started". That just *further* sensitizes bacteria to the antibiotic, INCREASING the risk of developing antibiotic-resistant bacteria in your child, or in your own gut.
With respect, this is innacurate. Bacteria do not become "sensitized" to antibiotics. They are either incompletely or completely susceptible to the antibiotic or they are not. Antibiotic resistance occurs when a population of bacteria are incompletely killed by an incomplete course of antibiotics.
Just like any population, there are bacteria in any given bacterial population that are more susceptible to an abx than others. When you start a course of antibiotics, the most susceptible are killed off first and the less susceptible take longer. If you do not take the antibiotic long enough to kill the less susceptible, those are left at the end of the treatment. These grow and produce a new population of less susceptible bacteria. One or two may develop complete resistance and this complete resistance can be transfered by a variety of ways (plasmid transfer etc) so that the entire population is now resistant to the drug.
Completing a full course of antibiotics does not increase the chances of microbial resistance.
I do agree that if a particular antibiotic is making an individual very ill and it has been determined that the abx was not necessary in the first place, it may be beneficial to stop taking the drug. The pros and cons of this must be carefully weighed before proceeding though.
OP, I hope your baby makes a speedy recovery. In a child that young, I would not hesitate to give antibiotics for confirmed pneumonia.
ETA: In terms of pneumonia, it's usually not ever a choice between antibiotic A and antibiotic B and only one or the other will work. Generally a broad spectrum antibiotic that covers most causative agents implicated in bacterial pneumonia it the first course of treatment. IF the infection does not respond to the broad spectrum, a swab/sputum sample etc. will be taken and a more specific causative agent will be determined if possible. In this case, a more specific antibiotic may be used.