malinda
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drug of choice for otitis media in infant is amoxicillin.If refractory,then use cefaclor that covers H influenza and strept pneumonia causes of otitis media too....My q is that if one is refractory to penicillin,wont he be refractory to cephalosporins too?Is there a diff between resistance,allergic and refractory?
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| vallia
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resistance and allergic reaction are different notions. The mechanism of bacterial resistance to B lactam antibiotics
1.distruction of beta lactam ring by beta lactamase
2.altered affinity of antibiotic for their target site(penicilin binding proteins)
3. decreased penetration of antibiotic to the target site, the pbs (only for gram negative bacteria
the cephalosporins have an" improved" structure , the side chains modification of the cephem nucleus confers an improved spectrum of antibacterial activity.
given the structural similarity of pennicilin and cephalosporins, aprox 1-7 % of the patients allergic to peniclin will be allergic to cephalosporins also. Cephalosporins is avoided in patients with immediate allergic reaction( anaphylaxis, bronchospassm, hypotension)
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| bactitech
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This is from a 2001 article on www.medscape.com:
http://www.medscape.com/viewarticle/412859_1
"Antibiotics are prescribed for AOM because they hasten resolution of symptoms and prevent infectious complications. As the 3 major bacterial pathogens, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, have become resistant to commonly prescribed oral antibiotics, management of AOM has become more difficult. The major challenge faced by clinicians in the 1990s has been the increase of drug-resistant S pneumoniae. Many strains of S pneumoniae are resistant not only to beta-lactams (penicillins and cephalosporins), but often to macrolides (eg, erythromycin) and trimethoprim-sulfamethoxazole as well. Furthermore, many strains of H influenzae and almost all strains of M catarrhalis produce beta-lactamase enzymes that hydrolyze penicillins and some cephalosporins. Nowadays, some antibiotics that are active against beta-lactamase-producing pathogens have poor activity against resistant S pneumoniae and vice-versa. Of the available antibiotics, few remain active against all or even the majority of pathogens, making empiric therapy difficult. Knowledge about the bacteriologic efficacy of the various available antibiotics has become more important than ever."
We see extremely resistant bacteria from cases of otitis media nowadays, especially from kids who are in daycare. S. pneumoniae is frequently resistant to amoxicillin. The article cited above has ten case histories. If you are going to go into family practice or pediatrics, it would behoove you to print out this article and read it in depth. The information is already five years old. The bacteria have only gotten more resistant in that period of time.
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