Table D1A. b -lactam-antibiotics and Enterobacteriaceae. 25.02.01 ks Primary sensitivity testing.(Søgaard P. 1988,Vedel G. & al. 1996 ks (L 15,16,25)F.species.html. D1.B-lactam.497.html AIM.html Maal.html Primaer.html 25.02.01 ks

Table D1A shows a simplified division according to b-lactamase-genotype.

Antibiotic

Ampicillin

Carboxipenicillins

Mecillinam

Cefuroxim

Cephalothin

Aztreonam

Group 1,Sensitive: E.coli

(65% of the species), Shigella,Salmonella,

P.mirabilis

Reading(Reply)

 

 

 

2-3 (I,S)

 

 

 

3 (S)

 

 

 

d

 

 

 

3 (S)

 

 

 

2-3 (I,S)

 

 

 

3 (S)

Group 2, Chromosomal Cephalosporinase producers

C.freundii, H.alvei, E.cloacae & aerogenes, P. vulgaris, Morganella, Serratia,Providencia, E.coli (5% of the species, AmpC)

 

 

 

0-1 (R)

 

 

 

3 (S)

 

 

 

3 (S)

 

 

 

3 (R)

 

 

 

0 (R)

 

 

 

3 (R)

Group 3, Chromosomal ampicillinase producers:

Klebsiella, C. koseri

 

0 (R)

 

0 (R)

 

3 (S)

 

3 (S)

 

3 (S)

 

3 (S)

Group 5, Episomal ampicillinase producers:

E.coli(30% of the species)

 

 

0 (R)

 

 

0 (R)

 

 

d

 

 

3 (S)

 

 

2-3 (I,S)

 

 

3 (S)

When the species belongs to group 1 or 3, sensitivity testing with ampicillin and cefuroxim is sufficient for characterization of the b -lactam genotype.

For the characterization of of the b -lactam genotypes of the species of groups 2 and 5, the sensitivity of the isolate to a weak cephalosporin and to a carboxi-penicillin has to be known, especially on account of the ampicillin-resistant strains of E. coli. Of these 1/7 or 5% of a total of 35% ampicillin-resistant strains, are resistant to cephalosporins. This is quantitatively important , but the correct reply of Enterobacter cloacæ as cephalosporin-resistant is the qualitatively most important reply..

 

For the correct treatrment of patients with bacteræmia, already the primary sensitivity testing should include an antibiotic from these two groups of antibiotics (v.s.). Kahlmeter, http://www.ltkronoberg.se/ext/raf/raf/htm , uses cefotaxim, piperacillin, and piperacillin+tazobactam in an analogous way. Alain Philippon, Hôpital Cochin, Paris 14, uses ticarcillin and cephalothin.