Enterobacter cloacae resistant to third generation cephalosporins emerged rapidly during an outbreak of serious infections due to this organism in a neonatal intensive care unit where ampicillin and gentamicin were used as first line antibiotic treatment. Organisms resistant to cephalosporins were isolated from 12 infants, six of whom developed systemic infection. Two infants died. Isolates of ...

The in vitro activity of cephalexin, cephaloridine, cephalothin, cephapirin, cefoxitin, cephamycin C, cepharadine and cefazolin was determined against 443 isolates of bacteria. At a concentration of 12.5 mug/ml, all of the cephalosporins inhibited more than 60% of the isolates of Klebsiella pneumoniae. At the same concentration, cephalexin, cephaloridine, cephalothin, cephapirin, cephamycin C a...

A 10% cross-reactivity rate is commonly cited between penicillins and cephalosporins. However, this figure originated from studies in the 1960s and 1970s which included first-generation cephalosporins with similar side-chains to penicillins. Cephalosporins were frequently contaminated by trace amount of penicillins at that time. The side-chain hypothesis for beta-lactam hypersensitivity is supp...

OBJECTIVES In Neisseria gonorrhoeae, the mosaic structure of penicillin-binding protein 2 (PBP 2), composed of fragments of PBP 2 from Neisseria cinerea and Neisseria perflava, was significantly associated with decreased susceptibility to cephalosporins, particularly oral cephalosporins. The aim of this study was to determine the affinity of mosaic PBP 2 for cephalosporins in N. gonorrhoeae. ...

When disks containing cefuroxime (CXM) or HR 756 (756) were placed next to cefoxitin (FOX) on plates inoculated with Enterobacter resistant to FOX, there was marked flattening of the zones of inhibition produced by CXM or 756, but colonies growing near the CXM or 756 disks were found to be fully susceptible to these drugs on retesting. In contrast, when a checkerboard titration with CXM or 756 ...

The sensitivity of 127 strains of miscellaneous Gram-negative bacilli to various cephalosporins was determined by three methods. Disc tests with cephaloridine (CLOR), cephalothin (CTIN) and cephalexin (CLEX) made most strains of beta-lactamase-producing Escherichia coli appear sensitive. Eight cephalosporins were tested by the agar break-point method using concentrations of 16 and 4 mg/l for al...

BACKGROUND AND OBJECTIVE 13-Lactams are the most commonly used antibiotics but they can cause hypersensitivity reactions. We sought to estimate cross-reactivity and tolerability of cephalosporins in patients with cell-mediated allergy to penicillins. METHODS We studied 97 patients with a clinical history of nonimmediate reactions to a penicillin and a positive patch test result to at least 1 ...

Resemblances and differences between the penicillins (I) and cephalosporins (II) are considered from a chemical and biochemical point of view.

Introduction Cephalosporins are beta-lactam antimicrobials that share mechanisms of action and a similar structure with penicillins (Figure). Penicillins and cephalosporins have the same four-member “core” beta-lactam ring, but cephalosporins have an additional atom in the side ring. Modified side chains on either ring alter antimicrobial activity, resistance to beta-lactamases, or pharmacokine...

The validity of the class representative concept for in vitro susceptibility testing of older cephalosporins was reevaluated. Two oral cephalosporins, cephalexin and cefaclor, were compared with the established cephalosporin class representative, cephalothin, by using reference microdilution minimal inhibitory concentrations of 528 isolates of a wide variety of gram-positive and gram-negative b...