Summary Chapter 11_ Antibacterial Drugs Resistance (Levinson 17th Ed)

Chapter 11: Antibacterial Drugs: Resistance




Reasons for Drug resistance?

1. Genetic change in the organism (chromosomal mutation, acquisition of a plasmid,
acquisition of a transposon)



High­Level Resistance: refers to resistance that cannot be overcome by increasing the dose of
the antibiotic.

Seen in ? resistance mediated by enzymes (eg β­lactamases)

Acquisition of plasmids carrying several genes that encode the enzymes that mediate resistance.

, Low Level Resistance: refers to resistance that can be overcome by increasing the dose of the
antibiotic.

Seen in ? Resistance mediated by mutations



More likely to be caused by antibiotic ­resistant organisms:

HAP > CAP



Two types of resistant gram­negative rods are especially important in hospital acquired
infection:

Multidrug resistant (MDR) gram negative rods ->

produce beta lactamases that inactivate penicillins, cephalosporins, and carbapenems.

Extended spectrum beta lactamase (ESBL) producing gram negative rods ->

produce beta lactamases that inactivate second, third, and fourth generation cephalosporins.