What genes are responsible for extended-spectrum cephalosporin resistance?

Extended-spectrum cephalosporin resistance is primarily associated with specific types of beta-lactamase enzymes that can hydrolyze these antibiotics. Among these, AmpC beta-lactamases and extended-spectrum beta-lactamases (ESBLs) are particularly significant.

AmpC beta-lactamases are a type of enzyme that can degrade a wide range of beta-lactam antibiotics, including the cephalosporins, and are often chromosomally encoded. In certain bacteria, the expression of these enzymes can lead to resistance to not just extended-spectrum cephalosporins but also other classes of antibiotics.

On the other hand, ESBLs, which include types like TEM, SHV, and CTX-M, are plasmid-encoded enzymes that also confer resistance to extended-spectrum cephalosporins. These enzymes can rapidly spread between different bacteria, thus increasing the challenge of managing infections caused by multidrug-resistant organisms.

The other options do not account for the primary mechanisms involved in extended-spectrum cephalosporin resistance. MRSA genes focus on methicillin resistance and are not directly involved in cephalosporins. VRE genes are associated with vancomycin resistance, irrelevant to ceph