Segatore B, Massidda O, Satta G, Setacci D, Amicosante G
Department of Biomedical Sciences and Technologies and of Biometrics, Faculty of Medicine, University of L'Aquila, Italy.
Antimicrob Agents Chemother. 1993 Jun;37(6):1324-8. doi: 10.1128/AAC.37.6.1324.
The Aeromonas hydrophila AE036 chromosome contains a cphA gene encoding a metallo-beta-lactamase highly active against carbapenem antibiotics. This enzyme was induced in strain AE036 to the same extent by both benzylpenicillin and imipenem. When the cphA gene was inserted into plasmid pACYC184, used to transform Escherichia coli DH5 alpha, the MICs of imipenem, meropenem, and penem HRE664 for recombinant clone DH5 alpha(pAA20R), expressing the Aeromonas metallo-beta-lactamase, were significantly increased, but those of penicillins and cephalosporins were not. When the metallo-beta-lactamase purified from E. coli DH5 alpha(pAA20R) was assayed with several beta-lactam substrates, it hydrolyzed carbapenems but not penicillins or cephalosporins efficiently. These results demonstrate that this metallo-beta-lactamase possesses an unusual spectrum of activity compared with all the other class B enzymes identified so far, being active on penems and carbapenems only. This enzyme may thus contribute to the development of resistance to penems and carbapenems but not other beta-lactams.
嗜水气单胞菌AE036染色体含有一个cphA基因，该基因编码一种对碳青霉烯类抗生素具有高活性的金属β-内酰胺酶。在菌株AE036中，苄青霉素和亚胺培南对这种酶的诱导程度相同。当将cphA基因插入用于转化大肠杆菌DH5α的质粒pACYC184中时，表达嗜水气单胞菌金属β-内酰胺酶的重组克隆DH5α(pAA20R)对亚胺培南、美罗培南和青霉烯HRE664的最低抑菌浓度显著增加，但对青霉素和头孢菌素的最低抑菌浓度没有增加。当用几种β-内酰胺底物对从大肠杆菌DH5α(pAA20R)中纯化的金属β-内酰胺酶进行检测时，它能有效水解碳青霉烯类，但不能有效水解青霉素或头孢菌素。这些结果表明，与迄今鉴定的所有其他B类酶相比，这种金属β-内酰胺酶具有不同寻常的活性谱，仅对青霉烯类和碳青霉烯类有活性。因此，这种酶可能导致对青霉烯类和碳青霉烯类产生耐药性，但不会导致对其他β-内酰胺类产生耐药性。
