oa Southern African Journal of Infectious Diseases - NDM-1, novel TEM-205, novel TEM-213 and other extended-spectrum β-lactamases co-expressed in isolates from cystic fibrosis patients from South Africa : research
Background: β-lactamase-mediated resistance was investigated in isolates from cystic fibrosis (CF) patients attending clinics in the public and private health sectors in Durban, South Africa.
Method: Fifteen Pseudomonas aeruginosa, two Enterobacter cloacae and one each of Klebsiella pneumoniae, Burkholderia cepacia complex and Stenotrophomonas maltophilia, were subjected to minimum inhibitory concentration determination, PCR and sequencing for blaTEM, blaSHV, blaCTX-M, blaCMY, blaPER, blaVEB,, blaOXA, blaKPC, blaGES, blaIMP, blaVIM and blaNDM genes.
Results: All but one isolate carried multiple β-lactamases from two or more different Ambler classes. Novel Temoneira-205 (TEM- 205) (GenBank Accession No. KC900516) was found in a single isolate in combination with New Delhi metallo-β-lactamase-1 (NDM-1), reported for the first time in P. aeruginosa in South Africa. TEM-205 showed five amino acid changes compared with TEM-1 viz. V84I, E104 K, R164S, M182T and A184 V, while novel TEM-213 (GenBank Accession No. KC663615), identified in three isolates, showed a single amino acid change, Y105F. Resistance phenotypes did not routinely correlate with the genotypes. This is the first report of NDM-1 from B. cepacia complex in South Africa.
Conclusion: The co-expression and/or co-carriage of Ambler classes A, B and C β-lactamases in various permutations in single isolates severely restricts the clinical management of CF, not only with β-lactam antibiotics, but also with aminoglycosides and fluoroquinolones, the resistance genes of which commonly occur on the same genetic determinants of resistance. The presence of NDM-1, in combination with the Cephamycins (CMY) class C/AmpC β-lactamases, TEM, sulfhydryl-variable (SHV) and cefotaximase-M (CTX-M) extended-spectrum β-lactamases, is of grave concern, leaving colistin as the sole remaining treatment option for this pathogen.
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