TRANSFER OF RESISTANCE TO OXY-IMINOCEPHALOSPORINS AND OF EXTENDED-SPECTRUM BETA-LACTAMASE PRODUCTIONS IN KLEBSIELLA-PNEUMONIAE STRAINS FROMINFECTED NEONATES

In this communication, we describe the occurrence of strains of Klebsi ella pneumoniae resistant to cephalosporins of all generations and to aztreonam due to their production of Extended Spectrum beta-Lactamases (ESBLs), in two hospitals in Slovakia. They were found to transfer th e genetic determinants of resistance to cefotaxime, ceftazidime and az treonam and of ESBL production to suitable recipient strains of Escher ichia coli K-12 No. 3110 and Proteus mirabilis P-38. Six donor K. pneu moniae strains were collected from six prematurely born babies gradual ly infected with strains of K. pneumoniae resistant to cefotaxime, cef tazidime and aztreonam. All six strains of K. pneumoniae gave an ident ical pattern in ESBL testing (double-disk diffusion test). The second cycle of transfers to nalidixin-resistant E. coli K-12 No. 185 nal+ al so confirmed that all transconjugants were resistant to all beta-lacta ms tested. We conclude that a single gene was transferred from donor s trains which confers 'en bloc' the resistance to the beta-lactams test ed. Four strains of K. pneumoniae produced a uniform type of ESBL alth ough with different quantitative expression. All transconjugants teste d produced identical types of ESBL as did the donor strains of K. pneu moniae. This transfer of an identical pattern of ESBL production was c onfirmed also in the second cycle of transfers. Cefotaxime, ceftazidim e and aztreonam were actively hydrolysed (as shown by the relative rat e of hydrolysis [Vmax]) by strains of K. pneumoniae as well as by tran sconjugant colonies and clavulanate inhibited the hydrolysis of these beta-lactam antibiotics.