Fatima H. M'Zali

Three Cefotaximases, CTX-M-9, CTX-M-13, and CTX-M-14, among Enterobacteriaceae in the People's Republic of China

ABSTRACT Of 15 extended-spectrum β-lactamase (ESBL)-producing isolates of the family Enterobacteriaceae collected from the First Municipal Peoples Hospital of Guangzhou, in the southern part of the Peoples Republic of China, 9 were found to produce CTX-M ESBLs, 3 produced SHV-12, and 3 produced both CTX-M and SHV-12. Eleven isolates produced either TEM-1B or SHV-11, in addition to an ESBL. Nucleotide sequence analysis of the 12 isolates carrying blaCTX-M genes revealed that they harbored three different blaCTX-M genes, blaCTX-M-9 (5 isolates), blaCTX-M-13 (1 isolate), and blaCTX-M-14 (6 isolates). These genes have 98% nucleotide homology with blaToho-2. The blaCTX-M genes were carried on plasmids that ranged in size from 35 to 150 kb. Plasmid fingerprints and pulsed-field gel electrophoresis showed the dissemination of the blaCTX-M genes through transfer of different antibiotic resistance plasmids to different bacteria, suggesting that these resistance determinants are highly mobile. Insertion sequence ISEcp1, found on the upstream region of these genes, may be involved in the translocation of the blaCTX-M genes. This is the first report of the occurrence of SHV-12 and CTX-M ESBLs in China. The presence of strains with these ESBLs shows both the evolution of blaCTX-M genes and their dissemination among at least three species of the family Enterobacteriaceae, Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae, isolated within a single hospital. The predominance of CTX-M type enzymes seen in this area of China appears to be similar to that seen in South America but is different from those seen in Europe and North America, suggesting different evolutionary routes and selective pressures. A more comprehensive survey of the ESBL types from China is urgently needed.

NDM-1-Producing Klebsiella pneumoniae Resistant to Colistin in a French Community Patient without History of Foreign Travel

ABSTRACT A carbapenem-resistant Klebsiella pneumoniae strain, Kp5196, was responsible for an uncomplicated cystitis in a patient living at home and without history of foreign travel. This isolate produced the metallocarbapenemase NDM-1 and was resistant to all antibiotics except tetracyclines and colistin. The K. pneumoniae strain belonged to sequence type ST15, and blaNDM-1 was carried by a nontypeable conjugative plasmid. Two months later, a similar ST15 isolate, Kp5241, was present in the patient but was additionally colistin resistant.

blaIMP-9 and Its Association with Large Plasmids Carried by Pseudomonas aeruginosa Isolates from the People's Republic of China

ABSTRACT A novel plasmid-mediated metallo-β-lactamase (IMP-9) is described in seven isolates of Pseudomonas aeruginosa from Guangzhou, China, isolated in 2000. The gene was carried on a large (∼450-kb) IncP-2 conjugative plasmid. This is the first report of carriage of blaIMP genes on such large plasmids.

Discrimination of SHV β-Lactamase Genes by Restriction Site Insertion-PCR

ABSTRACT Restriction site insertion-PCR (RSI-PCR) is a simple, rapid technique for detection of point mutations. This technique exploits primers with one to three base mismatches near the 3′ end to modulate a restriction site. We have developed this technique to identify described mutations of the blaSHV genes for differentiation of SHV variants that cannot be distinguished easily by other techniques. To validate this method, eight standard strains were used, each producing a different SHV β-lactamase: SHV-1, SHV-2, SHV-3, SHV-4, SHV-5, SHV-6, SHV-8, and SHV-18. Mismatch primers were designed to detect mutations affecting amino acids at positions 8 (SspI), 179 (HinfI), 205 (PstI), 238 (Gly→Ala) (BsrI), and 240 (NruI) ofblaSHV genes. All amplimers of theblaSHV genes used in this study yielded the predicted restriction endonuclease digestion products. In addition, this study also makes theoretical identification ofblaSHV-6, blaSHV-8, and 12 novel blaSHV variants using the PCR-restriction fragment length polymorphism (RFLP) technique possible. By using a combination of PCR-RFLP and RSI-PCR techniques, up to 27 SHV variants can now be distinguished rapidly and reliably. These simple techniques are readily applied to epidemiological studies of the SHV β-lactamases and may be extended to the characterisation of other resistance determinants.