Bacteremia Due to Extended-Spectrum- -Lactamase-Producing Aeromonas spp. at a Medical Center in Southern Taiwan

Department of Internal Medicine, National Cheng Kung University Medical College and Hospital, Tainan, Taiwan.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 10/2011; 55(12):5813-8. DOI: 10.1128/AAC.00634-11
Source: PubMed


Although extended-spectrum-β-lactamase (ESBL)-producing aeromonads have been increasingly reported in recent years, most of
them were isolates from case reports or environmental isolates. To investigate the prevalence of ESBL producers among Aeromonas blood isolates and the genes encoding ESBLs, consecutive nonduplicate Aeromonas blood isolates collected at a medical center in southern Taiwan from March 2004 to December 2008 were studied. The ESBL phenotypes
were examined by clavulanate combination disk test and the cefepime-clavulanate ESBL Etest. The presence of ESBL-encoding
genes, including blaTEM, blaPER, blaCTX-M, and blaSHV genes, was evaluated by PCR and sequence analysis. The results showed that 4 (2.6%) of 156 Aeromonas blood isolates, 1 Aeromonas hydrophila isolate and 3 Aeromonas caviae isolates, expressed an ESBL-producing phenotype. The ESBL gene in two A. caviae isolates was blaPER-3, which was located in both chromosomes and plasmids, as demonstrated by Southern hybridization. Of four patients with ESBL-producing
Aeromonas bacteremia, two presented with catheter-related phlebitis and the other two with primary bacteremia. Three patients had been
treated with initial noncarbapenem β-lactams for 5 to 10 days, and all survived. In conclusion, ESBL producers exist among
Aeromonas blood isolates, and clinical suspicion of ESBL production should be raised in treating infections due to cefotaxime-resistant
Aeromonas isolates.

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Available from: Wen-Chien Ko
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    • "Importantly, all these isolates were susceptible to carbapenems (including imipenem, meropenem, and ertapenem) and the aminoglycoside (amikacin) generally used for ESBL-producing E. coli treatment. ESBL-encoding genes were identified using specific primers for the blaTEM, blaSHV, and blaCTX-M genes, previously described (Jiang et al., 2006; Wu et al., 2011), followed by DNA sequencing. The DNA sequences and deduced amino acid sequences were compared with genes in the GenBank database ( or the β-lactamase classification system ( to confirm the subtypes of β-lactamase genes. "

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    • "E. coli NTCC 50192 yielding four plasmid bands of 148, 64, 36 and 7 kb was used as standard size marker. Location of ESBL genes was further analysed using Southern blot hybridization performed on plasmid DNAs of the ESBL-producing strains as previously described (Wu et al., 2011). Plasmid DNAs were transferred from agarose gel to a nylon membrane (Roche Diagnostics, Germany) and hybridized with digoxigenin-labelled gene fragments using PCR DIG detection system (DIG DNA labelling and detection kit; Roche Diagnostics ) according to the manufacturer's instructions. "
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    • "Also, Aeromonas hydrophilia isolated in Limpopo Province of South Africa was found to be positive for blaTEM gene [34]; however, our study is the first report on the presence of blaTEM gene in Aeromonas isolates from Eastern Cape Province of South Africa. In another study, three Aeromonas hydrophila strains isolated from patients blood in Taiwan were found to harbour blaTEM gene [35], and another report of blaTEM gene positive Aeromonas hydrophilia from an aged patient with necrotizing fasciitis [36] and fecal Aeromonas caviae from a patient with intestinal ischemia in France [35, 37], has been documented. The presence of β-lactamase gene in both clinical and environmental isolates of Aeromonas species is worrisome as it tends to limit treatment options in Aeromonas infections. "
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