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, Oct 06, 2015
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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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    ABSTRACT: Aeromonas species are becoming renowned as emerging pathogens by increasingly giving rise to a wide spectrum of food and waterborne infections in humans. Another worrisome feature of aeromonads is the growing frequency of antibiotic resistance as a consequence of their prominent diversity in terms of resistance determinants. This study aimed at determining the antimicrobial resistance pattern, prevalence and characterization of acquired β-lactamases, including extended-spectrum-β-lactamases (ESBLs) and AmpC cephalosporinases, as well as the presence of class 1 and 2 integrons, in Aeromonas isolates from wild-growing Mediterranean mussel (Mytilus galloprovincialis) of the eastern coast of Adriatic Sea, Croatia. Isolates were tested for susceptibility to 16 antibiotics and β-lactam/β-lactamase inhibitor combinations. Cephalosporin-resistant isolates were further screened by PCR for genes encoding AmpC (blaFOX, blaCMY, blaMOX, blaLAT, blaBIL, blaDHA, blaACC, blaMIR, blaACT), ESBLs (blaTEM, blaSHV, blaCTX-M, blaPER, blaVEB, blaGES/IBC, blaOXA) and integrases (intI1, intI2, intI3). Location of bla genes was characterized by plasmid DNA fingerprinting and Southern blot hybridization. Plasmids carrying ESBL genes were investigated for transferability by conjugation and PCR-based replicon typed. Out of 147 Aeromonas isolates recovered, 30 (20%) demonstrated multiple resistance profile, with co-resistance most frequently detected against penicillins, piperacillin/sulbactam and tetracycline. ESBL-encoding genes were detected in 21 (13 Aeromonas caviae and 8 Aeromonas hydrophila) isolates, with blaCTX-M-15 gene identified in 19 and blaSHV-12 in 12 isolates. Among them, 10 isolates simultaneously harboured blaCTX-M-15 and blaSHV-12, while 3 isolates additionally carried an AmpC β-lactamase blaFOX-2 gene. blaPER-1 gene was identified in a single isolate also harbouring the blaCTX-M-15 gene. While blaSHV-12 was chromosomally encoded, blaCTX-M-15 was located on conjugative IncFIB-type plasmids of ~40kb in A. caviae isolates. IntI1 and intI2 genes were detected in 57.1% and 33.3% of ESBL-producing isolates. To the best our knowledge, this is the first report of environmental A. caviae isolates producing CTX-M-15, and isolation of SHV-12-producing A. hydrophila and A. caviae strains worldwide. This is also believed to be the first report of the FOX-2, CTX-M-15 and SHV-12 simultaneous production in aeromonads, highlighting both the potential risk for human health, and a role of these foodborne pathogens as reservoirs of resistance determinants in coastal marine environment.
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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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    ABSTRACT: This study assessed the prevalence of antibiotic-resistant Aeromonas species isolated from Alice and Fort Beaufort wastewater treatment plant in the Eastern Cape Province of South Africa. Antibiotic susceptibility was determined using the disc diffusion method, and polymerase chain reaction (PCR) assay was employed for the detection of antibiotics resistance genes. Variable susceptibilities were observed against ciprofloxacin, chloramphenicol, nalidixic acid, gentamicin, minocycline, among others. Aeromonas isolates from both locations were 100% resistant to penicillin, oxacillin, ampicillin, and vancomycin. Higher phenotypic resistance was observed in isolates from Fort Beaufort compared to isolates from Alice. Class A pse1 β-lactamase was detected in 20.8% of the isolates with a lower detection rate of 8.3% for blaTEM gene. Class 1 integron was present in 20.8% of Aeromonas isolates while class 2 integron and TetC gene were not detected in any isolate. The antibiotic resistance phenotypes observed in the isolates and the presence of β-lactamases genes detected in some isolates are of clinical and public health concern as this has consequences for antimicrobial chemotherapy of infections associated with Aeromonas species. This study further supports wastewater as potential reservoirs of antibiotic resistance determinants in the environment.
    The Scientific World Journal 08/2012; 2012:764563. DOI:10.1100/2012/764563 · 1.73 Impact Factor
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