Abstract | AIM: To estimate the prevalence and characterise plasmid-mediated AmpC beta-lactamase (PMACBL)- producing Escherichia coli in the Auckland community. METHOD: All cefoxitin non-susceptible (NS) E. coli identified at the two Auckland community laboratories between 1 January and 31 August 2011 were referred to ESR for boronic acid double-disc synergy testing, to detect the production of AmpC beta-lactamase, and polymerase chain reaction (PCR) to identify the presence of PMACBL genes. PMACBL-producing isolates were typed using pulsed-field gel electrophoresis (PFGE), and PCR was used to determine their phylogenetic group and to identify multilocus sequence type (ST)131. Antimicrobial susceptibility testing and detection of extended-spectrum beta-lactamases (ESBLs) were performed according to the Clinical and Laboratory Standards Institute recommendations. RESULTS: 101 (51%) and 74 (37%) of 200 non-duplicate cefoxitin-NS E. coli were PMACBL producers or assumed hyper-producers of chromosomal AmpC beta-lactamase, respectively. The prevalence of PMACBL-producing E. coli was 0.4%. PMACBL-producing E. coli were significantly less susceptible to norfloxacin, trimethoprim and nitrofurantoin than E. coli that produced neither a PMACBL nor an ESBL. Very few (4%) PMACBL-producing E. coli co-produced an ESBL. Most (88%) of the PMACBL-producing isolates had a CMY-2-like PMACBL. The PMACBL-producing E. coli isolates were diverse based on their PFGE profiles, 44% belonged to phylogenetic group D, and only four were ST131. 100 of the 101 PMACBL-producing E. coli were cultured from urine, and were causing urinary tract infection (UTI) in the majority of patients. The median patient age was 56 years and most (94%) of the patients were women. A greater proportion of patients with community-acquired UTI caused by PMACBL-producing E. coli received a beta-lactam antimicrobial than patients with community-acquired UTI caused by other non-AmpC, non-ESBL-producing E. coli. Thirty-six (43%) patients with community-acquired UTI due to PMACBL-producing E. coli were neither hospitalised nor had any antimicrobial treatment in the previous 6 months. CONCLUSION: The prevalence of PMACBL-producing E. coli was relatively low in the Auckland community, but has increased in recent years. Typing revealed that the majority of the PMACBL-producing E. coli in the Auckland region were genetically unrelated meaning that a point source or direct person to person transmission are not drivers of local community spread currently. The isolates were more resistant to non- beta-lactam antimicrobials than other non-AmpC, non-ESBL-producing E. coli, leaving few treatment options. The majority of the PMACBL-producing E. coli isolates seemed to be acquired in the community and were most frequently isolated from women with UTI. A large proportion of patients with community-acquired UTI had not been hospitalised nor had any antimicrobial treatment in the previous 6 months.
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Authors | Dragana Drinkovic, Arthur J Morris, Kristin Dyet, Sarah Bakker, Helen Heffernan |
Journal | The New Zealand medical journal
(N Z Med J)
Vol. 128
Issue 1410
Pg. 50-9
(Mar 13 2015)
ISSN: 1175-8716 [Electronic] New Zealand |
PMID | 25829039
(Publication Type: Journal Article)
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Chemical References |
- Anti-Bacterial Agents
- Bacterial Proteins
- DNA, Bacterial
- AmpC beta-lactamases
- beta-Lactamases
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Topics |
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Anti-Bacterial Agents
(therapeutic use)
- Bacterial Proteins
(genetics, metabolism)
- Child
- Child, Preschool
- Community-Acquired Infections
(drug therapy, epidemiology, microbiology)
- DNA, Bacterial
(analysis)
- Drug Resistance, Bacterial
(genetics)
- Escherichia coli
(genetics, metabolism)
- Escherichia coli Infections
(drug therapy, epidemiology, microbiology)
- Female
- Humans
- Infant
- Male
- Microbial Sensitivity Tests
- Middle Aged
- Molecular Epidemiology
- New Zealand
(epidemiology)
- Plasmids
(genetics)
- Urinary Tract Infections
(drug therapy, epidemiology, microbiology)
- Young Adult
- beta-Lactamases
(genetics, metabolism)
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