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Nationwide high prevalence of CTX-M and an increase of CTX-M-55 in Escherichia coli isolated from patients with community-onset infections in Chinese county hospitals.

Zhang J, Zheng B, Zhao L, Wei Z, Ji J, Li L, Xiao Y - BMC Infect. Dis. (2014)

Bottom Line: ESBL activity was confirmed by double-disc diffusion.This is the first time the incidence of CTX-M-55 has exceeded that of CTX-M-15 in China.No predominant ST was detected, suggesting that ESBL-producing E. coli strains originate in different clones.

View Article: PubMed Central - PubMed

Affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Disease, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China. z-j2011@hotmail.com.

ABSTRACT

Background: In order to investigate the epidemiology, molecular characteristics, and distribution of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Escherichia coli from community-onset infections in Chinese county hospitals.

Methods: E. coli isolates were collected from patients with community-onset infections in 30 county hospitals. ESBL activity was confirmed by double-disc diffusion. Genetic confirmation and molecular typing of ESBL- and AmpC-producing isolates was determined by PCR and DNA sequencing. ESBL-positive isolates were further characterised by multi-locus sequence typing.

Results: Of 550 E. coli isolates, 256 (46.5%) carried ESBL genes and all were of the CTX-M type. The prevalence of ESBL-producing strains varied from 30.2% to 57.0% across different regions of China. Overall, 12 bla CTX-M subtypes were detected; the most abundant were bla CTX-M-14 (163/256 isolates, 64.5%), bla CTX-M-55 (47/256, 18.4%), and bla CTX-M-15 (31/256, 12.1%). CMY-2-like AmpC β-lactamases were detected in 11 strains, three of which co-existed with bla CTX-M. A total of 64 sequence types (STs) were detected in 256 ESBL-producing strains, including nine that were new. ST131 was the most abundant type (27 isolates, 12.7%), followed by ST69 (14 isolates, 6.6%), ST405 (14 isolates, 6.6%), and ST38 (12 isolates, 5.6%).

Conclusions: This study revealed that the widespread prevalence of ESBLs among outpatient infections has reached a high level in county hospitals. The CTX-M genotype was most dominant, comprising a variety of subtypes. This is the first time the incidence of CTX-M-55 has exceeded that of CTX-M-15 in China. No predominant ST was detected, suggesting that ESBL-producing E. coli strains originate in different clones.

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Related in: MedlinePlus

Phylogenetic tree of STs detected in this study using Phylodendron. This tool uses the PHYLIP suite of programs to generate trees from allelic profile data. Phylogenetic tree generated in this study indicated there was no concentrated distribution of STs in ESBL-producing genotypes.
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Fig2: Phylogenetic tree of STs detected in this study using Phylodendron. This tool uses the PHYLIP suite of programs to generate trees from allelic profile data. Phylogenetic tree generated in this study indicated there was no concentrated distribution of STs in ESBL-producing genotypes.

Mentions: MLST revealed 64 different STs, and nine new STs that are not registered in the E. coli MLST database. ST131 was the most abundant type (27 isolates, 12.7%), followed by ST69 (14 isolates, 6.6%), ST405 (14 isolates, 6.6%), and ST38 (12 isolates, 5.6%). The sources for the ST131 isolates were distributed across 14 hospitals from seven regions. Among the ST131 isolates, 18 were positive for CTX-M-14, five were positive for CTX-M-55, three were positive for CTX-M-15, and one was positive for both CTX-M-14 and CTX-M-3. Three Northwest hospitals provided 66.7% of the ST38 strains (n = 12). These three hospitals are located far from each other in Xinjiang province. One hospital accounted for 50% (4/8 isolates) of ESBL-producing strains. ST38 was the dominant type in these three hospitals, but was not found in the one hospital in Xinjiang. A phylogenetic tree of STs detected in this study using a Phylodendron is shown in Figure 2.Figure 2


Nationwide high prevalence of CTX-M and an increase of CTX-M-55 in Escherichia coli isolated from patients with community-onset infections in Chinese county hospitals.

Zhang J, Zheng B, Zhao L, Wei Z, Ji J, Li L, Xiao Y - BMC Infect. Dis. (2014)

Phylogenetic tree of STs detected in this study using Phylodendron. This tool uses the PHYLIP suite of programs to generate trees from allelic profile data. Phylogenetic tree generated in this study indicated there was no concentrated distribution of STs in ESBL-producing genotypes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4265337&req=5

Fig2: Phylogenetic tree of STs detected in this study using Phylodendron. This tool uses the PHYLIP suite of programs to generate trees from allelic profile data. Phylogenetic tree generated in this study indicated there was no concentrated distribution of STs in ESBL-producing genotypes.
Mentions: MLST revealed 64 different STs, and nine new STs that are not registered in the E. coli MLST database. ST131 was the most abundant type (27 isolates, 12.7%), followed by ST69 (14 isolates, 6.6%), ST405 (14 isolates, 6.6%), and ST38 (12 isolates, 5.6%). The sources for the ST131 isolates were distributed across 14 hospitals from seven regions. Among the ST131 isolates, 18 were positive for CTX-M-14, five were positive for CTX-M-55, three were positive for CTX-M-15, and one was positive for both CTX-M-14 and CTX-M-3. Three Northwest hospitals provided 66.7% of the ST38 strains (n = 12). These three hospitals are located far from each other in Xinjiang province. One hospital accounted for 50% (4/8 isolates) of ESBL-producing strains. ST38 was the dominant type in these three hospitals, but was not found in the one hospital in Xinjiang. A phylogenetic tree of STs detected in this study using a Phylodendron is shown in Figure 2.Figure 2

Bottom Line: ESBL activity was confirmed by double-disc diffusion.This is the first time the incidence of CTX-M-55 has exceeded that of CTX-M-15 in China.No predominant ST was detected, suggesting that ESBL-producing E. coli strains originate in different clones.

View Article: PubMed Central - PubMed

Affiliation: Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Disease, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China. z-j2011@hotmail.com.

ABSTRACT

Background: In order to investigate the epidemiology, molecular characteristics, and distribution of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Escherichia coli from community-onset infections in Chinese county hospitals.

Methods: E. coli isolates were collected from patients with community-onset infections in 30 county hospitals. ESBL activity was confirmed by double-disc diffusion. Genetic confirmation and molecular typing of ESBL- and AmpC-producing isolates was determined by PCR and DNA sequencing. ESBL-positive isolates were further characterised by multi-locus sequence typing.

Results: Of 550 E. coli isolates, 256 (46.5%) carried ESBL genes and all were of the CTX-M type. The prevalence of ESBL-producing strains varied from 30.2% to 57.0% across different regions of China. Overall, 12 bla CTX-M subtypes were detected; the most abundant were bla CTX-M-14 (163/256 isolates, 64.5%), bla CTX-M-55 (47/256, 18.4%), and bla CTX-M-15 (31/256, 12.1%). CMY-2-like AmpC β-lactamases were detected in 11 strains, three of which co-existed with bla CTX-M. A total of 64 sequence types (STs) were detected in 256 ESBL-producing strains, including nine that were new. ST131 was the most abundant type (27 isolates, 12.7%), followed by ST69 (14 isolates, 6.6%), ST405 (14 isolates, 6.6%), and ST38 (12 isolates, 5.6%).

Conclusions: This study revealed that the widespread prevalence of ESBLs among outpatient infections has reached a high level in county hospitals. The CTX-M genotype was most dominant, comprising a variety of subtypes. This is the first time the incidence of CTX-M-55 has exceeded that of CTX-M-15 in China. No predominant ST was detected, suggesting that ESBL-producing E. coli strains originate in different clones.

Show MeSH
Related in: MedlinePlus