Elsevier

Infection, Genetics and Evolution

Volume 73, September 2019, Pages 184-189
Infection, Genetics and Evolution

Research paper
Considerable rate of putative virulent phylo-groups in fecal carriage of extended-spectrum β-lactamase producing Escherichia coli

https://doi.org/10.1016/j.meegid.2019.04.035Get rights and content

Highlights

  • Carriers of ESBL-producing E.coli are mostly asymptomatic which could affect in the rate of fecal carriages.

  • ESBL genes are mostly located on mobile genetic elements like conjugative plasmids, therefore they are easily transferred.

  • Analyses of phylogenetic groups, particularly virulent extra-intestinal groups are considerable in fecal carriages.

  • Tracking of clinical sequence types in ESBL-producing E.coli isolated from asymptomatic carriers is significant point.

Abstract

Extended-Spectrum Beta–lactamase producing Enterobacteriales (ESBL-PE) in fecal carriage have become a global health concern. Detection of putative virulent ESBL-producing E.coli (ESBL-EC) isolates among asymptomatic carriers is a threatening issue in public health. The aim of this study was to investigate the intestinal carriage of ESBL-EC, phylo-groups and clonal relatedness among putative virulent groups of ESBL-EC isolated from fecal carriages. A total of 120 rectal swabs; 50.8% (61/120) from inpatients of intensive care unit (ICU) and 49.2% (59/120) from outpatients were collected. The ESBL-EC screening was performed by using MacConkey agar supplemented with cefotaxime. PCR assays were applied for determination of phylo-groups, detection of ESBL and carbapenemase genes. Conjugation experiment, plasmid replicon typing and Multilocus Sequence Typing (MLST) were performed for putative virulent phylo-groups. Totally, of 120 studied individuals, 60.0% (72/120) were carrier for ESBL-EC. The rate of blaCTX-M-15, blaTEM, blaSHV was 90.2% (65/72), 50.0% (36/72) and 5.5% (4/72), respectively. The frequency of phylo-groups A, B1, B2, C, D, and F were 20.8% (15/72), 6.9% (5/72), 20.8% (15/72), 2.7% (2/72), 13.8 (10/72) and 12.5% (9/72), respectively. In conjugation experiments, of 6 tested isolates, 5 had conjugative plasmids. The most prevalent plasmid types belonged to IncF incompatibility groups. The MLST analysis showed that the main sequence types among ESBL-EC isolates were ST769 and ST472. The current study provides novel information about the presence of the ESBL-EC isolates, particularly putative virulent phylo-groups among fecal carriages in Iran. Our data revealed that there was almost high ST heterogeneity among putative ESBL-EC isolates. In order to implementation of effective infection control program, detection of fecal carriage in appropriate time typically at the beginning of admission to the hospital is recommended.

Introduction

Extended-Spectrum Beta-lactamase producing Enterobacteriales (ESBL-PE) notably E.coli have been recently detected in both nosocomial and community acquired infections (Popejoy et al., 2016). Along with clinically related ESBL producing isolates, the fecal carriage of ESBL-PE has been recently emerged as a global health concern. Since the majority of carriers are asymptomatic, therefore, it gives rises to expansion of ESBL-PE fecal carriages (Ebrahimi et al., 2016). Uncontrolled use of antibiotics and transmission of resistant bacterial isolates are two main reasons for increasing of fecal carriage rate (de Lastours et al., 2010). Intestinal colonization by ESBL-PE is considerable since ESBL genes are mostly located on conjugative plasmids. This could leads to transmission of resistance genes to other bacteria across species boundaries, horizontal transmission to other persons and infection in the host (Lübbert et al., 2015). Furthermore, they also usually carry other genes that are associated with aminoglycoside or fluoroquinolone resistance (Dolejska and Papagiannitsis, 2018). This situation is of the great concern, as transmission of these plasmids could be resulted in intestinal colonization with multi-drug resistant isolates. These plasmids belong to the diverse incompatibility groups, most, including Inc. A/C, L/M, F, I1, HI2, and N (Solgi et al., 2017a, Solgi et al., 2017b). Resistance genes are usually specific to a certain type of plasmids, for example the blaCTX-M-15 gene is carried on IncFII conjugative plasmids (Giedraitienė et al., 2017).

Phylo-grouping study, as a PCR-based typing method, puts E.coli into seven major groups including A, B1, B2, C, D, E and F. Determination of the phylo-group types in E.coli is important as it could possibly represent the potency of pathogenicity in E.coli isolates. Significantly, strains responsible for extra-intestinal infection were far more likely to be members of phylo-groups B2 or D than A or B1. (Clermont et al., 2013).

On the other hand, typing by multi locus sequence typing (MLST) has been proven to be useful technique in order to better understand and to determine the clonal relatedness among isolates. Moreover, analyses of phylogenetic groups, particularly virulent extra-intestinal groups (B2, D and F) (Clermont et al., 2000) are also considerable in fecal carriages (Cornejo-Juárez et al., 2016). Detection of clinically related sequence types of ESBL-EC isolates among asymptomatic carriers is a critical issue in public health since presence of this microorganisms particularly putative virulent phylogroups such as B2 and D in the intestine, could result to increase the risk of infection in fecal carriage.

To the best of our knowledge, a few studies have been carried out about ESBL-PE fecal carriages in Iran (Aghamohammad et al., 2018; Solgi et al., 2017). However, further investigation regarding ESBL-PE carriers is essential for implementation of successful prevention and control program for ESBL-PE. The aim of the present study was to investigate the intestinal carriage of ESBL-EC, determination of phylo-groups and clonal relatedness among putative virulent groups of ESBL-EC strains isolated from fecal carriages.

Section snippets

Ethical statement and bacterial isolates

The current cross-sectional study was conducted in a university general hospital in Tehran, Iran during January to October of 2016. Totally 120 rectal swabs (RS) were randomly collected from ICU patients and outpatients. All studied patients signed an informed consent form before sampling and declared their willingness to allow the application of their sample and anonymous data for research purposes (IR.PII.REC.1395.44). Rectal swabs were transferred in Tryptic Soy Broth containing a 30-μg

Detection of ESBL-EC in rectal swabs

A total of 120 non-duplicated rectal swabs; 50.8% (61/120) from inpatients of intensive care unit (ICU) and 49.2% (59/120) from outpatients were collected. Based on our results 60.0% (72/120) of studied individuals, including 55.5% (40/72) of outpatients and 45.4% (32/72) of inpatients were carriers of ESBL-EC.

Antimicrobial susceptibility pattern

Disk diffusion method revealed the resistance rates of ESBL-EC isolates against ceftazidime and cefepime were 90.2% (65/72) and 93.0% (67/72), respectively. The rates of resistance to

Discussion

Clinical infections caused by ESBL-EC increase worldwide (Pulcini et al., 2018). Several studies determined about phylo-groups among E.coli mostly isolated from clinical isolates and fecal carriages (Jørgensen et al., 2017; Johnson et al., 2014).

Intestinal colonization by putative virulent phylo-groups of ESBL-EC such as B2, D and F in fecal carriage is important. The majority of carriers are asymptomatic, however, certain condition such as intestine barrier break, could leads to various

Acknowledgment

The authors would like to thank the personnel in the bacteriology department of Pasture Institute of Iran and Loghman Hospital for their help.

Funding

This work was funded by research grant from Pasteur Institute of Iran (project no: B-9216 and 1404).

Ethical statement

This project was done based on ethical guidelines as previously approved by the Pasteur institute of Iran (project no: 180 IR.PII.REC.1397.56).

Conflict of interest

The authors have no conflicts of interest to declare.

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