Elsevier

Microbial Pathogenesis

Volume 159, October 2021, 105124
Microbial Pathogenesis

Significant downtrend of antimicrobial resistance rate and rare β-lactamase genes and plasmid replicons carriage in clinical Pseudomonas aeruginosa in Southern China

https://doi.org/10.1016/j.micpath.2021.105124Get rights and content

Highlights

  • The resistant rate of the 13 tested antibiotic agents showed a downtrend.

  • The most predominant specimen source of P. aeruginosa was sputum.

  • P. aeruginosa isolates rarely carried β-lactam resistance genes.

  • The carriage rate of plasmid replicons in P. aeruginosa isolates was low.

Abstract

Objectives

Pseudomonas aeruginosa is a medically important pathogen showing intrinsic low permeability to various antimicrobial agents and its potential to acquire multiple resistance mechanism. A longitudinal surveillance aimed to investigate the antimicrobial resistance and its determinants of Pseudomonas aeruginosa in Southern China. A total of 2163 P. aeruginosa isolates were obtained from patients in Southern China during 2004–2016.

Methods

The antimicrobial susceptibility of the isolates was performed by disk diffusion and Vitek 2 automated system and interpreted according to the Clinical and Laboratory Standard Institute (CLSI) 2015.

Results

A significant downtrend of resistant rate (>10.0%) was observed for tested antibiotic agents including ciprofloxacin (>30.0%), gentamicin (29.0%), tobramycin (24.2%) and ceftazidime (24.0%) except for aztreonam and amikacin. A total of 269 randomly selected isolates were further studied on the carriage of β-lactam resistance genes by using 7 groups of multiplex PCRs targeting on 20 genes. β-lactam resistance genes were rarely detected with a rate lower than 8%. Among all β-lactam resistance genes, blaSHV acquired the highest identification rate (18/269, 6.7%), followed by blaOXA-1-like (6/269, 2.2%) and blaPER (6/269, 2.2%). In addition, 8 different plasmid replicons were amplified using 8 groups of multiplex PCRs including 18 sets of primers. Only five plasmid replicons were identified in 5 different P. aeruginosa isolates. Insignificant clonal relatedness among the positive strains identified by regular PCR were further verified by randomly amplified polymorphic DNA (RAPD)-PCR.

Conclusion

This study has provided comprehensive knowledge on current antimicrobial resistance, β-lactam resistance genes and plasmid replicons carriage in a large scale of clinical P. aeruginosa isolates.

Introduction

Pseudomonas aeruginosa is one of the most important opportunistic human pathogens causing both acute and chronic infections especially for nosocomial infections [1]. Recently, P. aeruginosa is noted for its increasing resistance rates to many kinds of antibiotics worldwide and its ability to acquire genes encoding resistance determinants [2]. As therapeutic treatment was concerned, selection of appropriate antibiotics is complicated because of the potential to acquire multiple resistance machanisms of P. aeruginosa [3]. As an important type of antibiotics, β-lactams are widely applied in P. aeruginosa infections. Considering the accumulation of multiple mechanisms of resistance will leads to multi-drug resistance, we take into account the key genes of multiple drug resistance mechanisms in this research. The major mechanism of resistance is the production of β-lactamases, followed by other important mechanisms including diminished expression of outer membrane proteins, mutations in topoisomerases, and up-regulation of efflux pumps [2]. Plasmid-mediated AmpC β-lactamases is characteristically chromosomally encoded in P. aeruginosa. Considering its contribution to the resistance mechanism to ticarcillin, piperacillin, and third-generation cephalosporins, DHA-type and CMY-type β-lactams were detected in this study [2,4]. Class A-type-β-lactamase is now emerging as a dominant extended-spectrum-β-lactams (ESBLs) type. Amongst, PER-type is common in P. aeruginosa, followed by other less common class A-type-β-lactamase (VEB-type, GES-type TEM-type, SHV-type, and CTX-M-type β-lactamase) [4,5]. Aminoglycoside-modifying enzymes (AMEs, especially ACC-type) were found to be one of the features of multidrug-resistant phenotype [6]. Other β-lactamases conferring resistance to carbapenems were emerged recently, such as KPC carbapenemases, some class D-type-β-lactamases (OXA-1-type, OXA-48-type, etc.) [7]. These sequences increase the spectrum of activity of the β-lactamases against antibiotics including ceftazidime or aztreonam. The major types of metallo-β-lactamases (MBLs, such as IMP-type and VIM-type), which are responsible for the resistance of imipenem and meropenem plus the antipseudomonal cephalosporins, including cefepime, and antipseudomonal penicillins, were also included in this study [8].

The dissemination of β-lactams resistance in Gram-negative bacteria including P. aeruginosa has been largely attributed to the horizontal transfer of β-lactamase genes by plasmids [[9], [10], [11]]. Plasmids contain genes essential for initiation and control of replication and accessory genes, and are capable of increasing bacterial gene diversity (acquiring and losing genes), horizontally transferring among bacteria by conjugation or mobilization [[12], [13], [14]]. The carriage of replicons, which contribute to the replication of plasmid, represents the acquisition of plasmids by strains. Since replication is a constant and conserved part of plasmid, replicon typing is a sensitive and specific method for identifying phylogenetically related plasmids and may provide clues to the evolution of resistance plasmids. Moreover, as surveillance on antimicrobial resistance and its determinants, as well as plasmids is of great significance for clinicians to choose therapy, study on clinical P. aeruginosa isolates may facilitate further understanding of the horizontal transfer of antimicrobial drug resistance [15,16].

In this study, we collected and analysed the antimicrobial resistance data of 2163 P. aeruginosa isolates collected in a 13-year period, with their β-lactam resistance genes and plasmid replicons carrying rates further identified.

Section snippets

Hospital setting, bacterial isolates and clinical data

A total of 2163 P. aeruginosa were isolated from the First Affiliated Hospital of Guangzhou Medical University (FAHGMU), a tertiary teaching hospital with the leading clinical laboratory on microbiology in Southern China. Containing 1500 beds, the large proportion of patients in FAHGMU are from cities in Guangdong provinces and adjacent provinces and small number of patients even from Central, East and West China. As a consequence, the surveillance investigation on P. aeruginosa in this study

Antimicrobial resistance of P. aeruginosa

According to the susceptibility results, the highest resistance rate was obtained for β-lactam (43.5%), followed by monobactams (mean 33.4%) and carbapenems (mean 33.2%), fluoroquinolones (mean 29.2%), penicillins (mean 24.2%), cephems (mean 17.9%) and aminoglycosides (mean 14.6%). Remarkably, decrease in resistance rate (>10%) during 2004–2016 was observed for tested antibiotics except for ATM and AMK (Table 1). In detail, dramatical decrease from period 1 to period 4 in CIP (>30.0%, from

Conclusion

As concluded, this study has provided comprehensive knowledge on current antimicrobial resistance, β-lactam resistance genes and plasmid replicons carriage in a large scale of clinical P. aeruginosa isolates collected during 2004–2016. Significant downtrend of resistance rate was observed for the majority of tested antibiotics, and rare identification rate was found for both major β-lactamase genes and plasmid replicons. The spreading dissemination of β-lactamase genes carrying strains and

Author statement

Zhenbo Xu: Conceptualization, Methodology, Funding acquisition. Xin Lin: Formal analysis, Writing-Original draft preparation, Writing-Review & Editing. Thanapop Soteyome: Investigation. Yanrui Ye: Visualization, Resources. Dingqiang Chen: Data curation. Ling Yang: Resources. Junyan Liu: Supervision, Writing-Review & Editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This work was supported by the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030005), Guangdong International S&T Cooperation Programme (2021A0505030007), State Key Laboratory of Applied Microbiology Southern China (Grant No. SKLAM005-2019), National Key Research and Development Program of China (No. 2017YFC1601202), Collaborative grant with AEIC (KEO-2019-0624-001-1), the 111 Project (B17018).

References (45)

  • D.S. Burgess et al.

    Activity of piperacillin/tazobactam in combination with amikacin, ciprofloxacin and trovafloxacin against Pseudomonas aeruginosa by time-kill

    Diagn. Microbiol. Infect. Dis.

    (2000)
  • G. Yu et al.

    First report of novel genetic array aacA4-bla (IMP-25)-oxa30-catB3 and identification of novel metallo-beta-lactamase gene bla (IMP25): a retrospective study of antibiotic resistance surveillance on Psuedomonas aeruginosa in Guangzhou of South China, 2003-2007

    Microb. Pathog.

    (2016)
  • C. Adams et al.

    Epidemiology and clinical impact of Pseudomonas aeruginosa infection in cystic fibrosis using AP-PCR fingerprinting

    J. Infect.

    (1998)
  • R.A. Bonomo et al.

    Mechanisms of multidrug resistance in acinetobacter species and Pseudomonas aeruginosa

    Clin. Infect. Dis.

    (2006)
  • P.D. Lister et al.

    Antibacterial-resistant Pseudomonas aeruginosa: clinical impact and complex regulation of chromosomally encoded resistance mechanisms

    Clin. Microbiol. Rev.

    (2009)
  • C. Dallenne et al.

    Development of a set of multiplex PCR assays for the detection of genes encoding important beta-lactamases in Enterobacteriaceae

    J. Antimicrob. Chemother.

    (2010)
  • D.M. Livermore

    Multiple mechanisms of antimicrobial resistance in Pseudomonas aeruginosa: our worst nightmare?

    Clin. Infect. Dis.

    (2002)
  • G.H. Miller et al.

    The most frequent aminoglycoside resistance mechanisms-changes with time and geographic area: a reflection of aminoglycoside usage patterns? Aminoglycoside Resistance Study Groups

    Clin. Infect. Dis.

    (1997)
  • D. Yahav et al.

    New β-Lactam-β-Lactamase inhibitor combinations

    Clin. Microbiol. Rev.

    (2020)
  • C.T. Bergstrom et al.

    Natural selection, infectious transfer and the existence conditions for bacterial plasmids

    Genetics

    (2000)
  • S. Bergström et al.

    β-Lactam resistance in clinical isolates of Escherichia coli caused by elevated production of the ampC-mediated chromosomal β-lactamase

    Antimicrob. Agents Chemother.

    (1979)
  • K. Shannon et al.

    Hyperproduction of TEM-1 β-lactamase in clinical isolates of Escherichia coli serotype O15

    FEMS Microbiol. Lett.

    (1990)
  • Cited by (0)

    View full text