Multidrug-Resistant Klebsiella pneumoniae ST307 in Traveler Returning from Puerto Rico to Dominican Republic

Research Progress on the Correlation Between Hypertension and Gut Microbiota

Among cardiovascular diseases, hypertension is the most important risk factor for morbidity and mortality worldwide, and its pathogenesis is complex, involving genetic, dietary and environmental factors. The characteristics of the gut microbiota can vary in response to increased blood pressure (BP) and influence the development and progression of hypertension. This paper describes five aspects of the relationship between hypertension and the gut microbiota, namely, the different types of gut microbiota, metabolites of the gut microbiota, sympathetic activation, gut-brain interactions, the effects of exercise and dietary patterns and the treatment of the gut microbiota through probiotics, faecal microbiota transplantation (FMT) and herbal remedies, providing new clues for the future prevention of hypertension. Diet, exercise and traditional Chinese medicine may contribute to long-term improvements in hypertension, although the effects of probiotics and FMT still need to be validated in large populations.

Comparison of Virulence between Two Main Clones (ST11 and ST307) of Klebsiella pneumoniae Isolates from South Korea

In this study, we investigate the characteristics of two main clones of carbapenemase-producing Klebsiella pneumoniae isolates from South Korea, ST11 and ST307, including carbapenem-susceptible isolates. Antibiotic susceptibility, serotype or wzi allelic type, the presence of virulence genes, and virulence with respect to serum resistance and macrophage internalization were determined for ST11 and ST307 isolates. ST11 isolates had a wide range of characteristics, including serotype and virulence, compared with those of homogeneous ST307 isolates. The wzi14 or K14 type had higher virulence than that of other serotypes among the ST11 isolates, and the homogeneous ST307 isolates showed similar virulence level as that of the wzi14-type ST11 isolates. Our data suggest that it is necessary to monitor not only the introduction and spread of a specific clone, but also its detailed serotype.

Molecular epidemiology and mechanisms of tigecycline resistance in carbapenem-resistant Klebsiella pneumoniae isolates

BACKGROUND

The emergence and transmission of tigecycline- and carbapenem-resistant Klebsiella pneumoniae (TCRKP) have become a major concern to public health globally. Here, we investigated the molecular epidemiology and mechanisms of tigecycline resistance in carbapenem-resistant K pneumoniae (CRKP) isolates.

METHODS

Forty-five non-duplicate CRKP isolates were collected from January 2017 to June 2019. We performed antimicrobial susceptibility tests, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). PCR and DNA sequencing were performed for the detection and mutation analysis of acrR, oqxR, ramR, rpsJ, tet(A), and tet(X) genes, which are related to tigecycline resistance. The expression levels of efflux pump genes acrB and oqxB and their regulator genes rarA, ramA, soxS, and marA were assessed by quantitative real-time PCR.

RESULTS

The resistance rate to tigecycline in CRKP isolates was 37.8% (17/45). K pneumoniae ST307 was a predominant clone type (70.6%, 12/17) among the TCRKP isolates. The expression levels of acrB (P < .001) and marA (P = .009) were significantly higher in the tigecycline-resistant group than in the tigecycline-intermediate and tigecycline-susceptible groups. Increased expression of acrB was associated with marA expression (r = 0.59, P = .013).

CONCLUSIONS

We found that the activated MarA-induced overexpression of AcrAB efflux pump plays an important role in the emergence of tigecycline resistance in CRKP isolates.

Emerging Antimicrobial-Resistant High-Risk Klebsiella pneumoniae Clones ST307 and ST147

There is an enormous global public health burden due to antimicrobial-resistant (AMR) Klebsiella pneumoniae high-risk clones. K. pneumoniae ST307 and ST147 are recent additions to the family of successful clones in the species. Both clones likely emerged in Europe during the early to mid-1990s and, in a relatively short time, became prominent global pathogens, spreading to all continents (with the exception of Antarctica). ST307 and ST147 consist of multiple clades/clusters and are associated with various carbapenemases (i.e., KPCs, NDMs, OXA-48-like, and VIMs). ST307 is endemic in Italy, Colombia, the United States (Texas), and South Africa, while ST147 is endemic in India, Italy, Greece, and certain North African countries. Both clones have been introduced into regions of nonendemicity, leading to worldwide nosocomial outbreaks. Genomic studies showed ST307 and ST147 contain identical gyrA and parC mutations and likely obtained plasmids with bla _CTX-M-15 during the early to mid-2000s, which aided in their global distribution. ST307 and ST147 then acquired plasmids with various carbapenemases during the late 2000s, establishing themselves as important AMR pathogens in certain regions. Both clones are likely underreported due to restricted detection methodologies. ST307 and ST147 have the ability to become major threats to public health due to their worldwide distribution, ability to cause serious infections, and association with AMR, including panresistance. The medical community at large, especially those concerned with antimicrobial resistance, should be aware of the looming threat posed by emerging AMR high-risk clones such as K. pneumoniae ST307 and ST147.

Update on the epidemiology of carbapenemases in Latin America and the Caribbean

INTRODUCTION

Carbapenemases are β-lactamases able to hydrolyze a wide range of β-lactam antibiotics, including carbapenems. Carbapenemase production in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp., with and without the co-expression of other β-lactamases is a serious public health threat. Carbapenemases belong to three main classes according to the Ambler classification: class A, class B, and class D.

AREAS COVERED

Carbapenemase-bearing pathogens are endemic in Latin America. In this review, we update the status of carbapenemases in Latin America and the Caribbean.

EXPERT OPINION

Understanding the current epidemiology of carbapenemases in Latin America and the Caribbean is of critical importance to improve infection control policies limiting the dissemination of multi-drug-resistant pathogens and in implementing appropriate antimicrobial therapy.

IMP-38-Producing High-Risk Sequence Type 307 Klebsiella pneumoniae Strains from a Neonatal Unit in China

An emerging multidrug-resistant Klebsiella pneumoniae high-risk clone of sequence type 307 (ST307) has been increasingly reported worldwide. Here, we described the genomic characteristics of an IMP-38-producing ST307 K. pneumoniae strain and investigated the prevalence of blaIMP-38 among carbapenem-resistant Klebsiella pneumoniae isolates from a tertiary care hospital in central China. A total of 14 IMP-38-producing ST307 K. pneumoniae strains were identified from 2013 to 2016, with 13 strains isolated from patients with neonatal sepsis in the neonatal ward. PacBio and Illumina whole-genome sequencing analysis performed on a representative IMP-38-producing K. pneumoniae strain, WCGKP294, showed that it contained a circular chromosome and two plasmids. Carbapenemase gene blaIMP-38 is colocated with blaCTX-M-3 in transposon Tn6382 on an IncHI5 plasmid (pWCGKP294-2). WCGKP294 harbors another IncFIB plasmid, pWCGKP294-1, carrying three copies of tandem-repeated IS26-blaSHV-2A-deoR-ygbJ-ygbK-fucA-IS26 composite transposon elements. Phylogenetic analysis placed WCGKP294 in the global ST307 cluster, distant from the U.S. (Texas) and South Africa clusters. Nevertheless, WCGKP294 does not contain the chromosomal fluoroquinolone resistance-associated mutations and IncFIIK/IncFIBK plasmid-associated blaCTX-M-15 gene that are frequently found in other global ST307 strains.IMPORTANCE We described the genome and resistome characterization of a carbapenem-resistant Klebsiella pneumoniae ST307 strain carrying blaIMP-38 in China. This report highlights that the high-risk ST307 clone continues to acquire different antimicrobial resistance genes, posing significant challenges to clinical practice, and should be closely monitored.