Global emergence of Carbapenem-resistant Hypervirulent Klebsiella pneumoniae driven by an IncFII KPC-2 plasmid.

Background: Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) has been increasingly reported worldwide, posing a severe challenge to public health; however, the mechanisms driving its emergence and global dissemination remain unclear.

Methods: We analysed CR-hvKp strains derived from canonical hvKp backgrounds, and acquired a carbapenemase-encoding gene. These strains were identified from 485 CRKp isolates in the CRACKLE-2 China cohort, 259 CRKp isolates from a multi-centre study, and 67,631 K.

The pivotal role of IncFIB(Mar) plasmid in the emergence and spread of hypervirulent carbapenem-resistant .

The hypervirulent carbapenem-resistant (hv-CRKP) poses a substantial challenge to the global health care. However, the mechanism behind its evolution and transmission remain elusive. Here, four virulence plasmid types were identified from 310 hv-CRKP isolates collected nationwide during 2017-2018, based on their aerobactin ( locus) lineage and IncFIB replicons.

The dilemma of antibiotic susceptibility and clinical decision-making in a multi-drug-resistant bloodstream infection.

How to choose the appropriate antibiotics and dosage has always been a difficult issue during the treatment of multi-drug-resistant bacterial infections. Our study aims to resolve this difficulty by introducing our multi-disciplinary treatment (MDT) clinical decision-making scheme based on rigorous interpretation of antibiotic susceptibility tests and precise therapeutic drug monitoring (TDM)-guided dosage adjustment. The treatment course of an elderly patient who developed a multi-drug-resistant (MDRPA) bloodstream infection from a brain abscess was presented.

Guidelines for the diagnosis, treatment, prevention and control of infections caused by carbapenem-resistant gram-negative bacilli.

The dissemination of carbapenem-resistant Gram-negative bacilli (CRGNB) is a global public health issue. CRGNB isolates are usually extensively drug-resistant or pandrug-resistant, resulting in limited antimicrobial treatment options and high mortality. A multidisciplinary guideline development group covering clinical infectious diseases, clinical microbiology, clinical pharmacology, infection control, and guideline methodology experts jointly developed the present clinical practice guidelines based on best available scientific evidence to address the clinical issues regarding laboratory testing, antimicrobial therapy, and prevention of CRGNB infections.

High-level ertapenem resistance in Klebsiella pneumoniae is due to RamA downregulation of ompK35 through micF.

An ertapenem-resistant Klebsiella pneumoniae clinical isolate (KP20) without carbapenemase and negative for the efflux pump inhibition test was resistant to ertapenem at a high level [minimum inhibitory concentration (MIC) = 64 mg/L] but susceptible to meropenem and imipenem. Second-generation sequencing was performed and a termination mutation was found in ramR. Complementation of ramR in KP20 reduced the ertapenem MIC by 128 times (from 64 mg/L to 0.

Antibiotic Exposure during the Preceding Six Months Is Related to Intestinal ESBL-Producing Enterobacteriaceae Carriage in the Elderly.

Intestinal carriage of extended-spectrum β-lactamase-producing (ESBL-PE carriage) poses a health risk to the elderly. It was aimed to study the prevalence and the risk factors of intestinal ESBL-PE carriage in the elderly. An observational study of a 921-elderly cohort was examined at health checkup for intestinal ESBL-PE carriage at a tertiary medical center in Shanghai.

RamA upregulates multidrug resistance efflux pumps AcrAB and OqxAB in Klebsiella pneumoniae.

Overexpression of the acrAB genes regulated by RamA and overexpression of oqxAB regulated by RarA have been reported to mediate multidrug resistance in Gram-negative bacilli. In this study, regulation of acrAB and oqxAB simultaneously by the global regulator RamA was investigated in a multidrug-resistant Klebsiella pneumoniae clinical isolate (KP22) resistant to tigecycline and other antimicrobials. KP22 overexpressed ramA due to a ramR mutation, along with an unexpected overexpression of oqxB.

The type I-E CRISPR-Cas system influences the acquisition of -IncF plasmid in .

carbapenemase (KPC)-producing (KPC-KP) have disseminated worldwide and emerged as major threats to public health. Of epidemiological significance, the international pandemic of KPC-KP is primarily associated with CG258 isolates and -IncF plasmids. CRISPR-Cas system is an adaptive immune system that can hinder gene expansion driven by horizontal gene transfer.

In vitro activities of acetylmidecamycin and other antimicrobials against human macrolide-resistant Mycoplasma pneumoniae isolates.

Objectives: To assess the in vitro activities of acetylmidecamycin, a 16-membered macrolide, and 11 other antimicrobial agents against human mycoplasmas.

Methods: A total of 187 clinical isolates, Mycoplasma pneumoniae (n = 110), Mycoplasma hominis (n = 26) and Ureaplasma species (n = 51), were included in this study. The MICs of 12 antimicrobial agents, including acetylmidecamycin, thiamphenicol, chloramphenicol and some other macrolides, fluoroquinolones and tetracyclines, for these clinical isolates were determined by the broth microdilution method.

Mycoplasma pneumoniae from the Respiratory Tract and Beyond.

is an important cause of respiratory tract infections in children as well as adults that can range in severity from mild to life-threatening. Over the past several years there has been much new information published concerning infections caused by this organism. New molecular-based tests for detection are now commercially available in the United States, and advances in molecular typing systems have enhanced understanding of the epidemiology of infections.

Pharmacodynamic Target Assessment of Eravacycline against Escherichia coli in a Murine Thigh Infection Model.

Eravacycline is a novel fluorocycline antibiotic with potent activity against a broad range of pathogens, including strains with tetracycline and other drug resistance phenotypes. The goal of the studies was to determine which pharmacokinetic/pharmacodynamic (PK/PD) parameter and magnitude best correlated with efficacy in the murine thigh infection model. Six isolates were utilized for the studies.

Development of an Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Amoxicillin in Broth Medium and its Application to an In Vitro Pharmacokinetic and Pharmacodynamic Model.

A simple, rapid and highly sensitive liquid chromatographic-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for the quantification of amoxicillin in broth-a liquid bacterial culture medium. After appropriate dilution with ultrapure water, broth samples containing amoxicillin and an internal standard (IS) were extracted by acetonitrile and dichloromethane. The extract was injected into the system.

Functions of a GyrBA fusion protein and its interaction with QnrB and quinolones.

In order to study the interactions between Escherichia coli DNA gyrase and the gyrase interacting protein QnrB in vivo, we constructed a gyrB-gyrA fusion and validated its ability to correct the temperature-sensitive growth of gyrA and gyrB mutants. Like wild-type gyrA, the gyrB-gyrA fusion complemented a quinolone-resistant gyrA mutant to increase susceptibility. It functioned as an active type II topoisomerase, catalyzed negative supercoiling of DNA, was inhibited by quinolone, and was protected by QnrB.

Interactions between QnrB, QnrB mutants, and DNA gyrase.

Plasmid-encoded protein QnrB1 protects DNA gyrase from ciprofloxacin inhibition. Using a bacterial two-hybrid system, we evaluated the physical interactions between wild-type and mutant QnrB1, the GyrA and GyrB gyrase subunits, and a GyrBA fusion protein. The interaction of QnrB1 with GyrB and GyrBA was approximately 10-fold higher than that with GyrA, suggesting that domains of GyrB are important for stabilizing QnrB1 interaction with the holoenzyme.

Prevalence of the fosfomycin-resistance determinant, fosB3, in Enterococcus faecium clinical isolates from China.

In order to investigate the prevalence of fosfomycin-resistance (fos) determinants in Enterococcus faecium, clinical strains were collected from hospitals throughout China between January 2008 and December 2009. Antimicrobial susceptibility testing was performed, after which the fos genes in all isolates and van genes in vancomycin-resistant isolates were characterized by PCR and sequencing. Conjugation experiments were carried out with fosB-positive E.

LC-MS/MS determination of colistin in Mueller-Hinton broth for in vitro pharmacodynamic studies.

A rapid and simple method was developed and validated for the determination of colistin A and B in Mueller-Hinton broth using LC-tandem MS. Both analyte and internal standard (IS) (polymyxin B1) were determined using ESI. The MS data were obtained via the selected reaction monitoring in positive-ion mode.

Development and validation of a new ultra-performance liquid chromatographic method for vancomycin assay in serum and its application to therapeutic drug monitoring.

Objective: The aim of this study was to develop and validate an ultra-performance liquid chromatographic (UPLC) method with photodiode array detector for the measurement of vancomycin in human serum samples for therapeutic drug monitoring or other applications.

Methods: The method included the extraction of vancomycin in serum by deproteinization with acetonitrile. The analyses were carried out using an ACQUITY UPLC BEH C(18) column (2.