MRK-A / Merck (MSD) - LARVOL DELTA

Difference in biofilm formation between carbapenem-resistant and carbapenem-sensitive Klebsiella pneumoniae based on analysis of mrkH distribution. (PubMed, Microb Pathog) - "Our data demonstrated that MrkH played a crucial role in the regulation of biofilm formation by K. pneumoniae. In contrast to carbapenem-sensitive K. pneumoniae, carbapenem-resistant K. pneumoniae was less likely to have strong biofilm-forming capacity because it does not carry the mrkH gene."

Journal • Infectious Disease • Pneumonia

Antibacterial, anti-efflux, anti-biofilm, anti-slime (exopolysaccharide) production and urease inhibitory efficacies of novel synthesized gold nanoparticles coated Anthemis atropatana extract against multidrug- resistant Klebsiella pneumoniae strains. (PubMed, Arch Microbiol) - "Subsequently, the expression of mrkA, wzm and acrB genes was evaluated using quantitative Real-Time PCR (qRT-PCR)...Moreover, the in vitro cytotoxic activity confirmed by MTT assay on the HEK-293 normal cell line showed negligible cytotoxicity. Thus, the present study suggests the potential use of AuNPs in the development of novel therapeutics for the prevention of biofilm-associated K. pneumoniae infections."

Journal • Infectious Disease • Pneumonia • Respiratory Diseases

Progress towards the development of Klebsiella vaccines. (PubMed, Expert Rev Vaccines) - "Vaccines based on other KP virulence factors, such as outer membrane proteins, type 3 fimbriae (MrkA) and siderophores are at earlier stages of development. Novel strategies for the clinical testing of KP vaccines need to be developed."

Journal • Complement-mediated Rare Disorders • Infectious Disease • Pneumonia • Respiratory Diseases

The association of surface adhesin genes and the biofilm formation among Klebsiella oxytoca clinical isolates. (PubMed, New Microbes New Infect) - "...The presence of adhesins was as follows: fimA, 60% (n = 30), mrkA, 42% (n = 21), matB, 96% (n = 48) and pilQ, 92% (n = 46)...The presence of surface adhesin-encoding genes was significantly associated with the biofilm formation and also with resistance to non-β-lactam antibiotics among K. oxytoca clinical isolates. In addition, biofilm production was not significantly associated with β-lactam resistance among the isolates."

Clinical • Journal • Biosimilar

Selective inhibition of Syk Attenuates IGE-mediated bronchoconstriction in human precision cut lung slices (ATS 2012) - MRK-A fully blocked IgE mediated bronchoconstriction in hPCLS (n=4, p=0.0012) & suppressed the release of mast cell mediators from IgE-treated hPCLS in a dose-dependent manner; In contrast, MRK-A had no effect on non-allergic bronchoconstriction induced by cholinergic agonism (n=4); SYK mRNA & protein were not detected in primary human ASM cells

Preclinical-other • Immunology

Investigation of LuxS-mediated quorum sensing in Klebsiella pneumoniae. (PubMed, J Med Microbiol) - "Quantitative RT-PCR evaluated the expression of lipopolysaccharide (wzm and wbbM), polysaccharide (pgaA), and type 3 fimbriae (mrkA) synthesis genes in wild-type and ΔluxS mutant biofilm extracts.Results...Relationships among AI-2-mediated quorum sensing, biofilm formation and gene expression of outer-membrane components were identified in K. pneumoniae. These inter-connected processes could be important for bacterial group behaviour and persistence."

Journal

Antibacterial, antibiofilm, and antiquorum sensing activities of phytosynthesized silver nanoparticles fabricated from Mespilus germanica extract against multidrug resistance of Klebsiella pneumoniae clinical strains. (PubMed, J Basic Microbiol) - "The results of the microtiter plate and RT-PCR methods show that AgNPs inhibited the biofilm formation in MDR K. pneumoniae strains, and the expressions of mrkA and luxS genes were downregulated significantly in MDR strains after treatment with a subminimum inhibitory concentration of AgNPs. In conclusion, AgNPs effectively prevent the formation of biofilms and kill bacteria in established biofilms, which suggests that AgNPs might be a promising candidate for the prevention and treatment of biofilm-related infections caused by MDR K. pneumoniae strains."

Clinical • Journal

Comparison of adhesin genes expression among Klebsiella oxytoca ESBL-non-producers in planktonic and biofilm mode of growth, and imipenem sublethal exposure. (PubMed, Microb Pathog) - "Although none of isolates produced strong biofilm, biofilm conditions led to the increase in the expression of adhesin encoding genes in non-ESBL-producing K. oxytoca. Furthermore, β-lactams; and especially carbapenems possibly increase the colonization of K. oxytoca and increase the biofilm formation. Hence, accurate consumption of antibiotics must be considered."

Journal

Biofilm Formation and Virulence Determinants of Klebsiella oxytoca Clinical Isolates from Patients with Colorectal Cancer. (PubMed, J Gastrointest Cancer) - "Bacterial enteric pathogens possibly play a role in CRC. Biofilm formation by K. oxytoca strains prevents the efficient infection elimination; therefore, rapid identification and control measure are chief requirements. Additionally, more investigations are necessary with this regard."

Clinical • Journal

EtcABC, a Putative EII Complex, Regulates Type 3 Fimbriae via CRP-cAMP Signaling in Klebsiella pneumoniae. (PubMed, Front Microbiol) - "...After crp was deleted in K. pneumoniae STU1 and two clinical isolates, these three crp mutant strains could not express MrkA, the major subunit of the fimbrial shaft, indicating that CRP positively regulated type 3 fimbriae synthesis...We also found via ELISA and the luxCDABE reporter system that overexpression of etcABC increased intracellular cAMP levels and the transcription level of crp, respectively, in K. pneumoniae. In conclusion, overexpression of etcABC positively regulated cAMP production and cAMP-CRP activity to activate the mrk operon, resulting in increased type 3 fimbriae synthesis in K. pneumoniae."

Journal

Expression of adhesin genes and biofilm formation among Klebsiella oxytoca clinical isolates from patients with antibiotic-associated haemorrhagic colitis. (PubMed, J Med Microbiol) - "Bacterial attachment by adhesins and biofilm formation among extensive drug-resistant K. oxytoca isolates hinder the efficient infection eradication. Hence, control and surveillance studies should be performed and other therapeutic auspicious approaches must be taken into account against AAHC, biofilm formation and drug resistance spread. Furthermore, previous antibiotic consumption and long-term hospitalization should be controlled."

Clinical • Journal