Related Experiment Video

Updated: Jan 27, 2026

Generation of Enterobacter sp. YSU Auxotrophs Using Transposon Mutagenesis
13:31

Generation of Enterobacter sp. YSU Auxotrophs Using Transposon Mutagenesis

Published on: October 31, 2014

14.4K

PmrAB and PhoPQ Variants in Colistin-Resistant Enterobacter spp. Isolates in Korea

Yoon-Kyoung Hong1, Kwan Soo Ko2

  • 1Department of Molecular Cell Biology and Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.

Current Microbiology
|March 21, 2019
PubMed

Insights

Colistin resistance in Enterobacter cloacae may not involve common PhoPQ and PmrAB gene variations. Further research is needed to understand resistance mechanisms in this bacterium.

Area of Science:

  • Microbiology
  • Genetics
  • Antimicrobial Resistance

Background:

  • Colistin is a critical antibiotic for treating multidrug-resistant Gram-negative infections.
  • Enterobacter cloacae is an opportunistic pathogen frequently associated with healthcare-associated infections.
  • Mechanisms of colistin resistance in Enterobacter cloacae are not fully elucidated.

Purpose of the Study:

  • To investigate amino acid variations in PhoPQ and PmrAB two-component regulatory systems.
  • To analyze mRNA expression of PhoPQ and PmrAB systems in colistin-resistant Enterobacter cloacae.
  • To compare genetic profiles of colistin-resistant, susceptible, and skip-well Enterobacter cloacae isolates.

Main Methods:

  • Sequencing of phoP, phoQ, pmrA, and pmrB genes in 51 colistin-resistant, 5 colistin-susceptible, and 8 skip-well isolates.
  • Analysis of corresponding amino acid sequences.
  • Assessment of mRNA expression levels for phoQ and pmrB.

Main Results:

  • Significant amino acid variations were observed in PhoPQ and PmrAB systems across isolates.
  • No distinct amino acid substitutions were uniquely associated with colistin resistance.
  • mRNA expression of phoQ and pmrB was not significantly elevated in colistin-resistant isolates.
  • Phylogenetic analysis revealed distinct clades for resistant and susceptible isolates.

Conclusions:

  • The study suggests that common mutations in PhoPQ and PmrAB systems may not be the primary drivers of colistin resistance in Enterobacter cloacae.
  • Colistin resistance mechanisms in Enterobacter cloacae might differ from those observed in other Gram-negative bacteria.
  • Further investigation into alternative resistance pathways is warranted.

More Related Videos

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example06:52

Characterizing Herbivore Resistance Mechanisms: Spittlebugs on Brachiaria spp. as an Example

Published on: June 19, 2011

14.2K
Using RNA-sequencing to Detect Novel Splice Variants Related to Drug Resistance in In Vitro Cancer Models09:58

Using RNA-sequencing to Detect Novel Splice Variants Related to Drug Resistance in In Vitro Cancer Models

Published on: December 9, 2016

14.3K

Related Concept Videos

Histone Variants at the Centromere02:30

Histone Variants at the Centromere

Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3...
5.0K
Resistivity01:22

Resistivity

When a voltage is applied to a conductor, an electrical field is generated, and charges in the conductor feel the force due to the electrical field. The current density that results depends on the electrical field and the properties of the material. In some materials, including metals at a given temperature, the current density is approximately proportional to the electrical field. In these cases, the current density can be modeled as:
4.5K
Resistance01:19

Resistance

When a current moves through any conductor, the conductor causes some level of difficulty for the current to flow. The measure of that difficulty is known as the resistance of the material and is represented by R. Every material has its own resistance. In the case of conductors, heat is emitted whenever a current passes through them. Resistance depends on the resistivity of the material. Resistivity is a characteristic of the material used to fabricate electrical components, whereas the...
5.9K
Resistance and Conductance01:25

Resistance and Conductance

A conductor's DC resistance at a given temperature is influenced by its resistivity, length, and cross-sectional area. Resistivity is an inherent property of the conductor material, with annealed copper serving as the international standard for measurement. For instance, the resistivity of hard-drawn aluminum at 20 degrees Celsius is 61% of the standard conductivity of annealed copper.
Various factors impact the resistance of a conductor. Spiraling in stranded conductors increases their...
508
Equivalent Resistance01:16

Equivalent Resistance

In circuit analysis, situations often arise where resistors are neither in series nor parallel configurations. To tackle such scenarios, three-terminal equivalent networks like the wye (Y) (Figure 1 (a)) or tee (T) and delta (Δ) (Figure 1 (b)) or pi (π) networks come into play. These networks offer versatile solutions and are frequently encountered in various applications, including three-phase electrical systems, electrical filters, and matching networks.
976
Vascular Resistance01:20

Vascular Resistance

Vascular resistance is a critical concept in understanding blood flow dynamics in the circulatory system. It refers to the resistance that blood encounters as it flows through the blood vessels. This resistance is a key factor in determining blood pressure and cardiac workload.
The primary determinants of vascular resistance are vessel diameter, blood viscosity, and vessel length. Among these, vessel diameter plays the most significant role due to the fourth power relationship described by...
10.7K