The document discusses Escherichia coli (E. coli) and antimicrobial resistance. It describes E. coli, genes that can make it resistant to colistin (mcr-4, mcr-5, mcr-6, mcr-9), and the objectives of investigating antimicrobial resistance in broiler chickens. It outlines methods used like PCR, MIC, MLST, and antimicrobial susceptibility testing. Results shown include PCR gel images and a phylogenetic tree. The discussion evaluates studies on detecting colistin resistance and trends in resistance gene prevalence. It concludes that molecular biology techniques like MLST and PCR are important for understanding and tracking antimicrobial resistance by identifying genes and strains.

1. Gwyneth Lorena Serna Salazar
Tercer semestre
Universidad Pontificia Bolivariana

2. Introduction
What is escherichia coli?
Escherichia coli (E. coli) is a bacterium that normally lives in our
intestines and those of other animals. Most of the time it does
not cause problems and, in fact, is useful in digestion and the
production of some vitamins. However, some strains of E. coli
can make us sick. These strains can cause gastrointestinal,
urinary tract, respiratory, wound and other infections. Some of
these strains produce toxins that can cause serious illness.

3. Genes mcr-4, mcr-5, mcr-6, and mcr-9
The genes mcr-4, mcr-5, mcr-6, and mcr-9
encode proteins that modify the
lipopolysaccharide in the outer membrane
of gram-negative bacteria, preventing
colistin from binding and exerting its
antibacterial effect. This modification
reduces the affinity of colistin for the
bacterial membrane, leading to bacterial
resistance to this antibiotic.

4. general objectives
1- Investigate the prevalence of antimicrobial-resistant
bacteria in broiler chickens in Malaysia.
2- Determine the antimicrobial resistance profiles of the
isolated bacteria.
3- Identify the antimicrobial resistance genes present in the
isolated bacteria.

5. Métodos
Capacidad más baja de agente
antimicrobiano necesaria para detener
el crecimiento de un microorganismo.
Importante para evaluar la
sensibilidad de un microorganismo y
dar un tratamiento adecuado.
Técnica molecular que amplifica
segmentos específicos de ADN,
permitiendo identificar los genes
relacionados con la resistencia a
antibióticos.
PCR MIC

6. Métodos
Capacidad de un microorganismo para
ser inhibido o eliminado por un
antimicrobiano. En este estudio se
utilizó para evaluar resistencia de las
cepas de E. Coli.
La MLST se usa para caracterizar
bacterias como E. coli resistentes a
colistina. Se identificaron linajes
principales y se estudió cómo se
dispersan en distintas fuentes, como
cloacas y agua potable.
MLST Susceptibilidad antimicrobiana

7. Resultados
Imagen de electroforesis en gel
recortada del producto PCR
amplificado de los genes Pho E. Coli
Imagen recortada de electroforesis en gel
del producto PCR amplificado con los
genes mcr-1, mcr-4 y mcr-5.

8. Resultados
Imagen recortada de electroforesis en
gel del producto PCR amplificado con
los genes mcr-6, mcr-8 y mcr-9.
Imagen de electroforesis en gel de agarosa
de la tipificación filogenética de E. coli mcr
positiva.

9. Discussion
Author what the author said agree/disagree
Hindler JA et al. The susceptibility test for colistin by disc
diffusion and E-test is difficult due to
polymyxins’ poor agar diffusion.
Zhang W et al.
Recently, following the ban of colistin use
as food additive in food animals in many
countries, the prevalence of mcr-1 gene
positive bacteria in food animals,
including chickens has decreased.
Liu YY et al. Nonetheless, PCR is widely considered as
the gold standard method in detecting
colistin-resistance.

10. Conclusions
1. Molecular biology, such as MLST, helps to track the spread of antimicrobial
resistance in bacteria such as E. coli.
2. Antimicrobial susceptibility is crucial for determining the efficacy of treatments
against resistant strains, which guides clinical decisions.
3. Molecular biology identifies resistance genes and characterizes resistant strains,
key to understanding and controlling antimicrobial resistance.

11. Mapa conceptual