The theory behind AMR

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1. Background of AMR

Which bacteria have natural resistance and
how does antibiotic resistance develop?

2. Mechanisms of bacterial resistance to antibiotics

A summary of the type of resistance and a detailed description of the mechanisms that can be detected by the AMRDetecTool

3. Spread of resistance

from bacteria to bacteria & from patient to patient
& and how to avoid or reduce this

4. Multiresistant bacteria that can be detected by the device

ESBLs: CTXM – MULTI, Carbapenemases: KPC, OXA, VIM, IMP, NDM
VAN A/B, OXA-Ab, 3GC

5. The detection of resistance

The possible methods and why LFIA is good

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Background of AMR

I tētahi ahiahi, e whakareri ana a Māui me ōna tuākana i tētahi hāngi, hai hākari mā rātau. Kātahi anō ka mutu ake te whakawera i ngā kōhatu, ka tō te rā, ka pōuri rawa mō rātau. Ka hōhā a Māui ki te kai i ana kai i roto i te pōuri, ka tū a ia ki te mura o te ahi, ka kōrero atu ki tōna iwi.

Mechanisms of bacterial resistance to antibiotic

“Ia rā me tere tonu tātau ki te mahi i ā tātau mahi, ki te rau ake i ā tātau kai i mua i te tōnga o te rā. He aha i pēnei ai tātau? Māku e hopu te rā i mua i tōna maranga ake, māku tonu e tohutohu te rā, kia āta haere noa tōna ara whakawhiti i te rangi!”

https://jcm.asm.org/content/54/10/2436

 

Spread of resistance

From bacteria to bacteria:

From patient to patient:

Multiresistant bacteria that can be detected by the device

ESBL-s: CTX-M MULTI

ESBL (extended-spectrum beta-lactamase) production is becoming more common among Enterobacteriales.

The CTX-M-type extended-spectrum β-lactamase variants are the most frequently identified ESBLs.

ESBLs hydrolyze:

  • penicillins
  • 2nd, 3rd and 4th generation cephalosporins
  • aztreonam
  • (not cephamycins and carbapenems)

Carbapenemases: KPC, OXA, VIM, IMP, NDM

Carbapenemase production is more and more commonly reported in K. pneumoniae and has also been identified in other gram-negative pathogens including Pseudomonas aeruginosa.

Carbapenemases are beta-lactamases with versatile hydrolytic capacities.

Carbapenemases hydrolyze:

  • penicillins
  • cephalosporins
  • monobactams
  • carbapenems

Klebsiella with plasmid-mediated carbapenem resistance is a significant risk to hospitalized patients. The transfer of these resistance plasmids into E. coli is a significant public health threat because resistant E. coli may become part of the normal gut flora and thereby would be a source of infections in healthcare settings and the community. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3086234/)

VAN A/B: vancomycin-resistant Enterococci

Enterococci tend to persist in hospital environments, allowing for dissemination of resistance elements.

They are common colonizers.

Infections usually occur in immunosuppressed patients who have received multiple antibiotic treatments in the past.

Typically infection may be caused by enterococci:

  • urinary tract infections
  • intra-abdominal and pelvic infections
  • skin and skin structure infections
  • endocarditis
  • central nervous system infections (rarely)

High risk of infection:

  • chronic dialysis treatment
  • severe underlying disease
  • immunosuppressed condition
  • use of invasive devices
  • long hospital care
  • previous or current antibiotic therapy

Van A is responsible for most of the human cases of VRE around the world and is mostly carried by E. faecium. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4521680/)

Enterococci carriers of VAN A gene are resistant to vancomycin and also teicoplanin, but the carriers of VAN B can be susceptible to teicoplanin.

OXA-Ab: OXA-type carbapenemases in Acinetobacter sp.

Acinetobacter species are significant pathogens in hospital-acquired and healthcare-associated infections worldwide.

Acinetobacter spp. may cause:

  • ventilator-associated pneumonia
  • bloodstream infection
  • wound infection
  • urinary tract infection

A. baumannii can develop resistance to multiple classes of antimicrobial agents.
The bacterium can be found anywhere in the hospital environment, can survive on dry surfaces for prolonged periods, often causes protracted outbreaks.

Risks of infection:

  • stay in intensive care units
  • burn injuries
  • traumatology patients
  • ventilated patients
  • immunosuppressed condition
  • serious underlying disease (chronic lung disease or diabetes mellitus)

3GC: third-generation cephalosporin resistance

3GC device for detection of determinants conferring third-generation cephalosporinase resistance (ESBLs (VEB, PER, GES, TEM, SHV), plasmid-encoded cephalosporinases (CMY, DHA)

Cephalosporins allow treating a variety of bacterial infections. Cephalosporin allergy is rare, and they generally cause few side effects. But the resistance against them is increasing continuously.

 

      The detection of resistance

      I te rā o muri ake, ka haere a Māui me tōna whānau ki te kohi i ngā harakeke katoa, ka whakaakongia e Māui tana whānau ki te whiri taura harakeke, i akona e ia i a ia i Rarohenga. Ka hangaia e rātau he tuamaka, he pāraharaha, ka kōwirihia e rātau ngā taura kia noho porowhita ai ngā taura. Ka pau ngā rā e rima ka reri ngā taura, ka rere ngā karakia a Māui ki runga i ngā taura nei. “Taura nui, taura roa, taura kaha, taura toa, taura here i a Tamanuiterā, whakamaua kia mau kia ita!”

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