Treatment of bacterial infection Flashcards
What are CFUs (quantification)?
CFU = colony-forming unit. This is where bacteria grows in a batch culture and serial dilutions of the culture are performed to work out the type and quantity of bacterial cells present. best used sample is urine.
What is latex agglutination?
Relies on antibodies that are specific for the antigen your testing. the antigen can be something on the surface of the bacteria such as specific proteins, or the actual antibodies your body produces for the antigen.
You coat latex beads covered with the antibody with the antigen, they will clump together when the antigen is present.
What is serology vs serotyping?
Serology = relies on diagnostic identification of antibodies in the serum e.g. latex agglutination (only relevant antigens will be bound by specific antibodies).
Serotyping = determines the sub type of the organism. e.g. salmonella has 2500 serotypes, knowing what is present allows effective treatment.
What are biochemical assays?
They figure out the type of properties the bacteria have . Bacteria have different properties such as living off sucrose but not maltose, and producing different enzymes.
What are advantages and disadvantages of molecular diagnosis?
Adv:
- bacterial genomes are unique
- genetic material can be extracted from infected specimens
- DNA is easy to detect and quantify
Dis:
- technology is still being developed
- some tests are too sensitive
standardisation from lab to lab can be problematic
What is a PCR?
Amplifies the gene of interest, such as bacterial rRNA 16S which is very specific and allows us to identify the species in our sample.
Real time PCR adds fluorescent dye to the sample, the more positive bands we get shows positive corelation.
What are antibiotics?
Mean anti life. they are natural or synthetic compounds that prevent microbial growth. Sadly we are running out and developing more antibiotic resistance, which means the pathogen becomes resistant, not our bodies.
What is happening to 70% of antibiotic production?
Added to animal feeds on farms to prevent infection working up the food chain. This causes a lot of antibiotic resistant strains in the soil and water which will then be taken up by plants and animals. Antibiotic resistance kills 10mil people by year 2050.
What does a static antibiotic do?
Used when the immune system cannot clear the infection. It stops reproduction of the antibiotic, allowing our immune system to catch up and kill the bacteria itself. An example is chloramphenicol.
What does a cidal antibiotic do?
kills invasive and aggressive infections, for example, penicillin.
How do we determine targets for antibiotics?
Things that don’t exist in the human body, so the antibiotic will not harm our own cells. They can target DNA or RNA synthesis, the cell membrane.
What is minimum inhibitory concentration (MIC)?
This is the minimum concentration of antibiotic required to inhibit antigen growth, helping us determine dosage. This is tested in a 96 well plate.
How do we modify approaches for treating infections?
- limit antibiotic use
- last resort antibiotics (polymyxin)
- combination therapy
- phage therapy
- faecal transplant
What do UK Health Protection Teams need to know when there is a suspected outbreak?
- reported by whom and where
- type of suspected outbreak
- who is affected
- populations at risk
What is a lytic antibiotic?
it lyses (bursts) the bacteria by interfering with structural integrity and causing the bacteria to pop.
