Notes in 2- Classification of Bacteria

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Published	02/10/2024	Bacteria - a major group of micro-organisms causing infectious disease.• Drug resistant infections are a major global public health threat.• Mainly si…
Published	02/10/2024	Gram (+) bacteria → {{c1::thick}} peptidoglycan cell wallGram (-) bacteria → {{c1::thin}} peptidoglycan cell wall, periplasmic space, lipopolysacchari…
Published	02/10/2024	{{c1::Peptidoglycan cell walls}} are structures on bacteria that form the basis for gram staining.Purple stain → gram (+) because crystal violets are …
Published	02/10/2024	Why is knowledge of gram staining important?1- Classify clinically important organisms2- Early indication of the genus of bacteria causing infection3-…
Published	02/10/2024	Why is knowledge of gram staining important?
Published	02/10/2024	Classification of Gram (+) BacteriaNutritional & Growth requirements:Aerobic & Anaerobic ----------------------Morphology: {{c1…
Published	02/10/2024	{{c1::Staphylococci}} (clusters) and {{c1::Streptococci & Enterococci}} (chains) are the major genus of aerobic gram positive cocci.
Published	02/10/2024	{{c1::Staphylococcus aureus}} are a coagulase-positive staphylococci i.e. produces the enzyme coagulase.It is a commensal organism carried in nose, ax…
Published	02/10/2024	One of the common characteristics of coagulase-negative staphylococci is the formation of {{c1::biofilms}}i.e. when they adhere to a surface and form …
Published	02/10/2024	{{c1::S. lugdunensis}} is a sneaky coagulase-negative staphylococci that behaves like S. aureus in regards to pathogenesis.{{c1::S. epidermidis}} is a…
Published	02/10/2024	Haemolytic classification of Streptococci: 1- {{c1::a-haemolytic}} (partial haemolysis)→ turn blood agar green2- {{c1::b-haemolytic}} (complete h…
Published	02/10/2024	a-haemolytic streptococci - partial haemolysisTwo important species:1- {{c1::Streptococcus pneumoniae (pneumococcus)}}→ pneumonia, meningitis, septica…
Published	02/10/2024	b-haemolytic streptococci → complete haemolysis• Further identified by carbohydrate surface antigens ({{c1::Lancefield Group}}) → Groups A-G.• A,…
Published	02/10/2024	Group A streptococci e.g. Strep. {{c1::pyogenes}} are major pathogens that cause: - Pharyngitis, cellulitis, necrotising fasciitis (“flesh e…
Published	02/10/2024	Group B streptococci e.g. Strep. {{c1::agalactiae}} are common commensals in genital tract they can cause:1- Neonatal sepsis (vertical&…
Published	02/10/2024	Gram positive bacilli (Aerobic & Anaerboic)[1] {{c1::Clostridiodes/Clostridium difficile}}• “Difficult” to culture.• Asymptomatic gut carriage –up…
Published	02/10/2024	{{c1::Clostridiodes/Clostridium difficile}} are gram positive bacili that are “Difficult” to culture, they spread via spores, which are not …
Published	02/10/2024	1 Staphylococcus aureus2 Streptococcus pyogenes3 Streptococcus pneumoniae4 Clostridium difficileAbove are gram positive bacteria - explain where they …
Published	02/10/2024	{{c1::Infection}} means that germs are in or on the body and make you sick{{c1::Colonization}} means germs are on the body but do not make you sick
Published	02/10/2024	Classification of Gram negative organisms
Published	02/10/2024	75% of the worst bacteria as prioritized by WHO are Gram {{c1::negative}} bacteria
Published	02/10/2024	Gram negative cocci (Neisseria spp) & (Moraxella spp)-------------------[1] e.g. Neisseria {{c1::meningitidis}} (meningococcus)• Meningi…
Published	02/10/2024	{{c1::Septicaemia}} is when bacteria enter the bloodstream, and cause blood poisoning which triggers sepsis. Sepsis is an overwhelming and life-t…
Published	02/10/2024	{{c1::Neisseria meningitidis (meningococcus)}} is a gram negative cocci that causes Meningitis – inflammation of the meninges and …
Published	02/10/2024	{{c1::Coliforms}} are gram negative bacilli organisms which are in the family Enterobacteriaceae they are mainly commensals of the human large intesti…
Published	02/10/2024	{{c1::Escherichia coli}} is a gram negative bacilli that can colonise humans and animals, and they can ferment lactose.Virulence mechanisms (cause dis…
Published	02/10/2024	{{c1::Enterotoxogenic E.coli}} are E.coli responsible for the most common cause of traveller's diarrhoea→ gets in gut through ingestion of contaminate…
Published	02/10/2024	Salmonella spp. → Does not ferment lactose.[1] Salmonella enterica >1500 serotypes.• Whole genome sequencing now performed in reference lab.• …
Published	02/10/2024	{{c1::Coliforms}} are gram-negative bacteria that are always present in the digestive tracts of animals, including humans, and are found in their wast…
Published	02/10/2024	Curved Gram Negative bacilli• {{c1::Campylobacter spp.}}• Microaerophilic – likes low O2• Source is domestic animals and chickens & Spread vi…
Published	02/10/2024	Curved Gram Negative bacilli→ {{c1::Helicobacter pylori}}• Curved rods.• Natural habitat is human stomach. • Damages mucosa and causes ulcers.• S…
Published	02/10/2024	{{c1::Haemophilus influenzae}} is a gram negative cocci-bacilli (mixed) that causes respiratory tract infection.Capsulate form 'type bl vaccine →…
Published	02/10/2024	Gram negative bacilli e.g. (relevant){{c1::Pseudomonas spp}}• Water and soil coloniser – drains, sinks, mops & may contaminate medical equipment.•…
Published	02/10/2024	{{c1::Anaerobes}} are often part of a polymicrobial infection. e.g.[1] {{c2::Prevotella & Porphyromonas}} → Oral cavity• Important in aetiolo…
Published	02/10/2024	{{c1::Pseudomonas spp}} are gram negative bacilli, → water and soil colonisers, hospital acquired cause of sepsis.They are feared as a respirator…
Published	02/10/2024	{{c1::Prevotella & Porphyromonas}} are oral anaerobes that are often part of a polymicrobial infection.They are important in aetiology of per…
Published	02/10/2024	{{c1::Bacteriodes spp}} are one of the most common Gut anaerobes, colonisers of gut flora.They cause intra-abdominal abscesses and may spread to other…
Published	02/10/2024	{{c1::Miscellaneous bacteria}} are bacteria that cannot be stained with Gram’s method due to composition of the cell wall.• Not all bacteria can be cu…
Published	02/10/2024	{{c1::Acid And Alcohol Fast Bacilli (AAFB)}} are resistant to decolourisation by acid or alcohol after staining with carbol fuchsin.e.g. Mycobaterium …
Published	02/10/2024	What's the problem with lab identification of Mycobacteria? i.e. using ZN or Auramine screening stain1- {{c1::Does not identifiy species, only genus}}…
Published	02/10/2024	{{c1::Mycobacterium tuberculosis}} is a miscellaneous bacteria that causes tuberculosis.It can be cultured.
Published	02/10/2024	{{c1::Mycobacterium leprae}} is a miscellaneous bacteria that causes Leprosy.It cannot be cultured and it attacks peripheral nerves.
Published	02/10/2024	{{c1::Spirochaetes}} are long, spiral-shaped miscellaneous bacteria.[1] {{c2::Treponema pallidum}} → Syphilis[2] {{c2::Borrelia burgdorferi}…
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Published	02/10/2024	Syphilis has various stages:{{c1::Primary}} → non-painful skin lesion (chancre) at the site of infection (skin / mucous membrane){{c1::Secondary}} (af…
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Published	02/10/2024	They are miscellaneous bacteria too.
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Published	02/10/2024	The most common Sexually Transmitted Infection (bacterial STI) in the UK is {{c1::Chlamydia}}
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