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Divine infection > Key Bacteria - Others > Flashcards

Key Bacteria - Others Flashcards

1
Q

List the 6 other key Bacteria

Other than Staph or Strep

A
  • Clostridium difficile (only +ve one in this list)
  • Neisseria meningitidis
  • E. coli
  • Haemophilus influenza
  • Salmonella typhi
  • Legionella pneumophilia
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2
Q

Describe structure of Clostridium difficile

A
  • Gram +ve, Baccili bacteria
  • Obligate Anaerobe
  • Sporulative
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3
Q

Where is C. difficile normally found?

A

Normal commensal in the bowel

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4
Q

How does C. difficile infection spread?

A

Contagious spread

  • Spores (persistent in environment)
  • contact with infected patient’s vomit/diarrhoea
  • Very clinically key HAI
  • linked to antibiotic use
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5
Q

Commonly linked conditions to C.difficile infections?

A
  • Pseudomembranous colitis
  • diarrhoea
  • vomiting
  • C.difficile infections tend to be preceded by other infections requiring antibiotic treatment.
    — C.diff linked to antibiotic use. Antibiotics act as selection pressure, kill competition in bowel, however C.diff is resistant and survives and proliferates causing infection.
    — key Antibiotics linked to C.diff = Ceftriaxone & Ciprofloxacin
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6
Q

Virulence factors of C.difficile

A

Production of Enterotoxins:
- Toxin A = causes inflammation and buildup of excessive fluid secreted in bowel

Production of Cytotoxins:
- Toxin B = causes disrupted formation of cell cytoskeleton

Also has a Dispensable flagellum

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7
Q

Investigations for C.diff infection?

A
  • culture from stool sample
  • enzyme immunoassay
  • FBC
  • CRP
  • Gram stain = +ve baccili
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8
Q

Treatment for C.diff infection?

A

Infection control = PPE, hand-washing, sterile/aseptic technique

Supportive treatment = fluids to re-hydrate

Specific treatment = oral antibiotics

  • Metronidazole (mild cases)
  • Vancomycin (severe cases)
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9
Q

Describe the structure of Neisseria Meningitidis?

A
  • Gram -ve, cocci bacteria
  • Diplococcus bacteria
  • Encapsulated
  • Numerous serogroups - E.g. A,B,C,W-135

(Different serogroups are based on the polysaccharide capsular antigen.) (Most cases due to group B (1000 cases/yr))

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10
Q

Where is Neisseria meningitidis found normally?

A

Nasopharyngeal mucosae of healthy carriers.

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11
Q

How can Neisseria meningitidis spread?

A

Contagious spread person to person

  • Spread by direct contact with respiratory secretions - E.g. Aerosols, Nasopharyngeal secretions
  • via inhalation of droplets.

Infection can also occur from movement of N. meningitidis to other parts of the body.

Infection more common in places where lots of people are living in close proximity (e.g. halls of residence, army barracks etc.)

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12
Q

Commonly linked conditions to N. meningitidis infection?

A

Sepsis = Infection can occur if Neisseria meningitidis in nasopharynx breaches epithelial barrier and enters blood stream

Meningitis = An infection of meninges of the brain, which affects the brain membrane. (If it crosses blood/brain barrier)

(Most common in teenage / young children)

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13
Q

Meningitis clinical presentation?

A
  • Purpuric rash
  • Photophobia
  • Neck stiffness
  • Fever (rapid onset)
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14
Q

Virulence factors of N. meningitis?

A
  • Encapsulated (lipopolysaccharide capsule)
    = Anti-phagocytic
    = Outer membrane acts as an endotoxin
  • Pili
    = Allows attachment/adhesion to nasopharyngeal mucosae
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15
Q

Investigations for N. meningitidis?

A
  • Full blood count
  • CRP = indicated general inflammation
  • Urea & Electrolyte = investigation for sepsis
  • lactate = investigation for sepsis
  • Clotting factors
  • Blood culture = detect Bacteraemia
  • ALT & AST = liver function test
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16
Q

Prevention for N. meningitidis infection?

A

Prevention — Vaccination —

  • Meningococcal C conjugate vaccine
  • ACWY vaccines
  • Serogroup B vaccines

Prevention — Antibiotic Prophylaxis

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17
Q

Treatment for N. meningitidis infection?

A

If high fever and non-blanching rash = Antibiotics given straight after history, before test results.

Antibiotics —

  • Penicillin
  • ampicillin
  • Caftriaxone
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18
Q

Describe the structure of Escherichia coli (E. coli)?

A

Gram -ve, Bacilli bacteria.

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19
Q

Where is E. coli normally found?

A

Normal commensal of the bowel

Faecal-peritoneal route

20
Q

How does E.coli spread?

A

Faecal-oral route

  • contaminated food or water
  • person to person
  • vertical transmission (mother to child during birth)
21
Q

Commonly linked conditions to E. coli infection?

A

Diarrhoea

Peritonitis / Pancreatitis

  • perforation of the bowel = E.coli enters & infects the peritoneum or infects the pancreas.
  • Presentaton = bloody diarrhoea, tender abdominal

Septicaemia

  • perforation of the bowel —> E.coli enters blood stream
  • clinical presentation sepsis = fever, shock, L.O.C, organ failure

UTI

  • faecal matter enters urethra
  • most likely in females due to anatomically shorter distance between anus and urethra
  • clinical presentation = dysuria, inc. frequency & urgency of urine, pain when urinating
  • if occurs in males = tends to be more severe

Neonatal meningitis
- vertical transmission (mother to baby) during birth

22
Q

Virulence factors of E.coli?

A

Pili = adhesion = allow the binding of E.coli to a surface liposaccharide

23
Q

Investigations for E.coli infections?

A

UTI = urine dip stick test

  • Nitrite test = positive (due to reduction from nitrates)
  • leukocytes esterase = positive (due to release by release by leukocytes and macrophages, causing pyuria (pus in urine)

Blood culture = testing Bacteraemia & septicaemia
FBC
CRP
Stool sample

24
Q

Treatment for E.coli?

A

Prevention = care in selection, preparation & consumption of food and water.
- hygiene, hand-washing etc.

ORH????

Supportive = fluids to rehydrate = compensate water loss

Specific = antibiotics

  • UTI = trimethoprim (inhibits folic acid synthesis) (don’t give pregnant women or anyone already folate deficient)
  • Severe gram -ve sepsis = gentamicin
  • neonatal meningitis = cefotaxime
25
Q

Describe structure of Haemophilus influenzae?

A

Gram negative Cocco-Bacilli

26
Q

Where is Haemophilus influenzae normally found?

A

Can be a nasopharyngeal commensal in healthy individuals

27
Q

How is Haemophilus influenzae spread?

A

Community acquired.

  • Contagious spread after colonisation of respiratory tract.
  • Inhalation of droplets (usually via coughs & sneezes)
  • opportunistic infection
28
Q

Commonly linked conditions to H. influenzae?

A

Community acquired (usually opportunistic) infection especially in children

  • pneumonia
  • Meningitis in infants
  • ENT infections = otitis media, sinusitis and epiglottitis
  • Septicaemia = in blood
29
Q

Virulence factors of H. influenzae?

A
  • Capsule = Resists phagocytosis
  • Adhesins = aid adhesion for infection
  • Pili = aid adhesion for infection
  • IgA1 protease = proteolytic enzyme, destroy the structure and function of human IgA1 antibodies
  • Lipooligosaccharide = glycolipids cell-surface antigen found in the outer membrane of some types of Gram -ve bacteria, interact with host epithelial cells, triggering inflammatory response.
30
Q

Investigation for H. influenzae infection?

A
  • culture on blood agar
  • gram stain = gram -ve Cocco-bacilli
  • blood culture
  • FBC
  • CRP
31
Q

Treatments for H. influenzae infection?

A

Supportive
Pneumonia = fluids, ibuprofen for treating inflammation

Specific = antibiotics
- Ceftriaxone = (monitor use = bcos linked to C.diff)

Prevent = vaccine (e.g. Hib vaccine)

32
Q

Describe the structure of Salmonella typhi?

A
  • Gram -ve
  • Bacilli bacteria
  • Flagellated
  • Facultative anaerobes (can use both aerobic or anaerobic respiration)
33
Q

Where is salmonella usually found?

A
  • not a natural commensal
  • Colonisation of the Reticuloendothelial system
  • Some individuals who are infected with S. typhi become life-long carriers that serve as the reservoir for these pathogen
34
Q

How is S. typhi spread

A
  • Faecal-oral route (contaminated food & water)
  • Undercooked meat e.g. chicken
  • elderly & children at inc. susceptibility

In Systemic form:

  • Salmonellae pass through the lymphatic system of the intestine into the blood of the patients (typhoid form).
  • And are then carried to various organs (liver, spleen, kidneys) to form secondary foci (septic form).
35
Q

Commonly linked conditions to S. typhi?

A

Enteric fever
Typhoid fever
Travel-related infection
Gastroenteritis

Clinical presentation (common)

  • sudden onset of a high fever
  • Diarrhoea & vomiting
  • loss of appetite
  • splenomegaly (depending on where it is located)
  • Sepsis = S.typhi travel through blood and infect other organs
  • Septic & hypovolaemic shock = vasodilation & loss of water & electrolytes from D&V = decr. Blood volume
36
Q

virulence factors for S. typhi?

A
  • Flagella = motile
  • Ferments glucose = produce acid and gas
  • Catalase positive
  • Invasin = protein that allows non-phagocytic cells to uptake the bacterium, and allows it to exist intracellularly. This protects it from the innate immune system.
  • Endotoxins first act on the vascular and nervous apparatus, resulting in:
    • increased permeability and decreased tone of the vessels
    • upset of thermal regulation
    • D & V
37
Q

Investigations of S.typhi infections?

A

Culture on MacConkey agar with typhoid:

  • blood sample
  • bone marrow sample
  • urine sample
  • stool sample
  • tissue sample

Liver function test = raised LFTs = signify liver inflammation/dysfunction

Moderate anaemia

Serology not reliable

38
Q

Treatment for S.typhi infection?

A

Prevention =

  • Enteric fever vaccine
  • Typhoid vaccine

Supportive =

  • fluids compensate for D&V
  • If shock = give oxygen, fluids

Specific = antibiotics
- Ceftriaxone = cell wall synthesis inhibitor
- 3rd Gen cephalosporins =
— Ciprofloxacin = Nucleic acid synthesis inhibitor

39
Q

Describe the structure of Legionella pneumophila

A
  • Gram -ve
  • Bacilli = rods (L.pneumophila = slender rods)
  • Pleomorphic = can alter its size & shape in response to environment
  • Unencapsulated = no capsule
40
Q

Where is L. pneumophila normally found?

A
  • Within environmental biofilm

- accumulates on surfaces (e.g. shower heads)

41
Q

How does L. pneumophila spread?

A
  • Inhalation of contaminated aerosols
  • Within environmental biofilm = therefore surface to person
  • Aspiration of contaminated water e.g:
    - Showers (contaminated as it passed through shower head)
    - Swimming (L.pneumophila survives chlorine and water
    treatment)
42
Q

Commonly linked conditions to L. pneumophila?

A
  • Legionnaires disease
  • Acute lobar Pneumonia = more common in immunosuppressed patients
  • Pontiac fever = more common in healthy individuals
43
Q

Virulence factors of L. pneumophila?

A
  • Fastidious = has very specific nutrient & environmental requirements to grow
  • Monotrichous = has a single Flagellum = motile
  • Lipopolysaccharide = endotoxin
  • Pili = aid adhesion
44
Q

Investigations for L. pneumophila?

A
  • Culture on specialised medium
  • Gram stain = gram -ve bacilli (slender rods)
  • CRP
  • FBC
45
Q

Treatment of L.pneumophila?

A

Management = isolate patient (aerosol spread)

Pontiac fever —
Supportive treatment = Ibuprofen (inflammation symptoms)

Pneumonia —
Specific treatment = antibiotics
- Macrolide = Clarythromycin = inhibits protein synthesis
- Quinoloes = Levofloxacin = inhibits Nucleic acid synthesis

Divine infection (6 decks)

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