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L7 - GRAM NEGATIVE BACTERIA
:
Describe the different morphologies…
L7 - GRAM NEGATIVE BACTERIA
:
- Describe the different morphologies amongst GNB
- State the basic laboratory test that define the Enterobacteriacieae
- Recognise which genera of Gram Negative Rods belong to the Enterobacteriacieae
- Name the clinically important species within the Enterobacteriaciea genera and describe the diseases they produce (typically)
- Recognise genera Pseudomonas, Burkholderia, Stenotrophomonas and Acinetobacter as being oxidase positive non-fermenters and describe the typical illnesses produced
6.Describe the nomeclature within the genus Vibrio
- Descrie the diseases typically produced by members of the genera Virioand Aeromonas
Family: ENTEROBACTERIACIEAE
- They utilise glucose fermentatively
- They are NEGATIVE in the Oxidase Test
- Reduce nitrate to nitrite
Inhabit Hospitals/Nosocomial setting
Resistnt to Antibiotics (acquired resistance)
- Debilitated patients
Causes:
a) Urinary Tract Inf.
b)Resp. tract Inf
c) Surgical Wound Inf. -
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Klebsiella
Klebsiella pneumonia
- Community Acquired lobar pneumonia
- Affects - debilitated, aloholic, diabetic with chronic obstructive airways disease
Sever rapid onset, necrotising pneumonia = courrant jelly
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Common Cause of UTI
Proteus mirabilis
=> 2nd most common cause of UTI (behind E.coli and equal to Staphylococcus staphrophyticus)
Genus Citrobacter
Commensal in the Bowel
Within a nosocomial setting, can cause pneumonia and meningitis
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Genus Escherichia
- Commensal of the human bowel
- Uropathogenic strains = UTIS
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Diarrhoeal Illness
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Genus Shigella
- Cause bacterial dysentry diarrhoeal stool contains pus +blood
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Non typhoidal Salmonella = Self limiting Diarrhoea
Ubiquitous commensal in animals, and cause non-specific symptoms after individual is in contact with contaminated food
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Plague
Genus Yersinia
Yersinia pestis
- Found commonly in Rats, infection transmitted by rat fleas
- 1/4 Euro's pop during Middle Ages
- Madagascar had recent endemic >2000 cases (~2017)
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Yersinia enterocolitica
- Infects colon => ulcer
- Infects mesenteric lypmh nodes => mesenteric adenitis => pseudoappendicitis
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NON- FERMENTATIVE GN RODS
-Don't metabolise glucose by fermentative pathways (or don't utilise it at all)
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U.T.I.'s
Pseudomonas aeruginosa
Nosocomial setting
Very common pathogen, most prominent cause for inf. in this group of non-ferm.
Inherent antibiotic resistance
- UTI's (particularly in a nosocomial setting (indwelling catheter left unattended)
RESPIRATORY INFETIONS
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Burkholderi pseudomallei
Tropical infection
- Found SE Asia + N. Australia
- Exists in soil, infectious through abrasions + inhalation
ANTIBIOTIC RESISTANCE (inherent)
Melioidosis
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- Septicaemia (high fatality
Genus Acinetobacter
- Ubiquitous in soil and aquatic enviroments
- Colonisers of human skin and Resp. Tract (commensal)
NOSOCOMIAL opportunistic inf. => Antibiotic resistance
Acinetobacter baumanii
- Community acquired pneumonia (from smoking, Pulm. disease, diabetes)
- Immunocompromised =>pneumonia, IV catheter bacteraemia/UTI
Acinetoacter Iwofii
- Immunocompromised =>pneumonia, IV catheter bacteraemia/UTI
Pseudomonas aeruginosa
- Nosocomial setting
- Very common pathogen, most prominent cause for inf. in this group of non-ferm.
- Inherent antibiotic resistance
- Heightens risk of patients with lung inf. =>CYSTIC FIBROSIS
- Those debilitated hosp. patients (mechanically ventilated) => lung inf.
- May cause SEPTICAEMIA in leukaemia, IV drug users, and those with organ transplants
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OXIDASE POSITIVE FERMENTERS
- Staining based test incorporating Oxidase pathway of ETC
Genus Vibrio
Diarrhoeal Causing-Only strains producing cholera toxin
- Epidemic/pandemic
- high fatality
Vibrio cholerae (certain strains)
- Diarrhoea => Sever dehydration => Hypotensic shock => Death
Vibrio Cholerae
- Typed based on antigenic diff.
- type-01 V. cholerae (more virulent)
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Klebsiella granulomatis
NOT NOSOCOMIAL
Sexually transmitted infection, common in the tropics
- Donovanosis => soft tissue inf. ulcer = worsens to destroy tissue
- Chronic and disfiguring
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