MICRO: - BACILLI (FASTIDIOUS GNB) Flashcards
Why are the fastidious species termed fastidious?
They have complex or specific nutritional requirements
- require increased carbon dioxide environment
- Special nutrients/ growth factors
When testing for the presence of a fastidious organism, relying on culture alone is not effective because…
negative culture results may be false negative
Other options to use other then culture to test for presence of fastidious organism?
serology, molecular tests
Shape of fastidious species
coccoid or coccobacilli
The smallest of all gram negative bacterias?
Fastidous GNB
Why using a microscope on fastidious species may not be appropriate?
Fastidious species fail to discolourise completely on the gram stain, they faintly stain
Fastidous GNB are________signaling that they vary in size/shape/ staining
pleomorphic
The five fastidious GNB species
-Haemophilus Influenzae
- HACEK organisms
-Pasteurella species
-Bordetella Pertussis
-Legionella spp
-Capnocytophaga spp.
The name Haemphilus influenza tells us the bacteria is_______
Blood loving
A small, pleomorphic coccobacilli or rods species____
Haemophilus influenzae
Part of the normal flora of upper respiratory tract in most adults and rarely cause disease
Haemophilus influenza
Hemophilus influenza species associated with humans
- H influenzae
- H ducreyi
how is haemophilus influenza spreads?
-Through direct contact
- respiratory secretions/droplets
(note: Does not cause influenza flu)
Major virulence factor of H. Influenzae
Polysaccharide Capsule
Important sources of dissemination for H influenzae?
-families
- and daycare centres
Other important virulence factors of H influenzae?
- Fimbriae
-Immunoglubulin A protease - Outer membrane proteins and lipopolysaccharide
Which H influenzae strains cause most invasive infection?
The encapsulated strains (Type B)
Most common invasive disease from haemophilus influenza encapsulated strains?
meningitis
(Pneumonia and bacteremia occur in older children and adult with underlying disease)
Invasive diseases from encapsulated H. Influenza strains?
Septicemia, meningitis, arthritis, epiglottitis, pneumonia
T/F: Non-encapsulated H. Influenza cause invasive disease only on immunocompromised patients.
True
Non-invasive diseases from non-encapsulated H influenza strains?
otitis media, sinusitis, conjuctivitis
H. Influenza growth requirements as it’s one of the fastidious spp?
Requires growth factors present in RBCs.
X factor (unknown factor)- hemin or hematin
V factor (vitamin)- NAD
- H influenza requires chocolate agar for recovery of the species from clinical specimens
- Grow better in CO2
Require environment rich in CO for optimum growth
-HACEK org
Fastidious species forming part of normal human flora of oral cavity
HACEK org
HACEK are non-invasive oral flora org. Two ill practices can introduce these organisms into your blood stream. These are_____and _____
- Poor dental hygiene
- Oral surgery
T/F: HACEK can cause opportunistic infections on the immunocompromised
True
The pleomorphic GNB with pibolar staining( ends of the bacilli stain more intensely than the middle).
Pasteurella species
A fastidious GNB requiring high CO2 , with some species requiring a V factor
Pasteurella species
The most common Pasteurella species causing disease in human?
Pasteurella multocida
Where is the Pasteurella multocida found on living organisms? Like its habitat
-Mouth /GI and Respiratory tract of healthy animals (esp cats, dogs, horses, cattle etc)
How are human infected with Pasteurella multocida?
Through animal bites
- Humans present with skin/soft tissue infection following animal bites.
Upon animal bites and infection with Pasteurella multocida. The infection can rarely cause______
-Lung abscesses, empyema, septicaemia…
Also a tiny gram negative coccobacilli
Bordatella pertussis
How is Bordatella Pertusis transmitted?
Inhalation of highly infectious respiratory droplets—the disesase then colonises the respiratory mucosa
Outcome from infection with Bordatella pertusis
-Damaged ciliated epithelium from bacterial toxins
-Whooping cough
Preferrable daignoses of bordatella pertusis?
PCR
Preventative strategy of bordatella pertusis
Vaccine
Fastidious GNB which lives in aquatic bodies- rivers, streams, air conditioner, water coolers?
Legionella spp. (L. Pneumophilia)
Mode of transmission of legionella spp?
Inhalation of contaminated aerosol
A fastidious spp which causes pontiac fever, legionnaires disease, a rapidly progressive pneumonia?
Legonella spp
fastidious species requiring specialised media containing iron and cysteine?
The species is slow growing
Legionella spp
Diagnoses of Legionella is through?
Molecular identification methods: PCR
Majority of this species are part of the normal flora of human oral cavity?
Capcytophaga spp
Thin, spindle shaped GNB with pointed ends, requiring increased CO2 for growth?
Capnocytophaga
Can cause the sever illness in individuals with asplenia;
And Septicaemia in neutropenic patients
encapsulated capnocytophaga
Source of oral ulcers?
capnocytophaga spp
