Small Pleomorphic Gram Negative Bacilli II Flashcards
Gram – Negative Bacilli:
Related to the Respiratory System
Haemophilus spp.
Legionella spp.
Bordetella spp.
o Group of small, gram-negative, pleomorphic bacteria
o Normal microbiota of mucous membranes
Haemophilus spp.
Haemophilus spp. Growth requirements:
Hematin – from blood
NAD – from yeast extract or Staphylococcus aureus
Pfeiffer’s Bacillus
Infects only humans
Transmission:
- via respiratory route
Haemophilus spp.
Haemophilus spp.
Virulence factors
o Capsule – 6 types type B – most virulent
polyribitol ribose phosphate (PRP)
o IgA1 protease
o Fimbriae
o Membrane CHONS
- Meningitis – 95% by type B
– most common meningitis in aged < 2 y.o.
(5 months to 5 years in the US) - Acute epiglotitis
- Pneumonia
- Septic arthritis in infants
- Sepsis (usually in aspleenic px)
- Others: otitis media, sinusitis
Haemophilus influenzae
- Gram stain
gram – negative short rods or coccobacilli
Haemophilus influenzae
- Culture
- Requires both X and V factors
i. Chocolate agar Plate
ii. Blood Agar Plate next to a streak of beta-hemolytic Staph (Staphylococcus aureus )
iii. Mueller-Hinton Agar that has been
fortified with both X- factor and V-factor
Haemophilus influenzae
- Quellung reaction
- Biochemical tests:
Catalase positiveNon - hemolytic Ferments glucose - Serologic tests – detect capsular PLS
– type – polyribitol phosphate
ex. FAT, ELISA, LPAT
Haemophilus influenzae
Sexually transmitted o Clinical Presentation
Chancroid/Soft chancre
- painful genital ulcer coexisting inguinal lymphadenopat
Haemophilus ducreyi
Laboratory diagnosis
1. Gram stain – small pleomorphic gram negative bacilli in clusters - “school of fish”
Haemophilus ducreyi
Culture
Fresh Clotted Rabbit Blood - preferred
20 – 30% Defibrinated Rabbit Blood agar
Sheep or Horse Blood
Chocolate Agar with 1% IsoVataliX and Vancomycinl
Haemophilus ducreyi
Haemophilus ducreyi
Prevention
– 1 gram oral Azithromyxin
Treatment
◼ Ceftriazone Intramuscular
◼ Oral Ciprofloxacine
◼ Oral Erythromycin
Note
Kock-Week’s Bacillus
Haemophilus aegyptius
Clinical Presentation
- Pink eye conjunctivitis
- Resembles H. influenzae biotype III
Haemophilus aegyptius