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
Formerly Haemophilus vaginalis
• Clinical Presentation
- Causes Bacterial vaginosis
(foul smelling vaginal discharge –fishy odor, pruritus and dysuria)
Gardnerella vaginalis
Laboratory Diagnosis
1. Stains
i. Papanicolaou’s stain
“clue cells”
ii. Gram stain –gram variable or gram negative small coccobacilli
Gardnerella vaginalis
Laboratory Diagnosis
3. Culture: Human Blood Tween Agar at 48 hours in 5 – 10% CO2 – Beta hemolysis
V (vaginalis) Agar
4. Whiff Test or Sniff Tests – vaginal discharge + 10% KOH
Positive test – Fishy- amine like odor
Gardnerella vaginalis
Gram – negative aerobic bacilli
Associated with environmental water sources systems
Legionella spp.
Legionella spp.
Important species
- Legionella pneumophila.
-Legionnaire’s Pneumonia
-Pontiac Fever - Legionella micdadei
Pittsburg pneumonia
• Transmission
– Respiratory system
• Laboratory Diagnosis
- Stains
i. Gram stain – stains faintly
– noted be intracellular organisms
Legionella pneumophila
Legionella pneumophila stain
Immunofluoresacence
Dieterle Silver Stain
- Does not grow on ordinary media
- Requires high concentration of Iron and Cysteine
Legionella pneumophila
Legionella pneumophila
Culture media
i. Buffered Charcoal Yeast Extract Agar (BCYE)
- supplemented with L – cyteine, ferric salt and alpha ketoglutarate
ii. Chocolate agar
iii. Feeley-Gorman Medium (brown pigment)
• Strictly aerobic
• Non–fermentative
• Smallgram–negativecoccobacilli
Bordetella spp.
Growth requirements: Bordetella spp.
Growth requirements: - Nitotinic acid
- Cysteine
- usually methionine
• Also added to the medium – remove excess fatty acids
– blood, charcoal, starch or ion exchange resins
Bordetella spp.
Clinically important species
- Bordetella pertussis – Whooping cough
- Bordetella parapertussis
- Bordetella bronchiseptica – Kennel cough in dogs
- patient is highly infective
- susceptible to antibiotic
Phases: 1. Catarrhal phase (1-2 weeks
antibiotic not effective
Paroxysmal phase (2 -10 weeks)
Bordetella pertussis
Virulence factors
- Capsule
- Beta – lactamase producing
- Pili (Filamentous hemagglutinin)
- Toxins
- Pertussis toxin
- Tracheal cytotoxin
With associated lymphocytosis
Bordetella pertussis
Bordetella pertussis
Direct examination of smears stained with
fourescein conjugated monoclonal or polyclonal antibodies
should be incubated in a humid environment at 350C without CO2
Bordetella pertussis
slow grower; should be held for 7 to 12 days
Bordetella pertussis
Bordetella pertussis
Culture Media:
i. Regan – Lowe
ii. Bordet – Gengou
Composed of: Potato
20 – 30 % blood
Glycerol
- Small round and shiny
- may give the appearance of
“drop of mercury”
Bordetella pertussis
