Haemophilus Exam 2 Flashcards
What organism is small, non-motile, pleomorphic gnb, capnophilic, and mousy odor.
Haemophilus spp.
What factors does Haemophilus spp. require?
X factor (protoporphyrin IX) and V factor (nicotinamide adenine dinucleotide-NAD)
True/false? Haemophilus spp. are prone to drying and sensitive to temperature, thus need to be inoculated to chocolate immediately or use T-1 medium (which supports N. meningitidis, H. influenzae, and S. pneumoniae.
True.
How does H. ducreyi (STI) need to be handled?
Ulcer needs to be cleaned. Cotton swab with saline is used to collect bacteria from ulcer.
Why does Haemophilus spp. not grow well on SBAP?
SBAP only contains X factor
What agar should be used for children with CF?
Chocolate agar with bacitracin. It isolates H. influenzae and prevents overgrowth of many G+ and G- cocci.
What organism can Haemophilus spp. can grow near on SBAP? What is this phenomenon called?
Staph aureus; releases X factor and produces V factor.
Satellite phenomenon
Which Haemophilus specie is not normal flora?
H. ducreyi
What is the most common type infection?
Type B; can cause meningitis, bacteremia, epiglottis
Why are most infections of H. influenzae caused by non-typeable strains?
Because of vaccines
ID for Haemophilus spp?
Large, round, colorless to gray colonies on chocolate. Oxidase positive (purple)
When are the 4 does for H. influenzae vaccine given?
1st dose-2 months of age
2nd dose-4 months of age
3rd dose- 6 months
4th dose- 12-15 months of age
What does H. ducreyi look like what on gram stain?
A school of fish (arrows)
What is H. ducreyi usually confused with?
Syphilis
Why is it important to differentiate H. ducreyi from syphilis?
They have different treatments. Syphilis is treated with penicillin and H. ducreyi is treated with macrolides.
Describe Legionella pneumophila
Obligate aerobe
Gram neg bacilli
Motile
What does Legionella pneumophila utilize?
Utilizes protein not carbs for growth
True/false? Legionella pneumophila is transmitted from person to person.
False. Is not
How is Legionella pneumophila transmitted?
Inhalation of mist containing microbes.
What can Legionellosis cause?
Legionnaires disease- causes pneumonia.
Pontiac fever-flu-like symptoms; less severe and doesn’t present with respiratory involvement.
How does Legionella pneumophila evade host defenses?
Is taken up by macrophages but NOT killed. Microbe replicates and kills macrophage and infects new cells. They evade destruction by studded with host factors. They also release chemicals that degrade host lipases and proteinases.
What is Legionella pneumophila treated with?
Fluoroquinolones and macrolides
Penicillin, cephalosporins, and aminoglycosides are ineffective.
What is the media of choice for Legionella pneumophila?
Buffered Charcoal Yeast Extract; one with cysteine and one without. Sent to reference labs.
What is the presumptive ID for Legionella pneumophila? Definitive ID?
Fluoresce a yellow-green on BCYE under UV light source. Definitive ID comes via serotyping.
What is the Bordetella spp. vaccine called? What is the booster called?
DTaP-infants and toddlers (5 doses)
Tdap- preteens and teens
What Bordetella species is also known as whooping cough?
Bordetella pertussis
Bordetella pertussis/parapertussis ID?
Both motile, gram - coccobacilli to short rods.
Infect only humans, pathogens.
Cause upper respiratory tract infections.
Spread from person to person via respiratory droplet.
Cause of kennel cough in dogs
Bordetella bronchiseptica
What are the virulence factors of Bordetella pertussis?
Fimbriae-connect to the epithelium URT
Toxins- pertussis toxin that impairs function of macrophages and neutrophils.
Outer bacterial membrane- help protect against lysoenzymes.
True/false? If antibiotics are given late (paroxysms have started) they are unlikely to alter the disease progression.
True.
List and describe the stages of Whooping Cough.
Catarrhal- mild cough and cold; usually lasts 7-10 days, up to 21 days.
Paroxysmal- Increase in severe coughing up to 25x/day. May last 1-6 weeks; up to 10 weeks.
Convalescent- usually 7-10 days, recovery, less persistent cough which disappears in 2-3 weeks.
When are people infectious with Whooping Cough?
Catarrhal stage through the 3rd week of Paroxysms.
What are acceptable specimens for Bordetella spp? Unacceptable?
Acceptable: Nasopharyngeal aspirate, Nasopharyngeal swab (Dacron or calcium alginate swabs preferred).
Unacceptable: Sputum, throat, or nares swab (These areas lack ciliated epithelium which is where the bacteria bind to via fimbriae.
What is the selective media for Bordetella spp?
Bordet-Gengou, Modified Jones-Kendrick charcoal agar, Regan-Lowe (gold standard-ID)- Confirm with PCR and serology
What do the colonies of Bordetella pertussis and parapertussis?
Small, shiny colonies resemble MERCURY DROPLETS
What is the treatment for B. pertussis?
Susceptible to macrolides: erythromycin, azithromycin, and clarithromycin. **In infants less than a month old azithromycin is preferred as erythromycin as been linked to infantile hypertrophic pyloric stenosis.
