Haemophilus Infections and Conjunctivitis

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Questions and Answers

What is the main difference between Haemophilus influenzae biogroup aegyptius and Haemophilus influenzae?

One is a strict human pathogen, while the other is not

One causes Brazillian purpuric fever, while the other causes meningitis

One causes conjunctivitis in pediatric patients, while the other causes systemic disease (correct)

One is encapsulated, while the other is nonencapsulated

What is a characteristic of Haemophilus ducreyi?

It is a strict human pathogen (correct)

It is a common inhabitant of the human microbiota

It causes pink eye

It is the causative agent of syphilis

What is the primary site of infection for Haemophilus parainfluenzae?

Lung tissue

Mitral valve (correct)

Brain tissue

Skin lesions

What is the difference between Haemophilus influenzae and Haemophilus aegyptius?

One causes systemic disease, while the other causes localized infection Signup and view all the answers

What is the name of the disease caused by Haemophilus influenzae biogroup aegyptius?

Brazillian purpuric fever Signup and view all the answers

What is the requirement for Haemophilus spp. growth?

Both X-Factor and V-Factor Signup and view all the answers

What is the characteristic odor of Haemophilus influenzae colonies?

mousy or bleach-like Signup and view all the answers

Which of the following bacteria is responsible for endocarditis and resides in human oral mucosa?

Haemophilus spp. Signup and view all the answers

What is the primary difference between Haemophilus parainfluenzae and Haemophilus influenzae colonies?

moisture level Signup and view all the answers

What is the characteristic of Haemophilus spp. in terms of motility?

Non-motile Signup and view all the answers

What is the derivation of the name 'Haemophilus'?

From the Greek word meaning 'blood-lover' Signup and view all the answers

What is the purpose of the porphyrin test in Haemophilus species identification?

to identify X factor-requiring species Signup and view all the answers

Which of the following bacteria is NOT part of the HACEK group?

Moraxella spp. Signup and view all the answers

What is the characteristic appearance of Haemophilus ducreyi colonies?

small, flat, smooth, and transparent to opaque Signup and view all the answers

How are Haemophilus ducreyi cells arranged under microscopic examination?

singly or in groups Signup and view all the answers

What is the byproduct of Staphylococcus aureus, Streptococcus pneumoniae, or Neisseria spp. that helps in the recognition of Haemophilus spp.?

V-Factor Signup and view all the answers

What is the specific growth requirement for Haemophilus ducreyi?

33°C only Signup and view all the answers

Study Notes

Haemophilus spp. and Other Fastidious Gram-Negative Bacilli

Satellitism

Phenomenon where Haemophilus spp. require V factor
Occurs when Staphylococcus aureus, Streptococcus pneumoniae, or Neisseria spp. produce V factor
Organisms: source of V factor
BAP: source of X factor

Pasteurellaceae Characteristics

Genera: Haemophilus, Actinobacillus, Pasteurella, and Aggregatibacter
Gram-negative, pleomorphic, coccoid to rod-shaped cells
Generally bacilli
Nonmotile and facultative anaerobic
Catalase and nitrate to nitrite reduction (+)
Oxidase negative (-)

HACEK

Reside in human oral mucosa
Causes endocarditis
Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella

Haemophilus spp. Characteristics

Derived from Greek word meaning "blood-lover"
Require X factor (hemin or hematin) and V factor (nicotinamide adenine dinucleotide)
BAP (Blood Agar Plate) for V factor dependent Haemophilus spp.

Adherence Mechanisms

NTHi strains: adherent to human epithelial cells, localized infection
Serotype B: not adherent to human epithelial cells, systemic infections

Infections

Haemophilus aegyptius: acute conjunctivitis (Koch-Weeks bacillus), "pink eye"
Haemophilus influenzae biogroup aegyptius: conjunctivitis in pediatric patients, nonencapsulated, causes systemic disease known as Brazillian purpuric fever (BPF)
Haemophilus ducreyi: strict human pathogen, smallest pathogenic bacteria, causative agent of chancroid (highly communicable ST genital ulcer disease)
Haemophilus parainfluenzae: endocarditis, mitral valve as primary site of infection

Laboratory Diagnosis

Haemophilus ducreyi and Haemophilus aegyptius: CAP with 1% IsoVitaleX or Vitox (source of X and V factor)
Haemophilus ducreyi: grows best at 33°C, Nairobi biplate, GC agar base with 2% bovine hemoglobin and 5% fetal calf serum with vancomycin, Mueller Hinton agar with 5% chocolatized horse blood with vancomycin

Macroscopic Examination

Haemophilus influenzae: translucent, tannish, moist colonies with a distinct "mousy" or bleach-like odor
Haemophilus parainfluenzae: tannish and drier with a medium to large size compared with Haemophilus influenzae
Haemophilus haemolyticus and Haemophilus parahaemolyticus: β-hemolytic on BAP
Haemophilus ducreyi: small, flat, smooth, nonmucoid, transparent to opaque colonies, "clumpy" nonhemogeneous appearance when suspended in saline

Microscopic Examination

Small, gram-negative coccobacilli to long filaments
Haemophilus ducreyi: pale staining gram-negative coccobacilli arranged singly or in groups, "school of fish" or "railroad tacks" or "fingerprints"

Biochemical Tests

Porphyrin Test: alternative method for differentiating the hemeproducing species of Haemophilus
Principle: based on the ability of the organism to convert the substrate δ-aminolevulinic acid (ALA) into porphyrins or porphobilinogen
Reagent: p-dimethylaminobenzaldehyde (Kovacs' reagent)
Result: red color in lower aqueous phase (presence of phosphobilinogen), reddish orange fluorescence in UVL detection at 360 nm (presence of porphyrins)

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Description

This quiz covers the basics of Haemophilus infections, including adherence mechanisms, types of infections, and specific strains such as NTHi and Haemophilus influenzae biogroup aegyptius. It also touches on conjunctivitis and its causes.