HAEMOPHILU S HISTORY Hib was found in a

HAEMOPHILU S

HISTORY Hib was found in a group of patients during an influenza outbreak in 1892 Haemophilus influenzae was first isolated in 1890 by Richard Pfeiffer

MEDICALLY IMPORTANT SPP q q q H. Influenzae H. ducreyi H. haemolyticus. H. phrophilus H. segnis q q q H. aegyptius (Koch. Weeks) H. Para Influenzae H. parahaemalyticus H. aphrophilus

HAEMOPHILUS INFLUENZAE Misnamed – originally thought to cause the “flu” Now know that flu is caused by viruses In some cases of flu, H. influenzae is secondary infection

MORPHOLOGY Haemophilus influenzae is : v a pleomorphic gram-negative coccobacillus. v H. influenzae may be either encapsulated (typeable) or unencapsulated (nontypeable). v There are six encapsulated serotypes (designated a–f) that have distinct capsular polysaccharides.

MICROSCOPY Gram Stain Morphology Usually very small pleomorphic gram negative coccobacilli or bacilli

Direct smear of H. influenzae in CSF in a case of meningitis. Note the TINY intracellular and extracellular pleomorphic gram-negative bacilli.

GENERAL PROPERTIES v v Extracellular pathogen, does not invade into cells Fastidious v. Lots of growth factors v. Haemophilus = blood loving v. However, this organism can not grow on blood agar alone! v. Requires X factor (hematin) v. Requires V factors (NAD)

Haemophilus species require growth factors: X-factor ( hemin) Heat-stable substance Present in RBC and released with degradation of hemoglobin V-factor (NAD: Nicotinamide adenine dinucleotide) Heat- labile Found in blood or secreted by certain organisms

X AND V FACTOR: X factor is used by H. influenzae to produce essential respiratory enzyme such as cytochrome – catalase and peroxidase. V Factor is used as electron carriers in the organism oxidation reduction system

CULTURE: Chocolate Blood agar + CO 2 Agar + CO 2 Colony Morphology No growth on BAP or MAC On CA: semi-opaque, gray-white, convex, mucoid.

BLOOD AGAR CHOCOLATE AGAR

HAEMOPHILUS SPECIES: IDENTIFICATION Gram stain Gram negative cocco-bacillus Catalase + Oxidase + X and V factor strips or disks

Species Growth Factor Required -----------------------------H. influenzae X+V H. parainfluenzae V H. ophrophilus X H. ducreyi X ------------------------------

SATELLITISM Satellitism test when we streak S. aureus (produce V factor) across the surface of on inoculated blood agar plate. The colonies are largest nearest to the S. aureus column of growth than those farthest from it.

SATELLITISM

H. INFLUENZAE TYPING H. influenzae can be divided into eight biotypes on the basis of three biochemical test (indole production – urease activity and Ornithine Decarboxylase) The majority clinical isolate are typed based on capsular polysaccharide into three biotypes (I, III). Invasive type b strains are of biotype I.

VIRULENCE FACTORS Capsule Antiphagocytic Ig. A Protease Cleaves Ig. A on mucosal surfaces Lipid A Effects ciliated respiratory epithelium Pili Attachment

VIRULENCE FACTORS v. Endotoxin which is part of all Gramnegative cells v. Helps respiratory tract colonization by blocking cilia clearance v. Induces inflammation at site of infection

TRANSMISSION: Transmission occurs through direct contact with respiratory droplets from nasopharyngeal carrier or case patient. Neonates can acquire infection by aspiration of amniotic fluid or contact with genital tract secretions containing the bacteria.

CLINICAL INFECTIONS: TYPEABLE STRAINS Acute epiglotitis or laryngotracheal infection in small children Can cause airway obstruction needing immediate tracheostomy Cellulitis/arthritis cheek and upper extremities

CLINICAL INFECTIONS: TYPEABLE STRAINS Meningitis Children under 6 years Contagious, vaccine has decreased incidence Pneumonia/septicemia In children Conjunctivitis “pink eye” very contagious

CLINICAL INFECTIONS: NONTYPEABLE STRAINS Otitis media Children 6 months- 2 years Sinusitis Pneumonia, bronchitis In adults These sites are all in proximity to respiratory tract

LABORATORY DIAGNOSIS CSF (Never Refrigerate) SPUTUM BLOOD CULTURE

CULTURING AND ISOLATION Can be grown on Blood agar and Chocolate agar Need 5 – 10 % carbon dioxide A streak of Staphylococcus should be streaked across the plate at 370 c Opaque colonies appear shows as Satellitisim Iridescence Demonstrates on Levinthal’s medium

SEROLOGY IN CSF Coagglutination – Latex agglutination Counter current immuno- electrophoresis (CIE)

VACCINE three monovalent conjugate Hib vaccines and three combination vaccines that contain Hib conjugate are available. An infant primary series (2, 4, and 6 months of age or 2 and 4 months of age, depending on the vaccine type used) and a booster dose at 12 through 15 months of age is recommended

HAEMOPHILUS AEGYPTICUS (KOCH – WEEKS BACILLUS) It grows more slowly than H. influenzae It requires X and V factor. Causes highly contagious conjunctivitis (Pink Eye) and Brazilian Purpuric Fever

HAEMOPHILUS DUCREYI Causative agent of chancroid or soft chancre (STD), highly contagious Specimens should be collected from base of lesion, inoculated directly to enriched media and held for 5 days Gram stain appears as groups of coccbacilli that resemble a ‘school of fish” or “railroad tracks” Requires only X factor to grow

HACEK GROUP HACEK o is an acronym of the first initial of each genus that belong in the group: Haemophilus aphrophilus: Actinobacillus actinomycetemcomitans Cardiobacterium hominis Eikenella corrodens Kingella species Habitat o Commensals of oral cavity

HACEK GROUP: Gram-negative bacilli Require an increased CO 2 (5%-10%) environment Slow/poor growers Usual flora of the Oropharyngeal area Opportunists in immunocompromised hosts Clinical Significance Infective endocarditis Periodontal disease Dental caries Infections following dental procedures