HAEMOPHILUS Haemophilus influenzae Haemophilus ducreyi Haemophilus influenzae Pfeiffers
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HAEMOPHILUS
Haemophilus influenzae, Haemophilus ducreyi Haemophilus influenzae: ◦ Pfeiffer’s bacillus; influenza bacillus – 1892 ◦ Meningitis, pneumonia, epiglottis, bronchitis, otitis media, septic arthritis H. ducreyi - Chancroid
Haemophilus influenzae Aerobic gram-negative pleomorphic bacteria Polysaccharide capsule Six different serotypes (a-f) of polysaccharide capsule 95% of invasive disease caused by type b (Hib) Type b – polyribosyl ribitol phosphate OMP antigens – 13 types Smooth to rough variation
Microscopy EM Gram stain
H. influenzae type b -Epidemiology Reservoir Asymptomatic human carriers Transmission Respiratory droplets Temporal pattern Peaks in Sept-Dec & March-May
Risk Factors for Invasive Disease � Exposure factors ◦ household crowding ◦ child care centers ◦ low socioeconomic status ◦ low parental education ◦ school-aged siblings � Host factors ◦ race/ethnicity ◦ chronic disease
Clinical Presentation Meningitis: (Pre-vaccine era) ◦ Leading cause of bacterial meningitis and other invasive bacterial disease - children <5 years. ◦ Two-thirds of cases were among children <18 months. ◦ Approximately one in 200 children developed invasive Hib disease before the age of 5 years. Epiglottis: Pneumonia: Septic Arthritis:
Haemophilus Influenzae Mode of Transmission: Droplet infection and discharge from the upper respiratory tract during the infectious period. Incubation Period Unknown, probably short, 2 -4 days. Infectious Period - As long as the organism is present, even in the absence of nasal discharge. - Noninfectious within 24 to 48 hours after the start of effective antibiotics.
Case Definition Clinical case definition Invasive disease caused by H. influenzae can produce any of several clinical syndromes, including meningitis, bacteremia, epiglottitis, or pneumonia. Laboratory criteria for diagnosis Isolation of H. influenzae from a normally sterile site (e. g. , blood or cerebrospinal fluid [CSF] or, less commonly, joint, pleural, or pericardial fluid).
Lab diagnosis Specimens – CSF, Blood, Throat swab, Sputum, Pus, aspirates Transport – sensitive to low temperature Gram stain – Pleomorphic GNB Culture – Blood agar, Chocolate agar X & V factors, 5 -10% CO 2
X factor - heat stable Protoporphyrin IX ◦ Required for synthesis of Catalase & cytochrome C oxidase V factor – heat labile; NAD / NAD phosphate, H 2 acceptor in cell metabolism, present within RBC
Culture X V Staph streak Colonies on chocolate agar Hemophilus colonies Colonies on human blood agar
X – V factors (Accessory growth factors) Growth
SATELLITISM Release of V factor from RBC in blood agar for better isolation of H. influenzae First, suspected specimen (or colonies of) containing H. influenzae is streaked on blood agar. Next, β-haemolysin producing Staph. aureus is streaked perpendicularly on same blood agar plate.
Satellitism Large and well-developed alongside the streak of staphylococcus and smaller farther away smaller large and well-developed
Incubate at 37 o. C for 18 -24 hrs If H. influenzae is present in specimen, the colonies will be larger near to Staphylococcus. aureus growth V factor is available at high concentration near Staphylococcal growth.
Biochemical reactions: ◦ Catalase & oxidase +ve ◦ Glucose fermented ◦ Nitrates reduced to nitrites ◦ 8 biotypes based on indole, urease & ornithine decarboxylation
Serodiagnosis: ◦ Quellung reaction ◦ Capsular Antigen detection in CSF, Urine & Pus. ◦ Immunofluorscence
H. influenzae type b Polysaccharide Vaccine Not effective in children younger than 18 months of age Two conjugate vaccines licensed Use different carrier proteins
Conjugate Hib vaccine PRP-T PRP-OMP • • • PRP is polyriosyl-ribitol phosphate T-Tetanus OMP-outer membrane protein of N. meningitidis
Vaccine schedule Vaccine PRP-T PRP-OMP 2 mo 4 mo x x 6 mo 12 -18 mo x x x • Number of doses child requires depends on current age • Children 15 -59 mnths - 1 dose • Combination vaccines
Hemophilus ducreyi � Chancroid � GNCB, – STD bipolar staining, School of fish appearance � Requires � Rabbit only X factor blood agar / Chocolate agar + 1% iso vitalex + vancomycin � 10% � CAM CO 2 & high humidity of chick embryo
Chancroid / soft sore � Tender, non-indurated, irregular ulcers over genitalia. � Venereal � Enlarged disease inguinal lymph nodes; inguinal abscess. � Hypersensitivity � Co-trimoxazole, reaction erythromycin
Bubo