Haemophilus Influenzae By: Ebony C. Petersen

Goal The goal of this presentation is to gain fundamental knowledge on Haemophilus influenzae and to increase awareness of the clinical features, symptoms, and diagnostic methods associated with the disease.

Objectives After the presentation, the learner(s) will be able to: Project the characteristics and growth requirements. Identify the causative agent of H. influenzae disease. Assess the different route(s) of transmission. Recall the clinical features of H. influenzae infection. Differentiate the different symptoms associated with each type of infection. Generate methods use to aid in the diagnosis. Evaluate possible risk factors and complications. Propose effective treatment and preventative measures.

History /Introduction The genus Haemophilus contains many species, but H. influenzae is the most common pathogen. It was first described by Pfeiffer in 1892 during an outbreak of influenzae. ("Pfeiffer's bacillus"). During this time, the organism was thought to be the causative agent of the flu. The organism was then given the name Haemophilus by Winslow, et. al in In 1933 Smith, et al. established that influenzae was caused by a virus and the H. influenzae was a cause of secondary bacterial infections.

Characteristics Pleomorphic (tiny) Gram negative rod Non motile Non spore forming Fastidious Generally aerobic Requires both X and V factors Capnophilic (CO 2 ) Encapsulated vs. Non-encapsulated Outermost structure (polysaccharide capsule)

Etiologic Agent Disease is caused by the bacterium H. influenzae. Six identifiable serotypes of H. influenzae (a-f) Other strains are non identifiable types (HiNT) 95% of invasive infections caused by type b (Hib) Retrieved from:

Routes of Transmission Humans are the only known reservoir. Non encapsulated strain is present in about 75% of healthy people. Principal (main) habitat is the nasopharynx. Disease is usually caused by encapsulated strains that penetrate the epithelium of the upper respiratory tract. Due to its invasive nature, organism can enter circulation. Primary mode of transmission is via respiratory droplets (coughing, sneezing) or direct person-to-person contact. Retrieved from

Clinical Features Haemophilus influenzae can affect many organs and cause many different types of infections. Type B (Hib) causes: Meningitis (brain) Epiglottitis (windpipe) Pneumonia (lung) Arthritis (joint) Cellulitis (skin) Osteomyelitis (bone) Bacteremia (blood) (*Pre vaccination era) Non type-able causes: Otitis media Bronchitis/ Sinusitis

Common Symptoms Three most common symptoms : 1. Pneumonia - Fever, Chills, Chest pain - Cough, Difficulty breathing 2. Bacteremia - Fever, Chills, Abdominal pain - Vomiting, Diarrhea, Nausea 3. Meningitis - Fever, Headache, Stiff Neck - Altered mental status, Confusion, Fatigue **Note: Common cause of ear infections in children and bronchitis in adults.

Diagnostic Methods Culture 1. Specimens of choice: - CSF - sputum - joint fluid - pleural fluid - middle ear aspirates 2. Media: - Chocolate Agar Plate - Blood Culture 3. Conditions: °C, - ~ 5% CO 2, hrs 4. Colony Morphology: - "water droplets"

Diagnostic Methods (Cont’d) Gram Stain 1. Pink, pleomorphic, G- Biochemical Reactions 1. Oxidase + 2. Catalase +

Diagnostic Methods (Cont’d) Growth Factor Requirements 1.X/V strips 2. Quad Plate H. influenzae will only grow H. influenzae will only grow around the disk containing in the quadrant containing Hemin (X) and NAD (V). Hemin + NAD & quadrant containing 5% horse blood, but will not hemolyze it.

Diagnostic Methods (Cont’d) Satellitism on BAP (Streaked with known Staph. Aureus) Serological Typing (Slide Agglutination)

Additional Methods Porphyrin test RapID NH (4 hr Biochemical) Immunoflourescence (IFE) Counterimmunoelectrophoresis Real time PCR

Risk Factors Population most at risk: - Infants and children (5 years old & younger) - Elderly (65 years old and older) People with certain medical conditions: - Sickle cell disease - Asplenia (no spleen) - HIV infection - Malignant neoplasms (tumor) - Antibody/Complement deficiency syndromes

Prognosis Overall, the complications differ based on the type of infection. Most strains of H. influenzae, (including Hib) colonize a person's nasopharynx without causing disease. Meningitis can cause brain damage or hearing loss. Bacteremia can result in a loss of limb(s). Timely treatment may prevent coma and death.

Treatment Drugs of Choice: - Ampicillin - Chloramphenicol - 3rd generation Cephalosporin Example: Ceftriaxone or Cefotaxime Treatment course is usually 10 days. Many isolates of H. influenza can produce Beta-lactamase. Ampicillin resistant strains of Hib are now common throughout US. In most medical centers, 25-30% of Hib are now resistant to penicillin and ampicillin. In some medical centers, 50-60% of Hib isolates are ampicillin resistant. If Beta lactamase positive, Ceftriaxone becomes the drug of choice.

Prevention Hib vaccine is recommended for all children younger than 5 years of age in the US. Vaccination can prevent H. influenzae type b (Hib), but not the other types ("strains"). Hib vaccine can prevent meningitis, epiglottitis, and other infections cause by Hib bacteria. Hib vaccine is usually given to infants starting at 2 months of age. admits-flu-vaccines-dont-work/

References Agrawal, A., & Murphy, T. (2011). Haemophilus influenzae infections in the H. influenzae Type b conjugate vaccine era. Journal of Clinical Microbiology, 49(11), American Society for Microbiology (2011). Haemophilus influenzae Retrieved from associated-figure-resource/1953-haemophilus- influenzae-enlarged-view. Center for Disease Control and Prevention (2012). About Haemophilus influenzae Disease. Retrieved from Center for Disease Control and Prevention (2012). Haemophilus influenzae type b. Retrieved from Center for Disease Control and Prevention. (2012). Chapter 9: Identification and Characterization of Haemophilus influenzae. Retrieved from characterization-hi.htmL Estridge, B., & Reynolds, A. (2012). Basic Clinical Laboratory techniques. 6th edition. New York: Delmar-Cengage Learning. Mahon, C., Lehman, D., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology. 4th edition. Missouri: W.B. Saunders Company. Thigpen, M.C., Whitney C.G., Messonnier N.E., et. al. (2011). Bacterial Meningitis in the United States New England Journal of Medicine, 364(21),

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