Lecture 2 Epidemiology of meninigitis Dr. Abdelraouf A. Elmanama Islamic University-Gaza Medical Technology Department

Lecture outlines Epidemiology of menigitis Risk factors of meningitis Pathogens details Vaccines Prophylactics Introduction to Lab diagnosis

Epidemiology Incidence is between 3-5 per 100,000 More than 2,000 deaths annually in the U.S. Relative frequency of bacterial species varies with age.

Epidemiology Neonates (< 1 Month) Gm (-) bacilli 50-60% Grp B Strep 20-40% Listeria sp. 2-10% H. influenza 0-3% S. pneumo 0-5%

Epidemiology Children (1 month to 15 years) H. influenzae 40-60% Declining dramatically in many geographic regions N. meningitidis 25-40% S. pneumo 10-20% The decline is mainly due to the use of conjugated vaccins

Epidemiology Adults (> 15 years) S. pneumo 30-50% N. Meningitidis 10-35% Major cause in epidemics Gm (-) Bacilli 1-10% Elderly S. aureus 5-15% H. influenzae 1-3% >60 include Listeria, E. coli, Pseudomonas

Risk factors Age. Most cases of viral meningitis occur in children younger than age 5. In the past, bacterial meningitis also usually affected young children. But since the mid-1980s, as a result of the protection offered by current childhood vaccines, the median age at which bacterial meningitis is diagnosed has shifted from 15 months to 25 years.

Risk factors Living in a community setting. College students living in dormitories, personnel on military bases, and children in boarding schools and child care facilities are at increased risk of meningococcal meningitis, probably because infectious diseases tend to spread quickly wherever large groups of people congregate.

Risk factors Pregnancy. If you're pregnant, you're at increased of contracting listeriosis — an infection caused by listeria bacteria, which may also cause meningitis. If you have listeriosis, your unborn baby is at risk, too.

Risk factors Working with animals. People who work with domestic animals, including dairy farmers and ranchers, have a higher risk of contracting listeria, which can lead to meningitis.

Risk factors Compromised immune system. Factors that may compromise your immune system — including AIDS, diabetes and use of immunosuppressant drugs — also make you more susceptible to meningitis. Removal of your spleen, an important part of your immune system, also may increase your risk.

Risk factors Alcoholism Autoimmune disorders (e.g., lupus( Immunosuppressive drugs (e.g., corticosteroids, chemotherapies( Intravenous drug abuse cancer, diabetes Smoking Head injuries and brain surgery also put patients at risk for meningitis

Meningitis Pathogens L. monocytogenes

Morphology and general characteristics Small G+ B which may appear pleomorphic Nonsporing and nonencapsulated Motile by peritrichous flagella at RT (umbrella motility) and polar flagella at 370 C.

Listeria umbrella motility at RT

L. monocytogenes Biochemistry Grows well on ordinary lab media and on CBA it produces beta hemolysis and colonies resemble Strep. pyogenes colonies Aerobic to microaerophilic Biochemistry Catalase + TSI= A/A, H2S- Esculin hydrolysis +

Esculin hydrolysis Catalase; bubbles production Typical Listeria rxn

Listeria on BA

Antigenic structure CAMP + Grows in 6.5% NaCl Four major serogroups (1-4) based on O antigen Serotypes based on H antigen Type 1b accounts for most infections; May also find 1a and 4b in significant amounts

Listeria pathogenesis

Listeria pathogenesis Pregnancy renders an individual more susceptible to the infection, though the effect on the mom is usually minimal. It can be devastating for the fetus or newborn. In neonates, the disease occurs in two forms Early onset – the infant is infected transplacentally with the production of septicemia and granulomatous foci in many organs. This may result in abortion, stillbirth, premature delivery, or death soon after birth. The baby is born with cardio and respiratory distress, vomiting, diarrhea, meningitis, hepatosplenomegaly, and skin lesions. The fatality rate is 70-90% in untreated cases.

Listeria pathogenesis Late onset – the infant is infected from the genital tract during delivery. Infection usually begins 1-4 weeks after birth and is manifested as meningitis with a high fatality rate. Antimicrobic susceptibility/treatment Prognosis is poor in neonates so infected moms should be treated as soon as disease is diagnosed Penicillin is the drug of choice. Can also use erhthromycin or tetracycline.

Streptococcus pneumoniae

Morphology and general characteristics Gram-positive cocci – lancet / bullet shape Diplococci (arranged in pairs) – the adjacent ends of pair are rounded while other ends are pointed Virulent strains are capsulated CULTURAL CHARACTERISTICS Facultative anaerobic; 5-10% CO2 enhance growth Grow on enriched media (blood & chocolate agar)

PATHOGENICITY FACTORS Capsule Antiphagocytic S. pneumoniae > 80 serotypes on the basis of antigenic differences in polysaccharide capsule Toxins and extracellular enzymes IgA protease : help in colonization in resp tract Pneumolysin - properties like Streptolysin Neuroaminidase – spreading factor

10-30% of normal people carry one or more serotypes in throat Pneumococcal pneumonia High grade fever, cough, rusty sputum (reddish) Difficult breathing, chest pain Meningitis (all age groups) Sinusitis Otitis media

Penicillins – drugs of choice PREVENTION TREATMENT Penicillins – drugs of choice Penicillin-resistant strains are treated with erythromycin PREVENTION Vaccination with polyvalent vaccine prepared from polysaccharide capsules of 23 serotypes Given to susceptible groups – elderly patients, diabetics, chronic pulmonary disease, immunocompromised

Susceptibility  Children< 2, adults over 65, Splenectomy, Chronic lymphatic leukemia, Multiple myeloma, Sickle cell anemia, Postinfluenza, COPD, smokers  Clinical Features Rusty sputum Single shaking chill    Associated Sites of Infection Bacteremia 25-50% Pleural effusions, arthritis, meningitis, endocarditis Sinusitis    Sputum Gram Stain   Encapsulated lancet-shaped Gram-positive diplococci or short chains

Laboratory diagnosis of S. pneumoniae

CULTURAL CHARACTERISTICS Facultative anaerobic; 5-10% CO2 enhance growth Grow on enriched media (blood & chocolate agar) Alpha-haemolytic colonies on blood agar

Optochin

Bile solubility

Quellung reaction

TREATMENT Penicillins – drugs of choice Penicillin-resistant strains have been reported due to alteration in PBP Penicillin-resistant strains are treated with erythromycin PREVENTION Vaccination with polyvalent vaccine prepared from polysaccharide capsules of 23 serotypes. Given to susceptible groups – elderly patients, diabetics, chronic pulmonary disease, immunocompromised.

HAEMOPHILUS IMPORTANT SPECIES H. influenzae H. ducreyi Gram-negative coccobacilli Some strains capsulated Six serotypes (a-f) on the basis of capsular antigens Type b (Hib)- the main pathogen Non-capsulated strains are present in nasopharynx of 25-80% of healthy people Hib in 2-5% of healthy people

Haemophilus influenzae Growth Requirements Growth improved in CO2 Grow on enriched media (chocolate agar) Needs X factor (haematin) & V factor Nicotinamide Adenine Dinuclotide (NAD) Both are present in RBCs and are released on heating (chocolate agar) V- factor can be produced by yeast & S. aureus H. influenzae can grow on blood agar in vicinity of colony of S. aureus - satellitism

SATELLITISM BY H. INFLUENZAE colonies S. aureus Blood agar plate

PATHOGENESIS Type b (capsulated) Is primary pathogen IgA protease - degrades secretory IgA and help attachment to respiratory mucosa Capsule - antiphagocytic Endotoxins

Gram negative bacilli Enterobacteriacae and Others MacConkey agar is good for almost all gram negative (there are few exceptions) Oxidase test for preliminary differentiation TSIA for initial identification API 20 E is for species identification

Oxidase test TSIA

API 20 E

API 20 E Flash Thank you