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

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

3. 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.

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

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

6. Epidemiology Adults (> 15 years)
S. pneumo %
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

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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

13. Meningitis Pathogens
L. monocytogenes

14. 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.

15. Listeria umbrella motility at RT

16. 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 +

17. Esculin hydrolysis
Catalase; bubbles production
Typical Listeria rxn

18. Listeria on BA

19. 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

20. Listeria pathogenesis

21. 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.

22. 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.

23. Streptococcus pneumoniae

24. 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)

25. 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

26. 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

27. 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

28. 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

29. Laboratory diagnosis of S. pneumoniae

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

31. Optochin

32. Bile solubility

33. Quellung reaction

34. 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.

35. 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

36. 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

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

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

39. 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

40. Oxidase test
TSIA

41. API 20 E

42. API 20 E Flash
Thank you