1. Remya Bacterial meningitis @Remya

2. Remya Learning objectives The objective of the lecture is to discuss: the aetiological agents implicated in bacterial meningitis methods of processing the CSF sample in microbiology lab to diagnose the bacterial agent of meningitis immunoprophylaxis of meningitis prevalence of antibiotic resistance of bacteria causing meningitis.

3. Remya Learning Outcomes At the end of the lecture, students should be able to: List the aetiological agents implicated in bacterial meningitis. Describe mechanisms involved in pathogenesis of bacterial meningitis. Describe the techniques of processing the CSF sample in microbiology lab and diagnosing the bacterial agents of meningitis. Discuss the immunoprophylaxis of meningitis. Discuss the prevalence of antibiotic resistance of bacteria causing meningitis.

4. Remya The disease caused by the inflammation of the meninges (protective membranes covering the brain and spinal cord). Usually caused by an infection of the fluid surrounding the brain and spinal cord. Meningitis is also referred to as spinal meningitis. Usually bacteria or viruses But can also be caused by physical injury, cancer or certain drugs.

5. Remya Knowing the specific cause of meningitis is very important. The severity of illness and the treatment for meningitis differ depending on the cause. Bacterial meningitis is usually more severe than viral, fungal, or parasitic meningitis. But it can be treated with antibiotics that can prevent severe illness and reduce the spread of infection from person to person.

6. Remya Causes Mostly caused by bacteria, viruses, parasites, and fungi. Infects the blood and the CSF. Also develop from non-infectious causes including certain diseases like AIDS, cancer, diabetes, physical injury or certain drugs that weaken the body’s immune system. Bacterial Meningitis Bacterial meningitis is usually more severe than viral meningitis. Bacterial meningitis can have serious after-effects such as brain damage, hearing loss, learning disabilities etc.

7. Remya Risk Factors of Bacterial Meningitis Age  Infants are at higher risk for bacterial meningitis than people in other age groups. Community setting.  College students living in dormitories, military personnel and children in childcare facilities are at an increased risk for meningococcal meningitis. Certain medical conditions  There are certain diseases, medications, and surgical procedures that may weaken the immune system or increase risk of meningitis in other ways.

8. Remya Working with meningitis-causing pathogens  Microbiologists who are routinely exposed to meningitis-causing pathogens are at increased risk. Pregnancy.  Pregnant women are at an increased risk of catching listeriosis. The fetus is also at risk. Working with animals.  Dairy farmers, ranchers and other people who work with domestic animals are at an increased risk of contracting listeriosis.

9. Remya Causes of bacterial meningitis also vary by age group Age Group Neonates Children/ Young adults Adult Miscellaneous Causes Group B Streptococci, Escherichia coli, Listeria monocytogenes Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae N. meningitidis, S. pneumoniae Mycobacteria

10. Remya Transmission Contagious. Exchange of respiratory and throat secretions. Listeria monocytogenes by eating contaminated food. People in the same household or daycare center or anyone with direct contact with a patient's oral secretions - increased risk of getting the infection. Should receive antibiotics to prevent them from getting the disease. Close or prolonged contact with a patient with meningitis caused by N. meningitidis or H. influenzae serotype b.

11. Remya Signs & Symptoms Meningitis infection is characterized by a sudden onset of fever, headache, and stiff neck. It is often accompanied by other symptoms, such as: Nausea Vomiting Photophobia (sensitivity to light) Altered mental status (confusion)

12. Remya Bacterial Meningitis The symptoms develop within 3-7 days after exposure. Infants younger than one month old are at a higher risk for severe infection. In newborns and infants, the classic symptoms of fever, headache, and neck stiffness may be absent or difficult to notice. The infant may appear to be slow or inactive, irritable, vomiting or feeding poorly. In young children, doctors may also look at the child’s reflexes, which can also be a sign of meningitis. Although the early symptoms of viral meningitis and bacterial meningitis may be similar, later symptoms of bacterial meningitis can be very severe (e.g., seizures, coma).

13. Neonatal meningitis Those with low birth weight are at increased risk for meningitis - immature immunological status. The most frequent are group B hemolytic streptococci (GBS) and E. coli. May occur by routes such as nosocomial infection. The infant may also be infected from the mother. For example, with women vaginally colonized by GBS, the infant may swallow maternal secretions such as infected amniotic fluid during delivery.

14. Neonatal meningitis often leads to permanent neurologic sequelae such as cerebral or cranial nerve palsy, epilepsy, mental retardation or hydrocephalus. This is partly because the clinical diagnosis of meningitis in the neonate is difficult, perhaps with no more specific signs than fever, poor feeding, vomiting, respiratory distress or diarrhea. In addition, due to the possible range of etiological agents, 'blind' antibiotic therapy in the absence of susceptibility tests may not be optimal, and adequate penetration of the antibiotic into the CSF is also an issue.

15. Group B streptococci Beta hemolysis, Bacitracin resistance

16. Listeria monocytogenes meningitis Meningitis in immunocompromised adults, especially in renal transplant and cancer patients Listeria monocytogenes is a Gram-positive coccobacillus. It also causes intrauterine infections and infections of the newborn.

17. Remya Listeria monocytogenes L. monocytogenes is less susceptible than Strep. pneumoniae to penicillin, and the recommended treatment is a combination of penicillin or ampicillin with gentamicin. Ampicillin is given in typical meningitis doses (2 g intravenously every four to six hours in adults) and gentamicin is used for synergy An alternative in penicillin-allergic patients is trimethoprim-sulfamethoxazole (dose of 10/50 mg/kg per day in two or three divided doses) The usual duration of therapy is at least three weeks

18. E.coli Infection in babies may occur during delivery, or from bacteria acquired in hospital, or in the home. Premature and low-birth-weight babies are at higher risk of contracting meningitis. Infection by E. coli and similar bacteria tend to cause septicaemia (blood-poisoning) when it happens at birth or in the first two days after birth. When it occurs in babies more than 48 hours old it is more likely to cause meningitis. Remya

19. Enteric Gram negative rods Prior to the availability of third generation cephalosporins, it was often necessary to instill an aminoglycoside antibiotic such as gentamicin directly into the cerebral ventricles It is now possible to cure these infections with high doses of third generation antibiotics A repeat CSF sample should be obtained for culture two to four days into therapy to help assess the efficacy of treatment The duration of therapy should be at least three weeks

20. Remya Neisseria meningitidis Most Deadly form of Bacterial Meningitis (also called meningococcal meningitis) Humans are only host of bacteria, it is present in the nasopharynx 11-19% of people who have recovered suffer from permanent hearing loss, mental retardation, or other serious health problems. 10-14% of cases are fatal

21. Remya Meningococcemia When Neisseria meningitidis bacteria enter the bloodstream and multiply, they damage the walls of the blood vessels and cause bleeding into the skin and organs. Symptoms may include fever, fatigue, vomiting, cold hands and feet, cold chills, severe aches or pain in the muscles, joints, chest or abdomen, rapid breathing, diarrhea — and, in the later stages, a puerperal rash or a petechial rash. Meningococcemia is very serious and can be fatal. In fatal cases, deaths can occur in as little as a few hours. In non-fatal cases, permanent disabilities can include amputations or severe scarring as a result of skin grafts.

22. Remya Neisseria meningitidis This infection is best treated with penicillin Although there are scattered case reports of N. meningitidis resistant to penicillin, such strains are still very rare A third-generation cephalosporin is an effective alternative to penicillin for meningococcal meningitis A five day duration of therapy is adequate However, when penicillin is used, there may still be pharyngeal colonization with the infecting strain. As a result, the index patient may need to take rifampin, a fluoroquinolone, or a cephalosporin

23. Remya Haemophilus influenzae type b H. influenzae is a Gram-negative coccobacillus. There are six types (a-f) of H. influenzae, distinguishable serologically by their capsular polysaccharides Unencapsulated strains are common and are present in the throat of most healthy people. Common secondary invader in the lower respiratory tract. The capsulated type b, a common inhabitant of the respiratory tract of infants and young children very occasionally invades the blood and reaches the meninges.

24. Acute H. influenzae meningitis is commonly complicated by severe neurologic sequelae. The incubation period of H. influenzae meningitis is 5- 6 days, and the onset is often more insidious than that of meningococcal or pneumococcal meningitis. The condition is less frequently fatal, but, as with meningococcal infection, serious sequelae such as hearing loss, delayed language development, and mental retardation and seizures may occur. General diagnostic features are the same as for meningococcal meningitis.

25. Maternal antibody protects the infant up to 3-4 months of age, but as it wanes, there is a 'window of susceptibility' until the child produces his/her own antibody. Anticapsular antibodies are good opsonins, which allow the bacteria to be phagocytosed and killed, but children do not generally produce them until 2-3 years of age, possibly because these antibodies are T independent. An effective Hib vaccine, suitable for children 2 months of age and upwards, is available. Close contacts of patients are sometimes given rifampicin prophylaxis.

26. Remya Streptococcus pneumoniae Capsulated Gram-positive coccus carried in the throats of many healthy individuals. Invasion of the blood and meninges is a rare event, but is more common in the very young (<2 years of age), in the elderly, in those with sickle cell disease, in debilitated or splenectomized patients and following head trauma. Overuse of antibiotics contributes to emerging drug resistance in this strain. Alpha hemolysis, Optochin sensitive.

27. Susceptibility to infection is associated with low levels of antibodies to capsular polysaccharide antigens: antibody opsonizes the organism and promotes phagocytosis, thereby protecting the host from invasion. However, this protection is type-specific and there are more than 85 different capsular types of Strep. pneumoniae. The clinical features of pneumococcal meningitis are generally worse than with N. meningitidis and H. influenzae. Pneumococcal meningitis

28. The general diagnostic features are the same as for meningococcal meningitis Since penicillin-resistant pneumococci have been observed worldwide, attention must be paid to the antibiotic susceptibility of the infecting strain, and empiric chemotherapy usually involves a combination of vancomycin and either cefotaxime or ceftriaxone. An effective heptavalent protein-conjugate pneumococcal vaccine is available which the US Centers for Disease Control recommends for all children from 2 to 23 months of age (i.e. to be given with other recommended childhood vaccines) and for older children (24-59 months) who are at high risk (e.g. sickle cell disease, HIV infection, chronic illness or weakened immune systems) for serious pneumococcal infection. The older 23-valent polysaccharide vaccine remains available for children older than 5 years of age.

29. Tuberculous meningitis Patients with tuberculous meningitis always have a focus of infection elsewhere, but approximately 25% may have no clinical or historic evidence of such an infection. In >50% of cases, meningitis is associated with acute miliary tuberculosis. In areas with a high prevalence of tuberculosis, meningitis tends to be most commonly seen in children from 0 to 4 years of age. However, in areas where tuberculosis is less frequent, most meningitis cases are in adults.

30. Tuberculous meningitis usually presents with a gradual onset over a few weeks. There is a gradual onset of generalized illness beginning with malaise, apathy and anorexia and proceeding within a few weeks to photophobia, neck stiffness and impairment of consciousness. Occasionally, the onset is much more rapid and may be mistaken for a subarachnoid hemorrhage.

31. The variability of presentation means that the clinician needs to maintain an awareness of possible tuberculous meningitis to make the diagnosis. A delay in making the diagnosis and in starting appropriate antimicrobial therapy results in serious complications and sequelae. Spinal tuberculosis is uncommon now except in resource-poor countries; bacteria in the vertebrae destroy the intervertebral disks to form epidural abscesses. These compress the spinal cord and lead to paraplegia. Remya

32. Pathogenesis

33. Bacterial meningitis occurs when bacterial virulence factors overcome host defense mechanisms that normally protect against CNS (Central Nervous System) infection in the subarachnoid space to elicit inflammatory responses from the host,and pathophysiological alterations such as pleocytosis and BBB (Blood-Brain Barrier) disruption. Other routes of bacterial entry into the CNS,which occur less commonly,include spread from a contiguous source of infection (such as in cases of sinusitis or mastoiditis) and direct inoculation into the CSF (Cerebrospinal Fluid) in cases of skull fracture or ventricular shunts. After survival and replication in the bloodstream,the microorganisms travel through the blood and may cross the BBB and invade the subarachnoid space. In the bloodstream,infection-causing microorganisms are fought off by WBC (White Blood Cells),an important part of the immune system. However,Host defense mechanisms are unable to control infection in the CSF because of relatively low levels of local antibody and complement activity. Bacterial replication and accumulation of WBCs in the CSF enhance a local inflammatory response in the subarachnoid space because of production and release of inflammatory mediators. These proinflammatory and toxic compounds lead to pleocytosis and increased BBB permeability—the hallmarks of bacterial meningitis. Several mediators contribute to the migration of WBCs particularly neutrophils across the BBB and increased BBB permeability during bacterial meningitis. These include Cytokines,Chemokines,ROS (Reactive Oxygen Species),NO (Nitric Oxide),MMPs (Matrix Metalloproteinases),Arachidonic Acid metabolites,PAF (Platelet Activating Factor),proinflammatory neuropeptides,Endothelins,EAA (Excitatory Amino Acids) and Caspases. Downregulation of these mediators is recognized as a potential target for adjunctive therapy for bacterial meningitis CytokinesChemokinesMMPsEndothelinsCaspases

34. Remya How is it diagnosed? When patient presents symptoms of meningitis, a sample of CSF is acquired from a spinal tap, which is then analyzed for bacterial presence.

35. Remya Early diagnosis and treatment are very important. If meningitis is suspected, samples of blood or cerebrospinal fluid are collected and sent to the laboratory for testing. It is important to know the specific cause of meningitis because the severity of illness and the treatment will differ depending on the cause. Preliminary microscopy results involving white cell counts and Gram-staining for bacteria should be available within an hour of receipt of the CSF sample in the laboratory. Laboratory diagnosis

36. Remya CSF analysis – The CSF can be diagnostic, and every patient with meningitis should have CSF obtained unless the procedure is contraindicated Chemistry and cytologic findings highly suggestive of bacterial meningitis include a CSF glucose concentration below 45 mg/dL, a protein concentration above 100 mg/dL, a white blood cell count above 1000/mm3 turbidity a CSF glucose to Blood glucose ratio <0.1

37. A Gram stain should also be obtained The Gram stain is positive in up to 10 percent of patients with negative CSF cultures and in up to 80 percent of those with positive cultures Results of culture of CSF and blood should follow after 24 h Growing the bacteria in the laboratory is important for confirming the presence of bacteria and for identifying the specific type of bacteria that is causing the infection. Blood cultures are often positive, and can be very useful in the event that CSF cannot be obtained before the administration of antimicrobials At least one-half of patients with bacterial meningitis have positive blood cultures, with the lowest yield being obtained with meningococcus

39. Remya LP changes after antibiotics. Prior antibiotic use reduces the sensitivity of CSF gram stain by 20% and CSF culture by 30%. It takes 24-36 hours of therapy before >90% of CSF cultures will be sterile. It takes 2-3 days of therapy to change the WBC cell count of CSF in true bacterial meningitis. Prior treatment is not an excuse for not doing an LP!

40. Remya But the lab needs…. Specimens before treatment ideally CSF must be processed within 1 hour of collection –CSF cannot be kept in a fridge –Keep CSF in an incubator only if the temperature is < 15 0 C and if it cannot be taken to the lab quickly.

41. Remya Treatment Bacterial meningitis can be treated with a number of effective antibiotics. It is important that treatment be started early in the course of the disease. If bacterial meningitis is suspected, initial treatment with ceftriaxone and vancomycin is recommended. Appropriate antibiotic treatment of the most common types of bacterial meningitis should reduce the risk of dying from meningitis to below 15%, although the risk is higher among the elderly.

43. Remya Immunoprophylaxis There are vaccines for 4 bacteria that can cause meningitis: Neisseria meningitidis Streptococcus pneumoniae Haemophilus influenzae type b (Hib) TB- BCG prevents spinal and meningeal TB

44. Remya Meningococcal vaccines 2 kinds of vaccines Meningococcal polysaccharide vaccine has been approved by the FDA and available since 1981. Meningococcal conjugate vaccines (2005 and 2010). Meningococcal vaccines cannot prevent all types of the disease, but they do protect many people who might become sick if they didn't get the vaccine. Meningococcal conjugate vaccine is routinely recommended for all 11 through 18 year olds and for certain high-risk children and adults.

45. Remya Pneumococcal vaccines 2 types of pneumococcal vaccine Polysaccharide vaccine and a conjugate vaccine. The pneumococcal conjugate vaccine (2000/10) was the first pneumococcal vaccine for use in children under the age of 2 years. Pneumococcal vaccines for the prevention of disease among children who are 2 years and older and adults have been in use since 1977. 23-valent polysaccharide vaccine (PPSV) that is currently recommended for use in adults who are 65 years of age and older, for persons who are 2 years and older and at high risk for pneumococcal disease (including those with sickle cell disease, HIV infection, or other immunocompromising condition), and for persons 19-64 years of age who smoke or have asthma.

46. Remya Hib vaccines The Haemophilus influenzae type b (Hib) vaccine is highly effective against bacterial meningitis caused by a type of bacteria called Haemophilus influenzae type b. The Hib vaccine can prevent pneumonia (lung infection), epiglottitis (a severe throat infection), and other serious infections caused by Hib bacteria. It is recommended for all children under 5 years old in the US, and it is usually given to infants starting at age 2 months. Hib vaccine can be combined with other vaccines.

47. References http://www.cdc.gov Mims et al Medical Microbiology 3E