The patient was a 3h-week-old male who was born at term by cesarean section. At

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The patient was a 3h-week-old male who was born at term by cesarean section. At birth he had a left diaphragmatic hernia that was repaired soon thereafter. He required intubation at that time and continued to require respiratory support. Over a 24-hour period, the infant developed bulging anterior fontanelles, increased respiratory and heart rates, wide fluctuations in blood pressure, and difficulties maintaining adequate tissue perfusion, and his periph- eral white blood cell (WBC) count increased from 6,300 to 13700/ul. The child began to have focal seizures as well. A cerebrospinal fluid (CSF) examina- tion showed 3,900 WBC/ul with 92% neutrophils, glucose level of 2 mg/dl, and protein level of 350 mg/dl. Gram stain of the child's CSF is shown in Fig. 1. The organism from the CSF is shown in Fig. 2. . What is your diagnosis for this patient? Is it consistent with his phys- ical and laboratory findings? Explair organism has similar Gram stain and colonial morphology? What trast these two forms. Which form does this patient have? invasive infection with this organism? and discuss its role in pathogenesis of infection. the components that you would include in this vaccine. Who should 2. What is the most likely organism causing his infection? What other simple, rapid test would you use to distinguish these two organisms? 3. There are two forms of this infection in neonates. Compare and con- 4. Beside infections in neonates, what other populations are at risk for 5. Describe the key virulence factor produced by the infecting organism 6. Vaccines are currently under development for this organism. Describe 7. Since vaccines against the organism are not currently available, discuss receive this vaccine? Why would they receive it? strategies for prevention of neonatal infections with this organism. How effective have they been in preventing early-onset disease? How effective have they been in preventing late-onset disease? Figure Figure 2

Explanation / Answer

1.ans. The diagnosis for this patient is of bacterial meningitis. The low glucose level , increased WBC count and high protein level in the CSF is indicative of the disease.Meningitis is an inflammation of the meninges membranes surrounding the brain and spinal cord.The bulged anterior fontanelles, increased heart rate ,blood pressure fluctuations are signs of meningitis.The CSF examination only confirms the diagnosis.So, the diagnosis is consistent with physical and laboratory findings.

2.ans.The most likely organism causing this meningitis is gram negative bacteria. Meningococcal bacteria causing sepsis gives similar kind of stain. A simple glass test distinguishes beween septicaemia and meningitis.

3.ans.The two forms of this infection in the neonates are viral and bacterial meningitis.

In bacterial meningitis,the bacteria enter the bloodstream and then travel to the meninges. It may also happen that the bacteria directly enters the meninges through sinus or ear infections.Acute bacterial meningitis must be treated at once with intravenous antibiotics or corticosteroids. This ensures recovery and minimises risk of complications.The antibiotic/combination of antibiotics depends on the type of bacteria causing the infection.

Several strains of bacteria cause acute bacterial meningitis:

Viral meningitis is usually mild and subsides on its own. Echovirus groups of enteroviruses are the most common cause of viral meningitis,which are most common in late summer and early fall. Viruses such as herpes simplex virus, HIV, mumps, West Nile virus and others also can cause viral meningitis.. Most infections produce no symptoms, or mild symptoms such as sore throats, colds and flu-like illnesses. Some of them may also cause stomach upsets and diarrhoea.Enteroviruses mostly affect children, who are the main transmitters of these viruses.

The patient here is infected by Meningococcal meningitis caused by Neisseria meningitidis.

4.ans.Age:Elderly patients can be infected by bacterial meningitis having comorbid conditions that affect the immune system. Symptoms can be atypical, and neck stiffness and headache are less frequently present, while focal neurological abnormalities occur more often.

community based infection:Infectious diseases tend to spread where large groups of people gather together. College campuses have reported outbreaks of meningococcal disease, caused by N. meningitidis.

Medical conditions:There are certain medical conditions, medications and surgical procedures that exposes the risk of people getting infected with meningitis.

Working with meningitis pathogen:Microbiologists routinely exposed to meningitis-causing bacteria are at increased risk for meningitis.

5.ans.Neisseria meningitidis is the pathogen responsible for Meningococcal meningitis. The bacterium has a number of virulence factors of which the antiphagocytic polysaccharide capsule renders the maximum contribution towards its virulence. Other virulence factors include, IgA protease, lipo-oligosaccharide and fimbriae [pili].The presence of capsules in pathogenic N. meningitidis serve to provide resistance against antibody, complement-mediated lysis and phagocytic destruction by the host immune response. Serogroups B, C, W-135, and Y aids in incorporation of sialic acids into the capsule mimicking the host cell surfaces. This helps in evading the immune response as sialic acids are commonly found on several host cell surfaces. A phenomenon identified as capsule switching occurs between the serogroups which allows horizontal exchange of the capsule operon.As a consequence of this, anticapsular antibodies are unable in eliminating the pathogen.

6.ans.The Menhibrix vaccine prevents against pathogenetic attack of Neisseria meningitidis serogroups C , Y and Haemophilus influenzae type b(Hib). This is the first meningococcal vaccine that can be given to six week old infants.

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