2.3.9.1 Treatment of bacterial meningitis
The choice of antibiotics in patients with bacterial meningitis is a three stage process with initial empirical decisions based on clinical manifestations, modified once CSF gram stain is available and then again if the CSF culture results are positive (McGill et al., 2016). Antibiotics should be administered imperically to all patients with suspected bacterial meningitis. McGill et al. (2016) and Tunkel (2014) insist that third generation cephalosporins have known bactericidal activity for pneumococci, meningococci (Table 2.4) and penetrate inflammed meninges as such they are the empirical antibiotics of choice in most settlings where resistance rates are low (McGill et al., 2016).
Table 2.4: Empirical antibiotic treatment for bacterial meningitis (McGill et al. 2016)
AGE PREFERRED CHOICE ALTERNATIVE CHOICE Adults < 60 years of age Cefotaxime
OR Ceftriaxone
Chloramphenicol
Adults ≤60 years of age Cefotaxime OR Ceftriaxone AND Amoxicillin Chloramphenicol AND Co-trimoxazole of trimethoprim component
Antimicrobial penetration into the CSF is dependent on lipid solubility, molecular size, capillary and choroid plexus efflux pumps, protein binding and the degree of inflammation of the meninges (McGill et al., 2016). Although there is little high quality trial evidence to guide the antibiotics used in suspected meningitis and meningococcal sepsis, the choice of empirical antibiotics is based largely on known pharmakokinetics, possible aetiological agent of meningitis and known or suspected antimicrobial resistance pattern (McGill et al., 2016). A definitive antimicrobial treatment should commence depending on the microbiology results (Table 2.5).
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Table 2.5: Definitive antibiotic treatment for bacterial meningitis (obtained from McGill et al., 2016)
AETIOLOGICAL AGENT ANTIBIOTIC ALTERNATIVE ANTIBIOTIC CHOICES
N. meningitidis Cefotaxime OR Ceftriaxone Chloramphenicol (if anaphylaxis) OR
Benzylpenecillin
S. pneumoniae
(Sensitivities unknown or Penicillin resistant, Cephalosporin sensitive)
Cefotaxime OR Ceftriaxone Chloramphenicol
S. pneumoniae (Penicillin sensitive
MIC ≤ 0.06 mg/L)
Benzylpenicillin OR Cefotaxime OR Ceftriaxone Chloramphenicol
S. pneumoniae (Penicillin and Cephalosporin
non-susceptible,
Penicillin MIC > 0.06 mg/ml or Cefotaxime / Ceftriaxone MIC >0.5 mg/ml Cefotaxime OR Ceftriaxone AND Vancomycin OR Rifampicin Chloramphenicol
L. monocytogenes Amoxicillin Co-trimoxazole
H. influenzae Cefotaxime OR Ceftriaxone Moxifloxacin
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2.3.9.2 Treatment of fungal meningitis
Although recent guidelines have made attempts to standardise antifungal susceptibility testing, limitations still exist as a result of the incomplete relationship between in-vitro susceptibility and clinical response to treatment (Kanafani & Perfect, 2008). Amphotericin B is the drug of choice due to its fungicidal activity (Toprak, Demir,Kadayifci, Turel, Soysal & Bakir, 2015) but some resistant strains to this drug have been reported (Kanafani & Perfect, 2008).
Meningitis caused by C. neoformans and C. albicans should be treated with Amphotericin B and flucytosine in combination followed by fluconazole (Schmiedel & Zimmerli, 2016; Toprak et al., 2015). There are no widely accepted guidelines in relation to the time span of antifungal therapy for CNS fungal infection. Once antifungal treatment has commenced it should proceed until WBC count, glucose and protein levels are back within normal reference ranges, culture is sterile and the patient signs and syptoms cease to exist (Toprak et al., 2015).
2.3.9.3 Treatment of syphyIitic meningitis
For treatment of relapsed syphilis (primary, secondary or latent), benzathine penicillin G 2.4 units IM is administered for three weeks till CSF investigations show that neurosyphilis is absent. If CSF investigation show positive result for neurosyphilis, the recommended therapy is acqueous crystalline penicillin G (Centres for Disease Control and Prevention, 2015; Ahsan & Burrascano, 2015) 18-24 million units per day given as 3-4 million units IV every 4 hours or continuous infusion for 10-14 days (Ahsan & Burrascano, 2015). 2.3.9.4 Treatment of parasitic meningitis
The choice of drug for treatment of parasitic meningitis depends on the parasite infecting the CNS. Graeff-Teixera, Da Silva and Yoshimura (2009) highlighted that corticoids and antihelminths are used to treat parasitic meningitis. For instance, albendazole, a benzimidazole derivative, has been utilised in human angiostrongyliasis (Jitpimolmard, Sawanyawisuth, Morakote, Vejjajiva, Puntumetakul, Sanchaisuriya & Tassaneeyakul, 2006). Albendazole eliminates angiostrongyliasis by binding to parasite beta-tubulin, blocking worm polymerilisation and inhibiting glucose uptake (Jitpimolmard et al., 2006; Centres for Disease Control & Prevention, 2014). Eflornithine has been used to treat
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West African trypanosomiasis. Melarsoprol is a more toxic alternative used to treat meningitis caused by trypanosomes (Eneh, Uwaezuoke, Edelu & Ogbuka, 2016).
2.3.9.5 Prevention of meningitis
There are a number of ways of preventing meningitis. According to the Centres for Disease Control and Prevention (2016), the most effective way to protect against certain types of bacterial meningitis is vaccination. Vaccines are available for three types of bacteria; N. meningitidis, S. pneumoniae and H. influenzae. Maintenance of good health habits such as not smoking and avoiding cigarette smoke, getting plenty of rest and avoiding close contact with people who are sick may also prevent from getting bacterial meningitis (Centres for Disease Control and Prevention, 2016).
Prevention of fungal meningitis involves avoiding endemic areas and maintaining one’s immune system healthy (Bauman, 2014, p. 691). Given that fungal infections mostly attack immunosuppressed individuals, the underlying risk factors leading to immunosuppression need to be eradicated to acquire best results from the fungal therapy (Murray, Kobayashi, Pfaller & Rosenthal, 1994, p. 434). People who are immunosuppressed should deter birds droppings, places where birds roost at night (Bauman, 2014, p. 702; Centres for Disease Control and Prevention, 2016), cultivating in fields and other dusty related activities (Centres for Disease Control and Prevention, 2016). Patients who are on catheters must be observed frequently and lines must be changed regularly so that they do not become a source of fungal infection (Murray et al., 1994, p. 434).
Public education on good hygiene practices are essential for preventing parasitic meningitis. Infection with T. gondii can be prevented by washing fruits and vegetables before eating, washing utensils, dishes, counters with hot soapy water after contact with raw meat, freezing meat for several days at sub-zero (0oF) temperatures before cooking
to reduce the chances of infection, wearing gloves when hoeing (Centres for Disease Control and Prevention, 2013). T. gondii is found in faeces of infected cat. Cats should be fed with only dried commercial food or well cooked table food. Handling of stray cats should be avoided (Centres for Disease Control and Prevention, 2013). Ingestion of undercooked meat should also be avoided to prevent infection from A. cantonensis
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(Centres for Disease Control and Prevention, 2010) and T. gondii (Centres for Disease Control and Prevention, 2013). Trypanosomes which cause meningitis in man are transmitted by tsetse flies of Glossina species. Control measures are targeted at minimising contact with tsetse flies. Some actions that may be taken to prevent bites from tsetse flies are (Centres for Disease Control and Prevention, 2012);
check vehicles before entering. The flies are attracted to the motion and dust from moving vehicle.
Wear long sleeved shirts and pants of medium-weight material that mix with the background environment. Tsetse flies like bright or dark colours and they can bite through lightweight clothing.
Keep away from bushes.
Public education on the impact of syphilis is important in the prevention of neurosyphilis, symptoms for medical attention and behavioural changes such as safer sex practices (Singh & Romanowski, 1999). Screening of syphilis is necessary for several reasons; it reduces transmission of the disease, prevents complications of syphilis and in pregnant mothers it prevents transmission of the disease to the newborn baby (Centres for Disease Control and Prevention, 2016; Singh & Romanowski, 1999).