Question

for bacterial meningitis, it is also important to know which bacteria causing meningitis because antibiotics can prevent some types from spreading and infecting other people. briefly discuss chemoprophylaxis for contacts of meningococcal disease, specifying antimicrobials which have proved effective

Answer 1

Meningococcal disease is a serious and potentially life-threatening infection caused by the bacterium Neisseria meningitidis Common symptoms of meningococcal disease include high fever, neck stiffness, confusion, nausea, vomiting, lethargy, and/or petechial or purpuric rash. Without appropriate and urgent treatment, the infection can progress rapidly and result in death.

Introduction :

Meningococcal disease is caused by the gram-negative bacterium Neiserria meningitidis (meningococcus) and infection usually presents as meningitis, septicaemia or a combination of the two. Overall mortality remains high, about 10%, despite antibiotic therapy. N. meningitidis is carried and transmitted only by humans. Asymptomatic nasopharyngeal carriage is common and seen in about 10% of the population.

Transmission and carriage :

A patient with meningococcal disease is not a good transmitter of the disease. It is a carrier, who may have had been carrying the organism for some time (but not been unwell themselves), who is more likely to transmit the meningococcus again and cause further cases. Secondary cases are rare and generally occur within the first 48 hours although there is a prolonged but low risk of secondary transmission within households extending up to several weeks. The main reason for giving clearance antibiotics is to eliminate meningococci from any carrier who may be in the network of contacts close to each index case. This reduces the risk to other susceptible individuals in the network protecting them from acquiring meningococcus from the carrier and possibly developing invasive disease.

Definition of close contacts:

Risk factors for invasive meningococcal disease include age, crowding, lower socioeconomic status, smoking and exposure to smokers, recent illness, sharing a bedroom and intimate kissing. There are a number of settings with a well established increased risk of secondary cases due to close and prolonged contact with the carrier. These include: 1) Household contacts - includes recent visitors who have stayed overnight in the 7 days preceding the case’s illness; those who share the same dormitory, military barracks, hostel bunkroom. Should receive clearance antibiotics and vaccination. 2) Sexual contacts – sexual partner(s) of case + intimate kissing partners. Should be treated as household contacts and receive clearance antibiotics and vaccination. 3) Travel contacts - seated immediately adjacent to a case on flight > 8 hours in duration. Should receive clearance antibiotics. 4) Childcare contacts – children and staff in same room group at a child-care facility attended by index case for one period of ≥ 4 hours in 7 days preceding onset of case’s illness require clearance antibiotics. 5) School and University contacts – depending of the nature of the contact and whether it occurred in relation to a specific outbreak (eg. related to a particular class) then clearance antibiotics may be appropriate. 6) Health care worker contacts – only medical personnel who are directly exposed to a case’s nasopharyngeal secretions (ie: person who intubated case if facemask NOT worn, or performed mouth-to-mouth resuscitation) require clearance antibiotics. Other healthcare staff members, involved in managing the patient, do not require clearance antibiotics. The risk to health care workers is estimated to be 0.8 per 100,000 health care workers at risk, which is 25 times that of the general population. The excess risk is small and inappropriate use of clearance antibiotics should be avoided. The public health management of close contacts includes giving appropriate information +/- clearance antibiotics and vaccination.

Chemoprophylaxis

Persons who have had close contact with patients who have meningococcal disease are at greatly increased risk for contracting the disease. The primary means of preventing the spread of meningococcal disease is antimicrobial chemoprophylaxis. Secondary cases are rare as a result of effective chemoprophylaxis for household members, contacts at daycare centers, and anyone else directly exposed to an infected patient’s oral secretions (e.g., kissing, mouth-to-mouth resuscitation). Risk of secondary disease among close contacts is highest during the first few days after the onset of disease, which requires that chemoprophylaxis be administered as soon as possible. If given more than 14 days after the onset of disease, chemoprophylaxis is probably of limited or no benefit.[6] Oropharyngeal or nasopharyngeal cultures are not useful in determining the need for chemoprophylaxis and may unnecessarily delay the use of effective preventive measures (Table 1).

In areas of the United States where ciprofloxacin-resistant strains of N. meningitidis have been detected, ciprofloxacin should not be used for chemoprophylaxis. Use of azithromycin as a single oral dose has been shown to be effective for eradication of nasopharyngeal carriage and can be used on a limited basis where ciprofloxacin resistance has been detected.[18]

Table 1. Recommended chemoprophylaxis regimens for high-risk contacts and persons with invasive meningococcal disease.

Drug	Age	Dose	Duration	Efficacy (%)	Cautions
Rifampin	<1 mo	5 mg/kg, orally, every 12 h	2 days
Rifampin	≥1 mo	10 mg/kg (maximum 600 mg), orally, every 12 h	2 days	90-95	Can interfere with efficacy of oral contraceptives and some seizure prevention and anticoagulant medications; may stain soft contact lenses. Not recommended for pregnant women.
Ceftriaxone	<15 y	125 mg, intramuscularly	Single dose	90-95	To decrease pain at injection site, dilute with 1% lidocaine.
Ceftriaxone	≥15 y	250 mg, intramuscularly	Single dose	90-95
Ciprofloxacin	≥18 y	500 mg, orally	Single dose	90-95	Not recommended for persons <18 years of age. Not recommended for pregnant women.
Azithromycina		10 mg/kg (maximum 500 mg)	Single dose	90	Not recommended routinely. Equivalent to rifampin for eradication of Neisseria meningitidis from nasopharynx in one study