Trop Doct 2008;38:222-224
doi:10.1258/td.2007.070296
© 2008 Royal Society of Medicine Press
The rise and fall of epidemic Neisseria meningitidis from a tertiary care hospital in Delhi, January 2005–June 2007
Surinder Kumar MD MNAMS
Bineeta Kashyap MBBS MD
Preena Bhalla MBBS MD
Department of Microbiology, Maulana Azad Medical College, New Delhi 110 002, India
Correspondence to: Dr Bineeta Kashyap, Flat No. C-402, Plot No. 03, Vimal CGHS Ltd, Sector –12, New Delhi 110075, India Email: dr_bineetakashyap{at}yahoo.co.in
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SUMMARY
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Meningococcal meningitis is endemic in India. There has been
a sudden surge of cases of meningococcal meningitis in 2005
in Delhi. Present study was undertaken to find out changing
trends in incidence of this disease from a tertiary care hospital
in New Delhi over a period of two and half years. All samples
from suspected cases of meningococcal meningitis were subjected
to Gram staining, culture and latex agglutination test for detection
of
Neisseria meningitidis (
N.meningitidis). Antimicrobial susceptibility
of all isolates was performed using the disc diffusion test.
78.6%, 71.4% and 100% of the samples were positive for
N.meningitidis by smear examination, culture and latex agglutination test respectively.
Except for resistance to Penicillin and Erythromycin in 8.8%
and 5.9%, the isolates were sensitive to the commonly used antibiotics.
Using simple, rapid and reliable methods for diagnosis, defining
risk factors and continuing surveillance remain important public
health goals for the control of meningococcal disease.
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Introduction
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Sporadic outbreaks of meningococcal disease are a significant
cause of mortality and morbidity throughout the world. In India,
it occurs sporadically but with epidemics occurring at regular
intervals.
1 Although the rates of endemic meningococcal disease
range from one to 3/100,000 in the USA to 10 to 25/100,000 in
the developing world, it is noted for causing major epidemics
with attack rates exceeding 500/100,000.
2 Fifty percent of cases
occur in children and adolescents under 19 years of age, with
the highest risk in children under five years.
3 The largest
outbreaks have been in sub-Saharan Africa (the African Meningitis
Belt).
1 Meningococcal disease is endemic in Delhi and sporadic
cases have occurred in previous years.
4 Since 1966, Delhi has
faced repeated epidemics (Figure
1).
This study was undertaken in order to gain an understanding
of these outbreaks and to provide information on the potential
for future epidemics. We also wanted to observe the changing
trends in the incidence of meningococcal meningitis during January
2005–June 2007 in a tertiary care hospital caring for
those in Delhi and the adjoining states. We studied the antibiotic
sensitivity pattern of
Neisseria meningitidis and compared the
latex agglutination test (LAT) with Gram stain and culture in
a rapid diagnosis of meningococcal meningitis.
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Materials and methods
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Samples were obtained from patients suspected of having meningococcal
meningitis admitted to the Lok Nayak Hospital between January
2005 and June 2007 and were received by the Department of Microbiology,
Maulana Azad Medical College, New Delhi.
After 24 hours incubation at 37ºC, subcultures were made from blood culture samples on 5% sheep blood agar (SBA) and MacConkey's agar. After 24 hours incubation, colonies were identified following the standard recommendations.5 A negative culture was reported only after five to seven days of reincubation.
Cerebrospinal fluid (CSF) samples were centrifuged at 1500 rpm for 15 minutes at room temperature. A portion of the deposit was examined microscopically by Gram stain for the presence of pus cells and by Gram-negative diplococci (GNDC). Another portion was cultured on 5% SBA and chocolate agar and incubated at 37ºC in a candle jar. The remaining portion was put in to a glucose broth and incubated at 37ºC. Colonies were identified by the standard method after 24 hours of incubation.5 Where there was no growth or a turbid glucose broth, a subculture from a glucose broth was further examined.
The supernatant was utilized for antigen detection by LAT using a Pastorex® meningitis kit (Bio-Rad, Marnes-la-Coquette, France) as per the manufacturer's instructions. All isolates obtained were serogrouped using LAT.
Antimicrobial susceptibility testing was performed on Mueller–Hinton agar (Hi media, Mumbai, India) by disk diffusion as recommended by the Clinical and Laboratory Standards Institute.6 The antibiotics used were penicillin, erythromycin, amoxicillin, ciprofloxacin, ceftriaxone, cefotaxime, meropenem and chloramphenicol.
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Results
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Monthly frequency and demographic profiles of all cases are
shown in Figure
2.
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Figure 2 Monthly frequency of meningococcal meningitis (January 2005–June 2007) (inset shows the age–sex distribution)
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From 20 blood culture samples, we isolated
N. meningitidis on
culture, all of which were identified as group A
N. meningitidis using LAT.
Of the 14 CSF samples, 13 (92.8%) were turbid and were shown to have pus cells on Gram staining. One (7.1%) non-turbid sample did not reveal any pus cell on Gram staining. GNDC were seen in 11 of the 14 (78.6%) samples on Gram staining. Of the three samples that did not show GNDC on Gram staining, one was the sample that was negative for pus cells on direct microscopic examination. Of the CSF samples 71.4% (10/14) were positive for N. meningitidis. However, all four negative culture samples had pus cells and GNDC on Gram stain. All 14 samples (100%) were identified as group A N. meningitidis by LAT.
Except for those that were resistant to penicillin (8.8%), erythromycin (5.9%) and intermediately sensitive to erythromycin (11.8%), all the isolates were sensitive to the remaining antimicrobial agents.
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Discussion
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This study shows an increase in the incidence of meningococcal
meningitis over a span of two and a half years that coincided
with outbreaks in Delhi. The incidence was more common in males
(73.5%) – similar to the male preponderance of 74% seen
in the Delhi outbreak of 2005 and reported by the World Health
Organization.
3 The age distribution of our cases (0–10
years, nine; 11–20, eight; 21–30, 12; 31–40,
3; 41–50, 1; 51–60, 1) suggests that the majority
of cases were found in adolescents and young adults –
which concurs with a previous study by Dutta
et al.7
All our isolates were obtained during December to July as seen in previous reports8 and peaked during May and December.4 In the sub-Saharan ‘meningitis belt’ the epidemics typically start during dry season (January–March) and at the onset of the rainy season (May–June).1
In this study N. meningitidis was confirmed by Gram stain and culture in 91.2% and in 88.2% of the CSF samples. Our isolation rates are higher than previous reports.9 Due to ongoing outbreak in Delhi during the period of our study, the already sensitized clinicians and microbiologists took great care to collect samples prior to patients receiving antimicrobial therapy and processed the samples promptly which might well have affected our results.
LAT could have identified all suspected cases of meningococcal meningitis caused by N. meningitidis. However, although culture is the gold standard and Gram staining correlates with the culture fairly well, during an outbreak diagnosis cannot depend upon these alone as prior antimicrobial therapy can alter the results of both these methods. Hence, LAT can be used as a reliable method for the rapid diagnosis of meningococcal meningitis, but the high cost and non-availability of kits are major constraints in developing countries. Previous studies have advocated the use of LAT as an adjunct in the diagnosis of purulent bacterial meningitis.10
Except for a few of our isolates that exhibited resistance to penicillin and erythromycin, most were sensitive to the commonly used antimicrobial agents. In India, there are not many published studies on the antimicrobial sensitivity of N. meningitidis, but a few have reported sensitivity to the commonly used antibiotics. All isolates obtained from the early 2005 spurt of cases in Delhi were sensitive to penicillin, ampicillin, rifampicin and ceftriaxone, two-thirds were non-susceptible to ciprofloxacin and all were resistant to cotrimoxazole.8
Defining the risk factors and continuing the surveillance of this disease remain important public health goals for the control of meningococcal disease.
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References
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- Rosenstein NE, Perkins BA, Stephens DS, Popovic T, Hughes JM. Meningococcal disease. N Engl J Med 2003;344:1378–88
- Manchanda V, Gupta S, Bhalla P. Meningococcal disease: history, epidemiology, pathogenesis, clinical manifestations, diagnosis, antimicrobial susceptibility and prevention. Indian J Med Microbiol 2006;24:7–19[Medline]
- Public Health Agency of Canada. Reports of Epidemic Meningococcal Activity in India Update: June 14, Ottawa, Ontario, 2005
- CD Alert. Monthly Newsletter of National Institute of Communicable Diseases. Directorate General of Health Services: Government of India; 2005;9:1–8
- Collee JG, Miles RS, Watt B. Tests for the identification of bacteria. In Collee JG, Fraser AG, Marmion BP, Simmons A eds. Mackie & McCartney Practical Medical Microbiology. 14th edn. New York: Longman, 1996:131–49
- Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing; 15th Informational Supplement. CLSI/NCCLS M100-S15. Wayne, PA: Clinical and Laboratory Standards Institute, 2005
- Dutta AK, Sachdeva A, Kukreja S, Jain V. Meningococcal disease – outbreak in Delhi. Indian Pediatr 2005;42:547–56[Medline]
- Traore Y, Njanpop-Lajourcade BM, Adjogble KL, et al. The rise and fall of epidemic Neisseria meningitidis serogroup W135 meningitis in Burkina Faso, 2002–2005. Clin Infect Dis 2006;43:817–22[Medline]
- Ichpujani RL, Rajkumar A, Mohan R, Kumari S, Basu RN. Comparison of direct-microscopy, culture, and latex agglutination tests for diagnosis of meningococcal meningitis. J Commun Dis 1986;18:73–6[Medline]
- Surinder K, Bineeta K, Megha M. Latex particle agglutination test as an adjunct to the diagnosis of bacterial meningitis. Indian J Med Microbiol 2007;25:395–7[Medline]
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SUMMARY
Introduction
