Last Updated on February 4, 2021 by Sagar Aryal
Neisseria meningitidis and Neisseria gonorrhoeae, are obligate human pathogens that cause distinctly different disease syndromes. They are both Gram negative diplococci, non-sporing, oxidase positive and difficult to differentiate on morphological and cultural characteristics.
However, they can be differentiated on the following grounds:
|2.||Causative agent of||Sexually transmitted disease- Gonorrhoea||Causes a range of diseases embraced by the term invasive meningococcal disease. Most commonly cerebrospinal meningitis.|
|3.||Cell Morphology||Kidney shaped with apposing ends concave.||Semicircular diplococcus with flat apposing ends.|
|4.||Capsule||Absent||Capsule is present which is anti-phagocytic and an important virulence factor.|
|5.||Pili||N. gonorrhoeae most often moves using one retracting pilus.||N. meningitidis most often move using four pili.|
|6.||Plasmids||Usually possess plasmids, coding for drug resistant genes.||Rarely have plasmids|
|7.||Form||Predominantly exist in|
|Exist in both intra· and|
|8.||Movement||Movement of N. gonorrhoeae occurs at lower speed.||Movement of N. meningitidis occurs faster with a larger number of retracting pili.|
|9.||Growth on Blood Agar||N. gonorrhoeae grow less well on blood agar than N. meningitidis.||N. meningitidis grow well on blood agar than N. gonorrhoeae|
|10.||Culture medium||Contain antimicrobials that inhibit the growth of organisms other than N. gonorrhoeae; typically vancomycin (inhibits Gram-positive bacteria), colistin (inhibits gram-negative bacteria including the commensal Neisseria spp.), trimethoprim (inhibits swarming of Proteus spp.) and nystatin or amphotericin B (antifungal agents).||Blood agar, trypticase soy agar, supplemented chocolate agar, and Mueller-Hinton agar.|
|11.||Growth Rate||Slower than Meningococcus.||Slow|
|12.||Fastidious||Most fastidious among Neisseria spp.||Comparatively less fastidious.|
|13.||Colony morphology||N. gonorrhoeae form smooth, round, moist, uniform grey/ brown colonies with a greenish colour underneath on primary isolation medium.|
Mostly, has a irregular margin.
|N. meningitides would form smooth, round, moist, uniform|
large grey/brown colonies with a glistening surface and entire edges.
|14.||Sugar Fermentation||Produce acid from glucose only||Produce acid from glucose and maltose.|
|16.||Nitrite Reduction||N. gonorrhoeae doesn’t reduce nitrites.||N. meningitidis can reduce nitrites in low concentrations.|
|20.||Antigen Heterogeneity||More than meningococci.||Comparatively less.|
|21.||Grouping||Strains characterized by auxotyping which recognizes reqiurements for specific nutrients.||Serogroup is determined by its lipopolysaccharide capsular antigen.|
|22.||Normal Flora||Not considered as normal flora.||Many normal individuals may harbor Neisseria meningitidis in the upper respiratory tract|
|23.||Pathogen||It is always a pathogen.||It may or may not be pathogenic.|
|24.||Portal of Entry||Genital||Respiratory|
|25.||Site of Infection||Primarily causing infection of the anogenital tract.||Colonizes the upper respiratory tract as a commensal and occasionally invades to|
cause systemic disease.
|26.||Virulence Factors||Pili, IgA proteases and production of lipopolysaccharide endotoxin.||LPS capsule, IgA protease and iron utilizationfrom transferrin.|
|27.||Related Conditions||N. gonorrhoeae can also cause conjunctivitis, pharyngitis, proctitis or urethritis, prostatitis, and orchitis.||Cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis.|
|28.||Specimens||Transport swab of endocervix, urethra, rectum, pharynx, conjunctiva, blood, joint fluid, aspirates from skin lesions.||Cerebrospinal fluid (CSF) and blood, swab skin lesions and nasopharynx.|
|29.||Presence in inflammatory exudates (pus)||In larger proportions||In less numbers|
|30.||Prevalence and Mortality||N.gonorrhoeae infections have a high prevalence and low mortality.||N. meningitidis infections have a low prevalence and high mortality.|
|31.||Superbug||Considered as “superbug”||Not considered as “superbug”|
|32.||Vaccines||No||Serogroup A, B, C, Y and W-135 meningococcal infections can be prevented by vaccines.|
- Greenwood, D., Slack, R. C. B., Peutherer, J. F., & Duguid, J. P. (1992). Medical microbiology: A guide to microbial infections : pathogenesis, immunity, laboratory diagnosis, and control. Edinburgh: Churchill Livingstone.
- Sastry A.S. & Bhat S.K. (2016). Essentials of Medical Microbiology. New Delhi : Jaypee Brothers Medical Publishers.
- Parija S.C. (2012). Textbook of Microbiology & Immunology.(2 ed.). India: Elsevier India.