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Fluorescence microscopy

Bacti pathogenesis


Clinical Microbiology
Clinical bacteria gnc animation microscope
Gram-negative cocci, aerobic.

"The family Neisseriaceae comprises the genera Neisseria, Moraxella, Kingella, and Acinetobacter. The only significant human pathogens are N gonorrhoeae, the agent of gonorrhea, and N. meningitidis, an agent of acute bacterial meningitidis. N gonorrhoeae infections have a high prevalence and low mortality, whereas N meningitidis infections have a low prevalence and high mortality. Moraxella is an oxidase-positive bacterium, sometimes mistaken for Neisseria, that may be isolated from eye infections and respiratory tract infections. Moraxella catarrhalis causes lower respiratory infection in adults with chronic lung disease and is a common cause of otitis media, sinusitis, and conjunctivitis in children. Kingella and Eikenella species are short bacilli or coccoid bacteria that act as opportunistic pathogens. They are sometimes secondary invaders of damaged tissues."


GNDCNeisseria gonorrhoeae is a fastidious organism requiring growth factors which are present in hemolyzed blood cells. Thayer-Martin chocolate agar plates have VCN antibiotics which prevent growth of most organisms while supporting N gonorrhoeae growth. The gram stain is considered by many as the single most important characteristic of clinical bacteria. However the gram stain itself is not used for the identification of organisms. One rare exception would of course be a gram stain of urethral discharge which contains gram negative cocci in pairs inside neutrophils. GNID, gram-negative intracellular diplococci. are widely regarded as pathonomonic for Neisseria gonorrhoeae infection. On gram-stain they are among the smallest of bacteria. As a result, it takes a little practice to be able to quickly recognize their distinctive diplococcoid shape. You may have heard the term, "kidney bean shaped." But they are so small that you have to have an imagination to see that. When seen in the pus of a urethral smear their presence is usually so obvious as to be unmistakable. There will almost always be wall to wall neutrophils which microbiologists have a habit of calling PMN's or polymorphonuclear leukocytes since they are gram stained and not stained with a Wright's stain.. And the tiny diplococci must be seen within the boundaries of some of the PMN's to qualify as GNID.

In Japan infection with this organism is so uncommon that it is classified as "rare."

"The only distinguishing structural feature between N meningitidis and N gonorrhoeae is the presence of a polysaccharide capsule in the former. The capsule is antiphagocytic and is an important virulence factor."


Here is a GNID image from "Doc" Kaiser's collection. http://www.cat.cc.md.us/~gkaiser/labmanua/lab16/gc.html

GNDCUrethral Smear GNID, Loyola University website:

Neisseria gonorrhoeae

SEM x27,200 electron micrograph courtesy of Dennis Kunkel. Click thumbnail to go to the EM website.

Also the image gallery at ASM: asmusa.org


GNDCNeisseria meningitidis in meningococcal disease:
The MMWR lists a cumulative total of 19,870 cases of meningococcal disease for 1999.
"Before the 1990s, Haemophilus influenzae type b (Hib) was the leading cause of bacterial meningitis, but new vaccines being given to all children as part of their routine immunizations have reduced the occurrence of invasive disease due to H. influenzae. Today, Streptococcus pneumoniae and Neisseria meningitidis are the leading causes of bacterial meningitis."
"High fever, headache, and stiff neck are common symptoms of meningitis in anyone over the age of 2 years.""The diagnosis is usually made by growing bacteria from a sample of spinal fluid. The spinal fluid is obtained by performing a spinal tap, in which a needle is inserted into an area in the lower back where fluid in the spinal canal is readily accessible. Identification of the type of bacteria responsible is important for selection of correct antibiotics." CDC.

If you want to see EM images of N. meningitidis check Dennis Kunkel's EM images. Electron Microscopy

AlsoASMhas a gallery in progress at: MicrobeLibrary.org

Neal'sNeal Chamberlain's site is easy to search for Neisseria meningitidis

"Doc" Kaiser's is a very good site.http://www.cat.cc.md.us/~gkaiser/
Moraxella catarrhalis "Moraxella is oxidase-positive, sometimes mistaken for Neisseria, that may be isolated from eye infections and respiratory tract infections. Moraxella catarrhalis causes lower respiratory infection in adults with chronic lung disease and is a common cause of otitis media, sinusitis, and conjunctivitis in children." "M catarrhalis was formerly placed in the genus Neisseria; however, studies of DNA base content, fatty acid composition, and genetic transformation showed that this organism did not belong in that genus. M catarrhalis is a member of the normal flora in 40-50% of normal school children""M catarrhalis may cause clinical syndromes indistinguishable from those caused by gonococci, and so it is important to distinguish these organisms from one another. Many strains produce ß-lactamase."


Gram negative cocci which are anaerobic.
Veillonella sp. This organism is somewhat difficult to grow in vitro. It is part of the normal mouth flora. Veillonella is sometimes mistaken for GC in (oral) gram stain. Most common species is Veillonella parvula.
Centers for Disease Control
National Center for Infectious Diseases
Division of Bacterial & Mycotic Diseases
Morbidity and Mortality Weekly Report, CDC, epidemiological trends, clear perspective.

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