Neisseria gonorrhoeae

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Neisseria gonorrhoeae


Introduction to bacteria

Bacterial structure and functions


Neisseria gonorrhoeae


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High Yield Notes

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Neisseria gonorrhoeae

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USMLE® Step 1 style questions USMLE

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A 22-year-old woman presents to the primary care clinic due to painful urination. Symptoms began three days ago and have progressed to bothering the patient throughout the day. The patient also developed foul-smelling vaginal discharge over the last two days. A Gram stain of a cervical swab is obtained and shown in the figure below. Which of the following characteristics is true regarding the causative pathogen of this patient’s condition?  

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Arthritis p. 476

gonococcal p. 478


for gonococci p. 140

Conjunctivitis p. 553

gonococcal prophylaxis p. 195

gonococci p. 140

Gonococci vs meningococci p. 140


gonococci p. 140

Neisseria gonorrhoeae p. , 140

culture requirements p. 124

Gram-negative algorithm p. 139

osteomyelitis p. 177

septic arthritis p. 478

STI p. 182

UTIs with p. 625

Pelvic inflammatory disease (PID) p. 182

gonococci p. 140


gonococcal arthritis p. 478

Septic arthritis p. 478

gonococci p. 140


Neisseria gonorrhoeae, also known as N. gonorrhoeae to its friends, is a gram-negative oval bacterium that infects humans, causing a number of infections including gonorrhea.

The word Neisseria came from Neisser Albert, a German physician who discovered it, while gonorrhea is from the Greek words “gonos” which means "seed", and “rhoe” which means "flow", meaning "flow of seed", an illustration referring to the penile purulent discharge, which was mistakenly thought to be semen in infected males.

Now, a little bit of microbe anatomy and physiology. N. gonorrhoeae is a gram-negative bacterium, because its cell wall has a thin peptidoglycan layer and so it doesn’t retain purple dye used during Gram staining.

Instead, like any other Gram-negative bacteria, N. gonorrhoeae stains pink with safranin dye.

N. gonorrhoeae typically live in pairs called diplococci, stacked side to side, so the pair looks like a coffee bean.

They are also non-motile, non-spore forming, and obligate aerobes, which means that they absolutely need oxygen to grow.

Finally, they’re catalase and oxidase positive - which means they produce both these enzymes.

N. gonorrhoeae grows on a special chocolate medium called Thayer-Martin agar, which mainly consists of sheep blood... err, yum?

Some antimicrobials, like vancomycin and nystatin are usually added to the Thayer-Martin agar, to inhibit the possible growth of undesired bacteria or fungi, and maximize the growth of Neisseria species.

However, other Neisseria species, like N. meningitidis, have the same properties.

So the maltose fermentation test is done to differentiate the two.

The gist of it is that N. gonorrhoeae can’t ferment maltose, whereas N. meningitidis can.

To check for this, a pure sample from the culture of the suspected bacteria, is transferred to a sterile tube containing phenol red-maltose broth, which is then incubated at 36 degrees Celsius for 24 hours.


Neisseria gonorrhoeae is a gram-negative diplococcus, non-spore-forming, both oxidase and catalase-positive bacteria, which is known to cause a sexually transmitted infection (STI) called gonorrhea.

Gonorrhea manifests as urethritis in males and vaginitis and cervicitis in females, and if left untreated, it can progress to gonococcemia, and cause complications like gonococcal sepsis, septic arthritis, and endocarditis. Gonorrhea is diagnosed through a laboratory test of a vaginal or urethral swab, and is treated with antibiotics.


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