Neisseria spp. & Moraxella

Question 1

What are the general characteristics of pathogenic Neisseria species?

Answer 1

Aerobic, Gram-negative diplococci
* Oxidase-and catalase-positive
* Capnophilic organisms
* Exist as normal flora in upper respiratory and urogenital tracts

Question 2

Which species are considered primary pathogens among Neisseria?

Answer 2

N. gonorrhoeae and N. meningitidis

N. gonorrhoeae is always pathogenic, while N. meningitidis may be a commensal inhabitant

Question 3

What is the morphology of Neisseria gonorrhoeae?

Answer 3

Gram-negative cocci, often found as diplococci

Commonly referred to as ‘Gonococcus’

Question 4

How is Neisseria gonorrhoeae primarily spread?

Answer 4

By sexual contact

Question 5

What complications can arise from Neisseria gonorrhoeae infections in males?

Answer 5

Epididymitis, urethral stricture, prostatitis

Question 6

What percentage of women with gonorrhea are asymptomatic?

Answer 6

Up to 50%

Question 7

What are common symptoms of gonorrhea in females?

Answer 7

Burning on urination, vaginal discharge, vaginal bleeding, fever, abdominal pain

Question 8

What is disseminated gonococcal disease and who is it most commonly seen in?

Answer 8

Less than 1% of infections; usually seen in women

Question 9

What are the preferred clinical specimens for diagnosing Neisseria gonorrhoeae in males and females?

Answer 9

Urethra in males and cervix in females

Question 10

What medium should be used for transporting inoculated swabs of Neisseria gonorrhoeae?

Answer 10

Amies medium with charcoal

Question 11

What is the correlation percentage of Gram stain results with culture results in males with discharge?

Answer 11

95%

Question 12

What are the characteristics of Neisseria gonorrhoeae when viewed under a microscope?

Answer 12

Extracellular or intracellular Gram-negative diplococci

Question 13

What is the incubation period for cultures of Neisseria gonorrhoeae?

Answer 13

Cultures should be held for 72 hours, with colonies appearing after 24-48 hours

Question 14

What type of media is required for culturing Neisseria gonorrhoeae?

Answer 14

Selective media that reduces contaminating organisms
* Examples: Thayer-Martin, Modified Thayer-Martin, Martin-Lewis

Question 15

What is the purpose of the oxidase test in identifying Neisseria gonorrhoeae?

Answer 15

To detect the presence of cytochrome oxidase

Question 16

Fill in the blank: Neisseria gonorrhoeae is the second most commonly reported sexually transmitted disease after _______.

Answer 16

[chlamydia]

Question 17

True or False: Neisseria meningitidis is always pathogenic.

Answer 17

False

Question 18

What is the clinical significance of the pili in Neisseria gonorrhoeae?

Answer 18

Responsible for evading phagocytosis and exchange of genetic material

Question 19

What are the primary sites of gonorrhea infection?

Answer 19

Urethra, endocervix, anal canal, pharynx, conjunctiva

Question 20

What is the maximum time colonies can be held before identification?

Answer 20

72 hrs.

Colonies can appear after 24-48 hrs.

Question 21

What is the presumptive identification for Neisseria gonorrhoeae?

Answer 21

Neisseria gonorrhoeae

Question 22

What test must be completed on all isolates of Neisseria?

Answer 22

Oxidase test

Question 23

What does the oxidase test detect?

Answer 23

Presence of cytochrome oxidase

Question 24

What is the method used to perform the oxidase test?

Answer 24

Filter paper method or directly on agar medium

Question 25

What indicates a positive reaction in the oxidase test using filter paper?

Answer 25

Purple colour

Question 26

What is the oxidase reagent used in the oxidase test?

Answer 26

1% dimethyl-p-phenylene-diamine-dihydrochloride

Question 27

What is the color change indicating a positive reaction when the oxidase reagent is placed directly on colonies?

Answer 27

Pink colour that turns to black

Question 28

What is required for a definitive diagnosis of oxidase-positive Gram-negative diplococci?

Answer 28

Further testing must be completed

Question 29

Name three oxidase-positive Gram-negative diplococci that can grow on gonococcal selective media.

Answer 29

* Moraxella spp. * Neisseria meningitidis * N. cinerea

Question 30

What is the traditional method for identifying Neisseria species?

Answer 30

Carbohydrate utilization method

Question 31

What does a positive result in the carbohydrate utilization test indicate for Neisseria gonorrhoeae?

Answer 31

Acid produced only in the glucose tube

Question 32

What are the carbohydrate utilization test results for Neisseria species?

Answer 32

* Glucose only – N. gonorrhoeae * Glucose and maltose – N. meningitidis * Asaccharolytic – M. catarrhalis

Question 33

What is the incubation period for the carbohydrate utilization test?

Answer 33

24-72 hours

Question 34

What is the rapid carbohydrate test used for?

Answer 34

Tests for preexisting enzymes for carbohydrate utilization instead of bacterial growth

Question 35

What is the superoxyl test used to differentiate?

Answer 35

N. gonorrhoeae produces vigorous and immediate bubbling

Question 36

What are the immunologic methods for identifying N. gonorrhoeae?

Answer 36

Coagglutination or fluorescent antibody testing

Question 37

What is the significance of the encapsulated strains A, B, C, Y, and W135 of Neisseria meningitidis?

Answer 37

Most often associated with epidemics

Question 38

What are the virulence factors of Neisseria meningitidis?

Answer 38

* Pili * Capsule * Endotoxin production * IgA protease

Question 39

How is bacterial meningitis transmitted?

Answer 39

By respiratory droplets or oral secretions

Question 40

What are common symptoms of bacterial meningitis?

Answer 40

* Fever * Headache * Stiff neck * Nausea * Vomiting

Question 41

What is the mortality rate associated with meningococcemia?

Answer 41

25%

Question 42

What specimens are collected for culture of Neisseria meningitidis?

Answer 42

* CSF * Blood * Nasopharyngeal swabs * Aspirates

Question 43

What agar supports the culture of Neisseria meningitidis?

Answer 43

Chocolate agar and sheep blood agar

Question 44

What is a distinguishing feature of Moraxella catarrhalis in laboratory diagnosis?

Answer 44

Produces beta-lactamase

Question 45

What type of colonies does Moraxella catarrhalis produce on culture?

Answer 45

Smooth, opaque, gray to white colonies

Question 46

How is Moraxella catarrhalis differentiated from Neisseria species?

Answer 46

Positive DNase and butyrate esterase reactions