midterms

1. Gram Negative Cocci
Neisseria gonorrhea
Neisseria meningitidis
• Common pathogen in man
• 70% they are related with DNA homology

2. Genera and Species
Neisseria
- N. gonorrheae= Gonococci
Encapsulated and have plasmids
- N. meningitidis= Meningococci
Capsulated and don’t have plasmids
Other Neisseria spp. (rare cause of infection)
-N. cinerea N. sicca N. flavescens
-N. lactamica N. subflava N. elongate(bacillus, - catalase)
-N. polysarccharea N.mucosa

3. Genera and Species
Moraxella catarrhalis
- Formerly Branhamella Neisseria catarrhalis
Veillonella
- GIT, GUT and RT
Family Neisseriaceae Genera:
• Neisseria- prevalent pathogen
• Kingella
• Cikenella
• Simonsiella
• Alysiella

4. Morphology and Identification
A. Typical Neisseria
 Gram negative diplococci
 Non-motile and non-spore forming
Approximately 0.8 um in diameter
Individual cocci is KIDNEY/COFFEE BEAN SHAPED (except
elongate)
 In pairs, the flat or concave sides are adjacent
Cytochrome oxidase and catalase POSITIVE
 Non pathogenic is the normal flora of the URT
Obligate aerobe at the same time they need O₂ (that’s why
catalase +)

5. Morphology and Identification
B. Culture (BAP/CAP)
 On enriched medium in 48 to 72 hours= capnophilic
 Gonococci/Meningococci
- convex, glistening, elevated, mucoid colonies 1-5 mm in
diameter
- Transparent or opaque, non-pigmented, non-hemolytic
- Pathogenic Neisseria
- Very fastidious which requires BAP and CAP (iron, hemin,
coenzyme 1)
- Gonococci need cysteine for growth

6. Morphology and Identification
B.Culture
 N. flavescens, N. cinerea, N. subflava, N.
lactamica may have YELLOW pigmentation
N. sicca produces opaque, brittle, wrinkled
colonies
Moraxella catarrhalis produces nonpigmented or
PINKISH GRAY opaque colonies

7. Morphology and Identification
C. Growth/Biochemical Characteristics
Neisseria grow best under aerobic conditions
Some grow best in anaerobic environment
Most oxidize carbohydrates with acid but no gas
Produce oxidase and give (+) oxidase reaction
Atmospheric requirement: 5% CO₂ in CANDLE JAR

8. Morphology and Identification
C. Growth/Biochemical Characteristics
• Modified Thayer Martin, Lewis Martin, GC-Lect, New York City
• MTM: vancomycin, colistin, nystatin, trimethoprim
• ML: anisomycin and trimethoprim
• Contain antimicrobial drugs
 vancomycin: inhibits gram positive bacteria (3 ug/mL)
 lincomycin: alternative for vancomycin
 colistin: inhibits gram negative bacteria
 amphotericin B
 nystatin: inhibits fungi
 anisomycin: used in LM instead of nystatin
 trimethoprim: inhibits swarming of proteus

9. Growth on MTM, ML, NYC
• Positive growth
- N. gonorrheae
- N. meningitidis
- N. lactamica
• Variable growth
- N. cinerea
- N. polysaccahareae
• Negative growth
- N. sicca -N. flavescens
- N. subflava -N. elongate
- N. mucosa -Moraxella catarrhalis

10. Morphology and Identification
C. Growth/Biochemical Characteristics
 Catalase positive
 Oxidase test: a key test for ID
DARK PURPLE
Rapid test- filter paper soaked with tetra-methyl-
paraphenylene diamine hydrochloride
 Most oxidize carbohydrates producing acid but not gas
 CARBOHYDRATE PATTERNS means of distinguishing
them
Cysteine Trypticase Agar (CTA) add sugars:
Glucose, Maltose, Lactose, Sucrose

11. Results CTA Carbohydrates
SPECIES OXIDASE GLUCOSE MALTOSE LACTOSE SUCROSE
N.
Gonorrheae
+ + - - -
N.
Meningitidis
+ + + - -
N.
Lactamica
+ + + + -
N.
Catarrhalis
(DNAse
positive)
+ - - - -

12. Morphology and Identification
C. Growth/Biochemical Characteristics
 Inhibited by toxic constituents (Fatty acids &
Salts)
Rapidly killed by drying, sunlight, moist heat, and
many disinfectants
Produce autolytic enzymes results in:
Rapid swelling
Lysis in vitro at 25⁰C and at an alkaline or high
pH