Aerobic Gram Negative Cocci

Student LabDivision of Medical Technology

Jeanne Filbey, MT(ASCP)

General Characteristics• Normal flora of upper respiratory,

alimentary and genitourinary tracts • Gram stain: GNDC• Oxidase positive• Catalase positive• Non-motile

Aerobic GNDC

Neisseria gonorrhoeae• Fastidious• Temperature sensitive• Culture immediately• Transport media if delay

Aerobic GNDC

Specimen Gram Stain• Intracellular GNDC

Neisseria gonorrhoeae

Colony Morphology• Chocolate agar

• Thayer-Martinagar– Growth– Contains antibiotics

Neisseria gonorrhoeae

Identification• Carbohydrates

– Glucose pos– Maltose neg– Lactose neg– Sucrose neg

• DNase neg• Nitrate neg• Butyrate esterase neg

Neisseria gonorrhoeae

Pathogenesis• Port of entry• Progression of infection• Human to human transfer• Females asymptomatic

Neisseria gonorrhoeae

Gonorrhea• Male

– Acute urethritis, prostatitis and epididymitis if untreated

• Female– May be asymptomatic– Cervicitis --> pelvic inflammatory disease --

> scarring of fallopian tubes --> sterility, ectopic pregnancies

Neisseria gonorrhoeae

Other Infections• Disseminated gonococcal infection• Pharyngitis• Gonococcal ophthalmia neonatorum• Vulvovaginitis

Neisseria gonorrhoeae

Treatment• Antimicrobial testing

Neisseria gonorrhoeae

Neisseria meningitidis• Fastidious• Temperature sensitive• Culture immediately• Occasionally grows on SBA

Aerobic GNDC

Specimen Gram Stain• GNDC

Neisseria meningitidis

Colony Morphology• Chocolate agar

• Thayer-Martinagar– Growth

Neisseria meningitidis

Identification• Carbohydrates

– Glucose pos– Maltose pos– Lactose neg– Sucrose neg

• DNase neg• Nitrate neg• Butyrate esterase neg

Neisseria meningitidis

Pathogenesis• Meningitis• Septicemia• Septic arthritis• Endocarditis• Pneumonia• Urethritis• Asymptomatic nasopharyngeal carriers

Neisseria meningitidis

Neisseria lactamica• Normal flora

Aerobic GNDC

Colony Morphology• Chocolate agar

• Thayer-Martinagar– Growth

Neisseria lactamica

Identification• Carbohydrates

– Glucose pos– Maltose pos– Lactose pos– Sucrose neg

• DNase neg• Nitrate neg• Butyrate esterase neg

Neisseria lactamica

Moraxella (Branhamella) catarrhalis• Can be normal respiratory flora

Aerobic GNDC

Colony Morphology• Sheep blood agar• Chocolate agar• Thayer-Martin

agar– Growth

Moraxella (Branhamella) catarrhalis

Identification• Carbohydrates

– Glucose neg– Maltose neg– Lactose neg– Sucrose neg

• DNase pos• Nitrate pos• Butyrate esterase pos

Moraxella (Branhamella) catarrhalis

Pathogenesis• Acute bronchitis• Pneumonia• Meningitis• Seen in immunocompromised patients

(elderly)• Otitis media & maxillary sinusitis in kids• Most produce beta lactamase

Moraxella (Branhamella) catarrhalis

Summary• Specimen handling and processing• Growth characteristics• Identification• Clinical significance• Antimicrobial testing

Aerobic GNDC

Who am I?

Urethral gram stain Thayer Martin agar

Neisseria gonorrhoeae

Who am I?

CSF gram stain Chocolate agar

Neisseria meningitidis