Lecture 5: Aerobic Gram Negative Cocci

(—) is part of normal flora of upper respiratory tract, but (—) is NEVER a normal flora organism

Neisseria; N. gonorrhoeae

• Kidney/coffee bean-shaped, GN diplococci or coccobacilli**

• Catalase +

• Oxidase + **

• Nonmotile

• Nitrate -

• Fastidious: Grow best in 5-10% CO2 at 37C **

Neisseria spp.

• Kidney/coffee bean-shaped, rod-shaped**

• Catalase +

• Oxidase + **

• Nonmotile

• Nitrate -

• Fastidious: Grow best in 5-10% CO2 at 37C **

Neisseria elongate

• Kidney/coffee bean-shaped, GN diplococci or coccobacilli**

• Catalase +

• Oxidase + **

• Nonmotile

• Nitrate -

• Fastidious: Grow best in 5-10% CO2 at 37C **

• Requires enriched media: CHOC (bc others grow on BAP)

N. gonorrhoeae

• Gram-negative diplococci**; often appears. Intracellular on gram stains (look within PMNs)

• Humans are only host

• Fastidious; does not survive long outside of host

• Sources: Urethra, cervix, anal canal, oropharynx, skin lesions, joints, blood

N. gonorrhoeae

Diagnostic tests for N. gonorrhoeae (4)

• Male urethral specimen w/ intracellular GN diplococci

• Female urethral specimen made on culture results

• Rectal specimens

• Pharyngeal specimens

N. gonorrhoeae will not grow on (—) **

SBA (sheep blood agar)

The performance of (—4—) with respect to overall sensitivity, specificity, and ease of specimen transport is better than any other tests available for the diagnosis of chlamydial and gonococcal infections

Nuclei acid amplification tests (NAATs)

Laboratories should use NAATs to detect chlamydia and gonorrhoeae EXCEPT in cases of (—3—)** involving boys and rectal and oropharyngeal infections in prepubescent girls and when evaluating a (—4—)**, in which case culture and susceptibility testing might be required

1) Child sexual assault

2) Potential gonorrhoeae treatment failure

• Causative agent: N. gonorrhoeae

• Males: Acute urethritis (inflammation of urethra)

• Females: Cervicitis and Pelvic inflammatory disease (PID)

• Neonates: Infected during vaginal delivery → gonococcal ophthalmia neonatorum

Gonorrhea

For medicolegal cases (ex. Suspected child abuse): (—) confirmatory tests should be used and should be different methodologies, such as… (4)

1) 2

1) RNA Probe

2) Carbohydrate utilization

3) Chromogenic substrate analysis

4) Immunologic/ELISA

Gonorrheal endocarditis:

Bacteria have spread and colonized the heart’s endocardium → inflammation

Gonorrheal meningitis:

When bacteria colonize the membranes that surround the brain (meninges)

Gonorrheal arthritis:

Infection w/in the joints

Pharyngeal gonorrhea:

Colonization of the anus

Disseminated gonococcal infection (DGI):

• Untreated infections may result in the bacteria entering the bloodstream → distributed throughout the body

• Usual sx: Septic arthritis and skin lesions, although numerous parts of the body can become infected

PID can lead to…

Sterility

Neonatal neonatorum:

Severe conjunctivitis leading to blindness

• Meningococcus

• Serogroups: A, B, C, Y, and W135 **

• Possibly part of normal flora of upper respiratory tract - spread through respiratory droplets

Neisseria meningitis is

Appropriate specimens for Neisseria cultures (4)

1) CSF

2) Blood

3) Petechial aspirates

4) Nasopharyngeal swabs

Why should you get Neisseria spp. to the lab quickly?

They are harmed by drying and extreme temperatures

Neisseria cultures and incubation

• Growth on BAP**, CHOC, and selective gonococcal media

• Incubate: Increased CO2 and humidity (like N. gonorrhoeae

Direct detection** of Neisseria spp:

Gram stain specimens (examined for intra-and-extracellular GN diplococci)

Latex agglutination and coagglutination antigen detection tests for (—2—) and is found in (—3—) specimens

1) Meningococcal antigens

2) CSF, Urine, Serum

Normal flora of upper respiratory tract, but can cause:

• Respiratory tract infections

• Bacteremia

• Endocarditis

• Otitis media

• Sinusitis

Moraxella catarrhalis

• Grows on BAP, CHOC, and selective gonococcal media (“hockey puck” or “scoots” **)

• Gram stain: GNC

• Catalase, oxidase, DNAse, nitrate, and butyrate esterase +

Moraxella catarrhalis

Carbohydrates utilization for N. gonorrhoeae

Glucose +

Carbohydrates utilization for N. meningitidis

Glucose and maltose +

Carbohydrate utilization for N. lactima

Glucose, maltose, and lactose +

Carbohydrate utilization for M. catarrhalis

None

Additional Testing for Neisseria spp. (3)

• Cystine trypticase agar (CTA)

• Rapid carbohydrate test

• Chromogenic substrate tests (detects enzymes)

Enzymes analyzed for Neisseria spp. in Chromogenic substrate tests (3)

1) Beta galactosidase

2) Gamma-glutamylaminopeptidase

3) Hydroxyprothylaminopeptidase

• Beta-galactosidase: -

• Gamma-glutamylaminopeptidase: -

• Hydroxyprothylaminopeptidase: + **

N. gonorrhoeae

• Beta-galactosidase: -

• Gamma-glutamylaminopeptidase: + **

• Hydroxyprothylaminopeptidase: -

N. meningitidis

• Beta-galactosidase: + **

• Gamma-glutamylaminopeptidase: -

• Hydroxyprothylaminopeptidase: +**

N. lactamica

• Beta-galactosidase: -

• Gamma-glutamylaminopeptidase: -

• Hydroxyprothylaminopeptidase: -

M. catarrhalis