HACEK orgs (fastidious GNR) and CSF cultures

Haemophilus general characteristics

Pleomorphic GN coccobacili

Usually oxidase and catalse pos

Need extra growth factors (X/V)

X factor

Hemin, available in intact and lysed RBCs

V factor

NAD, only available when RBCs are lysed

What does the prefix para mean for growth factors

Only require V factor

Satellitism

Haemophilus can get the required growth factors when next to a strongly beta hemolytic organism (like staph aureus)

Can Haemophilus be NF

Yes, often found in respiratory tract

Haemophilus influenzae infections and transmission

Mild to severe infections, from sinusitis and pneumonia to meningitis and sepsis

Transmitted via respiratory droplet

Haemophilus influenzae capsule

Virulence factor, can differentiate strains by serotyping capsule

Haemophilus influenzae vaccine

Serotype b was biggest cause of disease in the late 90s (Hib vaccine reduced rates)

Now most common infections are from non-typable Haemophilus

Epiglottitis (Haemophilus influenzae)

Rapid onset, acute inflammation that can lead to airway obstruction

Often treated based on clinical presentation, not culture

Haemophilus aegyptius

Causes acute contagious conjunctivitis, pediatric populations at risk

Brazilian purpuric fever (BPF)

Rare but serious infection caused by Haemophilus aegyptius

Conjunctivitis, vomiting, fever, rash, sepsis

Haemophilus ducreyi

Causes genital ulcer disease, an STI, termed chancroid (soft chancre)

Not normal flora

Haemophilus ducreyi gram stain

Pleomorphic GNR, appear as school of fish or railroad tracks

What do you always plate on for Haemophilus species

Chocolate agar (has X and V factor)

Haemophilus influenzae colony morph

Growth on choc is translucent, tan, moist

Distinct mousy or bleach odor

No growth on BAP or MAC

Haemophilus influenzae gram stain

Pleomorphic GN coccobacili

Length varies, can find intracellularly

Haemophilus influenzae on quad agar

Growth in quadrants 3 and 4 (needs X and V factor)

Porphyrin test

Determines if an organism needs X factor

Substrate ALA in the plates is converted to porphyrins or porphobilinogen

Negative for H. influenzae (meaning X factor dependent)

HACEK group general characteristics

Normal flora of oropharynx, opportunistic pathogens that can cause endocarditis

Slow growing, capnophilic

Aggregatibacter aphrophilus general characteristics

Found in dental plaque, colonies are convex, granular and yellow

Most prevalent of the HACEK group

Aggregatibacter actinomycetemcomitans

Oral flora that causes periodontitis

Colonies are distinct star shape and prefer increased CO2

Does not require X or V factor

Cardiobacterium hominis

Normal flora of oral cavity. Requires CO2 for growth, may see pitting on agar

Gram stain: GNB that can stain false GP and form rosettes

Eikenella corrodens

Normal flora of oral cavity and GI tract. GN coccobacili

Wound infections from bites

Growth on BAP and Choc that spreads a little. May pit agar and have bleach like odor

Kingella general characteristics

Normal flora of URT, especially tonsils

Gram stain: GN coccobacili with square ends

Can grow on Neisseria selective agar (Kingella is usually catalase neg, Neisseria catalse pos)

Causes of meningitis

Bacterial, Viral, fungal, spirochetes, other (Naegleria or Malaria)

Bacterial meningitis causes

Listeria monocytogenes, strep agalactiae, Haemophilus influenzae, Neisseria meningitidis, Strep pneumo

How many CSF tubes are collected and where do they go

1 and 4 go to heme, 2 is chem testing, and 3 is micro

What happens to glucose and protein with bacterial meningitis

Glucose decreases and protein increases

Do you quantitate cytospun CSF

No, just report any bacteria seen

What would you plate with a CSF specimen

BAP and choc agar, incubate at 35C for 24 hours