HACEK GROUPHACEK GROUPGROUP 1GROUP 1

HACEK GROUP• H-aemophilus spp.,

– Aggregatibacter aphrophilus– H. paraphrophilus

• Aggregatibacter actinomycetemcomitans

• Cardiobacterium hominis

• Eikenella corodens

• Kingella spp.

GENERAL CHARACTERISTICS

• Gram (-) rods• Capnophilic• Non-motile• Fastidious• More dysgonic- slower or poorer growing

(Except Haemophilus spp.)• Endocarditis-involved in heart valves• Non/fermentative• Normal biota of the oral cavity• Opportunistic and required a compromised

host

Aggregatibacter aphrophilus• Foaming lover or needing high [CO2]

• Most prevalent species in the group producing endocarditis

• H.aphrophilus and H.paraphrophilus have been recently reclassified as a single specie

• Contains V factor in/dependent– Clinical features

• Fever• Heart murmur• Congestive heart failure• Embolism

Cultural characteristics Culture Media

• Raised, convex, granular and yellowish

• Small cocobacillus

• Ferments glucose, maltose, sucrose and lactose

• Trypticase Soy Agar

• Chocolate Agar

Aggregatibacter actinocetemcomitans

• Formerly known as Actinobacillus• Small bacilli to coccoid gram-negative bacilli• 6 serotypes (a-f)

– a,b & c are the most common• Normal oral microbiota • Subacute bacterial endocarditis

Virulence factors: Collagenase- toxic to polymorphonuclear cells and Leukotoxin monocytes

Cultural Characteristics

• Ferments glucose, maltose, manitol & xylose

• Catalase +• “Star shape with 4-6

points” in the center of the colonies

• Very small cocobacillus in Gram stain

• Small colonies that adhere to agar

Culture media: BHI Trypticase soy agar

DISEASE ACQUIRED

– MOT• ENTERS IN DEEPER TISSUE BY MINOR

TRAUMA TO MOUTH, SUCH AS DURING DENTAL PROCEDURES

– DISEASE• Causative agent of SUBACUTE BACTERIAL

ENDOCARDITIS with an insidious and protracted presentation, usually treated by penicillin

• PERIODONTITIS- “Inflammation around the tooth and gum”

Sensitivity to penicillinIsolates are susceptible to: Aminoglycosides Cephalosporins Quinolones Chloramphenicol Tetracycline

Resistance to vancomycin and erythromycin

Cardiobacterium spp.

HAVE TWO SPECIESCardiobacterium hominisCardiobacterium valvarum

General Characteristic

PleomorphicGram-negative bacillusNormal microbiota of the noseMouthThroatDISEASE acquired is ENDOCARDITIS

Gram stains of the bacilli often show false gram-positive reactions in the parts of the cells.

The organisms tend to form rosettes,swellings,long filaments or in yeast extract, stick like structures.

They grow slowly on SBS and CHOC agar but not at all on MAC agar.

ANTIMICROBIAL SUSCEPTIBILITY

• Sensitive to B-lactams, Chloramphenicol & tetracycline

• Therapy: penicillin and an aminoglycoside

Eikenella corrodens

• Gram-negative cocobacilli• CO2 with hemin• Oxidase positive• Asacchrolytic• Catalize negative• Chloride bleach odor

• Normal biota oral and bowel cavity• Colony: Pits the agar• Broth medium: adhere to the side medium

produce granules

INFECTIONS ASSOCIATED

• Clenched fist wounds due to trauma, human bites or fights

• Meningitis, empyema (collection of pus in space between the lungs), pneumonia, osteomyelitis, arthiritis, and postoperative tissue infection

• In drug addicts produce cellulitis

Antimicrobial susceptibility

• RESISTANT TO clindamycin and aminoglycosides

• IN-VITRO SENSITIVITY to penicillin, ampicillin, cefoxitin, chloramphenicol, carbenicilin, imipenem, cephalosphorins, & trimethoprim-sulfamethoxazole

KINGELLA

General Characteristic• Cocobacilli “short bacilli with squared

ends that occur in pairs or short chain”• They tend to resist decolorization in the

gram staining Note: if the isolate does not pit the

agar as many strains do can resemble Neisseria gonorrhoeae.

• They are tend nutritionally fastidious • Fermenters of glucose and other sugar

with no gas • Oxidases positive • Catalase negative

• Cultural morphology– may grow on

Neisseria selective agar(Thayer Martin Medium)

– usually susceptible to most agents , including PENICILIN

• Infection–They colonize

the upper respiratory tract specially the tonsils

–Poor dental hygiene or oral surgery associated with infection

Consist of 3 spp.1. Kingella kingae -are recognized as an important

pathogen in the pediatric population. - weakly ferments glucose and maltose

but negative in sucrose -produces yellow brown pigments - Two types of colony morphology - spreading corroding colony or

smooth , - convex and ß-hemolytic colony

-The hemolysis may appear beneath the colony or in close proximity after24hrs.after 48hrs of incubation

-it is major gram negative bacterium isolated from denegrative joint and bone infection (osteoarthritis)

2. Kingella denitrificans-positive for glucose fermentation and nitrate reduction and might grow at 46°C

-Both catalase and superoxol are negative. -It is negative for -urease -indole esculin gelatin citrate -Does not grow on MAC agar -Two types of colonies morphology - smooth and convex type and Spreading

corroding type - This spp. is rarely isolated as a pathogen but

has been associated with bacteremia

3. Kingella oralis

newly described species in the human oral cavity

The mean percentage of K. oralis in total microbiota in the dental plaque ranged from 0.40% in the periodontally healthy group to 4.60% in localized juvenile periodontitis subjects. The organism was a significant species in a few periodontitis sites, constituting > 5% of the total microbiota.

Periodontitis-Most common disease because of HACEK bacteria

“inflammation around the tooth" - it is a serious gum infection that damages the soft tissue and bone that supports the tooth.

Organism catalase

oxidase

glucose

maltose

sucrose

lactose

Gram staining

Colony Morphology COMMENTS

A. Aphrophilus - V + + + +Small

coccobacillus

Raised, convex, granular, yellowish

A. actinomycetem

comitans

+ V + + - -Very small

coccobacillus

Small colonies that

adhere to agar

C. Hominis - + + + + -Straight bacillis, spindle, rosettes

Smooth, opaque,

adherent to agar

Indole (+)

Eikenella corrodens

- + - - - - Straight rods

Usually pits the agar

Smell like bleach

Ornithine (+)

Kingella kingae - + + + - - Coccoid to straight

bacili, chains and pairs

2 types: spreading & corroiding or

smooth & convex beta hemolysis

Nitrate (-)