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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 (-)
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