-
What does the acronym HACEK stand for and why is it used?
- Haemophilus (especially H. aphrophilus)
- Actinobacillus actinomycetemcomitans
- Cardiobacterium hominis
- Eikenella corrodens
- Kingella
- Members of this group are fastidious and important causes of endocarditis
-
What are the special growth requirements?
- Hemin (X Factor) - released from hemoglobin
- NAD (V Factor) - heat-labile compound
-
Identify the specific growth requirements and hemolysis for each Haemophilis species
-
Why can't Haemophilis grow on SBA but what can it do on SBA?
- It contains NADase in the agar
- Haemophilus species will grow around Staph aureus, causing satellitism
-
What are the tests and results of Haemophilis?
- Nonmotile
- Catalase - POS
- Oxidase - POS
-
What are the serotypes and biotypes of Haemophilus influenzae?
- 6 capsular serotypes - a-f
- 8 biotypes - I-VIII
-
What bacteria is associated with:
Major cause of meningitis in children
Serotypes other than b cause resipiratory tract infections, acute sinustitis, chronic bronchilits, and pneumonia
Otitis media with effusion and sinusitis are often caused by nontypeable strains, those lacking a capsule
Requires X and V
ALA and Hemolysis NEG
H. influenzae
-
What should H. influenzae be tested for?
Beta-lactamase
-
What bacteria is associated with:
Rarely a respiratory pathogen
Requires V
ALA POS
Hemolysis NEG
H. parainfluenzae
-
What bacteria is associated with:
Pink eye (Conjunctivitis followed by invasive disease known as Brazilian purpuric fever)
Sucrose POS
Requires X and V
ALA and hemolysis NEG
Indole NEG
Urease POS
Ornithine decarboxylase NEG
Haemophilus aegyptius
-
What bacteria is associated with:
Genital ulcers (a STD)
Chancroids and buboes (swollen lymph nodes)
Requires X
ALA and Hemolysis NEG
Haemophilus ducreyi
-
What genera is included with the family Neisseriaceae?
- Neisseria
- Eikenella
- Kingella
- Simmonsiella
-
What are the tests and results performed to identify the family Neisseriaceae?
- Gram negative diplococci or coccobacilli
- Oxidase - POS
- Fastidious
- Grows best in 5-10% CO2 at 37 degrees celcius
- They cannot tolerate cold - media must be at room temp before plating
-
Where is Neisseria gonorrhoeae found?
- Only in humans
- Urethra
- Cervix
- Anal canal
- Oropharynx
- Skin lesions
- Joints
- Blood
-
In MALES, what are the clinical conditions associated with Neisseria gonorrhoeae?
- Acute urethritis (pus containing urethral discharge)
- Dysuria
- Prostatitis
- Epididymitis
-
In FEMALES, what are the clinical conditions associated with Neisseria gonorrhoeae?
- Urethral infections
- Cervicitis
- Infections can be asymptomatic or produce cervical discharge, fever, acute pain, and dysuria
- Pelvic inflammatory disease (PID)
- Gonococcal arthritis
- Salpingitis
- Endometritis
- Peritonitis
-
In NEONATES, what are the clinical conditions associated with Neiserria gonorrhoeae?
- Gonococcal ophthalmia neonatorum (severe conjunctivitis leading to blindness)
- To prevent conjunctivitis, antimicrobial (erythromycin) drops are given to all infants at birth
-
What bacteria:
Gram Stain - Intracellular in neutrophils
Requires enriched media such as chocolate (Does NOT grow on SBA), modified Thayer-Martin, Martin-Lewis, New York City, and CG-Lect agars
Superoxol - POS
Catalase - POS
Oxidase - POS
Glucose - POS
Maltose, Lactose, Sucrose - NEG
DNase - NEG
Nitrate - NEG
Many strains are positive for beta-lactamase production
Neisseria gonorrhoeae
-
What clinical conditions are associated with Neisseria meningitidis?
- Meningococcal meningitis
- Meningococcemia, leading to disseminated intravascular coagulation
- Waterhouse-Friderichsen syndrome
-
What specimens is Neisseria meningitidis found in?
- CSF
- Sputum
- Blood
- Nasopharyngeal swab
-
What bacteria is:
Catalase - POS
Oxidase - POS
Glucose and Maltose - POS
DNase - NEG
Nitrate - NEG
Neisseria meningitidis
-
What clinical conditions are Kingella associated with?
- K. kingae - infections of bones and joints in children (immunocompromised)
- K. dentifricans - endocarditis
-
What is a key test to differentiate Kingella dentrificans from Neisseria gonorrhoeae?
K. dentrificans will reduce nitrates
-
What bacteria:
Associated with Otitis media, Sinusitis, Respiratory tract infections
Catalase - POS
Oxidase - POS
DNase - POS
Nitrate - POS
Butyrate esterase - POS
Asaccharolytic (unable to breakdown carbs for energy) - all carb tests are NEG
Moraxella catarrhalis
-
How many toxins does staph aureus produce and name one
- 6 different types of enterotoxin
- Toxic Shock Syndrome Toxin-1 (TSST-1)
-
What bacteria:
Associated with Food poisoning (via enterotoxin), Pneumonia, Osteomyelitis, Endocarditis, Wounds, scalded skin syndrome
Gram positive cocci in clusters
Beta hemolytic
Catalase and Coagulase positive
PYR (pyrrolidonyl-alpha-naphthylamide) and ornithine NEG
Can tolerate high salt concentration (7.5%) of mannitol salt agar (MSA)
Ferments mannitol, producing yellow colonies on MSA
Staph aureus
-
What makes Staph aureus penicillin resistant?
Beta-lactamase production
-
What makes Staph aureus resistant to Methicillin?
Resistant to Beta-lactam antibiotics because of production of altered penicillin-binding proteins
-
What makes Staph aureus resistant to Vancomycin?
- Resistance due to VanA operon that alters the target of vancomycin in the cell wall
- VISA (Vancomycin Intermediate Staph aureus) occurs following overproduction of the target
-
What bacteria:
Mostly skin flora and being nonpathogenic, Can cause disease in immunosuppressed and neutropenic patients with UTIs from catheters and shunts
Gram positive cocci in clusters
Nonhemolytic
Catalase positive
Coagulase negative
Coagulase-negative staph
-
What bacteria:
Most common species of coagulase negative staph
Novobiocin susceptible
Staph epidermidis
-
What bacteria:
Significant only in UTI's in women
Novobiocin resistant
Staph saprophyticus
-
What bacteria:
Frequent cause of endocarditis
Ferments mannitol
PYR positive
Staph lugdunensis
-
Describe Micrococcus
- Considered normal flora of skin and mucous membrane - rarely cause infections
- Modified oxidase test Positive
-
Describe the general characteristics of Streptococcaceae
- Catalase negative
- Gram positive cocci in pairs or chains
- Alpha, beta, or nonhemolytic (gamma)
- Lancefield grouping is based on a cell wall antigen
-
What is another name for Group A Strep?
Strep pyogenes
-
What bacteria:
Associated with: Strep throat (pharyngitis), Impetigo, Cellulitis, Scarlet fever, Pneumonia, Otitis media (middle ear infections), Necrotizing faciitis
Secondary effects of Rheumatic fever and Post-Streptococcal Glomerulonephritis
Bacitracin (A disk) susceptible
PYR positive
Often use latex agglutination
Group A Strep (Strep pyogenes)
-
Name some of the virulence factors of Group A Strep (Strep pyogenes)
- Cell wall M protein inhibits phagocytosis
- Streptococcal pyrogenic extoxin (Spe A, B, C, F), formerly known as erythrogenic toxin, causes the rash seen in scarlet fever and act as superantigens to interact with macrophages and T helper cells to stimulate massive release of cytokines, and are associated is toxic schock syndrome (STSS)
- Streptokinase dissolves clots
- Hyaluronic acid capsule inhibits phagocytosis
- Streptolysin O and streptolysin S lyse erythrocytes, platelets, and neutrophils
- Hyaluronidase hydrolyzes hyaluronic acid, and interstitial barrier, facilitating spread of infection (strains that produce a hyaluronic acid capsule will not produce hyaluronidase)
-
What Lancefield groups do Streptococcus dysgalactiae - subspecies equismilis express
Lancefield group C or G antigens
-
What clinical spectrum of diseases do Streptococcus dysgalactiae - subspecies equismilis resemble?
- Pharyngitis
- Skin infections
- Necrotizing fasciitis
- STSS
- Endocarditis
- Glomerulonephritis
- Acute rheumatic fever
-
What bacteria:
Neonates - sepsis and meningitis
Mothers - postpartum fever, osteomyelitis, wound infections, endocarditis, pneumonia, pyelonephritis (in immunocompromised patients)
Can show beta hemolysis or gamma (nonhemolytic)
CAMP test - POS
Hippurate Hydrolysis - POS
PYR - NEG
Resistant to bacitracin
Group B Streptococcus (Strep agalactiae)
-
What bacteria:
Associated with Wound infections, UTIs, Abdominal abcesses, Isolation of Group D, Strep in blood cultures are an indicator of colon cancer
Bile-esculin positive
Negative for growth in 6.5% NaCL
PYR negative
Group D Streptococcus
-
What bacteria:
Bacterial endocarditis in people with damaged heart valves
Wound infections
Brain abcesses
May enter the blood after dental procedures
Optochin (P disc) resistant
Insoluble in bile
Does not grow on bile-esculin medium
Viridans streptococci
-
What bacteria:
Associated with Lobar pneumonia (in elderly and alcoholics), Otitis media (infants and children), Meningitis (vaccine has reduced this from occurring), Community-acquired bacterial pneumonia (sputum are often rust colored)
Gram positive diplococci that are lancet or bullet shaped
Alpha hemolytic
Optochin (O or P disc) Sensitive
Bile (10% sodium deoxycholate) soluble
Streptococcus pneumoniae
-
What are the most commonly encountered species of Enterococcus?
-
What are the tests and results to identify Enterococcus?
- Bile esculin - POS
- Positive for growth in 6.5% NaCl
- PYR - POS
- Express Lancefield group D antigen
- Can be alpha, beta, or gamma hemolytic
-
What causes Enterococcus to be vancomycin resistant (VRE)
Resistance is due to altered peptidoglycan cross-link target: D-Ala-D-Ala to D-Ala-D-Lac or D-Ala-D-Ser
-
What is the species that are the majority of VRE (Vancymycin resistant Enterococcus)?
E. faecium
-
What bacteria:
Associated with Endocarditis, Meningitis, Brain abcesses, Lung abcesses, Osteomyelitis
PYR - POS
LAP (leucine aminopeptidase) - POS
Bile esculin - NEG
Gamella
-
What bacteria:
Associatd with Osteomyelitis, Ventriculitis, Postsurgical endophthalmitis, Bacteremia in neonates
Vancomycin resistant
PYR - NEG
LAP - NEG
Catalase -NEG
Leuconostoc
-
What was formerly known as nutritionally variant streptococci?
- Abiotrophia
- Granulicatella
-
What bacteria:
Requires Vitamin B6 (pyridoxal or pyridoxamine) for growth
Associated with Endocarditis, Ophthalmic infections, Infections of the central nervous system (CNS)
- Abiotrophia and Granulicatella
- (Formerly known as nutritionally variant streptococci)
|
|
