WK 4 - micro, staph, strep Flashcards
MICROCOCCACEAE
(Type of pathogen)
- Members of gram-positive cocci, aerobic or facultative
anaerobes - Catalase (enzyme required to neutralize the toxic forms of
oxygen) positive (except Stomatococcus)
significant members of micrococcaceaea
Members that are
significant among them are the: Staphylococcus,
Micrococcus, Stomatococcus
in clusters, bunch of grapes; Spherical bacteria that are
clustered together
Staphylococcus
are micrococcacea catalse positive or nefgative? what about its members?
Catalase (enzyme required to neutralize the toxic forms of
oxygen) positive (except Stomatococcus)
staphylococcus
- Catalse positive
- Non-motile
- Facultative anaerobes
staphyklococcus are found where
normal inhabitants of skin and mucous membranes sila (anterior nares’ main residence)
Commonly cause human infections - because of the wide
variety of virulence factors that they can produce
staphylococcus
Species are differentiated by coagulase test,
staphylococcus S, the most
important being the coagulase positive S. aureus
in staphylococcus, Some animal species produce coagulase but are rarely
isolated from human samples
(ex. S. hyicus and S. intermidius
micrococcus type of pathogen
- Opportunistic pathogens found only in
immunocompromised patients
of low pathogenic significance - May be isolated as a contaminant or as part of the normal microbiota
hen they grow, they give out a yellowish color
and they’re usually seen in tetrads
micrococcus luteus
stomatococcus
- Part of the normal oral microbiota
- Rarely isolated from infections
- Colonies strongly adhere to the agar surface
There is only one species of Stomatococcus
There is only one species of Stomatococcus which is now
placed under Rothia genus.
o Rothia mucilaginosa is mostly associated with
prosthetic device infections
Staphylococcuus aureus infection
- skin and wound infections
- food posioning
- scalded skin syndrome or ritter’s disease
- TSS
- others : c. pneumonia, ostemyelitis, wound, abcess, skin infection
food posion in staphylococcus is due to
– Stapylococcal enterotoxins A and D
(heat-stable toxins pre-formed in food)
ritter’s disease is caused by
caused by
exfoliative/epidermolytic toxin and occur in newborns, and
in adults having chronic renal failure or are
immunocompromised
STAPHYLOCOCCUS
MORTALITY RATE OF SCALDED SKIN SYNDROME OR RITTER’S DISEASE
Mortality rate: Low in newborn, High in adults
having chronic renal failure for
immunocompromised
TOXIC SHOCK SYNDROM IS CAUSED BY6
S. aureus that
produces enterotoxin F (TSST-1)
There is a strong association within the use of
tampons
tss
There is a strong association within the use of
tampons and TSS and this can occur in both
sexes.
other infections of staphylococcus
o Staphylococcal pneumonia secondary to
influenza can occur
o Osteomyelitis can occur secondary to bacteremia
o Most outstanding association of S. aureus to
infection: Wound, abscesses and other skin
infections
o When you culture a wound specimen, abscess
and exudates and other purulent discharges you
will appreciate that at least 80% of those
conditions or samples will lead to or isolate a
staphylococcus aureus
virulence factors of staphylococcus
- coagulase
- protein a
- hemolysins
- exoenzymes
a bacterial enzyme that brings
about the coagulation of blood or plasma
coagulase
– a cellular component in the cell wall
that helps the bacteria to avoid phagocytosis
because of its ability to bind and neutralize IgG
protein a
yse RBCs, damage platelets and
even macrophages
hemolysin a
sphingomyelinase primarily C
hemolysin b
exotoxin little to polymorphonuclear
cells associated to Panton-Valentin
leukocydin
hemolysin y
east toxic among these cytolytic
toxins
hemolysin δ
allows the spread of
infection, by removing the cement that
glues connective tissues together, such
as the hyaluronic acid
Dehyaluronidase
facilitates S. aureus to
colonization of skin surface
lipase
exoenzymes found in staphylococcus
dehyaluronidase and lipase
methods of id in staphylococcus
- phenotypic = itusura
- immunological = serological analysis used in lab kits and serotyping
- genotypic = genetic techniques used to
in the lab, we will be just confined in just identifying S.
aureus into mostly
phenotypic means and a little of
immunological means.
what is positive reaction in coagulase test in staphylococcus
clot formed at the bottom of
the plasma tube indicates a positive reaction
cultural techniques fior staphylococcus
s – culturing on blood agar plates,
growing as round, smooth, white (sometimes yellowish)
and beta-hemolytic (completely lyses RBCs)
o You will see clearing at the bottom of the plate
due to RBC lyses
o 2 types in Blood agar plates: As white colonies
that are medium in size or, yellow or gold
colonies that are medium in size
o Beta-hemolytic colonies are best appreciated in
Sheep’s Blood Agar
catalse test for staphy
▪ S. aureus will be catalase positive
▪ Catalase positive – Uses hydrogen
peroxide.
▪ Catalase is needed to convert 2𝐻2𝑂2 →
𝑂2 + 𝐻2𝑂 (nontoxic form). The oxygen
that is present in the reaction will be
observed by the bubbling reaction, when
you subject the colonies to 3%
Hydrogen Peroxide (𝐻2𝑂2)
▪ S. aureus will be catalase positive,
converting H2O2 into its non-toxic for,
H2O and O2 (bubbling reaction)
2 types of coagulase test (Staphy)
Has 2 types: Cell Bound (slide method) and Free
Coagulase (tube method)
detects clumping factor in the surface of
bacterial cells. The plasma fibrinogen in
presence of the clumping factor will
convert fibrinogen into fibrin
▪ Cell-bound coagulase (slide method)
(Fibrinogen → clumping factor →
Fibrin)
detects thrombin-like molecule called
coagulase reacting factor (CRF). The
plasma contains the fibrinogen and the
bacteria react with the
Staphylocoagulase (extracellular
molecule that will react with CRF) which
is now a thrombin molecule that will
convert it into fibrin
▪ Free coagulase (tube method) –
n (Fibrinogen →
coagulase-CRF complex → Fibrin )
MEDIA USED FOR STAPHY
o For the selective media that you can use to culture S. aureus is basically sheep’s blood agar
o You can also use selective media when you are
dealing with heavily contaminated samples or
specimens like wound exudates, etc.
o You can utilize MSA (Mannitol Salt Agar), PEA (Phenylethyl Alcohol Agar) and CNA (Columbia NaladixicAcid Agar)
- Use of selective media from heavily contaminated
specimens (MSA, PEA, CNA)
MICROCOCCUS (pathogen type, loc)
- Environmental organisms
- Normal microbiota of skin and respiratory tract
- Common contaminants
- Coagulase-negative
Laboratory Identification of Micrococcus
(What tests)
- Modified oxidase test (Microdase Test)
- Bacitracin susceptibility (Taxo A Disc)
- Furazolidone resistance (100µg)
If the staphylococcus is not aureus, then most
probably it is .
CNS OR Coagulase-Negative Staphylococcus
CNS
- Found as normal flora in humans and animal
- Often are nosocomial infections
PREDISOSING FACTOR OF CNS
Predisposing factors:
o Catheterization
o prosthetic device implants
o immunosuppressive therapy
OTHER CNS
o S. epidermidis (normal skin microbiota)
o S. saprophyticus (associated with UTIs in
sexually-active, young females)
Laboratory Identification of CNS
- Culture on sheep’s BAP
- Various commercial identification systems may be
used
Antibiotic susceptibility of Staphylococcal
- P resistance is high, especially in S. aureus isolates (85-
90%) - A common resistance is production of enzyme βlactamase (It will neutralize the effect of β-lactam
antibiotics such as Penicillin and Cephalosporins) - Various β-lactamase resistant P have been developed.
Methicillin is the most frequently used. Oxacillin is used for
in-vitro susceptibility testing of methicillin resistance. - MRSA, MRSE (or ORSA/ORSE) are agents of serious
nosocomial and community associated infectionS
Other characteristic feature to identify S. aureus
(Test)
o Mannitol fermentation – Positive
o DNAse test – Positive
o Beta-hemolytic on blood agar
o Golden yellow pigment
– S. aureus
produces yellow color colonies due to fermentation
Mannitol Salt Agar (Selective medium)
You can distinguish S. epidermidis from S. saprophyticus
by virtue of the
Novobiocin persistence tests
Coagulase test will identify
(staphy)
S. aureus being positive and
negative will somehow make you think of the other two
most common coagulase negative staphylococcus which
is the S. epidermidis and S. saprophyticus
streptococcus
- Members are catalase-negative
- Gram-positive cocci arranged in pairs or in chains
- Facultative anaerobes (aerotolerant accrdg to Mahon)
- Use of enriched medium or blood is necessary for their
isolation - Hemolysis patterns are helpful in the identification
4 ways to classify streptococcus:
Nature of disease,
physiologic characteristics, hemolysis pattern, Lancefield
classification (typing of strep by carbohydrate found in
their cell wall)
Streptococcus pyogenes
Group a strep
- Cell wall contains the Lancefield group A carbohydrate
- Lancefield group of classification is the typing or the
classification of streptococcus by the virtue of the
carbohydrate groups found in their cell wall.
virulence factors of s pyogenes
- m protein
- streptolysin o
- streptolysin s
- hyaluronic acid capsule
5.DNAse - Spes A, B, C (erythrogenic toxin)
7.protein f - streptokinase
causes the bacterial cells to resist
phagocytosis by enabling it to adhere to mucosal
cells
m protein
- causes hemolysis of RBCs
(antibodies can be produced, called ASO)
streptolysin o
- causes hemolysis of RBCs
(antibodies can be produced, called ASO)
yses WBCs but not
immunogenic
▪ Antibodies are not created
streptolysin s
responsible for red rashes in scarlet fever
o Spes A, B & C (Erythrogenic toxin) –
– fibronectin binding protein, facilitates
adhesion to epithelial cells
protein f
causes lysis of fibrin clots
streptokinase
infections in s pyogenes
- pharyngitis (strep throat) and tonilitis
- skin infection (e.g. impetigo, necrotizing
fascilitis, etc) - scarlet fever
- rheumatic fever
- streptococcal tss
o Pharyngitis (strep throat) & Tonsilitis
▪ These infections are frequently seen in
children ages from 5 to 15
▪ There is now a rapid strep test that can
be performed that can rapidly diagnose
strep throat
you will see red rash would
appear on the upper chest and it will spread to
the trunk and extremities, following infection with
streptococcus pyogenes
scarlet fever
r (consequence of untreated
pharyngitis) and glomerulonephritis
(immunocomplexes during episodes of
pharyngitis, antigen-antibody reaction)
rheumatic fever
entire organ system shuts
down, happening during very severe
streptococcal infections where it disseminates
into different organ systems and eventually can
lead to death
streptococcal tss
Laboratory Identification of S. pyogenes
(Test and what rxn)
- culture
- gram stian
- bacitricin susceptibility
- resistant to sulfamethoxazole
- pyridium oral test
drug (antibiotic) very useful for
treating superficial skin infections but it is too
toxic for systemic use; polypeptide antibiotic
produced by Bacillus subtilis
bacitracin
Interferes with the peptidoglycan synthesis of
bacteria
bacitracin.
positive siya if may zone of inhibition
Examine for inhibition to sulfamethoxazole
Examine for inhibition. No inhibition means it is
S. Pyogenes
Rapid method for presumptive identification of
bacteria based on the pyrrolidonyl arylamidase
enzyme
pyridium oral test
broth method in pyr test for s. pyogenes qhat colo for positive
red
test result for disc method
▪ PYR Test positive = S. Pyogenes (red
color)
▪ Negative – yellow color
streptococcus agalactiae
(Type of hemolysis, pyr result, cell wall, sxt reaction, location)
- β - hemolytic
- Cell wall contains Lancefield group B carbohydrate
- Group B Streptococcus or GBS (has sialic acid in
capsules, it’s loss will result to loss of virulence) - Found as normal microbiota of the genitourinary tract
- Resistance to SXT
- PYR Negative
group c and g streptococcal
- Not commonly isolated
- Hemolytic species in Lancefield group that are
occasionally isolated from clinical specimens - Part of the normal skin microbiota
- Β-hemolytic
- These groups produce variety of infections including
pharyngitis - Extensive use of biochemical reagents are needed to
identify these groups - Serological tests were developed to identify the group
carbohydrates in the cell wall for group C and G such as
Latex agglutination tests to serotype group C and G
virulence factor of streptococcus agalactiae
o Capsule – main component is sialic acid
o Hemolysin – lyse rbc’s
o Christie-Atkins-Munch-Peterson (CAMP) factor
enlarges the area of hemolysis
o Others (DNAse, hyaluronidase) have not been
shown to be factors in infection
enlarges the area of hemolysis
Christie-Atkins-Munch-Peterson (CAMP) factor
S. Agalactiae Infections
- Neonatal sepsis soon after birth
- Part partum fever and sepsis
Laboratory identification of S. agalactiae
(Tests)
- Culture – genitourinary tract swab, sheep’s blood agar
- Gram’s stain – gram-positive in gram positive long chains,
catalase-negative. In clinical specimen: they will appear in
short chains - CAMP test positive – secreting a protein called CAMP
factor (protein B)
o Christie-Atkins-Munch-Peterson (CAMP) – Test
use for presumptively identifying S. Agalactiae
(because it is the only strep that has the capability
to produce CAMP/Protein B)
- Hippurate hydrolysis positive
appearacne of s agalactiae
o It will appear as greyish white, mucoid colonies
in camp test positive
camp test positive
o When placed perpendicularly with S. aureus, it
will form arrowhead hemolysis (enhanced
hemolysis) that synergistically reacts with the
beta-lysin of sphingomyelinase of S. aureus
o How: in a Sheep Blood Agar Plate streak a
colony of S. Aureus in the middle of the agar then
perpendicularly, streak the suspected S.
Agalactiae. Incubate overnight, then after 18-24
hours observe for the arrowhead hemolysis.
o Presence of arrowhead hemolysis = CAMP
Positive therefore it is a S. Agalactiaeo It will appear as greyish white, mucoid colonies
– not only it can identify S.
agalactiae, it can also detect Campylobacter jejuni, Listeria
monocytogenes, and Gardnerella vaginalis. It detects the
ability of the organism to hydrolyse Hippurate.
Hippurate hydrolysis positive
group c and g examples
- Group C – S. equi, S. zooepidemicus and S. equisimilis
- Group G – S. canis, S. anginosus, S. milleri
group d streptococcal
- Include S. bovis and S. equinus
- Found as normal intestinal microbiota
- May be agents of bacterial endocarditis, UTI’s, abcesses
and wound infections - There are associations with bacteremia caused by S. bovis
and GIT tumor. Isolation of S.bovis from the GIT indicates
presence of tumor
Laboratory Identification of Group D Streptococcus
- a or y.non hemolytic
- positive bile escutin test
- No growth at 6.5% NaCl broth
- PYR negative
- serotyping
– positive reaction is production
of black precipitate due to hydrolysis of the reagent
esculin, in the presence of bile salts
Positive bile esculin test
result of Positive bile esculin test
Positive – Presence of black precipitate due to
the hydrolysis of the reagent esculin
enterococcus
- Found in the intestinal tract
- Most common is E. faecalis. Other members are E.
faecium, E. avium, E. durans - Share characteristics of Group D, including the antigen D
- Show resistance to several of the commonly used
antibiotics
Has similar infections to Group D, the most common being
UTI
Laboratory Identification of Enterococcus
(Tests)
- BE positive, 6.5% positive, PYR positive
- SXT resistant
- Should be screened for high-level aminoglycosideresistant Enterococci (HLARE)
o HLARE that are used are gentamicin, amikacin
that are usually used to treat enterococcus - Vancomycin-resistant Enterococci (VRE) is a major
concern
e used are gentamicin, amikacin
that are usually used to treat enterococcus
high-level aminoglycosideresistant Enterococci (HLARE)
highly resistant strains to most
antibiotics. That is why resistant strains cannot
just be treated with one antibiotic alone. It is
usually combination; synergistic treatment is
being done for enterococcal infection
Vancomycin-resistant Enterococci (VREVancomycin-resistant Enterococci (VRE
viridians treptococci
- Include those α-hemolytic streptococci (greenish
hemolysis, partial hemolysis) that lack Lancefield group
antigens and do not meet the criteria for S. pneumonia - Part of the normal microbiota of the oropharynx and the
intestine - Fastidious and require increased CO2
- Frequent cause of subacute bacterial endocarditis (SBE)
- S. mutans, S. salivarus, S. anginosus, S. mitis, S. bovis –
not hemolytic - NVS (nutritionally variant streptococcus) have been
isolated from patients who have endocarditis and otitis
media - Positive gram-stain, negative culture
o Also known as pyridoxine-dependent (vitamin B6
dependent)
o Vitamin B6 is essential for their growth
NVS (nutritionally variant streptococcus) have been
isolated from patients who have endocarditis and otitis
media
v streptococci
treatmetn of streptococcal and enteroccocal infections
- Most species are susceptible to P
- S. agalactiae is less susceptible than Group A and may
require a combination of Amp and an aminoglycoside - Group D is susceptible to P
- Enterococcus is usually resistant to P
- Enterococcus is usually treated with synergistic
Ampaminoglycoside combination - Pneumococcal isolates are treated with Erythromycin in
case of P-resistant - Linezolid is being prescribed to VRE infections
describe cell wall of s pneumoniae
The cell wall doesn’t have the usual carbohydrate group
by Lancefield. Rather, it has six layers composed of
peptidoglycan and teichoic acid attached to Nacetylmuramic acid, very similar to Group C Lancefield
groups
s pneumoniae
- Often part of the normal flora of the upper respiratory tract
(URT) - Key virulence factor is an anti-phagocytic capsule
- There are approximately 80-90 antigenic capsule types
- An important human pathogen-causing pneumonia,
sinusitis, otitis media, bacteremia, and meningitis
** Isolates may require increased CO2 (capnophilic)
- Colonies are α-hemolytic
- Young cultures produce a round, glistening, wet, mucoid,
dome-shaped appearance
*Gram positive diplococci, having a halo meaning it is
encapsulated. The presence of numerous neutrophils or
polymorphonuclear cells. The presence of WBCs is an
indication of in going infection or inflammation
Direct smears often reveal leukocytes and numerous
gram-positive diplococci with the ends being slightly
pointed, giving a lancet-shaped appearance
s pneumnoniae
s pneumonieae grows on
rows on sheep’s blood agar as α-hemolytic, and βhemolytic when incubated anaerobically
Complex media such as brain-heart infusion agar (BHIA)
or trypricase soy agar (TSA) with 5% blood or chocolate
agar (CAP) are necessary for good growth
Laboratory Identification of Streptococcus pneumonia
- Lanceolate shape (Football shape)
- Αlpha-hemolytic
- Gram positive
- Susceptibility to optochin (Taxo P)
- Bile solubility test
- Quellung test
Inhibits production of ATP in microorganisms. It
makes the cell wall of pneumonia to become
fragile that when the cell membrane becomes
weak, the pneumonia lyses. ≥14mm diameter
zone of inhibition.
- Susceptibility to optochin (Taxo P)* Susceptibility to optochin (Taxo P)
They appear in colonies that are greenish or
alpha-hemolytic
optochin susceptibility test (taxo p)
also an antibiotic that interferes with
production of adenosine triphosphate in
microorganism
optochin
explain bile solubility test in pneumonia
Pneumonia is lysed by bile. Bile salts will lower
the surface tension between the bacterial cell
membrane and the medium. Once the cell
membrane is destroyed, it will accelerate the
organism’s autolysis
o This test will differentiate S. pneumonia which is
soluble by bile from alpha hemolytic which is nonsoluble or insoluble to bile
o The reagent is sodium deoxycholate; for the test
tube is 2%, for plate test 10
bile solubility
Microscopic test in which capsule surrounding
the pneumococci will appear like it is swelling
quellung test
o In some test, they would recommend to put
methylene blue to make it more visible
On microscopy, capsule (seen as clearing around
bacterial cell) becomes apparently swollen,
sharply delineated and refractile
Streptococcus-like organisms
- Aerococcus
- Leuconostoc
- Pediococcus
Laboratory Identification of Streptococci
- BAP hemolysis
- Bile solubility – S. pneumonia is bile-soluble
o There will be clearing in the test tube - Optochin (ethylhydrocuprein hydrochloride/Taxo P)
susceptibility: ≥14mm with 5µg disk - Bacitracin (Taxo A) – S. pyogenes
- Group A and B resistant to SXT
- CAMP test presumptively identifies Group B
Streptococcus – S. agalactiae - Esculin hydrolysis
- 6.5% NaCl
- PYR hydrolysis
o Hemolytic pattern on blood agar plate
o For s. pneumonia it will be mostly alpha hemolytic
bap hemolysis
Other: Laboratory Identification of Streptococci
- LAP test (leucine aminopeptidase) helps differentiate
Aerococcus and Leuconostoc from other Strep species - Serologic testing for the detection of C-Carbohydrate of
the cell wall`
helps differentiate
Aerococcus and Leuconostoc from other Strep species
LAP test
for the detection of C-Carbohydrate of
the cell wal
Serologic testing
types of hemolysis
alpha beta gamma or non
there is a complete clearing of RBC,
because there is a complete lysis of RBC leaving a clear
space where the bacteria grew
beta hemolysis
greenish because of the partial
hemolysis or incomplete hemolysis of the RBC, so there
are still some unused or not completely metabolized RBCs,
not completely lysed RBCs in the process
alpha hemolysis
indicates staphylococcus
- Pin-head colonies white colonies are indicative of
staphylococcus - Pin-point translucent colonies having beta hemolysis is the
usual morphology that you can see while dealing with
streptococcus
Two beta hemolytic streptococcus commonly isolated in
the lab
Streptococcus pyogenes (group A streptococci) o
Streptococcus agalactiae (group B streptococci)
After the preliminary test (gram stain-oxidase), the next
thing that you should do is to differentiate the two beta
hemolytic (pyogenes and agalactiae) by
PYR test
Among the beta hemolytic streptococcus that is PYR
sensitive or positive is
S. pyogenes
o If positive, the color would be violet
After bacitracin sensitivity, if it is sensitive then it is
??? . Once it is PYR positive, you are confirming that
your isolate it
After bacitracin sensitivity, if it is sensitive then it is
pyogenes. Once it is PYR positive, you are confirming that
your isolate is pyogenes
If it is resistant, possibly it is S. agalactiae. You do CAMP
test, if it is positive (arrow head hemolysis) then it is group
B or S. agalactiae.
If Hippurate hydrolysis is positive, then it is also
confirmatory test to
S. agalactiae
To distinguish S. pneumonia to Viridans streptococci, you
do
Optochin sensitivity test
To further identify
Pneumococcus, to confirm it is S. pneumonia. You do
capsular swelling test, bile solubility test (clearing
General Characteristics
of neisseria and moraxella
- Gram-negative cocci often in pairs
- Kidney-bean shaped, capnophilic that will require 10-20% of carbon dioxide
- Oxidase-positive, catalase-positive
- Natural habitat of Neisseria is the mucous membrane of
the urogenital tract - Moraxella and some Neisseria, they are inhabitants of the
mucous membrane of the respiratory tract - Mucous membrane of urogenital tract (Neisseria)
- Mucous membrane of upper respiratory tract (Moraxella
and some Neisseria)
Differentiation of nerisseria and moxarella is based on
acid production from
carbohydrate utilization test
specimen collection for neisseria annd moraxella
Proper specimen collection is
essential for successful
isolation - Specimens should be kept at room temperature
and plated as soon as possible
It is advisable that when you collect samples esp.
vaginal samples or urethro swab samples or
gonococcal infections. Dacron and Rayon swabs
are referred for collections because the use of
cotton swabs will allow them to ba absorb and
you will end up having negative results.
growth requirements of neisseria nad moraxella
Proper specimen collection is essential for successful
isolation - Specimens should be kept at room temperature
and plated as soon as possible
Pathogenic Neisseria gonorrhoeae Virulence factors
- Receptors for human transferrin
- Capsule – polysaccharide capsule
- Pili (T1-T5)
o Piliated types (T1, T2) - Presence of pili indicate
pathogenicity.
o Non-piliated (T3-T5) - Cell membrane proteins (Protein 1-3)
- Lipo-oligosaccharide (LOS) – antigenic variation
- IgA protease – render immunoglobulin A inactivated
cell membranes of neiserria
o Protein I (por) – channel or pore for nutrient and
waste diffusion
o Protein II (opa)– opacity and facilitate adherence
to phagocytic and epithelial cell
o Protein III (rmp) – reaction-modified protein
(RMP) blocks serum IgG; antibodies will not work
gonorrhea
o Infected males show symptoms of burning and
discharge from the urethra
o Females may be asymptomatic but can lead to
pelvic inflammatory disease (PID)
o May cause sterility in males and females
Neisseria gonorrhoeae Infections
- Gonorrhea
- opthalmia neonatorum
- gram stain and location (IC/EC)`
Laboratory Identification of N. gonorrhoeae
(CHCARACTERISTICS)
o Gram-negative diplococci located intracellularly
or extracellularly of neutrophils
o Very important for identifying sexually disease
involving male patients
o Gram stain positive is correlated 95% strong
presumptive evidence of gonorrhea when the
gram stain is positive
LAB IDENTIFICATION OF N. GONORHHOEAE
- Culture using selective agars (Thayer Martin, MTM,
Martin-Lewis and New York City) packaged in selfcontained transport systems such as JEMBEC, Transgrow, GonoPak – allow to have 5% CO2 so they won’t die - Produces acid from glucose utilization (fermentation) but
not for maltose, sucrose, and lactose - Colonies are flat, gray, smooth and glistening
- Other identification Methods:
o Rapid carbohydrate degredation tests
o Chromogenic substrates
o Immunologic assays
o Nucleic acid assays - Carbohhydrate Utilization Test
CARBOHYDRATE UTILIZATION TEST
o Confirmatory test that you could do to identify the
different species of Neisseria
o Using CTA (cysteine tryptic agar) containing 1%
each of these sugars (glucose, maltose, sucrose,
lactose)
o The indicator is always phenol red, when they are
able to ferment the sugar. The acids that will be produced during fermentation will convert the
phenol red into yellow color
Neisseria meningitidis infections
- Primarily these infections are transmitted by droplets,
onset is abrupt - Onset of these infections, you will experience headaches,
stiff neck and fever. Some will have pedicle lesions that
could be present. - Meningococcal meningitis
- Meningococcemia (sepsis)
The brain substance will be inflamed and it can
also progress to BIC, septic shock and therefore
later on it can also lead to hemorrhage of the
adrenal gland (water house friderichsen
syndrome)
- Meningococcal meningitis
Virulence factors
OF NEISWERRIA meningitis
- Pili
- Capsule - Encapsulated strains of N. meningitidis are
ABCYNW135 - POR, OPA, RMP
- LOS endotoxin
Moraxella catarrhis
- Part of the normal URT
- It grows on sputum sample
- It is interpreted as non-pathogenic
- It includes in the family Moraxella acinetobacter and
Moraxella citrobacter - May cause otitis media, sinusitis, and respiratory infections
- Grows on blood, chocolate, and nutrient agars unlike
Neisseria that are very fastidious - Able to reduce nitrate to nitrite
- Produces DNAsE
- Pathogenic Neisseria are subjected to grow on a
selective
agar
