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Discuss characteristics used in identification of organisms:
Lab ident is phenotypic.
╌ Macro and Microscopic morphology
╌ staining characteristics
╌ environmental and nutrient requirements
╌ resistance profiles
╌ antigentic properties
╌ subcellular properties
Gram postive cell wall
80 nm thick
layered peptidoglycan
teichoic acid (holds cell wall and space together so dye is trapped in gram stain)
Gram negative cell wall
thinner but more complex than G+
periplasmic space allows dye to escape.
peptidoglycan--one layer
lipopolysaccharides--o antigens or somatic antigens
responsible for endotoxins
Acid fast cell walls
modification of G+
contains mycolic instead of teichoic acids
Endospores
dormant or resting stage in growth cycle. Formed in responce to nutritional deprivation
Seen only in Bacillus and Clostridium spec.
Capsules
slime layer external to outer layer of cell wall
Flagella
responsible for motility
most common in g- rods, but alls in g+ rods (Listeria) and cocci (Enterococus)
Fimbrae or pili
adherance and/or genetic exchange
Pathogenicity
ability of organism to cause disease
Organism must be able to enter host and cause disease
some release toxins that cause pathologic process
Must cause host reaction
Virulence
degree of pathogenicity of species
virulence factors
adhesins/receptors
Agressins
Functions of virulence factors
Extracellular adherance
Impair complement function
Lytic effects on neutrophils
bind to immunoglobulins
Adhesins
allow microorganism to bind to cell surface via receptors
Agressins
substances that allow organisms to override host defense mechanisms:
surface proteins and carbohydrates
enzymes
endo- and exotoxins
other small molecules
Capsules
avoid phagocytosis by covering up antigenic compounds
facilitates colonization
Surface proteins
adherence and virulence
vary by organism
catalase and superoxide dismutase
ihibit organis destruction by myeloperoxidase system of phagocitic cells
Leukocidins
causes degranulation, swelling and lysis of neutrophils
Hyaluronidase
depolymerizes hyaluronic acid (responsible for cell-cell adhesion)
streptokinase and staphylokinase
hydrolyze fibrin clots to facilitate invasion
collagenase
breaks down collagen matrix of muscle and connective tissue
causes necrotizing fascitis and gas gangrene
Exotoxins
most potent
produced mostly by g+
tetanus diphtheria, botulism and cholera are examples
organism must be alive to exude
endotoxins
produced only by G- organisms
low in toxicity
worse when organism is dead.
low dose: fever
High dose: hypotension, DIC, hemorrhage
Siderophores
scavenge iron from host
protect against killing effect of normal human serum
R factors
R factors code for resistance to antimicrobial agents
Plasmids
code for sex pili, chromosome mobilization, colonization antigens, serum resistance, iron chelation and transport, toxin and hemolysin production
Primary defenses
Anatomic barriers
intact skin
nasal hairs
cilia in resp tract
mucous layer lining gut
flow of liquids in resp and intestinal tracts
Normal flora
Primary defenses
Physiologic factors
high or low pH or oxygen tensions
chemical inhibitors to bacterial growth
prssence of bile acids, lysozymes, fatty acids
Secondary defenses
humoral substances: complement, lysozyme, opsonins
Phagocytosis: neutrophils and macrophages
humoral antibodies: IgG, IgA
Cell mediated immune responses
other factors affecting host resistance
age (young & old very susceptible)
Chronic or debilitating disease
short or long term therapy
toxc ingestion of alcohol and drugs
trauma, stress, foreign materals at site of infection
Specimen collection
avoid exposures to extreme heat and cold, rapid pressure changes or excessive drying.
deliver to lab within 30 minutes
specimen transport
transport media:designed to preserve viability of bacteria without allowing multiplication. Anticoagulants
rejection of specimens
mismatched label and requisition
late delivery to lab
QNS-quantity not sufficient
Nutritive media
Support growth of wide range of organisms. Nonselective because of growth of most organisms is supported
Differential media
nutritive, allow organisms to be distinguished based upon growth characteristics
Blood is nutritive and differential because allows to see hemolysis
Selective media
Supports growth of one group over another.
MacConkey agar:
Crystal violet inhibit growth of Gram positive organisms, so select for Gram negative
Columbia CNA agar:
adds colistin and naladixic acid to Columbia agar to inhibit growth of Gram negative organisms and so selects for Gram positive organisms
Ambient conditions
21% O, 0.03% CO₂
Anaerobic conditions
5-10% H₂, 5-1-% CO₂, 80-90% N₂ and NO O₂
Capnophilic conditions
5-10% CO₂, 15% O₂
Microaerophilic
5-10% O₂, 8-10% CO₂
Methods available for Lab ID of organisms

Microscopy
Wet preps and various stains
Methods available for Lab ID of organisms

Cultivation on solid and in liquid media
Enrichment, supportive, selective, and differential
Methods available for Lab ID of organisms

Conventional biochemical methods
single enzyme screening
substrate utilization
metabolic activity
tube vs. commercial ID panel
Methods available for Lab ID of organisms

Molecular methods
DNA probes, PCR-based methods
Methods available for Lab ID of organisms

Chromatography
GLC, HPLC
Methods available for Lab ID of organisms

Protein Electrophoresis
Western blotting
Methods available for Lab ID of organisms

Immunochemical electrophoresis
Agglutination, precipitation, IFA, EIA, ELISA, SPIA
Serologic diagnosis
Methods available for Lab ID of organisms

Antimicrobial resistance
Kirby-Bauer, MIC, E-test, Novabiacin
Genera in family Micrococcaceae
Staphylococcus
Micrococcus
Epidemiology of Staph infections
usually normal flora
Infection caused when enters normally sterile site. Only needs tiny breaks to enter skin or mucosa
Transmission of Staph infections
transmitted from person to person
also during surgery
catheters (UTIs)
serious cause of nosocomial infections
Pathogenesis of S. aureus

Localized skin infections:
minor: impetigo
serious: boils, carbuncles
spread from exotoxins and enzymes may cause deeper tissue infection, bacteremia, and spread to internal organs
Pathogenesis of S. aureus
Toxin mediated diseases

Scalded skin syndrome:
neonates, caused by exfoliatin toxins
extensive sloughing of skin to cause burnlike effect
Pathogenesis of S. aureus

Toxin mediated diseases

Toxic shock syndrome
organisms localized, but toxic effects systemic: fever, desquamation, hypotension can lead to shock and death
Pathogenesis of S. aureus
Toxin mediated diseases

food poisoning
Elaboration of exotoxins during growth in contaminated foods

common
Pathogenesis of S. aureus
Toxin mediated diseases

Bacteremias
bacteria in blood. Seen mostly in immunocompromised people
Pathogenesis of S. aureus
Toxin mediated diseases

community acquired bronchopneumonia
usually in elderly
associated with viral pneumonia
Pathogenesis of S. aureus
Toxin mediated diseases

nosocomial infections
usually occurs as result of obstructive pulmonary disease, intubation, and aspiration
Pathogenesis of S. aureus
Toxin mediated diseases

Stapylococcal meningitis
patients with CNS abnormalities related to trauma, surgery, malignancy, and hydrocephalus
second most common cause of ventriculoperitoneal shunt-associated meningitis
Pathogenesis of S. aureus
Virulence factors

Capsule formation
Exopolysccharide to evade immune system and prevent ingestion by neutrophils

promotes adherence to host cells and prosthetic devices
Pathogenesis of S. aureus
Virulence factors

Hemolysins
α-hemolysin: lyse neurtophils and RBCs, potent neurotoxin, dermonecrotic (takes out RBCS, WBCs, nerve cells & skin cells)

β-hemolysin: biphasic, lyse RBCs exposed to cold. responsible for Camp test positive with Group B Strep.
Pathogenesis of S. aureus
Virulence factors

Protein A
binds Fc portion of immunoglobulins
shed into medium during growth
interferes with opsonizations, activates complement, and elicits both immediate and delayed type hypersensitivity reactions.
Coagglutination tests specific for this protein
Pathogenesis of S. aureus
Virulence factors

cell wall constituents
teichoic acids for adherence to mucosal surfaces
rigidity and structure
activate complement, inhibit chemotaxis, stimulate antibody production
Pathogenesis of S. aureus
Virulence factors

Toxins-Leukocidin
degranulates, swells and lyses neutrophils
Pathogenesis of S. aureus
Virulence factors

Toxins-Exfoliatins
dissolve mucopolysaccharide matrix of skin to cause scalded skin syndrome
Pathogenesis of S. aureus
Virulence factors

Toxins-TSS toxins
potentiates lethal response to minute amounts of gram negative endotoxin
superantigens (bind directly to monocytes and lymphocytes) resulting in release of cytokines
causes rapid multisystem involvement
Pathogenesis of S. aureus
Virulence factors

Enzymes-Catalase
inactivates toxic hydrogen peroxide and free radicals formed by myeloperoxidase system of phagocytic cells
Pathogenesis of S. aureus
Virulence factors

Enzymes-Coagulase
coats bacteral cells with fibrin, rendering them resistant to opsonization and phagocytosis
Pathogenesis of S. aureus
Virulence factors

Enzymes-Hyaluronidase and fibrinolysins
spread bacteria through host by breakdown of tissues
Pathogenesis of S. aureus
Virulence factors

Enzymes-beta-lactamases
3 different types
render penicillin useless
Staphylococcus aureus
Gram positive cocci
– sheep blood agar
• ß hemolytic
• mannitol fermentation (yellow halo)
• Golden pigmented (aureus)
• coagulase-positive
• catalase-positive
Deoxyribonuclease (DNase)-positive
thermostabile endonuclease-positive
Coagulase negative staphylococci
S. epidermidis is the most commonly encountered
Also includes S. haemolyticus, and S. saprophyticus
Coagulase negative staphylococci

Nosocomial infections
related to medical procedure and organisms ability to colonize
Their ability to produce a slime layer and attach to medical devices and their ability to acquire antibiotic resistance enhance the likelihood of infection
S. epidermidis, S. haemolyticus
Coagulase negative staphylococci

Urinary tract infections
UTI’s caused by S. saprophyticus most commonly associated with young, sexually active females

2nd only after E. coli
Primary virulence factor allows for adherence to epithelial cells of the urinary tract, but not to skin or the mucosal surfaces
Also produces urease to improve tissue invasion
Coagulase negative staphylococci

Pathogenesis
Infections of indwelling devices
Due to production of extracellular slime substance
Bacteremia in compromised hosts
Native and prosthetic valve endocarditis
Postsurgical or trauma-associated wound infections
Most frequently found as contaminants in clinical specimens
Gram Positive Cocci
Media selection
Mannitol Salt agar isolate staphylococci from normal flora Has a high salt concentration of 10%, the sugar mannitol, and phenol red as a pH indicator
grow in the presence of salt and ferment mannitol, colonies surrounded by a yellow halo
Yellow halo is characteristic of S. aureus, but other staphylococci, especially S. saprophyticus, can look the same on MSA
Catalase test
Catalase test
Differentiates the Micrococcaceae from the Streptococcaceae
Detects the presence of cytochrome oxidase enzymes.
Bubbling indicates the conversion of the hydrogen peroxide to water and oxygen gas.
Glucose fermentation test
Detects acid production from the utilization of glucose under anaerobic conditions
Species of Staphylococcus are positive while other species such as Micrococcus are negative
Lysostaphin susceptibility
An endopeptidase that cleaves the glycine-rich pentapeptide cross-bridges in the staphylococcal cell wall peptidoglycan Renders the cells susceptible to osmotic lysis
Micrococcus is negative, Staphylococcus is positive
Furazolidone test
Antibiotic sensitivity test

Staphylococci are inhibited by furazolidone and show zones of inhibition of 15 mm or more, while Micrococci are resistant and may show zones of 6 to 9 mm
Modified oxidase test (microdase)
Filter paper disks impregnated with tetramethyl-p-phenylenediamine dihydrochloride (oxidase reagent) in dimethyl sulfoxide (DMSO) are used
Most strains of Staphylococci (with few exceptions) are oxidase negative while Micrococci and related species are oxidase positive
Bacitracin susceptibility
Antibiotic susceptibility
Staphylococci are resistant and grow to the edge of the disk, while micrococci are susceptible with zones of 10 mm or larger
Coagulase Test
Enzyme binds plasma fibrinogen and causes plasma to clot, two types of coagulase, either bound or free
Desferroxamine susceptibility
S. epidermidis and S. hominus are susceptible while all other strains are resistant
Novobiocin susceptibility
Novobiocin resistant species other than S. saprophyticus are rarely encountered in human specimens
Resistance to this antibiotic is considered a presumptive diagnosis for S. saprophyticus
TMPA agar (trehalose-mannitol-phosphatase)
Acid production is indicated by a color change from purple to yellow and phosphatase activity is detected by spotting a colony from the medium onto filter paper moistened with 1N ammonium hydroxide
Phosphatase positive colonies produce a pink color.
organisms in the family Streptococcaceae that most commonly cause human infections
S. pyogenes
S. agalactiae
S. pneumoniae
Viridans streptococci
Enterococci (usually E. faecalis or E. faecium)
Catalase negative Gram Positive Cocci

General Characteristics
facultative anaerobes capnophilic
homofermentative (produce lactic acid)
Oxidase negative
gram positive cocci that grow in chains
some classified by Lancefield groupings
Catalase negative Gram Positive Cocci

Epidemiology
normal flora
Opportunistic pathogens
S. pneumoniae-normal upper respiratory flora, leading cause of bacterial pneumonia and meningitis
S. pyogenes-rarely considered normal flora
Catalase negative Gram Positive Cocci

Epidemiology-Transmission
Spread person to person by various means and establish colonization
Infections when organism is in sterile sites
Access gained during trauma to skin or mucosal surfaces or aspiration into the lungs from the upper respiratory tract--Seen with S. pneumoniae
Catalase Negative Gram Positive Cocci

Virulence factors
M proteins
Opacity factor
Streptolysin O
Streptolysin S
Extracellular toxins
Type specific cell surface antigens
M proteins
major virulence factor of the group A streptococci, Difficult to destroy, Causes resistance to phagocytosis and intracellular killing by neutrophils
Opacity factor
Another M protein-associated cell surface antigen of Group A Strep that is a probable virulence factorOnly associated with certain M types (about 29 of the 80)
Streptolysin O
Responsible for the β-hemolysis of the Group A Strep under anaerobic conditions (very sensitive to oxygen)
Also produced by some group C and G strep
ASO titers measure antibodies against this protein and are useful to diagnose recent pharyngeal Strep infections (after recovery)
Streptolysin S
Oxygen-stable and actively participates in both aerobic and anaerobic hemolysis by the Group A Strep, probably responsible for destroying the WBC's that ingest the Group A Strep
Extracellular toxins
Streptococcal pyrogenic exotoxins
Responsible for the rash of scarlet fever
Also likely to be responsible for toxic shock-like syndrome
Catalase negative Gram Positive Cocci

Enzymes
DNAse
Hyaluronidase
breaks down connective tissue and allows spreading)
Streptokinase
hydrolyzes fibrin clots and allows for spreading)
S. pneumoniae

virulence factors
adhesins, an α-hemolysin, pneumolysin, autolysin and pneumococcal surface protein
resistance=polysaccharide capsule (84 types, 23 cause pneumococcal bacteremia and meningitis) vaccine is against those 23
Group B Strep
Surface antigens prevent phagocytosis
Increase virulence and survival of the organisms
Beta-hemolytic Streptococci Group A (S. pyogenes)
person to person-respiratory
streptococcal pharyngitis
skin infections-impetigo
Beta-hemolytic Streptococci Group A (S. pyogenes)
Suppurative complications
Peritonsillar abscess
Retropharyngeal abscess
Cervical adenitis
Otitis media
Sinusitis
Mastoiditis
Bacteremia
Beta-hemolytic Streptococci Group A (S. pyogenes)
non-suppurative complications
Acute rheumatic fever
Glomerulonephritis
Toxic shock like syndrome
ARF (acute rheumatic fever)

Secondary infection after pharyngitis
Usually presents with a migratory arthritis, characteristic heart murmurs, cardiac enlargement, CHF or rarely, intractable cardiac arrest and death
ARF (acute rheumatic fever)

Lab Findings
Lab findings
Increased ESR, increased CRP, previous Strep infection, increased or rising Strep antibody titers (ASO, anti-DNase B, anti-hyaluronidase
Glomerulonephritis

Secondary infection after pharyngeal or skin infection
Presents as glomerular inflammation with glomerular lesions, hypertension, hematuria and proteinuria
Symptoms include malaise, weakness, anorexia, headache, edema and circulatory congestion (hypertension and encephalopathy)
Glomerulonephritis

Lab findings
Anemia, increased ESR, decreased C3 and total complement, hematuria and proteinuria
UA reveals RBC’s, WBC’s and casts
ASO is unreliable so anti-DNase B or anti-hyaluronidase should be performed
TSLS (Toxic Shock-like Syndrome)

Associated with Exotoxin A produced during scarlet fever
Promote rapid systemic invasion
Precipitate the multi-organ system involvement
severe with high mortality rate
Beta-hemolytic Streptococci Group B (S. agalactiae)

Major cause of disease in neonatal and perinatal periods
Newborn colonized either in utero or during delivery (sometimes nosocomial exposure)
Onset: first 5 days, but most within the first 12 to 24 hours
Symptoms include bacteremia, pneumonia, meningitis, septic shock and neutropenia
Beta-hemolytic Streptococci Group C
Produce hemolysins similar to those of the Group A Strep
S. dysgalactiae also carries the group C antigen, but is alpha or non-hemolytic
Most patients infected with these organisms have underlying diseases
Beta-hemolytic Streptococci
Group D (S. bovis and S. equinus)
Usually alpha or nonhemolytic on sheep blood agar, but beta hemolytic on rabbit blood agar
Usually infects patients with underlying diseases or malignancies
Beta-hemolytic Streptococci
Group F
May be beta, alpha or non-hemolytic
Can cause severe suppurative infections, but again, most patients infected with these organisms have significant underlying disease
Beta-hemolytic Streptococci
Group G
Normal human gastrointestinal, vaginal, oropharyngeal, and skin flora
Can cause severe infection of bone and joint prostheses
Also can cause pharyngitis, otitis media, cellulitis, etc
Alpha-hemolytic Streptococci
S. pneumoniae

Major cause of community acquired bacterial pneumonia
Serious infections: infants and children under 2, late middle-aged and elderly adults
Alpha-hemolytic Streptococci
S. pneumoniae

Principle virulence factor
polysaccharide capsule

Antimicrobial resistance is becoming a serious concern especially to penicillin and related drugs
Viridans streptococci
alpha and nonhemolytic Strep, most of which are part of the normal upper respiratory tract and urogenital tract flora
subacute bacterial endocarditis (valvular disease, or prosthetic valves) Circulating immune complexes: paravalvular abscesses and glomerulonephritis, dental caries
Resistance to antibiotics makes these organisms difficult to treat
Enterococci

Normal flora: GI and biliary tracts, the vagina and urethra of males
UTI’s, bacteremia, endocarditis, intra-abdominal and pelvic infections, wound and soft tissue infections, neonatal sepsis and rarely, meningitis
antibiotic resistance to penicillins and cephalosporins, and even to vancomycin
Enterococci

Virulence factors
cytolysin that acts as a hemolysin against human, rabbit, equine and bovine RBC’s, but not sheep RBC’s, aggregation substance, pheromones(nymphobacteria), bacteriocidin, gelatinase and/or hyaluronidase
Enterococci

Lab Findings
10°C to 45C, can grow in the presence of 6.5% NaCl, grow at a pH of 9.6, are bile esculin positive and PYR positive
Catalase Negative GPC
Identification Process
Gram positive cocci in pairs (pneumococci) and chains (most others)
Groups ABCFG-beta hemolytic
enterococci, group D, occasional group B-alpha or nonhemolytic
All are catalase negative
Catalase Negative GPC
Bacitracin sensitivity in conjunction with SXT
presumptive identification of Group A Strep Any zone of inhibition is considered positive--some Group CG and B Strep are also susceptible, so perform with the SXT susceptibility test because Groups C and G are usually susceptible to SXT and Groups A and B are resistant. Always report as “presumptive” Group A Strep
Catalase Negative GPC
Sulfamethoxazole-trimethoprim sensitivity (SXT)
Group A and B are resistant, Groups CF and G are susceptible

Any zone of inhibition is considered positive:
(A/SXT) S/R = presumptive Group A Strep
R/R = Presumptive Group B Strep
Var/S = Non Group A or B
Optochin sensitivity
Ethyl hydrocupreine hydrochloride used to differentiate S. pneumoniae from other Viridans Strep
14 mm or more indicates susceptibility=pneumococci
CAMP test
Named for Christie, Atkins and Munch-Petersen
Presumptive identification of Group B Strep
use with S. aureus
Sodium hippurate hydrolysis
Group B strep can hydrolyze hippurate to glycine and benzoic acid

Ninhydrin can also be added to detect glycine
Under these circumstances a deep blue color is positive
Bile esculin test
presumptive ID of Group D Strep and Enterococci
positive can grow in the presence of 40% bile and hydrolyze esculin
production of esculetin (from esculin hydrolysis) turns the agar black
Growth in 6.5% NaCl
separate the Enterococci from the Group D Strep
Species of Enterococci are salt tolerant, while the Group D Strep are not
Pyrrolidonyl arylamidase test (PYR)
presumptive test for Group A strep and Group D Enterococcal species

replaces bacitracin for Group A and salt tolerance for Enterococci
Leucine aminopeptidase test
Production of LAP along with PYR can help identify Strep, Enterococci and some of the Strep-like organisms

All Strep and Enterococci are positive, separating them from the other Strep-like organisms
Spore-forming, aerobic or facultatively anaerobic rods
Bacillus sp
Morphologically regular, non-spore-forming bacilli
Erysipelothrix sp
Gardnerella sp
Lactobacillus sp
Listeria sp
Irregular or coryneform, non-spore-forming bacilli
Dermabacter sp
Corynebacterium sp. Microbacterium sp
Bacillus species

General
Usually grow well on blood agar, producing large spreading, gray white colonies with irregular margins
many are beta-hemolytic
most are catalase positive
sporulation is not inhibited by aerobic incubation
helps distinguish from Clostridium, an anaerobe GPB spore-former
Ubiquitous, inhabiting soil, water and dust
Thermophilic members can grow at extreme temperatures (58-75C)
Psychrophilic members can live in extremes of acidity and alkalinity (pH 2-10)
Bacillus species
Disease Processes - Anthrax
Very rare in the US, but is seen in some other countries.
It has 3 cycles: multiplication of spores in the soil, animal infection and human infection
Anthrax spores can remain infectious for decades
skin infections
inhalation anthrax-almost always fatal
Penicillin, ciproflaxacin, tetracycline,and a vaccine
B. anthracis

exotoxin
Edema factor (EF): the extracellular form of adenylate cyclase
Protective Antigen (PA): Promotes entry of EF into phagocytes
Lethal Factor (LF): Causes pulmonary edema and death in rats
B. cereus


food poisoning
Toxin mediated disease, not an infection
2 toxins: Emetic toxin that causes vomiting
Enterotoxin that causes diarrhea
Anthrax identification
Large Gram positive bacilli with square or concave ends
non-hemolytic on SBA
motility negative
API strips
sensitive to penicillins and cephalosporins
B. cereus identification
SBA-usually beta hemolytic
API strips
Motile
resistant to penicillins and cephalosporins
Regular, Non-spore Forming Rods – Listeria Species

General
Gram positive, motile rod
endotoxin
neonates-under 3 months
elderly
stinky mexican cheese, ice cream
fetal death
facultative intracellular pathogens (live in monocytes-macrophages)
cold enrichment (transport)
Regular, Non-spore Forming Rods – Listeria Species

Identification
Non-spore-forming, short, Gram positive rod
intracellularly or extracellularly, and sometimes as pairs
blood agar or CNA
colonies: small, translucent VERY narrow zone of beta-hemolysis
Catalase positive
tumbling motility and umbrella
CAMP positive
sodium hippurate positive
grows at 4°C
ferments glucose, trehalose salicin,
esculin positive
H2S negative
Regular, Non-spore Forming Rods--Erysipelothrix

E. rhusiopathiae
Short, slim Gram positive rod
Erysipeloid, a skin disease
blood agar
nonmotile
catalase negative
alpha- or non-hemolytic
Produces H2S in TSI or KIA
resistant to vancomycin
Regular, Non-spore Forming Rods-- Lactobacillus
Non-spore-forming Gram positive rods,chains
homofermentative-lactic acid from glucose fermentation
resistant to vancomycin
nonmotile
blood or chocolate agar
growth on tomato juice agar
Non-hemolytic
catalase negative
H2S in TSI--negative
esculin-negative
Irregular Non-spore Forming Rods
Many V and L shapes are present on Gram stains
“Chinese letter" forms or "diphtheroid" appearance
Irregular Non-spore Forming Rods - Corynebacterium
Gram positive
non-branching
non acid-fast
all but one are non-motile
catalase positive
ferment glucose and other sugars
aerobes or facultative anaerobes
C. diphtheriae
acute, contagious, febrile illness
exotoxin-necrosis of heart
pseudomembrane-oropharynx
Potassium tellurite-isolate from normal flora grayish-black after 24-48 hours
Tinsdale medium and cystine-tellurite (CT) blood agar-differentiate C. diphtheriae from other corynebacteria
Erythromycin and penicillin
Gardnerella vaginalis
Gram variable (Gram negative to weakly Gram positive)
bacterial vaginosis, asymptomatic in many women
Clue cells (epi’s colonized with surface bacteria) offer presumptive diagnosis
Addition of 10% KOH releases strong fishy odor and aids in presumptive diagnosis
sexually transmitted organism
Gram Negative Cocci

General
nonmotile
non-spore-forming
grow best at 35-37°C
Capnophilic
moist environments
produce acid from carbohydrates
Oxidase and catalase positive
Gram Negative Cocci
Virulence Factors
lipooligosaccharides--no O surface antigen..allows for antigen variablity to fool immune system
Gram Negative Cocci
Virulence Factors

Pili
N. gonorrhoeae
N. meningitidis
Long hairlike proteins
mediate attachment to host cells and probably to each other for the purpose of exchanging genetic material between organisms
prevent phagocytosis by neutrophils
Gram Negative Cocci
Virulence Factors

Outer membrane proteins (Omp)N. gonorrhoeae
Protein I-controls in and out of the cell
Opacity proteins (Opa)-mucosal adherence
Protein III--prevent binding of antibodies
Gram Negative Cocci
Virulence Factors

N. meningitidis
Polysaccharide capsules-resistant to phagocytosis
looks just like human neuraminic acid
Gram Negative Cocci
Virulence Factors

N. gonorrhoeae
N. meningitidis
Proteases
Nutritional requirements
Beta-lactamases
N. gonorrhoeae
Sexually transmitted
Acute urethritis-males
Endocervical infection-females
Ocular infections-primarily neonates
Disseminated gonococcal infection (DGI
bloodstream infection
Usually characterized by fever, hemorrhagic skin lesions, and various forms of arthritis
N. meningitidis

General
Humans are the only natural host
Spread by respiratory droplets
young adults living in close quarters

asymptomatically in the oropharynx or nasopharynx
Second leading cause of community acquired meningitis in the US
confusion, headache, fever and nuccal rigidity, but seen in only half of the patients
30% of cases are fatal
10% of survivors-sensorineural deafness
N. meningitidis

Petechiae
Small hemorrhagic skin lesions indicitave of meningococcemia

development of coagulopathies because of infection
N. meningitidis

Meningococcemia
Can also occur without meningitis, but is usually not fatal
N. meningitidis

Conjunctivitis
Secondary complication to meningitis
Primary conjunctivitis has also been reported
Can lead to corneal ulcers, keratitis, subconjunctival hemorrhage and iritis
N. meningitidis

Purpura fulminans
Extensive areas of tissue necrosis secondary to coagulopathy
Shock, low WBC count, rash and altered mental status are associated with a poor outcome
DIC may cause death
N. lactamica
Very rarely causes meningitis, but has been associated with recurrent otitis media
May be the source of antimicrobial resistance genes among the meningococci
Moraxella catarrhalis
Seen at higher rates in children with asthma
otitis media and acute sinusitis of children
bronchitis and pneumonia of older adults
Neisseria gonorrhoeae

Specimen collection
Dacron or rayon swabs
Nutritive transport systems have the capability to produce CO2 rich environments
JEMBEC plates
Gono-Pak
N. meningitidis

Transport
No special handling is required except for the occasional genital specimen and blood specimens
Handle like GC specimens
Gram Negative Cocci

Isolation of pathogenic Neisseria
Thayer-Martin (MTM), Martin-Lewis, New York City, and GC-Lect
Grow best at 35-37C in 3-7% CO2
Oxidase positive
Gram neg diplococci
Superoxol test
30% hydrogen peroxide (not 3%) used
N. gonorrhea produces immediate vigorous bubbling while other species produce delayed bubbling
Carbohydrate Utilization

main identification method
N. Gon=+ for Glucose
N. Men=+ Glu, Mal
N. Lact=+, Glu, Mal, Lac
N. sicca=+ Glu, Mal, Lac, Suc