-
Staphylococci (Clusters)
- Grape-like clusters
- Normal human flora
- Opportunistic pathogens
- • Skin, soft tissues, bones, and urinary tract
- Species:
- Staphylococcus Aureus
- Staphylococcus Epidermidis
- Staphylococcus Saprophyticus
-
Staphylococcus Aureus
- catalase +
- Coagulase +
- B-hemolytic yellow colonies
- Mannitol Fermentation
- Novobiocin Sensitive
- o Most frequently isolated nosocomial pathogen (hospital-acquired infection)
- o Virulence Factors:
- Cytotoxins: toxic for many cell types
- Exfoliative Toxins: serine proteases in two forms, ETA (heat stable) and ETB (heat labile, A/B toxin)
- • Causes Staphylococcal scaleded skin syndrome (SSSS)
- Enterotoxins: heat stable, superantigen
- • Responsible for food-poisoning and sometimes toxic shock
- Toxic Shock Syndrome Toxin-1 (TSST-1): heat stable, superantigen
- • Causes toxic shock
- Enzymes:
- • Coagulase
- • Catalase
- • Hyaluronidase
- • Staphylokinase
- • Lipase
- • Nuclease (useful in identifying S. aureus)
- • Penicillinase
- Structural Components:
- • Glycocalyx (inhibits phagocytosis)
- • Peptidoglycan (endotoxin-like activity)
- • Teichoic acids (promote bacterial adherence)
- • Protein A (ONLY IN S. aureus)
- o Diseases:
- Cutaneous infection (most common)
- • Impetigo
- • Folliculitis
- • Carbuncles
- • Wound infection
- toxin-mediated syndromes
- • Food poisoning: contaminated with heat stable enterotoxins
- • SSSS (Riter’s): caused by exfoliative toxins
- • Toxic-Shock: caused by TSST-1
- systemic diseases
- • Bacteremia: spread of bacteria into the blood from a focus of infection
- o Endocarditis and osteomyelitis
- • Pneumonia
- Staphylococci (Clusters)
- Grape-like clusters
- Normal flora on human skin and mucous surfaces
- Opportunistic pathogens in humans causing a wide spectrum of diseases
- • Skin, soft tissues, bones, and urinary tract
-
Staphylococcus Epidermidis
- catalase +
- Coagulase -
- G-hemolytic white
- o Famous biofilm former on invasive medical devices
- o Virulence Factor: Glycocalyx
- o Major cuase of endocarditis in valve replacement surgery
- Staphylococci (Clusters)
- Grape-like clusters
- Normal flora on human skin and mucous surfaces
- Opportunistic pathogens in humans causing a wide spectrum of diseases
- • Skin, soft tissues, bones, and urinary tract
-
Staphylococcus Saprophyticus
- catalase +
- Coagulase -
- G-hemolytic white
- o 2nd most common cause of UTI
- o Use direct microscopic observation for lab diagnosis
- Staphylococci (Clusters)
- Grape-like clusters
- Normal flora on human skin and mucous surfaces
- Opportunistic pathogens in humans causing a wide spectrum of diseases
- • Skin, soft tissues, bones, and urinary tract
-
Streptoccoi (Pairs and Chains)
- catalase -
- Most abundant group in oral cavity
- Facultative
- 3 overlapping classification schemes:
- • Hemolysis
- • Lancefield grouping (used only to distinguish among the B-hemolytic species)
- • Biochemical properties
- Species:
- S. pyogenes
- S. agalactiae
- S. pneumoniae
- S. bovis
-
S. agalactiae
- GPC
- catalase -
- Group B Lancefield
- o Epidemiology: Asymptomatic colonization of female genital tract and lower gastrointestinal tract
- o Diseases: Baby Killer!
- Early onset neonatal disease: Sepsis, meningitis, pneumonia
- Late onset neonatal disease: bacteremia with meningitis
- Infection in pregnant women: present as UTI
- Infections in other adult patients: bacteremia, pneumonia, bone and joint infections, skin and soft tissue infections
- o Lab Diagnosis:
- CAMP: only S. agalactiae produces the CAMP factor, will see an enhanced zone of hemolysis due to the presence of CAMP factor
- Hippurate Hydrolysis Test: Hippuricase is produced by S. agalactiae, causes a precipitation when ferrin chloride is added
- Group B specific carbohydrates: polymer of rhamnose, N-acetylglucosame, and galactose
- Surface Protein: C protein
- Streptoccoi (Pairs and Chains)
- catalase -
- Most abundant group of bacteria in oral cavity
- Facultative
- 3 overlapping classification schemes:
- • Hemolysis
- • Lancefield grouping (used only to distinguish among the B-hemolytic species)
- • Biochemical properties
-
S. pneumoniae
- GPC
- catalase -
- (NO Lancefield because it is A-hemolytic)
- o Has fastidious growth requirements
- o Leading cause of pneumonia in adults today
- o Virulence factors:
- Capsule: major virulence factor, antiphagocytic
- • only virulent strain has capsule
- o Epidemiology:
- Most infections are caused by endogenous spread (non-communicable)
- Person-to-person spread is extremely rare
- o Disease:
- Otitis Media: inflammation of the middle ear
- Bacterial pneumonia: inflammation of the lungs
- Bacteremia
- Meningitis: inflammation of the protective membranes covering the CNS (meninges)
- o Lab Diagnosis:
- Optochin Sensitivity Test: only pneumoniae is inhibited by Optochin
- Bile solubility test: only pneumoniae produces amidase which lyses bile and creates a clear bacterial culture
- Quellung: swelling of the capsule surrounding a bacterium
- Streptoccoi (Pairs and Chains)
- catalase -
- Most abundant group of bacteria in oral cavity
- Facultative
- 3 overlapping classification schemes:
- • Hemolysis
- • Lancefield grouping (used only to distinguish among the B-hemolytic species)
- • Biochemical properties
-
S. bovis
- GPC
- catalase -
- Group D, indicator of colon cancer
- Streptoccoi (Pairs and Chains)
- catalase -
- Most abundant group of bacteria in oral cavity
- Facultative
- 3 overlapping classification schemes:
- • Hemolysis
- • Lancefield grouping (used only to distinguish among the B-hemolytic species)
- • Biochemical properties
-
Viridans Streptococci:
- Group of about 20 members including most dental bacteria
- o Important cause of endocarditis after dental manipulation
-
Enterococci (diplococci)
- Gamma Hemolytic
- Virulence factors:
- • Intrinsic antibiotic resistance (notorious for this genus)
- o Resistant to many beta-lactam drugs
- o Also vancomycin resistant
-
Gram-Positive Bacilli
- o Spore-Formers: Always gram positive because need the large peptidoglycan layer and cannot have outer membrane
- o Bacillus: gram positive rods
- • B. antracis
- • B. cereus
-
B. antracis
- GPB-spore
- spore-former
- o Aerobic, non-motile, and G-hemolytic
- o Causes Antrax
- o Virulence Factors:
- Three exotoxins (NOT A/B toxins)
- • Protective antigen (PA)
- • Lethal factor (LF)
- • Edema factor (EF)
- • NOTE: must have PA in order to be virulent
- Capsule: consists of D-glutamate polypeptide
- Spore
- o Epidemiology: No evidence of person-to-person transmission of antrax
- True Zoonotic Pathogen
- o Diseases
- Cutaneous Anthrax (most common form)
- • Malignant pustules form on the surface of skin after minor scratch or abrasion with bacteria
- Gastrointestinal Anthrax (forms ulcers)
- Inhaled Anthrax
- • Most lethal
- o Lab Diagnosis
- Colonies are non-hemolytic and form a Medusa-head colony
- Colonies are sticky
-
B. cereus
- GPB-spore
- o Beta-hemolytic, motile, no capsule
- o Major cause of food poisoning (especially refried rice, rice loving bacteria) via enterotoxins
- o Two types of food poisoning:
- Emetic formSuperantigen, heat stable enterotoxin
- Diarrheal formA/B toxin, heat-labile enterotoxin
-
Clostridium:
- GPB gram-positive rods
- Most are motile, strictly anaerobic
- Species
- C. perfringens (Types A-E)
- C. tetani
- C. botulinum
- C. difficile
- C. septicum
-
C. perfringens
- (Types A-E)
- GPB-spore
- o Virulence Factors:
- Alpha-toxin (PLC, lecithinase) (Type A contains just this toxin)
- Beta-toxin
- Epsilon-toxin
- Iota-toxin
- Enterotoxin (heatl labile)
- o Epidemiology: Type A is responsible for most human infections in the US
- o Diseases:
- Soft-Tissue infections
- • Cellulitis with gas formation
- • Suppurtive myositis
- • Myonecrosis (gas gangrene)
- Gastroenteritis
- • Food Poisoning: caused by enterotoxin-producing Type A
- • Necrotizing enteritis (pig-bel): caused by Type C strain
- o Lab Diagnosis:
- culture on agar plate with egg yolk
- • Alpha-toxin interacts with egg yolk to produce characteristic precipitate around colonies
- Double Zone of Hemolysis: small area of beta hemoysis surrounded by large area of alpha hemolysis
- Clostridium: gram-positive rods
- GPB
- Most are motile, strictly anaerobic
-
C. tetani
- GPB-spore
- o Form spore at end like a drumstick or tennis racket
- o Causes Tetanus
- o Virulence Factors:
- Tetanospasmin (Tetanus toxin)
- • A/B toxin
- o A domain blocks the release of inhibitory neurotransmitters GABA and glycine
- o B domain binds to nerve membrane
- o Epidemiology: Spores are found most places and exposure is often, but disease is uncommon due to vaccine
- o Diseases:
- Generalized Tetanus (most common)
- • Trismus: lockjaw
- • Sardonic Smile: risus sardonicus
- • Back spasms: opisthotonos
- • Muscles Spasms
- • Systemic symptoms
- Localized tetanus
- Neonatal tetanus
- o Lab Diagnosis
- Appears as a film on agar plate, not colonies
- Clostridium: gram-positive rods
- GPB
- Most are motile, strictly anaerobic
-
C. botulinum
- GPB-spore
- o Etiologic agent of Botulism
- o Virulence Factors
- Botulinum toxin
- • Neurotoxin, A/B toxin
- o A domain inhibits release of acetylcholine leading to muscle contraction
- o Epidemiology:
- Home-canned foods, usually in asparagus, beets, and corn
- Honey
- o Diseases:
- Infant Botulism: muscle weakness and breathing problems
- Foodborne botulism: neither emetic nor diarrheal form of food poisoning (NO enterotoxin)
- • Drooping eyelids, slurred speech, difficulty swallowing
- Wound botulism
- Inhalation botulism
- o Therapeutic uses of botulism toxin
- BOTOX!
- Clostridium: gram-positive rods
- GPB
- Most are motile, strictly anaerobic
-
C. difficile
- GPB-spore
- o Virulence Factors:
- Exotoxin A: increases permeability of intestincal cell wall=diarrhea
- Exotoxin B: damages mucosa and causes pseudomembrane formation
- o Not a food-poisoning pathogen
- o Diseases:
- Exposure to antibiotics is associated with overgrowth of this and other GI diseases
- Antibiotic Associated Diarrhea (AAD)
- Clostridium: gram-positive rods
- GPB
- Most are motile, strictly anaerobic
-
C. septicum
- GPB-spore
- o Cancer associated bacteria pathogen
- o Indication of colon cancer
- o Non-spore formers
- Clostridium: gram-positive rods
- GPB
- Most are motile, strictly anaerobic
-
Listeria
- Gram-positve rods
- Motile
- Facultative anaerobe: can live inside or outside of the host cell
- Beta-hemolytic
- Species:
- L. monocytogenes
-
L. monocytogenes
- GPB, non-spore
- o Can grow at a broad temperature range and in a high salt concentration
- o Faculative intracellular pathogen
- o Causes food poisoning in refergerated and preserved foods
- Does not use enterotoxin
- o Virulence Factors:
- Ability to grow at low temps and in high salt concentrations
- Able to grow inside of macrophages
- Factors involved in intracellular growth:
- • Entry (internalins)
- • Escape from phagolysosome (listeriolysin O and PLC)
- • Multiplication
- • Assembly of actin (ActA)
- • Extrusion
- o Epidemiology: disease associated with consumption of contaminated food products, newborns and immunocompromised individuals are most at risk
- o Diseases:
- Neonatal Disease: high mortality rate, exposure on vaginal delivery
- Adult Disease: normal adults are resistant, immunosupressed people might get gastroenteritis, septicemia, meningitis
- Listeria
- Gram-positve rods
- Motile
- Facultative anaerobe: can live inside or outside of the host cell
- Beta-hemolytic
-
Corynebacterium
- GPB, non-spore
- Aerobic
- Non-motile
- Cell wall contains short chain mycolic acid (weak acid fast)
- Species:
- C. diphtheria
- o Pleomorphic bacilli (Chinese letters)
- o Lab Diagnosis:
- Metachromatic granules in cytoplasm when stained with methylene blue
- Tellurite agar plate: will see Te precipitating out
- Elek Test: tests for exotoxin either in vitro or in vivo (guinea pigs)
- o Causes diphtheria
- o Virulence factors:
- Diptheria exotoxin
- • Classic A/B toxin that binds to EF-2 to terminate translation
- • Toxin gene is carried by lysogenic bacteriophage (specialized transduction)
- o Epidemiology: Humans are the only reservoir for this bacteria
- o Diseases:
- Respiratory diphtheria: thick pseudomembrane in pharynx and bulk neck
- Cutaneous diphtheria: causes nonhealing ulcers on the skin
-
Nocardia
- GPB, non-spore
- Catalase positive
- Strict Aerobe
- Forms long branching filaments called aerial hyphae
- Partially (weakly) acid fast
- Species:
- • N. asteroids
- o Virulence factors:
- Cord factor: antiphagocytic
- o Epidemiology: acquired by inhalation (pulmonary) or traumatic introduction (cutaneous)
- o Diseases:
- Brain abscesses are most common
-
Actinomyces
- GPB, non-spore
- Catalase negative, Facultative anaerobic
- Form aerial hyphae
- NOT Acid Fast
- Diseases:
- • Chronic suppurative and granulomatous disease of face, thorax or abdominal areas
- Lab diagnosis: sulfur granules found in pus from lesions
-
Propionibacterium
- GPB, non-spore
- Anaerobic
- Produces propinonic acid as a byproduct of fermentation
- Species:
- • P. acnes
- o Most prevalent organism in the follicular flora, responsible for at least 90% of acne cases
- o Virulence factors: all invasins
- Lipases
- Proteases
- Neuraminidase
- Hyaluronidase
-
Neisseria
- GNC
- Diplococci, kidney, coffee bean shaped bacteria
- Aerobic
- Fastidious (require complex growth media)
- Non-motile
- Species:
- N. gonorrhoeae
- N. meningitidis (meningococcus)
-
N. gonorrhoeae (gonococcus)
- • Fimbriae play a major role in adherence
- o Only fimbriated cells are virulent
- • A variety of outer membrane proteins
- o Opa: opacity protein, mediates firm attachment to host cells
- o Por
- o Rmp
- o LOS: similar to LPS, but doesn’t have O-antigen chain
- • Non-capsulated
- • Epidemiology: higher risk of disease in patients with definiciences in late components of complement (C5-C9 proteins)
- • Diseases:
- o Gonorrhea
- Characterized by purulent discharge at involved site
- Second most commonly reported bacterial STD in the US
- o Ophthalmia neonatorum
- o Disseminated infections: spread of infection from genitourinary tract through blood to skin or joints
- • Lab Diagnosis:
- o Thayer-Martin Agar: inhibits growth of most other organisms except Neisserias
- Contains: Vancomycin (kills all gram positive organisms), Colistin (kills all gram negative organisms except Neisseria), Nystatin (kills all fungi)
- Neisseria
- GNC
- Diplococci, kidney, coffee bean shaped bacteria
- Aerobic
- Fastidious (require complex growth media)
- Non-motile
-
N. meningitidis (meningococcus)
- • Has a polysaccharide capsule (antiphagocytic)
- • Epidemiology: humans are the only natural hosts
- o Highest incidence in children younger than 5
- • Diseases:
- o Meningococcal meningitisBaby Killer
- Second most common cause of meningitis
- o Meningococcemia: results in amputation of legs and arms
- • Lab Diagnosis:
- o Cerebrospinal fluid
- o Thayer-Martin Agar
- Neisseria
- GNC
- Diplococci, kidney, coffee bean shaped bacteria
- Aerobic
- Fastidious (require complex growth media)
- Non-motile
-
E. coli
- • Motile and lactose fermentor
- • Over 700 antigenic types recognized based on the three antigens
- • Virulence factors:
- o Adhesins
- o Exotoxins:
- Shiga toxins (A/B toxin)• Interacts with ribosomes to inhibit protein synthesis• Causes hemolytic uremic syndrome
- Shiga-like toxins (A/B toxin)Heat-labile enterotoxins (LT) (A/B toxin)
- Heat-stable enterotoxins (ST)superantigen
- Hemolysinforms pores in cell membrane of blood cells
- • Epidemiology:
- o Most common aerobic, gram- rods in the GI tract
- o Important nosocomial pathogen
- o Generally acquired exogenously in contaminated food and water, causes food poisoning
- • Diseases:
- o Extra-intestinal diseases:
- UTI
- Septicemia
- Neonatal meningitis
- Baby killer
- o Intestinal Diseases (diarrhea)
- 5 different pathogenic groups cause gastroenteritis
- • ETEC: Enterotoxigenic E. colio Non-invasive, secretes heat labile and or heat stable toxinso Causes traveler’s diarrhea
- • EAEC: Enteroaggregative E. colio Non-invasive, secretes heat stable-like toxin and hemolysin
- • EPEC: Enteropathogenic E. colio Moderately invasive, works by the “attaching-effacing” mechanism that results in osmotic diarrheao Symptoms result mainly from invasion rather than toxigenesis
- • EHEC: Enterohemorrhagic E. Colio Moderately invasive, secretes shiga toxin in addition to “attaching-effacing” mechanismo May complicate pediatric diarrhea with hemolytic uremia syndromeo E. coli O157:H7most common form of E. coli in the US
- • EIEC: Enteroinvasive E. colio Invasive, facultative intracellular pathogeno Uses Type III secretion systemo Causes dysentery-like diarrhea and is potentially fatal
-
Enterobacteriaceae Family
- Escherichia coli
- Salmonella
- Shigella
- Yersinia
- Klebsiella
- Proteus
- GNB
- o Common Characteristics:
- Facultative anaerobes
- Catalase positive and oxidase negative
- Share a common antigen: enterobacterial common antigen
- Serologic classification of this family with three major groups of antigens
- • Capsule (K antigen)
- • Flagellar (H antigen)
- • Somatic O polysaccharide (O antigen)part of LPS
- Ability to ferment lactose or not and ability to be motile or not further subdivide this family
-
ETEC: Enterotoxigenic E. coli
- gastroenteritis
- o Non-invasive, secretes heat labile and or heat stable toxins
- o Causes traveler’s diarrhea
-
EAEC: Enteroaggregative E. coli
- gastroenteritis
- o Non-invasive, secretes heat stable-like toxin and hemolysin
-
EPEC: Enteropathogenic E. coli
- gastroenteritis
- o Moderately invasive, works by the “attaching-effacing” mechanism that results in osmotic diarrhea
- o Symptoms result mainly from invasion rather than toxigenesis
-
EHEC: Enterohemorrhagic E. Coli
- gastroenteritis
- o Moderately invasive, secretes shiga toxin in addition to “attaching-effacing” mechanism
- o May complicate pediatric diarrhea with hemolytic uremia syndrome
- o E. coli O157:H7most common form of E. coli in the US
-
EIEC: Enteroinvasive E. coli
- gastroenteritis
- o Invasive, facultative intracellular pathogen
- o Uses Type III secretion system
- o Causes dysentery-like diarrhea and is potentially fatal
-
Salmonella
- GNB
- • Motile, non-lactose fermenter
- • Facultative intracellular pathogens
- • Resistant to bile acids
- • Virulence factors:
- o Tolerant to acids in stomach
- o Intracellular growth ability
- o Heat-labile enterotoxin
- • Epidemiology: primary pathogen (always associated with disease)
- o Carried by reptiles and contaminated food products
- o S. typhi is strict human pathogen
- o S. enteritidis can be found in eggs and pet reptiles
- • Diseases: Salmonellosis
- o Enteric Fever (Typhoid Fever)
- Caused by S. typhi
- Usually includes a high fever
- o Enteritis (acute gastroenteritis)
- Caused by ingestion of infected food or the organisms
- • Lab Diagnosis: stool specimen required
-
Shigella
- GNB
- • Non-motile, non-lactose fermentor
- • Resistant to bile acids
- • Facultative intracellular pathogen
- • S. Dysenteriae causes the most serious diseases
- • Virulence factors:
- o Intracellular growth ability
- o Shiga toxin: A/B toxin that inhibits protein synthesis and has enterotoxin effect (blocks absorption of electrolytes)
- • Epidemiology: transmitted via the fecal-oral route and it is highly infectious
- • Diseases:
- o Shigellosis (bacillary dysentery)
- Severe diarrhea with blood
-
Yersinia
- GNB
- • Motile, non-lactose fermenter
- • Facultative intracellular pathogen
- • Can grow at 1-4 degrees C
- • Virulence Factors:
- o Type III secretion system: mediate resistance to phagocytic killing
- Syringe-like mechanism allows them to inject virulence factors into host cells
- • Epidemiology: Primary pathogen
- o Y. pestis is a zoonotic infection
- o Y. enterocolitica is acquired by eating contaminanted food especially raw or undercooked pork
- • Diseases:
- o Bubonic Plaque (black death)
- Caused by Y. pestis
- o Gastroenteritis
- Caused by Y. enterocolitica
-
Klebsiella
- GNB
- • Non-motile and non lactose fermentor
- • K. pneumoniae is the most common cause of pneumonia especially in malnourished alcoholics
- o Also a frequent UTI pathogen
-
Proteus
- GNB
- • Motile and non-lactose fermenter
- • Forms swarming colonies
- • P. mirabilis: most common and causes UTI
- o Produces large quantities of urease and causes stones in UT and/or kidneys
-
Vibrio
- o Common Characteristics:
- Facultative anaerobes
- Oxidase positive
- Broad range of ideal temperatures (14-40 degrees C)
- Very sensitive to acidic environments
- o Species:
- V. cholera
- V. parahaemolyticus
- V. vulnificus
-
V. cholera
- • Does not require salt for growth, but can tolerate it
- • Etiology of cholera
- • Virulence factors:
- o Cholera enterotoxin (CtxA, CtxB)identical to heat labile A/B toxin
- Increases cAMP
- Causes watery diarrhea
- • Epidemiology: disease is rare because infectious dose is high-(most organisms are killed by stomach acids)
- o Transmitted by contaminated food or water
- • Disease:
- o “rice-water stool”
- o Death caused by dehydration
- Vibrio
- o Common Characteristics:
- Facultative anaerobes
- Oxidase positive
- Broad range of ideal temperatures (14-40 degrees C)
- Very sensitive to acidic environments
-
V. parahaemolyticus
- GNB
- • Ingestion of undercooked shellfish or raw oysters
- • Usually a self-limiting illness
- Vibrio
- o Common Characteristics:
- Facultative anaerobes
- Oxidase positive
- Broad range of ideal temperatures (14-40 degrees C)
- Very sensitive to acidic environments
-
V. vulnificus
- GNB
- • Exposure of wounds to sea water=wound infections
- • Salt-lover (halophillic)
- Vibrio
- o Common Characteristics:
- Facultative anaerobes
- Oxidase positive
- Broad range of ideal temperatures (14-40 degrees C)
- Very sensitive to acidic environments
-
Campylobacter
- GNB
- o Species:
- C. jejuni
- • Hippurase positive
- • Grows at higher temperatures (42 degrees C)
- • Leading cause of bacterial gastroenteritis in the US
-
Helicobacter
- GNB
- o Species:
- H. pylori
- Dr. Marshall
- • Urease positive
- • Microaerophilic
- • Colonizes stomach at low pH
- • Virulence factors:
- o Flagella
- o Mucinase
- o Ureasefor pH maintenance
- o Superoxide dismutase
- o Catalase
- • Epidemiology: humans are the primary reservoir
- o Most common chronic bacterial infection of humans (present in half of world population)
- • Diseases:
- o Gastritis
- o Duodenal and gastric ulcers
- o Gastric adenocarcinomas (Cancer-associated bacteria)
- • Lab Diagnosis:
- o Urease test
- o Carbon-14 Urea breath test
- o Blood test (antibody detection)
-
Haemophilus
- GNB
- o Non-motile
- o Aerobic or facultative anaerobic
- o Species:
- H. influenzae
- • Typed by capsular polysaccharide with capsule swelling test
- • H. influenzae type B (Hib) clinically most virulent (responsible for 95% of disease)
- • Virulence factors
- o Polysaccharide capsule type B (major virulence factor of Hib)
- Contains polyribitol phosphate (PRP)
- o Immunoglobulin (Ig) A1 proteases
- • Epidemiology: Hib is an uncommon member of normal flora
- o BUT, H. influenzae constitutes 10% of flora in saliva
- • Disease:
- o Infants and young children mostly affected by Hib if not vaccinated
- Active immunization with conjugated PRP
- –epiglottitis
- –meningitis
- baby killer!
- • Lab diagnosis: NAD+ (factor V) and hemin (factor X) required for growth
- H. ducreyi
- • Causes STD, chancroid, like gonorrhea, but no discharge
-
Legionella
- GNB
- o L. pneumophila
- Aerobic gram negative rod bacteria
- Non-capsulated and motile
- Facultative intracellular pathogen
- Main hosts are amoeba and human macrophages
- Virulence Factors:
- • Produce beta-lactamase
- Epidemiology:
- • Outbreaks of the disease are often correlated with the presence of amoebas because legionella form symbiotic relationships with them
- • No person-to-person transmission
- Diseases: (Legionellosis)
- • primarily affect the lung
- • Legionnaire’s disease: severe form of pneumonia
- • Pontiac Fever: non-pneumonic illness, an influenza-like illness, self-limiting
- Lab Diagnosis:
- • BCYE agar containing L-cysteine
-
Pasteurella Multocida
- GNB
- o Normal flora in oropharynx of animals
- o True zoonotic infection
-
Bartonella henselae
- GNB
- o Cat-scratch disease
- o True zoonotic infection
-
Bordetella, Brucella, Francisella
- o Extremely small
- o Bordtella
-
B. pertussis:
- GNB
- Bordtella
- causes pertussis (whooping cough)
- • Noninvasive infection of ciliated respiratory epithelial cells
- • Virulence Factors:
- o Adhesins: Filamentous hemagglutinin (FHA) and Pertussis toxin (A/B toxin)
- o Toxins: Pertussis toxin and Adenylate cyclase/hemolysin toxin (A/B toxin)does NOT cause bacteremia
- Pertussis toxin increases [cAMP], which increases respiratory secretions and mucus production
- • Epidemiology:
- o Person-to-person spread
- o Non-vaccinated individuals at greatest risk (DPT vaccine)
- • Lab Diagnosis: Bordet and Gengou (BG) agar
- B. parapertussis: causes milder form of pertussis
- B. bronchiseptica: causes bronchopulmonary disease
-
Brucella:
- GNB
- True zoonotic disease
- Facultative intracellular pathogen
- Diseases: Brucellosis (undulant fever or Malta fever)
- Antibiotics (tetracycline)
-
Francisella
- GNB
- F. tularensis:
- • Facultative intracellular pathogen of macrophages
- • Diseases: Causes Rabbit Fever (Tularemia)
- o Ulceroglandular tularemia
- o Oculoglandular tularemia
- o Pneumonic tularemia
- • Virulence Factors:
- o Antiphagocytic capsule
- o Intracellular growth ability
- • True zoonotic infection
- o Rabbits
- o Hard Ticks
- • Lab Diagnosis: BCYE agar containing L-cysteine
-
Pseudomonas aeruginosa
- GNB
- o The most important opportunistic pathogen of immunocompromised individuals
- o Obligate aerobe
- o Virulence factors:
- Slime layer: mucoid exopolysaccaride or alginate coat)
- Antibiotic resistance (β-lacatamase)
- Pseudomonas Exotoxin A
- • Binds to EF-2 (A/B toxin)like diphtheria toxin
- o Epidemiology:
- Nosocomial pathogen
- Fatality rate is 50%
- o Diseases:
- Primary skin infections
- • Burn infection
- • Hot-tub rash
- Ear infections: “swimmer’s ear”
- Eye infections: contaminated contact lens cleansing fluids
- Pulmonary infections
- Urinary tract infections
- Bacteremia
- o Lab Diagnosis: Culture Characterisits
- Grape-like odor
- Produce a variety of pigments
- Ability to grow at 42 degrees C
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