BioSci: Bacteriology II

Human pathogens, gram positive cocci (3)

• Streptococcus pyrogenes

• Staphylococcus aureus

• Streptococcus pneumoniae

Human pathogens, gram positive rods (5)

• Clostridium

• Bacillus

• Gardnerella

• Listeria

• Corynebacterium

Human pathogens, gram negative cocci

• Neisseria (both)

Human pathogens, gram negative rods (20)

• E. coli

• Salmonella

• Shigella

• Vibrio

• Campylobacter

• Helicobacter

• Klebsiella-Enterobacter-Serratia group

• Proteus-Providencia-Morganella group

• Pseudomonas

• Bacteroides

• Prevotella

• Fusobacterium

• Haemophilus

• Legionella

• Bordetella

• Brucella

• Francisella

• Pasteurella

• Yersinia

• Bartonella

Human pathogens, acid fast (2)

• Mycobacteria

• atypical Mycobacteria

Human pathogens, spirochetes (2)

• Treponema

• Borrelia

Human pathogens, intracellular (3)

• Chlamydia

• Rickettsia

• Anaplasma

Human pathogens, pleiomorphic

Mycoplasmas

Streptococcus pyrogenes

Group:

Type:

Virulence:

Transmission:

Tx?:

Group: Strep A

Type: Gram + cocci in chains

Virulence: causes complete lysis of RBCs

Transmission: normal flora of human oropharynx and skin

Tx?: No vaccine

Streptococcus pyrogens - virulence factors in depth

• pili, capsule, glycocalyx, enzymes, toxins

Pili = pili made of M proteins, adheres to pharyngeal epithelium; antibodies against M protein can cross-react with our cardiac myosin

Capsule = resists phagocytosis

Glycocalyx = adheres strongly to endothelium of heart valves

Enzymes = degrade human tissue (collagenase, streptokinase)

Toxins =

• Exotoxin B = rapidly destroys tissue

• Hemolysins = streptolysin O and A cause beta-hemolysis of phagocytes; O also indicates infection

Streptococcus pyrogens - symptoms

• Strep throat

• acute rheumatic fever

• necrotizing fasciitis

• Most common cause of cellulitis, also cause impetigo, erysipelas, scarlet fever, streptococcal toxin shock syndrome

• if gets into bloodstream, can cause endocarditis

Erysipelas is

a superficial skin infection, also known as St. Anthony's fire, that causes a bright red, swollen, and painful rash with well-defined borders, typically on the face or legs

Strep throat symptoms

• severe exudative pharyngitis (yellow or white exudates on tonsils)

• fever

• painful cervical lymphadenopathy

Rheumatic fever symptoms

form a couple weeks after untreated pharyngitis = NOT actively infected, a complication following infection

• can cause reactive migratory polyarthritis with red/hot/swollen joints

• myocarditis, endocarditis = damaging aortic and mitral valves

• rash

• fever

• chorea

• glomerulonephritis

How does rheumatic fever affect joints, heart, brain, and kidney

antibodies made to strep’s M protein cross-react..

• joints = arthritis

• heart = carditis

• brain tissue = chorea

• kidneys = glomerulonephritis

Necrotizing fasciitis symptoms

leads to tissue death; usually has to be opened up and washed out operatively - not uncommon for patients affected to end up losing affected limb

Staphylococcus aureus

Group:

Type:

Virulence:

Transmission:

Tx?:

Group:

Type: gram positive cocci in clusters

Virulence: gram positive, coagulase positive, beta hemolytic

Transmission: part of normal flora with nose = main site of colonization; also skin

• fomite sources = towels and clothing

• breast milk and vaginal flora (~5%)

Tx?: no vaccine

Staph. epidermidis and Staph. saprophyticus

do not have ____

coagulase; also do not ferment mannitol and do beta hemolysis

Staphylococcus aureus - virulence factors

• capsule, peptidoglycan, catalase, coagulase, hemolysins

Capsule: evades immune system; poorly immunogenic, poor vaccine responses

Peptidoglycan: has endotoxin-like properties to cause septic shock; teichoic acid

Catalase: degrades H202 in phagolysomes of phagocytes = enhance survival

Coagulase: causes plasma to clot; prothrombin to thrombin

Hemolysins: hemolyze RBCs to acquire iron for growth

Staphylococcus aureus - virulence factors, toxins

Toxins:

• Entertoxin: acts as super antigen; causes prominent vomiting, watery diarrhea; resistant to heat, stomach enzymes and acids

• Toxic Shock Syndrom Toxin: causes septic shock, up to 25% of strains

• Exfoliatin: protease that causes separation of epidermis; scalded skin syndrome and bullous impetigo

Chorea

a neurological movement disorder characterized by involuntary, rapid, jerky, and unpredictable movements that can affect various parts of the body, including the face, limbs, and trunk; complication of rheumatic fever

Staphylococcus aureus - virulence factors, antibiotic resistance

Beta lactase: degrades beta lactam abx like penicillin; 90% of S. aureus, encoded by plasmids

PBP mutations: resistant to beta lactamase resistant abx such as methicillin and nafcilllin = MRSA

• most common cause of skin abscesses

• can cause pneumonia, necrotizing fasciitis, sepsis in immunocompetent patienst

• may strains have this = 50% of hospital isolated strains

Vancomycin resistant cassete: encoded in transposon on plasmids = VRSA

Just because you see septic shock does not mean it is caused by ____, it can also be caused by ____

a gram negative microbe, gram positive microbe such as Staphylococcus aureus

Staphylococcus aureus - symptoms

Causes pus-forming skin/soft tissue infections (erythematous, hot, painful, swollen), food poisoning, scalded skin syndrome, and toxic shock.

• Cellulitis = firm (indurated)

• Abscesses = squishy (fluctuant), may drain pus

• Can spread to bloodstream (sepsis) or nearby tissues

Also common cause of hospital-acquired pneumonia, septicemia, surgical wound infections and bacterial conjunctivitis

Staphylococcus aureus - abscess treatment

• incision and drainage; + / - Abx

• muciproxin ointment to reduce nasal colonization -or

• chlorhexidine showers to reduce skin colonization

Staphylococcus aureus can also cause ____ (3)

• food poisoning (gastroenteritis); from ingestion of enterotoxin, short incubation time 1-8 hours, vomiting > diarrhea

• scalded skin syndrome: fever, large bull, erythematous macular rash that desquamates; electrolyte imbalances can occur due to fluid losses = young children

• toxic shock syndrome: fever, hypotension, diffuse sun-burn like rash that desquamates; multi-organ system involvement

Clostridium tetani

Group:

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Tx?:

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Type: anaerobic gram positive bacilli; spore forming

Virulence: spore forming

Transmission: soil source of spores entering wound, enter skin; spores germinate in necrotic tissue with poor blood supply

Tx?: vaccine against tetanus toxoid and antitoxin available; booster every 10 years

Clostridium tetani spores look like

tennis rackets

Clostridium tetani - virulence factors

tetanus toxin: blocks release of inhibitory neurotransmitters glycine and GABA

• leads to excitatory neurons that are unopposed

• toxin travels from wound to axons or via bloodstream to spinal cord

Clostridium tetani - symptoms

muscle spasms and spastic paralysis

• lock jaw and neck muscles (trismus) are most prominent

• grimace, opisthotonos (arching of back), hyperreflexia, and eventually respiratory failure

Clostridium botulinum

Group:

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Virulence:

Transmission:

Tx?:

Group:

Type: gram positive bacilli

Virulence: spores, toxin

Transmission: ingestion of improperly sterilized canned food in non-acid environment

Tx?: antitoxin available, no vaccine

Clostridium botulinum - triggers for spore germination

soil = main reservoir for spores, on vegetables (corn, asparagus, potatoes, beans, smoked fish, etc)

• bacteria remains in spores in acidic environments and are heat resistant up to 115C, toxin is heat-labile

• **requires neutral pH, warm, anaerobic environment to germinate and become active + toxic

Clostridium botulinum - modes of transmission, infant botulism

if infants are given honey containing botulinum spores, can germinate inside of infants because it is a favorable environment = infant stomach acid pH is not acidic enough, less normal flora and have immature immune systems (lack IgA)

• ** no honey for infants before 1 y/o age

Clostridium botulinum - virulence factors, botulinum toxin

acts at the neuromuscular junction to block release of acetylcholine, causes weakness and descending paralysis

• one of the most toxic compounds known, super low LD50

• toxin is encoded on plasmids in bacterial genome/by bacteriophages

• toxin travels from mucose in GI tract to bloodstream to peripheral nerves

Clostridium botulinum - signs/symptoms

descending weakness and flaccid paralysis

• diplopia, dysphagia, ptosis, eventual respiratory muscle failure

Clostridium botulinum - infant botulism

• hypotonia

• weakness

• respiratory problems, can recover spontaneously

Clostridium botulinum - wound botulism

spores contaminate a wound, germinate, and produce toxin at site

Clostridium perfringens

Group:

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Virulence:

Transmission:

Tx?:

Group:

Type: anaerobic gram positive bacilli that form spores

Virulence: spore forming,

Transmission: normal flora of colon and vagina (in non-spore/vegetative form), can enter skin via wounds, ingestion of contaminated food with heat-resistant spores located in soil

Tx?: no vaccine

Clostridium perfringens - virulence factors

alpha toxin: damages cell membranes leading to hemolysis and necrosis, aka lecithinase

enterotoxin: causes diarrhea, aka superantigen

other degradative enzymes produce hydrogen gas in tissues = results in crepitus felt

Clostridium perfringens - gas gangrene

= necrotizing fasciitis or myonecrosis

• war wounds, automobile/motorcycle accidents, and septic abortions (endometriosis)

• high mortality rates

Tx = incision and drainage, Abx needed

Clostridium perfringens - food poisoning

grow rapidly in reheated meat dishes

S/S: watery diarrhea with cramping, little vomiting

• resolves in 24 hours on its own

Clostridium difficile

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Virulence:

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Type: anaerobic gram positive bacilli

Virulence: spore forming

Transmission: part of normal flora (3%) that can overgrow after Abx (clindamycin) administration; can also be transmitted fecal-oral route

Tx?: no vaccine, can do fecal transplants to outcompete with normal flora

Clostridium difficile - virulence factors

Exotoxin A: causes watery diarrhea

Exotoxin B: causes apoptosis of mucosal cells and leads to pseudomembrane formation

• thick, adherent, white/yellowish plaques on mucosal surface of colon

• disaggregation of actin cytoskeleton

Both exotoxins inactivate GTPases by glycosylation

Hypervirulent strain with more severe disease, more recurrences, and more resistant to metronidazole and fluoroquinolone

Clostridium difficile causes pseudombranous colitis, which consists of ___

non-bloody diarrhea, fever, and abdominal pain

• stool has many neutrophils

• toxic megacolon can occur

Bacillus anthracis

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Virulence:

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Group:

Type: gram positive bacilli in chains

Virulence: spore forming

Transmission: spores are located in soil or found on animals; enter through breaks in skin or via inflation; can also be ingested via contaminated meat = spores germinate once inside body

Tx?: vaccine available, mAb to protective antigen for those at risk

Bacillus anthracis - virulence factors

Capsule: resists phagocytosis, made of D-glutamate

Anthrax toxin has 3 components

• Protective antigen: makes pore in cell membranes to allow lethal factor and edema factor inside cell; antibodies against this protect again disease

• Lethal factor: exotoxin protease that causes necrosis via inhibitation of MAP kinase pathway; induces apoptosis

• Edema factor: exotoxin that causes edema; increases cAMP in cells = outpouring of intracellular fluid into spaces

What abx can increase risk for C diff infection?

Clindamycin

Bacillus anthracis causes ____ which has cutaneous, pulmonary, and gastrointestinal components

anthrax

Anthrax cutaneous effects

painless necrotic (black eschar) lesions called malignant pustules with significant edema; can progress to bacteremia and death

Anthrax pulmonary effects

after inhalation, moves to mediastinal lymph nodes and causes hemorrhagic mediastinitis

• “Wool-sorter’s disease”

• not transmissible to others

• can lead to septic shock and death

Anthrax gastrointestinal effects

vomiting, bloody diarrhea, abdominal pain

Bacillus cereus

Group:

Type:

Virulence:

Transmission:

Tx?:

Group:

Type: gram positive bacilli

Virulence: spore forming

Transmission: spores on grains, can survive high heat, germinate when reheated/kept warm for a long time, ingested

Tx?: no vaccine

Bacillus cereus - enterotoxin

causes watery diarrhea and gastroenteritis

• short incubation time, ~4 hrs = N/V

• long incubation time, ~18 hrs

Gardnerella vaginalis

Group:

Type:

Virulence:

Transmission:

Tx?:

Group:

Type: gram positive bacilli; cell wall is thinner than typical gram positive so it loses color and can appear pink

Virulence:

Transmission: part of normal flora; in dysbiosis = replace Lactobacillus, pH >4.5 suggests this

Tx?: no vaccine

Gardnerella vaginalis - symptoms

bacterial vaginosis: white/gray malodorous “fishy” discharge

• most common vaginal infection in sexually active women

• no inflammation so not a vaginitis but can be mild itching/irritating

• see “clue cells”; epithelial cells covered with bacteria

• higher incidence of pre-term deliveries

Chlamydia trachomatis

Group:

Type:

Virulence:

Transmission:

Tx?:

Group:

Type: obligate intracellular bacteria with cell walls that resemble gram neg

Virulence: extracellular, metabolically inert “sporelike” elementary body = reorganizes into larger metabolically active reticulate body

Transmission: reticulate body forms daughter cells by binary fission = back into elementary bodies, released from cell; site of replication inside cell is inclusion body; can see with Giemsa stains

• direct sexual contact or through birth canal

Tx?: vaccine in trials

Chlamydia trachomatis - mode of transmission

direct sexual contact or birth via vaginal canal

• enters GU tract, conjunctiva, respiratory tract

• infects epithelial cells of mucous membranes or lungs

• usually co-infection with N. gonorrhea

Chlamydia trachomatis - symptoms (urethritis, cervicitis)

• can be asymptomatic

• causes urethrititis: clear, mucoid urethral discharge in males = can progress to epididymitis, prostatitis, proctitis

• causes cervicitis: purulent vaginal discharge and intermenstrual bleeding in females= lead to PID with severe suprapubic pain from fallopian tube infections; sterility or ectopic pregnancies from tube scarring

Chlamydia trachomatis -symptoms cont. (lymphogranuloma venereum)

• lymphogranuloma venereum: lesions on genitalia and lymphadenopathy

Chlamydia trachomatis - symptoms (cont), conjunctivitis, pneumonia, Reiter’s syndrome

• pneumonia

• conjunctivitis = non-purulent discharge, can lead to blindness, can infect neonates while passing through birth canal

• Reiter’s Syndrome = uveitis, urethritis, arthritis: from anitbodies cross-reacting with antigens of cells in those areas = can’t see, can’t pee, can’t climb up a tree

Neisseria gonnorhoeae

Group:

Type:

Virulence:

Transmission:

Tx?:

Group:

Type: gram negative diplococci = pairs look like kidney beans

Virulence: pili, endotoxin, protease, penicillinase

Transmission: direct contact, sexual or passage through birth canal

Tx?: no vaccine

Neisseria gonnorhoeae - virulence factors = pili, endotoxin, protease, penicillinase

Pili = attach to urinary tract epithelium and resist phagocytosis

Lipo-oligosaccharide endotoxin

IgA protease: degrades IgA antibodies allowing bacteria to adhere to mucous membranes

Penicillinase: degrades penicillin

Neisseria gonnorhoeae - symptoms

• urethritis/epididymitis

• cervicitis

• conjunctivitis

• anorectal infections

• pharyngitis

• can have disseminated infections in immunocompromised individuals (bacteremia) that manifest as arthritis, tenosynovitis or pustules in skin

Neisseria meningitides

Group:

Type:

Virulence:

Transmission:

Tx?:

Group:

Type: gram negative diplococci, in pairs

Virulence: polysacc capsule, endotoxin, IgA protease, factor H binding protein, antibiotic resistance

Transmission: airborne droplets that enter nasopharynx, enter bloodstream, disperses to meninges and joints

Tx?: vaccine available

Neisseria meningitides - virulence factors = capsule, endotoxin, BP, abx resistance

Polysaccharide capsule: resists phagocytosis

Lipo-oligosaccharide endotoxin: causes fever and shock

Factor H binding protein: inhibits complement

Abx resistance: PCN, sulfonamides, ciprofloxacin

Neisseria meningitides - symptoms

• meningococcemia = high fever, hypotension, and petechia/purpura

  • can lead to DIR and adrenal insufficiency

Treponema pallidum

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Tx?:

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Type: motile spirochetes

Virulence: grows very slowly; antibiotic resistance = azithromycin

Transmission: direct contact with skin or mucous, crosses placenta and can infect fetus, rarely be bloodborne

Tx?: no vaccine

Treponema pallidum - symptoms (primary, secondary, tertiary syphilis)

primary syphilis: contender ulcers (chancres) then spreads to bloodstream

secondary syphilis: maculopapular rash on palms and soles; moist papules on skin and mucous membranes (condylomata lata on genitalia)

tertiary syphilis: granulomas (gummas) of skin and bones

• “neurosyphilis” = CNS and PNS demyelination (general paresis = paralysis and dementia, tabes dorsals = loss of coordination)

• cardiovascular lesions = aortitis or ascending aortic aneurysm

Can remain latent for years

Syphilis can also be ____ via the placenta

congenital

Congenital syphilis symptoms

Skin/bone lesions: Hutchinson’s teeth, mulberry molars, saber shins, saddle nose, rhagades (fissures at angle of mouth/nose) and frontal bossing

Also cause hepatosplenomegaly, interstitial keratitis, snuffles, deafness, stillbirth

Haemophilus ducreyi

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Virulence:

Transmission:

Tx?:

Group:

Type: gram negative bacillus

Virulence: penicillinase = degrades PCN

Transmission: sexually transmitted

Tx?: no vaccine

Haemophilus ducreyi - S/S

causes chancroid (soft chancre); painful penile lesions, non-indurated (soft) ulcers, local lymphadenitis (bubo)

common in tropical countries

Corynebacterium diphtheria

Group:

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Virulence:

Transmission:

Tx?:

Group:

Type: gram positive bacilli (club shaped in V or L formation)

Virulence: diphtheria toxin

Transmission: airborne droplets = infect URT and broken skin

Tx?: toxoid vaccine and antitoxins available (Balto, Togo, need boosters every 10 years)

Corynebacterium diphtheria - diphtheria toxin

carried by bacteriophage; causes cell death and leads to pseudomembrane formation in pharynx and inside heart

• thick, adherent, grayish/yellowish exudates on mucosal surface of throat

Toxin transcription is inhibited by iron

Corynebacterium diphtheria - S/S

causes diphtheria = thick grayish pseudomembrane on tonsils and throat, fever, pharyngitis, and cervical lymphadenopathy

• pseudomembrane = extends into larynx and trachea causing airway obstruction

• Myocarditis and endocarditis with arrhythmias and circulatory collapse

• nerve palsies or paralysis of cranial nerves and peripheral neuritis of extremities

Haemophilus influenzae

Group:

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Virulence:

Transmission:

Tx?:

Group:

Type: gram negative bacilli

Virulence: capsule, protease, endotoxin

Transmission: airborne droplets = can have asymptomatic colonization, infects upper and lower respiratory tract, can spread via blood stream to meninges

Tx?: vaccine available

Haemophilus influenzae - virulence factors

polysaccharide capsule: resists phagocytosis

IgA protease

LPS endotoxin

Haemophilus influenzae - S/S

causes URIs, meningitis, and sepsis in young children

• most common cause of epiglottis

• causes pneumonia in adults with lung disease (COPD)

Bordetella pertussis

c

Group:

Type: gram negative coccobacilli

Virulence: capsule, pili, pertussis toxin, tracheal cytotoxin

Transmission: airborne droplets = infects URT

Tx?: vaccine available = acellular pertussis or “aP” of DTaP or TDaP!

Bordetella pertussis - virulence factors (capsule, pili, pertussis toxin, tracheal cytotoxin)

Capsule = resists phagocytosis

Pili = attach to respiratory epithelium

Pertussis toxin = causes edema in mucose which leads to severe cough

Tracheal cytotoxin = part of peptidogylcan that damages ciliated cells in respiratory tract

• LPS endotoxin works with to kill cells

Bordetella pertussis - S/S

causes whooping cough: acute tracheobronchitis

• mild URi symptoms, then severe paroxysmal cough

  • lasts 1-4 weeks “100 day cough”

  • hacking productive cough, “whoop” on inspiration, post-tussive emesis

• Can lead to pneumonia and even progress to death

Legionella pneumophila

Group:

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Transmission:

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Type: gram negative bacilli with flagella (motile!;) replicate inside amebae which help ensure survival

Virulence: endotoxin, catalase, biofilm, beta lactase

Transmission: inhalation of aerosolized contamination environmental water sources (air conditioners, water-cooling towers, hot tubs)

Tx?: no vaccine

Legionella pneumophila - virulence factors (endotoxin, catalase, biofilm, beta lactase)

LPS endotoxin

Catalase: resist destruction in phagolysosomes

Biofilm formation

B-lactamase: degrades PCNs

Legionella pneumophila - S/S

causes Legionnaire’s disease: atypical pneumonia with confusion, diarrhea, and acute kidney injury

• can get sepsis, espeically if immunocompromised

• also Pontiac fever: flu-like illness that is less severe with no pneumonia

Legionella pneumophila is killed by __

hyperchlorination and high temps

Streptococcus pneumoniae

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Virulence:

Transmission:

Tx?:

Group:

Type: gram positive diplococci or short chains of cocci

Virulence: alpha hemolytic = incomplete lysis of RBCs

Transmission: normal flora of oropharynx, that enter respiratory tract

Tx?: vaccines available, provide at least 5 year immunity; targets capsule polysaccharides

Streptococcus pneumoniae - virulence factors

capsule = evade phagocytosis

lipoteichoic acid (LTA) = causes septic shock

IgA protease

Pneumolysin = causes alpha hemolysis (partial lysis of RBCs)

PBP mutations = resistance development

Streptococcus pneumoniae - pneumonia etiology

invades alveoli causing outpouring of fluid, RBCs, and WBCs

• see fever, cough with red/rusty brown sputum and pleuritic pain

• common cause = CAP

Streptococcus pneumoniae is the most common cause of

bacteremia in asplenic patients

Streptococcus pneumoniae also causes

otitis media, sinusitis, mastoiditis, meningitis

pseudomonas aeruginosa

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Group:

Type: gram negative bacilli; blue-green pigmented + fruity odor (grapes?)

Virulence:

Transmission: mainly in soil and water, can be part of intestinal flora; contamination of respiratory therapy and anesthesia equipment, IV fluids, distilled water, tap water

Tx?: no vaccine

pseudomonas aeruginosa - virulence factors (biofilm, endotoxin, secretion system, elastase, protease, resistances)

Glycocalyx biofilm formation = especially in cystic fibrosis and burn patients

LPS endotoxin = septic shock

Type III secretion system (injectosome) = injects exotoxins directly into cell which avoids antibody response (exotoxin A)

Elastase and proteases: enzymes that facilitate invasion of organism into bloodstream

Abx + disinfectant resistances

pseudomonas aeruginosa is a ____ pathogen

opportunistic

pseudomonas aeruginosa causes

sepsis (can lead to ecthyma gangrenosum), pneumonia, chronic wounds, UTIs, malignant otitis externa

pseudomonas aeruginosa can also causes disease in immunocompromised patients if it gets in the wrong place, such as ___

hot tubs and swimming pool folliculitis, corneal infections in contact lens users, osteochondritis of foot from puncture wounds through soles of gym shoes

klebsiella pneumoniae

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Group:

Type: facultative anaerobic gram negative bacilli; nitrate reducers to nitrite

Virulence: endotoxin, capsule, beta lactamases

Transmission: part of normal flora in colon, also found in soil and water, occasionally normal flora in respiratory tracts

Tx?: no vaccine

klebsiella pneumoniae - virulence factors

LPS endotoxin = septic shock

capsule = evades phagocytosis

extended spectrum beta lactamases = resistant to almost all abx

klebsiella pneumoniae îs usally an ____ that causes _____

opportunistic pathogen, UTIS and pneumonia (can spread to bloodstream, meninges, and liver; pneumonia with thick, mucoid blood sputum - can progress to abscess and necroses)

Listeria monocytogenes

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Type:

Virulence:

Transmission:

Tx?:

Group:

Type: gram positive bacilli that are motile and live intracellularly

Virulence: beta hemolysis, cold enhancement, internalin, listeriolysin, actin rockets

Transmission: ingestion of contaminated food

Tx?: no vaccine

Listeria monocytogenes - contaminated food ingestion

• unpasteurized milk products, raw veggies, undercooked/deli meats

• distributed worldwide in animals, plants, and soil

• goes from GI tract to colonize vaginal tract

  • can be transmitted via placenta or during delivery