USMLE Step 1 Web Prep — Medically Important Bacteria, Part 3
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SLIDE 1 of 81
Genus: Campylobacter
 Gram negative curved rod with polar flagella
 Microaerophilic, grows well at 42° C on selective media
(Campy medium or Skirrow's agar); oxidase positive
 Reservoir: Intestinal tracts of humans, cattle, sheep,
dogs, cats, poultry
 Transmission: Fecal-oral, primarily from poultry
 Common cause of infectious diarrhea worldwide
 In US, Campylobacter enteritis > (Salmonella +
Shigella)
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SLIDE 2 of 81
Helicobacter pylori
 Gram-negative spiral gastric bacilli with flagella
 Microaerophilic, 37° C growth. (Campy medium or
Skirrow's agar); oxidase positive
 Reservoir: Humans
 Transmission: Fecal-oral, oral-oral
 Urease-positive: ammonium cloud neutralizes stomach
acid allowing survival in stomach acid during transit to
border
 Causes chronic gastritis and duodenal ulcers
 Associated with several forms of stomach cancer
 Breath test: 13C-urea swallowed; ammonia + 13C-CO2
produced
 Treatment: Omeprazole + amoxicillin + clarithromycin +
bismuth
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SLIDE 3 of 81
Helicobacter pylori
 Gram-negative spiral gastric bacilli with flagella
 Microaerophilic, 37° C growth. (Campy medium or
Skirrow's agar); oxidase positive
 Reservoir: Humans
 Transmission: Fecal-oral, oral-oral
 Urease-positive: ammonium cloud neutralizes stomach
acid allowing survival in stomach acid during transit to
border
 Causes chronic gastritis and duodenal ulcers
 Associated with several forms of stomach cancer
 Breath test: 13C-urea swallowed; ammonia + 13C-CO2
produced
 Treatment: Omeprazole + amoxicillin + clarithromycin +
bismuth
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SLIDE 4 of 81
Family: Enterobacteriaceae






Gram-negative rods
Facultative anaerobes
Ferment glucose
Cytochrome C oxidase negative
Reduce nitrates to nitrites
Catalase positive
Pathogenesis (overall for family)
 Endotoxin
 Some also produce exotoxins
 Antigens
O = Cell envelope or O antigen
H = flagellar (motile cells only) antigen
K = capsular polysaccharide antigen
Vi = Salmonella capsular antigen (virulence)
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SLIDE 5 of 81
Family: Enterobacteriaceae
Lab Diagnosis
Grow on 2 media:


Blood
Eosin-methylene blue or MacConkey agar
 Lactose fermenters: CEEK
(colored colonies)
Citrobacter
Escherichia
Enterobacter
Klebsiella
 Non-lactose fermenters: ShYPS
(colorless colonies)
Shigella
nonmotile
Yersinia
non-H2S producers
Proteus
Salmonella
motile
H2S producers
Slow lactose fermenter: Serratia, which produces a
salmon red pigment and is an opportunist.
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SLIDE 6 of 81
Family: Enterobacteriaceae
Lab Diagnosis
Grow on 2 media:


Blood
Eosin-methylene blue or MacConkey agar
 Lactose fermenters: CEEK
(colored colonies)
Citrobacter
Escherichia
Enterobacter
Klebsiella
 Non-lactose fermenters: ShYPS
(colorless colonies)
Shigella
nonmotile
Yersinia
non-H2S producers
Proteus
Salmonella
motile
H2S producers
Slow lactose fermenter: Serratia, which produces a
salmon red pigment and is an opportunist.
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SLIDE 7 of 81
Family: Enterobacteriaceae
Lab Diagnosis
Grow on 2 media:


Blood
Eosin-methylene blue or MacConkey agar
 Lactose fermenters: CEEK
(colored colonies)
Citrobacter
Escherichia
Enterobacter
Klebsiella
 Non-lactose fermenters: ShYPS
(colorless colonies)
Shigella
nonmotile
Yersinia
non-H2S producers
Proteus
Salmonella
motile
H2S producers
Slow lactose fermenter: Serratia, which produces a
salmon red pigment and is an opportunist.
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SLIDE 8 of 81
Family: Enterobacteriaceae
Lab Diagnosis
Grow on 2 media:


Blood
Eosin-methylene blue or MacConkey agar
 Lactose fermenters: CEEK
(colored colonies)
Citrobacter
Escherichia
Enterobacter
Klebsiella
 Non-lactose fermenters: ShYPS
(colorless colonies)
Shigella
nonmotile
Yersinia
non-H2S producers
Proteus
Salmonella
motile
H2S producers
Slow lactose fermenter: Serratia, which produces a
salmon red pigment and is an opportunist.
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SLIDE 9 of 81
Family: Enterobacteriaceae
Lab Diagnosis
Grow on 2 media:


Blood
Eosin-methylene blue or MacConkey agar
 Lactose fermenters: CEEK
(colored colonies)
Citrobacter
Escherichia
Enterobacter
Klebsiella
 Non-lactose fermenters: ShYPS
(colorless colonies)
Shigella
nonmotile
Yersinia
non-H2S producers
Proteus
Salmonella
motile
H2S producers
Slow lactose fermenter: Serratia, which produces a
salmon red pigment and is an opportunist.
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SLIDE 10 of 81
Escherichia coli
 Gram negative rod
 Facultative anaerobic, oxidase negative
 E. coli is lactose-fermenter: colonies with iridescent
green sheen on EMB
 Reservoirs: Human colon; may colonize vagina or
urethra, and contaminated crops where human fecal
fertilizer is used
 Urinary tract infections (UTI)
 Neonatal Septicemia and Meningitis
 Septicemia
 Gastroenteritides/Diarrheas
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SLIDE 11 of 81
Escherichia coli
 Gram negative rod
 Facultative anaerobic, oxidase negative
 E. coli is lactose-fermenter: colonies with iridescent
green sheen on EMB
 Reservoirs: Human colon; may colonize vagina or
urethra, and contaminated crops where human fecal
fertilizer is used
 Urinary tract infections (UTI)
 Neonatal Septicemia and Meningitis
 Septicemia
 Gastroenteritides/Diarrheas
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SLIDE 12 of 81
Escherichia coli
 Gram negative rod
 Facultative anaerobic, oxidase negative
 E. coli is lactose-fermenter: colonies with iridescent
green sheen on EMB
 Reservoirs: Human colon; may colonize vagina or
urethra, and contaminated crops where human fecal
fertilizer is used
 Urinary tract infections (UTI)
 Neonatal Septicemia and Meningitis
 Septicemia
 Gastroenteritides/Diarrheas
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SLIDE 13 of 81
ETEC = Enterotoxigenic E. coli
Major cause of "Traveler’s Diarrhea" and diarrhea in <3 year olds in developing
countries
 Two enterotoxins are produced:


LT: The heat labile toxin stimulates adenylate cyclase by ADP ribosylation of
Gs
o Resulting in increased cAMP causes outflow of chloride ions and water
in small intestine
watery diarrhea
ST: The heat-stabile toxin causes diarrhea by stimulating guanylate cyclase
 Capsule that impedes phagocytosis
 Colonizing factor adhesins (CFAs): bind to small intestine
 Enterotoxin production identified by immunoassay, bioassay or DNA probe assays
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SLIDE 14 of 81
ETEC = Enterotoxigenic E. coli
Major cause of "Traveler’s Diarrhea" and diarrhea in <3
year olds in developing countries
 Two enterotoxins are produced:


LT: The heat labile toxin stimulates adenylate
cyclase by ADP ribosylation of Gs
o Resulting in increased cAMP causes
outflow of chloride ions and water in small
intestine
watery diarrhea
ST: The heat-stabile toxin causes diarrhea by
stimulating guanylate cyclase
 Capsule that impedes phagocytosis
 Colonizing factor adhesins (CFAs): bind to small
intestine
 Enterotoxin production identified by immunoassay,
bioassay or DNA probe assays
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SLIDE 15 of 81
EPEC = Enteropathogenic E. coli
(Second most common cause of diarrhea after
rotavirus)
 Prolonged, watery diarrhea in babies <1 year
in developing countries; often in hospital
nurseries
 Plasmid containing virulences genes called
the E. coli adherence factor (EAF); EPEC
adhere to M cells causing rearrangement of
actin and effacement of the brush border
microvilli
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SLIDE 16 of 81
EIEC = Enteroinvasive E. coli
 Invade large bowel, similar to shigellosis including the
formation of actin "jet trails"
 Often manifests as watery diarrhea (with excess of
leukocytes, however) with fever and abdominal pain.
Only about 10% progress on to dysentery
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SLIDE 17 of 81
EIEC = Enterohemorrhagic E. coli
Also known as Verotoxin producing E. coli (VTEC) or Shiga toxin producing E. coli
(STEC)
 O157:H7 is the most common serotype
 EHEC disease ranges from mild diarrhea without blood to hemorrhagic colitis ±
hemolytic uremic syndrome (HUS)
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SLIDE 18 of 81
Genus: Shigella
 Gram-negative rod
 Enterobacteriaceae
 Nonlactose fermenter
 Nonmotile
 S. dysenteriae (most severe disease), S.
sonnei (most common in U.S.), etc.
 Facultative anaerobes, non-lactose fermenting
: (colorless colonies on EMB or MacConkey)
 Identified by biochemical reactions or by
serology with anti-O antibody in agglutination
test
 Reservoir: Human colon only (no animal
carriers)
 Transmission: Fecal-oral spread, person to
person; as with all fecal-oral spread, the “Four
F’s": fingers, food, feces, flies
 Shiga toxin
 Enterocolitis/Shigellosis: Most severe form
dysentery; few organisms required to start
infection (1-10)
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SLIDE 19 of 81
Genus: Shigella
 Gram-negative rod
 Enterobacteriaceae
 Nonlactose fermenter
 Nonmotile
 S. dysenteriae (most severe disease), S. sonnei (most
common in U.S.), etc.
 Facultative anaerobes, non-lactose fermenting :
(colorless colonies on EMB or MacConkey)
 Identified by biochemical reactions or by serology with
anti-O antibody in agglutination test
 Reservoir: Human colon only (no animal carriers)
 Transmission: Fecal-oral spread, person to person; as
with all fecal-oral spread, the “Four F’s": fingers, food,
feces, flies
 Shiga toxin
 Enterocolitis/Shigellosis: Most severe form dysentery;
few organisms required to start infection (1-10)
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SLIDE 20 of 81
Genus: Shigella
 Gram-negative rod
 Enterobacteriaceae
 Nonlactose fermenter
 Nonmotile
 S. dysenteriae (most severe disease), S. sonnei (most
common in U.S.), etc.
 Facultative anaerobes, non-lactose fermenting :
(colorless colonies on EMB or MacConkey)
 Identified by biochemical reactions or by serology with
anti-O antibody in agglutination test
 Reservoir: Human colon only (no animal carriers)
 Transmission: Fecal-oral spread, person to person; as
with all fecal-oral spread, the “Four F’s": fingers, food,
feces, flies
 Shiga toxin
 Enterocolitis/Shigellosis: Most severe form dysentery;
few organisms required to start infection (1-10)
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SLIDE 21 of 81
Genus: Klebsiella
 Gram-negative rod
 Enterobacteriaceae
 Major polysaccharide capsule
 Mucoid, lactose-fermenting colonies on MacConkey
agar
 Oxidase negative
 Reservoir: Human colon and upper respiratory tract
 Transmission: All commonly from own flora
 Capsule: impedes phagocytosis
 Endotoxin: causes fever, inflammation and shock
(septicemia)
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SLIDE 22 of 81
Genus: Klebsiella
 Gram-negative rod
 Enterobacteriaceae
 Major polysaccharide capsule
 Mucoid, lactose-fermenting colonies on MacConkey
agar
 Oxidase negative
 Reservoir: Human colon and upper respiratory tract
 Transmission: All commonly from own flora
 Capsule: impedes phagocytosis
 Endotoxin: causes fever, inflammation and shock
(septicemia)
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SLIDE 23 of 81
Genus: Klebsiella
 Gram-negative rod
 Enterobacteriaceae
 Major polysaccharide capsule
 Mucoid, lactose-fermenting colonies on MacConkey
agar
 Oxidase negative
 Reservoir: Human colon and upper respiratory tract
 Transmission: All commonly from own flora
 Capsule: impedes phagocytosis
 Endotoxin: causes fever, inflammation and shock
(septicemia)
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SLIDE 24 of 81
Klebsiella pneumoniae
 Community-acquired pneumonia, most often in older
males; most commonly in patients with either chronic
lung disease or alcoholism, or diabetes (but not the most
common cause of pneumonia in alcoholics!)
 Frequent abscesses make it hard to treat; fatality rate
high.
 Catheter-related (nosocomial) from fecal contamination
of catheters
 Septicemia: In immunocompromised patients may
originate from bowel defects or invasion of IV lines
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SLIDE 25 of 81
Klebsiella pneumoniae
 Community-acquired pneumonia, most often in older
males; most commonly in patients with either chronic
lung disease or alcoholism, or diabetes (but not the most
common cause of pneumonia in alcoholics!)
 Frequent abscesses make it hard to treat; fatality rate
high.
 Catheter-related (nosocomial) from fecal contamination
of catheters
 Septicemia: In immunocompromised patients may
originate from bowel defects or invasion of IV lines
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SLIDE 26 of 81
Klebsiella pneumoniae
 Community-acquired pneumonia, most often
in older males; most commonly in patients with
either chronic lung disease or alcoholism, or
diabetes (but not the most common cause of
pneumonia in alcoholics!)
 Frequent abscesses make it hard to treat;
fatality rate high.
 Catheter-related (nosocomial) from fecal
contamination of catheters
 Septicemia: In immunocompromised patients
may originate from bowel defects or invasion of
IV lines
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SLIDE 27 of 81
Genus: Salmonella
 Gram-negative rod (Enterobacteriaceae)
 Non-lactose fermenter
 Motile
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SLIDE 29 of 81
Salmonella typhi
 Gram-negative rods, highly motile with the Vi capsule
 Facultative anaerobe, non-lactose fermenting
 Produces H2S
 Reservoir: Humans only; NO ANIMAL RESERVOIRS
 Transmission: Fecal-oral route from human carriers
(gall bladder)
 Typhoid Fever (Enteric Fever), S. typhi
 3 vaccines: attenuated oral vaccine of S. typhi strain 21
(Ty21a), parenteral heat killed S. typhi, and parenteral Vi
polysaccharide capsular vaccine
130900 >>> 0:21:44.2
SLIDE 30 of 81
Salmonella typhi
 Gram-negative rods, highly motile with the Vi capsule
 Facultative anaerobe, non-lactose fermenting
 Produces H2S
 Reservoir: Humans only; NO ANIMAL RESERVOIRS
 Transmission: Fecal-oral route from human carriers
(gall bladder)
 Typhoid Fever (Enteric Fever), S. typhi
 3 vaccines: attenuated oral vaccine of S. typhi strain 21
(Ty21a), parenteral heat killed S. typhi, and parenteral Vi
polysaccharide capsular vaccine
130905 >>> 0:21:57.2
SLIDE 31 of 81
Salmonella typhi
 Gram-negative rods, highly motile with the Vi capsule
 Facultative anaerobe, non-lactose fermenting
 Produces H2S
 Reservoir: Humans only; NO ANIMAL RESERVOIRS
 Transmission: Fecal-oral route from human carriers
(gall bladder)
 Typhoid Fever (Enteric Fever), S. typhi
 3 vaccines: attenuated oral vaccine of S. typhi strain 21
(Ty21a), parenteral heat killed S. typhi, and parenteral Vi
polysaccharide capsular vaccine
130891 >>> 0:22:05.2
SLIDE 28 of 81
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SLIDE 32 of 81
Salmonella typhi
 Gram-negative rods, highly motile with the Vi capsule
 Facultative anaerobe, non-lactose fermenting
 Produces H2S
 Reservoir: Humans only; NO ANIMAL RESERVOIRS
 Transmission: Fecal-oral route from human carriers
(gall bladder)
 Typhoid Fever (Enteric Fever), S. typhi
 3 vaccines: attenuated oral vaccine of S. typhi strain 21
(Ty21a), parenteral heat killed S. typhi, and parenteral Vi
polysaccharide capsular vaccine
130915 >>> 0:24:50.2
SLIDE 33 of 81
Salmonella typhi
 Gram-negative rods, highly motile with the Vi
capsule
 Facultative anaerobe, non-lactose fermenting
 Produces H2S
 Reservoir: Humans only; NO ANIMAL
RESERVOIRS
 Transmission: Fecal-oral route from human
carriers (gall bladder)
 Typhoid Fever (Enteric Fever), S. typhi
 3 vaccines: attenuated oral vaccine of S. typhi
strain 21 (Ty21a), parenteral heat killed S. typhi,
and parenteral Vi polysaccharide capsular
vaccine
130920 >>> 0:25:06.2
SLIDE 34 of 81
Salmonella typhi
 Gram-negative rods, highly motile with the Vi capsule
 Facultative anaerobe, non-lactose fermenting
 Produces H2S
 Reservoir: Humans only; NO ANIMAL RESERVOIRS
 Transmission: Fecal-oral route from human carriers
(gall bladder)
 Typhoid Fever (Enteric Fever), S. typhi
 3 vaccines: attenuated oral vaccine of S. typhi strain 21
(Ty21a), parenteral heat killed S. typhi, and parenteral Vi
polysaccharide capsular vaccine
130921 >>> 0:25:34.2
SLIDE 35 of 81
Non-typhoidal Salmonellae: S. enteritidis, S. typhimurium, and other
species
 Facultative gram-negative rods, non-lactose-fermenting on EMB, MacConkey
medium
 Produces H2S, motile (unlike Shigella)
 Reservoir: Enteric tracts of human and domestic animals, e.g., chickens and turtles
 Transmission: Largely through chicken products (raw chicken and eggs) in the
kitchen
 Enterocolitis/Gastroenteritis, Septicemia
130925 >>> 0:25:52.2
SLIDE 36 of 81
Non-typhoidal Salmonellae: S.
enteritidis, S. typhimurium, and other
species
 Facultative gram-negative rods, non-lactosefermenting on EMB, MacConkey medium
 Produces H2S, motile (unlike Shigella)
 Reservoir: Enteric tracts of human and
domestic animals, e.g., chickens and turtles
 Transmission: Largely through chicken
products (raw chicken and eggs) in the kitchen
 Enterocolitis/Gastroenteritis, Septicemia
130930 >>> 0:25:55.2
SLIDE 37 of 81
Non-typhoidal Salmonellae: S. enteritidis, S.
typhimurium, and other species
 Facultative gram-negative rods, non-lactose-fermenting
on EMB, MacConkey medium
 Produces H2S, motile (unlike Shigella)
 Reservoir: Enteric tracts of human and domestic
animals, e.g., chickens and turtles
 Transmission: Largely through chicken products (raw
chicken and eggs) in the kitchen
 Enterocolitis/Gastroenteritis, Septicemia
130935 >>> 0:26:00.2
SLIDE 38 of 81
Non-typhoidal Salmonellae: S. enteritidis, S.
typhimurium, and other species
 Facultative gram-negative rods, non-lactose-fermenting
on EMB, MacConkey medium
 Produces H2S, motile (unlike Shigella)
 Reservoir: Enteric tracts of human and domestic
animals, e.g., chickens and turtles
 Transmission: Largely through chicken products (raw
chicken and eggs) in the kitchen
 Enterocolitis/Gastroenteritis, Septicemia
130936 >>> 0:27:15.2
SLIDE 39 of 81
Yersinia pestis
 Small gram-negative rods with bipolar staining
 Facultative intracellular parasite
 Coagulase +
 Clinical specimens and cultures are hazardous
 Reservoir: U.S Desert southwest, rodents, e.g., prairie dogs, chipmunks, squirrels,
field mice, and voles
 Transmission: Wild rodents flea bite
sylvatic plague
 Human-to-human transmission by respiratory droplets
 Causes bubonic plague and pneumonic plague
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SLIDE 40 of 81
Genus: Proteus (Proteus mirabilis, Proteus vulgaris)
 Gram-negative rod
 Enterobacteriaceae
 Peritrichous flagella
 Non lactose-fermenting
 Urease positive
 Highly motile. “Swarming” motility on surface of blood agar
 Facultative anaerobe (Enterobacteriaceae) oxidase negative
 Reservoir: Human colon and environment (water and soil)
 Disease: Urinary tract infection and septicemia
 Antigens of OX strains of Proteus vulgaris cross react with antibodies from most
Rickettsial diseases (Weil-Felix test)
130940 >>> 0:28:44.2
SLIDE 41 of 81
Genus: Proteus (Proteus mirabilis, Proteus
vulgaris)
 Gram-negative rod
 Enterobacteriaceae
 Peritrichous flagella
 Non lactose-fermenting
 Urease positive
 Highly motile. “Swarming” motility on surface of blood
agar
 Facultative anaerobe (Enterobacteriaceae) oxidase
negative
 Reservoir: Human colon and environment (water and
soil)
 Disease: Urinary tract infection and septicemia
 Antigens of OX strains of Proteus vulgaris cross react
with antibodies from most Rickettsial diseases (Weil-Felix
test)
130945 >>> 0:29:00.2
SLIDE 42 of 81
Genus: Proteus (Proteus mirabilis, Proteus
vulgaris)
 Gram-negative rod
 Enterobacteriaceae
 Peritrichous flagella
 Non lactose-fermenting
 Urease positive
 Highly motile. “Swarming” motility on surface of blood
agar
 Facultative anaerobe (Enterobacteriaceae) oxidase
negative
 Reservoir: Human colon and environment (water and
soil)
 Disease: Urinary tract infection and septicemia
 Antigens of OX strains of Proteus vulgaris cross react
with antibodies from most Rickettsial diseases (Weil-Felix
test)
130950 >>> 0:29:29.2
SLIDE 43 of 81
Genus: Proteus (Proteus mirabilis, Proteus
vulgaris)
 Gram-negative rod
 Enterobacteriaceae
 Peritrichous flagella
 Non lactose-fermenting
 Urease positive
 Highly motile. “Swarming” motility on surface of blood
agar
 Facultative anaerobe (Enterobacteriaceae) oxidase
negative
 Reservoir: Human colon and environment (water and
soil)
 Disease: Urinary tract infection and septicemia
 Antigens of OX strains of Proteus vulgaris cross react
with antibodies from most Rickettsial diseases (Weil-Felix
test)
130955 >>> 0:30:15.2
SLIDE 44 of 81
Genus: Vibrio (Vibrio cholerae)
 Gram-negative curved rod with polar flagella
 Oxidase positive (Vibrionaceae)
 Two different biotypes
 Growth on alkaline but not acidic media (TCBS =
Thiosulfate Citrate Bile salt Sucrose medium)
 Reservoir: Human colon; no vertebrate animal carriers
 Transmission: Fecal-oral spread
 Cholera enterotoxin
 Rice water stools, tremendous fluid loss; hypovolemic
shock if not treated
130960 >>> 0:30:28.2
SLIDE 45 of 81
Genus: Vibrio (Vibrio cholerae)
 Gram-negative curved rod with polar flagella
 Oxidase positive (Vibrionaceae)
 Two different biotypes
 Growth on alkaline but not acidic media (TCBS =
Thiosulfate Citrate Bile salt Sucrose medium)
 Reservoir: Human colon; no vertebrate animal
carriers
 Transmission: Fecal-oral spread
 Cholera enterotoxin
 Rice water stools, tremendous fluid loss;
hypovolemic shock if not treated
130965 >>> 0:32:08.2
SLIDE 46 of 81
Genus: Vibrio (Vibrio cholerae)
 Gram-negative curved rod with polar flagella
 Oxidase positive (Vibrionaceae)
 Two different biotypes
 Growth on alkaline but not acidic media (TCBS =
Thiosulfate Citrate Bile salt Sucrose medium)
 Reservoir: Human colon; no vertebrate animal carriers
 Transmission: Fecal-oral spread
 Cholera enterotoxin
 Rice water stools, tremendous fluid loss; hypovolemic
shock if not treated
130966 >>> 0:33:03.2
SLIDE 47 of 81
Vibrio parahaemolyticus




Food poisoning associated with undercooked or raw seafood
Marine
5-94 hours incubation (mean 24 hours)
Self-limiting watery diarrhea with cramping, abdominal pain
130970 >>> 0:33:51.2
SLIDE 48 of 81
Vibrio parahaemolyticus
 Food poisoning associated with undercooked or raw
seafood
 Marine
 5-94 hours incubation (mean 24 hours)
 Self-limiting watery diarrhea with cramping, abdominal
pain
130971 >>> 0:34:10.2
SLIDE 49 of 81
Genus: Pasteurella (Pasteurella multocida)




Small gram-negative rods
Facultative anaerobic rods
Reservoir: Mouths of many animals, especially cats and dogs
Transmission: Animal bites; particularly from cat bites
130975 >>> 0:34:48.2
SLIDE 50 of 81
Genus: Haemophilus (Haemophilus influenzae)
 Very short (clinical specimens); pleomorphic from
culture
 Fastidious: requires factors X (hemin) and V (NAD) for
growth on nutrient or blood agar; grows near S. aureus
on BA = "Satellite" phenomenon; chocolate agar provides
both
 Polysaccharide capsule (type b capsule is polyribitol
phosphate) most important virulence factor
 Meningitis
 Otitis Media: Usually non-typeable strains
 Epiglottitis: Rare in vaccinated kids
 Vaccination effective to prevent type b disease: 2, 4, 6
months; booster 15 months; 95% effective
130980 >>> 0:35:02.2
SLIDE 51 of 81
Genus: Haemophilus (Haemophilus influenzae)
 Very short (clinical specimens); pleomorphic from
culture
 Fastidious: requires factors X (hemin) and V (NAD) for
growth on nutrient or blood agar; grows near S. aureus
on BA = "Satellite" phenomenon; chocolate agar provides
both
 Polysaccharide capsule (type b capsule is polyribitol
phosphate) most important virulence factor
 Meningitis
 Otitis Media: Usually non-typeable strains
 Epiglottitis: Rare in vaccinated kids
 Vaccination effective to prevent type b disease: 2, 4, 6
months; booster 15 months; 95% effective
130985 >>> 0:36:08.2
SLIDE 52 of 81
Genus: Haemophilus (Haemophilus influenzae)
 Very short (clinical specimens); pleomorphic from
culture
 Fastidious: requires factors X (hemin) and V (NAD) for
growth on nutrient or blood agar; grows near S. aureus
on BA = "Satellite" phenomenon; chocolate agar provides
both
 Polysaccharide capsule (type b capsule is polyribitol
phosphate) most important virulence factor
 Meningitis
 Otitis Media: Usually non-typeable strains
 Epiglottitis: Rare in vaccinated kids
 Vaccination effective to prevent type b disease: 2, 4, 6
months; booster 15 months; 95% effective
130990 >>> 0:36:30.2
SLIDE 53 of 81
Genus: Haemophilus (Haemophilus influenzae)
 Very short (clinical specimens); pleomorphic from
culture
 Fastidious: requires factors X (hemin) and V (NAD) for
growth on nutrient or blood agar; grows near S. aureus
on BA = "Satellite" phenomenon; chocolate agar provides
both
 Polysaccharide capsule (type b capsule is polyribitol
phosphate) most important virulence factor
 Meningitis
 Otitis Media: Usually non-typeable strains
 Epiglottitis: Rare in vaccinated kids
 Vaccination effective to prevent type b disease: 2, 4, 6
months; booster 15 months; 95% effective
130995 >>> 0:37:02.2
SLIDE 54 of 81
Genus: Haemophilus (Haemophilus
influenzae)
 Very short (clinical specimens); pleomorphic from
culture
 Fastidious: requires factors X (hemin) and V (NAD)
for growth on nutrient or blood agar; grows near S.
aureus on BA = "Satellite" phenomenon; chocolate
agar provides both
 Polysaccharide capsule (type b capsule is polyribitol
phosphate) most important virulence factor
 Meningitis
 Otitis Media: Usually non-typeable strains
 Epiglottitis: Rare in vaccinated kids
 Vaccination effective to prevent type b disease: 2, 4,
6 months; booster 15 months; 95% effective
131000 >>> 0:37:16.2
SLIDE 55 of 81
Genus: Haemophilus (Haemophilus
influenzae)
 Very short (clinical specimens); pleomorphic from
culture
 Fastidious: requires factors X (hemin) and V (NAD)
for growth on nutrient or blood agar; grows near S.
aureus on BA = "Satellite" phenomenon; chocolate
agar provides both
 Polysaccharide capsule (type b capsule is polyribitol
phosphate) most important virulence factor
 Meningitis
 Otitis Media: Usually non-typeable strains
 Epiglottitis: Rare in vaccinated kids
 Vaccination effective to prevent type b disease: 2, 4,
6 months; booster 15 months; 95% effective
131005 >>> 0:38:46.2
SLIDE 56 of 81
Haemophilus ducreyi




Sexually transmitted disease
Chancroid (genital ulcers): soft, painful chancre
Slow to heal without treatment
Open lesions increase transmission of HIV
131010 >>> 0:39:08.2
SLIDE 57 of 81
Haemophilus ducreyi




Sexually transmitted disease
Chancroid (genital ulcers): soft, painful chancre
Slow to heal without treatment
Open lesions increase transmission of HIV
131015 >>> 0:39:42.2
SLIDE 58 of 81
Haemophilus ducreyi




Sexually transmitted disease
Chancroid (genital ulcers): soft, painful chancre
Slow to heal without treatment
Open lesions increase transmission of HIV
131016 >>> 0:39:55.2
SLIDE 59 of 81
Genus: Bacteroides (Bacteroides fragilis)
 Gram-negative rod
 Anaerobic
 Modified LPS with reduced activity
 Anaerobes are identified by biochemical tests and gas chromatography
 Reservoir: Human colon; the predominant anaerobe
 Transmission: Endogenous from bowel defects (e.g., from cytotoxic drug use,
cancer), surgery, or trauma
 Septicemia, peritonitis (often mixed infections), and abdominal abscess
 Treatment: Metronidazole, clindamycin, or cefoxitin. Abscesses should be
surgically drained
131020 >>> 0:40:49.2
SLIDE 60 of 81
Genus: Bacteroides (Bacteroides fragilis)
 Gram-negative rod
 Anaerobic
 Modified LPS with reduced activity
 Anaerobes are identified by biochemical tests and gas
chromatography
 Reservoir: Human colon; the predominant anaerobe
 Transmission: Endogenous from bowel defects (e.g.,
from cytotoxic drug use, cancer), surgery, or trauma
 Septicemia, peritonitis (often mixed infections), and
abdominal abscess
 Treatment: Metronidazole, clindamycin, or cefoxitin.
Abscesses should be surgically drained
131025 >>> 0:41:14.2
SLIDE 61 of 81
Genus: Bacteroides (Bacteroides fragilis)
 Gram-negative rod
 Anaerobic
 Modified LPS with reduced activity
 Anaerobes are identified by biochemical tests and gas
chromatography
 Reservoir: Human colon; the predominant anaerobe
 Transmission: Endogenous from bowel defects (e.g.,
from cytotoxic drug use, cancer), surgery, or trauma
 Septicemia, peritonitis (often mixed infections), and
abdominal abscess
 Treatment: Metronidazole, clindamycin, or cefoxitin.
Abscesses should be surgically drained
131030 >>> 0:41:41.2
SLIDE 62 of 81
Bacteroides melaninogenicus = Prevotella
melaninogenica




Melanin-producing (black) Bacteroides
Normal gingival flora
Anaerobe
Oral abscesses
131035 >>> 0:43:01.2
SLIDE 63 of 81
Genus: Treponema (Treponema
pallidum)
 Thin spirochete, not reliably seen on gram
stain
 Basically a gram-negative cell envelope
 Axial filaments = endoflagella = periplasmic
flagella
 Cannot culture in clinical lab; serodiagnosis
 Is an obligate pathogen (but not intracellular)
 Reservoir/Transmission: Human genital tract;
transmitted sexually or across the placenta
131040 >>> 0:44:15.2
SLIDE 64 of 81
Treponema pallidum
 Primary syphilis:




Nontender chancre(s) at site of inoculation
Margins generally "clean," distinctly indurated
edge
Contagious (but you still cannot culture!)
Heals spontaneously in 3-6 weeks
131045 >>> 0:44:33.2
SLIDE 65 of 81
Treponema pallidum
 Primary syphilis:




Nontender chancre(s) at site of inoculation
Margins generally "clean," distinctly indurated
edge
Contagious (but you still cannot culture!)
Heals spontaneously in 3-6 weeks
131050 >>> 0:44:45.2
SLIDE 66 of 81
Treponema pallidum
 Primary syphilis:




Nontender chancre(s) at site of inoculation
Margins generally "clean," distinctly indurated
edge
Contagious (but you still cannot culture!)
Heals spontaneously in 3-6 weeks
131055 >>> 0:44:49.2
SLIDE 67 of 81
Treponema pallidum
 Primary syphilis:




Nontender chancre(s) at site of inoculation
Margins generally "clean," distinctly indurated
edge
Contagious (but you still cannot culture!)
Heals spontaneously in 3-6 weeks
131060 >>> 0:44:52.2
SLIDE 68 of 81
Treponema pallidum
 Primary syphilis:




Nontender chancre(s) at site of inoculation
Margins generally "clean," distinctly indurated
edge
Contagious (but you still cannot culture!)
Heals spontaneously in 3-6 weeks
131065 >>> 0:44:56.2
SLIDE 69 of 81
Treponema pallidum
 Primary syphilis:




Nontender chancre(s) at site of inoculation
Margins generally "clean," distinctly indurated
edge
Contagious (but you still cannot culture!)
Heals spontaneously in 3-6 weeks
131070 >>> 0:45:31.2
SLIDE 70 of 81
Treponema pallidum
 Secondary syphilis:





1 to 3 months later. (T. pallidum has spread early
via bloodstream)
Maculopapular (often copper colored) rash on skin
including palms and soles ± patchy alopecia
Flat wart-like perianal condylomata lata and
mucous membranes lesions, both highly infectious
May ‘heal’ spontaneously, regress (several times)
and finally heal
Serology is almost always strongly reactive
131075 >>> 0:45:41.2
SLIDE 71 of 81
Treponema pallidum
 Secondary syphilis:



1 to 3 months later. (T. pallidum has spread early
via bloodstream)
Maculopapular (often copper colored) rash on skin
including palms and soles ± patchy alopecia
Flat wart-like perianal condylomata lata and
mucous membranes lesions, both highly infectious


May ‘heal’ spontaneously, regress (several times)
and finally heal
Serology is almost always strongly reactive
131080 >>> 0:45:52.2
SLIDE 72 of 81
Treponema pallidum
 Secondary syphilis:





1 to 3 months later. (T. pallidum has spread early
via bloodstream)
Maculopapular (often copper colored) rash on skin
including palms and soles ± patchy alopecia
Flat wart-like perianal condylomata lata and
mucous membranes lesions, both highly infectious
May ‘heal’ spontaneously, regress (several times)
and finally heal
Serology is almost always strongly reactive
131085 >>> 0:46:10.2
SLIDE 73 of 81
Treponema pallidum
 Tertiary syphilis:
 May be years later in about one-third of the untreated
patients
 Tertiary lesions consist of gummas, aortitis, or central
nervous system inflammation. VDRL may be negative
131090 >>> 0:47:02.2
SLIDE 74 of 81
Treponema pallidum
 Congenital syphilis:
 Sx: stillbirths, multiple fetal abnormalities (keratitis, 8th
nerve deafness, notched teeth), or sometimes
asymptomatic (or snuffles) at birth until two
131095 >>> 0:47:36.2
SLIDE 75 of 81
Treponema pallidum
 Congenital syphilis:
 Sx: stillbirths, multiple fetal abnormalities (keratitis, 8th
nerve deafness, notched teeth), or sometimes
asymptomatic (or snuffles) at birth until two
131100 >>> 0:48:09.2
SLIDE 76 of 81
Treponema pallidum
Laboratory Diagnosis
Visualize organisms by immunofluorescence or darkfield microscopy
Serology important: Two types of antibody:
1. Nontreponemal antibody (= reagin):
o
o
Binds to cardiolipin
 an antigen found in mammalian
mitochondrial membranes and in
treponemes (but probably are
from the host since treponemes
don't make).
 cheap source of antigen is cow
heart, which is used in screening
tests (VDRL, RPR, ART)
Screening tests: Nontreponemal
antibody tests:
 Venereal Disease Research Lab
(VDRL)
 Rapid plasma reagin (RPR)
 Automated Reagin Test (ART)
 Any one may be used for
screening (inexpensive)
 Very sensitive in primary (except
early) and secondary; titer may
decline in tertiary
2. Treponemal antibody:
o
o
Earliest antibody, binds to spirochetes
Specific tests for Treponema (more
expensive):
 Fluorescent Treponemal
Antibody-Absorption (FTA-ABS;
most widely used test)

Treponemal pallidum
Microhemagglutination
These tests are more specific and positive earlier;
usually remains positive for life. But positive in patients
with other treponeme disease (bejel) and may be
positive in Lyme disease
Treatment: Benzathine penicillin (long-acting form) for
primary and secondary syphilis
131105 >>> 0:48:40.2
SLIDE 77 of 81
Treponema pallidum
Laboratory Diagnosis
Visualize organisms by immunofluorescence or dark-field
microscopy
Serology important: Two types of antibody:
1. Nontreponemal antibody (= reagin):
o
o
Binds to cardiolipin
 an antigen found in mammalian
mitochondrial membranes and in
treponemes (but probably are from
the host since treponemes don't
make).
 cheap source of antigen is cow
heart, which is used in screening
tests (VDRL, RPR, ART)
Screening tests: Nontreponemal antibody
tests:
 Venereal Disease Research Lab
(VDRL)
 Rapid plasma reagin (RPR)
 Automated Reagin Test (ART)
 Any one may be used for screening
(inexpensive)
 Very sensitive in primary (except
early) and secondary; titer may
decline in tertiary
2. Treponemal antibody:
o
o
Earliest antibody, binds to spirochetes
Specific tests for Treponema (more
expensive):
 Fluorescent Treponemal AntibodyAbsorption (FTA-ABS; most widely
used test)
 Treponemal pallidum
Microhemagglutination
These tests are more specific and positive earlier; usually
remains positive for life. But positive in patients with other
treponeme disease (bejel) and may be positive in Lyme
disease
Treatment: Benzathine penicillin (long-acting form) for
primary and secondary syphilis
131110 >>> 0:49:58.2
SLIDE 78 of 81
Treponema pallidum
Laboratory Diagnosis
Visualize organisms by immunofluorescence or dark-field
microscopy
Serology important: Two types of antibody:
1. Nontreponemal antibody (= reagin):
o
o
Binds to cardiolipin
 an antigen found in mammalian
mitochondrial membranes and in
treponemes (but probably are from
the host since treponemes don't
make).
 cheap source of antigen is cow
heart, which is used in screening
tests (VDRL, RPR, ART)
Screening tests: Nontreponemal antibody
tests:
 Venereal Disease Research Lab
(VDRL)
 Rapid plasma reagin (RPR)
 Automated Reagin Test (ART)
 Any one may be used for screening
(inexpensive)
 Very sensitive in primary (except
early) and secondary; titer may
decline in tertiary
2. Treponemal antibody:
o
o
Earliest antibody, binds to spirochetes
Specific tests for Treponema (more
expensive):
 Fluorescent Treponemal AntibodyAbsorption (FTA-ABS; most widely
used test)
 Treponemal pallidum
Microhemagglutination
These tests are more specific and positive earlier; usually
remains positive for life. But positive in patients with other
treponeme disease (bejel) and may be positive in Lyme
disease
Treatment: Benzathine penicillin (long-acting form) for
primary and secondary syphilis
131115 >>> 0:51:02.2
SLIDE 79 of 81
Genus: Borrelia (Borrelia burgdorferi)
 Spirochete, not seen well on gram-stained smear; can
be cultured in vitro
 Gram-negative
 Microaerophilic
 Two reservoirs: white-footed mice (nymphs) and whitetailed deer (adult ticks)
 Transmission: By Ixodes (deer) ticks
 Lyme Disease: B. burgdorferi invades skin and spreads
via the bloodstream to involve primarily the heart, joints,
and central nervous system
 Arthritis is caused by immune complexes
131120 >>> 0:52:00.2
SLIDE 80 of 81
Borrelia burgdorferi
Lyme Disease
 Initial symptoms:
 Erythema (chronicum) migrans: spreading
annular skin lesion with an erythematous leading
edge and central clearing, "bull's eye" seen in
85% of cases.
 Malaise, headache, severe fatigue, fever,
chills
 Musculoskeletal pain, lymphadenopathy
 One to several weeks dissemination:
 Neurological: severe headache, meningitis,
cranial nerve palsies (Bell's palsy)
 Cardiac: arrhythmias, myocarditis, pericarditis
 Late and lasting for months or years:
arthralgias, arthritis (Sx in 80% within few weeks
to 2 years)
131123 >>> 0:53:07.2
SLIDE 81 of 81
Genus: Leptospira (Leptospira interrogans)
 Spirochetes with tight terminal hooks
 Reservoir: Wild and domestic animals
 Transmission: Via animal urine in water
 Leptospirosis disease triad: renal failure, meningitis, myocarditis