M3.1 Flashcards
1
Q
NEISSERIA MENINGITIDIS
Gram? Shape?
Capsule?
Oxidase?
Ferments?
A
• gram-negative “kidney-bean” diplococci
• large polysaccharide capsule
• oxidase-positive colonies on chocolate agar
• ferments maltose and glucose
2
Q
NEISSERIA MENINGITIDIS
HABITAT AND TRANSMISSION
A
• habitat is the URT
• transmission via respiratory droplets
• humans are the only natural hosts
• complement deficiencies in the late-acting complement
components (C5b–C9) predispose to illness
• high carriage rate in close quarters
o military recruits, dormitories, camps, travel (e.g., epidemic related to traveling to Saudi Arabia for the Hajj pilgrimage)
3
Q
NEISSERIA MENINGITIDIS
PATHOGENESIS
A
• antiphagocytic polysaccharide capsule
• endotoxin (LPS)- highest level of endotoxin measured in sepsis
• Porin proteins- controls nutrient diffusion
• Opa- attachment
• Pili- binding to nasopharyngeal epithelial cells
4
Q
NEISSERIA MENINGITIDIS
Portalof entry
A
Nasopharynx
5
Q
highest level of endotoxin measured in sepsis
A
endotoxin (LPS)
6
Q
NEISSERIA MENINGITIDIS
SPECTRUM OF DISEASE
A
Meningitis
Meningococcemia
Waterhouse-Friderichsen Syndrome
7
Q
most common cause of meningitis among aged 2-18 yrs
Manifestation?
A
NEISSERIA MENINGITIDIS
fever, headache, stiff neck, and an increased level of PMNs in spinal fluid
8
Q
o dissemination of meningococci into the bloodstream
o multiorgan disease, consumptive coagulopathy, petechial or
purpuric rash (purpura fulminans)
A
Meningococcemia
9
Q
most severe form of meningococcemia
A
Waterhouse-Friderichsen Syndrome
o high fever, shock, widespread purpura, disseminated
intravascular coagulation, thrombocytopenia, and adrenal
insufficiency
§ bilateral hemorrhagic destruction of the adrenal glands
10
Q
NEISSERIA MENINGITIDIS
TREATMENT
A
penicillin G
11
Q
NEISSERIA MENINGITIDIS
vaccine contains capsular polysaccharide of strains
A
A, C, Y, and
W-135
12
Q
Post-exposure prophylaxis to close contacts
A
o Rifampicin
o Ciprofloxacin
o Ceftriaxone
13
Q
Which of the following virulence factors allows adherence of bacteria
to the mucous membranes of the respiratory, genitourinary and
gastrointestinal tracts?
A. Panton-Valentine Leukocidin
B. Hyaluronidase
C. Coagulase
D. IgA protease
A
D. IgA protease
14
Q
Which capsular type of Neisseria meningitidis lacks immunogenicity
even with protein conjugation, hence, not included in the vaccine?
A. A
B. B
C. C
D. Y
E. W-135
A
B. B
15
Q
NEISSERIA GONORRHOEAE
Gram? Shape?
Capsule?
Oxidase?
Ferments?
A
• gram-negative “kidney-bean” diplococci
• insignificant capsule
• oxidase-positive colonies on Thayer-Martin medium
• ferment glucose only
16
Q
The modified Thayer-Martin medium contains which antibiotics?
A. Voriconazole, cefuroxime, netilmicin
B. Vancomycin, colistin, nystatin
C. Vancomycin, ciprofloxacin, neosporin
D. Voriconazole, cotrimoxazole, nystatin
A
B. Vancomycin, colistin, nystatin
17
Q
NEISSERIA GONORRHOEAE
HABITAT AND TRANSMISSION
A
• habitat is the human genital tract
• transmission by sexual contact or during passage through birth canal
• complement deficiencies in the late-acting complement
components (C5b–C9) predispose to illness
o cannot form membrane-attack complexes
18
Q
NEISSERIA GONORRHOEAE
PATHOGENESIS
A
IgA protease – destroys mucosal antibodies that would inhibit
epithelial colonization
• Lipooligosaccharide (LOS) – devoid of long O-antigen side
chains, toxicity of gonococcal infections largely attributable to LOS
• Opa – adhesion of gonococci within colonies and attachment to
host cell receptors, expression results in opaque colonies
• Pili – enhances attachment to host cells, made up of pilin proteins
that are antigenically distinct (accounts for antigenic variation)
• usual co-infection with Chlamydia trachomatis
19
Q
most common cause of urethritis
most common cause of PID
most common cause in sexually active adults
A
NEISSERIA GONORRHOEAE
20
Q
NEISSERIA GONORRHOEAE
SPECTRUM OF DISEASE: LOCALIZED
A
Ophthalmia Neonatorum
o purulent conjunctivitis in newborns
• Gonococcal Urethritis
o urethritis and epididymitis in men
• Pelvic Inflammatory Disease
complications:
§ sterility
§ ectopic pregnancy
§ chronic pelvic pain
§ dyspareunia
§ Fitz-Hugh-Curtis syndrome (perihepatitis): violin-string
adhesions
21
Q
NEISSERIA GONORRHOEAE
SPECTRUM OF DISEASE: DISSEMINATED
A
Septic Arthritis
o arthritis, tenosynovitis, or pustules in the skin
22
Q
gold standard for the
diagnosis of gonorrheal infections
A
Nucleic acid amplification test (NAAT)
23
Q
NEISSERIA GONORRHOEAE
Culture Appearance
A
• “Opaque Colonies” = specimen came from symptomatic male
(urethritis) OR midcycle uterine culture
• “Transparent Colonies” = specimen came from asymptomatic male
OR menstruating women OR invasive / disseminated gonorrhea
24
Q
Presumptive Diagnosis of Gonorrhea
If Male, (+) microscopic from Urethral specimen:
A
NO OTHER TESTS
NEEDED
25
Presumptive Diagnosis of Gonorrhea
If Female, (+) microscopic Endocervix specimen:
Do NAAT or
CULTURE
26
NEISSERIA GONORRHOEAE
TREATMENT
• Single dose of ceftriaxone 500 mg IM (intramuscular injection)
• For completeness, also consider the treatment for possible coinfection
with chlamydia. The CDC recommends treating with doxycycline 100
mg orally twice a day for 7 days, unless contraindicated (e.g., in pregnancy, where azithromycin is preferred)
27
A 26-year-old male presents to his primary care physician with
complaints of burning with urination, penile discharge, and
intermittent fevers. A urethral smear shows gram negative diplococci
within white blood cells. The organism grows well when cultured on
Thayer-Martin agar. The patient is prescribed a course of ceftriaxone,
and the infection resolves without further complication. One year
later, the patient returns with the same infection. Which of the
following best explains this lack of lasting immunity?
A. Antigenic variation
B. Polysaccharide capsule
C. Bruton's agammaglobulinemia
D. Lack of necessary vaccination
E. HIV infection
A. Antigenic variation
28
A 22-year-old sexually active man complains of purulent urethral
discharge and dysuria after having unprotected sex at a college
party. Which of the following is the most sensitive test to diagnose
the most likely causative agent?
A. Gram stain of the urethral discharge
B. Culture
C. Serology
D. Nucleic acid amplification test
D. Nucleic acid amplification test
29
2 weeks later, the patient comes back to the clinic complaining of
persistence of urethral discharge. What is the best test to order to
reevaluate his case?
A. Gram stain of the urethral discharge
B. Culture
C. Serology
D. Nucleic acid amplification test
B. Culture
30
N. gonorrhea is the most common cause of _____
bacterial conjunctivitis in adults
Hyperacute
31
In which of the following exudate specimen can a positive smear for
Neisseria gonorrhoeae be a basis for presumptive diagnosis of
gonorrhea and start treatment without additional laboratory test?
a. Throat
b. Endocervical
c. Urethral
d. Rectal
c. Urethral
32
NEISSERIA MENINGITIDIS
Most common form of infection:
Asymptomatic carriage
33
Waterhouse Friderichsen Syndrome
Also known as
Manifests as:
○ hemorrhagic adrenalitis
○ Fulminant meningoccocemia
○ Adrenal gland failure due to bleeding into the adrenal glands caused by severe bacterial infection, most commonly due to
■ Hyponatremia
■ Hyperkalemia
■ Hypoglycemia
34
Which of the following is the most widely used prophylactic drug for
meningococcemia in the local setting?
a. Rifampicin
b. Ceftriaxone
c. Ciprofloxacin
d. Penicillin G
c. Ciprofloxacin
35
gram negative rods
enriched chocolate agar,
Polyribitol phosphate
capsule
Haemophilus
influenzae type b
36
gram negative rods
Bordet-Gengou agar,
whooping cough
Bordetella
pertussis
37
gram negative rods
poorly gram staining, silver
stain, charcoal yeast agar,
air-conditioning
Legionella
pneumophila
38
HAEMOPHILUS INFLUENZAE
Gram? Shape?
Fastidious?
Requires?
Hemolysis?
Quellung test?
small gram-negative (coccobacillary) rods
fastidious organism
X HEMIN
V NAD
Hemolysis -
Satellite phenomenon
Quellung test +
39
HAEMOPHILUS INFLUENZAE
HABITAT AND TRANSMISSION
• habitat is upper respiratory tract
• transmission via respiratory droplets
40
HAEMOPHILUS INFLUENZAE
PATHOGENESIS
type b (Polyribitol phosphate) = 95% of invasive disease
IgA protease
41
Haemophilus Type B:
SPECTRUM OF DISEASE
Meningitis, Pneumonia, Bacteremia,
Epiglottitis
42
most common cause of epiglottitis
Characteristic?
Sign?
HAEMOPHILUS INFLUENZAE
Cherry red epiglottitis
Thumb sign
Omega sign
43
Non-Typeable:
SPECTRUM OF DISEASE
Conjunctivitis, Otitis Media, COPD exacerbation,
Sinusitis
44
HAEMOPHILUS INFLUENZAE
TREATMENT
Ceftriaxone
45
BORDETELLA PERTUSSIS
Gram?
Culture?
Capsule
Oxidase
Urease
• small gram-negative rods
• culture on Bordet-Gengou agar or Regan-Lowe charcoal medium
Capsule +
Oxidase +
Urease -
46
BORDETELLA PERTUSSIS
HABITAT AND TRANSMISSION
• habitat is upper respiratory tract
• transmission via respiratory droplets
47
BORDETELLA PERTUSSIS
PATHOGENESIS
• filamentous hemagglutinin
o pili rod that extends from the surface of B. pertussis, enabling
the bacteria to bind to ciliated epithelial cells of the bronchi
o mediates attachment
• pertussis toxin
o causes ADP-ribosylation
o activates G proteins that increases cAMP resulting in:
§ increased sensitivity to histamine
§ increased insulin release
§ peripheral lymphocytosis
• extracytoplasmic (false) adenylate cyclase
o ‘weakens’ neutrophils lymphocytes and monocytes
o inhibits phagocytosis
• tracheal cytotoxin
o damages ciliated cells
o causes whooping
48
BORDETELLA PERTUSSIS
SPECTRUM OF DISEASE
Incubation period?
Phases?
Pertussis or Tuspirina
• Incubation Period
o 7-10 days
• Catarrhal phase
o 1-2 weeks
o rhinorrhea, malaise, fever, sneezing, anorexia
o ANTIBIOTICS MOST EFFECTIVE
• Paroxysmal phase
o 2-4 weeks
o ‘Whoop’ → burst of non-productive coughs
o Increased number of lymphocytes in blood smear
o ANTIBIOTICS INEFFECTIVE during this stage
• Convalescent stage
o 3-4 weeks (or longer)
o Diminished paroxysmal cough
o Development of secondary complications (pneumonia,
seizure, encephalopathy)
49
BORDETELLA PERTUSSIS
TREATMENT
PREVENTION
Erythromycin
acellular vaccine in combination with diphtheria and tetanus
toxoids (DTaP)
50
LEGIONELLA PNEUMOPHILA
Gram?
Culture?
• poorly gram-negative rods
o visualize with silver stain
• facultative intracellular bacteria
• culture on charcoal yeast extract agar
o increased amounts of iron and cysteine
o optimal 28 to 40°C; dormant below
20°C and
killed above 60°C
51
Urine antigen test
only detects
L. pneumophilia serogroup 1
52
FACULTATIVE INTRACELLULAR BACTERIA
Salmonella
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia
53
LEGIONELLA PNEUMOPHILA
HABITAT AND TRANSMISSION
natural water environments
transmission via inhalation from aerosols
54
LEGIONELLA PNEUMOPHILA
predisposing factors
o old age, smoking, high alcohol intake, immunosuppression
55
Legionnaires’
Clinical
features
Radiographic
pneumonia
Incubation
period
Pneumonia
Cough
Fever
Yes - hazy infiltrates
2-14 days after exposure
56
Pontiac Fever
Clinical
features
Radiographic
pneumonia
Incubation
period
Flu-like illness
Without pneumonia
No
24-72 hrs afterexposure
57
23/M fishpond cleaner developed fever, cough, and body weakness. If you are suspecting Pontiac fever because of the occupational history, which of the following CXR findings would you expect?
a. Hazy infiltrates on upper and middle lobes
b. Consolidation, empyema, pneumatoceles
c. Doughnut signs
d. Negative chest
d. Negative chest
58
ESCHERICHIA COLI
Gram
Lactose
Antigen
• facultative gram-negative rods
• lactose-fermenting colonies on
EMB or MacConkey agar
• green sheen on EMB agar;
metallic sheen
• typing by O and H antigens
59
ESCHERICHIA COLI
HABITAT AND TRANSMISSION
• habitat is human colon
• colonizes the vagina and urethra
• transmission
o ascending infection in UTI
o during birth in neonatal meningitis
o fecal–oral route in diarrhea
60
ESCHERICHIA COLI
PATHOGENESIS
• pili or fimbriae – attachment, colonization factor, associated
with UTI (cystitis, pyelonephritis)
• flagellum (H)
• capsule (K) – associated with pneumonia and neonatal meningitis (K1)
• endotoxin (O)
• enterotoxins
o ST and LT cause watery diarrhea, increase cAMP (similar to
cholera toxin)
o verotoxin (Shiga-like toxin) causes bloody diarrhea (HUS),
inhibits protein synthesis by inactivating the 60S subunit
of eukaryotic cells (E. coli O157:H7, STEC, EHEC)
61
E.COLI ENTEROTOXIN
ST: cGmp
LT: cAmp
62
ENTEROBACTERIACEAE
Think MESSY SPECK!
Enterobacteria drink COFFEe!
Morganella Serratia
Escherichia Proteus
Shigella Enterobacter
Salmonella Citrobacter
Yersinia Klebsiella
Capsular antigen (K)
O antigen
Flagellar antigen (H)
Ferments glucose
Enterobacteriaceae
63
most common cause of community-acquired UTI
ESCHERICHIA COLI
64
2nd most common cause
ESCHERICHIA COLI
65
NEONATAL MENINGITIS
S – L – E
S. agalactiae (GBS)
Listeria monocytogenes
Escherichia coli
66
Enterotoxigenic
E. coli (ETEC)
Aka
Syndrome
Unique
Site
Toxin
Montesumas revenge
Travellers diarrhea
Watery diarrhea
Cholera-like manifestation
Small intestine
Heat labile -inc camp
Stable toxin -inc cgmp
67
Enteropathogenic
E. coli (EPEC)
Syndrome
Unique
Site
Toxin
Watery diarrhea
infants
Small
Intestine
No toxin
produced.
Flattens villi.
68
Enterohemorrhagic
E. coli (EHEC)
Aka
Syndrome
Unique
Site
Shiga like toxin e coli (stec)
Hamburger
O157; H7
Bloody diarrhea; hemorrhagic colitis
and hemolytic
uremic syndrome
(HUS)
Has shiga-like
toxin/ verotoxin STX 1 and STX 2
Large intestine
Undercooked meat
69
Enteroinvasive
E. coli (EIEC)
SYNDROME
Unique
Bloody diarrhea
Dysentery
Mucus, fever, pus
Shigella-like manifestation
Large intestine
Enterotoxin
70
Enteroaggregative
E. coli (EAEC)
Syndrome
Unique
Persistent watery
diarrhea in children
and patients infected
with HIV
Prolonged
Entero-
aggregative
heat-stable
71
Loss of water and electrolytes
ETEC
72
Flattening of villi
Less absorption of water
EPEC
73
- protein synthesis at 60 ribosomal subnit
EHEC/STEC
74
Flattening of villi + aggregation
Less absorption of water
EAEC
75
Destruction of enterocyte tissue inflam process
EIEC
76
Same with EAEC
Diffused aggregative e.coli
77
Hemolytic Uremic Syndrome
_____ is the most prominent serotype
Triad of:
O157:H7
hemolytic anemia, thrombocytopenia, and uremia
78
Pyogenic Liver Abscess
Clinical manifestation?
Most frequent on ____ lobe
_____ if needed
RUQ pain, fever, jaundice
right
Percutaneous aspiration
79
Pyogenic Liver Abscess
Clinical manifestation?
Most frequent on ____ lobe
_____ if needed
RUQ pain, fever, jaundice
right
Percutaneous aspiration
80
ESCHERICHIA COLI
SPECTRUM OF DISEASE
Urinary Tract Infection
Neonatal Meningitis
Intestinal Infections
Hemolytic Uremic Syndrome
Pyogenic Liver Abscess
81
ESCHERICHIA COLI
TREATMENT
• for UTI
• for meningitis and sepsis
• effective in traveler's diarrhea
ampicillin or sulfonamides
3° cephalosporins
rehydration is
82
A 27-year-old male suddenly develops severe abdominal
cramping and bloody diarrhea. The patient reports consuming rare hamburger four days prior to the onset of the symptoms.
Which of the following best describes the toxin-mediated mechanism of this disease process?
A. Depolymerization of actin filaments in gastrointestinal mucosal cells, leading to mucosal cell death
B. Increased intracellular cAMP in gastrointestinal mucosal cells, resulting in decreased absorption and increased secretion in the
digestive tract
C. Inhibition of elongation factor-2 (EF-2), resulting in decreased protein synthesis in gastrointestinal mucosal cells
D. Inhibition of the 60S ribosomal subunit, resulting in decreased protein synthesis in gastrointestinal mucosal cells
D. Inhibition of the 60S ribosomal subunit, resulting in decreased protein synthesis in gastrointestinal mucosal cells
83
cause
depolymerization of actin filaments in gastrointestinal mucosal
cells, leading to mucosal cell death (i.e., pseudomembranes)
Exotoxin A and B of Clostridioides difficile
84
increases intracellular cAMP in gastrointestinal
mucosal cells, resulting in decreased absorption and increased
secretion in the digestive tract
Cholera toxin
85
inhibits elongation
factor-2 (EF-2), resulting in decreased protein synthesis in gastrointestinal mucosal cells
Exotoxin A of Pseudomonas aeruginosa
86
Gram-negative rod Lactose fermenter, green sheen
Escherichia coli
87
Gram-negative rods Lactose fermenter, urease positive, ESBL
Klebsiella pneumoniae
88
Gram-negative rods Comma-shaped, motile, oxidase positive
Vibrio cholerae
89
Gram-negative rods Comma-shaped, microaerophilic, Skirrow’s agar
Campylobacter jejuni
90
Gram-negative rods Comma-shaped, urease positive
Helicobacter pylori
91
Gram-negative rods Comma-shaped, urease positive
Helicobacter pylori
92
non-lactose-fermenting, gram negative rods
motile, oxidase negative, H2S producer
Salmonella spp.
93
non-lactose-fermenting, gram negative rods
non-motile, oxidase negative, H2S non producer
Shigella spp.
94
non-lactose-fermenting, gram negative rods
swarming, oxidase negative, H2S producer, urease
Proteus mirabilis
95
non-lactose-fermenting, gram negative rods
oxidase positive, H2S non producer, obligate aerobe
Pseudomonas aeruginosa
96
Lactose fermented rapidly
metallic sheen on differential media; motile; flat, non-viscous colonies
raised colonies, no metallic sheen; often motile; more viscous growth
similar to Enterobacter aerogenes
very viscous, mucoid growth; non-motile
• Escherichia coli
• Enterobacter aerogenes
• Enterobacter cloacae
• Klebsiella pneumoniae
97
Lactose fermented slowly
• Edwardsiella, Serratia, Citrobacter, Arizona, Providencia, Erwinia
98
Lactose not fermented
non-motile; no gas from dextrose
motile; acid and usually gas from dextrose
“swarming” on agar; urea rapidly hydrolyzed
(smell of ammonia)
soluble pigments, blue-green and fluorescing; sweetish smell
• Shigella species
• Salmonella species
• Proteus species
• Pseudomonas species
Providencia
Morganella
99
SALMONELLA SPP.
gram?
lactose?
H2S?
detects antibodies in patient's serum?
cultured in?
• facultative gram-negative rods
• non-lactose-fermenting
• produces H2S
• Widal test detects antibodies in patient's serum
• cultured in XLD medium
100
HABITAT
S. typhi
S. enteritidis
• human colon only (S. typhi)
• enteric tract of humans and animals, e.g., chickens and domestic livestock (S. enteritidis)
101
SALMONELLA TRANSMISSION
fecal–oral route
102
SALMONELLA
Enterocolitis
o invasion of
o infectious dose is
o lowers the infectious dose
significantly
o incubation period of
o onset
o fever
o GI symptoms
o Blood cs and stool cs
S. enteritidis/ S. typhimurium
the epithelial and subepithelial tissue of the small and large intestines
high
gastrectomy or use of antacids
12–48 hours
Abrupt, low fever
nausea, vomiting and then progresses to abdominal pain and nonbloody diarrhea
Blood cs neg
Stool cs positive after onset
103
Typhoid Fever
o due to
o organisms enter, multiply in ___ and then spread
to ____
o predilection for invasion of the ___, which can result
in establishment of the ___
o incubation period average of (Jawetz), ranges from (Harrisons)
PARAMETER
Most sensitive diagnostic modality, but rarely indicated in clinical practice
Blood and stool cs?
S. typhi
Vi (virulence) capsular antigen
Peyer patches, reticulo-endothelial system
gallbladder, chronic carrier state
10-14 days
5-21 days
Stepwise pattern fever,
Rose spots -Faint, salmon-colored, blanching, maculopapular rash (trunk and chest) Evident at the end of 1st week, resolves
without a trace after 2-5 days Can have 2-3 lesion crops Salmonella can be cultured from biopsy
Bone marrow
culture
Blood cs positive 1st to 2nd wks
Stool cs negative earlier, positive 2nd wk
104
SALMONELLA
Septicemia
most common sequelae
commonly in patients with
Onset
Fever
GI symptoms
Blood culture
S. choleraesuis
osteomyelitis, pneumonia, and meningitis as the most
common sequelae
o commonly in patients with sickle cell anemia or cancer
Abrupt
Rapid rise then spiking septic temp
None
Positive during high fever
105
Patient came in due to persistent profuse diarrhea,
undocumented fever, and vomiting. Blood culture negative, stool
culture positive during the initial and follow up examinations.
What is the organism is most likely found in the STOOL culture?
A. S. typhi
B. S. enteritidis
C. S. choleraesuis
D. ALL ARE POSSIBLE
B. S. enteritidis
106
Patient came in due to cough, colds, fever, chills, headache, nuchal
rigidity, and vomiting. Denied any diarrhea or constipation. What
is the organism is most likely found in the BLOOD culture?
A. S. typhi
B. S. enteritidis
C. S. choleraesuis
D. ALL ARE POSSIBLE
C. S. choleraesuis
107
Blood culture negative + stool culture positive =
ENTEROCOLITIS
108
Bacteremia with focal lesion (lungs, meninges, etc.) WITHOUT GI
involvement =
SEPTICEMIA
109
TYPHOID FEVER MANAGEMENT:
Ceftriaxone 2-3g IV q24h to
Cefixime 200mg 1tab q12h for 14 days
Azithromycin 1g IV q24h to Azithromycin 500mg 1 tab q24h for 7 days
Ciprofloxacin 400 mg IV q12h to Ciprofloxacin 500-750mg q12h for
14 days
Ofloxacin 400 mg IV
q12h to Ofloxacin 400mg 1
tab q12h for 14 days
110
SALMONELLA
TREATMENT
• Ceftriaxone
• Philippines: Amoxicillin, Chloramphenicol, Co-Trimoxazole
111
An 8-year-old African male with sickle cell anemia develops
osteomyelitis. Which is the most likely etiology?
A. Streptococcus
B. Salmonella
C. Pseudomonas
D. Candida
B. Salmonella
112
OSTEOMYELITIS IN SPECIFIC CONDITIONS
Burns
IV drug abusers
Sickle cell anemia
Pseudomonas aeruginosa
Staphylococcus aureus
Pseudomonas aeruginosa
Salmonella choleraesuis
113
SHIGELLA SPP.
• lactose? gram?
• gas?
• H2S?
• motile?
• antigen?
• cultured in?
• non-lactose-fermenting, gram-negative rods
• produce no gas from the fermentation of glucose
• do not produce H2S
• nonmotile
• have O antigens
• cultured in XLD medium
114
SHIGELLA
HABITAT and TRANSMISSION
• human colon only
• fecal–oral route
4 Fs: Food, Fingers, Feces, Flies
115
SHIGELLA
o Invades?
o Infective dose?
o Invasion of this cell is key to pathogenicity?
submucosa of intestinal tract (distal ileum and
colon)
→ local inflammation
with ulceration
→ bleeding
o Shigella has a low infective dose (103 organisms)
→ it is highly infectious
o mucosal epithelial cells (M cells)
116
most common cause of bacillary dysentery
Shigella sonnei – Duval’s bacillus
117
most severe form of bacillary dysentery
Shigella dysenteriae type 1 – Shiga bacillus
118
most common cause of epidemic dysentery
Shigella dysenteriae type 1 – Shiga bacillus
119
most common cause of epidemic dysentery
120
SHIGELLA
Group A
Shigella dysenteriae
Type 1 Shiga bacillus
Type 2 Schmitz bacillus
121
SHIGELLA
Group B
Shigella flexneri
Flexner bacillus;
Hiss & Russell
bacillus
122
SHIGELLA
Group C
Shigella boydii
Newcastle
Manchester bacillus
123
SHIGELLA
Group D
Shigella sonnei
Duval bacillus
124
Bacillary Dysentery
o incubation period:
o manifestation
o diarrhea frequently resolves in
TREATMENT
1–4 days
fever and abdominal cramps, followed by diarrhea, initially
watery then bloody
2 or 3 days
• fluid and electrolyte replacement
• in severe cases, ciprofloxacin
125
a case of bloody
diarrhea + abdominal pain + SENSORIUM CHANGES
Due to?
Shigella cases
to distant effect of enterotoxin acting as neurotoxin
126
VIBRIO
• shaped? gram?
• motile?
• oxidase?
• cultured on?
• pandemics caused by?
• comma-shaped gram-negative rods
• motile, shooting star motility
• oxidase-positive
• thiosulfate citrate bile salts sucrose (TCBS) agar
• Vibrio cholerae O1 biotype El Tor (cholera El Tor)
127
VIBRIO
HABITAT
TRANSMISSION
HABITAT
• human colon only (V. cholerae)
• saltwater (V. parahaemolyticus and V. vulnificus)
TRANSMISSION
• fecal–oral route (V. cholerae)
• contaminated raw seafood (V. parahaemolyticus)
• trauma to skin, especially in shellfish handlers, or by ingestion of raw shellfish (V. vulnificus)
128
VIBRIO
PATHOGENESIS
• acts by ADP ribosylation
• interacts with the GM1 ganglioside, promotes entry
of subunit A
• increases cAMP leading to prolonged hypersecretion
• enhances attachment to the intestinal mucosa
enterotoxin (Choleragen)
Subunit B
Subunit A
mucinase
129
ADP-ribosylation leads to stimulated Gs protein →
increased cAMP
Choleragen
130
ADP-ribosylation of Gi protein → inhibits Gi (inhibits
inhibitory) → increased cAMP
Pertussis
131
VIBRIO
SPECTRUM OF DISEASE
Cholera
Gastroenteritis
Wound Infections
132
Cholera
o characteristic of diarrhea?
o hypovolemia?
eyes? mouth? skin? skin turgor? hands and feet?
o complications?
o watery diarrhea in large volumes (rice-water stools)
o patients with severe hypovolemia may have sunken eyes, dry
mouth, cold clammy skin, decreased skin turgor, or
wrinkled hands and feet, aka ‘washerwoman's hands’
o complications
§ cardiac and renal failure
§ non-gap acidosis
§ hypokalemia
133
VIBRIO
TREATMENT
Cholera
V. parahaemolyticus, V. vulnificus Infection
Cholera
o fluid and electrolyte replacement
o tetracycline or azithromycin shortens duration
V. parahaemolyticus, V. vulnificus Infection
o minocycline plus fluoroquinolone or cefotaxime
134
CAMPYLOBACTER JEJUNI
• shape? gram?
• aerophilic?
• oxidase?
• catalase?
• grows well at?
• comma-shaped gram-negative rods
“sea gull wing”
• microaerophilic
• positive oxidase and catalase tests
• grows well at 42°C on Skirrow agar
135
most common cause of bacterial gastroenteritis
CAMPYLOBACTER JEJUNI
136
CAMPYLOBACTER JEJUNI
HABITAT AND TRANSMISSION
• habitat is human and animal feces (cattle, chickens, and dogs)
• transmission is by the fecal–oral route
137
CAMPYLOBACTER JEJUNI
PATHOGENESIS
• Organism multiplies in
• Invades the _____ -> inflammation resulting in appearance of _____ in stool
• small intestine
• Invades the epithelium -> inflammation resulting in appearance of RBCS and WBCs in stool
138
may mimic ulcerative colitis
CAMPYLOBACTER JEJUNI
139
CAMPYLOBACTER JEJUNI
disease associations
o Guillain-Barré syndrome
o reactive arthritis (Reiter syndrome)
140
most commonly identified
cause of GBS
CAMPYLOBACTER
141
Guillain-Barré syndrome
§ antigenic cross-reactivity between _____ in
bacterial capsule and _____ on surface of neural
tissues
oligosaccharides
glycosphingolipids
142
Guillain-Barré syndrome
§ antigenic cross-reactivity between _____ in
bacterial capsule and _____ on surface of neural
tissues
oligosaccharides
glycosphingolipids
143
REITER SYNDROME
Triad
Triad of urethritis, uveitis, and arthritis
CAN’T PEE
CAN’T SEE
CAN’T CLIMB A TREE
144
CAMPYLOBACTER
TREATMENT
erythromycin for severe disease- therapy shortens duration of fecal shedding of bacteria
145
HELICOBACTER PYLORI
• shape? gram?
• urease?
• aerophilic?
• curved gram-negative rods
• urease-positive
• microaerophilic
146
UREASE-POSITIVE BACTERIA
Particular Kinds Have Urease.
Proteus mirabilis
Klebsiella pneumoniae
Helicobacter pylori
Ureaplasma urealyticum
147
HELICOBACTER
HABITAT AND TRANSMISSION
• habitat is the human stomach
• transmission is by ingestion
148
HELICOBACTER
PATHOGENESIS
• damages ___ of the gastric mucosa
• production of large amounts of ______ from urea by the organism's urease
o also neutralizes stomach acid, allowing the
organism to survive
• detected using the following tests:
goblet cells
ammonia
o EGD with biopsy showing H. pylori
o urease breath test
o H. pylori stool antigen
149
HELICOBACTER PYLORI SPECTRUM OF DISEASE
• Disease Associations
• Peptic Ulcer Disease
o recurrent pain in the
upper abdomen,
frequently
accompanied by
bleeding into the
gastrointestinal
tract
o gastric carcinoma
o MALT lymphomas
150
H. PYLORI ERADICATION THERAPY
• Triple therapy: Amoxicillin (Metronidazole if with penicillin
allergy) + Clarithromycin + PPI
• Bismuth-based quadruple therapy (if concerned with
macrolide resistance): Bismuth + PPI + Metronidazole +
Tetracycline
151
KLEBSIELLA PNEUMONIAE
• urease?
• gram?
• activity in drug- resistant strains?
• urease-positive; facultative gram-negative rods with large polysaccharide capsule
• extended spectrum beta-lactamase (ESBL) activity in drug- resistant strains
152
KLEBSIELLA PNEUMONIAE
HABITAT
TRANSMISSION
• upper respiratory and
GIT
• aspiration or inhalation
• ascending spread of fecal flora
153
most common cause Pneumonia in alcoholics
KLEBSIELLA PNEUMONIAE
154
KLEBSIELLA PNEUMONIAE
SPECTRUM OF DISEASE
TREATMENT
• Pneumonia
thick, bloody sputum ("currant-jelly" sputum)
o usually nosocomial
o most common cause in alcoholics
• Urinary Tract Infections
• culture-guided treatment (cephalosporins alone or with
aminoglycosides)
155
PROTEUS MIRABILIS
• gram?
• lactose?
• urease?
• motile?
• facultative gram-negative rods
• non-lactose-fermenting
• urease-positive
• swarming motility
156
PROTEUS MIRABILIS
PATHOGENESIS
hydrolyzes the urea in urine to form ammonia
Urine ph?
Stone?
• urease hydrolyzes the urea in urine to form ammonia
o raises pH producing alkaline urine
o encourages the formation of struvite stones, composed of magnesium-ammonium-phosphate
157
PROTEUS MIRABILIS
SPECTRUM OF DISEASE
Complicated Urinary Tract Infection
o UTI associated with nephrolithiasis
o staghorn calculi form on renal calyces
158
PROTEUS
TREATMENT
• TMP-SMX or ampicillin
• surgery for large stones
159
PSEUDOMONAS AERUGINOSA
Aka?
• gram?
• aerobe?
• lactose
• oxidase
• pigment? odor?
• grown on?
Blue pus
• gram-negative rods
• obligate aerobe
• non-lactose-fermenting
• oxidase-positive
• pyocyanin (blue-green pigment), sweet grape-like odor
• grown on Cetrimide agar
160
PSEUDOMONAS
HABITAT AND TRANSMISSION
• environmental water sources, e.g., in hospital respirators and
humidifiers
• inhabits the skin, upper respiratory tract, and colon of about
10% of people
• transmission via water aerosols, aspiration, and fecal contamination
161
PSEUDOMONAS
PATHOGENESIS
tissue necrosis and inactivates EF-2
type III secretion system facilitates exotoxin transfer
damages the cilia and mucosal cells
from hemoglobin breakdown → any of several green compounds derived from hemoglobin or related compounds by cleavage of the porphyrin ring
• endotoxin
• exotoxin A
o tissue necrosis and inactivates EF-2
o type III secretion system facilitates exotoxin transfer
• elastase and proteases
• pyocyanin damages the cilia and mucosal cells
• verdoglobin from hemoglobin breakdown → any of several green compounds derived from hemoglobin or related compounds by cleavage of the porphyrin ring
162
PSEUDOMONAS
SPECTRUM OF DISEASE
• Skin and Soft Tissue Infections
o burn wound infections
o hot tub folliculitis → typically self-limiting
§ spa pools, whirlpools, or inadequately chlorinated
swimming pools and hot tubs (Remember: Pseudomonas
loves ‘wet’ environments)
o skin graft- loss due to infection
o green nail syndrome
163
PSEUDOMONAS
SPECTRUM OF DISEASE
Bone and Cartilage Infections
o puncture wound osteomyelitis
o pubic osteomyelitis in IV drug abusers
164
PSEUDOMONAS
SPECTRUM OF DISEASE
Ear Infections
o otitis externa
o malignant otitis externa in diabetics
o chronic suppurative otitis media
165
PSEUDOMONAS
SPECTRUM OF DISEASE
Pneumonia
o ventilator-acquired pneumonia
o high-risk CAP
§ immunocompromised
§ broad spectrum antibiotics
§ steroid therapy
§ structural lung lesions: bronchiectasis, cystic fibrosis
166
PSEUDOMONAS
SPECTRUM OF DISEASE
Gastrointestinal Infections
o typhlitis (necrotizing enterocolitis)
o Shanghai fever (mild form of typhoid)
o peritonitis in patients undergoing peritoneal dialysis
167
3rd most common cause of nosocomial UTIs
PSEUDOMONAS AERUGINOSA
168
3rd most common cause of nosocomial UTIs
PSEUDOMONAS AERUGINOSA
169
PSEUDOMONAS
SPECTRUM OF DISEASE
Sepsis
o ecthyma gangrenosum
§ hemorrhagic lesions
o febrile neutropenia
§ leukemia or lymphoma post chemo- or radiation therapy
§ severe burns
170
PSEUDOMONAS
TREATMENT
combination of active antibiotics required because of
resistance to multiple antibiotics
o antipseudomonal penicillins (ticarcillin, piperacillin)
o penicillin plus beta-lactamase inhibitor (ticarcillin-
clavulanate, piperacillin-tazobactam)
o third generation cephalosporins (ceftazidime)
o fourth generation cephalosporins (cefepime)
o monobactam (aztreonam)
o carbapenems (imipenem, meropenem)
o fluoroquinolones (ciprofloxacin)
171
PSEUDOMONAS
TREATMENT
combination of active antibiotics required because of
resistance to multiple antibiotics
o antipseudomonal penicillins (ticarcillin, piperacillin)
o penicillin plus beta-lactamase inhibitor (ticarcillin-
clavulanate, piperacillin-tazobactam)
o third generation cephalosporins (ceftazidime)
o fourth generation cephalosporins (cefepime)
o monobactam (aztreonam)
o carbapenems (imipenem, meropenem)
o fluoroquinolones (ciprofloxacin)
172
BACTEROIDES FRAGILIS
• aerobic? gram?
• predominant anaerobe of?
• spreads to blood or peritoneum during ___
• anaerobic, gram-negative rods
• predominant anaerobe of human colon
• spreads to blood or peritoneum during bowel trauma, perforation or surgery
173
BACTEROIDES FRAGILIS
PATHOGENESIS
• infections commonly due to combinations of bacteria in _____
• endotoxic activity?
• capsule?
• foul-smelling discharge → because of short-chain fatty-acid products of fermentation
• synergistic pathogenicity
• LPS with low endotoxic activity
• capsule (antiphagocytic and anticomplement)
• smell?
174
BACTEROIDES
SPECTRUM OF DISEASE
• abdominal abscess
• peritonitis
175
BACTEROIDES
TREATMENT
• metronidazole, clindamycin or cefoxitin
• surgical drainage of abscess
176
BACTEROIDES
TREATMENT
• metronidazole, clindamycin or cefoxitin
• surgical drainage of abscess
