Infectious Diseases Flashcards
Criteria for Fever of Unknown Origin (FUO)
rectal T ≥ 38° C
cause could not be identified
3 weeks - OPD
1 week - hospital
FUO in Neonates
7% risk of having serious bacterial infection
FUO at 1-3 mos.
pyelonephritis - most common
FUO at 3 mos. - 3 y.o.
viral infection
_____ are connective tissue diseases most commonly associated with FUO.
JIA, SLE
Empirical treatment for FUO should be avoided except in _____.
anti-TB drugs for the critically ill
_____ is an aerobic, G (+), coagulase (+) bacteria that grows in pairs or clusters.
Staphylococcus aureus
_____ is the most common cause of pyogenic infection of the skin and soft tissue
S. aureus
Adhesion of S. aureus to mucosal cells is mediated by _____ in the cell wall.
teichoic acid
Staphylococci produce a _____ which may interfere with opsonophagocytosis.
slime layer
loose polysaccharide capsule
_____ is present in S. aureus and absorbs serum Ig, preventing antibacterial antibodies from acting as opsonins.
Protein A
Enzymes Elaborated by Staphylococci
catalase
penicillinase or β-lactamase
_____ is a protein than S. aureus combines with phospholipid in the leukocytic cell membrane, producing increased permeability and eventual death of the cell.
Panton-Valentine Leukocidin (PVL)
S. aureus with _____ is associated with more severe and invasive skin disease, pneumonia and osteomyelitis.
Panton-Valentine Leukocidin (PVL)
_____ in S. aureus produce dermatologic manifestations by splitting the desmosome and altering the intracellular matrix in the stratum granulosum.
Exfoliatins A and B
S. aureus can produce _____ distinct enterotoxins.
≥ 20
_____ are the most common causes of food poisoning from S. aureus.
Enterotoxin A and B
_____ is associated with TSS related to menstruation and focal staphylococcal infection.
Toxic Shock Syndrome Toxin 1 (TSST-1)
_____ is a superantigen from S. aureus that induces the production of IL-1 and TNF, resulting in hypotension, fever and multisystem involvement.
Toxic Shock Syndrome Toxin 1 (TSST-1)
An altered _____ is responsible for the methicillin resistance of MRSA isolates.
PBP-2A
protein binding proteins
_____ that complicates viral croup may be caused by S. aureus.
Membranous Tracheitis
S. aureus often causes _____ that may be associated with empyem, pneumatocoeles, pyopneumothorax and bronchopleural fistulas.
necrotizing pneumonitis
Localized staphylococcal abscesses in muscle is called _____.
pyomyositis.
_____ is the most common cause of osteomyelitis and suppurative arthritis in children.
S. aureus
_____ is an acute and potentially severe illness caharcterized by fever, hypotension, erythematous rash with dezquamation of the hands and feet, vomiting, diarrhea, neurologic abnormalities, myalgia, conjuctival hyperemia, and strawberry tongue.
Toxic Shock Syndrome (TSS)
TSS occurs most commonly in _____
menstruating women 15-25 y.o.
Diagnostic Criteria of Staphylococcal TSS
Major Criteria (all are required)
- acute fever (> 38.8°C)
- hypotension
- rash (erythroderma with convalescent desquamation)
Minor Criteria (≥ 3)
- thrombocytopenia (≤ 100,000)
- mucus membrane inflammation
- vomiting, diarrhea
- liver abnormalities
- renal abnormalities
- muscle abnormalities
- CNS abnormalities
Diagnostic Criteria of Staphylococcal TSS: Major Criteria (all are required)
acute fever (> 38.8°C)
hypotension
rash (erythroderma with convalescent desquamation)
Diagnostic Criteria of Staphylococcal TSS: Minor Criteria (≥ 3)
thrombocytopenia (≤ 100,000) mucus membrane inflammation vomiting, diarrhea liver abnormalities renal abnormalities muscle abnormalities CNS abnormalities
Toxic Shock Syndrome (TSS) Treatment
β-lactamase-resistant antistaphylococcal antibiotic (Nafcillin, Oxacillin, 1st generation Cephalosporin)
Vancomycin (MRSA)
Clindamycin (reduces toxin production)
_____ infections are common in patients with indwelling foreign devices.
Coagulase Negative Staphylococci (CoNS)
_____ are the most common cause of nosocomial infection, especially in NICU.
CoNS
_____ is the most common and persistent species of CoNS.
S. epidermidis
CoNS, specifically S. epidermidis, are the most common cause of nosocomial bacteremia associated with _____.
central venous catheter
CoNS is a common cause of _____ endocarditis.
prosthetic valve.
_____ is the most common pathogen found in CSF shunt meningitis.
CoNS
_____ is a common cause of primary UTI in sexually active females.
S. saprophyticus
True bacteremia with CoNS is considered when there is _____.
growth within 24 hours
≥ 2 cultures with same strain
both peripheral and line sites are (+)
Most CoNS strains are resistant to _____.
Methicillin
_____ is a G (+), lancet-shaped, bile soluble, optochin sensitive, polysaccharide encapsulated diplococcus, occurring as individual cocci or in chains.
Streptococcus pneumoniae
_____ is the most common cause of bacteremia, bacterial pneumonia, otitis media and bacterial meningitis in children.
S. pneumoniae
Encapsulated strains cause most serious diseases because _____ impede phagocytosis.
capsular polysaccharides
S. pneumoniae is a common cause of secondary bacterial pneumonia in children with _____.
influenza
Patients with _____ are susceptible to encapsulated organisms because of deficient opsonization and clearance of bacteria.
asplenia
A _____ should be performed when a pneumococcus is resistant to Erythromycin but sensitive to Clindamycin.
D-test
induce Clindamycin resistance
Immunologic responsiveness and efficacy following administration of pneumococcal polysaccharide vaccines is unpredicaatable in children _____.
< 2 y.o.
_____ prophylaxis is recommended for children at high risk of invasive pneumococcal disease, including children with asplenia or sickle cell disease.
Penicillin
Group A Streptococcus (GAS) is also known as _____.
Streptococcus pyogenes
_____ causes distinct clinical entities such as scarlet fever and erysipelas.
S. pyogenes (GAS)
S. pyogenes (GAS) causes 2 nonsuppurative complications:
Rheumatic Fever
Acute Glomerulonephritis
_____ are G (+) coccoid-shaped bacteria that grow in chains.
S. pyogenes (GAS)
Virulence of S. pyogenes (GAS) depends on the _____ which resists phagocytosis.
M protein
Streptococcal pyoderma occurs most frequently in _____ temperatures.
warmer
Streptococcal _____ are responsible for the rash of scarlet fever.
pyrogenic exotoxins A, B and C
_____ is an URTI associated with a characteristic rash which begins around the neck and spreads over the trunk and extremities.
Scarlet Fever
The rash of scarlet fever appears within _____ after onset of symptoms.
24-48 hours
After _____, the rash of scarlet fever begins to fade and is followed by desquamation starting with the _____.
3-4 days
face progressing to the trunk
A diffuse, finely papular rash with erythematous eruption which blanches on pressure is characteristic of _____.
Scarlet Fever
A _____ tongue is usually seen in Scarlet Fever.
strawberry tongue
_____ is a GAS infection which involves the deeper layer of skin and connective tissue with a sharply defined slightly elevated border.
Erysipelas
The gold standard for the confirmation of GAS pharyngitis is _____.
throat swab culture on a sheep blood agar plate
S. pyogenes (GAS) is very sensitive to _____.
Penicillin
_____ is a superficial S. pyogenes (GAS) skin infection that appears as an erythematous papulovesicular lesion which becomes purulent and covered with an amber-colored crust which appears to be stuck onto the skin.
Non-bullous Impetigo
_____ is a S. pyogenes (GAS) skin infection with flaccid, transparent bullae < 3 cm in diameter.
Bullous Impetigo
S. pyogenes (GAS) is a common cause of vaginitis in _____.
prepubertal girls
Criteria for Streptococcal TSS
Hypotension plus ≥ 2 of the ff.:
- renal impairment
- coagulopathy
- hepatic involvement
- adult respiratory distress syndrome
- generalized erythematous macular rash
- soft-tissue necrosis
Severe Invasive GAS Infections
Streptococcal TSS
Necrotizing Fasciitis
_____ is characterzized by the onset of acute arthritis following an episode of GAS pharyngitis in a patient whose illness does not fulfill the Jones criteria.
Poststreptococcal Reactive Arthritis (PSRA)
_____ is a group of neuropsychiatric disorders (OCD, tic disorder, Tourette Syndrome) for which a possible relationship with GAS infections has been hypothesized.
Pediatric Autoimmune Neuropsychiatric Disorders Associated with S. Pyogenes (PANDAS)
When therapy against GAS is given within _____ of onset, acute rheumatic fever is prevented.
9 days
_____ is the most common form of acquired heart disease.
Rheumatic Heart Disease
_____ is most closely associated with the incidence of acute rheumatic fever.
Crowding
A property of GAS that has been associated with rheumatogenicity is the formation of _____.
highly mucoid colonies
Children _____ are at greatest risk for GAS pharyngitis.
5-15 y.o.
Cytotoxic Theory of the Pathogenesis of ARF and RHD
GAS toxin Streptolysin O (direct cytotoxic effect on cells)
Immunologic Theory of the Pathogenesis of ARF and RHD
common antigenic determinants shared between GAS and mammalian tissue (M protein ↔ tropomyosin, myosin)
Criteria for Acute Rheumatic Fever
Jones Criteria 5 Major Criteria - migratory polyarthritis - carditis - subcutaneous nodules - erythema marginatum - Sydenham chorea
4 Minor Criteria
- arthralgia
- fever
- elevated ESR and CRP
- prolonged PR interval
*2 major, 1 major + 2 minor
_____ is the most serious manifestation of ARF.
Carditis
_____ is a universal finding in ARF.
Endocarditis (Valvulitis)
_____ is the earliest manifestation of ARF and has an inverse relationship with the severity of cardiac involvement.
Migratory Polyarthritis
In ARF< there is a correlation between the presence of subcutaneous nodules and significant _____.
Rheumatic Heart Disease
Clinical Maneuvers for Chorea
- Milkmaid’s Grip (irregular contractions while squeezing examiner’s hand)
- spooning and pronation of hands when extended
- wormian darting movements of tongue on protrusion
- handwriting
Absolute Requirements for Evidence of GAS Infection
(+) throat culture or rapid streprococcal antigen test
elevated or increasing streptococcal antibody titer
ARF without adherence to Jones Criteria can be made when there is _____
Chorea as the only manifestation
Indolent Carditis as the only manifestation
Recurrent ARF
Treatment for ARF
Oral Penicillin or Erythromicin x 10 days
IM Benzathine Penicillin as single dose
Anti-inflammatory agents should be withheld if arthralgia or atypical arthritis is the only clinical manifestation. _____ may be used instead
Acetaminophen
ARF patients with typical migratory polyarthritis and those with carditis without cardiomegaly or CHF should be given _____
oral salicylates
Aspirin:
100 mkday q6 x 3-5 days then
75 mkday q6 x 4 weeks
ARF patients with carditis and cardiomegaly or CHF should be given _____.
corticosteroids
Prednisone:
2 mkday q6 x 2-3 weeks then
tapered by 5 mg/day ever 2-3 days
_____ is the treatment of choice for Sydenham chorea.
Phenobarbital 16-32 mg q6-8 PO
_____ is the regimen of choice for ARF antibiotic prophyhlaxis.
IM Benzathine Penicillin every 4 weeks
600,000 IU - ≤ 60 lbs
1.2 M IU - > 60 lbs
ARF Antibiotic Prophyhlaxis:
RF without carditis
5 years or until 21 y.o.
ARF Antibiotic Prophyhlaxis:
RF with carditis but without residual heart disease
10 years or until 21 y.o.
ARF Antibiotic Prophyhlaxis:
RF with carditis and residual heart disease
10 years or until 40 y.o. or lifelong
Group B Streptococcus (GBS) is also known as _____.
Steptococcus agalactiae
S. agalactiae (GBS) is a major cause of _____.
neonatal sepsis
_____ are facultative anaerobic G (+) cocci that form chains or diplococci in broth and small gray-white colonies on solid medium.
S. agalactiae (GBS)
Presumptive Identification of S. agalactiae (GBS)
β-hemolysis on blood agar
resistance to Bacitracin and TMP-SMX
lack of hydrolysis of bile esculin
elaboration of CAMP factor
Early Onset GBS Disease:
Age at Onset
0-6 days
Early Onset GBS Disease:
Increased Risk after Obstetric Complication
No
Early Onset GBS Disease:
Clinical Manifestations
sepsis, pneumonia, meningitis
Early Onset GBS Disease:
Common Serotypes
Ia, Ib, II, III, V
Early Onset GBS Disease:
Case Fatality Rate
4.7%
Late Onset GBS Disease:
Age at Onset
7-90 days
Late Onset GBS Disease:
Increased Risk after Obstetric Complications
No
Late Onset GBS Disease:
Clinical Manifestations
bacteremia, meningitis, focal infections
Late Onset GBS Disease:
Common Serotypes
III
Late Onset GBS Disease:
Case Fatality Rate
2.8%
GBS Treatment:
Bacteremia without a Focus
10 days
GBS Treatment:
Meningitis
2-3 weeks
GBS Treatment:
Ventriculitis
4 weeks
GBS Treatment:
Septic Arthritis or Osteomyelitis
3-4 weeks
A major risk factor for the development of early-onset GBS infection is _____.
maternal vaginal or rectal colonization by GBS
The foremost risk factor implicated in the pathophysiology of invasive GB disease is the _____.
type-specific capsular polysaccharide
The _____ component of the GBS capsular polysaccharide prevents activation of the alternative pathway in the absence of type-specific antibody.
sialic acid
GBS Virulence Factors:
adhesion to host cells
GBS Surface Protein
GBS Virulence Factors:
inhibit the recruitment of PMN cells
C5a Peptidase
GBS Virulence Factors:
associated with cell injury
β-Hemolysin
GBS Virulence Factors:
spreading factor in host tissue
Hyaluronidase
The _____ of the GBS cell wall are potent inducers of the TNF-α release.
Group B Antigen
Peptidoglycan Component
Invasive GBS disease in children beyond early infancy is uncommon and manifests as _____.
bacteremia
endocarditis
Severe apnea, easly onset of shock, abnormalities in WBC count and greater lung compliance may indicate infants with _____ rather than RDS.
GBS disease
_____ is the recommended treatment for GBS disease.
Penicillin
Interruption of neonatal colonization is achievable if antibiotics are given to the mother during _____.
labor
Intrapartum antibiotics should be given to women with _____.
(+) prenatal screening GBS bacteriuria previous infant with GBS disease unknown culture status delivered prematurely PROM (> 18 hours) intrapartum fever (≥ 38°C)
_____ are G (+), catalase (-) facultatice anaerobes that grow in pairs or short chains.
Enterococci
_____ accounts for 80% of enterococcal infections.
E. faecalis
Diptheria is an acute toxic infection caused by _____.
Corynebacterium diphtheriae
_____ are aerobic, nonencapsulated, non-spore-forming, mostly non-motile, pleomorphic, G (+) bacilli.
Corynebacteria
The virulence of C. diphtheriae lies in its ability to produce the potent _____ which inhibits protein synthesis and causes local tissue necrosis.
65kd polypeptide
Within the first few days of diphtheria, a dense necrotic coagulum of organisms, epithelial cells, fibrin, leukocytes, and erythrocytes forms and becomes a gray-brown leather-like adherent _____.
psudomembrane
The primary focus of respiratory tract diphtheria is the _____.
tonsils or pharynx
_____ causes shallow ulceration of the external nares and upper lip in infants as well as soft tissue edema creating a bull-neck appearance.
respiratory tract diphtheria
_____ presents as a superficial, ecthymic, non-healing ulcer with a gray-brown membrane.
cutaneous diphtheria
_____ causes 50-60% of deaths from diphtheria.
Toxic Cardiomyopathy
Toxic cardiomyopathy in diphteria presents as tachycardia which is _____.
disproportionate to fever
Cranial neuropathies caused by diphtheria occur in the _____ leading to _____.
5th week
oculomotor and ciliary paralysis
In diphtheria, muscle weakness progresses _____.
distal → proximal
_____ is the mainstay treatment for diphtheria.
Anti-Toxin
The role of anti-microbial therapy in diphtheria is to _____.
halt toxin production
treat localized infection
prevent transmission of the organism to contacts
Antibiotics for Diphtheria
Erythromycin
Penicillin
Antibiotics for Diphtheria:
Erythromycin Dose
40-50 mkday q6 PO/IV
*max. 2 g/day
Antibiotics for Diphtheria:
Penicillin G Dose
100,000-150, 000 ukday q6 IV/IM
Antibiotics for Diphtheria:
Procaine Penicillin Dose
300,000 u/day IM - < 10 kg
600,000 u/day IM - > 10 kg
Household contacts of diphtheria should be monitored for illness through the _____.
7-day incubation period
Prophylactic Antibiotics for Diphtheria
Benzathine Penicillin G
Erythromycin
Prophylactic Antibiotics for Diphtheria:
Benzathine Penicillin G Dose
600,000 u IM - < 6 y.o.
1.2 M u - > 6 y.o.
Prophylactic Antibiotics for Diphtheria:
Erythromycin Dose
40-50 mkday QID PO x 10 days
*max. 2 g/day
Diphtheria toxoid vaccine is given to immunized individuals who _____.
have not received a booster dose within 5 years
_____ is a facultatively anaerobic,non-spore-forming, motile, catalase (+), G (+) bacilli
Listeria monocytogenes
_____ are anaerobbic, non-sporulating, g(+) bacteria that are part of the endogenous oral flora in humans and have filamentous and branching structure.
Actinomyces
_____ are G (+) filamentous bacilli which form a beaded pattern along portions of its branching filaments.
Nocardia
_____ is a G (-), fastidious, encapsulated, oxidase (+), aerobic diplococcus occuring in kidney shaped pairs.
Neisseria meningitidis (Meningococcus)
The Meningococcus strains responsible for almost all cases of human disease are _____
A, B, C, W-135, X, Y
N. meningitidis is transmitted via _____.
aerosol droplets
respiratory secretions
Risk Factors for Meningococcal Infection
viral respiratory infections tobacco smoke marijuana use binge drinking night clubs/bars dormitories
_____ are specific bacteria adhesins which mediate the attachment of N. meningitidis to nasopharyngeal mucosal cells.
pili
opacity-associated proteins (Opa, Opc)
The most important virulence determinant of N. meningitidis is the presence of a _____ which enhances resistance to opsonophagocytic killing.
capsular polysaccharide
_____ is essential in stmulating cytokines and activating coagulation and bleeding which are hallmarks of severe meningococcal sepsis.
Endotoxin (lipopolysaccharide)
The _____ portion of the meningococcal lipopolysaccharide is responsible for the toxicity of the molecule.
Lipid A
Diffuse adrenal hemorrhage in fulminant meningococemia is called _____.
Waterhouse-Friderichsen Syndrome
Persons with inherited deficiencies of _____ are 1000x more susceptible to meningococcal infections.
properdin
factor D
terminal complement components
Fulminant meningococcemia progresses rapidly over several hours from fever with non-specific signs to spetic shock with prominent petechiae and purpura called _____.
purpura fulminans
Definitie diagnosis of meningococcal disease is established by _____.
isolation of N. meningitidis from a normally sterile body fluid
_____ are the drugs of choice for N. meningitidis.
β-lactam antibiotics
_____ is the most frequent neurologic sequela of meningococcal meningitis.
Deafness
Poor Prognostic Factors for Meningococcal Infections
hypothermia or severe hyperpyrexia hypotension purpura fulminans seizures leukopenia thrombocytopenia (DIC) acidosis ↑endotoxin and TNF-α petechiae < 12 hrs before admission absence of meningitis low or N ESR
Antibiotic prohylaxis for N. meningitidis is indicated for persons in contact with the patient’s oral secretions _____.
7 days before onset of illness
Antibiotics for N. meningitidis Prophhylaxis
Rifampin
Ceftriaxone
Ciprofloxacin
N. meningitidis Prophhylaxis:
Rifampin Dose
< 1 mo. 5 mkdose PO q12 x2 days
≥ 1 mo. 10 mkdose PO q12 x 2 days
*max. 600 mg PO q12
N. meningitidis Prophhylaxis:
Ceftriaxone Dose
< 15 y.o. 125 mg IM
≥ 15 y.o. 250 mg Im
N. meningitidis Prophhylaxis:
Ciprofloxacin Dose
20 mg/kg PO
- max. 500 mg PO
Meningococcal vaccination is recommended for _____.
11-21 y.o.
Antibody titers for N. meningitidis peak after _____ from vaccination.
4-6 weeks
A N. meningitidis antibody titer of _____ is considered protective.
≥ 1:4
Gonorrhea is transmitted via _____.
sexual contact
perinatal transmission
_____ is a non-motile, aerobic, non-spore forming, G (-) intracellular diplococcus with flattened adjacent surfaces.
Neisseria gonorrhoeae
Gonococcal species are differentiated from other Neiseria species by the _____.
fermentation of glucose but not maltose, sucrose or lactose
2 systems used to characterize gonococcal strains are _____.
auxotyping
serotyping
_____ is based on genetically stable requirements of strains for specific nutrients or cofactors.
Auxotyping
The most widely used Gonococcal serotyping system is based on a porin called _____.
Por1
_____ is the most common STI in sexually abused children.
Gonorrhea
N. gonorrhoeae primarily affects the _____.
columnar apithelium
Gonorrhea can cause endometritis, salpingitis and peritonitis which is collectively known as _____.
pelvic inflammatory disease (PID)
Dissemination of N. gonorrhoeae from the fallopian tubes through the peritoneum to the liver capsule results in perihepatitis called _____.
Fitz-Hugh-Curtis Syndrome
Women are more prone to disseminated gonoccocal infection during _____.
mentruation
pregnancy
postpartum period
The most common initial symptom of disseminated gonoccocal infection is _____.
acute polyarthralgia with fever
Clinical Syndromes of Disseminated Gonoccocal Infection
Tenosynovitis-Dermatitis Syndrome
Suppurative Arthritis Syndrome
Clinical Syndromes of Disseminated Gonoccocal Infection:
more common, fever, chills, skin lesions, polyathralgia, (+) blood CS
Tenosynovitis-Dermatitis Syndrome
Clinical Syndromes of Disseminated Gonoccocal Infection: monoarticular arthritis (knee), (-) blood CS
Suppurative Arthritis Syndrome
In _____, typical necrotic pustules on an erythematous base is distributed evenly over the extremities usually sparing the face and scalp.
disseminated gonoccocal infection
Acute endocarditis leading to rapid destruction of the _____ is an uncommon but fatal manifestation of disseminated gonoccocal infection.
aortic valve
In males, presumptive diagnosis of gonorrhea can be made by _____.
identification of G (-) intracellular diplococci in urethral discharge
All patients with gonorrhea should be tested for concomitant _____.
syphilis
hepatitis B
HIV
C. trachomatis
_____ is recommended as the initial therapy for gonorrhea.
Ceftriaxone
For gonorrheal PID, the recommended treatment therapy is _____.
Cefoxitin + Doxycucline
Gonococcal ophthalmia neonatorium can be prevented by instilling _____ into each conjunctiva shortly after birth.
1% solution of silver nitrate
erythromycin or tetracycline ophthalmic ointment
_____ is the most common etiology of joint and bone infections in children.
Kingella kingae
_____ is a fastidious, facultative anaerobic, β-hemolytic member of the Neisseriaceae family that appears as pairs or short chains of G (-) coccobacilli with tapered ends.
Kingella kingae
_____ is a fastidious, G (-), pleomorphic coccobacillus that requires factor X (hematin) and factor V (phosphorydine nucleotide) for growth.
Haemophilus influenzae
H. influenzae requires _____. for growth.
factor X (hematin) factor V (phosphorydine nucleotide)
In the pre-vaccine era, _____ was a major cause of serious disease among children.
Hib
In Hib meningitis, _____ given shortly before or concurrent with the initiation of antimicrobial therapy decreases the risk of hearing loss.
Dexamethasone
Children with H. influenzae cellulitis have an antecedent _____ due to the seeding of organisms during bacteremia.
URTI
H. influenzae usually affects the _____.
head
neck
cheek
preseptal region
_____ are the most common causes of otitis media.
H. influenzae
S. pneumoniae
Morazella catarrhalis
_____ is the drug of choice for H. influenzae.
Ampicillin
_____ is used when H. influenzae is resistant to Ampicillin.
Ceftriaxone
_____ is preferred for non-invasive H. influenzae infections.
Amoxicillin
_____ is used as antibiotic prophylaxis for H. influenzae.
Rifampin
_____ is an STD characterized by painful genital ulceration and inguinal lyphadenopathy (buboes).
Chancroid (Haemophilus ducreyi)
_____ is an unencapsulated, G (-) diplococcus and is a human specific pathogen that colonizes the respiratory tract beginning in infancy.
Moraxella catarrhalis
_____ is the sole cause of epidemic pertussis and the usual cause of sporadic pertussis.
Bordatella pertussis
_____ is a small, fastidious, G (-) coccobacilli that colonize only ciliated epithelium.
Bordatella pertussis
Pertussis is highly contagious with infection rates as high as _____.
100%
Protection against typical pertussis begins to wane _____ after vaccination.
3-5 years.
The major virulence protein of B. pertussis is the _____.
pertussis toxin
The Pertussis Toxin causes lymphocytosis by _____.
rerouting lymphocytes to remain in the circulationg blood.
Incubation period of Pertussis
3-12 days
Stages of Pertussis
Catarrhal - 1-2 weeks
Paroxysmal - 2-6 weeks
Convalescent - ≥ 2 weeks
Stages of Pertussis:
non-specific symptoms, congestion, rhinorrhea
Catarrhal - 1-2 weeks
Stages of Pertussis:
cough begins as a dry, intermittent, irritative hack and evolves into inexorable paroxysms
Paroxysmal - 2-6 weeks
Stages of Pertussis:
the number, severity and duration of coughing episodess diminish
Convalescent - ≥ 2 weeks
Infants _____ do not display the classic stages of pertussis.
< 3 mos.
Pertussis is characterized by cough ≥ 14 days plus _____>
paroxysms
whooping
post-tussive vomiting
Leukocytosis due to absolute lymphocytosis is characteristic of the _____ of pertusis.
catarrhal stage
Severe course and death from pertussis are correlated with extreme _____.
leukocytosis
thrombocytosis
_____ is the gold standard for diagnosing pertussis.
Isolation of B. pertussis in culture
The preferred culture media for B. pertussis are _____.
Regan-Lowe Charcoal Agar
Stainer-Scholte Media
_____ are the antibiotic of choice for pertussis.
Macrolides (Azithromycin)
Oral erythromycin increases the risk for _____ 7-10x in neonates.
hypertrophic pyloric stenosis
Exposure Prophylaxis for Pertussis:
< 7 y.o. with < 4 doses of pertussis vaccine
complete DTaP series
Exposure Prophylaxis for Pertussis:
< 7 y.o. with 3rd dose of pertussis vaccine 6 mos. before exposure
DTaP booster
Exposure Prophylaxis for Pertussis:
< 7 y.o. with 4th dose of pertussis vaccine 3 years before exposure
DTaP booster
Exposure Prophylaxis for Pertussis:
≥ 9 y.o. without Tdap
Tdap
Antibiotics for Pertussis
Azithromycin
Erythromycin
Clarithromycin
TMP-SMX
Antibiotics for Pertussis:
Azithromycin Dose
0-5 mos. - 10 mkday OD x 5 days
≥ 6 mos. - 10 mkday OD on D1, 5 mkday OD on D2-5
adults - 500 mg OD on D1, 250 mg OD on D2-5
Antibiotics for Pertussis:
Erythromycin Dose
children - 40-50 mkday QID x 14 days
adults - 2 g/day QID x 14 days
Antibiotics for Pertussis:
Clarithromycin Dose
children > 1 mo. - 15 mkday BID x 7 days
adults - 1 g/day BID x 7 days
Antibiotics for Pertussis:
TMP-SMX Dose
children > 2 mos. - TMP 8 mkday + SMX 40 mkday BID x 14 days
adults - TMP 320 mg/day + SMX 1600 mg/day BID x 14 days
_____ are motile, nonsporulating, nonencapsulated, G (-) rods that grow aerobically and are capable of facultative anaerobic growth.
Salmonellae
Sallmonella is resistant to many agents but can be killed by _____.
heating to 130°F for 1 hour or 140°F for 15 min.
Salmonella Antigens
Somatic O
Flagellar H
_____ are the most important serotypes for salmonellosis transmitted from animals to humans.
Salmonella enteritidis
Salmonella typhimurium
_____ Salmonella organisms must be ingested to cause symptomatic disease.
10^6 - 10^8
Gastric acidity inhibits multiplication of the salmonellae and most organisms are killed at _____.
gastric pH ≤ 2
Intestinal Salmonella infection results in a localized enteritis that is associated with a _____ response from the intestinal epithelium.
secretory
Intestinal Salmonella infection induces secretion of _____ and other chemoattractants from the apical surface, directing recruitment and transmigratioon of neutrophils into the gut lumen and thus preventing systemic spread.
IL-8 - basolateral surface
The most common clinical presentation of salmonellosis is _____.
acute enteritis
In Salmonella enteritis, stool typically contains _____.
PMNs
occult blood
High rates of Salmonella in Africa suggests an association with _____.
HIV
The most common sites of focal Salmonella infection are _____.
skeletal system
meninges
intravascular sites
sites of preexisting abnormalities
_____ are not recommended for uncomplicated Salmonella gastroenteritis because suppression of normal gut flora can prolong infection and induce a chronic carrier state.
Antibiotics
S. typhimurium phage type DT104 is resistant to _____.
Ampicillin Chloramphenicaol Streptomycin Sulfonamides Tetracycline
Salmonella Gastroenteritis Treatment
Cefotaxime
Ceftriaxone
Ampicillin
Cefixime
Salmonella Gastroenteritis Treatment:
Cefotaxime Dose
100-200 mkday q6-8 x 5-14 days
Salmonella Gastroenteritis Treatment:
Ceftriaxone Dose
75 mkday OD x 7 days
Salmonella Gastroenteritis Treatment:
Ampicillin Dose
100 mkday q6-8 x 7 days
Salmonella Gastroenteritis Treatment:
Cefixime Dose
15 mkday x 7-10 days
Typhoid Fever is caused by _____ which is G (-).
Salmonella typhi
_____ is a virulence factor present in 90% of S. typhi and has a protective effect against the host’s immune system.
Polysaccharide Capsule Vi
_____ found in S. typhi interferes with phagocytosis by preventing the binding of C3 to the surface of the bacteria.
Polysaccharide Capsule Vi
Salmonella typhi is resistant to _____.
Ampicillin
Chloramphenicol
TMP-SMX
It takes _____ S. typhi to manifest clinical symptoms.
10^5 - 10^9
The incubation period of S. typhi is _____.
7-14 days
Primary S. typhi bacteremia results from _____.
lymphatic spread from intestinal mucosa and mesenteric LNs
Secondary S. typhi bacteremia occurs when bacteria are shed into the blood after a period of replication within the _____.
macrophages in the RES
Secondary S. typhi bacteremia coincides with _____.
onset of clinical symptoms
Typhoid Fever Pattern
stepladder rise (gradual rise)
S. typhi causes a macular or maculopapular rash called _____ may be visible around the 7-10th day of illness.
Rose Spots
Risk Factors for Typhoid Carrier Status
gallbladder disease
advanced age
antibiotic resistance of prevalent strains
S. typhi forms a biofilm in the _____ of a carrier.
gallbladder
The mainstay of the diagnosis of Typhoid Fever is _____.
(+) culture result
Typhoid Fever Culture Studies:
Blood
(+) early in the disease
Typhoid Fever Culture Studies
Stool
(+) after 1 week
Typhoid Fever Culture Studies\Urine
(+) after 1 week
The _____ measures antibodies against O and H antigens of S. typhi.
Widal Test
Typhoid Fever Treatment:
uncomplicated, fully sensitive
Chlorampphenicol 50-75 mkday x 14-21 days
Typhoid Fever Treatment:
uncomplicated, multidrug-resistant
Amoxicillin 75-100 mkday x 14 days
Fluorouinolone 15 mkday x 5-7 days
Cefixime 15-20 mkday x 7-14 days
Typhoid Fever Treatment:
uncomplicated, quinolone-resistant
Azithromycin 8-10 mkday x 7 days
Ceftriaxone 75 mkday x 10-14 days
Typhoid Fever Treatment:
uncomplicated, quinolone-resistant
Azithromycin 8-10 mkday x 7 days
Ceftriaxone 75 mkday x 10-14 days
Typhoid Fever Treatment:
severe, fully sensitive
Fluoroquinolone 15 mkday x 10-14 days
Typhoid Fever Treatment:
severe, multidrug-resistant
Fluoroquinolone 15 mkday x 10-14 days
Typhoid Fever Treatment:
severe, quinolone-resistant
Ceftriaxone 60 mkday x 10-14 days
Cefotaxime 80 mkday x 10-14 days
Individuals who excrete S. typhi for _____ after infection are considered chronic carriers
≥ 3 mos.
_____ is used to describe the syndrome of bloody diarrhea with fever, abdominal cramps, rectal pain and mucoid stools.
Dysentery
_____ causes bacillary dysentery.
Shigella
The basic virulence trait of Shigella is _____.
the ability to invade epithelial cells
_____ is a potent exotoxin in Shigella that inhibits protein synthesis.
Shiga Toxin
The Shiga Toxin is found in _____
S. dysenteria serotype 1
Shiga Toxin-ProducingE. Coli (STEC) → HUS
The target organ of Shigella is the _____.
colon
_____ are among the most common extraintestinal manifestations of bacillary dysentery.
Neurologic findings
The most common complication if shigellosis is _____.
dehydration
_____ is a rare syndrome caused by Shigella which manifests as severe toxicity, convulsions, extreme hyperpyrexia, and headache followed by brain edema.
Ekiri Syndrome
Lethal Toxic Encephalopathy
Presumptive data supporting the diagnosis if bacillary dysentery include _____.
fecal leukocytes
fecal blood
leukocytosis with left shift
_____ is the recommended drug for bacillary dysentery.
Ciprofloxacin 20-30 mkday BID
_____ supplementation may be given for children with bacillary dysentery.
Vit. A 200,000 IU as single dose - lessen severity
Zinc 20 mg x 14 days - decrease duration
_____ immunization can reduce the incidence and severity of diarrheal diseases including shigellosis.
Measles
_____ is a facultatively anaerobic G (-) bacilli that usuali ferments lactose.
Escherichia coli
E. coli Strains: > 1 y.o. and travelers watery +++ bloody - acute colonization factor (CF) E. coli common pilus (ECP heat-labile enterotoxin (LT) heat-stable enterotoxin (ST)
Enterotoxigenic E. coli (ETEC)
E. coli Strains:
“Traveler’s DIarrhea”
Enterotoxigenic E. coli (ETEC)
The LT in ETEC stimulates _____.
adenylate cyclase
The ST in ETEC stimulates _____.
guanylate cyclase
E. coli Strains: > 1 y.o. watery + bloody ++ acute invasion plasmid antigen (ipaABCD) (-) toxins
Enteroinvasive E. coli (EIEC)
E. coli Strains:
symptoms resemble bacillary dysentery because they share virulence genes with Shigella
Enteroinvasive E. coli (EIEC)
E. coli Strains: < 2 y.o. watery +++ bloody + acute, prolonged, persistent A/E lesion, intimin/Tir, EspABD, Bfp EspF, Map, EAST1, SPATEs (EspC)
Enteropathogenic E. coli (EPEC)
E. coli Strains:
major cause of acute and persistent diarrhea in children < 2 y.o. in developing countries
Enteropathogenic E. coli (EPEC)
E. coli Strains:
breastfeeding is protective against diarrhea
Enteropathogenic E. coli (EPEC)
E. coli Strains:
induces a characteristic attaching and effacing (A/E) histopathologic lesion
Enteropathogenic E. coli (EPEC)
E. coli Strains: 6 mos. - 10 y.o., elderly watery + bloody +++ acute A/E lesion, intimin/Tir, EspABD Shiga toxins (Stx1, Stx2)
Shiga Toxin Producing E.coli (STEC)
Enterohemorrhagic E. coli (EHEC)
Verotoxin Producing E. Coli (VTEC)
STEC differs from shigellosis or EIEC because _____ is uncommon.
fever
E. coli Strains:
5-10% develop complications like HUS
Shiga Toxin Producing E.coli (STEC)
Enterohemorrhagic E. coli (EHEC)
Verotoxin Producing E. Coli (VTEC)
_____ are the key virulence factors for EHEC/VTEC.
Shiga toxins
E. coli Strains: < 2 y.o., HIV, travelers watery +++ bloody + acute, prolonged, persistent aggregative adherence fimbriae (AAF) SPATEs (Pic,Pet), ShET1, EAST1
Enteroaggregative E. coli (EAEC)
E. coli Strains:
associated with acute and persistent diarrhea in children < 2 y.o. in developing countries as well as chronic diarrhea in HIV (+) individuals
Enteroaggregative E. coli (EAEC)
E. coli Strains:
forms a characteristic biofilm on the intestinal mucosa and induce shortening of the villi, hemorrhagic necrosis, and inflammatory responses
Enteroaggregative E. coli (EAEC)
E. coli Strains: > 1y.o., travelers watery ++ bloody - acute Afa/Dr, AIDA-I SPATES (Sat)
Diffusely Adherent E. coli (DAEC)
E. coli Strains:
produces acute watery diarrhea in children after the first 1-2 years that is not dysenteric and often prolonged
Diffusely Adherent E. coli (DAEC)
_____ is the most virulent STEC serotype and most frequently associated with HUS.
O157:H7
STEC O157:H7 is suggested by isolation of E. coli that fails to ferment _____ on _____.
sorbitol
MacConkey agar
The cornerstone of management of E. coli diarrhea is _____.
fluid and electrolyte therapy
EIEC infections can be treated with _____.
TMP-SMX
______ is a G (-) comma-shaped bacillus.
Vibrio cholerae
Vibrio cholerae is divided into serogroups by its _____.
somatic O antigen
Cholera epidemics are cause by _____.
V. cholerae O1 and O139
The most extensive cholera pandemic was caused by _____.
V. cholerae O1 El Tor
V. cholerae is transmitted through _____.
contaminated water and undercooked shellfish
Risk Factors for Severe Cholera
blood type O ↓gastric acidity malnutrition immunodeficiency ↓intestinal immunity
Large inocula of bacteria, _____ of organisms, is needed for severe cholera to occur.
> 10^8
The cholera toxin consists of _____ subunits.
5 binding B subunits
1 active A subunit
The _____ of the cholera toxin binds to the GM1 ganglioside receptors in the intestine.
B subunit
The _____ of the cholera toxin stimulates adenylate cyclase.
A subunit
The hallmark of _____ is painless purging of profuse rice-water stools (suspended flecks of mucus) with a fishy smell.
cholera
_____ is the most severe form of cholera where purging rates of 500-1000 ml/hour occur.
Cholera Gravis
_____ is the gold standard for diagnosing cholera.
Microbiologic isolation of V. cholerae
V. cholerae can be cultured on _____.
Thiosulfate Citrate Bile Salts Sucrose (TCBS) Agar
Dark-field microscopy may be used for rapid identification of typical _____ motility in wet mounts of rice-water stools.
darting
_____ is the mainstay therapy of cholera.
Rehydration.
_____ should be used during rehydraion for cholera.
Rice-based ORS
Antiobiotics in cholera are used to _____.
shorten duration of illness
decrease fecal excretion of vibrios
decrease volume of diarrhea
reduce the fluid requirement during rehydration
For cholera, single dose antibiotics such as _____ are recommended to increase compliance.
Doxycycline 2-4 mg/kg PO
Ciprofloxacin 20 mg/kg PO
Azithromycin 20 mg/kg PO
_____ are G (-), curved, thin, non-spore-forming rods that have tapered ends.
Campylobacter
Campylobacter are motile with a _____.
flagellum at 1 or both poles
_____ are microaerophilic, partially anaerobic, oxidase (+) and do not oxidize or ferment carbohydrates.
Campylobacter
Campylobacter differ from oterh enteric bacterial pathogens in that they have both _____.
N- and O-linked glycosylation capacities
_____ are a classic source of Campylobacter.
Chickens
C. jejuni has strong association with _____.
Guillain-Barre Syndrome
_____ infection should be considered when evaluating Inflammatory bowel disease.
Campylobacter
the most common presentation of Campylobacter is _____.
enteritis
Campylobacter is treated with _____ if necessary.
Erythromycin
Azithromycin
_____ is an acute demyelinating disease of the peripheral nervous system characterized by acute flaccid paralysis and is the most common cause of neuromuscular paralysis worldwide.
Guillain-Barre Syndrome
_____ is the most common Yersinia species causing human disease.
Yersinia enterocolitica
_____ causes fever, diarrhea and abdominal pain that can mimic appendicitis.
Yersinia
_____ causes acute febrile lymphadenitis seen in the bubonic plague.
Yersinia pestis
_____ is a large, G (-) coccobacillus that exhibit little or no bipolarity when stained with methylene blue and carbol fuchsin.
Yersinia enterocolitica
_____ ferments glucose and sucrose but not lactose, is an oxidase (-) facultative anaeerobe and reduces nitrate to nitrite.
Yersinia enterocolitica
Yersinia enterocolitica are motile at _____
22°C but not at 37°C
_____ are the major reservoir of Yersinia enterocolitica.
Pigs
Risk Factors for Yersinia enterocolitica Infection
iron overload
hemochromatosis
thalassemia
sickle cell disease
Yersinia enterocolitica has been associated with _____ disease.
Kawasaki
_____ is recommended as empirical treatment for Yersinia enterocolitica.
TMP-SMX
_____ is a G (-) facultative anaerobe that is a pleomorphic non-motile, non-spore-forming coccobacillus and is a potential agent for bioterrorism.
Yersinia pestis
The most common mode of transmission of Yersinia pestis is _____
flea bite (Xenopsylla cheopis)
3 Principal Clinical Presentations of Plague
Bubonic
Septicepmic
Pneumonic
Clinical Presentations of Plague:
most common form
Bubonic
In the bubonic plague, lymphadenitis (buboes) develop most commonly in the _____ area.
inguinal
In the Black Death, ______ of the extremities can develop as a result of intravascular coagulation.
purpura and gangrene
Clinical Presentations of Plague:
systemic infection without buboes
Septicemic
Clinical Presentations of Plague
least common but most dangerous and lethal form
Pneumonic
______ is the drug of choice for the bubonic plague.
Steptomycin 30 mkday q12 IM x 10 days
- max. 2 g/day
Postexposure prophylaxis using _____ should be given to those exposed to pneumonic plague.
Tetracycline
Doxycycline
TMP-SMX
*7 days
_____ is a strictly aerobic, oxidase (+), G (-) rod that does not ferment lactose and may produce β-hemolysis on blood agar.
Pseudomonas aeruginosa
_____ is capable of chronic persistence due to the formation of biofilms, organized communities of bacteria encased in an extracellular matrix that protects the organism from the host immune response and the effects of antibiotics.
Pseudomonas aeruginosa
_____ infection causes ecthyma gangrenosum which begins as pink macules and progress to hemorrhagic nodules and eventually to ulcers with ecchymotic and gangrenous centers with eschar formation surrounded by an intense red areola.
Pseudomonas aeruginosa
A frequent focus preceding Pseudomonas aeruginosa bacteremia in newborns is _____.
conjunctivitis
_____ of fluid or gram of tissue is evidence suggestive of Pseudomonas aeruginosa.
≥ 100,000 CFU/ml
Antibiotics for P. aeruginosa
Ceftaziidime 150-250 mkday q6-8 IV (max. 6 g/day)
Piperacillin-Tazobactam 300-450 mkday q6-8 IV (max. 12 g/day)
Cefepime
Ticarcillin-Clavulanate
± Gentamicin
_____ is an acute, spastic, paralytic illness (lockjaw) that is caused by the neurotoxin produced by _____.
Tetanus
Clostridium tetani
_____ is a motile, G (+), spore-forming obligate anaerobe whose spores produce a drumstick or tennis racket appearance.
Clostridium tetani
The tetanus toxin is also called _____.
tetanospasmin
_____ is the 2nd most poisonous substance known surpassed only by botulinum toxin.
Tetanospasmin
The most common form of tetanus is _____.
neonatal or umbilical
Tetanus occurs after spores germinate, multiply and produce tetanus toxin in the _____ of an infected injury site.
↓oxidation-reduction potential
Tetanus toxin binds at the _____.
neuromuscular junction
Tetanus toxin initiallly enters the _____ by endocytosis.
motor nerve
In the sciatic nerve, tetanus transport rate was found to be _____.
3.4 mm/hr
The tetanus toxin exits the motor neuron in the spinal cord and enters the adjacent spinal inhibitor interneurons where it prevents release of _____.
glycine
GABA
The incubation period of C. tetani is _____.
2-14 days
The presenting symptom of 50% of tentanus cases is _____.
trismus
_____ results from intractable spasms of facial and buccal muscles.
Risus Sardoniucus (sardonic smile)
When paralysis from tetanus extends to the abdominal, lumbar, hip and thigh muscles, the patient may assume a hyperextension of the body called _____.
opisthotonos
Fever is common in tetanus because of _____.
the menergy consumed by spastic muscles
Neonatal tetanus manifests within _____.
3-12 days from birth
_____ results in painful spasms of the muscles adjacent o the wound site.
Localized Tetanus
Tetanus toxin cannot be inhibited by TIG after it hasbegun its _____.
axonal ascent to the spinal cord
_____ is the antibiotic of choice for tetanus.
Penicillin G
The treatment of generalized tetanus requites _____.
muscle relaxants
neuromuscular blockade
Favorable Prognosis for Tetanus
long incubation period
absence of fever
localized disease
Poor Prognosis for Tetanus
trismus < 7 days after injury
generalized tetanic spasms < 3 days after trismus
Diphtheria Toxoid-Tetans Toxoid-Acellular Pertussis (DTaP) should be given at _____.
2-4-6 mos.
Diphtheria Toxoid-Tetans Toxoid-Acellular Pertussis (DTaP) booster should be given at _____.
4-6 y.o.
10 year intervals thereafter
