Infectious Diseases Flashcards
0
Q
Components/type of vaccine for Polio and Hepatitis A
a. whole inactivated microorganisms
b. parts of the organism
c. polysaccharide capsules
d. polysaccharide capsules conjugated to protein carriers
e. live-attenuated microorganisms
f. toxoids
A
A. whole inactivated microorganisms
1
Q
Components/type of vaccine for pneumococcal and meningococcal polysaccharide vaccine
a. whole inactivated microorganisms
b. parts of the organism
c. polysaccharide capsules
d. polysaccharide capsules conjugated to protein carriers
e. live-attenuated microorganisms
f. toxoid
A
C. polysaccharide capsules
2
Q
Components/type of vaccine for acellular pertussis, HPV, and Hep
a. whole inactivated microorganisms
b. parts of the organism
c. polysaccharide capsules
d. polysaccharide capsules conjugated to protein carriers
e. live-attenuated microorganisms
f. toxoid
A
B. parts of the organism
3
Q
Components/type of vaccine for measles, mumps, rubella, varicella, rotavirus, and live-attenuated influenza vaccines
a. whole inactivated microorganisms
b. parts of the organism
c. polysaccharide capsules
d. polysaccharide capsules conjugated to protein carriers
e. live-attenuated microorganisms
f. toxoid
A
e. live-attenuated microorganisms
4
Q
Components/type of vaccine for Hib, pneumococcal, and meningococcal conjugate vaccines
a. whole inactivated microorganisms
b. parts of the organism
c. polysaccharide capsules
d. polysaccharide capsules conjugated to protein carriers
e. live-attenuated microorganisms
f. toxoid
A
d. polysaccharide capsules conjugated to protein carrier
5
Q
Components/type of vaccine for tetanus and diphtheria
a. whole inactivated microorganisms
b. parts of the organism
c. polysaccharide capsules
d. polysaccharide capsules conjugated to protein carriers
e. live-attenuated microorganisms
f. toxoid
A
f. toxoid
6
Q
Mechanisms of fever production (3)
A
pyrogens (endogenous /exogenous )
heat production exceeding loss (salicylate poisoning or malignant hyperthermia)
defective heat loss (ectodermal dysplasia / severe heat exposure)
7
Q
Give examples of drugs known to cause fever (3)
A
allopurinol
vancomycin
amphotericin B
8
Q
In an infant 1-3 mos old with temperature >38C, with no localizing signs, unremarkable medical history, and normal PE, what laboratory studies should be done to ascertain that the patient may be managed as outpatient and no antibiotics are needed?
A
Lab Studies should be normal:
Urine: no leukocyte esterase or nitrite,WBC< 1500; or band:total neutrophil ratio <8, negative gram stain
CXR: no infiltrate
If child does not fulfill all low-risk criteria, hospitalize and administer parenteral antibiotics until all cultures are final and definitive diagnosis determined and treated.
9
Q
What are the four subtypes of FUO?
A
Classic FUO
Health-care associated
Immune-deficient
HIV related
10
Q
What is the definition of Fever of Unknown Origin in children?
A
- children with fever documented by a health care provider
2. cause could not be identified after 3 wk of evaluation as an outpatient or after 1 wk of evaluation in the hospital
11
Q
Define classic FUO
A
fever >38 C
> 3 weeks
> 2 visits or > 1 week in hospital
12
Q
Define healthcare associated FUO
A
fever > 38 C
> 1 week
Not present or incubating on admission
13
Q
Define neutropenia
A
ANC < 1000 cells/mm3
- associated with significant risk for developing severe bacterial and fungal disease
14
Q
Most often manifests during the 1st year of life with cellulitis, perirectal abscesses, or stomatitis from Staphylococcus aureus or Pseudomonas aeruginosa
A
Primary congenital neutropenia
neutropenia - absolute neutrophil count of <1,000 cells/mm3
15
Q
Fixed cycles of severe neutropenia between periods of normal granulocyte number. Most often the disease is characterized by recurrent aphthous ulcers and stomatitis during the periods of neutropenia
A
Cyclic neutropenia
- cycles classically occur every 21 days (range, 14-36 days), with neutropenia lasting 3-6 days
- most neutropenic syndromes respond to colony stimulating factor
16
Q
Children with this defect can have a history of delayed cord separation and recurrent infections of the skin, oral mucosa, and genital tract beginning early in life.
A
Leukocyte adhesion defects
- caused by defects in the β chain of integrin (CD18), which is required for the normal process of neutrophil aggregation and attachment to endothelial surface
- neutrophil count in the peripheral blood is usually extremely elevated and pus is not found at the site of infection
17
Q
Inherited neutrophil dysfunction syndrome where neutrophils have defects in their NADPH oxidase function, rendering them incapable of generating superoxide and thereby impairing intracellular killing
A
Chronic granulomatous disease
common pathogens:
S. aureus, Serratia marcescens, Burkholderia cepacia, Nocardia spp, Aspergillus
infections usually affect liver, bone, and lungs
prophylaxis:
trimethoprim-sulfamethoxazole, recombinant human interferon-γ (IFN-γ), and oral antifungal agents
18
Q
Children who have congenital asplenia or splenic dysfunction due to hemoglobinopathies such as sickle cell disease or have undergone splenectomy are at risk for serious infections from these pathogens (2)
A
encapsulated bacteria
blood-borne protozoa such as Plasmodium and Babesia
- consider prophylaxis with penicillin, esp in children under 5 yo
- most common causative organisms include Streptococcus pneumoniae, Haemophilus influenzae type b, and Salmonella, which can cause sepsis, pneumonia, meningitis, and osteomyelitis
19
Q
Terminal complement defects (C5, C6, C7, C8, and C9) are associated with recurrent infections with this pathogen
A
Neisseria
- Vaccines for S. pneumoniae, H. influenzae type b, and Neisseria meningitidis should be administered to all children with abnormalities in opsonization or complement pathways.
20
Q
Antibody deficiency that leads to a lack of production of secretory antibody at the mucosal membranes
A
Selective IgA deficiency
- recurrent sinopulmonary infection and GI disease are the major clinical manifestations
21
Q
Caused by a defect in the CD40 ligand on the T cell and is associated with a deficiency in the production of IgG and IgA antibody. Recurrent neutropenia, hemolytic anemia, or aplastic anemia can be present
A
Hyper-IgM Syndrome
- at risk for bacterial sinopulmonary infections, Pneumocystis jiroveci pneumonia (PCP), and Cryptosporidium intestinal infection
22
Q
The mainstay of treatment for most of the primary IgG antibody deficiencies
A
intravenous immunoglobulin (IVIG)
- not advocated for IgA deficiency, because it does not correct the defect
23
Q
X-linked recessive disease associated with eczema, thrombocytopenia, a reduced number of CD3 lymphocytes, moderately suppressed mitogen responses, and impaired antibody response to polysaccharide antigens
A
Wiskott-Aldrich syndrome
- infections with S. pneumoniae or H. influenzae type b and PCP are common
W- Weeping skin lesions- eczema
A- Absent platelets- thrombocytopenia - leading to petechiae
S- Severe immunodeficiency…… (low IgM and high IgA & IgE levels)
24
Children with this syndrome have markedly elevated levels of IgE and present with recurrent episodes of S. aureus abscesses of the skin, lungs, and musculoskeletal system
hyper IgE syndrome
25
Single most common finding among infants with congenital rubella syndrome
Nerve deafness
26
Most common ocular abnormality in congenital rubella syndrome
salt and pepper retinopathy
- unilateral or bilateral cataracts are the most serious ocular abnormality
27
The most common cause of viral meningitis in mumps-immunized populations, accounting for up to 90% or more of cases in which a cause is identified
Enteroviruses
28
1) Viral infection characterized by sudden onset of fever, sore throat, dysphagia, and lesions in the posterior pharynx.
2) Which virus is most commonly implicated?
Herpangina
Coxsackie A virus
29
1) Viral infection characterized by paroxysmal thoracic pain, due to myositis involving chest and abdominal wall muscles
2) Commonly implicated viral etiology
1) Pleurodynia (Bornholm disease)
| 2) Coxsackie B and Echovirus
30
What is the usual viral cause of acute hemorrhagic conjunctivitis?
enterovirus 70 and coxsackievirus
31
The second most common cause of orchitis, next to mumps
Enteroviruses
32
primary site of replication of poliovirus
M cells lining the mucosa of the small intestine
33
The most common cause of congenital infection, which occasionally causes the syndrome of cytomegalic inclusion disease (hepatosplenomegaly, jaundice, petechia, purpura, and microcephaly) in neonates
CMV
34
The best-known clinical syndrome caused by Epstein-Barr virus (EBV), characterized by systemic somatic complaints consisting primarily of fatigue, malaise, fever, sore throat, and generalized lymphadenopathy
Infectious mononucleosis
35
What is the classic triad of infectious mononucleosis?
fatigue
pharyngitis
generalized lymphadenopathy
36
The most valuable and specific serologic test for the diagnosis of acute EBV infection and is generally sufficient to confirm the diagnosis
detection of IgM antibody to VCA (viral capsid antigen)
37
What is the most feared complication of infectious mononucleosis?
subcapsular splenic hemorrhage or splenic rupture
- occurs most frequently in the second week
- a rare complication
38
WHO criteria for Dengue Hemorrhagic Fever except:
a. fever (2-7 days in duration or biphasic)
b. minor or major hemorrhagic manifestations
c. thrombocytopenia (≤100,000/mm3)
d. leukopenia
e. objective evidence of increased capillary permeability (hematocrit increased by ≥20%), pleural effusion or ascites (by chest radiography or ultrasonography), or hypoalbuminemia
d. leukopenia
39
WHO criteria for dengue shock syndrome
dengue hemorrhagic fever plus:
hypotension
tachycardia
narrow pulse pressure (≤20 mm Hg)
signs of poor perfusion (cold extremities)
40
Active TB disease caused by bacteria that are resistant to at least two of the most commonly used drugs for treatment (eg INF and RIF)
a. multi-drug resistant TB
b. extensively drug-resistant TB
A. multi-drug resistant TB
41
TB caused by MDR strains that are also resistant to a fluoroqunolone and to at least one second-line injectable agent (amikacin, kanamycin, and/or capreomycin)
a. multidrug resistant TB
b. extensively drug-resistant TB
B. extensively drug–resistant TB
42
Which immune response is the most important in the body's defense against TB?
a. antibodies and B lymphocytes
b. macrophages and T lymphocytes
c. PMNs and NK cells
d. all of the above
B. macrophages and T lymphocytes
- the primary defense against Tb
- antibodies and B lymphocytes have little role in protecting against TB
- role of PMNs and NK cells is unclear
43
Causative organism of diphtheria
Corynebacterium diphtheriae
44
What two other tissues usually remote from sites of C. diphtheriae infection can be significantly affected by diphtheritic toxin?
a. heart
b. lung
c. nervous system
A and C
Toxic cardiomyopathy occurs in 10-25% of patients with respiratory diphtheria and is responsible for 50-60% of deaths.
Characteristically occurs during the 2nd and 3rd weeks of illness as the pharyngeal disease improves but can appear acutely as early as the 1st wk of illness, a poor prognostic sign
Cranial neuropathies characteristically occur in the 5th wk, leading to oculomotor and ciliary paralysis, which can cause strabismus, blurred vision, or difficulty with accommodation.
Symmetric polyneuropathy has its onset 10 days to 3 mo after oropharyngeal infection and causes principally motor deficits with diminished deep tendon reflexes
45
What is the recommended prophylaxis for close contacts of a patient with suspected/confirmed diphtheria infection?
erythromycin (40-50 mg/kg/day divided qid PO for 10 days; maximum 2 g/day) or
single injection of benzathine penicillin G (600,000U IM for patients <30 kg, 1,200,000U IM for patients ≥30 kg)
46
What is the mainstay of therapy for diphtheria?
a. antimicrobial therapy
b. specific antitoxin
B. specific antitoxin
Equine diphtheria antitoxin is available in the USA only from the CDC
- neutralizes only free toxin, antitoxin efficacy diminishes with elapsed time after the onset of mucocutaneous symptoms
The role of antimicrobial therapy is to halt toxin production, treat localized infection, and prevent transmission of the organism to contacts. Antibiotic therapy is not a substitute for antitoxin therapy.
Only erythromycin or penicillin is recommended
47
A common presenting symptom of EBV infectious mononucleosis manifesting as perceptual distortions of sizes, shapes, and spatial relationships
Alice in Wonderland syndrome (metamorphopsia)
48
A vaccine preventable disease where neither natural disease nor vaccination provides complete or lifelong immunity against re-infection or disease.
A. Diphtheria
B. Tetanus
C. Pertussis
C. Pertussis
Protection against typical disease begins to wane 3-5 yr after vaccination and is unmeasurable after 12 yr
49
Which macrolide antibiotic is associated with increased risk of developing Infantile Hypertrophic Pyloric Stenosis (IHPS)?
a. azithromycin
b. clarithromycin
c. erythromycin
c. erythromycin
A 7- to 10-fold relative risk for infantile hypertrophic pyloric stenosis (IHPS) has been reported in neonates treated with orally administered erythromycin
53
What is the most common bacterial pathogen associated with community-acquired pneumonia in children 3 wk to 4 yr of age?
Streptococcus pneumoniae
Other bacterial causes of pneumonia in previously healthy children in the USA include group A streptococcus (Streptococcus pyogenes) and Staphylococcus aureus
54
What are the most frequent pathogens associated with community-acquired pneumonia in children 5 yrs and older?
Mycoplasma pneumoniae and
| Chlamydophila pneumoniae
55
The major causes of hospitalization and death from bacterial pneumonia among children in developing countries (3)
S. pneumoniae
H. influenzae
S. aureus
56
Common pathogens associated with pneumonia which must be considered in children with HIV
```
Mycobacterium tuberculosis
atypical mycobacteria
Salmonella
Escherichia coli
Pneumocystis jiroveci
```
57
Major viral pathogens associated with pneumonia in children <3 yrs of age
RSV
| influenza virus
58
Frequent pathogens of pneumonia in neonates (<3 wks)
```
Group B streptococcus
Escherichia coli
other gram-negative bacilli
Streptococcus pneumoniae
Haemophilus influenzae (type b,* nontypable)
```
*H. influenza type B is uncommon with routine HiB vaccination
59
Frequent pathogens of pneumonia in infants 3 wks - 3 mos old
Respiratory syncytial virus
other respiratory viruses (parainfluenza viruses, influenza viruses, adenovirus)
S. pneumoniae
H. influenzae (type b,* nontypable)
if patient is afebrile, consider Chlamydia trachomatis
60
Frequent pathogens of pneumonia in children 4 mos to 4 yrs old
```
Respiratory syncytial virus
other respiratory viruses (parainfluenza viruses, influenza viruses, adenovirus)
S. pneumoniae
H. influenzae (type b,* nontypable)
Mycoplasma pneumoniae
group A streptococcus
```
61
Frequent pathogens of pneumonia in children >5 yrs old
```
M. pneumoniae
S. pneumoniae
Chlamydophila pneumoniae
H. influenzae (type b,* nontypable)
influenza viruses
adenovirus
other respiratory viruses
Legionella pneumophila
```
62
In the pathogenesis of pneumonia, which etiologic agent produces local edema that aids in the proliferation of organisms and their spread into adjacent portions of lung, often resulting in the characteristic focal lobar involvement?
A. M. pneumoniae
B. S. pneumoniae
C. Group A Streptococcus
D. S. aureus
B. S. pneumoniae
local edema = lobar involvement
63
In the pathogenesis of pneumonia, which etiologic agent attaches to the respiratory epithelium, inhibits ciliary action, and leads to cellular destruction and an inflammatory response in the submucosa?
A. M. pneumoniae
B. S. pneumoniae
C. Group A Streptococcus
D. S. aureus
A. M. pneumoniae
As the infection progresses, sloughed cellular debris, inflammatory cells, and mucus cause airway obstruction, with spread of infection occurring along the bronchial tree, as it does in viral pneumonia.
64
In the pathogenesis of pneumonia, which etiologic agent causes infection of the lower respiratory tract, which results in more diffuse infection with interstitial pneumonia?
A. M. pneumoniae
B. S. pneumoniae
C. Group A Streptococcus
D. S. aureus
C. Group A Streptococcus
*The pathology includes necrosis of tracheobronchial mucosa; formation of large amounts of exudate, edema, and local hemorrhage, with extension into the interalveolar septa; and involvement of lymphatic vessels and the increased likelihood of pleural involvement.
65
In the pathogenesis of pneumonia, which etiologic agent manifests in confluent bronchopneumonia, often unilateral and characterized by the presence of extensive areas of hemorrhagic necrosis and irregular areas of cavitation of the lung parenchyma, resulting in pneumatoceles, empyema, or, at times, bronchopulmonary fistulas?
A. M. pneumoniae
B. S. pneumoniae
C. Group A Streptococcus
D. S. aureus
D. S. aureus
66
Define recurrent pneumonia
2 or more episodes in a single year or 3 or more episodes ever, with radiographic clearing between occurrences.
An underlying disorder should be considered if a child experiences recurrent pneumonia
67
The most consistent clinical manifestation of pneumonia
Tachypnea
68
FACTORS SUGGESTING NEED FOR HOSPITALIZATION OF CHILDREN WITH PNEUMONIA
Name at least 5
Age <6 mo
Sickle cell anemia with acute chest syndrome
Multiple lobe involvement
Immunocompromised state
Toxic appearance
Moderate to severe respiratory distress
Requirement for supplemental oxygen
Dehydration
Vomiting or inability to tolerate oral fluids or medications
No response to appropriate oral antibiotic therapy
Social factors (e.g., inability of caregivers to administer medications at home or follow up appropriately)
69
The most common causes of parapneumonic effusions and of empyema
(3 - SSS)
S. aureus, S. pneumoniae, and S. pyogenes
Table 392-6 -- DIFFERENTIATION OF PLEURAL FLUID
TRANSUDATE EMPYEMA
Appearance Clear Cloudy or purulent
Cell count (per mm3) 50,000
Cell type Lympho, mono PMNs (neutrophils)
Lactate dehydrogenase 1000 U/L
Pleural fluid/serum LDH ratio 0.6
Protein >3g Unusual Common
Pleural fluid/serum protein ratio 0.5
Glucose* Normal Low (<7.10
Gram stain Negative Occasionally positive
70
Which type of Salmonella predominantly manifests as systemic illness with a longer incubation period and duration of illness?
a. Salmonella serovars
b. non-typhoidal Salmonella (NTS)
a. Salmonella serovars
Once across the epithelium, Salmonella serotypes that are associated with systemic illness enter intestinal macrophages and disseminate throughout the reticuloendothelial system. Only a small proportion of children get diarrhea
71
Which type of Salmonella predominantly causes intestinal inflammation and diarrhea?
a. Salmonella serovars
b. non-typhoidal Salmonella (NTS)
b. non-typhoidal Salmonella (NTS)
non-typhoidal Salmonella (NTS) serovars induce an early local inflammatory response, which results in the infiltration of polymorphonuclear leukocytes into the intestinal lumen and diarrhea. The NTS serovars cause a gastroenteritis of rapid onset and brief duration.
72
The 2 most important serotypes for salmonellosis transmitted from animals to humans
Salmonella Enteritidis
| Salmonella Typhimurium
73
What is the optimal therapy for uncomplicated typhoid fever in the following settings of susceptibility:
1. Fully sensitive
2. Multi-drug resistant
3. Qunolone-resistant
1. Fully sensitive: chloramphenicol / amoxicillin
2. Multi-drug resistant: fluoroquinolone / cefixime
3. Quinolone resistant: azithromycin / ceftriaxone
```
Length of treatment
chloramphenicol - 14-21 days
amoxicillin - 14 days
fluoroquinolone - 5-7 days
azithromycin - 7 days
ceftriaxone - 10-14 days
```
74
What is the optimal therapy for severe typhoid fever in the following settings of susceptibility:
1. Fully sensitive
2. Multi-drug resistant
3. Quinolone-resistant
1. Fully sensitive: ampicillin / ceftriaxone
2. Multi-drug resistant: fluoroquinolone
3. Quinolone-resistant: ceftriaxone
Length of treatment
ampicillin - 14 days
ceftriaxone - 10-14 days
fluoroqunolone - 10-14 days
75
Where is the primary site of colonization of Salmonella typhi in the human host?
terminal ileum of the gut
After ingestion, S. Typhi organisms are thought to invade the body through the gut mucosa in the terminal ileum, possibly through specialized antigen-sampling cells known as M cells that overlie gut-associated lymphoid tissues, through enterocytes, or via a paracellular route
76
Rare complication of pelvic inflammatory disease caused by N. gonorheae which causes dissemination of infection from the fallopian tubes through the peritoneum to the liver capsule
perihepatitis (Fitz-Hugh–Curtis syndrome)
77
In uncomplicated gonorrhea, where is the primary site of infection in the following groups:
1. males
2. prepubertal females
3. postpubertal females
1. males - urethra
2. prepubertal females - vulva and vagina
3. postpubertal females - cervix
- Prepubertal girls are susceptible to vulvovaginitis; N. gonorrhoeae infects noncornified epithelium, and the thin noncornified vaginal epithelium and alkaline pH of the vaginal mucin predispose this age group to infection of the lower genital tract.
- Postpubertal females are more susceptible to salpingitis, especially during menses, when diminished bactericidal activity of the cervical mucus and reflux of blood from the uterine cavity into the fallopian tubes facilitate passage of gonococci into the upper reproductive tract
78
The most common initial symptom of disseminated gonococcal infection
acute onset of polyarthralgia with fever
79
What are the two clinical syndromes of disseminated gonococcal disease?
1. tenosenovitis-dermatitis syndrome
2. suppurative arthritis syndrome
The 1st and more common is the tenosynovitis-dermatitis syndrome, which is characterized by fever, chills, skin lesions, and polyarthralgia predominantly involving the wrists, hands, and fingers.
2nd syndrome is the suppurative arthritis syndrome, in which systemic symptoms and signs are less prominent and monarticular arthritis, often involving the knee, is more common
80
What is the recommended initial therapy for N. gonorrhoeae?
ceftriaxone combined with doxycycline or azithromycin (to target possible co-infection with Chlamydia)
Because of the prevalence of penicillin-resistant N. gonorrhoeae, ceftriaxone (a 3rd-generation cephalosporin) is recommended as initial therapy for all ages
A single dose of ceftriaxone (125 mg intramuscularly [IM]) eradicates pharyngeal and uncomplicated urogenital gonococcal infections. Ceftriaxone is safe and effective in pregnant women and probably aborts incubating syphilis. Alternative regimens include cefixime (400 mg by mouth [PO]) in a single dose
Regardless of the regimen chosen, treatment should be followed by a regimen active against C. trachomatis unless Chlamydia infection is ruled out by a negative chlamydial NAAT result. The recommended regimen is doxycycline (100 mg PO twice daily for 7 days) or azithromycin (1g PO in a single dose).
81
For infants with disseminated gonoccocal infection and concurrent hyperbilirubinemia, what is the drug of choice for treament?
cefotaxime
- because ceftriaxone competes for bilirubin binding sites on albumin
82
The severity of meningococcal disease is related to the circulating level of endotoxin in the bloodstream, which is also known as?
lipo-oligosaccharide (LOS)
The lipid A portion of meningococcal LOS is responsible for the toxicity of the molecule, sensed by host cells through Toll-like receptors (TLRs) -- leads to production of proinflammatory cytokines -- pathways of coagulation are activated -- capillary leak -- DIC -- MODS -- death
** Diffuse vasculitis and DIC are common with meningococcemia
83
This syndrome of diffuse adrenal hemorrhage without vasculitis is common during fulminant meningococcemia
Waterhouse-Friderichsen syndrome
84
Carriage of which antigenically related species elicit naturally acquired serum antibodies to meninggococci?
Neisseria lactamica
85
What is the antibiotic prophylaxis recommended for close contacts of patients with Neisseria meningitidis infection (meningococcemia)?
Rifampin
Ceftriaxone
Ciprofloxacin (for persons >18 yo)
86
At what age is meningococcal vaccination recommended in the general population (excluding at risk groups)?
Routine meningococcal vaccination is recommended for all children beginning at age 11 yr
A single dose of MCV4 or MenACWY-CRM at age 11-12 yr (at preadolescent assessment visit) or at high school entry (at approximately age 15 yr). A booster dose 5 yr later. Meningococcal vaccination is not recommended for persons 20-55 yrs old.
87
For high risk groups (eg anatomic or functional asplenia, complement component deficiency, children with HIV), what is the recommended vaccination schedule for meningococcemia?
For high risk groups:
children 9 mos and above - 2 doses, 2 mos apart (MCV4)
if person remains at increased risk - give MCV4 3 yrs after primary series then 5yr intervals after initial booster dose
88
Organism that causes bacillary dysentery which manifests as acute invasive enteric infection clinically manifested by diarrhea that is often bloody
Shigella
* Bacillary dysentery is a term often used to distinguish dysentery caused by Shigella from amoebic dysentery caused by Entamoeba histolytica
89
What is the potent exotoxin produced in significant amounts by Shigella dysenteriae serotype 1, which mediates the severe complication of hemolytic-uremic syndrome (HUS)?
Shiga toxin
- inhibits protein synthesis
- syndrome is caused by Shiga toxin–mediated vascular endothelial injury. E. coli that produce Shiga toxins also cause HUS
90
What is the target organ for Shigella?
the colon
- pathologic changes of shigellosis take place primarily in the colon, the target organ for Shigella. The changes are most intense in the distal colon, although pancolitis can occur. Shigellae cross the colonic epithelium through M cells in the follicle-associated epithelium overlying the Peyer patches
91
What is the most common extraintestinal manifestation of bacillary dysentery (specifically caused by Shigella)?
Neurologic manifestations
- occurring in as many as 40% of hospitalized children
- Enteroinvasive E. coli can cause similar neurologic toxicity.
- Convulsions, headache, lethargy, confusion, nuchal rigidity, or hallucinations may be present before or after the onset of diarrhea
92
What is the most common complication of shigellosis?
Dehydration
- Inappropriate secretion of antidiuretic hormone with profound hyponatremia can complicate dysentery, particularly when S. dysenteriae is the etiologic agent
93
A rare complication of shigellosis described as a syndrome of severe toxicity, convulsions, extreme hyperpyrexia, and headache followed by brain edema and a rapidly fatal outcome without sepsis or significant dehydration
Ekiri Syndrome or "lethal toxic encephalopathy"
94
What is the drug of choice recommended by WHO as treatment for all patients with bloody diarrhea, irrespective of age?
ciprofloxacin
- 30 mg/kg/24 hr divided into 2 doses for 5 days
- some experts recommend that these agents be reserved for seriously ill children with bacillary dysentery due to an organism that is suspected or known to be resistant to other agents, because overuse of quinolones promotes development of resistance to these drugs
- alternative drugs for shigellosis: azithromycin, cefixime, (ampicillin or tmp-smx for thise susceptable)
95
Among the diarrheagenic strains of E. coli, which type manifests as bloody diarrhea?
enteroinvasive E. coli (EIEC) and
| Shiga toxin–producing E. coli (STEC)
96
Among the diarrheagenic strains of E. coli, which type manifests as profuse watery non-bloody diarrhea?
enterotoxigenic E. coli (ETEC)
enteropathogenic E. coli (EPEC)
enteroinvasive E. coli (EIEC)
97
Which type of diarrheagenic E. coli primarily affects infants below 6 mos old?
enteropathogenic E. coli (EPEC)
- a major cause of acute and persistent diarrhea
- common symptoms: Profuse watery, nonbloody diarrhea with mucus, vomiting, and low-grade fever
98
Which diarrheagenic strain of E. coli uncommonly presents with fever?
shiga-toxin producing E. coli (STEC)
99
What are the stages of syphilis?
Primary syphilis - painless chancre + regional lymphadenitis
Secondary syphilis - spirochetemia, generalized maculopapular rash, condyloma lata (gray-white to erythematous wartlike plaques)
Latent period: Early latency / Late latency
Tertiary syphilis: marked by neurologic, cardiovascular, and gummatous lesions
(think PARESIS)
P ersonality
A ffect
R eflexes (eg, hyperactive)
E ye (eg, Argyll Robertson pupils)
S ensorium (eg, illusions, delusions, hallucinations)
I ntellect (eg, decreased recent memory, orientation, judgment, insight)
S peech abnormalities
* early latency - 1st yr of latent period, relapses may occur
* late latency - symptomatic period, may convert to tertiary syphilis
100
Late manifestation of congenital syphilis:
Bony prominence of the forehead due to persistent or recurrent periostitis
Olympian brow
101
Late manifestation of congenital syphilis:
Unilateral or bilateral thickening of the sternoclavicular third of the clavicle
Clavicular or Higouménaki sign
102
Late manifestation of congenital syphilis:
Anterior bowing of the midportion of the tibia
Saber shins
103
Late manifestation of congenital syphilis:
Convexity along the medial border of the scapula
Scaphoid scapula
104
Late manifestation of congenital syphilis:
Peg-shaped upper central incisors; they erupt during 6th yr of life with abnormal enamel, resulting in a notch along the biting surface
Hutchinson teeth
105
Late manifestation of congenital syphilis:
Abnormal 1st lower (6 yr) molars characterized by small biting surface and excessive number of cusps
Mulberry molars
106
Late manifestation of congenital syphilis:
Depression of the nasal root, a result of syphilitic rhinitis destroying adjacent bone and cartilage
Saddle nose
107
Late manifestation of congenital syphilis:
Linear scars that extend in a spoke-like pattern from previous mucocutaneous fissures of the mouth, anus, and genitalia
Rhagades
108
Late manifestation of congenital syphilis:
Latent meningovascular infection; it is rare and typically occurs during adolescence with behavioral changes, focal seizures, or loss of intellectual function
Juvenile paresis
109
Late manifestation of congenital syphilis:
Rare spinal cord involvement and cardiovascular involvement with aortitis
Juvenile tabes
110
Late manifestation of congenital syphilis:
Hutchinson teeth, interstitial keratitis, and 8th nerve deafness
Hutchinson triad
111
Late manifestation of congenital syphilis:
Unilateral or bilateral painless joint swelling (usually involving knees) due to synovitis with sterile synovial fluid; spontaneous remission usually occurs after several wk
Clutton joint
112
Late manifestation of congenital syphilis:
Manifests with intense photophobia and lacrimation, followed within weeks or months by corneal opacification and complete blindness.
Interstitial keratitis
113
Late manifestation of congenital syphilis:
May be unilateral or bilateral, appears at any age, manifests initially as vertigo and high-tone hearing loss, and progresses to permanent deafness
Eighth nerve deafness
114
Roentgenographic abnormality commonly seen in neonatal syphilis described as metaphyseal demineralization of the medial aspect of the proximal tibia
Wimberger's lines
- Bone involvement is common in congenital syphilis
- other bony involvement: multiple sites of osteochondritis at the wrists, elbows, ankles, and knees, and periostitis of the long bones
115
Osteochondritis in neonatal syphilis is painful and frequently leads to irritability and refusal to move the involved extremity, which is commonly referred to as?
pseudoparalysis of Parrot
116
What is the principal means for diagnosis of syphilis?
Serologic testing: nontreponemal test followed by confirmatory treponemal test
- non-treponemal tests: VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) -- quantitative results of these tests are helpful in screening and in monitoring therapy
> In congenital infection, these tests become nonreactive within a few months after adequate treatment
- Treponemal tests traditionally are used to confirm diagnosis and measure specific T. pallidum antibody: dark-field microscopy or direct fluorescent antibody testing
117
What is the drug of choice in the treatment of syphilis?
Penicillin
- Parenteral penicillin G is the only documented effective treatment for congenital syphilis, syphilis during pregnancy, and neurosyphilis.
- Aqueous crystalline penicillin G is preferred
- Although nonpenicillin regimens are available to the penicillin-allergic patient, desensitization followed by standard penicillin therapy is the most reliable strategy
118
What is the initial antibiotic therapy recommended for possible invasive H. influenzae infection!
Ceftriaxone
- initial antibiotic therapy of invasive infections possibly due to H. influenzae should be a parenterally administered antimicrobial agent effective in sterilizing all foci of infection and effective against ampicillin-resistant strains, usually an extended-spectrum cephalosporin such as cefotaxime or ceftriaxone
- drug of choice is AMPICILLIN for susceptible isolates
119
For the out-patient treament of H. influenzae infection, either as completion of parenteral therapy or treatment of non-invasive infectin (otitis media or sinusitis), what is the drug of choice?
Amoxicillin (if organism is susceptible)
Oral 3rd-generation cephalosporin (e.g., cefixime, cefdinir) or amoxicillin-clavulanate may be used when the isolate is resistant to ampicillin
120
What are the three most common bacterial pathogens causing otitis media?
H. influenzae
S. pneumoniae
Moraxella catarrhalis
- Amoxicillin (80-90 mg/kg/day) is a suitable first-line oral antimicrobial agent, because the probability that the causative isolate is resistant to amoxicillin and the risk for invasive potential are sufficiently low to justify this approach
- amoxicillin-clavulanate (Augmentin) and erythromycin-sulfisoxazole (Pediazole) are among the available alternatives
121
What are the common manifestations of HiB infection?
meningitis
otitis media
sinusitis
- may also present as soft tissue infection, such as cellulitis, usualy with an antecedent respiratory tract infection
122
What is the recommended prophylaxis for HiB exposure?
rifampin
- indicated for all members of the household or close contact group, including the index patient, if the group includes ≥1 child 1 mo of age, 20 mg/kg/dose, not to exceed 600 mg/dose) once a day for 4 consecutive days. The adult dose is 600mg once daily
123
The 2 most common forms of disease caused by E. histolytica
Amebic colitis
| Amebic liver abscess
124
Drug of choice for treatment of invasive amebiasis
Metronidazole or tinidazole
- tinidazole is similar in efficacy to metro, simpler regimen (once daily dosing) for only 3 days, but not locally available ;(
- metronidazole 35-50 mg/kg/day TID for 7-10 days
125
What is the mainstay of therapy for systemic candidiasis?
amphotericin B
- Nephrotoxicity, hypokalemia, and hypomagnesemia are common, but amphotericin B deoxycholate is better tolerated in neonates than in adult patients
- Fluconazole is very useful for treatment of invasive neonatal Candida infections, especially urinary tract infections
126
Fluconazole is not effective against which strains of Candida?
C. krusei and C. glabrata
127
Preceding infection with Campylobacter jejuni is strongly associated with what neurologic syndrome?
Guillan-Barre Syndrome
- There is a strong association between Guillain-Barre syndrome and preceding infection with some serotypes of C. jejuni.
- Molecular mimicry between nerve tissue and Campylobacter surface antigens may be the triggering factor in Campylobacter-associated Guillain-Barre syndrome
128
Parvovirus is otherwise known as
5th disease or erythema infectiosum
