A-IPC Exam Study Guide (Practice Test #1) Updated
Questions With Correct Solutions + Rationale
1. The Bacterium Most Likely To Be Transmitted From Mother To Infant During Labor
And Cause Neonatal Sepsis Is:
A. Escherichia Coli
B. Staphylococcus Aureus
C. Group B Streptococcus
D. Group A Streptococcus
ANS: C
Rationale: In Group B Streptococcus (GBS) Neonatal Infections, Heavy Maternal
Colonization Is Associated With An Increased Risk For Preterm Labor, Which In Turn Is
A Significant Risk Actor For Neonatal Infection. Intrauterine Infection Of The Fetus
Therefore Likely Occurs Via Ascending Spread Of GBS From The Vagina Of A
Pregnant, Asymptomatically Colonized Woman And Subsequent Rupture Of Membranes
Before 37 Weeks' Gestation.
2. Which Of The Following Is An Example Of The Criterion Of "Strength Of The
Association" From Hill's Criteria For Causation?
A. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, The Odds Ratio Was 2:3
B. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, The Authors' Conclusions Are Consistent With Those Of Three Other
Studies
C. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, Antibiotic Therapy Began An Average Of 3 Weeks Before C. Difficil
Infection Developed
,D. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, Prolonged Antibiotic Therapy Was A Greater Risk Factor For C.
Difficil Infection Than Short-Term Antibiotic Therapy
ANS: A.
Rationale: Causal Associations Exist When Evidence Indicates That One Factor Is
Clearly Shown To Increase The Probability Of The Occurrence Of A Disease. In A
Causal Relationship, The Reduction Or Diminution Of A Factor Decreases The
Frequency Of The Disease Being Studied. The Criteria Currently Used For Causality
Were Developed By Austin Bradford Hill And Are Known As Hill's Criteria. These
Criteria Use Modern Epidemiological Methods To Determine Whether A Factor Is
Causal For A Given Disease. Strength Of Association Is The Firt Criterion: The
Incidence Of Disease Should Be Higher In Those Who Are Exposed To The Factor
Under Consideration Than In Those Who Are Not Exposed; That Is, The Stronger The
Association Between An Exposure And A Disease, The More Likely The Exposure Is To
Be Causal. The Odds Ratio Is A Statistical Measure That Gives Us An Indication Of
How Strongly The Risk Factor Is Associated With The Disease Outcome.
3. Which Of The Following Rules Should Be Followed When Collecting A Stool Sample
For C. Difficil Testing?
1) Stool Sample Should Be Freshly Passed Within 1-2 Hours
2) 10-20ml. Of Formed Stool Should Be Collected
3) Stool Should Be Passed Into A Clean, Dry Container
4) Specimens Should Be Obtained Before Antimicrobial Agents Have Been
Administered
A. 1, 2
B. 2, 3
C. 1, 3
D. 1, 4
ANS: C.
,Rationale: The Accuracy Of All Tests Depends On Proper Specimen Handling And
Transport. The Following Rules Should Be Followed When Collecting Samples For C.
Difficil Testing:• Stool Samples Should Be Freshly Passed Within 1-2 Hours• 10-20 Ml
Of Watery, Soft, Or Unformed Stool Should Be Collected• Stool Should Be Passed Into
A Clean, Dry Container
4. What Type Of Meningitis Would Be Most Consistent With The Following
Cerebrospinal Fluid CSF) Report Result:
Glucose Decreased
Protein Elevated
WBC Counts1,000/Mm3
A. Bacterial
B. Viral
C. Fungal
D. Tuberculosis
ANS: A.
Rationale: Culture Of Blood And CSF Are Indicated For Patients With Suspected
Invasive Meningococcal Disease. The CSF Of Patients With Untreated Meningococcal
Meningitis Is Usually Cloudy And Has Pleocytosis With A Predominance Of
Neutrophils, Low Glucose, And High Protein Levels. In Most Of The Cases, The
Organisms Are Seen On Gram Stain Or Can Be Identified Usinglatex Agglutination
Assays. The Culture Is Almost Invariably Positive As Long As The Sample Was
Obtained Before The Administration Of Antibiotics.
5. The Following Blood Culture Result Should Be Considered A Potential Contaminant:
A. A Positive Result Of Coagulase-Negative Staphylococci From Two Sets, 2 Days
Apart, Without Symptoms
B. A Positive Result Of S. Aureus From One Bottle In A Patient With A Temperature Of
38.6°C
C. A Positive Result Of E. Coli From One Bottle In An Afebrile Patient With Diarrhea
, D. A Positive Result Of Candida Albicans In A Fungal Blood Culture In A Patient With
A Urinary Tract Infection
ANS: A.
Rationale: According To The CDC CLABSI Criteria, Common Commensals (Such As
Coagulase-Negative Staphylococci) Meet The Criteria For A CLABSI If There Are Two
Positive Cultures From Two Or More Sets Of Blood Cultures Drawn Less Than 2 Days
Apart And The Patient Has Symptoms (Fever Greater Than 38°C, Chills, Or
Hypotension). CDC CLABSI Criteria: Patient Has At Least One Of The Following Signs
Or Symptoms: Fever (Greater Than 38°C), Chills, Or Hypotension And Positive
Laboratory Results Are Not Related To An Infection At Another Site. And The Same
Common Commensal (I.E., Diphtheroids [Corynebacterium Spp. Not C. Diphtheriae],
Bacillus Spp. [Not B. Anthracis], Propionibacterium Spp., Coagulase-Negative
Staphylococci [Including S. Epidermidis], Viridans Group Streptococci, Aerococcus
Spp., And Micrococcus Spp.) Is Cultured From Two Or More Blood Cultures Drawn On
Separate Occasions.Criterion Elements Must Occur Within A Time Frame That Does Not
Exceed A Gap Of 1 Calendar Day Between Two Adjacent Elements.
6. Which Of The Following Organisms Have Been Associated With The Transmission
Of Infections After Body Piercing?
1) Atypical Mycobacterium Species
2) Staphylococcus Species
3) Pseudomonas Species
4) Haemophilus Species
A. 1, 2, 3
B. 2, 3, 4
C. 1, 3, 4
D. 1, 2, 4
ANS: A.
Questions With Correct Solutions + Rationale
1. The Bacterium Most Likely To Be Transmitted From Mother To Infant During Labor
And Cause Neonatal Sepsis Is:
A. Escherichia Coli
B. Staphylococcus Aureus
C. Group B Streptococcus
D. Group A Streptococcus
ANS: C
Rationale: In Group B Streptococcus (GBS) Neonatal Infections, Heavy Maternal
Colonization Is Associated With An Increased Risk For Preterm Labor, Which In Turn Is
A Significant Risk Actor For Neonatal Infection. Intrauterine Infection Of The Fetus
Therefore Likely Occurs Via Ascending Spread Of GBS From The Vagina Of A
Pregnant, Asymptomatically Colonized Woman And Subsequent Rupture Of Membranes
Before 37 Weeks' Gestation.
2. Which Of The Following Is An Example Of The Criterion Of "Strength Of The
Association" From Hill's Criteria For Causation?
A. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, The Odds Ratio Was 2:3
B. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, The Authors' Conclusions Are Consistent With Those Of Three Other
Studies
C. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, Antibiotic Therapy Began An Average Of 3 Weeks Before C. Difficil
Infection Developed
,D. In A Study Of The Association Between Antibiotic Exposure And Development Of C.
Difficil Infection, Prolonged Antibiotic Therapy Was A Greater Risk Factor For C.
Difficil Infection Than Short-Term Antibiotic Therapy
ANS: A.
Rationale: Causal Associations Exist When Evidence Indicates That One Factor Is
Clearly Shown To Increase The Probability Of The Occurrence Of A Disease. In A
Causal Relationship, The Reduction Or Diminution Of A Factor Decreases The
Frequency Of The Disease Being Studied. The Criteria Currently Used For Causality
Were Developed By Austin Bradford Hill And Are Known As Hill's Criteria. These
Criteria Use Modern Epidemiological Methods To Determine Whether A Factor Is
Causal For A Given Disease. Strength Of Association Is The Firt Criterion: The
Incidence Of Disease Should Be Higher In Those Who Are Exposed To The Factor
Under Consideration Than In Those Who Are Not Exposed; That Is, The Stronger The
Association Between An Exposure And A Disease, The More Likely The Exposure Is To
Be Causal. The Odds Ratio Is A Statistical Measure That Gives Us An Indication Of
How Strongly The Risk Factor Is Associated With The Disease Outcome.
3. Which Of The Following Rules Should Be Followed When Collecting A Stool Sample
For C. Difficil Testing?
1) Stool Sample Should Be Freshly Passed Within 1-2 Hours
2) 10-20ml. Of Formed Stool Should Be Collected
3) Stool Should Be Passed Into A Clean, Dry Container
4) Specimens Should Be Obtained Before Antimicrobial Agents Have Been
Administered
A. 1, 2
B. 2, 3
C. 1, 3
D. 1, 4
ANS: C.
,Rationale: The Accuracy Of All Tests Depends On Proper Specimen Handling And
Transport. The Following Rules Should Be Followed When Collecting Samples For C.
Difficil Testing:• Stool Samples Should Be Freshly Passed Within 1-2 Hours• 10-20 Ml
Of Watery, Soft, Or Unformed Stool Should Be Collected• Stool Should Be Passed Into
A Clean, Dry Container
4. What Type Of Meningitis Would Be Most Consistent With The Following
Cerebrospinal Fluid CSF) Report Result:
Glucose Decreased
Protein Elevated
WBC Counts1,000/Mm3
A. Bacterial
B. Viral
C. Fungal
D. Tuberculosis
ANS: A.
Rationale: Culture Of Blood And CSF Are Indicated For Patients With Suspected
Invasive Meningococcal Disease. The CSF Of Patients With Untreated Meningococcal
Meningitis Is Usually Cloudy And Has Pleocytosis With A Predominance Of
Neutrophils, Low Glucose, And High Protein Levels. In Most Of The Cases, The
Organisms Are Seen On Gram Stain Or Can Be Identified Usinglatex Agglutination
Assays. The Culture Is Almost Invariably Positive As Long As The Sample Was
Obtained Before The Administration Of Antibiotics.
5. The Following Blood Culture Result Should Be Considered A Potential Contaminant:
A. A Positive Result Of Coagulase-Negative Staphylococci From Two Sets, 2 Days
Apart, Without Symptoms
B. A Positive Result Of S. Aureus From One Bottle In A Patient With A Temperature Of
38.6°C
C. A Positive Result Of E. Coli From One Bottle In An Afebrile Patient With Diarrhea
, D. A Positive Result Of Candida Albicans In A Fungal Blood Culture In A Patient With
A Urinary Tract Infection
ANS: A.
Rationale: According To The CDC CLABSI Criteria, Common Commensals (Such As
Coagulase-Negative Staphylococci) Meet The Criteria For A CLABSI If There Are Two
Positive Cultures From Two Or More Sets Of Blood Cultures Drawn Less Than 2 Days
Apart And The Patient Has Symptoms (Fever Greater Than 38°C, Chills, Or
Hypotension). CDC CLABSI Criteria: Patient Has At Least One Of The Following Signs
Or Symptoms: Fever (Greater Than 38°C), Chills, Or Hypotension And Positive
Laboratory Results Are Not Related To An Infection At Another Site. And The Same
Common Commensal (I.E., Diphtheroids [Corynebacterium Spp. Not C. Diphtheriae],
Bacillus Spp. [Not B. Anthracis], Propionibacterium Spp., Coagulase-Negative
Staphylococci [Including S. Epidermidis], Viridans Group Streptococci, Aerococcus
Spp., And Micrococcus Spp.) Is Cultured From Two Or More Blood Cultures Drawn On
Separate Occasions.Criterion Elements Must Occur Within A Time Frame That Does Not
Exceed A Gap Of 1 Calendar Day Between Two Adjacent Elements.
6. Which Of The Following Organisms Have Been Associated With The Transmission
Of Infections After Body Piercing?
1) Atypical Mycobacterium Species
2) Staphylococcus Species
3) Pseudomonas Species
4) Haemophilus Species
A. 1, 2, 3
B. 2, 3, 4
C. 1, 3, 4
D. 1, 2, 4
ANS: A.
