CIC: Practice Exam 1

CIC: Practice Exam 1 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 - Group B Streptococcus 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 factor 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. Reference: APIC Text, 4th edition, Chapter 94 - Streptococci 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. difficile infection, the odds ratio was 2:3 b. In a study of the association between antibiotic exposure and development of C. difficile 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. difficile infection, antibiotic therapy began an average of 3 weeks before C. difficile infection developed d. In a study of the association between antibiotic exposure and development of C. difficile infection, prolonged antibiotic therapy was a greater risk factor for C. difficile infection than short-term antibiotic therapy - In a study of the association between antibiotic exposure and development of C. difficile infection, the odds ratio was 2:3 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 first 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. Reference: APIC Text, 4th edition, Chapter 10 3. Which of the following rules should be followed when collecting a stool sample for C. difficile testing? 1) Stool sample should be freshly passed within 1-2 hours 2) 10-20rnL. 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 - 1, 3 1) Stool sample should be freshly passed within 1-2 hours 3) Stool should be passed into a clean, dry container Rationale: The accuracy of all tests depends on proper specimen handling and transport. The following rules should be followed when collecting samples for C. difficile 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 Reference: APIC Text, 4th edition, Chapter 72 4. What type of meningitis would be most consistent with the following cerebrospinal fluid (CSF) report result: +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Glucose: decreased Protein: elevated WBC: 1,000/mm(3) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ a. Bacterial b. Viral c. Fungal d. Tuberculosis - Bacterial 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 pleocytosis (WBC in CSF) with a predominance of neutrophils, low glucose, high protein levels In most of the cases, the organisms are seen on Gram stain or can be identified using latex agglutination assays. The culture is almost invariably positive as long as the samples was obtained before the administration of antibiotics. Reference: APIC Text, 4th edition, Chapter 74 - Central Nervous System Infection 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 - A positive result of coagulase negative staphylococci from two sets, 2 days apart without symptoms 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 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.[inclyding 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