Internal medicine - Infectology Flashcards
INT - 18.1
Serologic test results after Hepatitis B vaccination:
A) HBsAg positive
B) anti-HBs positive
C) anti-HBc positive
D) anti-HCV positive
ANSWER
B) anti-HBs positive
EXPLANATION
Hepatitis B vaccine contains only the surface antigen of Hepatitis B virus. After the vaccine is given, the body makes antibodies against this antigen therefore other test results should not be positive.
INT - 18.2
Definition of sepsis:
A) intermittent fever
B) bacteraemia
C) elevated ESR (erythrocyte sedimentation rate) and fever
D) a condition involving organ disfunction due to systemic immune response in which the role of infection can be seen or suspected
ANSWER
D) a condition involving organ disfunction due to systemic immune response in which the role of infection can be seen or suspected
EXPLANATION
Sepsis is the body’s overwhelming and life-threatening response to infection that can lead to tissue damage, organ failure, and death. It is the body’s over active and toxic response to an infection.
INT - 18.3
Which of the following statements is true about antibiotic therapy in severe sepsis?
A) definitive antimicrobial therapy based on the results of blood culture and sensitivity test
B) initial empiric therapy with the intent to cover multiple possible pathogens commonly associated with the septic focus
C) combination of at least two bactericidal antibiotics
D) the newest and the most expensive antibiotic should be administered
ANSWER
B) initial empiric therapy with the intent to cover multiple possible pathogens commonly associated with the septic focus
EXPLANATION
If severe sepsis is suspected empiric antibiotic therapy must be started immediately after performing of specimen collection for microbiological testing. Delay in antibiotic treatment increases mortality based on clinical trials.
INT - 18.4
The role of Streptococcus pneumoniae should be considered in community acquired pneumonia in which of the following cases?
A) always
B) if the patient underwent splenectomy
C) if the patient has chest pain when breathing and has purulent sputum
D) if there is a lobar consolidation on the chest X-Ray
ANSWER
A) always
EXPLANATION
The role of S. pneumoniae should always be considered in communitiy acquired pneumonia because this is the most common cause at every age in both mild and severe pneumonia. Lack of symptoms and X-ray signs does not exclude S. pneumoniae caused pneumonia.
INT - 18.5
A patient has trismus, risus, sardonicus and opisthotonus. What is the most likely diagnosis?
A) plague
B) gas gangrene
C) tetanus
D) rabies
ANSWER
C) tetanus
EXPLANATION
Trismus, risus sardonicus and opisthotonus are the characteristics of tetanus. Neurotoxins of Clostridium tetani increase excitability of the nerves causing muscle spasm and spastic paralysis.
INT - 18.6
A 60-year-old patient presents to his primary care provider with headache and severe muscle pain. He has fever, itchy skin, and periorbital oedema. Two weeks ago he ate wild boar (which was cooked rare). His blood tests reveal elevated CK (creatine kinase) and eosinophilia. What is the most likely diagnosis?
A) Salmonellosis
B) Trichinellosis
C) Echinococcosis
D) Dysentery
ANSWER
B) Trichinellosis
EXPLANATION
The clinical signs and symptoms (incubation period, periorbital oedema, muscle pain, itchy skin, fever, diarrhea an eosinophilia) and the history of eating wild boar refer to trichinellosis. In Hungary trichinellosis mainly occur in wild boars but in other areas such as in Transylvania domestic pigs can also be infected.
INT - 18.7
A 19-year-old student boy has had sore throat for two weeks. A few days after the first symptoms he became febrile and generalized lymphadenopathy developed. He has lymphocytosis, thrombocytopenia and elevated liver enzymes. He lives in the countryside with a dog and a cat. Insects bite him frequently. What is the most likely diagnosis?
A) Lyme-disease
B) lymphoma
C) infectious mononucleosis
D) cat scratch disease
E) tularaemia
ANSWER
C) infectious mononucleosis
EXPLANATION
Infectious mononucleosis is most common in teenagers associated with sore throat, enlarged lymph nodes, hepatitis and lymphocytosis-monocytosis. Thrombocytopenia also occurs. 90 percent of adults develop infectious mononucleosis during their childhood.
INT - 18.8
Tetanus prophylaxis should be administered in which of the following cases?
A) Every type of injury apart from the age and the vaccination status of the patient.
B) Every type of injury if the patient has been vaccinated but the last dose had been given more than 5 years ago
C) Every type of injury if the patient has never been vaccinated.
D) In every case.
E) B+C
ANSWER
E) B+C
EXPLANATION
If the patient has been vaccinated or a booster has been given to him within 5 years, prophylaxis is not needed. If tetanus infection is suspected (contaminated wounds, burns, puncture wounds, etc.) and the patient had been vaccinated for more than 5 years tetanus toxoid should be administered. If tetanus infection is suspected but the patient has never been vaccinated or his vaccination status is unknown tetanus toxoid and immune globulin are both needed.
INT - 18.9
Adequate treatment of uncomplicated infectious mononucleosis is:
A) Doxycyclin
B) Ampicillin
C) Steroids
D) Symptomatic
E) Penicillin+ Steroids
ANSWER
D) Symptomatic
EXPLANATION
Infectious mononucleosis caused by a virus therefore antibiotics are not efficient. If ampicillin or amoxicillin are administered non-allergic type rash can develop. In uncomplicated cases symptomatic treatment is enough. If respiratory tract obstruction appear due to enlarged tonsils steroids can be given but there is no evidence about its effectiveness.
INT - 18.10
A patient has periodic attacks of sequential chills and fever, dark urine and hepatosplenomegaly. He has a history of returning from the tropics. What is the most likely diagnosis?
A) hepatitis A
B) malaria
C) plague
D) leprosy
E) none of the above
ANSWER
B)malaria
EXPLANATION
The patient’s history and symptoms refer to malaria which is a widespread disease in the tropics. Since the resistance against antimalarial drugs has increased in certain areas, malaria has to be considered even if the patient took prophyilactic drugs.
INT - 18.11
Which of the following treatment should be chosen in severe systemic enterococcal infection?
A) penicillin G + amikacin
B) vancomycin + ceftriaxon
C) ciprofloxacin + oxacillin
D) ampicillin + gentamicin
E) high-dose ampicillin
ANSWER
D) ampicillin + gentamicin
EXPLANATION
Ampicillin is the most effective antibiotic agent against enterococcal infections but it can not show bactericidal activity alone. In combination of ampicillin and gentamicin synergy mechanism develops leading to bactericidal activity. Synergy mechanism requires bacterial sensitivity to ampicillin without high resistance to gentamicin.
INT - 18.12
Screening and treatment of asymptomatic bacteriuria is required in which one of the following cases?
A) after catheter insertion
B) in diabetic females
C) in pregnant women
D) in patients using intermittent catheter due to transverse cord lesion
E) in patients who have permanent indwelling catheter
ANSWER
C) in pregnant women
EXPLANATION
Asymptomatic bacteriuria has to be screened and treated only if it can lead to such damage which is preventable by antibiotic treatment. Asymptomatic bacteriuria is relatively common in pregnant women, it often leads to pyelonephritis which is dangerous to both the fetus and the mother. Treating asymptomatic bacteriuria during pregnancy can prevent systemic infection therefore screening and treatment are recommended. In the other cases mentioned above systemic infection can not be prevented moreover antibiotic therapy could result in increased bacterial resistance to antibiotics or other side-effects such as Clostridium difficile associated diarrhoea so treatment in these cases is contraindicated.
INT - 18.13
What is the acceptable efficacy probability of an empiric (combined) antibiotic treatment chosen in severe life-threatening infection?
A) 50%
B) 60%
C) 80%
D) more than 90%
ANSWER
D) more than 90%
EXPLANATION
Based on international consensus empiric antibiotic treatment has to be at least 90% likely to be effective in severe infections.
INT - 18.15
How can you diagnose urinary tract infection in a febrile patient who has no other symptoms?
A) urinalysis shows pyuria and bacteriuria
B) urinalysis shows pyuria and urine culture is positive with the presence of uropathogen bacteria at high colony counts
C) permanent catheter using patient
D) the patient has pyuria and elevated CRP
ANSWER
B) urinalysis shows pyuria and urine culture is positive with the presence of uropathogen bacteria at high colony counts
EXPLANATION
In order to diagnose urinary tract infection in a febrile patient, urinalysis and urine culture tests have to be done. Pyuria and positive urine culture tests confirm the diagnosis. In the absence of any changes in diagnostic test results means that you have to looking for other cause of fever.
INT - 18.16
A 63-year-old patient had been treated with COPD for 2 weeks at the division of pulmonology where he got antibiotics and steroid bolus. Two days ago profuse diarrhea and fever have been started a few hours after eating chicken soup. Other members of his family (who ate with him) have no symptoms. Which of the following is the most likely cause of his symptoms?
A) salmonellosis
B) Clostridium difficile associated diarrhea
C) campylobacteriosis
D) intestinal tumor
ANSWER
B) Clostridium difficile associated diarrhea
EXPLANATION
Clostridium difficile is the most likely cause of acute diarrhea in patients with a history of hospitalization and antibiotic treatment, especially if other members of their family have no symptoms.
INT - 18.17
Which of the following is the most accurate step in diagnosis of Clostridium difficile associated diarrhea?
A) stool sample culture test
B) detection of Clostridium difficile A+B toxins in stool specimens
C) detection of Clostridium difficile antigen and pus in stool
D) history is enough
ANSWER
B) detection of Clostridium difficile A+B toxins in stool specimens
EXPLANATION
Clostridium difficile is naturally present in the guts of some humans therefore stool culture does not confirm the diagnosis. Detection of toxin in diarrheic stool proves pathogenic role of Clostridium difficile. If the toxin is detectable from stool with normal consistency it means carrier state.
INT - 18.18
Which of the following antimicrobial agents is recommended for use in methicillin-sensitive Staphylococcus aureus caused severe sepsis?
A) vancomycin
B) flucloxacillin
C) clindamycin
D) gentamycin
E) ceftriaxon
ANSWER
B) flucloxacillin
EXPLANATION
Antistaphylococcal penicillins are the most effective antibiotics against Staphylococcus aureus therefore this group of antibiotics is the best first choice in severe infections. If the patient has penicillin allergy (which has been confirmed) then first generation cephalosporins or glycopeptides could be used.
INT - 18.20
Which of the following diagnostic steps is required for the diagnosis of erythema migrans?
A) serology
B) culture
C) clinical features
D) histology
ANSWER
C) clinical features
EXPLANATION
When erythema migrans appears there is no immune response yet therefore serology is useless. Bacteria can be detected from the histological sample but performing a biopsy is not required for the diagnosis but unnecessary, difficult and expensive. The diagnosis is clinical.
INT - 18.22
Which of the following prophylaxis is recommended for patients underwent splenectomy?
A) pneumococcal, meningococcal and Haemophilus influenzae type b vaccines
B) crystalline penicillin for 2 weeks
C) pneumococcal vaccine
D) amoxicillin therapy for years
ANSWER
A) pneumococcal, meningococcal and Haemophilus influenzae type b vaccines
EXPLANATION
Splenectomized patients are at risk for uncontrolled severe infection caused by encapsulated bacteria because spleen has an important role to eliminate them. Vaccination against S. pneumoniae, N. meningitidis and H. influenzae b would be the best choice. Although according to international and Hungarian recommendations H. influenzae b vaccine doesn’t have to be taken due to its low prevalence in adults. Pneumococcal and meningococcal vaccines should be administered a few weeks before an elective splenectomy. If emergency splenectomy is inevitable vaccination has to be performed at least two weeks after the operation.
INT - 18.23
Which of the following antibiotics has no efficacy against Pseudomonas?
A) piperacillin/tazobactam
B) ciprofloxacin
C) ceftazidime
D) ceftriaxone
E) colistin
ANSWER
D) ceftriaxone
EXPLANATION
Ceftriaxone has no antipseudomonal activity.