Midterm

Question 1

A 70 year old male ICU patient had a chest Xray with hazy infiltrates and was diagnosed to have pneumonia. Vital signs include: BP 110/70, CR 65, RR 28, Temp 41°C. Patient also complained of diarrhea. Laboratory tests result include: Na 121, K 3.5, elevated AST and ALT. Culture using charcoal-yeast extract reveals a gram-negative bacilli. What is the MOST LIKELY etiologic agent for this case?
A. Streptococcus pneumoniae    
B. Pseudomonas aeruginosa   
C. Mycoplasma pneumoniae   
D. Haemophilus influenza   
E. Legionella pneumophilia

Answer 1

E. Legionella pneumophilia

Clinical clues suggestive for Legionnaires’s disease: Diarrhea, high fever (>40°C). Numerous neutrophils but no organisms revealed by Gram staining of respiratory secretions, hyponatremia. Relative bradycardia has been overemphasized as a useful diagnostic finding.

Question 2

The drug of choice for Legionella infection?
A. Azithromycin   
B. Ceftriaxone   
C. Ciprofloxacin   
D. Tetracycline   
E. Trimethoprim-Sulfamethoxazole

Answer 2

A. Azithromycin

SIMILAR TO PREVIOUS BOARD EXAM CONCEPT/PRINCIPLE:
The macrolides (especially azithromycin) and the respiratory fluoroquinoles are now the antibiotics of choice.
Ciprofloxacin is not a respiratory fluoroquinolone.

Question 3

Mr. Malibog is diagnosed with syphilis. He is given a single dose of Pen G 2.4 mU IM. The test used to monitor response to therapy for primary syphilis is:
A. Non treponemal tests   
B. Treponemal tests   
C. PCR   
D. Microscopic agglutination test   
E. Dark-field microscopy

Answer 3

A. Nontreponemal tests

SIMILAR TO PREVIOUS BOARD EXAM CONCEPT/PRINCIPLE:
RPR or VDRL is used for quantitative measurement of antibody to assess clinical syphilis activity or to monitor response to therapy. After therapy of early syphilis, a presistent fall by fourfold or more (e.g. 1:32 to 1:8) is considered an adequate response.

Question 4

A 10-year old post-splenectomy boy with sickle cell disease complains of pain in the right tibia and local inflammation is noted. Osteomyelitis is diagnosed. The MOST LIKELY etiologic agent is:
A. Listeria   
B. Salmonella   
C. Shigellosis   
D. Campylobacter   
E. S. aureus

Answer 4

B. Salmonella

Patients with sickle-cell anemia are particularly prone to Salmonella osteomyelitis

Question 5

This virulence factor is associated with invasiveness of Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) infections.
A. Protein A    
B. Panton-Valentine Leukocidin   
C. Coagulase   
D. O antigen   
E. Fimbriae

Answer 5

B. Panton-Valentine Leukocidin

SIMILAR TO PREVIOUS BOARD EXAM CONCEPT/PRINCIPLE:
There is a strong epidemiologic association linking the presence of the gene for the Panton-Valentine leukocidin with skin and soft tissue infections as well as with invasive infections such as necrotizing pneumonia

Question 6

The following viruses undergo replication in the cytoplasm, EXCEPT:
A. Poxviridae   
B. Reoviridae   
C. Picornaviridae   
D. Rhabdoviridae   
E. Orthomyxoviridae

Answer 6

EXCEPT: E. Orthomyxoviridae

Most DNA viruses replicate in the nucleus, EXCEPT poxviridae;

Most RNA viruses replicate in the cytoplasm, EXCEPT retroviridae and orthomyxoviridae.

Question 7

The definitive diagnosis of enteric fever requires the isolation of S. typhi. Stool cultures usually become positive during:
A. 1st week   
B. 2nd week  
C. 3rd week   
D. 4th week   
E. Always positive

Answer 7

C. 3rd week

SIMILAR TO PREVIOUS BOARD EXAM CONCEPT/PRINCIPLE: Stool cultures usually become positive during the third week of infection in untreated patients.

Question 8

The β-hemolysis of blood agar observed with Streptococcus pyogenes is due to the presence of:
A. Streptolysin   
B. M-protein  
C. Hyaluronic acid  
D. Catalase   
E. Coagulase

Answer 8

A. Streptolysin

Streptolysin is reponsible for beta-hemolysis.

Question 9

Dermatophytes are fungi that infect the epidermal tiussue by invading and attacking:
A. Collagen   
B. Keratin   
C. FIbroblasts   
D. Sebaceous glands   
E. Vimentin

Answer 9

B. Keratin

Dermatophytes secrete an enzyme called keratinase, which digests keratin.

Question 10

The causative agent for herpangina:
A. Coxsackievirus A   
B. Coxsackivirus B   
C. Echovirus   
D. Rhinovirus   
E. Norwalk virus

Answer 10

A. Coxsackievirus A

Coxsackievirus A causes herpangina, which is a mild self-limiting illness characterized by fever, sore throat, and small red-based vesicles over the back of the throat.

Question 11

A 12-year old leukemic boy complains of severe headache and fever. PE reveals positive Brudzinski. CSF analysis reveals increased opening pressure and the cell count is elevated, while the glucose is low. Special staining showed spherical budding yeast cells surrounded by a thick non-staining capsule. What is the MOST LIKELY causative agent for this case?
A. Aspergillus   
B. Pneumocystis   
C. Candida   
D. Cryptococcus   
E. Coccidioides

Answer 11

D. Cryptococcus

The key to diagnosis of Cryptococcus infection is doing a lumbar puncture and analyzing the CSF.

An india ink stain shows yeast cells with surrounding halo, the polysaccharide capsule. Culture will confirm the diagnosis.

Question 12

The following virus are enveloped, EXCEPT:
A. Herpesviridae   
B. Poxviridae   
C. Flaviviridae   
D. Bunyaviridae   
E. Reoviridae

Answer 12

EXCEPT: E. Reoviridae

Reoviridae is a naked double-stranded RNA virus, the rest are enveloped viruses.

*Remember:
Naked DNA viruses: A woman must be naked for the PAP smear exam (Papova, Adeno, Parvo);

Naked RNA viruses: Picorna, Calici, Reo.

Question 13

A 25 year old male complains of urethral discharge. You perform a Gram stain on a specimen of the discharge and on microscopy you noted gram negative dipplococci within PMN. What is the next step to be done?
A. Treat the patient with ceftriaxone   
B. Do latex agglutination   
C. The specimen should be cultured   
D. Confirm the test by serologic test   
E. None of the above

Answer 13

A. Treat the patient with ceftriaxone

A rapid diagnosis of gonococcal infection in men may be obtained by Gram’s staining of urethral discharge.

The detection of gram-negative intracellular diplococci is highly specific and sensitive in diagnosing gonococcal urethritis in symptomatic males.

Question 14

This water-borne parasite penetrate through exposed skin and invade the venous system, where they mate and lay eggs. These eggs may be deposited in the liver leading to fibrosis, which causes blockage of the portal venous system. Which of the following serves as its intermediate host?
A. Oncomelania   
B. Sundathephusa   
C. Pomacea   
D. Glossinia   
E. Anopheles

Answer 14

A. Oncomelania

Sundathephusa - Paragonimus;

Glossinia - Trypanosoma brucei;

Malaria - Anopheles

Question 15

A 37-year old woman is admitted to the hospital following abrupt onset of chills, fever, headache, and prostration. She has non-productive cough. Chest X-ray revealed no consolidation and no alveolar exudate. She is diagnosed to have primary atypical pneumonia. Which is LEAST likely cause of this condtion?
A. Mycoplasma pneumoniae  
B. Chlamydia pneumoniae  
C. RSV   
D. Klebsiella pneumonia   
E. Legionella pnuemophilia

Answer 15

D. Klebsiella pneumonia

Etiologic agents for "atypical' pneumonia:
M. pneumoniae
C. pneumoniae
Legionella;
Respiratory viruses.

Question 16

Which of the following events is MOST likely due to bacterial transformation?
A. A strain of P. aeuroginosa produces beta-lactamase encoded by a plasmid similar to a plasmid of another gram-negative bacteria
B. An encapsulated strain of S. pneumoniae acquires the gene for capsule formation from an extract of DNA from another encapsulated strain
C. A gene encoding resistance to gentamicin in E. coli chromosome appears in the genome of a virulent bacteriophage that has infected E. coli
D. A gene encoding resistance to gentamicin, tetracycline, and sulfonamide in the E. coli plasmid appears in teh genome of another gram-negative S. dysenteriae
E. None of the above

Answer 16

B. An encapsulated strain of S. pneumoniae acquires the gene for capsule formation from an extract of DNA from another encapsulated strain

Transformation involves recombination of genetic material from a purified DNA taken up by a cell

Question 17

A 40 year old male develops right upper quadrant pain and fever. Laboratory findings reveal leukocytosis, elevated alkaline phosphatase and elevated ESR, HBSAg is negative. Ultrasound reveals a space occupying lesion in the right lobe of the liver. If amebic liver abscess is considered, the following statement is true:
A. A positive antibody to E. histolytica antigen is highly sensitive and specific
B. Most have concurrent signs or symptoms of colitis
C. Most patient have trophozoites seen in their stools
D. Rupture of an amebic liver abscess into the peritoneum is always managed surgically
E. A larger dose of Metronidazole is needed for treatment of amebic liver abscess

Answer 17

A. A positive antibody to E. histolytica antigen is highly sensitive and specific

When a patient has a space-occupying lesion of the liver, a positive amebic serology is highly sensitive and highly specific. Most individuals with amebic liver abscess do not have concurrent signs or symptoms of colitis, and most do not have E. histolytica trophozoites in theri stools. Rupture of an amebic liver abscess into the peritoneum is generally managed conservatively, with medical therapy and percutaneous catheter drainage of fluid collections as needed. Remarkably, given the larger size of amebic liver abscesses, treatment with metronidazole in the same doses used for amebic colitis is almost always successful.

Question 18

The drug of choice for Neurocysticercosis:
A. Diethylcarbamazine   
B. Thiabendazole   
C. Praziquantel  
D. Ivermectin   
E. Niclosamide

Answer 18

C. Praziquantel

Neurocysticercosis can be treated medically with albendazole or praziquantel.

Question 19

Which statement is TRUE for HIV infections?
A. Maternal transmission to the fetus occurs most commonly in the perinatal period
B. The most common mode of infection is homosexual
C. There is higher risk of HIV transmission associated with unprotected receptive vaginal intercourse compared to unprotected receptive anal intercourse
D. Post-exposure prophylaxis may include a combination of 2 Non-nucleoside reverse transcriptase inhibitors
E. The standard blood screening test for HIV infection is the Western blot

Answer 19

A. Maternal transmission to the fetus occurs most commonly in the perinatal period

HIV is predominantly a sexually transmitted disease, the most common mode of infection is heterosexual. There is elevated risk of HIV transmission associated with unprotected receptive anal intercourse among both men and women compared to the risk associated with receptive vaginal intercourse. Post-exposure prophylaxis may include combination of 2 NRTIs. The standard screening test for HIV is the ELISA.

Question 20

A 34 year old man is diagnosed with borderline leprosy, a month after initiation of appropriate treatment, his lesions becomes more tuberculoid. This type of reaction is termed:
A. Downgrading reaction   
B. Reversal reaction   
C. Type 2 lepra reaction   
D. Erythema nodosum leprosum   
E. Lucio's phenomenon

Answer 20

B. Reversal reaction

Type 1 lepra reactions occur in patients with borderline forms of leprosy. When type 1 lepra reaction precede the initiation of appropriate antimicrobial therapy, they are termed downgrading reactions, and the case becomes histologically more lepromatous. When they occur after the initiation of therapy, they are termed reversal reactions, and the case becomes more tuberculoid.

Type 2 lepra reactions:erythema nodosum leprosum (ENL) occurs exclusively in patients near the lepromatous end of the leprosy spectrum (BL-LL).

Lucio’s phenomenon is seen in patients who have the diffuse lepromatosis form of lepromatous leprosy, most often whose who are untreated.