Exam 1 Clinical Cases (Bacteria)

Question 1

A young woman develops a 102F fever 2 days after menses. She reports using tampons. After several days, the fever is accompanied by dizziness, hypotension, myalgias, and a diffuse rash on the chest. With a penicillinase-resistant penicillin and IV fluids, the symptoms resolve within 2 weeks. A desquamation of the palms is observed throughout the convalescence

Answer 1

Staphylcoccus aureus (toxin mediated)

BUZZ WORDS: tampon, shock-like symptoms (Toxic Shock Syndrome)

Question 2

An IV drug user presents with a high fever and signs of heart failure. A notable murmur prompts an ECG that reveals tricuspid valve vegetations. The patient is immediately begun on IV penicillinase-resistant penicillin that proves to be effective

Answer 2

Staphylcoccus aureus (infections)

BUZZ WORDS: IV drug use, acute onset, new murmur (Infective endocarditis caused by S. aureus)

Question 3

Ten days after undergoing chemotherapy for non-Hodgkin’s lymphoma, a middle-aged man develops a fever. On exam, he has erythema and tenderness at the insertion site of the IV catheter Blood cultures are positive. The original catheter is removed and the patient is started on vancomycin

Answer 3

Staphylcoccus epidermidis

BUZZ WORDS: indwelling foreign body infection, immuno-compromised (S. episdermidis is normal flora on skin)

Question 4

A sexually active young woman develops dysuria, pyuria, and fever suggestive of UTI. Urine cultures show G+ bacteria in clusters that are catalase +, coagulase -. The patient is started on TMP-SMX

Answer 4

Staphylcoccus saprophyticus

BUZZ WORDS: G+ cluster, catalase + (staph), coagulase - (either S. epidermidis or S. saprophyticus), and UTI post sex

Question 5

A young child presents with fever and a skin rash localized around the lips and on his arms. The rash appears pustular with yellow crusts. Cultures from the impetigo show Gram + cocci in chains that are B-hemolytic. The doctor administers penicillin G and warns the parents that the child may develop transient smoky-colored urine soon.

Answer 5

Streptococcus pyogenes (Group A, infections)

BUZZ WORDS: G+ Cocci in chains that are B-hemolytic (either S pyogenes- Group A- or S agalactiae- Group B). Localized rash with pustular yellow crusts is consistent with strep skin infections

Question 6

A young girl is brought to her doctor because of a rough-appearing rash on her trunk and neck that has spread to her arms. PE reveals that her axilla is most affected, but her palms and soles are spared. Her parents say that she has been suffering from a fever and sore throat. Lab studies reveal her serum is ASO+, and she is administered with penicillin. In a few days, her rash subsides and her palms and soles desquamate.

Answer 6

Streptococcus pyogenes (Group A, toxin-mediated)

BUZZ WORDS: ASO+ (indicative of strep A; it’s the titer that detects anti-streptolysin O antibodies). Fever, “sandpaper rash” that starts from the trunk and desquamation of palms and soles after rash subsides are consistent with Scarlet Fever

Question 7

An adolescent presents to the clinic complaining of brownish urine that started the day before. Two weeks earlier, he had a sore throat that resolved. PE reveals high BP and slight swelling around his eyes. Serum studies are significant for elevated BUN and Cr, ASO+, and diminished levels of C3 (complement protein). In addition, urinalysis indicates protein and RBC casts. Although a kidney biopsy was not performed, if it were, EM studies would likely reveal subepithelial humps in the glomerullus

Answer 7

Streptococcus pyogenes (Group A, immune-mediated)

BUZZ WORDS: Sore throat with ASO+ in serum (indicative of a prior strep A infection). Humps in the glomerulus clues us to glomerulonephritis caused by deposition of immune complexes on glomerular basement membrane in response to streptococcal infection

Question 8

Soon after birth, an infant develops seizures, a marked irritability, poor feeding, and fever. The infant’s birth records note a prolonged labor with premature rupture of membranes. An lumbar puncture was done and the infant was started on antibiotics.

Answer 8

Streptococcus agalactiae (Group B Streptococci)

BUZZ WORDS: Soon after birth, prolonged labor with premature rupture of membranes.

Question 9

An elderly man develops low-grade fever and signs of endocarditis over a period of 2 weeks. Following blood culture, his doctor also becomes concerned about possible colon cancer

Answer 9

Streptococcus bovis (Group D Streptococci, nonenterococcus)

BUZZ WORDS: endocarditis in the elderly, colon malignancy

Question 10

An elderly woman presents with a cough producing rusty-colored sputum. She complains of sharp right-sided chest pains, chills, and fever. PE reveals increased fremitus, dullness to percussion, and bronchial breath sounds on the lower right side. CXR shows right lower lobe consolidation, and Gram stain of sputum shows Gram + diplococci.

Answer 10

Streptococcus pneumoniae (aka pneumococci)

BUZZWORDS: Gram positive diplococci should be enough to clue you in to this. CXR infiltrate + symptoms consistent with pneumonia.

NOTE: penumococci is the major cause of community-acquired pneumonia, S. aureus is the major cause of hospital-acquired pneumonia

Question 11

A middle-aged woman presents with low-grade fever and general malaise. PE reveals Janeway lesions, Osler’s nodes, Roth’s spots, and splinter hemorrhages under her fingernails. ECG indicates vegetations on the mitral valve. In the doctor’s office, she recounts a dentist appointment a few weeks ago and several bouts of sore throat as a child

Answer 11

Streptococcus viridans

BUZZWORDS: Valve vegetation means it is endocarditis. Several bouts of sore throat indicates potential past persistent strep A infection (inferring existing valve damage, a hallmark of viridans endocarditis). Dental appointment a few weeks ago confirms viridans (colonizes oral cavity) to be the major pathogen at play.

Question 12

An old man develops a UTI 5 days after admission to the ospital. His record indicates that he is receiving antibiotic treatment including cephalosporins for an unrelated infection. In treating the patient, hysicians check for resistance to vancomycin

Answer 12

Enterococcus

BUZZWORDS: UTI post normal flora suppression by cephalosporins

Question 13

A young man enters the emergency room dehydrated, afebrile, and complaining of nausea and vomiting. Since he began vomiting 1 hour ago, he has been “hugging the toilet” nearly every 10 minutes. He remembers eating a dish with fried rice at an asian restaurant several hours ago

Answer 13

Bacillus cereus

BUZZWORDS: food poisoning, acute onset, “fried rice”

Question 14

A 33-year-old woman presents with an ulcerous lesion on the neck. The ulcer has a blackened necrotic eschar surrounded by edema. The woman first noticed the lesion 2 weeks ago as a painful, small red macule that gradually developed into an ulcer and, over the last few days, became painless. On the occupational history, the patient reveals that she works in the imported wool and hides industry

Answer 14

Bacillus anthracis (Cutaneous Anthrax)

BUZZ WORDS: wool and hides industry, cutaneous lesion

NOTE: Inhalation anthrax leads to systemic toxicity–> 100% mortality

Question 15

A teenage girl enters the emergency room suffering from painful muscle spasm. She sustains a facial sneer, a stiff arched back, clamped palms, and stiff jar. The father boasts how a week ago, she continued a soccer game even after falling on a nail in the field

Answer 15

Clostridium tetani (Tetanus, Lockjaw)

BUZZWORDS: traumatic injury involving rusty metals, uncontrolled muscle tension, and stiff jaw

Question 16

A woman straggles into the ER with a marked paralysis of her upper body. She describes the paralysis as a weakness that began in her neck and spread to her arms. She also complains of blurred double vision and requests water to sooth her dry throat. Although she has no fever, she appears quite dizzy and her eyelids are drooping. The day before, she returned from a camping trip where she insists she maintained good hygiene, eating canned foods only

Answer 16

Clostridium botulinum (Botulism)

BUZZWORDS: canned foods (spore-forming pathogen), symmetric descending paralysis spreading from head to extremeties

Question 17

An old woman comes to the doctor with a fever and loose bowels. Her diarrhea occurs in tremendous volumes. She complains although she does not remember ever seeing blood. She an unremarkable recent past medical history, except for an infection a few weeks earlier that was treated with clindamycin. Sigmoidoscopy of her colon reveals yellow-white plaques, which the doctor predicted after analyzing her stools for toxins

Answer 17

Clostridium difficile

BUZZWORDS: watery, non-bloody diarrhea post antibiotics treatment; yellow-white plaques (pseudomembranes) in her colon; stool analysis for toxins to confirm diagnosis

Question 18

A man enters the ER claiming to have been stabbed 2 days earlier. Muscles in his arm hurt, and on palpation, small air bubbles are felt below the skin. The wound area exudes a blackish, ill-smelling fluid and generates a crackling sound when touched. The patient has a fever, hypotensive, marked tachycardia, and has urinated very little since his injury. The doctors decide to amputate the arm, as well as monitor the patient for shock and renal failure.

Answer 18

Clostridium perfringens (Gas Gangrene)

BUZZWORDS: small air bubbles below the skin (caused by degradative enzymes); muscle cell necrosis (alpha toxin); and black fluide exudate leaking from skin

Question 19

A mother brings her 2-month old to the hospital because she exhibits fever, convulsions, irritability, and poor eating. The pediatrician in training notes widespread rash and a stiff neck on PE. She orders a spinal tap that reveals low glucose, high PMNs, high protein, and Gram + rods with “tumbling” motility in cultures.

Answer 19

Listeria monocytogenes (Meningitis)

BUZZWORDS: stiff neck, fever, and poor eating (meningitis); High PMNS, high protein, low glucose are signs of a bacterial infection; Gram + rods with tumbling motility is the hallmark of listeria (actin-based motility)

Question 20

A young immigrant girl goes to the doctor complaining of a sore throat and difficulties in breathing and swallowing. Her voice is unusually nasal and a large gray mucous film is noticed on the oropharynx. Her BP is low, lungs edematous, and her neurological examination shows cranial nerve problems.

Answer 20

Corynebacterium diptheriase (Diptheria)

BUZZWORDS: immigrant (possibly unvaccinated); strep-like symptom with gray mucous film instead (hallmark of diptheria). Cranial nerve palsy is caused by diphtheria toxin (AB toxin that prevents protein synthesis)

Question 21

A 45 year old man presents with multiple sinuses on the left side of his face. The sinuses discharge pus and are painless. His past medical history is insignificant except for a dental surgery done a few weeks ago for a dental infection. His dctor examines the pus under the microscope and finds filamentous organisms. The doctor rules out Nocardia by lack of acid-fast staining and makes the diagnosis by noting sulfur granules.

Answer 21

Actinomyces israelli (Actinomycosis)

BUZZWORDS: filamentous organisms; lack of acid-fast staining and presence of sulfur granules; dental surgery.

Question 22

A heart transplant patient on immunosuppressants develops slight fever, weight loss, and a cough, producing a viscous purulent sputum. The patient explains that these symptoms come and go over weeks and generally do not both him enough for a check up. The doctor decides to take a CXR, which reveals small abscesses with sinus tracts in the lung. A biopsy of the lung tissue reveals a filamentous, acid-fast, Gram + microorganism.

Answer 22

Nocardia (Pneumonia)

BUZZWORDS: Gram+, acid-fast staining, and filamentous organism.

Question 23

A young soldier in an army base enters the ER with a petechial rash, fever, and headache. PE shows + Kernig’s sign, nuchal rigidity, and impaired mental status. An lumbar puncture is performed showing increased PMNs, increased proteins, decreased glucose, as well as intracellular kidney bean-shaped diplococci.

Answer 23

Neisseria meningitidis (meningitis)

BUZZWORDS: + Kernig’s sign is indicative of meningitis (along with other symptoms). Increased PMNs, increased proteins, and decreased glucose shows bacterial infection. Intracellular kidney bean-shaped diplococci is indicative of N meningitidis.

NOTE: Streptococcus pneumoniae is also a meningitis-causing diplococci. We can differentiate the two by their Gram staining patterns (S. penumoniae is G+, N meningitidis is G-). In our scenario, the Gram staining pattern is not given, but we can infer that it is more likely caused by N. meningitidis because the patient lives in close quarters with others- a risk factor for N meningitidis.

Question 24

A teenager complains of pain during sexual intercourse and irregular intermenstrual bleeding. She has also begun to experience lower abdominal pain. A pelvic exam reveals a yellow mucopurulent discharge; Gram stain of discharge reveals Gram - intracellular diplocci.

Answer 24

Neisseria gonorrhoeae (Gonorrhea)

BUZZWORDS: STI with vaginal discharge. Gram negative intracellular diplocci narrows it down to N gonorrhoeae

Question 25

An alcoholic presents with a fever pleuritic chest pain, dyspnea, and cyanosis. His cough produces a bloody “current-jelly” sputum. CXR shows inflammation involving the right upper lobe with possible cavities.

Answer 25

Klebsiella pneumoniae (Pneumonia)

BUZZWORDS: pneumonia in an alcoholic; current-jelly sputum

NOTE: 3 risk factors for Klebsiella are Alcoholism, Aspiration, and Abscesses (AAA). It is also a nosocomial bacteria

Question 26

A series of patients in a small town visit the hospital complaining of bloody diarrhea, fatigue, and confusion. PE reveals neurological deficits, and laboratory tests show anemia, thrombocytopenia, and uremia. After careful questioning, the doctors discover that each patient frequents the same fast-food burger joint. The physicians identify the causative agent with serological testing and stool cultures appearing metallic green

Answer 26

Escherichia coli

BUZZWORDS: bloody diarrhea (EHEC) transmitted through contaminated food

NOTE: Other E colis- ETEC (traveler’s diarrhea), EPEC (EHEC without shiga-like toxin)

Question 27

A woman who recently returned from a trip to South America complains of a persistent high fever, malaise, and constipation that has lasted for over a week. She recalls that the fever began slowly and climbed its way up to the current 41C. A physical exam reveals that she has an enlarged spleen and a generally tender abdomen with red macules.

Answer 27

Salmonella typhi (Typhoid fever)

BUZZWORDS: fever accompanied by red macules

Question 28

A veterinary school student complaints to the doctor of diarrhea and abdominal tenderness. He is certain that these symptoms followed nausea and vomiting the day before. He admits that he may have caused himself this misery by excessively playing with his turtle

Answer 28

Salmonella enteritidis (Gastroenteritis caused by Non-Typhi salmonella)

BUZZWORDS: Gastritis; Playing with his turtle (animal–> human transmission)

Question 29

A photographer for National Geographic returning from Thailand develops a fever and abdominal cramps on the plane. By the time the plane lands, he suffers from bloody diarrhea. His fever peaks at 40C. The doctor decides to do an endoscopy exam and makes a diagnosis based on the hemorrhagic mucosa and ulcerations observed in the distal colon.

Answer 29

Shigella dysenteriae (Dysentery)

BUZZWORDS: bloody diarrhea, fever, and ulcerations in the distal colon

Question 30

A man visiting India arrives in the ER with signs of severe dehydration. He is thirsty, has decreased skin turgor and tachycardia.He abruptly began to suffer from diarrhea this morning and complains about the magnanimous watery volumes he is excreting. He has no fever, and the doctor treats with fluid and electrolytes

Answer 30

Vibrio cholerae (Cholera)

BUZZWORDS: magnanimous watery volumes of diarrhea; signs of dehydration; afebrile

Question 31

An elderly diabetic woman, who recently began swimming to control her weight. complains of painful discharge from her left ear. PE shows extreme tenderness of the left tragus. A swab clture of the ear reveals blue-green colonies emitting a fruity odor.

Answer 31

Pseudomonas aeruginosa (external otitis)

BUZZWORDS: recent water exposure; otitis; diabetic

NOTE: pseudomonas can also cause pneumonia (transmitted through moisture. Remember UW’s outbreak via a/c ducts recently?)

Question 32

A man and his two sons just returned from a vacation on their relative’s farm. All 3 arrive complaining of bloody diarrhea. The youngest son recovers spontaneously. The older son complains of right flank pain, while the father starts to notice tenderness in his joints. One surgeon,w worried about appendicitis in the older son, performs the initial incisions and discovers a normal appendix but an inflamed colon. After also observing swollen mesenteric lymph nodes, he makes a diagnosis.

Answer 32

Yersinia entercolitica

BUZZWORDS: enterocolitis (bloody diarrhea); mesenteric adenitis. Adults usually present with bloody diarrhea + arthritis; children present with bloody diarrhea + appedicitis-like pain

Question 33

An aged man comes to the hospital complaining of upper abdominal pains, which become worse after a meal. The doctor was about to prescribe an H2 blocker and send him on his way, however, biopsy of the stomach mucoas and urease positive breath test lead the doctor to prescribe antibiotics in addition to peptic ulcer treatment.

Answer 33

Helicobacter pylory

BUZZWORDS: Upper abdominal pains after a meal; positive urease breath test

Question 34

A man with fever, muscle pains, and headache feels no need to go to the doctor until about 1 day later, when he develops bloodty diarrhea and abdominal pain as well. The abdominal pain is so severe that his physician fears appendicitis until learning that the man may have had unpasteurized milk in the past week. A definitive diagnosis is made by growth on stool culture at 42C, microaerophilic conditions

Answer 34

Campylobacter jejuni

BUZZWORDS: transmitted by unpasteurized milk; bloody diarrhea; grows at 42C microaerophilic conditions

NOTE: Guillain-Barre Syndrome is often a complication of Campylobacter infections

Question 35

A 1-year-old infant develops a fever but really begins to alarm her parents when she seems unusually drowsy. The parents bring her to the hospital and the doctor notices neck rigidity and occasional seizures. The doctor identifies an organism in the infant’s cerebrospinal fluid that requires both hemin and NAD to grow. The infant recovers after ceftriaxone is administered but seems to have acquired a partial hearing loss

Answer 35

Hemophilus influenzae type B (Meningitis)

BUZZWORDS: hemin and NAD (chocolate agar); meningitis

NOTE: epiglottitis is also often associated with H influenzae type B infections. It is one of the most common causes of meningitis in children 6 months to 6 years (along with S penumoniae, N meningitidis). The incidence of H influenzae meningitis has decreased due to successful vaccination

Question 36

A 67 year old man with a history of heavy drinking comes to the doctor complaining of “the flu”. He has a fever, loss of appetite, headache, chest pain, and a mild cough producing little sputum. The doctor believes that the water diarrhea that he also suffers from is related. Sputum sample reveals many neutrophils but no bacteria. CXR reveals nodular infiltrates.

Answer 36

Legionella penumophilia (Atypical pneumonia)

BUZZWORDS: little/no sputum cough in pneumonia is typically atypical. Inability to see bacteria on Gram staining is indicative of legionella (poor gram stains; visualized with silver stain).

NOTE: Common causes of atypical pneumonia- mycoplasma, legionella, chlamydia

Question 37

An infant born in a rural area is brought to the ER with severe bouts of coughing throughout the day. During the visit, the baby appears cyanotic and suffers an attack of many coughs on a single expiration followed by a deep inspiration. The coughs produce copious greenish phlegm. Further history reveals that the infant has not been vaccinated.

Answer 37

Bordetella pertussis (Whooping Cough)

BUZZWORDS: unvaccinated child with bouts of many coughs; followed by whooping inspiration

Question 38

A homeless man enters the hospital with wasting and fever. He has had a chronic cough for several months producing bloody sputum as well as night sweats. CXR reveals cavitations with air-fluid levels in the apex of his left lung. Diagnosis is confirmed by an acid-fast stain of sputum

Answer 38

Mycobacterium tuberculosis (TB)

BUZZWORDS: cavitations with air-fluid levels (TB); acid-fast staining indicates mycobacterium

NOTE: there are only 2 clinically important bacteria that are visualized by acid-staining- nocardia and mycobacterium. Nocardia causes pneumonia, not TB.