Answers to Clinical Case Studies
CHAPTER 1 A Brief History of Microbiology
Clinical Case Study: Remedy for Fever or Prescription
for Death? (p. 16)
1. Unknown to the people of that era, mosquitoes rarely migrate farther than one
mile from their original birthplace. Many of the affluent (wealthy Philadelphians)
2. Early American settlers believed the cold weather somehow purified the air and
exposing themselves and even furniture to the frost was purifying. In a way, this
Clinical Case Study: Can Spicy Food Cause Ulcers? (p. 21)
1. To determine if a microbe caused ulcers, Dr. Koch would: (a) examine several cases
of stomach ulcer to see if the same microbe appears to be present in all cases; (b)
CHAPTER 2 The Chemistry of Microbiology
Clinical Case Study: Raw Oysters and Antacids:
A Deadly Mix? (p. 39)
1. Antacids raise the pH of the stomach, allowing more cells of Vibrio to survive and
cause disease.
3. Oyster lovers should acquire their treats from untainted waters, cook the oysters
CHAPTER 3 Cell Structure and Function
Clinical Case Study: The Big Game (p. 69)
1. The capsule of Streptococcus pyogenes allows the bacterial cells to adhere to tissues
and provides protection from the defensive cells of the body.
3. The bacterial cell wall contains peptidoglycan. The cell wall of Gram-positive
CHAPTER 6 Microbial Nutrition and Growth
Clinical Case Study: Cavities Gone Wild (p. 170)
1. Biofilms of dental plaque have led to the complete destruction of Daniel’s teeth.
Lesions in his mouth allowed bacteria to invade his blood and affect his heart. All of
2. Daniel needs to brush his teeth regularly to remove plaque buildup. His parents can
3. His parents should remove sucrose from his diet to inhibit the formation of
4. Biofilms are synergistic communities of microorganisms. By physically disrupting
Clinical Case Study: Boils in the Locker Room (p. 180)
2. Facultatively halophilic microbes can grow in high salt conditions but do not require
high salt.
4. After 24 hours, a single colony would contain (1 × 248) = 2.814 × 1014 cells.
Instructor’s Manual for Microbiology with Diseases by Body System, 5e
CHAPTER 7 Microbial Genetics
Clinical Case Study: Deadly Horizontal Gene Transfer (p.
230)
2. The patient was most likely infected as a result of urinary catheterization.
4. Hospital personnel should isolate the patient and be sure to follow high standards of
personal hygiene.
CHAPTER 10 Controlling Microbial Growth in the Body:
Antimicrobial Drugs
Clinical Case Study: Antibiotic Overkill (p. 297)
1. The powerful antibiotic had killed the bacterial microbiota present in the oral
mucosa and vagina. This allowed yeast to flourish, resulting in her symptoms.
3. She needs to be aware of opportunistic yeast infections when taking oral antibiotics
Clinical Case Study: Battling the Enemy (p. 299)
1. Semisynthetic refers to an antimicrobial drug that is formed from laboratory
modification of a natural antibiotic.
3. Resistance to beta-lactams is often due the synthesis of the bacterial enzyme beta-
lactamase.
Clinical Case Study: Tough Decision (p. 305)
1. Spectrum of action, efficacy (strain sensitivity to the drug), routes of administration
2. Because the risks of TB in the brain are more severe than the risks of multi-drug
treatment, the doctors decided to treat the child for MDR-TB. A six-week culture
CHAPTER 13 Characterizing and Classifying Viruses, Viroids, and
Prions
Clinical Case Study: Invasion from Within or Without? (p.
404)
1. The man has a prion-induced disease. There was no mention of a family history of
3. It is true that the young man was an avid hunter in the Colorado area and that
chronic wasting disease (similar to BSE) is prevalent in elk populations;
CHAPTER 14 Infection, Infectious Diseases, and Epidemiology
Clinical Case Study: A Deadly Carrier (p. 416)
1. When a large number of cases of a disease transmitted by the fecal-oral route occur
2. Public health officials could notify the community to boil all water before drinking
it or using it to prepare foods, wash dishes, brush teeth, and so forth. A privy could
Clinical Case Study: TB in the Nursery (p. 429)
1. Upper respiratory disturbances that coincide with fever should stimulate caregivers
to “THINK TB.” This was the national slogan for tuberculosis awareness several
Instructor’s Manual for Microbiology with Diseases by Body System, 5e
2. At a minimum, staff members with fever should be restricted from working with
patients.
3. Education is a powerful tool. Posters and other visuals could be used in waiting
CHAPTER 15 Innate Immunity
Clinical Case Study: Evaluating an Abnormal CBC (p. 451)
1. Remember that bleeding cleanses a wound of potentially infectious microbes and
that normal coagulation prevents the entry of microorganisms. A very low platelet
2. This patient is at risk for a fatal infection. He must be protected from anything that
interrupts skin integrity, which would place him at risk for an infection that he does
Clinical Case Study: The Stealth Invader (p. 458)
2. Interferons are anti-viral defenses. Mycoplasma is a bacterium.
4. Tar and other chemicals in smoke disrupt the proper action of mucous-secreting
CHAPTER 18 Immune Disorders
Clinical Case Study: The First Time’s Not the Problem (p.
531)
2. p. 545. Wash the area with soap. Cover the area with a baking soda paste. Then use
3. The different chemicals present in bee venom have various reactions on human
tissue.
a. Melittin causes red blood cells at the sting site to burst and the blood vessels
4. The son and father should be told to avoid scratching the area to prevent infection.
om.
6. In a severe allergic reaction, there is severe itching and pain and swelling. There will be
7. From
Avoid wearing shiny or brightly coloured clothing, flowery prints, or black, as
these seem to attract insects more than white, green, tan or khaki clothes
Wear shoes at all times when out of doors
Avoid using strong perfumes during the summer
Many products, such as suntan lotions, hairsprays, hair tonics and other cosmetics,
outside for some time, especially if you are alone
If a bee or wasp comes near you, do not try to swat the insect but move away
If you find many wasps or bees in your house or garden and suspect that there may
be a nest nearby – perhaps in the roof or a nearby tree – phone the local authority or
Clinical Case Study: A case of AIDS (p.544)
1.
a. Diagnosis involves detecting antibodies against HIV in the blood using enzyme–
linked immunosorbent assay (ELISA) and immunoblot testing. Most individuals
3. Pneumocystis pneumonia is an opportunistic infection that are ordinarily non-lethal. In
a HIV infection however, the body is not able to produce enough antibodies against
4. Proper use of gloves, protective eyewear, and masks to prevent contact with infected
CHAPTER 19 Microbial Diseases of the Skin and Wounds
Emerging Disease case Study: Buruli Ulcer (p. 555)
1. Organism produces a unique toxin – mycolactone – which causes tissue damage and
2. A long period of antibiotic therapy is needed because the antibiotics work only on
3. Mycobacterium ulcerans is usually seen in Sub saharan Africa. It needs a temperature
Emerging Disease case Study: A New Cause of Spots (p.
565)
1. Because the antibodies were specific for Rickettsia ricketsii, but the causative organism
is Rickettsia parkeri.
2. We have a very small sample to study. Polymerase Chain Reaction (PCR) helps make
3. pink – Gram negative
Answers to Clinical Case Studies
Clinical Case Study: A Painful Rash (p.569)
2. The presumptive diagnosis was Gas Gangrene. Gas gangrene had not appeared at the
3. Impetigo begins as red spots that turn to blisters that break open. The sores are not
painful. Not associated with fever. They are caused by Staphylococcus or Streptococcus.
5. A break in the skin contaminated by Clostridium which is present everywhere in soil,
water and sewage.
6. Clostridium releases 11 toxins that increases vascular permeability, and lyses
7. Even with the best treatment fatality exceeds 40%. The increase in vascular permeability
Clinical Case Study: A child with warts (p. 576)
2. p. 574: If there are cuts and abrasions on the skin the virus could spread.
4. No. The likelihood of warts becoming cancerous are only with genital warts.
Clinical Case Study: Grandfather’s Shingles (p.579)
1. Varicellovirus (varicella-zoster virus, VZV).
3. The new parents will not catch shingles, but they may get chickenpox if they have not
been vaccinated or if they have not had chickenpox themselves.
4. The newborns will not catch shingles, but they may get chickenpox, because they have
Clinical Case Study: Is it Athlete’s Foot (p.585)
1. p 584: Under Section ‘Diagnosis, Treatment, and Prevention’.
2. Since his nails are affected, he will need treatment with oral agents. His treatment will
Instructor’s Manual for Microbiology with Diseases by Body System, 5e
Clinical Case Study: Diagnosis in the desert (p. 587)
2. The women were infected by bites of infected biological vector – the sandfly (genera
Phlebotomus).
CHAPTER 20 Microbial Diseases of the Nervous System and Eyes
Emerging Disease Case Study: Melioidosis (p. 599)
2. The doctors did not expect meliodosis because it is an uncommon disease. And it is seen
in Southeast Asia rather than in Australia.
Clinical Case Study: The frowning Actor (p. 608)
1. Botox is a diluted toxin from Clostridium botulinum.
3. No.
5. Some of the injected Botox affected the muscles that keep the eyelids raised.
Clinical Case Study: A woman with no feelings (p. 614)
1. Diagnosis of leprosy is based on signs and symptoms of disease—a loss of sensation in
3. Therapy consists of administering multiple drugs, such as rifampin, clofazimine, and
4. Family members with whom she lives. Human leprosy is transmitted via person–to–
person contact, though leprosy is not particularly virulent. Individuals are typically
Clinical Case Study: A deadly mosquito bite (p. 617)
3. Since Zika virus is very small, it is difficult to detect it in Maria’s blood sample. Besides
Zika virus is a RNA virus. RNA is very difficult to handle and breaks easily. To
Clinical Case Study: A threat from the wild (p. 621)
2. Against the rabies virus
4. In this case the bat had landed on the person a month earlier. Unfortunately, by the time
symptoms appear and antibody production occurs, it is too late to intervene, and the
Clinical Case Study: A Protozoan mystery (p. 622)
1. African trypanosomiasis.
3. Trypanosoma brucei.
5. Pentamidine, suramin, Melarsoprol in case the disease has progressed to the CNS.
7. The biological vector is the Tsetse fly which lives in sub-equatorial savanna and riverine
Clinical Case Study: A very sick sophomore (p. 624)
1. Meningococcal meningitis.
3. White blood cells.
5. Who else in the dorm is infected. This infection spreads fast in close quarters.
CHAPTER 21 Microbial Cardiovascular and Systemic Diseases
Clinical Case Study: A Heart-Rending Experience (p. 637)
1. The client is a construction worker, and the E.coli could have entered the heart
2. The E.coli form colonies under the leaflets of the heart valve which then form
Clinical Case Study: Nightmare on the Island (p. 641)
1. Yersinia pestis
3. Gram negative
Clinical Case Study: A Sick Camper (p. 646)
2. If undiagnosed, the disease progresses to the next stage with neurological and cardiac
dysfunction. Later there is severe arthritis.
3. While the characteristic ‘Bull’s eye rash is not there, the other signs and symptoms and
4. Treatment with antimicrobial drugs such as doxycycline, cefuroxime, or amoxicillin
effectively cures most cases of Lyme disease in the first phase, though prolonged
5. Center for Disease Control (CDC). To keep track of spread of tick-borne diseases.
Clinical Case Study: A Tired Freshman (p. 654)
2. From contact with his girlfriend. Kissing?
3. Enlarged lymph node in the neck.
4. Infectious mononucleosis results from a “civil war” in which cytotoxic T lymphocytes
kill infected B lymphocytes. This “war” is responsible for the symptoms and signs of
infectious mononucleosis.
5. Care of mono patients involves relief of the symptoms; most patients recover without
treatment within two to four weeks, though infection is permanent when EBV becomes
Emerging Disease Case Study: Babesiosis (p. 655)
1. Upon infection, Babesia microti grows in red blood cells and destroys them. This causes
3. Four pairs
Clinical Case Study: An Opportunistic Infection (p. 662)
1. Physicians diagnose T. gondii infection by serological detection of organisms in tissues,
by microscopic identification of parasites in biopsies, or by molecular identification of
2. Toxoplasmosis.
4. Humans typically become infected by ingesting undercooked meat containing the
parasite. Over 2.4 billion people are infected; at greatest risk are butchers, hunters, and
anyone who tastes food while preparing it. Ingesting or inhaling contaminated soil can
also be a source of infection. The protozoan can also cross a human placenta to infect the
5. Over 80% of infected patients have no symptoms and no obvious permanent damage,
Emerging Disease Case Study: Snail fever in China (p. 663)
1. A part of the life cycle of Schistosoma is in the snail. In freshwater, the eggs hatch,
2. It breaks the connection between humans and snails. Eggs are released in the human who
3. The itching skin represents the area where the larvae burrowed in to the skin.
CHAPTER 22 Microbial Diseases of the Respiratory System
Clinical Case Study: The coughing cousin (p. 689)
1. Marjorie’s last vaccine was at 16 years of age. She needs to get a booster shot of Tdap. It
has a reduced dose of pertussis and diphtheria vaccine and is only meant to be used as a
2. The first stage of whooping cough is the catarrhal (runny nose) stage. This phase
typically lasts for one to two weeks. Symptoms during this phase resemble that of an
upper respiratory illness: runny nose, nasal congestion, sneezing, and occasional cough.
A low-grade fever may be present in some cases. It is only during this stage that
progression of whooping cough can be halted by antibiotics.
4.
Adults 19 years or older who did not receive Tdap as a preteen or teen should also
receive a single dose of Tdap.
5. The six weeks old cousin.
8. By droplets and aerosols during coughing. She should take a booster vaccination. She
Emerging Disease Case Study: H5N1 Influenza (p. 691)
1. Influenza strains are reviewed in February (for the northern hemisphere) and September
(for the southern hemisphere) to detect new immune-escape variants and determine if an
2. There are two species of viruses, designated types A and B, that cause influenza. Each flu
virion is surrounded by a pleomorphic envelope studded with prominent glycoprotein
3. The genomes of flu viruses are extremely variable, especially with respect to the genes
that code for HA and NA. Mutations in the genes coding for these glycoprotein spikes are
responsible for the production of new strains of influenza virus, via processes known as
antigenic drift and antigenic shift.
Clinical Case Study: A Blue Baby (p. 697)
2. Verification of RSV infection is made by immunoassay. Specimens of respiratory fluid
3. Supportive treatment includes administration of oxygen, intravenous fluids, drugs to
reduce fever, and antibiotics to reduce secondary bacterial infections. Immunoglobulins
4. This is not a routine or recommended vaccination. Attempts at developing a vaccine with
5. It is possible that the younger child caught the disease from the older sibling. The older
Emerging Disease Case Study: Pulmonary Blastomycosis
(p. 701)
1. Dimorphic means it has two physical forms or shapes. It is an ascomycete when growing
2. Because the AIDS patient is immunocompromised.
Chapter 23 Microbial Diseases of the Digestive System
Clinical Case Study: When “Health Food” Isn’t (p. 726)
2. Stool specimens are inoculated onto several agar media, including a nonselective
3. It could be Escherichia coli, Campylobacter jejunii or Shigella to name a few of the
possibilities.
4. The woman, had to go to the restroom so many times, for her diarrhea. There was cross
5. Treatment involves replacing lost fluid and electrolytes. Antidiarrheal drugs can prolong
the symptoms by delaying expulsion of the bacterium from the digestive tract. Patients
6. Food preparers should wash their hands thoroughly before touching any food items or
Clinical Case Study: The Case of the Lactovegetarians (p.
727)
1. Most likely Campylobacter jejunii.
3. Campylobacter infections are not contagious. However, they are well advised to maintain
good personal hygiene and wash their hands well during their trips to the restroom.
Emerging Disease Case Study: Norovirus Gastroenteritis (p.
733)
1. Their transmission is via the fecal-oral route from contaminated food or water. The
2. Because these viruses are naked, meaning they have protein capsids, but no phospholipid
3. An infected person, takes the contaminated clothes to be washed at the laundromat – thus
Clinical Case Study: Painful Dysentery (p. 738)
2. Luminal amebiasis, Amebic dysentery, Invasive extraintestinal amebiasis,
3. The least severe form, luminal amebiasis, occurs in otherwise healthy individuals and is
asymptomatic. Invasive amebic dysentery is a more serious form of infection
4. Infection arises following consumption of contaminated water or food, ingestion from
contaminated hands, or during oral-anal inter– course. Cockroaches and houseflies can
5. Treatment involves oral rehydration therapy (vital in severe cases) and antiamebic drugs.
Iodoquinol and paromomycin are effective for asymptomatic infections. Physicians may
prescribe metronidazole followed by iodoquinol for symptomatic amebiasis. Antibacterial
agents may also be prescribed to prevent secondary bacterial infections. Antidiarrheal
Instructor’s Manual for Microbiology with Diseases by Body System, 5e
medications should be avoided because they may worsen the condition by retaining the
organism in the intestinal tract.
CHAPTER 24 Microbial Diseases of the Urinary and Reproductive
Systems
Clinical Case Study: A Painful Problem (p. 763)
2. Sexually transmitted from one of the multiple partners he has had in the previous six
months.
3. Gonorrhea is often asymptomatic in women. Many do not know that they have had the
5. There is no long-term specific immunity against N. gonorrhea, and thus people can con-
tract gonorrhea multiple times. This lack of immunity is explained in part by the highly
Clinical Case Study: A Sick Mother-to–Be (p. 767)
2. The bacterium infects children as they pass through the birth canal. The pathogen may
also be transmitted from eye to eye via droplets, hands, contaminated fomites, or flies.
When babies are infected at birth, an eye disease called trachoma develops. Trachoma is
the leading cause of nontraumatic blindness in humans worldwide.
3. Physicians prescribe doxycycline or erythromycin to eliminate genital infections in
adults. PID is treated with cefoxitin plus doxycycline. Trachoma strains of C.
4. Trachoma strains of C. trachomatis multiply in cells of the conjunctiva, killing them and
triggering a copious, purulent (pus-filled) discharge that causes the conjunctiva to
5. LGV strains of Chlamydia infect the lymph nodes in the groin, producing buboes. In a
few patients, lymphogranuloma venereum proceeds to a third stage characterized by
genital sores, constriction of the urethra, and severe genital swelling. Arthritis may also
Clinical Case Study: A very sick Man (p. 770)
2. Physicians diagnose AIDS on the basis of unexplained weight loss, fatigue, fever, fewer
3. Through breaks in the skin / mucosa.
CHAPTER 26 Microbial Ecology and Microbiomes
Clinical Case Study: Bioterrorism in the mall (p. 816)
1. Category A: Highest Priority