,
,
,Learning Microbiology and Infectious
Diseases: Clinical Case Prep for the
USMLE®
Tracey A. H. Taylor, PhD
Associate Professor
Department of Foundational Medical Studies
Oakland University William Beaumont School of Medicine
Rochester, Michigan, USA
Dwayne Baxa, PhD
Assistant Professor
Department of Foundational Medical Studies
Oakland University William Beaumont School of Medicine
Rochester, Michigan, USA
Matthew Sims, MD, PhD
Professor
Department of Internal Medicine
Oakland University William Beaumont School of Medicine
Rochester, Michigan, USA
49 illustrations
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,Contents
Preface ..................................................................................................................................... vii
Case 1 Adult with a Cough of a Long Duration ......................................................... 1
Case 2 Child with a Sore Throat and Red Eyes ........................................................... 7
Case 3 Adult in Respiratory Distress ............................................................................ 11
Case 4 Adolescent with Sore Throat and Malaise ..................................................... 15
Case 5 Toddler with Upper Respiratory Symptoms .................................................. 19
Case 6 Elderly Male with Two Days of Fever, Chills, and Cough ............................ 23
Case 7 Severely Ill Elderly Male in Respiratory Distress........................................... 27
Case 8 Teenager with a Two-Week-Long Cough ....................................................... 31
Case 9 Adult Male with Persistent Cough and Malaise ........................................... 35
Case 10 Infant with Severe Congestion ......................................................................... 39
Case 11 Adult Male with Fever, Myalgias, and Respiratory Distress ....................... 43
Case 12 Adult Male with Fever, Chills, and Night Sweats ......................................... 47
Case 13 Child with Bloody Diarrhea ............................................................................... 51
Case 14 Child with Stomach Pain and Fever ................................................................. 55
Case 15 Outbreak of Diarrheal Illness ............................................................................ 59
Case 16 Hospitalized Adult Female Who Develops Diarrhea.................................... 63
Case 17 HIV-Positive Male with Diarrhea ...................................................................... 67
Case 18 Adult with Jaundice ............................................................................................ 71
Case 19 Adult with Right Upper Quadrant Pain .......................................................... 75
Case 20 Adult Female with Epigastric Pain after Eating ............................................ 79
Case 21 Elderly Female with Fever and Flank Pain...................................................... 83
Case 22 Adult Male with Rash ......................................................................................... 87
Case 23 Young Female with Joint Pain........................................................................... 91
Case 24 Teenager with Syncopy ...................................................................................... 95
Case 25 Adult Male with Painful Penile Ulcers............................................................. 99
Case 26 Adult Male with Back Pain ............................................................................... 103
,Contents
Case 27 Adult Female with Vaginal Discharge .......................................................... 107
Case 28 Adult Male with a Red Eye .............................................................................. 111
Case 29 Adult Female with Lesion on Labia ............................................................... 115
Case 30 Adult Male with Back Pain after Trauma ..................................................... 119
Case 31 Teenage Girl with Expanding Skin Lesion .................................................... 123
Case 32 Adult Male with Foot Ulcer ............................................................................. 127
Case 33 Adult Male with Flu-Like Illness and Rash ................................................... 131
Case 34 Febrile Teenager with Disseminated Rash .................................................. 135
Case 35 Adult Male with Worsening Shortness of Breath ...................................... 139
Case 36 Adult Female with Facial Pain ........................................................................ 143
Case 37 Adult Female with Painful Rash ..................................................................... 147
Case 38 Adult Female with Headache and Confusion .............................................. 151
Case 39 Adult Male with Painful, Swollen Lymph Nodes ........................................ 155
Case 40 Toddler with High Fever and Upper Respiratory Symptoms ................... 159
Case 41 Adult Female with Febrile Illness................................................................... 163
Case 42 Agitated Male with Rapid Progression to Coma ........................................ 167
Case 43 Teenager with Headache and Fever .............................................................. 171
Case 44 Elderly Female with Severe Headache and Nausea ................................... 175
Case 45 Adult Female with Headache and Disorientation ...................................... 179
Case 46 Adult Male with Headache for Several Months.......................................... 183
Case 47 Febrile Teenager with Headache and Neck Stiffness................................. 187
Case 48 Travelers with Acute Febrile Illness ............................................................... 191
Case 49 Newborn with Jaundice ................................................................................... 195
Case 50 Teenager with Pain in Groin ........................................................................... 199
Bibliography ........................................................................................................................... 203
Index ........................................................................................................................................ 219
,Preface
This book is an assortment of clinical cases intended Licensing Examination (COMLEX) of the United States
to advance the learning of microbiology and infec- Step 1 and Step 2. Five choices are provided for every
tious diseases using case studies. Working with cases question, but for each question there is only one best
is the most ideal approach to involve students in the answer.
learning process because: For each question, answers and explanations are
provided on a separate page. This allows students to
• Every case shows a genuine circumstance, very self-test the entire series of questions before revealing
close to those seen in everyday practice. the answers and explanations so that they may com-
• Every case can elicit several problems that must pletely work through the case and receive optimal
be understood and solved. In other words, it is a formative feedback. The explanations include both
problem-based learning process. the reasons why a given answer is correct and why
• Every case not only requires the knowledge of the distractors are wrong. Many questions are related
several disciplines but also the proper utiliza- to the higher levels of Bloom’s taxonomy (e.g., analyz-
tion of the knowledge to explicit clinical cir- ing, applying, or evaluating) rather than being simple
cumstances. recall questions.
For each case, keywords are provided so that stu-
In terms of the organization of the cases, we pur-
dents may search for a particular area of interest.
posefully intermingled bacteriology, virology, mycol-
Lastly, we have provided a bibliography section for
ogy, and parasitology cases in this book, as well as
the students. Students are invited to use those refer-
organ systems. We feel that students will gain a better
ences in case they discover that they require a deeper
understanding of the topics when they consider all
understanding of the material or if they become in-
types of organisms for each case, as will be the case
spired to seek additional information.
when they are considering the diagnosis of real pa-
The rationale for this book is related to the current
tients. The format of each case is as follows:
trends in medical education. Now, it is evident that
• Each case provides relevant clinical information; the mere retention of information provided by
presenting symptoms and relevant duration, books is insufficient for meaningful learning. The
relevant medical history (which may include utilization of information is progressively significant.
vaccinations), relevant family history, relevant A vast array of medical problems is available in the
recent travel, physical examination findings, literature today, but there are few clinical case books
and lab findings. related to microbiology and infectious disease. This
• Images are used to support the cases. Images in- book links clinical cases to the application of basic
clude microscopic images such as Gram stains, knowledge of microbiology, as well as explains the
electron micrographs, wet mounts, and acid- reasons for using specific drugs in real infectious
fast stains, as well as clinical images and skin disease problems, with the goal of promoting
rashes or lesions. critical thinking.
• Each case is followed by a series of five multiple- The main audience of the book is medical school
choice questions. students. This book will aid these students in their
○ In most cases, the first question requires medical school course work, as well as in preparation
the student to identify the most likely caus- for the USMLE and/or COMLEX Step 1 exam. Medical
ative agent. students in years 3 and 4 may also find these cases
○ Other questions address the knowledge of to be helpful when preparing for the USMLE and/or
microbiology and infectious diseases that COMLEX Step 2 exams, shelf exams, and for their clin-
the student needs to assess the case. For ical rotation coursework. In addition, this book is also
example, prevention and precaution mea- useful for students in other medical professions edu-
sures, transmission, mechanism of action cation, including physician assistant students, nursing
of pathogenesis, diagnostic methods, possi- students, and pharmacy students.
ble complications, etc. Clinical medicine is a fast-evolving discipline. The
○ The last question is often related to the authors have referred to reliable sources in order to
pharmacotherapy of the disease. provide information in accordance with currently
accepted standards. However, the authors are aware
The questions are designed to prepare students that in several instances, the information may be con-
for the United States Medical Licensing Examination troversial. We have tried, as much as possible, to avoid
(USMLE) and/or Comprehensive Osteopathic Medical questions addressing controversial issues.
,Preface
This book is meant to be a companion to the microbiology for more in-depth coverage of the
Thieme microbiology question book, thereby giving subject matter.
students more than one option for learning and
studying microbiology. This book is not intended to Tracey A. H. Taylor, PhD
be a substitute for microbiology textbooks. Students Dwayne Baxa, PhD
are strongly advised to consult their textbooks of Matthew Sims, MD, PhD
, Case 1 Adult with a
Cough of a Long
Duration
A 36-year-old male presents to his primary care physician with a cough of 4 weeks duration.
The cough is paroxysmal, and he sometimes vomits after coughing. Two other people with
whom he works have a similar cough. The patient works at a local automobile assembly plant;
he is married with a 2-year-old child; and he has no history of cigarette smoking.
On physical examination, the patient initially appears in no acute distress, then expe-
riences a severe coughing attack, which leaves him weak and out of breath. Examination of
the head, eyes, ears, nose, and throat (HEENT) revealed a small conjunctival hemorrhage on
the left, and several petechiae were noted on the face. Lungs were clear to auscultation. The
remainder of the physical examination was benign.
Laboratory studies were obtained, and the complete blood count (CBC) with differential
showed a white blood cell (WBC) count of 8,000/ul with a normal differential. Posterior–ante-
rior (PA) and lateral chest X-rays were also obtained and found to be normal.
The physician obtains a nasopharyngeal aspirate that was sent to the microbiology lab-
oratory for Gram stain and culture. An organism not typical for oral-pharyngeal flora and
presumed to be the causative pathogen grew on Regan–Lowe agar after overnight incubation
at 37°C. The Gram stain is shown in the following figure. A confirmatory direct fluorescent
antibody (DFA) staining of the organism isolated from the aspirate was also positive.
