Money, Sex, and Drugs: A Case Study to Teach the Genetics of Antibiotic Resistance

INTRODUCTION

“Ciprofloxacin Resistance in Neisseria gonorrhoeae” was developed to introduce college freshmen without a declared major to important concepts in biology within a real-world context and to increase their content knowledge and critical-thinking skills. The main question driving development of this unit was whether engaging students in answering complex biological questions increased their understanding of biological principles, such as the Central Dogma of molecular biology, mutation, evolution, natural selection, and antibiotic resistance. We used the problem of antibiotic resistance in Neisseria gonorhoeae and the societal questions linked to the epidemiology and treatment of gonorrhea because it requires understanding of fundamental biological concepts and raises issues about money, sex, and drugs, combining biological content with civic engagement.

How antibiotics work is not well understood by the general public. For example, a survey of 7120 adults in the United Kingdom revealed that 38% did not know that antibiotics are ineffective against most coughs and colds, while 43% did not know that “antibiotics can kill the bacteria that normally live on the skin and in the gut” (McNulty et al., 2007). Improving middle school students' and soldiers' understanding of the biology underlying transmission of sexually transmitted diseases (STDs) also improves their ability to identify the risk factors associated with acquiring an STD (Yaren et al., 2004; Zamora et al., 2006). Thus, improved understanding of the biological content covered in this unit is important in addressing a variety of public health concerns.

Improved comprehension of the major themes of biology addressed in “Ciprofloxacin Resistance in Neisseria gonorrhoeae” is also important for general scientific literacy. According to studies by Miller and colleagues, one in three American adults firmly rejects the concept of evolution (Miller et al., 2006), partially based on misconceptions about the theory of evolution and data supporting it. Directly engaging students' misconceptions and prior knowledge has been shown to be important in improving their understanding of commonly misunderstood topics including evolution (Verhey, 2005). The rationale behind having students solve real-world problems to increase their subject matter comprehension and critical-thinking skills is discussed in-depth in The Power of Problem-Based Learning (Duch et al., 2001).

A scientific teaching approach was used to address multiple learning goals (Table 1) and incorporate a variety of activities to engage a diverse student population in learning. The emphasis of the scientific teaching approach is to infuse the classroom with the critical thinking, rigor, and creativity common to experimental research (Handelsman et al., 2007). As part of scientific teaching, we used methods previously shown to improve student learning (reviewed in Handelsman et al., 2004; Handelsman et al., 2007). We supplemented short lectures with active-learning exercises in which students discover knowledge and develop critical-thinking skills. A parallel scientific process was used to plan, assess, and revise the instructional materials (see Chapter 5, Handelsman et al., 2007).

The primary activity for the unit immersed students in a complex and current scientific problem. Students were given a case study in which they must decide how best to address the emergence of ciprofloxacin-resistant gonorrhea. The case crossed several disciplines and stimulated-consideration of scientific, political, and socioeconomic issues. Multiple types of resources were available for the students to solve the case, including research articles, websites, computer animations, and podcasts. (All materials for this unit, including lecture notes, slides, and activities are posted on the Scientific Teaching Digital Library at http://scientificteaching.wisc.edu/materials in the Molecular Biology section.) The case was the cornerstone of the entire unit, in which students learn about the Central Dogma of molecular biology, mutation, evolution, natural selection, and antibiotic resistance. Through active-learning exercises and group problem solving, students were exposed to content information and addressed misconceptions in the field. This article describes construction of the unit using a scientific teaching approach, implementation of the materials in a freshman seminar, evaluation of student learning gains, and discussion of other applications of these materials.

MATERIALS AND METHODS

Course and Student Background

This unit was designed for “Ways of Knowing Biology,” an introduction to biological research for freshmen at the University of Wisconsin (BIO 150, http://wiscinfo.wisc.edu/cels/wok/index.html). The 74 students met once a week for 50 min and were graded on a pass/fail system. The overarching goal of the course is to help freshmen appreciate how the research process contributes to understanding biology.

Topic Selection and Unit Development

Design of this unit was a collaboration among graduate students studying disease mechanisms in Neisseria gonorrhoeae and transcription regulation, science education program coordinators, and professors of genetics, bacteriology, and biochemistry. Additional input was provided by other students developing instructional materials. The process of instructional materials development and the underlying teaching and learning philosophy are described in Scientific Teaching (Handelsman et al., 2007) and Understanding by Design (Wiggins and McTighe, 1998). Once learning objectives for the unit were identified (Table 1), a specific topic was selected and the unit was constructed. Considerations in selecting a topic were: (1) illustration of multiple scientific principles, (2) connection to current research, and (3) interest to students. Ciprofloxacin resistance in N. gonorrhoeae fit these considerations and the research background of the developers. We thought sexually transmitted disease would be a provocative topic that would keep students focused on the learning objectives. The case study was piloted in fall 2004 in a similar introductory biology seminar course for freshmen at the University of Wisconsin, “Exploring Emerging Issues in Genetics.” Other unit aspects were piloted as well through the Wisconsin Program for Scientific Teaching (http://scientificteaching.wisc.edu), including the Gonococcal Isolate Surveillance Project (GISP) problem, the video “A Tiny World,” and the antibiotic resistance misconceptions worksheet (adapted from “Bacteria Really Do Rule!,” Laurieann Casey [http://scientificteaching.wisc.edu/materials], based on a cartoon by Dianne Anderson and Kathleen Fisher [www.biologylessons.sdsu.edu/cartoons/30_antib.pdf]).

Classroom Activities

“Ciprofloxacin Resistance in Neisseria gonorrhoeae” was presented over a 3-wk period (see Table 1). Students were expected to complete research and work as a group outside of class to write a case solution. The class was randomly divided into groups of five to six students who were asked to sit together in the auditorium. Day 1 began by addressing misconceptions about antibiotic resistance. The class watched a video, “A Tiny World,” in which people on the street are asked questions including “Would you take antibiotics for a cold?” and “Why aren't antibiotics as effective today as they once were?” Students then individually completed a worksheet containing the following “correct the statement” exercise:

After working by themselves, students discussed their answers with their groups and reached a consensus. Discussion of the consensus answers served as an introduction to a 20-min mini-lecture on antibiotic functions, the molecular basis of antibiotic resistance, and the Central Dogma of molecular biology. Students' understanding of gene expression was then assessed; the groups were asked to complete an exercise in which they arranged the terms mutation, DNA replication, transcription, and translation in the proper sequential order. Answers were recorded on a sheet of paper and held up for the instructor to view. A second mini-lecture described mutation and natural selection as the basis for the evolution of antibiotic-resistant bacterial strains. After the mini-lecture, the students worked again with their groups to correct the misconceptions they originally identified in the video and on the worksheet and then shared their answers with the class. As homework, the students listened to a podcast interview with Craig Roberts, a Clinical Assistant Professor at University Health Services clinic, that focused on the prevalence of antibiotic-resistant gonorrhea on the University of Wisconsin–Madison campus.

On Day 2, a mini-lecture was presented on mechanisms of ciprofloxacin resistance and symptoms and incidence of gonorrhea. Students wrote short answers to questions posed by the instructor (“At what stage(s) in the flow of genetic information from DNA to RNA to protein does ciprofloxacin act?” and “What is the result of treating bacteria with ciprofloxacin?”) to determine whether they understood how ciprofloxacin functions. Then, they repeated the activity ordering the stages of gene expression from Day 1, but this time the example of a mutation in the gyrA gene (encoding DNA gyrase) and the phenotype of ciprofloxacin resistance was given. Students discussed their answers to both activities with their groups and then the class.

To introduce the case study, each group worked on a problem to detail the limits and biases of the GISP, which is the study protocol the Centers for Disease Control and Prevention (CDC) uses to monitor antibiotic resistance in N. gonorrhoeae (www.cdc.gov/std/gisp/). Students wrote their responses individually, then discussed their ideas with their group and the class. Students noted that the GISP study design excludes women and patients not attending public health clinics in large cities. By determining the problems inherent in the CDC's strategy for monitoring antibiotic-resistant N. gonorrhoeae infections, students gained familiarity with questions they would explore further in the case study.

The centerpiece of the unit was a case study: “You run a public health clinic in Racine, Wisconsin. One of the county commissioners overseeing your clinic is an epidemiologist and wants to know how you plan to address the emergence of ciprofloxacin resistance in Neisseria gonorrhoeae. State budget cuts mean you cannot afford to give all your patients more expensive antibiotics or do all the lab tests you would like. Develop a plan to address the medical, economic, and political questions your clinic will face in dealing with ciprofloxacin-resistant Neisseria gonorrhoeae. Provide scientific data to support your conclusions. Work with your group to describe your clinic plan in a 1- to 2-page, referenced written report.”

Each student group gathered information about antibiotic resistance in N. gonorrhoeae, epidemiology of gonorrhea, and treatment options for the disease. Based on this information, the groups each formulated a plan to address ciprofloxacin resistance in N. gonorrhoeae as if they directed a public health clinic in Wisconsin. Students critically analyzed information to support their proposed testing strategy and to justify its political and socioeconomic impacts. Each group prepared a 1- to 2- page report with their findings, which was evaluated following the rubric in Table 2.

Assessment

Each in-class activity was assessed (Table 1), and group work and contributions to class discussion were informally monitored. The following pre- and postunit survey was conducted anonymously via a web-based survey tool (Zoomerang) to measure student confidence and knowledge with a set of knowledge and skill questions and open-ended course content questions (see also Table 3).

1. What is your declared major? If your major is undecided, what major(s) are you considering?

2. Gender

3. Race

4. Explain how genetic information is transferred from DNA to RNA to proteins. Include the terms: DNA replication, transcription, translation.

5. What could be the consequences to this flow of information if a mistake occurs during DNA replication?

6. Why aren't antibiotics as effective in treating disease as they used to be?

7. Please rate your KNOWLEDGE of the following concepts. (none - 1, very low - 2, low - 3, moderate - 4, high - 5, very high - 6)

   1. The role of bacteria in human health

   2. The role of evolution in disease epidemics and antibiotic resistance

   3. How a change in genotype may perturb phenotype

   4. The flow of genetic information from genes to proteins (gene expression)

   5. The role of oncogenes in human disease

8. Please rate your SKILL in the following areas. (none - 1, very low - 2, low - 3, moderate - 4, high - 5, very high - 6)

   1. Able to work as an effective group member

   2. Able to communicate my ideas logically

   3. Able to solve difficult problems about microbiology

   4. Able to propose hypotheses, analyze data, and draw conclusions

   5. Able to consider ethical and societal dilemmas involved with science and technology

9. Explain a mechanism of antibiotic resistance. Provide an example.

10. Postunit only: What changes would you suggest to improve this unit?

11. Enter your student ID number here

12. Are you age 18 or older?

Students were asked to rate their knowledge of the role of bacteria in human health, and the role of oncogenes in disease, evolution, mutation, and gene expression. A rating of 1 corresponded to no knowledge of the concept, and the top rating of 6 corresponded to a very high level of knowledge about the concept. An identical scale was used to rate their skills in group work, communication, and problem solving. The open-ended questions were scored following the rubric in Table 4 and covered gene expression, mutation, and antibiotic resistance. The response rate was 61% for the preunit survey (n = 45) and 49% for the postunit survey (n = 36). The case study responses were assessed by the rubric in Table 2.

RESULTS

Of the 74 students in the course, 23 completed both the pre- and postunit surveys as determined by matching student ID numbers submitted with each survey. These data were analyzed in paired t tests. Students self-reported learning gains (p ≤ 0.05) in all knowledge categories (Figure 1). Four of these categories (role of bacteria in human health [p < 0.01], role of evolution in disease epidemics and antibiotic resistance [p < 0.001], how a change in genotype may perturb phenotype [p < 0.01], and gene expression [p < 0.01]) aligned with the major learning goals of the unit (Table 3). Knowledge category #5, “the role of oncogenes in human disease,” was not covered in the unit and was included as a negative control. Learning gains were also reported in this category (p < 0.05), but the average knowledge ratings in this category increased from “very low” (preunit survey) to “low” (postunit survey) as compared with ratings of “low” (preunit) and “moderate” (postunit) for the other categories (Figure 1A).

Learning gains were also self-reported in one of the five skill categories, “the ability to solve difficult problems about microbiology” (p < 0.001; Figure 1B). Student ratings for the rest of the skill categories were relatively unchanged through the course of the unit; however, students were more confident in these general communication and group work skills. The average preunit survey rating for these categories was “moderate” or “high” (Figure 1B), leaving little room for improvement. Analyzing all survey data or using the Wilcoxon Signed Ranks Tests to determine significance did not change which gains were statistically significant in any of the questions (data not shown).

The answers to the open-ended questions concerning gene expression, mutation, and antibiotic resistance in the survey were evaluated following the rubric in Table 4. Any unanswered question or “I don't know” answer was rated “needs improvement.” Analysis of these responses did not yield evidence of significant learning gains across the entire sample (data not shown). However, increased understanding was noted in some pairs of matched responses pre- and postunit (Table 5).

The majority of student groups proposed feasible solutions to the case, meeting the outstanding or competent levels in all categories of the rubric (Table 2). Their responses provided additional assessment as all unit learning goals were addressed in the case. The most common solution involved treating low-risk patients with ciprofloxacin and high-risk patients with a more expensive antibiotic to which widespread resistance in N. gonorrhoeae has not been observed. Outstanding student solutions included:

Students presented arguments about the economic, political, and social impacts of their plans. Many felt that funding limitations were forcing them to cut corners in patient care and, in doing so, their plans had to risk missing detection and proper treatment of some cases of ciprofloxacin-resistant gonorrhea. The most often-cited social impact of the plans was the potential for members of high-risk groups to feel discriminated against or stigmatized, and a political concern often mentioned was that funding requests for sexually transmitted disease treatment and safe-sex education could be opposed by proponents of abstinence-only education.

DISCUSSION

Our driving questions in the design of this unit were: “How can we encourage students to engage with each other and the scientific content?” and “Are the students achieving the learning goals?” Students were encouraged to seek, interpret, and synthesize their own information as much as possible. Students were challenged with a complex problem that was most effectively addressed with a collaborative effort. This teaching unit used a variety of instructional formats to appeal to auditory (e.g., Podcast) and visual (e.g., PowerPoint mini-lectures) learners. In addition, the unit incorporated both individual and group work. Students were, for the most part, willing to participate in active-learning activities or work within a randomly assigned group, though some needed instructor encouragement to do so.

Active learning was incorporated throughout the unit. These activities were interspersed among mini-lectures and gave the students opportunity to apply new information to their existing base of knowledge. The active-learning activities emphasized the key concepts of the mini-lectures and directly confronted common misconceptions about antibiotic resistance, gene expression, and evolution (Table 1). For example, to emphasize the concept that “genotype can perturb phenotype,” students conducted a strip sequence exercise in which they arranged the major steps of gene expression into the correct order. A similar exercise was performed with expression of the bacterial gyrA gene and how it relates to the mechanism of the antibiotic ciprofloxacin. Finally, the students determined how the expression of a mutant version of the gyrA gene could result in the phenotype of ciprofloxacin resistance. This activity led into a discussion of the misconception that all mutations cause a change in a protein, alter a phenotype, or are disadvantageous for an organism.

Students self-reported small learning gains in knowledge about oncogenes, the negative control question (Figure 1A). This suggests students may rate their knowledge higher after a learning experience even if the experience did not include the knowledge being assessed. However, their self-assessment of learning gains was higher for knowledge that was included in the unit. The areas in which the most significant gains were reported correspond with the activities presented. During the “What's Wrong with This Statement?” activity, students directly addressed common misconceptions related to the evolution of antibiotic resistance. The “role of evolution in disease epidemics and resistance” displayed the largest learning gain among the knowledge categories. This area was also addressed during the case study activity as students formulated a plan to address the problem of antibiotic-resistant N. gonorrhoeae. Likewise, among the skill categories, students demonstrated significant learning gains in their “ability to solve difficult problems about microbiology” (Figure 1B), which they did during the case study and GISP problem. However, in addition to a tendency to overestimate learning gains, completion of a voluntary survey in a one-credit, pass/fail course may be more likely by those students who really enjoyed the content or style of the unit. We did not offer inducements to complete the survey or penalize students' grades if they chose not to provide a response; safeguards against perceived coercion are part of the human subjects protocol. Thus, not all students participated, but we collected and analyzed 23 pairs of pre-/postunit surveys. Perhaps the return rate would have been higher in an A–F graded course.

Learning gains were not noted uniformly across the sample of student responses to the open-ended questions included in the survey, though some pairs of matched responses did demonstrate a change in comprehension. Nor were all case solutions outstanding in every aspect measured by the rubric. Thus, although some learning gains were made, uniform achievement of the learning goals was not met by all students. Given the complexity of the topics covered and the range of skills demanded, this is hardly surprising.

The unit developed, “Ciprofloxacin Resistance in Neisseria gonorrhoeae,” is adaptable for use in undergraduate discussion or laboratory classes of any level in biology, genetics, microbiology, epidemiology, or public health with few changes. No special equipment is needed for this unit. We provided the students with blank paper and black markers to record their answers to the group activities. However, all activities could be adapted into graded quizzes and worksheets. Instructional technology such as “clickers” could be used for more formalized assessment. The case is open-ended, as are the solutions. For example, the case could be used to model disease transmission in an epidemiology course or to compare methods of strain typing in a molecular biology course. An instructor could also emphasize course-specific content during the discussion without significantly modifying the materials or change the case question to better mirror course content or current events. For example, students could examine which airline passengers to test after a man diagnosed with extremely drug-resistant tuberculosis travels to Europe for his honeymoon. Additional information on the aligning of cases to course goals can be found in the work of Waterman and Stanley (2005).

In 2007, after the unit was developed, the CDC changed its treatment guidelines for gonorrhea. Because of increased spread of ciprofloxacin resistance in N. gonorrhoeae, only cephalosporins are now recommended to treat gonorrhea (del Rio et al., 2007). However, any of the currently recommended antibiotics can be substituted directly into the case as resistance to spectinomycin (Bala et al., 2005; Su et al., 2007), and reduced susceptibility to ceftriaxone (Tanaka et al., 2006) and cefixime (Wang et al., 2003) in N. gonorrhoeae have been reported. Instructors should access the CDC treatment guidelines for gonorrhea each year to obtain the latest updates (www.cdc.gov/std/treatment).

“Ciprofloxacin Resistance in Neisseria gonorrhoeae” has the potential to allow students to expand their understanding of antibiotic resistance, the Central Dogma of molecular biology, and evolution by natural selection through a series of active-learning exercises, embedded assessments, supplemental lectures, podcasts, and readings containing actual experimental data and covering a real-world problem with no one correct answer. Materials for this unit are freely available through the Scientific Teaching Digital Library in the “Molecular Biology” category at http://scientificteaching.wisc.edu/materials and could be adapted to meet learning goals in other courses (Writing the Case, 2003).

Accessing Materials

The supplemental materials mentioned in this article, more information about the materials generated for this case, and information about the scientific teaching approach used to create them can be found at the Scientific Teaching Digital Library at http://scientificteaching.wisc.edu/materials. No registration or password is required to access this site. The library contains the materials mentioned in this paper (categorized as “Molecular Biology”) as well as instructional materials on other concepts in biology.

REFERENCES