WBR0061
| Author | PageAuthor::William J Gibson (Reviewed by Yazan Daaboul) |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology |
| Sub Category | SubCategory::Reproductive, SubCategory::General Principles, SubCategory::Infectious Disease |
| Prompt | [[Prompt::A 29-year-old sexually active woman presents to the emergency department (ED) with an acute onset of left lower quadrant abdominal pain and chills. She describes the pain as constant and is exacerbated by movement. Her last menstrual period was 8 weeks ago. Her past medical history is significant for tension-type headaches and GERD. Her medications include PRN acetaminophen and daily omeprazole. She denies use of alcohol, illicit drugs, or smoking. Her blood pressure is 118/84 mmHg, heart rate is 92/min, and temperature is 99.7°F (36.7°C). Physical examination is remarkable for left lower quadrant abdominal tenderness with no guarding or rebound tenderness. An initial blood test is immediately sent for analysis; and results are pending. Ultrasound in the ED demonstrates a left adnexal mass. Which of the following organisms most likely predisposed this patient to her current presentation?]] |
| Answer A | AnswerA::Gram-positive, catalase-positive coccus |
| Answer A Explanation | [[AnswerAExp::This describes Staphylococcus aureus, which is responsible for cutaneous infections, particularly staph scalded skin syndrome (SSSS), cellulitis, and bullous impetigo.]] |
| Answer B | AnswerB::Dimorphic fungus |
| Answer B Explanation | [[AnswerBExp::This describes Candida albicans, which is responsible for yeast infections.]] |
| Answer C | AnswerC::Gram-negative, maltose-fermenting diplococci |
| Answer C Explanation | [[AnswerCExp::This describes Neisseria meningitidis, which is responsible for bacterial meningitis in older adults]] |
| Answer D | AnswerD::Gram-positive, catalase-negative coccus |
| Answer D Explanation | [[AnswerDExp::This describes Streptococcus pneumoniae, which is the most common cause of community acquired pneumonia (CAP)]] |
| Answer E | AnswerE::Gram-negative, maltose-nonfermenting diplococci |
| Answer E Explanation | [[AnswerEExp::A common cause of pelvic inflammatory disease (PID) is Neisseria gonorrhea, a gram-negative, maltose-nonfermenting rod.]] |
| Right Answer | RightAnswer::E |
| Explanation | [[Explanation::The patient in this vignette is presenting with a history consistent with ectopic pregnancy. Ectopic pregnancy occurs when an egg is fertilized but implants outside of the uterus, most commonly in the fallopian tube. These pregnancies are not viable, but represent a significant health risk to patients. Early on, ectopic pregnancies can present with pain in the lower abdomen or upon micturition with or without low grade fever. Sometimes mild vaginal bleeding episodes can occur due to poor progesterone production by the corpus luteum and therefore withdrawal of the uterine lining. However, late ectopic pregnancies almost always present with significant pain with either vaginal or internal bleeding. They may also be complicated by peritonitis, marked by high-grade fever, excruciating abdominal pain, with rebound tenderness and guarding on abdominal physical exam.
One of the main risk factors for ectopic pregnancy is pelvic inflammatory disease (PID). PID causes salpingitis, defined as inflammation of the fallopian tubes, which can lead to scarring if untreated. The scarring of the fallopian tube serves as a nidus for inappropriate implantation of the embryo. The most common cause of PID is untreated infection with either Neisseria gonorrhea, (65% of cases) or Chlamydia trachomatis (10% of cases). Patients may be remain asymptomatic despite presence of either/both organisms. Neisseria gonorrhea is a gram-negative maltose-nonfermenting rod which can be treated with ceftriaxone. Due to high prevalence of N. gonorrhea and C. trachomatis co-infection, patients with N. gonorrhea are often also treated with presumable C. trachomatis co-infection with doxycycline. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Pregnancy, WBRKeyword::Ectopic pregnancy, WBRKeyword::Microbiology, WBRKeyword::Bacteria, WBRKeyword::Infection, WBRKeyword::Abdominal pain, WBRKeyword::Pelvic inflammatory disease |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |