A 52-year-old woman with a history of diabetes mellitus and hypertension presents to the Emergency Department with fevers, chills, and abdominal pain. The symptoms began about 1 week ago and have been getting worse. The abdominal pain is associated with nausea and vomiting, and she has not been able to eat. On examination, her temperature is 38.8°C, blood pressure is 104/68 mmHg, heart rate is 94 beats per minute, and respiratory rate is 16 breaths per minute. Her abdominal examination shows right-sided pain to deep palpation, and she has severe right-sided costovertebral angle tenderness. Her laboratory values are shown below.
A urine culture returns positive for E. coli that is sensitive to ceftriaxone and ciprofloxacin. She is treated with IV ceftriaxone, but after 3 days of treatment she continues to be febrile.
What is the most appropriate next step in management?
CT scan with contrast. This patient has pyelonephritis that likely progressed to a renal or perinephric abscess, which is indicated by the persistent fever. Patients with this complication will present with symptoms typical of pyelonephritis (fevers, chills, flank pain, abdominal pain, anorexia, nausea/vomiting), but will continue to be febrile despite treatment with appropriate antibiotics. Most cases of renal/perinephric abscesses are caused by urologic pathogens (e.g., E. coli and other enteric gram-negative bacilli); however, S. aureus is also common and arrives at the kidneys by hematogenous spread. The best diagnostic test is a CT scan of the abdomen with contrast, although a renal ultrasound can also identify many renal/perinephric abscesses. If the abscess is small, it can be observed with antibiotics alone; if the patient does not respond to antibiotics, or if the abscess is large, both antibiotics and drainage are necessary. Antibiotic therapy should always be based on culture and sensitivity data when available; however, empiric therapy for renal/perinephric abscesses is the same as for pyelonephritis. Options include a fluoroquinolone, ceftriaxone, ampicillin-sulbactam, an aminoglycoside, or anti-staphylococcal antibiotics if S. aureus is suspected.
(A) WBC casts do not necessarily indicate acute interstitial nephritis or glomerulonephritis; they may also indicate an upper UTI such as pyelonephritis. Therefore, a renal biopsy is not the next step. (C) Failure to defervesce after treatment with antibiotics raises the concern for a complication of pyelonephritis, such as a renal or perinephric abscess, and therefore further diagnostic workup should be pursued. (D) The organism is sensitive to both antibiotics, so there is no benefit of changing antibiotics.
An 83-year-old woman is hospitalized after an ischemic stroke. On day 2 of her hospitalization, she develops dyspnea. Her vitals show a temperature of 37.8°C, blood pressure of 146/90 mmHg, heart rate of 102 beats per minute, respiratory rate of 26 breaths per minute, and oxygen saturation of 89% on room air. There are diffuse bilateral rales on pulmonary auscultation. She is placed on supplemental oxygen, and a chest x-ray is ordered immediately, which shows bilateral infiltrates.
What is the most likely diagnosis?
Chemical pneumonitis. Patients are at an increased risk of aspiration with the following conditions: neurologic disorders (e.g., stroke), depressed consciousness (e.g., anesthesia), dysfunctions in swallowing or the normal defense barrier (e.g., achalasia, nasogastric tube), supine positioning, and many others. The diagnosis most consistent with the immediate development of dyspnea and hypoxemia is chemical pneumonitis, which occurs as a result of direct airway damage from gastric acid. The chest x-ray will show changes within hours of the aspiration event. Although most cases resolve shortly in a few days, it is not a benign diagnosis; it may progress to ARDS, and it may be fatal, especially in the critically ill. Therapy involves immediate tracheal suctioning and mechanical ventilation if necessary.
(A) Cheyne–Stokes respiration is an abnormal breathing pattern that may occur after a stroke; however, it would not cause hypoxemia with infiltrates on chest x-ray. (B) Many cases of aspiration will produce both chemical pneumonitis and pneumonia due to inhalation of oropharyngeal microbes; however, it takes days for the pneumonia to become symptomatic (and even longer if it is an anaerobic infection). Many physicians choose to place the patient on empiric antibiotics and discontinue them if the patient’s chest x-ray is clear after 2 to 3 days. (C) An airway obstruction may occur after an aspiration event due to aspiration of particulate matter from the stomach. Without chemical pneumonitis, it would not produce chest x-ray infiltrates.
A 30-year-old man presents to his physician with a rash on his left leg. He reports that the rash started as a bug bite and is spreading. He denies any fever, chills, or malaise. His medical history is significant for type 1 diabetes mellitus, and his only medication is insulin. On examination of the left leg, there is a 4-cm area of erythema, swelling, and warmth with indistinct margins. There is no gross purulence.
What antibiotic should this patient receive?
Oral clindamycin. This is a straightforward case of cellulitis, which is typically caused by Streptococcus pyogenes or Staphylococcus aureus. Patients with risk factors for MRSA (previous MRSA infection or colonization, diabetes, HIV infection, recent hospitalization or antibiotics, IV drug use, etc.) or with gross purulence should receive an antibiotic that has MRSA coverage. Therapy is usually empiric (since skin cultures are rarely helpful) and is based on the clinical diagnosis and patient’s risk factors. (A, B) Cephalexin and dicloxacillin are both appropriate antibiotics if MRSA was not a concern. (D) Although vancomycin has activity against MRSA, this patient has a localized infection without systemic symptoms and therefore can be treated as an outpatient with oral therapy.
For the sake of the shelf examination, there are a few other important soft tissue infections to know. Erysipelas is a more superficial infection of the dermis and is raised with distinct margins. The majority of cases are due to group A strep. Necrotizing fasciitis is caused by virulent strains of group A strep or MRSA and presents with a rapidly expanding lesion that is severely painful and may have crepitation. Treatment is with debridement and antibiotics to cover group A strep and MRSA (e.g., penicillin and clindamycin) unless the history and risk factors suggest an alternative pathogen. Gas gangrene is a life-threatening infection caused by Clostridium perfringens that spreads rapidly with necrosis and significant crepitus; treatment is with debridement and antibiotics (also penicillin and clindamycin). If the patient has a penetrating injury (e.g., diabetic patient that stepped on a nail that penetrated his shoe), consider Pseudomonas. In gardeners, consider Sporothrix schenckii, which spreads via lymphatics and causes ulcerating nodules. If there is exposure to saltwater, consider Vibrio vulnificus.
A 32-year-old man complains of fever, diarrhea, and abdominal pain. He has had intermittent fevers for the past month, with episodes of bloody diarrhea. The abdominal pain started 2 weeks ago, and since that time he has had fewer episodes of diarrhea. He denies any jaundice, pale stools, or IV drug use. The patient emigrated from Mexico 6 months ago, and has been living with his extended family in Arizona. On examination, there is hepatomegaly with tenderness to palpation over the liver. An abdominal ultrasound reveals a welldefined hypoechoic mass.
What is the most likely pathogen responsible for this patient’s symptoms?
Entamoeba histolytica. Most infections due to the parasite Entamoeba histolytica are asymptomatic; however, this pathogen can cause invasive colitis presenting as dysentery. A common extraintestinal manifestation is liver abscess, which presents with fever and right upper quadrant abdominal pain. This patient recently emigrated from an endemic country and has suggestive symptoms of amebiasis complicated by a liver abscess. Diagnosis can be made with abdominal imaging and stool studies, and treatment is with both metronidazole and paromomycin (to eliminate luminal cysts). Amebic liver abscesses do not need to be drained and are usually treated successfully with medical therapy alone.
(B, E) Streptococcal species, S. aureus, Candida, and Klebsiella are all causes of liver abscess; however, the presentation of dysentery and recent immigration make amebiasis more likely. Escherichia coli, Campylobacter, and Salmonella can all cause invasive diarrhea but are not associated with liver abscesses. Of note, Salmonella can cause hepatosplenomegaly and also establish itself in a chronic carrier state in the gallbladder; however, this patient does not have other features of typhoid fever (“rose spot” rash, relative bradycardia, etc.). Diphyllobothrium latum is a tapeworm that produces GI symptoms and can present with megaloblastic anemia (due to parasitic absorption of dietary vitamin B12). Coccidioides is common in Arizona, but produces pulmonary symptoms; when it disseminates, it typically disseminates to the skin, meninges, or bone.
A 42-year-old man presents to his physician with fever, headache, and rash. Three days ago, he developed fever and a headache, which minimally improved with acetaminophen. This morning he noticed a rash on his wrists and ankles that spread to his torso. He has no past medical history and does not smoke. He recently returned from a camping trip in Virginia 1 week ago. On examination, he is febrile and there are scattered erythematous blanching macules over his arms, legs, and torso.
What should be done next in the management of this patient?
Administer doxycycline. Rocky Mountain spotted fever is caused by the bacterial species Rickettsia rickettsii, which is carried by the Dermacentor variabilis tick. Though infection may occur in many areas of the United States, it is most common in the Southeastern United States. The incubation period is typically around 1 week, after which nonspecific symptoms of fever, headache, and myalgias develop. A few days later, a maculopapular rash appears that starts on the wrists and ankles (also commonly affects the palms and soles) and spreads to the trunk; it often evolves into a petechial rash. There is a high morbidity and mortality of this infection if it goes untreated, therefore doxycycline should be given empirically if the disease is suspected. (C) Testing for serum antibodies to Rickettsia will not be positive until about a week, which is too late; therefore, the diagnosis is usually confirmed with skin biopsy. (B) Rickettsiae infect the vascular endothelium, causing vascular damage and petechiae that may mimic a vasculitis; however, the recent travel and time course of the illness should lead the reader to suspect this infection and treat empirically with doxycycline. (D) Penicillin G is the treatment for syphilis, which can present with a maculopapular rash affecting the palms and soles (secondary syphilis). The patient’s recent hiking trip in Virginia makes infection with Rickettsia more likely. (E) Topical clobetasol is a powerful corticosteroid that may be used in cases of contact dermatitis, which can vary in appearance but often cause a vesicular eruption without systemic symptoms. (Note: Other important cases of a rash affecting the palms and soles include secondary syphilis and coxsackie virus; there are others, but these are the most commonly tested.)
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