A 72-year-old woman is admitted to the hospital for an acute exacerbation of heart failure. She has a history of congestive heart failure (CHF), hypertension, and diabetes. While in the hospital, she is diuresed with IV furosemide and her symptoms improve. However, 3 days later she develops worsening shortness of breath. Her temperature is 38.1°C, blood pressure is 104/68 mmHg, heart rate is 94 beats per minute, respiratory rate is 26 breaths per minute, and oxygen saturation is 92% on room air. A chest x-ray is ordered and is shown in Figure below:
What is the most appropriate empiric treatment?
Ceftriaxone, levofloxacin, and vancomycin. In a patient with pneumonia, it is important to first define the type of pneumonia since this identifies the likely organism and the necessary empiric antibiotic therapy. Hospital-acquired pneumonia (HAP) refers to the development of pneumonia >48 hours after admission, with no evidence of pneumonia on admission. A type of HAP is ventilator-associated pneumonia (VAP), which occurs 48 to 72 hours after mechanical ventilation.
Common Etiologies of Pneumonia and Empiric Antibiotic Regimens:
Healthcare-associated pneumonia (HCAP) develops in a patient with recent or ongoing contact with healthcare facilities or personnel (e.g., hospitalized ≥2 days in the last 90 days, lives in a long-term care facility, receives dialysis, etc.). Finally, community-acquired pneumonia (CAP) refers to pneumonia that develops in all other patients. Table 6-1 shows the common organisms causing each type of pneumonia as well as the appropriate empiric antibiotic therapy
(A) Empiric antibiotics for inpatient CAP consist of an anti-pneumococcal β-lactam (e.g., ampicillin-sulbactam, ceftriaxone, cefotaxime, ceftaroline, ertapenem) and a macrolide (e.g., azithromycin or clarithromycin). An alternative is a respiratory fluoroquinolone alone (e.g., levofloxacin, moxifloxacin). (C) Clindamycin is a good agent to use for suspected aspiration pneumonia and may be used as monotherapy. (D) This answer would be correct if the patient’s heart failure symptoms were not improving; however, the presence of fever and consolidation on chest x-ray indicate pneumonia.
A 29-year-old woman presents to the hospital with fever, headache, and cough. She developed these symptoms 2 days ago, and now also endorses some shortness of breath. She denies any rash, neck stiffness, recent travel, or sick contacts, and she has received all of her immunizations including her annual influenza vaccine. She lives in Connecticut and has several dogs. She is febrile to 38.7°C, but the rest of her examination is unremarkable. Her laboratory values are shown below:
Which of the following is the most likely causative organism?
Ehrlichia chaffeensis. Nonspecific flu-like symptoms associated with leukopenia, thrombocytopenia, transaminitis, anemia, and an elevated creatinine are strongly suggestive of ehrlichiosis/anaplasmosis. Ehrlichia chaffeensis is carried by the Dermacentor variabilis tick (which can also carry Rickettsia rickettsii) or the Amblyomma americanum tick and causes human monocytic ehrlichiosis; Anaplasma phagocytophilum is carried by the Ixodes tick (which may also carry Borrelia burgdorferi and Babesia microti, and coinfection can occur), and causes human granulocytic anaplasmosis. Both are gramnegative obligate intracellular bacteria that can produce the above clinical findings, and therefore they are often described together. The diagnosis is typically made with PCR, since the finding of intraleukocytic morulae on peripheral blood smear may be seen but is not a sensitive test. Treatment is with doxycycline. Although many of the other answer choices can produce the nonspecific symptoms seen in this patient, the laboratory abnormalities point to the diagnosis of E. chaffeensis/A. phagocytophilum infection. (A, E) These answer choices are other important tick-borne illnesses. B. burgdorferi causes Lyme disease, which presents with the rash of erythema migrans. F. tularensis can occur through contact with ticks or animal tissues and will produce a necrotic eschar at the site of infection and lymphadenopathy. B. microti can cause a severe hemolytic anemia, and a peripheral blood smear shows the parasite within red blood cells (RBCs). R. rickettsii causes Rocky Mountain spotted fever, which presents with a rash that starts peripherally and spreads centrally. (C) This patient had her annual influenza vaccine (though not 100% protective), and influenza would not produce the laboratory abnormalities seen in this patient. (E) S. pneumoniae is the most common cause of CAP and meningitis. (D) Yersinia pestis is carried by fleas and causes bubonic, pneumonic, or septicemic plague. Neisseria meningitidis is a cause of meningitis and sepsis; the incidence has decreased since the introduction of the meningococcal vaccine. Parvovirus B19 produces erythema infectiosum (fifth disease with the classic “slapped cheek” rash) in children, but in adults can produce arthralgias, aplastic crisis in patients with chronic hemolytic disease, miscarriage in pregnant patients, and chronic pure RBC aplasia in immunocompromised patients.
A 42-year-old man is brought to the hospital by his wife due to headache and a change in mental status. His wife reports that the symptoms started yesterday and are getting worse. He has experienced migraines previously, but the pain and photophobia are much worse this time. He was not himself and was very confused this morning, so she brought him to the Emergency Department. His temperature is 38.8°C with a normal blood pressure and heart rate. There is moderate neck stiffness on examination with no focal neurologic deficits. A lumbar puncture is performed, and a Gram stain of the cerebrospinal fluid (CSF) shows gram-positive cocci.
What is the most likely pathogen, and what would be expected on CSF analysis? (Note: WBCs are white blood cells.)
: S. pneumoniae, ↑ WBCs, ↑ protein, ↓ glucose. The Gram stain confirms that this patient has acute bacterial meningitis, which commonly presents with fever, headache, neck stiffness, and/or mental status changes. Other symptoms include photosensitivity and seizures. The most common causative organism is S. pneumoniae, which is a lancet-shaped diplococcus. Other common pathogens that cause meningitis are summarized in Figure below.
The CSF findings in meningitis are high yield for the shelf examination. Bacterial meningitis will present with very elevated lymphocytes with a neutrophil predominance, low glucose, and elevated protein. Viral meningitis will present with elevated lymphocytes with a lymphocyte predominance (though there is often a neutrophil predominance early in the course of the infection), normal glucose, and mildly elevated protein. Fungal meningitis will have findings similar to viral meningitis, except that the glucose will be low. Meningitis due to tuberculosis (TB) will have findings similar to fungal meningitis, but other clues will be given to help make the diagnosis such as exposures, risk factors, and acid-fast bacilli (AFB) smear or culture.
A 26-year-old man presents to his primary care physician complaining of fatigue, headache, and a sore throat for the past week. There is also nausea and diarrhea, but no weight loss, productive cough, or difficulty breathing. He denies any past medical history, does not take any medications, and has no recent sick contacts. He is sexually active with men and women and uses condoms inconsistently; he drinks alcohol heavily on the weekends and admits to previous IV drug use. On examination, his temperature is 39°C and the rest of his vital signs are normal. He has nontender cervical and axillary lymphadenopathy, tonsillar exudates, and mild splenomegaly. There are also several painful, well-demarcated ulcers within his mouth and a mild maculopapular rash over his chest and arms. A rapid strep test and a monospot (heterophile antibody) test are negative; further screening for chlamydia, gonorrhea, syphilis, and HIV is negative.
What is the most likely diagnosis?
Acute retroviral syndrome. Acute HIV infection can present in a variety of ways, but typical symptoms of the “acute retroviral syndrome” include a mononucleosis-like syndrome with fever, lymphadenopathy, headache, myalgias/arthralgias, sore throat, and a maculopapular rash. Another less sensitive but more specific finding is painful, well-demarcated mucocutaneous ulcerations. Additional clues to the diagnosis in this case are the patient’s high risk behaviors (unprotected sex, IV drug use) and negative test results for other conditions on the differential diagnosis (mononucleosis due to EBV, syphilis and other STIs, etc.). During the acute phase of HIV infection, there may be a negative screening test (ELISA may take weeks to become positive) with high viral RNA levels. Typically, the diagnosis of HIV is made with a highly sensitive screening test (e.g., ELISA) followed by a more specific confirmatory test (e.g., Western blot).
(A) The finding of diffuse nontender lymphadenopathy is more consistent with a systemic process such as a viral infection rather than Hodgkin lymphoma, which often presents with focal or asymmetric lymphadenopathy. (C) Though heterophile-negative mononucleosis due to CMV is a possibility, the findings of both maculopapular rash and mucocutaneous ulcerations make HIV more likely (both may occur in CMV infection but are less common manifestations, and GI ulcerations usually occur in the setting of immunosuppression). (D) Secondary syphilis is less likely to have mucocutaneous ulcerations and the screening test was negative. Although false negatives are possible with RPR and VDRL tests, the constellation of findings makes HIV infection much more likely than a false-negative syphilis test.
A 65-year-old man is brought into the Emergency Department by his daughter, who reports that he is fatigued and short of breath. Several days ago he developed a fever with a productive cough, which has now progressed to dyspnea at rest. On examination, the patient’s temperature is 38.6°C, his blood pressure is 74/42 mmHg, his heart rate is 96 beats per minute, his respiratory rate is 24 breaths per minute, and his oxygen saturation is 94% on room air. He is lethargic, his neck veins are flat, and his extremities are warm and moist. There is dullness to percussion and decreased breath sounds over the right lung base. Serum blood work shows an elevated lactate.
What is the correct diagnosis?
Severe sepsis. This patient has severe sepsis secondary to pneumonia. It is important to know the definitions related to the topic of sepsis. Systemic inflammatory response syndrome (SIRS) is defined by two or more of the following: (1) temperature >38°C or <36°C; (2) a heart rate >90 beats per minute; (3) a respiratory rate >20 breaths per minute or a PaCO2 <32 mmHg; and (4) a serum leukocyte count >12,000/mm3 or <4,000/mm3 or >10% bands. With a suspected source of infection, it is called sepsis. Severe sepsis is the definition for sepsis with end-organ dysfunction, signified by hypotension or hypoperfusion (e.g., oliguria, elevated serum lactate, elevated liver enzymes, etc.). Septic shock is severe sepsis that does not respond to adequate fluid resuscitation. This patient meets SIRS criteria with a suspected source of infection (pneumonia) and hypotension; (C) IV fluids have not been administered yet, so the definition of septic shock is not met.
Septic shock is one type of distributive shock, which is characterized by hypotension with flat neck veins and warm extremities (low systemic vascular resistance). (E) Anaphylaxis is another form of distributive shock, but is unlikely since there was no history of recent exposures mentioned in the vignette (e.g., bee sting, new medication, etc.). (A, B) Both cardiogenic shock and pulmonary embolism (a type of obstructive shock) are ruled out by flat neck veins (which indicate hypovolemic or distributive shock).Finally, hypovolemic shock would present with flat neck veins and cool extremities, since systemic vascular resistance increases in an attempt to maintain blood pressure.
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