LL . Central line‐associated bloodstream infection prevention. Curr Opin Infect Dis. 2012; 25(4):412–422. doi:10.1097/QCO.0b013e328355e4daLatif A, Halim MS, Pronovost PJ . Eliminating infections in the ICU: CLABSI. Curr Infect Dis Rep. 2015; 17(7). doi:10.1007/s11908‐015‐0491‐8Noto MJ, Domenico HJ, Byrne DW, et al. Chlorhexidine bathing and health care‐associated infections: a randomized clinical trial. JAMA ‐ J Am Med Assoc. 2015; 313(4):369–378. doi:10.1001/jama.2014.1840017 A 63‐year‐old female with type II diabetes and a recent HbA1c of 9.4 presents to the ED after she noted a foul odor emanating from the sole of her foot. Upon inspection of her foot, she noticed a large ulcer with surrounding erythema and purulence in the wound bed and presented to the ED. Upon evaluation in the ED, her WBC is 14.4 and she is afebrile. She denies being hospitalized or having a wound like this before.Next steps in care for this patient include:Immediate culture of wound, initiation of meropenem, MRI of the footImmediate culture of wound, initiation of vancomycin and piperacillin/tazobactam, MRI of the footCleansing and debridement of the wound followed by culture of the wound, initiation of ertapenem, MRI of the footCleansing and debridement of the wound followed by culture of the wound, initiation of ertapenem, x‐ray of the footImmediate initiation of vancomycin/piperacillin/tazobactam, debridement and culture of the wound, x‐ray of the foot. This patient has a diabetic foot infection and the wound should be evaluated and treated. Prior to antibiotic administration, the wound should be cleansed and debrided with the deep tissue from the wound sent for culture. Failure to do this can lead to the culturing of skin flora that may not be responsible for the infection. The wound should then be classified, and a probe‐to‐bone test can be used to help in making this decision. There are multiple ways to classify diabetic foot infections; two of the most frequently used classifications are mentioned below.Following an adequate culture and classification of the wound, an antibiotic regimen can be started. This wound would be classified as a moderate diabetic foot infection and therefore should be treated with antibiotics. In a moderate diabetic foot infection, aerobic GPCs, MSSA, Streptococcus spp., Enterobacteriaceae, and other obligate anaerobes are the likely pathogens. These are all adequately covered by ertapenem. Initiation of vancomycin and piperacillin/tazobactam would be a correct answer if this patient had a severe diabetic foot infection. She does not require any further coverage for MRSA or pseudomonal infections as she does not have any current risk factors, nor is her illness severe enough to prompt broad‐spectrum empiric antibiotic coverage.Initial imaging of a diabetic foot infection should always be an x‐ray of the foot, which is both sensitive and specific for osteomyelitis. If any diagnostic uncertainty remains following the x‐ray, an MRI can be pursued.Answer: DLipsky BA., Berendt AR, Cornia PB, et al. 2012 Infectious Diseases Society of America Clinical Practice Guideline for the Diagnosis and Treatment of Diabetic Foot Infections, Clin Infect Dis. 2012; 54 12: e132–e173, https://doi.org/10.1093/cid/cis346
18 A 67‐year‐old male who has returned 6 weeks ago from a trip to New England where he had been trail‐running in preparation from a marathon presents to the ED complaining of intractable fatigue, dark‐reddish urine, and frequent high fevers at home. He reveals that he had pulled a small bug off his arm during his trip and that he did not notice any associated rash. He has splenomegaly on physical exam. His labs return showing a normocytic anemia with elevated transaminases. A Wright’s/Giemsa stain of his peripheral blood demonstrates darkly stained rings with light blue cytoplasm within erythrocytes. The most likely disease responsible for his condition is:Lyme diseaseBabesiosisRocky Mountain Spotted FeverEhrlichiosisAnaplasmosisThis patient has babesiosis, more specifically an infection with the parasite Babesia microti. B. microti is an intraerythrocytic parasite that is transmitted from ticks to vertebrates including humans. The disease contracted by the host can be broad with varying symptoms ranging from asymptomatic infection to a disease like malaria with severe hemolysis and death. Symptoms can take months after exposure to develop. Common signs and symptoms of babesiosis are fatigue, anemia, fevers, chills, night sweats, hemoglobinuria, transaminitis, weight loss, hepato/splenomegaly. Diagnosis is typically made with exposure to ticks, stained blood smears, and ELISA/PCR. The standard treatment for babesiosis is clindamycin and quinine. In a serious infection where clindamycin and quinine are not sufficient, there has been some benefit shown in erythrocyte exchange transfusion.Lyme disease is the most common tick‐borne illness in the United States and is also hosted by the Ixodes tick. It is known for its characteristic bull’s‐eye rash (erythema migrans), but this is not present in all cases. Lyme disease commonly presents with low‐grade fevers and myalgias. The disease, however, can disseminate and affect the musculoskeletal, neurologic, and cardiovascular system. Most commonly, musculoskeletal symptoms are present in Lyme disease in the form of migratory joint and muscle pain. Anemia is not associated with Lyme disease, and this spirochete bacterium is not apparent on a peripheral blood smear. Treatment for Lyme disease is typically doxycycline for adults and amoxicillin for children.Rocky Mountain Spotted Fever is a serious disease that is caused by Rickettsia rickettsii and transmitted after a tick bite. It is most common in the southeastern and south‐central United States. This bacterium preferentially infects the vascular endothelial cells of small and medium vessels in the body. Patients typically present 4–10 days post exposure and have fever, headache, and a rash. Typically, patients are treated empirically based on their history and physical with doxycycline, but PCR can be performed to confirm diagnosis.Ehrlichiosis is a tick‐borne disease carried by the Lone Star Tick found in the south‐central United States. Ehrlichiosis is associated with fever, headache, body aches, malaise, and chills but can include gastrointestinal symptoms, respiratory symptoms, and rash. Associated laboratory findings include leukopenia, thrombocytopenia, hyponatremia, and moderately elevated transaminases. Diagnosis is made clinically or by PCR. Treatment is doxycycline.Anaplasmosis is transmitted by the Ixodes tick and is found worldwide; it is caused by Anaplasma phagocytophilum – an obligate intracellular bacterium. Symptoms include fever, malaise, myalgias, and headache with some patients experiencing nausea, vomiting, diarrhea, cough, arthralgias, and confusion. Rash is uncommon in anaplasmosis. Anaplasmosis is visible on peripheral blood smear, and it can be seen within the neutrophils in aggregates called morulae. Doxycycline is the first line treatment for anaplasmosis.Answer: BGuzman N, Yarrarapu SNS, Beidas SO. . Anaplasma Phagocytophilum. [Updated 2021 Jan 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513341/Homer MJ, Aguilar‐Delfin I, Telford SR III, et al. Babesiosis. Clin Microbiol Rev. 2000; 13(3):451–69. doi: 10.1128/cmr.13.3.451‐469.2000. PMID: 10885987; PMCID: PMC88943.Snowden J, Simonsen KA, Rickettsiae Rickettsia. [Updated 2020 Nov 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430881/Snowden J, Bartman M, Kong EL, et al. Ehrlichiosis. [Updated 2020 Sep 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441966/Bratton RL, Whiteside JW, Hovan MJ, et al. Diagnosis and treatment of Lyme disease. Mayo Clin Proc. 2008; 83(5):566–71. doi: 10.4065/83.5.566. PMID: 18452688
10 Pharmacology and Antibiotics
Michelle Strong, MD, PhD1 and Elaine Cleveland, MD2
1 Trauma and Acute Care Surgeon, Austin, TX, USA
2 William Beaumont Army Medical Center, El Paso, TX, USA
1 A 64‐year‐old man with a past medical history notable of hypertension, hyperlipidemia, peripheral vascular disease, and diabetes
