key: cord-0037716-qsii37yq authors: Varon, Joseph title: Infectious Diseases date: 2016-06-03 journal: Handbook of Critical and Intensive Care Medicine DOI: 10.1007/978-3-319-31605-5_8 sha: 5daa31250c46e191a8ba5da09f592731b7f3c245 doc_id: 37716 cord_uid: qsii37yq As infectious diseases are very commonly seen in the ICU, this chapter covers both typical and atypical infections found in this setting. If the patient has been transferred to the ICU after a prolonged stay in the hospital, the treatment should be focused on a nosocomial infection. This chapter emphasizes that the first thing to do is to identify the organisms causing the patients’ infection, keeping in mind frequently found organisms. Pneumonia, severe adult respiratory syndrome (SARS), sepsis, toxic shock syndrome, and infections in patients with AIDS are among the most common infectious diseases treated in the ICU. An appropriate initial empiric therapy and correct treatment once cultures and susceptibility become available are crucial for a successful treatment. 3. Antibiotics: Broad-spectrum agents will rapidly change normal flora of the mouth and gastrointestinal (GI) tract. 4. Surgery: Especially thoracic, abdominal, or neurosurgery, which increases the risk of aspiration. 5. Chronic lung disease. 6 . Advanced age. 7 . Immunosuppression. C. Etiologic Agents 1. Common -Gram-negative bacteria such as Klebsiella sp., Escherichia coli, Pseudomonas aeruginosa, Enterobacter sp., and Acinetobacter sp. Another helpful approach is to consider the likely pathogens according to the time after hospitalization the pneumonia developed. Late-onset pneumonia (after more than 5 days of hospitalization) is usually characterized with more resistant organisms. D. Clinical Manifestations. Patients in the ICU, especially those who are intubated or sedated, will not manifest the usual symptoms of pneumonia such as cough, chest pain, or dyspnea. Patients who are neutropenic cannot mount an inflammatory response, and, therefore, the sputum will not show purulent material. Subtle changes in oxygenation, fever, and clinical deterioration are clues for the diagnosis of pneumonia in intubated patients. Leukocytosis or leukopenia can be the first manifestation of occult pneumonia. In some instances, i.e., Pneumocystis pneumonia, the presence of spontaneous pneumothorax can be the first indication of pulmonary involvement. Thick, foul-smelling sputum is characteristic of anaerobic and aspiration pneumonia. Duration of therapy is not well defined, but most authors agree on treating gram-negative and anaerobic pneumonia for 10-21 days. Gram-positive processes are usually treated between 10 and 14 days, and atypical pneumonias receive 2 weeks of antimicrobial therapy. Candida pneumonia requires prolonged treatment with up to 1.5 g of amphotericin B as a total dose. Term given by the World Health Organization which describes a rapidly progressive respiratory illness with documented outbreaks in China, Hong Kong, Vietnam, Singapore, and Canada. The presumable pathogen is a Coronavirus that spreads person to person via droplets, sewage, and water and potentially through human feces. It is hypothesized that bats are the primary reservoir for the disease. The mortality rate from SARS is high (up to 20 %). In severe cases, respiratory function may worsen during the second week of illness and progress to ARDS. This is a two-stage illness: 1. Prodrome (2-7 day): Includes fever, malaise, headache, and myalgias, and diarrhea may occur 2. Respiratory phase (8-12 day): Nonproductive cough and dyspnea that rapidly progress to respiratory failure A rapid diagnosis of SARS can be made by reverse transcriptase PCR of respiratory tract, samples, and plasma early in illness. There is no current treatment available for this illness, except for supportive care in the intensive care unit. Preventive measures against SARS are mainly focused on travel advisories to countries and cities with active outbreaks. Efforts are underway to prepare a vaccine for the prevention of SARS. A. More than 750,000 cases of sepsis, with an associated mortality of 20-60 %, are estimated to occur annually. Despite improvements in antimicrobial therapy and supportive care, the incidence of and mortality associated with sepsis have not declined. This is, in part, a consequence of an array of medical advances that can place patients at increased risk for development of infection and, potentially, sepsis. E. Prognosis. Mortality in sepsis is a function of the severity of physiologic derangements, the duration of illness, and the number of organ system failures. These organ systems include, but are not limited to, the lungs, kidneys, and liver. When the pulmonary system becomes dysfunctional, the resultant clinical entity is known as the adult respiratory distress syndrome (ARDS). The sequence has been termed the multiple organ dysfunction syndrome (MODS). MODS is the most common cause of demise in patients who experience uncontrolled inflammation and infection. A. Clinical Case Definition (See Table 8 .1) 1. Severe febrile (38.9 °C) illness with rash (erythroderma followed by desquamation), hypotension or syncope, and multiple organ system involvement (at least four of the following: mucous membrane, GI, muscular, A. Acute meningitis is a medical emergency that requires early recognition, rapid diagnosis, precise antimicrobial therapy, and aggressive ICU support. In acutely ill patients, the goal of therapy is to institute treatment before the pathologic process of inflammation can produce irreversible progression and/ or death. Time is essential in this situation. Empiric therapy is instituted immediately after diagnosis is made, and it is based on the recognition of a community versus hospital and/or postoperative process. For community-acquired meningitis, usual treatment includes a third-generation cephalosporin (i.e., cefotaxime 3 g IV q6 h or ceftriaxone 2-4 g q12-24 h). Vancomycin should be added to this regimen until culture and susceptibility results are available. A. The number of critically ill patients with impaired host defense mechanisms who are admitted to the ICU has dramatically increased in recent years. The knowledge and recognition of the basic deficiency enable the physician to predict the type and site of infection and allow the institution of early empiric therapy (see Tables 8.6 and 8.7). B. Immunocompromised patients admitted to the ICU should be categorized according to the time of acquisition of infection. Hospital-acquired infections have different etiologic agents compared to those from the community, despite having the same basic immunologic defect. I. If prolonged ICU stay is expected, early placement of subcutaneous catheters is recommended. J. Patients with high fever require special attention to fluid management. K. Antibiotics interact with many other drugs. (See previous tables.) L. Drug-induced fever is not uncommon (common agents are antibiotics, H 2antagonists, and phenytoin). M. Fever may last for several days, even when appropriate antimicrobial therapy has been instituted. N. Closely follow the clinical situation, which is more important than laboratory results. A. Antibiotic Kinetics. The pharmacokinetics of antibiotics depends on several factors. The volume of distribution (V D ) of an antimicrobial is calculated as B. Antibiotic Adjustments. Renal dysfunction in critically ill patients is common. In those patients receiving aminoglycosides, dosage modification is required according to the aminoglycoside clearance: Aminoglycoside clearance cr = + ( )( ) C 0 6 10 . where C cr = creatinine clearance in mL/min. Table 8 .9. D. Other Facts. Some of the atypical mycobacteria commonly encountered in the critical care setting are depicted in Table 8 .10. Ganciclovir 5-10 mg/kg IV q12 h for 14 days Foscarnet 60 mg/kg IV q8 h for 14 days Lifelong suppressive therapy with valganciclovir 900 mg PO q24 h Acyclovir 10-15 mg/kg IV q8 h (e) Syphilis 1. Crystalline penicillin 24 million U/day for 14 days 2. Ceftriaxone 2-4 g/day IV for 14 days Important Facts to Remember in Treating HIV-Infected Patients in the ICU 1. Patients may have more than one infection at the same time. 2. Blood precautions should be instituted immediately to avoid unnecessary exposure Noninfectious processes (i.e., tumors) can mimic infections Patients require a full physical examination daily, including mouth, perirectal area, and eyes Superinfections are common (i.e., fungal and resistant bacteria) When fever persists, consider lumbar puncture, liver, and bone marrow biopsy Obtain CD4-CD8 counts if not recently cloned Code status needs to be established early Privacy of and respect toward patient are essential and mandatory A. Opportunistic infections are the most common causes of morbidity and mortality in patients with human immunodeficiency virus (HIV). Patients with CD4 cells <250 are at risk for developing severe infectious complications. Their approach is depicted in Table 8