**2.5 Meningitis and encephalitis**

*Trauma and Emergency Surgery - The Role of Damage Control Surgery*

producing organisms (ESBLs) [19].

**2.3 Musculoskeletal**

Uncomplicated cystitis and pyelonephritis in women is typically caused by *Escherichia coli,* though *Proteus mirabilis, Klebsiella pneumoniae,* and *Streptococcus saprophyticus* are also relatively common [18]. As such, empiric treatment for uncomplicated urinary tract infections is best tailored to the regional *E. coli* sensitivities [18]. A complicated urinary tract infection is one which is associated with a condition that increases the risk for therapeutic failure [19]. These risk factors include diabetes, pregnancy, ureterolithiasis, renal failure, >7 days of symptoms, or an indwelling urinary device [19]. The microbial spectrum of complicated UTI is more varied and includes not only the typical organisms associated with uncomplicated UTI but also *Pseudomonas, Staphylococcus*, and *Serratia* species as well as fungi [19]. Complicated lower urinary tract infections may be managed as an outpatient; indications for hospitalization include inability to tolerate oral therapy or suspected infection with an organism resistant to oral therapies, such as extended-spectrum beta-lactamase

A comprehensive physical examination is of utmost importance in patients with

a potential musculoskeletal infection as laboratory evaluation in these patients is generally non-diagnostic. Poor circulation and neuropathy are important risk factors for the development of musculoskeletal infections, and, as such, patients may not be able localize the source of their infection. Examination should include turning the patient to examine the back, palpation of the large joints, and examination of the feet and genitourinary regions for skin changes, which are often the only clue to the presence of a musculoskeletal infection [20, 21]. Comparison with the contralateral side can help to provide a baseline with which to compare for abnormalities. Practitioners should also evaluate for the presence of decubitus ulcers, which can become a nidus for osteomyelitis or bacteremia. Crepitus or pain out of proportion to examination should prompt concern for necrotizing soft tissue infection. Erythema, swelling, or pain with passive motion in a joint are concerning for a septic joint, with the knee and hip being the most common sources [22]. Risk factors for musculoskeletal infections include vasculopathy, diabetes, surgery, and immunocompromise [20]. *Staphylococcus aureus* or *Streptococcus pyogenes-*associated cellulitis is the most common cause of sepsis secondary to musculoskeletal infection [20]. While magnetic resonance imaging (MRI), surgical pathology, or culture is often necessary for the definitive diagnosis of most musculoskeletal infections, this

should not delay early and aggressive source control in the ED.

Infectious pericarditis, myocarditis, and endocarditis as causes of sepsis can be easily missed in the emergency department due to their often subtle and variable presentations. Acute infectious pericarditis describes infection of the fibrous tissue encasing the heart and the base of the aorta and vena cava. Echoviruses and coxsackie A and B viruses account for nearly 90% of cases of infective pericarditis, with bacterial, parasitic, and fungal organisms accounting for the minority of cases [23]. The most common bacterial pathogens implicated in infective pericarditis are *Streptococcus pneumoniae* and *Staphylococcus auresus* [23]. The diagnosis of acute pericarditis is based on the presence of characteristic chest pain and electrocardiographic abnormalities [23]. Auscultation of a friction rub is helpful but is poorly sensitive for the diagnosis [24]. Infective myocarditis describes infection of the myocardial tissue, with coxsackie B being the most common cause. Other common causes include influenza virus, adenovirus, hepatitis C virus, parvovirus

**22**

**2.4 Cardiac**

Meningitis is an infection of the meningeal lining of the central nervous system by bacteria, viruses, or fungi, with bacterial causes accounting the highest global burden [26]. Encephalitis describes infection of the cerebral parenchyma with a pathogen. *Streptococcus pneumonia,* group B streptococci, and *Neisseria meningitidis* are the most common causes of bacterial meningitis, with *Listeria monocytogenes* also being common in children, immunocompromised individuals, and adults greater than 50 years of age [26, 27]. Common viral causes of meningitis and encephalitis include herpesviruses, enteroviruses, and cytomegalovirus [28]. Fever, altered mental status, and nuchal rigidity are the classically described triad of meningitis, but the majority of patients in clinical practice only manifest one or two of these symptoms [26]. Lumbar puncture with cerebrospinal fluid (CSF) analysis is the diagnostic test of choice for meningitis. CT imaging should precede lumbar puncture in patients whose symptoms may be secondary to mass effect, such as those with immunocompromise, new seizure, papilledema, focal neurologic deficit, or altered mental status [26, 28, 29] Importantly, diagnostic studies should not delay the administration of antimicrobials in patients with suspected meningitis or encephalitis. Administration of antimicrobials prior to lumbar puncture has been shown to have minimal effect on chemistry and cytology findings studies of CSF but may lead to a falsely negative Gram stain or culture [30–32]. This should not affect the decision to start empiric antibiotics early in these patients.

## **2.6 Spinal column infections**

Infections of the spinal column are an important diagnostic consideration in all patients presenting to the ED with back pain. Potential sources of infection in the spinal column include vertebral osteomyelitis, discitis, and epidural abscess. These infections are commonly missed, as there is remarkable variability in patient presentation and fever is seen in only half of these patients [33–35] Neurologic deficits likewise may or may not be present [33–35]. Risk factors for infections of the spinal column include immunocompromise, recent instrumentation, spinal implants, and use of intravenous drugs [35]. Magnetic resonance imaging (MRI) is the preferred imaging study in patients with suspected spinal column infection [35]. If MRI is unavailable, CT myelography can also be used [35].

#### **2.7 Intraabdominal infections**

Causes of intraabdominal sepsis include abdominal and pelvic abscesses, pelvic inflammatory disease, spontaneous bacterial peritonitis, cholecystitis or cholangitis, ruptured hollow viscus, or infection of the gastrointestinal tract. While abdominal sources for sepsis are common in the ED, the diagnosis may be hampered by examination difficulties secondary to the patient's mental status or body habitus. Altered consciousness can impede a patient's ability to localize their discomfort, and many abdominal pathologies have no manifestations on external visual examination. As such, a thorough abdominal examination is of vital importance in altered patients. Although these patients may be unable to verbalize discomfort, absent bowel sounds, abdominal distention, or abdominal rigidity on examination can be clues to the presence of intraabdominal pathology [36–38]. Additionally, grimacing, guarding, or reflex tachycardia can be useful indicators of pain in patients are altered or obtunded [36–38]. Pelvic examination should be done if a pelvic source is suspected or if there is concern for toxic shock syndrome secondary to a retained vaginal foreign body [38].
