Staphylococcus epidermidis infection is mainly a nosocomial infection caused by the Gram-positive bacillus, Staphylococcus epidermidis. It is now the commonest cause of infection associated with indwelling medical catheters, prosthetic devices, and implants. Clinical manifestations are variable depending upon the location of the infection.
Staphylococcus epidermidis (S.epidermidis) is a bacteria residing on human skin which today has become recognized as an opportunistic virulent pathogen [1]. S.epidermidis infections are associated with indwelling medical catheters, devices, and implants like central or peripheral intravenous lines, urinary catheters, prosthetic heart valves, prosthetic joints, and cerebrospinal fluid shunts [2] [3]. These catheters and devices probably become contaminated by the bacteria when being inserted by medical personnel [4]. The infection can be transmitted by healthcare providers due to improper hand hygiene. It can also be transmitted directly through a patient to patient contact and/or through environmental contamination [5].
S.epidermidis infection affects mainly hospitalized patients. Clinical manifestations depend on the location of the infection e.g. a patient with a skin infection will have impetigo while a patient with urinary tract infection may present with dysuria or pyuria. Fever is an omnipresent manifestation along with malaise, asthenia, and fatigue. Low birth weight neonates and immunosuppressed individuals have a higher incidence of septicemia, osteomyelitis, septic arthritis, bursitis, endocarditis, intracardiac abscesses, and myositis. Patients with endocarditis may present with night sweats, unexplained weight loss, cough, dyspnea, pallor, petechiae, and splinter hemorrhages under the nail bed. However, the incidence of serious complications like prosthetic valve endocarditis is relatively low in Staphylococcus epidermidis infection, which is typically either chronic or subacute in nature [6].
S. epidermidis infection should be suspected in individuals with prosthetic devices even if they present up to a year after the surgery with low-grade fever and malaise. It should also be suspected in hospitalized and intensive care unit patients with indwelling catheters and fever. Physical examination may be nonspecific or will reveal purulent discharging wounds, hypotension, cardiac murmur in cases of endocarditis, and abnormal sounds on auscultation in pneumonia. The diagnosis is confirmed if at least two blood cultures obtained on two different days/times are positive for S.epidermidis [5]. Specimen samples for microbiological testing can be acquired from the site of infection e.g. wounds or urine. Gram stain of sputum samples and cultures may be useful to detect the organism in patients with pneumonia. As S. epidermidis is a common contaminant, urine culture must be obtained properly via catheterization or suprapubic aspiration in patients with urinary tract infection [7].
Transthoracic echocardiography (TTE) is recommended in all patients with suspected endocarditis [8]. Transesophageal echocardiography (TEE) can be performed, in absence of contraindications, if TTE does not detect vegetations in clinically suspicious cases of endocarditis [9].
Imaging studies like ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) may be indicated to detect S.epidermidis infection in osteomyelitis or uncertain sites.