A 34-year-old man is admitted to the hospital following laparotomy for a gunshot wound. He received 5 units of packed red blood cells during surgery. Prophylactic perioperative ampicillin/sulbactam was given, and the patient performed incentive spirometry. On post-operative day 6, he develops a fever of 38.7 C (101.7 F). Blood pressure is 120/76 mm Hg, pulse is 97/min, and respirations are 14/min. On examination, the patient is alert and in no acute distress. The oropharynx is clear. Cardiopulmonary examination is normal. The abdomen is soft and nontender, and there is no discharge from the wound. He has a right internal jugular triple-lumen catheter and a Foley catheter in place. The extremities have no swelling or erythema. Two days later, blood cultures of samples taken from the triple-lumen catheter and a peripheral site grow coagulase-negative staphylococci in 4 of 4 bottles. What is the most likely cause of this patient's current condition?

Question

A 34-year-old man is admitted to the hospital following laparotomy for a gunshot wound.  He received 5 units of packed red blood cells during surgery.  Prophylactic perioperative ampicillin/sulbactam was given, and the patient performed incentive spirometry.  On post-operative day 6, he develops a fever of 38.7 C (101.7 F).  Blood pressure is 120/76 mm Hg, pulse is 97/min, and respirations are 14/min.  On examination, the patient is alert and in no acute distress.  The oropharynx is clear.  Cardiopulmonary examination is normal.  The abdomen is soft and nontender, and there is no discharge from the wound.  He has a right internal jugular triple-lumen catheter and a Foley catheter in place.  The extremities have no swelling or erythema.  Two days later, blood cultures of samples taken from the triple-lumen catheter and a peripheral site grow coagulase-negative staphylococci in 4 of 4 bottles.  What is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d920_43cf_bc81_058f542b15a0_MD0003_00 This patient developed fever on postoperative day 6, and subsequent blood cultures grew coagulase-negative staphylococci (CoNS). Although these minimally virulent skin commensal flora organisms are a common blood culture contaminant, the presence of growth in 4 of 4 bottles from both the catheter and the peripheral venous site suggest a bloodstream infection rather than contamination (Choice A). Catheter-related bloodstream infection (CRBSI) typically occurs >48 hours after catheter insertion. Most cases are due to the migration of skin commensals through the catheter lumen or around the exterior of the catheter into the vessel lumen. Although Enterococcus, Staphylococcus aureus, and Candida are often isolated, the most common cause of CRBSI is CoNS (eg, Staphylococcus epidermidis). Patients usually have fever and purulence/erythema around the catheter insertion site, but these manifestations are not always present. Sepsis (eg, hypotension, tachycardia) frequently occurs. Patients with suspected CRBSI should have 2 sets of blood cultures: 1 set from a peripheral site and 1 set from the catheter. This helps differentiate contamination (eg, 1 of 4 cultures is positive) from true infection (eg, 4 of 4 cultures are positive). With CoNS, other microbiologic features that suggest infection rather than contamination include: growth in both aerobic and anerobic bottles; and multiple blood cultures with the same organism with the exact same drug susceptibility. Empiric, broad-spectrum antibiotics are typically administered until culture results return. (Choice C) Risk of urinary tract infection increases when Foley catheters are in place for >3 days. Although this patient's Foley catheter has likely been in place since the operation, most Foley catheter-related infections are caused by gram-negative enteric organisms such as Escherichia coli. CoNS is an atypical cause of urinary tract infection. (Choice D) Hospital-acquired pneumonia occurs >48 hours after admission. Although this patient has been hospitalized for 6 days, his normal pulmonary examination and respiratory rate make pneumonia unlikely. In addition, CoNS would be an atypical cause of pneumonia; most hospital-acquired pneumonias are caused by gram-negative bacilli (eg, Pseudomonas, Klebsiella, E coli), Streptococcus, or S aureus. (Choice E) Surgical site infection is a common cause of postoperative fever, but patients usually have signs of infection at the surgical site (eg, erythema, purulence, wound dehiscence). (Choice F) Transfusion-transmitted bacterial infection (eg, due to bacteria transmitted from the donor's blood or skin or from environmental contamination) can cause high fever, but most cases present within 30 minutes of transfusion, not 6 days later. In addition, the most common cause is gram-negative organisms rather than CoNS. Educational objective: Coagulase-negative staphylococci (CoNS) are the most common cause of catheter-related bloodstream infection. Although CoNS is a frequent blood culture contaminant, bloodstream infection is likely in patients who have blood culture growth in ≥2 bottles (both aerobic and anaerobic) with the same organism and drug susceptibility. References: Coagulase-negative staphylococcal infections. (http://www.ncbi.nlm.nih.gov/pubmed/19135917) Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study. (http://www.ncbi.nlm.nih.gov/pubmed/15306996)

A 34-Year-Old Man Is Admitted to the Hospital Following Laparotomy