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A Late Sternal Wound Infection Caused by Hematogenous Spread of Bacteria
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Slllli~----s_el_ec_te_d_re_po_rt_s_ _ _ _ _ _ __ A Late Sternal Wound Infection Caused by Hematogenous Spread of Bacteria* David C. Stuesse, BA; John H. Robinson, MD; and Dennis S. Dudnsky, MD
A 56-year-old man presented with a stemotomy wound infection 6 months after coronary artery bypass grafting. The organism responsible was group B betahemolytic Streptococcus. This organism was simultaneously cultured from an infected diabetic ulcer on the patient's foot as well as from a total knee prosthesis. The Streptococcus apparently spread hematogenously to the stemum, an extremely rare cause of sternotomy (CHEST 1995; 108:1742-43) wound infection. Key words: hematogenous spread; infection; mediastinitis; sternum after median sternotomy is a rare, yet potentially I nfection lethal complication. Most cases mediastinal wound of
infection are due to surgical contamination and present within a few weeks of median sternotomy. We report a case of sternal wound infection presenting 6 months after coronary artery bypass surgery, apparently caused by hematogenous seeding of bacteria from a distant site. This mechanism of infection, although commonly rep01ted for ortl1opaedic prostl1etic devices, is a rare cause of sternal and mediastinal infection. CASE REPOHT
A 56-year-old white man with a 30-year hist01y of insulindependent diabetes mellitus underwent total arthroplasty of the left knee. Two days later, he developed acute dyspnea and was found to have pulmonary edema. Following diuretic th erapy and clinical stabilization, a persantine-thallium stress test was performed which revealed extensive areas of reve rsible si chemia affecting the inferior, anteroapical, and lateral walls of the heart. Cardiac catheteriz.ation disclosed s evere tripl e-vessel coronary artery disease with mild impairment of left ventricular function. Coronary artery bypass grafting was unde rtaken on th e 9th day following arthroplasty. At that time, the left intemal mammary artery was used to revascularize the left anterior descending coronary artery. Heversed saphenous vein grafts we re applied to the right coronary arte ry and to the marginal branch of the circumflex artery. Intravenously administered vancomycin was adm inistered at a dosage of 1 gpreoperatively as well as at 12-h inte rvals postoperatively for a total of 3 days. Sternal clo*From Medical College of Ohio at Toledo.
Reprint requests: Dr. Dur::insky, Medical College of Ohio at Toledo, Dept of Surgery, Box 10008, Toledo, Ohio 43699-0008 1742
FlGUHE l. CT scan of the thorax showing substernal fluid collection ; culhrres of the material grew group B streptococcus.
sure was accomplished with inte rmpted suhrres of No. 5 stainless steel wire. The postoperative course was complicated only by difficulty with ambulation necessitating transfer to a rehabilitation facility for strengthening and gait training 14 days later. Five months postope ratively, he was seen elsewhere for treatment of an infected ulce r on the plantar aspect of th e right foot. This was initially treated empirically with orally administered ciprofloxacin for 3 weeks. He then noted pain and swelling about the knee prosthesis and late r developed pain in the stemotomy scar. He sought care in an emergency room and was at that time obviously ill with fever, tachycardia, and an elevated le ukocyte count of 14,400/mm 3 . After transfer to our institution, he was noted to have obvious fluctuance and erythe ma overlying the ste rnum as well as th e left knee prosthesis. A dry ulcer was present on the plantar aspect of the right foot. CT scanning confirmed the presence of an abnormal fluid collection beneath the sternum (Fig 1). Needle arthrocentesis revealed pw·ulent material ar·ound the knee prosthesis. Radical de bridement of the sternum was canied out on the same day, with the resultant wound treated by open packing. Simultaneously, incision and drainage with synovectomy were carried out, leaving the knee hardwar·e in situ. The ulce r on the right foot was debrided. Empiric initial preoperative antibiotic therapy consisted of vancomycin and gentamicin. Cultures of blood as well as of tissue from all three surgical sites grew group B beta-hemolytic streptococci. Based on sensitivity data, therapy was continued with intravenously administered cefazolin alone commencing 36 h postoperatively. The patient was managed in the surgical ICU 5 days postoperatively and late r underwent an additional procedure for debridement of the area about the left knee prosthesis as well as the ulce r of the right foot. Subsequently, closure of the knee wound was canied out, retaining the knee prosthesis. With open treatment of the stemal wound, an adequate base of granulation tissue develSelected Reports
oped. Upon return to the operating room 12 days following initial sternal debridement, the wound was closed utilizing bilateral pectoralis major myocutaneous flaps covered by a split-thickness skin graft. Postoperatively, the patient's course was further complicated by an episode of pulmonary embolism confirmed by ventilationperfusion scanning which required treatment with anticoagulants. The sternal flap closure healed satisfactorily, as did the left knee wound. After a 5-week hospital stay, incorporating continuous IV antibiotic therapy with cefazolin , he was discharged with continuation of IV administered cefazolin for 1 more week. This was followed by orally administered cephalexin, 500 mg qid, for a 6-week course. His recovery has been entirely satisfactory, and in 7 m onths of postoperative follow-up, he has not developed evidence of recurrent infection.
Because our patient had no evidence of a local source for infection, such as erosion of a sternal \vire, and in view of the fact that a source existed for bacteremia harboring the same organism, we believe that hematogenous seeding of a sternal wire is the likely source of this patient's sternal wound infection with subsequent mediastinitis. REFERENCES
l Demmy TL, Park SB, Liebler GA, e t al. Recent experience with
2
DISCUSSION
The incidence of sternal wound infection after median sternotomy is generally reported to be 1 to 2%, 1·2 with a mortality rate of 13 to 33%.1 A previous study of sternal wound infections after 835 coronary artery bypass procedures reported a time frame from operation to discovery of infection of 3 to 41 days. 3 Another review reported a m ean time from surgery to infection of 18 days.1 The organisms most commonly responsible for sternal infection are coagulase-negative Staphylococcus species. 3•4 Other frequently encountered organisms include: Proteus mirabilis, Enterobacter, Escherichia coli, Haemophilus injluenzae, group 0 Streptococcus, coagulase-positive Staphylococcus, Corynebacterium, Pseudomonas, as well as polymicrobial infections.1 ·4 It has been r eported that insulin-dependent diabetes mellitus increases the risk for polymicrobial infections. 2 While no prior reported cases of late hematogenous spread of infection to a m edian sternotomy wound were found, hematogenous seeding of orthopedic prosthetic devices commonly is reported. In fact, hematogenous spread has been r eported as the most common mechanism of orthopedic prosthetic infection. The incidence of hematogenous spread of bacteria to total hip prostheses has been reported as 0.75%, and the time period from surgery to discovery of infection ranged in one study from 1 to 96 months. The most common source of infection spread hematogenously to a total hip arthroplasty was reported to be the urogenital tract, although a skin source was reported in one patient. 5 In this case, because of the length of time betw·een surgery and discovery of sternal infection, it is unlikely that the sternal infection was due to contamination at the time of coronary bypass grafting. Length of time from surgery to discovery of infection, however, is not enough to differentiate between surgical contamination and hematogenous seeding. Finding a s eparate source of the bacteria increases the probability that hematogenous spread has occurred. The organism in this case, group B Streptococcus, is an unusual cause of sternal infection by direct contamination and is consistent with the theory that this infection was caused by hematogenous seeding. Although rare, it is important to recognize that a m de ian sternotomy wound can become infected many months after surgery. Foreign material, such as sternal wires, implanted anywhere in the body can harbor bacteria after g eneralized bacteremia, which subsequently can lead to locoregional infection.
3 4 5
major sternal wound complications. Ann Thorac Surg 1990; 49:458-62 Loop FD, Lytle BW, Cosgrove DM, e t al. Sternal wound complications after isolated coronary artery bypass grafting: early and late mortality, morbidity, and cost of care. Ann Thorac Surg 1990; 49:179-87 Kohman LJ, Coleman MJ, Parker FB. Bacteremia and sternal infection after coronary artery bypass grafting. Ann Thorac Surg 1990; 49:454-57 Hazelrigg SR, Wellons HA Jr, Schneider JA, e t al. Wound complications after median sternotomy. J Thorac Cardiovasc Surg 1989; 98:1096-99 Schmalzried TP, Amstutz HC, Man-Kuan A, e t al. Etiology of deep s epsis in total hip arthroplasty. Clin Orthop 1992; 280:200-07
Three-Dimensional Image Reconstruction of Partial Anomalous Pulmonary Venous Return to the Superior Vena Cava* Brigitte Zwetsch, MD; Stephan Wicky, MD; Reto Meuli, MD; and Pierre Schnyder, MD
A case of a rare partial anomalous pulmonary venous return of the right upper lobe into the superior vena cava is reported. Multiple three-dimensional image reconstructions in association with spiral CT are used in the aim of clarifying this abnormality of pulmonary venous drainage. (CHEST 1995; 108:1743-45)
ASD=atrial septal defect; 3D=three-dimensional; PAPVR=partial anomalous pulmonary venous return; SCT=spiral CT; SVC=superior vena cava
Key words: concomitant cardiac diseases; partial anomalous pulmonary venous return (PAPVR); scimitar syndrome; spiral computed tomography (SCT); three-dimensional (30 ) image reconstructions; vena cava superior
Dutial anomalous pulmonary venous return (PAPVR) is a dysgenesis in which the embryonic pulmonary venous plexus does not anastomose to the primitive sinus venosus. As a result, abnormal communications between the
r
*From the Department of Radiology, University Hospital CHUV, Lausanne, Switzerland. Reprint requests: Dr. Schnyder, Departme nt of Radiology, Unicersity Hospital CHUV, 1011 Lausanne, Switzerland CHEST I 108 I 6 I DECEMBER, 1995
1743
.====.
- . = =
Slllli~----s_el_ec_te_d_re_po_rt_s_ _ _ _ _ _ __ A Late Sternal Wound Infection Caused by Hematogenous Spread of Bacteria* David C. Stuesse, BA; John H. Robinson, MD; and Dennis S. Dudnsky, MD
A 56-year-old man presented with a stemotomy wound infection 6 months after coronary artery bypass grafting. The organism responsible was group B betahemolytic Streptococcus. This organism was simultaneously cultured from an infected diabetic ulcer on the patient's foot as well as from a total knee prosthesis. The Streptococcus apparently spread hematogenously to the stemum, an extremely rare cause of sternotomy (CHEST 1995; 108:1742-43) wound infection. Key words: hematogenous spread; infection; mediastinitis; sternum after median sternotomy is a rare, yet potentially I nfection lethal complication. Most cases mediastinal wound of
infection are due to surgical contamination and present within a few weeks of median sternotomy. We report a case of sternal wound infection presenting 6 months after coronary artery bypass surgery, apparently caused by hematogenous seeding of bacteria from a distant site. This mechanism of infection, although commonly rep01ted for ortl1opaedic prostl1etic devices, is a rare cause of sternal and mediastinal infection. CASE REPOHT
A 56-year-old white man with a 30-year hist01y of insulindependent diabetes mellitus underwent total arthroplasty of the left knee. Two days later, he developed acute dyspnea and was found to have pulmonary edema. Following diuretic th erapy and clinical stabilization, a persantine-thallium stress test was performed which revealed extensive areas of reve rsible si chemia affecting the inferior, anteroapical, and lateral walls of the heart. Cardiac catheteriz.ation disclosed s evere tripl e-vessel coronary artery disease with mild impairment of left ventricular function. Coronary artery bypass grafting was unde rtaken on th e 9th day following arthroplasty. At that time, the left intemal mammary artery was used to revascularize the left anterior descending coronary artery. Heversed saphenous vein grafts we re applied to the right coronary arte ry and to the marginal branch of the circumflex artery. Intravenously administered vancomycin was adm inistered at a dosage of 1 gpreoperatively as well as at 12-h inte rvals postoperatively for a total of 3 days. Sternal clo*From Medical College of Ohio at Toledo.
Reprint requests: Dr. Dur::insky, Medical College of Ohio at Toledo, Dept of Surgery, Box 10008, Toledo, Ohio 43699-0008 1742
FlGUHE l. CT scan of the thorax showing substernal fluid collection ; culhrres of the material grew group B streptococcus.
sure was accomplished with inte rmpted suhrres of No. 5 stainless steel wire. The postoperative course was complicated only by difficulty with ambulation necessitating transfer to a rehabilitation facility for strengthening and gait training 14 days later. Five months postope ratively, he was seen elsewhere for treatment of an infected ulce r on the plantar aspect of th e right foot. This was initially treated empirically with orally administered ciprofloxacin for 3 weeks. He then noted pain and swelling about the knee prosthesis and late r developed pain in the stemotomy scar. He sought care in an emergency room and was at that time obviously ill with fever, tachycardia, and an elevated le ukocyte count of 14,400/mm 3 . After transfer to our institution, he was noted to have obvious fluctuance and erythe ma overlying the ste rnum as well as th e left knee prosthesis. A dry ulcer was present on the plantar aspect of the right foot. CT scanning confirmed the presence of an abnormal fluid collection beneath the sternum (Fig 1). Needle arthrocentesis revealed pw·ulent material ar·ound the knee prosthesis. Radical de bridement of the sternum was canied out on the same day, with the resultant wound treated by open packing. Simultaneously, incision and drainage with synovectomy were carried out, leaving the knee hardwar·e in situ. The ulce r on the right foot was debrided. Empiric initial preoperative antibiotic therapy consisted of vancomycin and gentamicin. Cultures of blood as well as of tissue from all three surgical sites grew group B beta-hemolytic streptococci. Based on sensitivity data, therapy was continued with intravenously administered cefazolin alone commencing 36 h postoperatively. The patient was managed in the surgical ICU 5 days postoperatively and late r underwent an additional procedure for debridement of the area about the left knee prosthesis as well as the ulce r of the right foot. Subsequently, closure of the knee wound was canied out, retaining the knee prosthesis. With open treatment of the stemal wound, an adequate base of granulation tissue develSelected Reports
oped. Upon return to the operating room 12 days following initial sternal debridement, the wound was closed utilizing bilateral pectoralis major myocutaneous flaps covered by a split-thickness skin graft. Postoperatively, the patient's course was further complicated by an episode of pulmonary embolism confirmed by ventilationperfusion scanning which required treatment with anticoagulants. The sternal flap closure healed satisfactorily, as did the left knee wound. After a 5-week hospital stay, incorporating continuous IV antibiotic therapy with cefazolin , he was discharged with continuation of IV administered cefazolin for 1 more week. This was followed by orally administered cephalexin, 500 mg qid, for a 6-week course. His recovery has been entirely satisfactory, and in 7 m onths of postoperative follow-up, he has not developed evidence of recurrent infection.
Because our patient had no evidence of a local source for infection, such as erosion of a sternal \vire, and in view of the fact that a source existed for bacteremia harboring the same organism, we believe that hematogenous seeding of a sternal wire is the likely source of this patient's sternal wound infection with subsequent mediastinitis. REFERENCES
l Demmy TL, Park SB, Liebler GA, e t al. Recent experience with
2
DISCUSSION
The incidence of sternal wound infection after median sternotomy is generally reported to be 1 to 2%, 1·2 with a mortality rate of 13 to 33%.1 A previous study of sternal wound infections after 835 coronary artery bypass procedures reported a time frame from operation to discovery of infection of 3 to 41 days. 3 Another review reported a m ean time from surgery to infection of 18 days.1 The organisms most commonly responsible for sternal infection are coagulase-negative Staphylococcus species. 3•4 Other frequently encountered organisms include: Proteus mirabilis, Enterobacter, Escherichia coli, Haemophilus injluenzae, group 0 Streptococcus, coagulase-positive Staphylococcus, Corynebacterium, Pseudomonas, as well as polymicrobial infections.1 ·4 It has been r eported that insulin-dependent diabetes mellitus increases the risk for polymicrobial infections. 2 While no prior reported cases of late hematogenous spread of infection to a m edian sternotomy wound were found, hematogenous seeding of orthopedic prosthetic devices commonly is reported. In fact, hematogenous spread has been r eported as the most common mechanism of orthopedic prosthetic infection. The incidence of hematogenous spread of bacteria to total hip prostheses has been reported as 0.75%, and the time period from surgery to discovery of infection ranged in one study from 1 to 96 months. The most common source of infection spread hematogenously to a total hip arthroplasty was reported to be the urogenital tract, although a skin source was reported in one patient. 5 In this case, because of the length of time betw·een surgery and discovery of sternal infection, it is unlikely that the sternal infection was due to contamination at the time of coronary bypass grafting. Length of time from surgery to discovery of infection, however, is not enough to differentiate between surgical contamination and hematogenous seeding. Finding a s eparate source of the bacteria increases the probability that hematogenous spread has occurred. The organism in this case, group B Streptococcus, is an unusual cause of sternal infection by direct contamination and is consistent with the theory that this infection was caused by hematogenous seeding. Although rare, it is important to recognize that a m de ian sternotomy wound can become infected many months after surgery. Foreign material, such as sternal wires, implanted anywhere in the body can harbor bacteria after g eneralized bacteremia, which subsequently can lead to locoregional infection.
3 4 5
major sternal wound complications. Ann Thorac Surg 1990; 49:458-62 Loop FD, Lytle BW, Cosgrove DM, e t al. Sternal wound complications after isolated coronary artery bypass grafting: early and late mortality, morbidity, and cost of care. Ann Thorac Surg 1990; 49:179-87 Kohman LJ, Coleman MJ, Parker FB. Bacteremia and sternal infection after coronary artery bypass grafting. Ann Thorac Surg 1990; 49:454-57 Hazelrigg SR, Wellons HA Jr, Schneider JA, e t al. Wound complications after median sternotomy. J Thorac Cardiovasc Surg 1989; 98:1096-99 Schmalzried TP, Amstutz HC, Man-Kuan A, e t al. Etiology of deep s epsis in total hip arthroplasty. Clin Orthop 1992; 280:200-07
Three-Dimensional Image Reconstruction of Partial Anomalous Pulmonary Venous Return to the Superior Vena Cava* Brigitte Zwetsch, MD; Stephan Wicky, MD; Reto Meuli, MD; and Pierre Schnyder, MD
A case of a rare partial anomalous pulmonary venous return of the right upper lobe into the superior vena cava is reported. Multiple three-dimensional image reconstructions in association with spiral CT are used in the aim of clarifying this abnormality of pulmonary venous drainage. (CHEST 1995; 108:1743-45)
ASD=atrial septal defect; 3D=three-dimensional; PAPVR=partial anomalous pulmonary venous return; SCT=spiral CT; SVC=superior vena cava
Key words: concomitant cardiac diseases; partial anomalous pulmonary venous return (PAPVR); scimitar syndrome; spiral computed tomography (SCT); three-dimensional (30 ) image reconstructions; vena cava superior
Dutial anomalous pulmonary venous return (PAPVR) is a dysgenesis in which the embryonic pulmonary venous plexus does not anastomose to the primitive sinus venosus. As a result, abnormal communications between the
r
*From the Department of Radiology, University Hospital CHUV, Lausanne, Switzerland. Reprint requests: Dr. Schnyder, Departme nt of Radiology, Unicersity Hospital CHUV, 1011 Lausanne, Switzerland CHEST I 108 I 6 I DECEMBER, 1995
1743