Charles E. Edmiston

Treatment of Hickman Catheter Sepsis Using Antibiotic Lock Technique

Antibiotic lock therapy, an alternative treatment for Hickman catheter sepsis, was evaluated in six recipients of prolonged outpatient intravenous therapy. Twenty-two episodes of catheter sepsis were identified, involving coagulase-negative staphylococci (11), gram-negative bacilli (3), gram-positive bacilli (1), yeast (4), and mixed bacteria or fungi (3). In a select group of patients, treatment was successful 92% of the time.

In Vitro Activities of Moxifloxacin against 900 Aerobic and Anaerobic Surgical Isolates from Patients with Intra-Abdominal and Diabetic Foot Infections

ABSTRACT The in vitro activities of moxifloxacin, ciprofloxacin, levofloxacin, gatifloxacin, imipenem, piperacillin-tazobactam, clindamycin, and metronidazole against 900 surgical isolates were determined using NCCLS testing methods. Moxifloxacin exhibited good to excellent antimicrobial activity against most aerobic (90.8%) and anaerobic (97.1%) microorganisms, suggesting that it may be effective for the treatment of polymicrobial surgical infections.

Do surgical care bundles reduce the risk of surgical site infections in patients undergoing colorectal surgery? A systematic review and cohort meta-analysis of 8,515 patients.

BACKGROUND Care bundles are a strategy that can be used to reduce the risk of surgical site infection (SSI), but individual studies of care bundles report conflicting outcomes. This study assesses the effectiveness of care bundles to reduce SSI among patients undergoing colorectal surgery. METHODS We performed a systematic review and meta-analysis of randomized controlled trials, quasi-experimental studies, and cohort studies of care bundles to reduce SSI. The search strategy included database and clinical trials register searches from 2012 until June 2014, searching reference lists of retrieved studies and contacting study authors to obtain missing data. The Downs and Black checklist was used to assess the quality of all studies. Raw data were used to calculate pooled relative risk (RR) estimates using Cochrane Review Manager. The I(2) statistic and funnel plots were performed to identify publication bias. Sensitivity analysis was carried out to examine the influence of individual data sets on pooled RRs. RESULTS Sixteen studies were included in the analysis, with 13 providing sufficient data for a meta-analysis. Most study bundles included core interventions such as antibiotic administration, appropriate hair removal, glycemic control, and normothermia. The SSI rate in the bundle group was 7.0% (328/4,649) compared with 15.1% (585/3,866) in a standard care group. The pooled effect of 13 studies with a total sample of 8,515 patients shows that surgical care bundles have a clinically important impact on reducing the risk of SSI compared to standard care with a CI of 0.55 (0.39-0.77; P = .0005). CONCLUSION The systematic review and meta-analysis documents that use of an evidence-based, surgical care bundle in patients undergoing colorectal surgery significantly reduced the risk of SSI.

Preoperative Shower Revisited: Can High Topical Antiseptic Levels Be Achieved on the Skin Surface Before Surgical Admission?

BACKGROUND Skin asepsis is a sentinel strategy for reducing risk of surgical site infections. In this study, chlorhexidine gluconate (CHG) skin concentrations were determined after preoperative showering/skin cleansing using 4% CHG soap or 2% CHG-impregnated polyester cloth. STUDY DESIGN Subjects were randomized to one of three shower (4% soap)/skin cleansing (2% cloth) groups (n = 20 per group): (group 1 A/B) evening, (group 2 A/B) morning, or (group 3 A/B) evening and morning. After showering or skin cleansing, volunteers returned to the investigators laboratory where CHG skin surface concentrations were determined at five separate skin sites. CHG concentrations were compared with CHG minimal inhibitory concentration that inhibits 90% (MIC(90)) of staphylococcal skin isolates. RESULTS CHG MIC(90) for 61 skin isolates was 4.8 parts per million (ppm). In group 1A, 4% CHG skin concentrations ranged from 17.2 to 31.6 ppm, and CHG concentrations were 361.5 to 589.5 ppm (p < 0.0001) in group 1B (2%). In group 2A (4%), CHG levels ranged from 51.6 to 119.6 ppm and 848.1 to 1,049.6 ppm in group 2B (2%), respectively (p < 0.0001). CHG levels ranged from 101.4 to 149.4 ppm in the 4% CHG group (group 3A) compared with 1,484.6 to 2,031.3 ppm in 2% CHG cloth (group 3B) group (p < 0.0001). Effective CHG levels were not detected in the 4% CHG group in selected sites in seven (35%) subjects in group 1A, three (15%) in group 2A, and five (25%) in group 3A. CONCLUSIONS Effective CHG levels were achieved on most skin sites after using 4% CHG; gaps in antiseptic coverage were noted at selective sites even after repeated application. Use of the 2% CHG polyester cloth resulted in considerably higher skin concentrations with no gaps in antiseptic coverage. Effective decolonization of the skin before hospital admission can play an important role in reducing risk of surgical site infections.

Efficacy of a β-lactamase Inhibitor Combination for Serious Intra-abdominal Infections

A double-blind trial was conducted in 385 patients with suspected bacterial intra-abdominal infections to compare the efficacy and safety of ampicillin-sulbactam with cefoxitin. Patients were randomized to receive either 3 g ampicillin-sulbactam (2 g ampicillin-1 g sulbactam), or 2 g cefoxitin, every 6 hours. To be evaluable, patients had to demonstrate positive culture evidence of peritoneal infection at the time of operation. A total of 197 patients were evaluable for clinical efficacy. The two treatment groups were comparable in demographic features and in the presence of risk factors for infection. Clinical success (absence of infection and of adverse drug reaction) was observed in 86% of patients in the ampicillin-sulbactam group and 78% in the cefoxitin group. Eradication of infection occurred in 88% of the ampicillin-sulbactam group and 79% of the cefoxitin group. There were no differences in the nature or frequency of side effects observed in the two groups. Ampicillin-sulbactam demonstrated no difference in safety or efficacy when compared with cefoxitin in the treatment of serious intra-abdominal infections of bacterial origin.

Effects of maternal obesity on tissue concentrations of prophylactic cefazolin during cesarean delivery.

OBJECTIVE: To estimate the adequacy of antimicrobial activity of preoperative antibiotics at the time of cesarean delivery as a function of maternal obesity. METHODS: Twenty-nine patients scheduled for cesarean delivery were stratified according to body mass index (BMI) category, with 10 study participants classified as lean (BMI less than 30), 10 as obese (BMI 30–39.9), and nine as extremely obese (BMI 40 or higher). All patients were given a dose of 2 g cefazolin 30–60 minutes before skin incision. Antibiotic concentrations from adipose samples, collected after skin incision and before skin closure, along with myometrial and serum samples, were analyzed with microbiological agar diffusion assay. RESULTS: Cefazolin concentrations within adipose tissue obtained at skin incision were inversely proportional to maternal BMI (r=−0.67, P<.001). The mean adipose concentration was 9.4 plus or minus 2.7 micrograms/g in the lean group of women compared with 6.4 plus or minus 2.3 micrograms/g in the obese group (P=.009) and 4.4 plus or minus 1.2 micrograms/g in the extremely obese group (P<.001). Although all specimens demonstrated therapeutic cefazolin levels for gram-positive cocci (greater than 1 microgram/g), a considerable portion of obese and extremely obese did not achieve minimal inhibitory concentrations of greater than 4 micrograms/g for Gram-negative rods in adipose samples at skin incision (20% and 33.3%, respectively) or closure (20.0% and 44.4%, respectively). No significant difference in cefazolin concentration was observed in mean closure adipose, myometrial, or serum specimens across the BMI categories. CONCLUSION: Pharmacokinetic analysis suggests that present antibiotic prophylaxis dosing may fail to provide adequate antimicrobial coverage in obese patients during cesarean delivery. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00980486. LEVEL OF EVIDENCE: II

In situ replacement of arterial prosthesis infected by bacterial biofilms: long-term follow-up.

PURPOSE Bacterial biofilm infections of vascular prostheses are characterized by an absence of systemic sepsis, a fluid-filled cavity surrounding the graft, a draining sinus tract, and microorganisms that must be removed from the fabric prosthesis for bacterial culture. METHODS Since 1987 we have treated 20 infected grafts with prosthetic excision and in situ replacement in 14 men and 6 women. The time from initial graft implantation to diagnosis of graft infection ranged from 3 months to 14 years (mean 4.5 years). The original graft (Dacron-17, polytetrafluoroethylene-3) was an aortobifemoral in 14, axillofemoral femorofemoral in 3, iliofemoral in 2, and femoropopliteal in 1 patient. Presenting symptoms were groin false aneurysm with perigraft fluid in 10, inflammatory mass in 6, and sinus tract in 4. At surgery all unincorporated graft material and the perigraft capsule were excised from a point where the proximal graft was incorporated, including debridement of vessels at the distal anastomosis. Of the 14 aortobifemoral grafts, only the femoral limbs were excised at the initial presentation of biofilm infection. The conduit was replaced with an in situ polytetrafluoroethylene interposition graft, which was covered with a gracilis or sartorius muscle flap when possible. RESULTS All surgical sites healed, all grafts remained patent, and there was no limb loss. After ultrasonic oscillation of the explanted graft, bacterial cultures recovered coagulase-negative Staphylococcus species in 14, coagulase-positive Staphylococcus species in one, both species in three, with no growth from two specimens. During follow-up, two patients have had clinical involvement in the proximal intraabdominal portion of the graft that had not been previously resected. In all grafts, the in situ replacement graft remained well incorporated. CONCLUSION In situ graft replacement is effective treatment for biofilm infections of vascular prostheses. Because of the indolent nature of these infections, subsequent infection of previously uninvolved graft segments may be expected.

Elimination of Intraluminal Colonization by Antibiotic Lock in Silicone Vascular Catheters

An in vitro model was designed to evaluate the efficacy of instilled antimicrobials to reduce or eliminate intraluminal microbial colonization. Minimal inhibitory concentration and minimal bactericidal concentration activity of appropriate test anti-infectives were determined using standard methodology against clinically derived and reference test strains commonly associated with catheter-related infection. Drug activity was validated by bioassay for the test anti-infectives. Reference and clinical test strains were inoculated to the intraluminal surface of silicone catheter segments and incubated for 30 min, after which the inoculum was replaced with total parenteral nutrition (TPN) solution and reincubated for 12 h. For 7 d, instillation of antibiotic and TPN solution was alternated every 12 h to simulate clinical conditions. On days 1, 4, and 7, catheter segments were rinsed, bisected, and sonicated for quantitative plate count to determine mean microbial counts per centimeter of catheter surface. Catheter segments were also prepared for scanning electron microscopy. A significant decrease in staphylococcal intraluminal colonization after instillation of nafcillin, ceftriaxone, gentamicin, and vancomycin was demonstrated (P < 0.001). Aztreonam, ceftriaxone, and gentamicin completely eliminated gram-negative catheter colonization (P < 0.001). Yeast was eradicated from the internal catheter surface after treatment with amphoteracin B, and fluconazole significantly decreased intraluminal colonization (P < 0.001). Results show a significant decrease in staphylococcal, gram-negative, and fungal intraluminal colonization after instillation of appropriate antimicrobial. In vitro results support early clinical success using this technique. Future studies are warranted to identify optimal drug concentrations and dosing intervals.

Evidence for using chlorhexidine gluconate preoperative cleansing to reduce the risk of surgical site infection.

Surgical site infections are associated with significant patient morbidity and mortality and are the third most frequently reported health care-associated infection. A suggested risk reduction strategy has been the preadmission shower or skin cleansing with chlorhexidine gluconate (CHG). Although older clinical trials question the clinical efficacy of cleansing with CHG, recent evidence-based scientific and clinical studies support two types of CHG application (ie, a 2% CHG-coated cloth or 4% CHG soap) using a standardized, timed process before hospital admission as an effective strategy for reducing the risk of postoperative surgical site infection.

Anastomotic femoral pseudoaneurysm: An investigation of occult infection as an etiologic factor

Occult infection was investigated as an etiologic factor in the formation of femoral anastomotic pseudoaneurysms associated with prosthetic vascular grafts. Forty-five femoral pseudoaneurysms with no clinical evidence of infection 10 to 173 months after prosthetic graft placement were consecutively studied. The explanted Dacron or explanted polytetrafluoroethylene graft material was cultured in trypticase soy broth and ultrasonically oscillated to remove adherent bacteria. All patients were treated by excision of the pseudoaneurysm and surrounding perigraft capsule and in situ replacement with an interposition prosthetic graft. Thirty-two bacterial isolates were recovered from 27 (60%) of the specimens, with coagulase negative staphylococci (Staphylococcus epidermidis S. warneri, S. hominis, S. capitis) accounting for 24 of the recovered species. No infection of the replacement graft developed in any patient and no recurrent pseudoaneurysms were observed. Bacterial colonization may occur at implantation or during subsequent procedures when the prosthetic graft is exposed. This chronic infection can be diagnosed by means of sensitive culture techniques that dislodge adherent bacteria from the graft surface. On grounds of the observations reported in this study, there appears to be suggestive evidence that an occult infectious process may be one of the factors that play a role in the development of some femoral anastomotic pseudoaneurysms.