Prophylactic antibiotics for surgery

Current Antimicrobial Use in Horses Undergoing Exploratory Celiotomy: A Survey of Board-Certified Equine Specialists

In the past decade, there has been a considerable increase in the recognition of antimicrobial resistance in equine practice. The objective of this study was to survey the current clinical use of antimicrobials for a commonly performed surgical procedure (exploratory celiotomy) with the goal of understanding how recent literature and changes in microbial resistance patterns may have impacted antimicrobial selection practices. An electronic survey was distributed to veterinary professionals within the American College of Veterinary Internal Medicine (ACVIM) and the American College of Veterinary Surgery (ACVS). A total of 113 completed surveys were returned. Practitioners reported antimicrobials were most frequently given 30-60 min preoperatively (63.1%). Two antimicrobial classes were typically administered (95.5%), with gentamicin (98.2%) and potassium penicillin (74.3%) being the most common. Antimicrobials were typically not re-dosed intraoperatively (78.6%). Factors that affected overall treatment length postoperatively included resection (81.4%), bloodwork (75.2%), enterotomy (74.3%), fever (85.0%), incisional complications (76.1%), and thrombophlebitis (67.3%). The most common duration of antimicrobial use was 1-3 d for non-strangulating lesions (54.4% of cases) and inflammatory conditions such as enteritis or peritonitis (50.4%), and 3-5 d for strangulating lesions (63.7%). Peri-incisional and intra-abdominal antimicrobials were used by 24.8% and 11.5% of respondents, respectively. In summary, antimicrobial usage patterns were highly variable among practitioners and, at times, not concordant with current literature.

Antimicrobial use in horses undergoing colic surgery

BACKGROUND

Recommendations for antimicrobial prophylaxis for surgery are well-described in human medicine, but information is limited for veterinary practice.

OBJECTIVE

To characterize antimicrobial use in horses undergoing emergency colic surgery.

ANIMALS

A total of 761 horses undergoing emergency colic surgery (2001-2007).

METHODS

Retrospective case review. Antimicrobial dose and timing, surgical description, and duration of treatment were collected from medical records. Associations between antimicrobial use and the occurrence of fever, incisional inflammation or infection, catheter-associated complications, or Salmonella shedding during hospitalization were analyzed using rank-sum methods and logistic regression.

RESULTS

A total of 511 (67.2%) horses received an inappropriate amount of drug preoperatively. Median time from preoperative dose to incision was 70 (IQR 55-90) minutes; median total surgery time was 110 (IQR 80-160) minutes. Seventy-three horses were euthanized under anesthesia because of poor prognosis. Of 688 horses, 438 should have been redosed intraoperatively based on the duration of surgery. Only 8 (1.8%) horses were redosed correctly. Horses remained on perioperative antimicrobials a median of 3 (IQR 2-4.5) days. Antimicrobial therapy was reinstituted in 193 (28.9%) horses, and median days of total treatment were 3.8 (IQR 2-6). Signs that led to reinstituting therapy were fever (OR 3.13, P = .001) and incisional inflammation/infection (OR 2.95, P = .001). Horses in which treatment was reinstituted had 2.3 greater odds of shedding Salmonella (P = .003). Increased surgical time was associated with longer duration of antimicrobial therapy (OR 1.02, P = .001).

CONCLUSIONS AND CLINICAL RELEVANCE

Despite published recommendations regarding antimicrobial prophylaxis, compliance is poor; improvement might reduce postoperative complications.

Principles of antimicrobial therapy: what should we be using?

Although the use of antimicrobials has had an insurmountable impact on preventing patient morbidity and mortality, problems with antimicrobial resistance and antimicrobial-induced diarrhea are becoming more apparent in human and veterinary medicine. The mortality associated with nosocomial infection with antimicrobial-resistant bacteria in human patients is alarming. Similarly, in veterinary medicine, the morbidity and high cost of treatment of patients with postoperative infection, for example, are concerns. Specifically in equine medicine, the high morbidity and mortality associated with antimicrobial-induced diarrhea have been devastating in many equine practices. Misuse of antimicrobials is extremely common in human and veterinary medicine. All clinicians have the responsibility to consider the appropriateness of their antimicrobial use carefully and, whenever possible, to minimize antimicrobial administration to patients.

Penicillins for the prophylaxis of bacterial endocarditis in dentistry

BACKGROUND

Many dental procedures cause bacteraemia and it is believed that this may lead to bacterial endocarditis (BE) in a few people. Guidelines in many countries recommend that prior to invasive dental procedures antibiotics are administered to people at high risk of endocarditis. However, it is unclear whether the potential risks of this prophylaxis outweigh the potential benefits.

OBJECTIVES

To determine whether prophylactic penicillin administration compared to no such administration or placebo before invasive dental procedures in people at increased risk of BE influences mortality, serious illness or endocarditis incidence.

SEARCH STRATEGY

The search strategy was developed on MEDLINE and adapted for use on the Cochrane Oral Health, Heart and Infectious Diseases Groups' Trials Registers (to October 2003), as well as the following databases: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2002), OLDMEDLINE (1966 to June 2002); EMBASE (1980 to June 2002); SIGLE (to June 2002); and the Meta-register of current controlled trials.

SELECTION CRITERIA

Due to the low incidence of BE it was anticipated that few if any trials would be located. For this reason, cohort and case controlled studies were included where suitably matched control or comparison groups had been studied. The intervention was the administration of penicillin compared to no such administration before a dental procedure in people with an increased risk of BE. Cohort studies would need to follow those at increased risk and assess outcomes following any invasive dental procedures, grouping by whether prophylaxis was received. Included case control studies would need to match people who had developed endocarditis (and who were known to be at increased risk before undergoing an invasive dental procedure preceding the onset of endocarditis) with those at similar risk but who had not developed endocarditis. Outcomes of interest were: mortality or serious adverse event requiring hospital admission; development of endocarditis following any dental procedure in a defined time period; development of endocarditis due to other non-dental causes; any recorded adverse events to the antibiotics; and cost implications of the antibiotic provision for the care of those patients who develop endocarditis.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected studies for inclusion, then assessed quality and extracted data from the included study.

MAIN RESULTS

No RCTs, CCTs or cohort studies were included. One case-control study met the inclusion criteria. It collected all the cases of endocarditis in the Netherlands over 2 years, finding a total of 24 people who developed endocarditis within 180 days of an invasive dental procedure, definitely requiring prophylaxis according to current guidelines and who were at increased risk of endocarditis due to a pre-existing cardiac problem. This study included participants who died because of the endocarditis (using proxys). Controls attended local cardiology outpatient clinics for similar cardiac problems, had undergone an invasive dental procedure within the past 180 days and were matched by age with the cases. No significant effect of penicillin prophylaxis on the incidence of endocarditis could be seen. No data were found on other outcomes.

REVIEWERS' CONCLUSIONS

There is no evidence about whether penicillin prophylaxis is effective or ineffective against bacterial endocarditis in people at risk who are about to undergo an invasive dental procedure. There is a lack of evidence to support published guidelines in this area. It is not clear whether the potential harms and costs of penicillin administration outweigh any beneficial effect. Ethically practitioners need to discuss the potential benefits and harms of antibiotic prophylaxis with their patients before a decision is made about administration.

Pharmacokinetics and tissue distribution of intravenous pefloxacin for antibiotic prophylaxis in biliary surgery

The plasma levels and tissue penetration of pefloxacin were studied after prophylactic administration to patients undergoing elective biliary surgery. Pefloxacin was administered as a single dose of 800 mg given intravenously as an infusion 1 h before surgery. Over a period of two years, cultures of bile and stone were performed after cholecystectomy in order to find the main pathogens present in the geographical area of the hospital of Txagorritxu (Vitoria, Spain), as well as to test the antimicrobial susceptibility of these bacteria to pefloxacin. Thirty seven per cent of the bile and stone cultures were positive, and 75 different species were isolated. E. coli was the predominant microorganism (25%). Other frequent microorganisms were E. faecium (9.3%), S. epidermidis (6.6%) and Cl. perfringens (6.6%). Most species isolated were susceptible to pefloxacin, with MIC(90) values of 0.125 microg/ml for E. coli, 0.5 microg/ml for S. epidermidis and 1 microg/ml for Cl. perfringens. E. faecium was resistant, with a MIC(90) value of 8 microg/ml but a MIC(50) of 4 microg/ml (intermediate). After pefloxacin infusion, adequate drug plasma levels (>MIC(90)) for the most frequent pathogens were found throughout the procedure. Elimination half-life was estimated as 22.03+/-6.91 h; the area under the concentration-time curve from zero to infinite had a value of 275.07+/-130.02 mg h/l and the values for volume of distribution at steady-state and plasma clearance were 96.48+/-28.65 L and 3.60+/-1.83 l/h, respectively. Bile pefloxacin concentrations generally exceeded the minimum inhibitory concentrations for most relevant pathogens. Drug levels in gallbladder and subcutaneous tissues were also above the MIC(90) for extended periods. Patients were observed daily throughout their hospital stay. This included examination of the surgical wound and recording of body temperature. No cases of anaerobic infection were noted in the study patients. Other constants such as hospitalization stay and time of recuperation were normal for this type of surgery. According to these results, pefloxacin presents many features that make it suitable for use as a therapeutic prophylactic agent, such as its broad spectrum of antimicrobial activity and favorable pharmacokinetic properties.

Preoperative antimicrobial prophylaxis with a long-acting cephalosporin for thoracic surgery in 192 non small cell lung cancer patients

The efficacy of preoperative antibiotic prophylaxis in thoracic surgery with a single dose of ceftriaxone was investigated. Here we report the results of a prospective study including 192 patients undergoing thoracic surgery for non small cell lung cancer. Overall, the postoperative infection rate, as measured by wound, respiratory tract, and urinary tract infections, was 8.3% (16/192). Ceftriaxone was well tolerated, and no allergic or other adverse reactions were reported. A single preoperative dose of ceftriaxone was cost-effective and allowed considerable saving of time, material, labor costs and money. This study, even though open and non-comparative, suggests that the routine use of a single preoperative dose of ceftriaxone provides a cost-effective prophylaxis for patients undergoing major thoracic operations.

Antibiotics for the acute abdomen

Antibiotics are only an adjunct to proper surgical therapy for the treatment of the acute abdomen associated with bacterial secondary peritonitis. Upon presentation, all patients require a preoperative dose of antibiotics for prophylaxis against infection of remaining sterile tissues. Patients found intraoperatively to have an established peritoneal infection benefit from an immediate postoperative course of therapeutic antibiotics. A regimen that adequately covers facultative and aerobic gram-negative bacilli and anaerobic organisms is essential. The duration of therapeutic antibiotics is probably best decided on an individual patient basis. The goal of antibiotics is to reduce the concentration of bacteria invading tissues. The pathogens of bacterial peritonitis are influenced by such factors as the patient's pre-existing chronic diseases, state of acute physiologic debilitation, immunocompetence, recent antibiotic use, recent hospitalization, and neutralization of gastric acidity. Intraoperative peritoneal cultures are most useful in patients suspected of having impaired local host defenses. In these patients, all identified organisms, such as Enterococcus or Candida, may be potential pathogens. The common practice of administering empiric and prolonged courses of broad-spectrum antibiotics in patients who manifest persistent signs of inflammation may be more harmful than beneficial. These patients warrant an exhaustive search for extra-abdominal and intraperitoneal sources of new infection. Otherwise, such use of antibiotics may continue to promote the selection of bacteria that are highly resistant to conventional antibiotics and permit the overgrowth of organisms commonly seen with tertiary peritonitis. The best chance of resolving bacterial peritonitis is through early, aggressive surgical management complemented by short courses of potent antibiotics and appropriate physiologic support. Through these efforts, the clinician tries to help the systemic inflammatory response to benefit the host and not become unregulated, result in MOFS, and produce a high mortality.

Antibiotic therapy and the anesthesiologist

The anesthesiologist is frequently responsible for administering antibiotics in the immediate preoperative and intraoperative periods. Anesthesiologists often are not trained in the administration of antibiotics, which can be associated with both acute and long-term complications including potentiation of neuromuscular blocking agents, allergic reactions, and end-organ toxicity. The indications for perioperative antibiotics, proper method of administration, and occurrence and treatment of major side effects of the more commonly recommended prophylactic antibiotics are discussed.

Prospective randomized trial of mechanical bowel preparation in patients undergoing elective colorectal surgery

A total of 149 patients admitted for elective colorectal surgery were randomly allocated to receive preoperative mechanical bowel preparation (group 1) or no mechanical bowel preparation (group 2). All patients received antimicrobial prophylaxis with cephalothin and metronidazole. The overall incidence of wound infection was 17.4 per cent (24 per cent for group 1, 12 per cent for group 2) and that of dehiscence 7.4 per cent (10 per cent for group 1, 5 per cent for group 2). The incidence of wound infection was significantly higher in group 1 (P < 0.05) but that of anastomotic dehiscence did not differ significantly between groups. Mechanical bowel preparation is unnecessary and may be harmful in terms of preventing wound infection and anastomotic dehiscence in patients undergoing elective colorectal surgery.

The timing of prophylactic administration of antibiotics and the risk of surgical-wound infection

BACKGROUND

Randomized, controlled trials have shown that prophylactic antibiotics are effective in preventing surgical-wound infections. However, it is uncertain how the timing of antibiotic administration affects the risk of surgical-wound infection in actual clinical practice.

METHODS

We prospectively monitored the timing of antibiotic prophylaxis and studied the occurrence of surgical-wound infections in 2847 patients undergoing elective clean or "clean-contaminated" surgical procedures at a large community hospital. The administration of antibiotics 2 to 24 hours before the surgical incision was defined as early; that during the 2 hours before the incision, as preoperative; that during the 3 hours after the incision, as perioperative; and that more than 3 but less than 24 hours after the incision, as postoperative.

RESULTS

Of the 1708 patients who received the prophylactic antibiotics preoperatively, 10 (0.6 percent) subsequently had surgical-wound infections. Of the 282 patients who received the antibiotics perioperatively, 4 (1.4 percent) had such infections (P = 0.12; relative risk as compared with the preoperatively treated group, 2.4; 95 percent confidence interval, 0.9 to 7.9). Of 488 patients who received the antibiotics postoperatively, 16 (3.3 percent) had wound infections (P less than 0.0001; relative risk, 5.8; 95 percent confidence interval, 2.6 to 12.3). Finally, of 369 patients who had antibiotics administered early, 14 (3.8 percent) had wound infections (P less than 0.0001; relative risk, 6.7; 95 percent confidence interval, 2.9 to 14.7). Stepwise logistic-regression analysis confirmed that the administration of antibiotics in the preoperative period was associated with the lowest risk of surgical-wound infection.

CONCLUSIONS

We conclude that in surgical practice there is considerable variation in the timing of prophylactic administration of antibiotics and that administration in the two hours before surgery reduces the risk of wound infection.

Role of quinolones in surgical prophylaxis

The general principles involved in the use of chemoprophylaxis in surgery, the selection of patients at risk, and the choice of antibiotic agents are reasonably well established. While a good deal of data exist regarding commonly used prophylactic regimens, very little data are available on the role of quinolones in surgical prophylaxis. The literature dealing with this area is reviewed, and studies on the use of quinolones in biliary, colorectal, urologic, orthopedic and vascular surgery are discussed. The data suggest that generally the quinolones are as efficacious as the other antibiotics with which they were compared, and in the case of urologic surgery the results using quinolones were better than those in non-treated controls. Single-dose prophylaxis was regularly shown to be as effective as multiple dose regimens. Further clinical trial data are necessary before any firm conclusions can be drawn regarding the role of quinolones in surgical prophylaxis.

Perioperative medical care for equine abdominal surgery

Rational perioperative management improves the success rate of abdominal surgery. Important aspects of management are discussed, including principles of fluid therapy, nutrition, intravenous catheterization, antimicrobial prophylaxis, and the use of nonsteroidal anti-inflammatory medication. Current advances in the area of immunotherapy are mentioned.