A bacteriological study of the immediate environment of a surgical wound

Effect of Preoperative Shampoos with Chlorhexidine or lodophor on Emergence of Resident Scalp Flora in Neurosurgery

Wound contamination with endogenous bacterial scalp flora plays an important role in the pathogenesis of postoperative neurosurgical infections. To assess the effect of preoperative antiseptic shampoos on the emergence of resident scalp flora during surgery and subsequent wound contamination, we randomized 151 neurosurgical procedures into four study groups: group A—preoperative shampoos with chlorhexidine, surgical scalp preparation with chlorhexidine; group B-no shampoos, surgical preparation with chlorhexidine; group C-shampoos with iodophor, surgical preparation with iodophor; group D-no shampoos, surgical preparation with iodophor. Quantitative cultures of the scalp were obtained preoperatively and at the end of surgery, and qualitative wound cultures were taken prior to wound closure. Group A had the lowest concentration of bacteria on the scalp both preoperatively and postoperatively (median range = 30 [0-5.7 × 105] and 0 [0-2.5 x 103] respectively). Group A also had significantly fewer positive postoperative scalp cultures (29%) than groups B (51%), C (58%), and D (53%) (P<0.05), as well as fewer positive wound cultures (20% v 25%, 42%, and 30% respectively). A density of bacteria on the scalp of > 102/4cm2 best predicted the presence of bacteria in the wound. Repeated preoperative shampoos with chlorhexidine reduce intraoperative emergence of resident skin flora and subsequent contamination of the wound.

Surgical-site infections and routes of bacterial transfer: which ones are most plausible?

BACKGROUND

Surgical-site infections (SSIs) are an unfortunate consequence of cutaneous surgery. Their incidence can be a significant problem for patients and surgeons. Most SSIs are presumed to originate from the patient and operating room staff.

OBJECTIVES

To review the potential routes of iatrogenic bacterial transfer during cutaneous surgery.

METHODS

A review of the medical literature.

CONCLUSIONS

Potential routes of bacterial transfer during surgery include respiratory droplets and nuclei, skin scales carried on air currents, direct contact with the surgical team's skin, and contaminated fomites. The route with the most significant potential for iatrogenic bacterial transfer is direct physical contact. Strategies that minimize contact with infected fomites and with the surgical team would probably have the best chances of reducing the incidence of SSIs.

Comparison of bacterial counts in glove juice of surgeons wearing smooth band rings versus those without rings

BACKGROUND

Removal of rings is recommended before surgeons aseptically prepare for surgical procedures.

OBJECTIVES

This study was undertaken to determine whether there is a difference between bacterial counts under surgical gloves of ring wearers compared with nonring wearers after proper aseptic hand preparation and 3 hours of wear.

METHODS

Twenty volunteer veterinary medical students were divided into 2 groups: One group wore a smooth ring band (without projections or mounted stones) on their ring finger, and the other group did not wear a ring. A modified glove juice method was used to obtain bacterial counts (colony-forming units/mL) inside surgically gloved hands prior to a proper aseptic hand preparation and 3 hours after hand preparation and wear. Each of the pre- and postsurgical glove juice samples were inoculated onto Letheen agar plates, which were incubated aerobically under atmospheric conditions for 48 hours at 35 degrees C. Gloves were tested for perforations using a water pressure test.

RESULTS

No differences, or significant change, in bacterial counts were found before or after surgery between all ring hands and nonring hands or between ring and nonring hands for ringed participants. No differences in bacterial counts were found within perforated versus nonperforated gloves.

CONCLUSION

There is no compelling evidence to suggest that surgeons wearing rings possess higher bacterial counts under their gloves during surgery.

Bacteriology of abdominal wounds in elective open colon surgery: a prospective study of 100 surgical wounds

This article describes a prospective bacteriological study designed to assess the value of bacterial sampling during elective open colon surgery. Swabs of the subcutaneous tissue were taken after closure of the abdominal fascia, but before closure of the skin, in 100 patients during elective colon surgery. Of the 100 swabs, 52 were sterile with no resulting wound infection, while ten of the remaining 48 contaminated swabs were associated with a wound infection caused by colonic pathogens and nosocomial microorganisms. Bacterial sampling seems to be a useful method for the prediction of wound infection following elective colon surgery.

Prophylactic antibiotics in patients undergoing laser resurfacing of the skin

BACKGROUND

Carbon dioxide (CO2) laser resurfacing produces a superficial second-degree burn that needs to be protected from bacterial and fungal infections.

OBJECTIVE

We investigated the effects of various systemic and topical antimicrobial regimens.

METHODS

Four different regimens using oral ciprofloxacin, topical antibiotics (intranasal mupirocin ointment and otic solution), oral ketoconazole, and oral fluconazole were tested in four time periods. The frequency and types of the infections with various regimens was compared.

RESULTS

The study included 356 sequential patients who underwent facial CO2 laser resurfacing. Infections occurred in 27 patients (7.6%). Without antibiotic prophylaxis, 8.2% of patients had bacterial infections from days 3 to 12 after the procedure (average, day 5). With prophylactic ciprofloxacin only, 4.3% of patients had bacterial infections; these occurred almost exclusively after ciprofloxacin was discontinued. For 7 months, patients were randomly assigned to either receive or not receive mupirocin intranasally. All Staphylococcus aureus infections that occurred were seen in patients who had used intranasal mupirocin. Yeast infections were seen in 6 patients (1.7%), but mostly occurred more than 10 days after the procedure. Yeast infections were of approximately equal occurrence in the ciprofloxacin group (2.2%) and in the non-ciprofloxacin group (1.8%). No yeast infections occurred in patients who had undergone antifungal prophylaxis.

CONCLUSION

Post-CO2 resurfacing infections are not rare but can appear subtly and might only be noticeable in the second postoperative week. Prophylactic intranasal mupirocin is ineffective, but ciprofloxacin is effective in preventing infection with both gram-positive and gram-negative bacteria. Oral ketoconazole and fluconazole are effective in preventing yeast infections.

Post-operative wound infections in Belize

The incidence of post-operative wound infections in Belize in 1986 and 1987 was studied. Both military practice in the military hospital and civilian practice in the rural hospitals of the local towns were included. Despite previous misgivings and sub-optimal conditions in the rural hospitals an acceptably low incidence was found in both areas of work.

Surgical glove perforation

In a study to investigate the incidence and significance of surgical glove perforation, bacterial contamination of surgeons' hands and gloves before and after operation was measured and the gloves tested for damage. Perforations were found in 74 of 582 gloves (12.7 per cent) and occurred in 34.5 per cent of operations. Glove perforation did not influence bacterial counts on the surgeons' hands or on the outside of their gloves. A separate clinical study of 100 adult hernia repairs gave no evidence that perforation increased wound sepsis. After standard pre-operative hand preparation, glove perforations are of no clinical significance to the patient, but their high incidence should alert surgeons to the need for protection against pathogens transmissible during surgery, such as hepatitis B and the human immunodeficiency virus. Protection of the surgeon is the main indication for preoperative change of damaged gloves.

Influence of surgeons' experience on postoperative sepsis

A prospective study was performed on 635 patients with appendicitis operated on by 7 trainees and 119 patients operated on by 6 senior surgeons with more than 8 years of surgical experience. In patients with normal appendices, postoperative sepsis was extremely low. For early and late appendicitis, the infection rates of the trainees decreased as experiences accumulated, but they were still higher than that of the senior surgeons. The difference in infection rates in acute appendicitis did not reach statistical significance between any of the training stages and between the various stages and the rate of the senior surgeons. The differences in infection rates in late appendicitis between stage 1 and stage 3 was significant, as was the difference in infection rates between stage 1 and the infection rate of the senior surgeons. Therefore, we have concluded that overall, the limited experience of trainees is related to the rate of postoperative sepsis in late appendicitis, although the infection rates of individual trainees vary a lot.

Airborne contamination during cardiopulmonary bypass: the role of cardiotomy suction

Airborne contamination of the wound area and the cardiopulmonary bypass circuit during sham open-heart operations on dogs was studied. The air of the operating room (OR) was contaminated with two typeable bacterial strains. It was found that the number of wounds, blood specimens, oxygenators, and cardiotomy reservoirs contaminated with Staphylococcus aureus was related to the number of S. aureus present in the air of the OR, but that contamination with Serratia marcescens was related to the type of suction used. This form of contamination was considerably higher when air was aspirated together with blood into the suction line (p less than 0.05). The oxygenator and cardiotomy reservoir were contaminated mainly by aspirating wound fluid from the airborne-contaminated wound area. The low number of sample sites positive for S. marcescens may be due to a better preserved host defense mechanism if only wound fluid is sucked. A rather high incidence of postoperative infections occurred even in dogs operated on in an OR with a low level of airborne contamination.

Contamination of urological wounds by aerobic bacteria. Transvesical prostatectomy used as a model

The density of aerobic bacteria in the subcutaneous wound was quantified by the velvet pad rinse technique before (first stage) and after (second stage) opening of the bladder in 13 patients undergoing transvesical prostatectomy. Six patients had bacteria in the urine preoperatively (group A) and the same bacteria were isolated from bladder puncture during the operation and during second stage. Seven patients (group B) had sterile urine preoperatively and the bacteria isolated during first and second stage were commensals of the skin and the upper-respiratory tract. The bacterial density in group B was median 3.1 viable counts (v.c.) x 10(-1)/cm2 during first stage rising to median 4.7 v.c. x 10-1/cm2 during second stage, while group A showed an increase from median 4.3 v.c. x 10(-1)/cm2 during first stage to median 169,5 v.c. x 10(-1)/cm2 during second stage. The results of the study indicate the possibility of using selective antibiotic prophylaxis, with the relevant antibiotic for the bacteria isolated in the urine preoperatively, to reduce postoperative wound infection in urological surgery with opening of the urinary bladder.

Primary postoperative wound infection due to Staphylococcus pyogenes

Using S. pyogenes as a tracer organism, an examination of the importance of air-borne infection of clean wounds in the modern, plenum-ventilated operating room has been made. It appears that, for most surgical procedures, additional ultra-clean air installations are not necessary. It has been shown that even if the air is sterile, the skin remains a possible source of infection. This is especially so as far as the patient's skin is concerned. It will remain so, since the skin cannot be sterilized. Indeed, until the ecology of the skin is better understood, rigorous efforts directed toward its disinfection may compromise its inherent defense mechanisms and its protective bacterial flora. It will be argued by some that operating rooms with ultraclean air should be afforded for certain specialized procedures in sugery; for example, those in which prosthetic materials are being implanted or in which the patient's immune mechanisms are depressed. Although not disagreeing with this, I wish to note that the only controlled trial on this aspect of surgery that exists to date shows no advantage for patients randomly apportioned to have hip arthroplasty, either in an isolator or in the same modern operating room but without the isolator. From this experience, I believe that any further trial of this nature, if it is to be controlled to a similar high level, will require very large numbers of patients to show even a marginal advantage for ultraclean air or isolator installations over the modern, plenum-ventilated and meticulously managed operating suite. The verdict on the need to install ultraclean air plant for operating rooms must, therefore, be couched in the third alternative that exists under Scots Law-- "not proved." I suggest the money could be better spent on devising methods to keep skin pathogens out of surgical wounds. Perhaps more urgently, there is a need to discover how to increase the defense mechanisms of the wound milieu to implanted harmful bacteria. There is also a pressing need to improve the ward environment with the aim of diminishing secondary infections of surgical wounds.

Disinfection of the skin of the abdomen

The skin of the abdomen of 106 staff and 358 patients was sampled 5 min and 2 h after disinfection using contact plates. Control areas of skin were treated with water only or left untreated. A reduction of 99 per cent (log reduction factor = 2) or more in colony counts was obtained in 5 min with 70 per cent ethyl alcohol and alcoholic solutions of chlorhexidine, povidone-iodine and chloroxylenol/EDTA. Aqueous solutions of chlorhexidine (0.5 per cent) Savlon (5 per cent), povidone-iodine (10 per cent) and chloroxylenol/EDTA (X10 recommended concentration) also showed similar reductions. Weaker aqueous solutions of chlorhexidine (0.05 per cent), Savlon (1 per cent) and chloroxylenol/EDTA (recommended concentration) were significantly less effective than the alcoholic and the most effective aqueous solutions, although all were more effective than water. Total bacterial counts were lower from the skin of female than from male staff and lower from staff than from patients. Pathogens (Staphylococcus aureus or Gram-negative bacilli) were isolated from only one member of staff in small numbers and irregularly and rarely in large numbers from patients. Few pathogens were isolated after application of any of the disinfectants.

Prevention of wound sepsis in gastro-intestinal surgery

After gastro-intestinal operations wound infection is usually caused by the inoculation of bacteria present within the intestinal tract into the incision during the surgical procedure. In theory, wound sepsis may be minimized by the following methods: (a) avoiding intestinal contamination of the incision; (b) altering the normal flora of the intestinal tract by adding oral antimicrobials to bowel preparation; (c) using topical or systemic prophylactic antibiotic administration for certain high-risk patients. The relative importance of these methods of prophylaxis is described.

A study of the effect of povidone-iodine on wound healing

The effect of dry powder povidone-iodine (Disadine D.P.) on wound healing was assessed experimentally and clinically. It did not interfere with wound healing macroscopically, histologically or mechanically in Wistar rats. One hundred and one patients undergoing 'clean' elective surgery were included in the controlled clinical study and povidone-iodine did not affect wound healing in any way. In the control group 4% of patients developed infection compared with none of those sprayed with povidone-iodine. No adverse reaction to povidone-iodine was seen in either study. This antiseptic offers a safe alternative to antibiotics for use at operation whenever there is risk of wound infection from operative bacterial contamination.

Chemoprophylaxis in surgery

The literature on the prophylactic use in surgery of disinfectants, antibiotics and the chemotherapeutic agents is reviewed. It is concluded that there is little place for the routine use of antibiotics or chemotherapeutic agents except in a very few conditions. Disinfectants do have a part to play in skin sterilization and in the reduction of postoperative wound infection. However, none of the compounds yet replaces careful technique and standard surgical procedure.

Single-dose peroperative antibiotic prophylaxis in gastrointestinal surgery

A single intravenous dose of tobramycin and lincomycin, given at the start of gastrointestinal operations, significantly reduced the incidence of postoperative wound infection from 34% to 5%. The occurrence of both anaerobic and aerobic bacteria was reduced. Therapeutic concentrations of the antibiotics were maintained throughout the operative period in most cases. No toxic effects of the antibiotics were detected, no anaesthetic complication occurred, and resistant strains of bacteria normally sensitive to the antibiotics were not isolated from wounds.

Postoperative wound infection after implant and removal of osteosynthetic material

Osteosynthetic material was implanted and removal in 972 consecutive operations in the upper and lower extremity. Early post-operative wound infection developed significantly more often after osteosynthesis than after removal of the implant; neither sex nor age influenced significantly the frequency of wound infection. The latter was higher when insertion or removal of material was performed in the lower extremity than in the upper extremity. The hip and ankle regions were involved most often. Staph. aureus and Staph. albus predominated among the Gram-positive infections; gram-negative infections, however, occurred remarkably frequently, E. coli being the most common organism isolated. To decimate exogenous and endogenous contamination of the wounds during operation, aseptic and antiseptic measures should be reinforced. In operation in a region proven to carry a higher post-operative infectious risk, i.e. the hip and ankle, it is suggested that antibiotics should be administered at the time of osteosynthesis.

Factors that influence surgical wound infections. Role of prophylactic antibiotic therapy

A comprehensive review of the factors responsible for postoperative wound sepsis is discussed, along with the experimental basis for the use of prophylatic antibiotics and a review of the results of the use of systemic and topical antibiotics on the incidence of surgical wound infections. Based on the data presented, suggestions are made which should minimize the development of postoperative wound infections.

A controlled trial of parenteral prophylactic gentamicin therapy in biliary surgery

This trial has investigated the value of gentamicin therapy in patients requiring biliary surgery. One hundred consecutive patients were randomly allocated to receive either gentamicin or no antibiotic. Post-operative infection was assessed by an independent observer. Cultures and gentamicin assays were performed on bile and blood sampled during and after operation. The minimum inhibitory concentrations of gentamicin were measured with isolated bacterial. In 80 per cent of patients biliary organisms were inhibited by 2 mug/ml of gentamicin. Twice this concentration was found in the serum at operation in 88 per cent, but in the bile in only 18 per cent. Nevertheless, gentamicin lowered the incidence of bacteria in the bile from 42 to 25 per cent. There was a reduction in wound sepsis from 21 to 6 per cent (P less than 0-05). Bacteriaemia was demonstrated in only 1 patient receiving gentamicin compared with 5 controls and 1 death occurred from endotoxaemia in the control group. These data suggest that gentamicin will reduce the morbidity of biliary surgery, particularly in patients in whom the bile is infected at operation.

Ward design in relation to postoperative wound infection: 3

The wound infection rates, nasal carriage rates, and nasal colonization rates were studied in a recently built surgical unit for two years when it was first opened. Five years later a further two-year period of study was undertaken.Judging by the incidence of postoperative wound infection, as far as both Staphylococcus pyogenes and Gram-negative organisms are concerned, there is no evidence that the environment has become less safe with use over the seven-year period since opening.

Disinfection of the umbilicus for abdominal surgery

Bacteriological investigation of the adult umbilicus showed that it is much more profusely colonised by bacteria than the rest of the abdominal skin. Routine preoperative treatment with alcoholic chlorhexidine solution did not disinfect the umbilicus satisfactorily. Better results were achieved by disinfection with povidone iodine followed by alcoholic chlorhexidine.

Postoperative wound infection: a computer analysis

Data believed to relate to the aetiology of postoperative wound infection were subjected to a computer analysis. Information was obtained from a total of 1000 patients and a multiple linear-regression analysis carried out. Five factors were found to be highly significant in determining the development of wound sepsis. These were a potentially dirty type of procedure, the presence of bacteria in the wound at the end of operation, one of the ward environments studied, the age of the patient, and the duration of the operation.