The Bacterial Flora of Battle Wounds at the Time of Primary Débridement: A Study of the Korean Battle Casualty*
Lieutenant Colonel Robert B. Lindberg, MSC, USA
Theodore F. Wetzler, B. S.
Captain John D. Marshall, MSC, USA
Major Arthur Newton, MSC, USA
1st Lieutenant Joseph G. Strawitz. MC, USAR
Captain John M. Howard, MC, USAR
This study was carried out at the 46th Surgical Hospital (Mobile Army) on the eastern front in Korea during August and September of 1952 and from December through February of 1953. Its purpose was to describe the bacterial flora of the battle wound at the time of primary surgical intervention.
During the period of this study, the front lines in eastern Korea were stable; hence most casualties received immediate first aid. Large wounds were often covered with a sterile pad before the casualty was transported. At a battalion aid station, wounds were inspected by a medical officer and, when feasible, sterile dressings were applied to large wounds which had not been covered previously. Small wounds were bandaged unless they were too numerous or too widely distributed. From 300,000 to 600,000 units of penicillin and tetanus toxoid were administered routinely. When ambulance evacuation was used, patients were examined at collecting and clearing company levels prior to arrival at the surgical hospital.
The 46th Surgical Hospital was located approximately ten miles behind the front lines. Resuscitation was continued here for variable periods, depending upon the degree of blood loss and the number of casualties awaiting operation. Following resuscitation, the patient was moved to the operating room and anesthetized; and all bandages were removed.
*Previously published in Annals of Surgery 141: 369, 1955.
Wounds were prepared for débridernent by cleansing with a sterile sponge and by pouring a solution of green soap and then water over the wound. The surrounding skin was painted with tincture of merthiolate and covered with sterile towels. Intra-thoracic or intra-abdominal wounds were excluded from this study.
Tissue blocks from 0.5 to 1.0 cc.in size were then cut from the skin margins, subcutaneous tissue, and muscle. These were placed directly into a chopped heart-infusion medium (modified Robertson`s). The wounds were débrided, followed by irrigation with normal saline solution before applying dressings. Usually patients were held under observation for several days and given penicillin therapy. If their convalescence appeared uncomplicated, they were sent to the rear through regular evacuation channels.
The culture tubes were sealed with Vaseline; and within 5 to 7 days they were sent by air to the Bacteriology Department of the 406th Medical General Laboratory in Tokyo. Twenty control studies demonstrated that the inoculates remained viable when shipped in this manner.
Clostridial isolates were identified and pathogenicities verified by standard, guinea-pig inoculation.1 In vitro sensitivities of anaerobic isolates to Aureomycin, Terramycin, penicillin, and chloramphenicol were performed by the tube-dilution method.2 Aerobic organisms were isolated and identified by routine methods.
In a similar study made during the winter of 1952, 21 samples of soil were taken from bunkers on the main line of resistance, from areas forward of the line which were frequented by patrols, from shower points, and from other areas where troops might come in contact with soil. Skin swabs were made of 40 combat soldiers and 35 samples of clothing were taken from wounded troops. All of these were cultured in the manner described.
A summary of the anaerobic flora is given in Tables 1, 2, and 3. The wounds were tabulated according to size. Wounds of less than 1 cm. in diameter were listed as small; wounds from 1 to 5 cm. in diameter, medium; and wounds greater than 5 cm. in diameter, large.
Table 1 shows that the tissue blocks from 84 percent of all wounds studied during the summer contained clostridia; and 44 percent contained pathogenic clostridia. There was no significant correlation between the bacterial flora and the time lag from injury to biopsy; but the larger wounds had a much higher incidence of pathogenic clostridia.
Table1. The Anaerobic Flora of Tissue Blocks Taken from 42 Wounds of 33 Patients-Summer 1952
Table2. The Anaerobic Flora of Tissue Blocks Taken from 112 Wounds of 69 Patients-Winter 1952-1953
Table 2 shows that tissue blocks from 36 percent of all wounds studied during the winter contained clostridia. In this group of patients, the size of the wound did not appear to be related to the incidence of contamination by clostridia. As in the earlier study, there did not appear to be a significant correlation between the presence of clostridia and the time lag from injury to surgery.
A comparison of these two studies showed that a significantly higher percentage of wounds examined during the summer contained clostridia than did those examined during the winter. The time lag between injury and surgery, however, was somewhat greater in the winter than in the summer.
Tabulation is made by species of the distribution of clostridia in wounds, on the skin and clothing, and in the soil (Table 3). The summer series showed an average of 2.3 strains per wound, while for the winter series it was 1.5 strains per wound.
Table3. Distribution of Clostridial Species in Wounds, Skin, Clothing, and Soil
Pathogenicity of Clostridia
The following organisms were found to be pathogenic in guinea pigs: Cl. perfringens, Cl. carnis, Cl. chauvoei, Cl. septicum, Cl. novyi, Ci. sordelli, Cl. histolyticum, Cl. tetani, Cl. difficile, Cl. parabotulinum, and Cl. fallax. This pathogenicity compared favorably with those described in the literature.3
Tables 4 and 5 show that sensitivities of 126 clostridial isolates to penicillin, Aureomycin, Terramycin, and chloramphenicol followed normal-distribution curves. Aureomycin and Terramycin appear to be inhibitory in the lowest concentrations. Those concentrations were omitted which were not inhibitory.
The aerobic organisms isolated from the wounds (Table 6) were those commonly found in soil, air, organic matter, and in the respiratory tracts of medical personnel. The tissue blocks from 89 percent of the wounds cultured during the summer contained pathogenic and nonpathogenic aerobes; and 81 percent of those cultured in the winter were positive for aerobes. Strains of staphylococcus and streptococcus were found more frequently during the winter months, while thecolon group of organisms were found more frequently in summer. The size of the wound did not appear to influence the presence or absence of aerobic organisms.
The data presented confirm the belief that a large percentage of battle wounds contain pathogenic aerobes and anaerobes. It is likely that the actual incidence of simple contamination may be higher than presented here, since only isolated blocks from representative portions of any single wound were cultured. It is entirely probable that a considerable number of organisms were missed by this method of examination.
The strikingly lower incidence of clostridial contamination in wounds during the winter months may have resulted from a decrease in the clostridial population found in the environment. Moisture and organic matter are factors necessary for clostridial proliferation.4 With freezing temperatures, these growth factors were not. present and bacteria remained dormant. Furthermore, direct contact. of the troops with the soil may be diminished when the terrain is frozen and covered with ice and snow.
The importance of the presence of aerobes in 89 percent of wounds which occurred during the summer and 81 percent during the winter cannot be minimized. Not only do these organisms have the ability
Table4. Sensitivities of 126 Clostridial Isolates to Penicillin And Aureomycin
Table5. Sensitivities of 126 Clostridial Isolates to Terramycin and Chloramphenical
Table 6. Distribution of Aerobes in Wounds
to produce severe infections, but they may have an influence on the proliferation or inhibition of other pathogenic aerobes present which must not be overlooked.4 The complex nature of symbiotic relationships between bacteria in wounds requires further investigation. The presence of pathogenic aerobes and anaerobes in both small and large wounds re-emphasizs the possiblity of severe infedtions resulting from the delay in treatment or improper surgical management. The higher inceidence of strains of streptococcus and staphylococus in wounds occurring in the winter may result from the prevalence of upper respiratory infections during this season. The greater frequency of the colon group of organisms seen in wounds occurring in the summer might be explained by the fact that the soil in Korea is fertilized with raw human excrement; and these organisms tend to proliferate in the absence of freezing temperatures.
In vitro sensitivity studies of clostridial isolates to various antibiotics show that lower concentrations of Aureomycin and Terramycin than of penicillin are abe to inhibit growth During the Korean conflict, penicillin was used almost exclusively for prophylaxis of wound infections. Perhaps the re-evaluation of antibiotic therapy after battle injury would lead to a more extensive use of the newer antibiotics.
Similar studies from World War I and World War II have appeared in the literature.5-8 All these studies confirmed the presence
of pathogenic aerobes and anaerobes in wounds prior to initial surgery. Clostridia were usually found in 40 to 50 percent of wounds, and aerobes in 80 to 90 percent. Despite the high incidence of simple contamination, the actual occurrence of gas gangrene was strikingly low in most studies. During World War I, Gross and co-workers reported an incidence of 1.9 percent and 3 percent in several series including large numbers of wounded soldiers.9 During World War II, MacLennan reported anaerobic cellulitis occurring in 1 percent of the wounded soldiers and obvious gas gangrene in from 0.32 to 0.7 percent.7 Other reviews suggest that there was little difference in the incidence of serious wound infections between the two world wars.10 It appears that, with early and complete débridement of devitalized tissue and use of antibiotics, the occurrence of serious wound infections was lower during World War II.
In a study carried on during the latter phase of the Korean conflict, Howard and Inui found that the incidence of gas gangrene in 4,900 casualties dropped to 0.08 per cent and mortality to zero. 11 This decreased incidence of severe clostridial infection was not due to a decrease in contamination of wounds with pathogenic organisms. It probably resulted from earlier débridement, repair of arterial injuries, and the consistent use of antibiotics.
1. A large percentage of the battle wounds examined within 8 hours after injury contained pathogenic aerobes and anaerobes as contaminants.
2. A smaller percentage of wounds showed contamination during the winter than do those cultured during the summer.
3. In vitro sensitivity studies of clostridial isolates to various antibiotics showed that the antibiotics, Aureomycin and Terramycin, were able to inhibit growth in the lowest concentrations.
1. Reed, G. B., and Orr, J. M.: Rapid Identification of Gas Gangrene Anaerobes. War Medicine, 1: 493, 1941.
2. Newton. A.; Strawitz, J. G.: Lindherg, R. B.; and Howard. J. M.: Sensitivities of Ten Species of Clostridia to Penicillin, Aureomycin, Terramycin, and Chloramphenicol. (Chapter 16 of this volume.)
3. Breed, Robert S.; Murray, F.G. D.; and Hitchens, A. P.: Bergey`s Manual of Determinative Bacteriology, 6th ed. Williams and Wilkins Company, Baltimore, Maryland, 1948.
4. Ireland, M. W.; Callender, G.R.; and Coupal, J. F.: Pathology of Gas Gangrene Following War Wounds, Sec. II, pp. 407-567, The Medical Department of the United States Army in the World War, Vol. XII. U.S. Government Printing Office, Washington, D. C., 1929.
5. Stoddard, J. L.: The Occurrence and Significance of B. welchii in Certain Wounds. J. A. M. A. 71: 1400, 1918.
6. MacLennan, J. D.: Anaerobic Infections of War Wounds in the Middle East. Lancet 245: 123 (July 31), 1943.
7. MacLennan, J. D.: Anaerobic Infections in Tripolitania and Tunisia. Lancet 246: 203 (Feb. 12), 1944.
8. Rustigian, R., and Cipriani, A.: The Bacteriology of Open Wounds. J. A. M. A. 133: 224, 1947.
9. Gross, Sieru, Mercier, and Lardenois: Treatment of Gas Bacillus Infection. Cited by Van Bouran.
10.Smith, L. D.: Clostridia in Gas Gangrene. Bacteriological Reviews 13: 233, 1949.
11.Howard, J. M., and Inui, F. K.: Clostridial Myositis-Gas Gangrene: Observations of Battle Casualties in Korea. Surgery 36: 1115, 1954. (Chapter 15 of this volume.)