Number Of Aerobic Organisms Research Articles

One-dose antibiotic prophylaxis against wound infection after appendicectomy: A randomized trial of clindamycin, cefazolin sodium and a placebo

Two hundred and fifty patients were admitted to a prospective randomized trial of single dosage prophylaxis against wound infection after appendicectomy. There were 12 exclusions, 72 patients received placebo, 81 received 600 mg i.m. clindamycin phosphate and 85 received 1 1 g i.m. cefazolin sodium, the agent being given in the anaesthetic room. Clindamycin produced a significant reduction in the overall rate of wound infection from 33 per cent in the controls to 17 per cent. In cases with a gangrenous or perforated appendix the infection rate in controls was 78 per cent; this was reduced to 44 per cent by a single dose of clindamycin. Cefazolin significantly reduced the number of aerobic organisms isolated from wound infections, but did not significantly reduce the incidence of wound infection. We conclude that anaerobic organisms are more important than faecal aerobic organisms in the pathogenesis of wound infection after appendicectomy.

Effects of High-Energy Electron Irradiation of Chicken Meat on Salmonella and Aerobic Plate Count

Four experiments were used to determine the effects of high-energy irradiation on the number of aerobic microorganisms and Salmonella on broiler breasts and thighs. Irradiation ranging from 100 to 700 kilorads (krads) was provided by a commercial-scale, electron-beam accelerator. Irradiation of broiler breast and thigh pieces with electron beams at levels of 100, 200, 300, 400, 500, and 600 krads showed that levels as low as 100 krads would eliminate Salmonella. When 33 thighs were tested after irradiation at 200 krads, only one thigh tested presumptive positive. The total number of aerobic organisms was reduced by 2 to 3 log10 cycles at irradiation levels of 100, 200, 300, 400, 500, 600, and 700 krads. Increasing the dose above 100 krads gave little if any additional benefit.

Effect of antimicrobial therapy on bowel flora and bacterial infection in irradiated mice.

Mice exposed to 10 Gy cobalt-60 radiation were given intramuscular antimicrobial therapy of gentamicin, or metronidazole, or a combination of the two. Mortality in the mice treated with metronidazole alone or in combination with gentamicin occurred earlier than in the controls (P less than 0.001). Microorganisms were recovered from the blood, spleen, and liver of the metronidazole-treated mice earlier than from other groups. The predominant organisms recovered from these animals were Enterobacteriaceae. Quantitative cultures of the ileal flora showed a decrease in the number of aerobic, facultative anaerobic and strict anaerobic bacteria after irradiation, and a subsequent increase only in the number of strict aerobic bacteria. As compared to untreated mice, a rapid decrease (by 8.8 logs) in the number of anaerobic flora occurred in the mice treated with metronidazole 5 days after irradiation. This was followed by a rapid increase in the number of aerobic organisms which coincided with the earlier mortality in this group. These data suggest that antimicrobial agents that decrease the number of the strict anaerobic component of the gut flora enhance systemic infection by aerobic or facultative anaerobic bacteria, and this facilitates mortality after irradiation.

The role of gastrointestinal microflora in the pathogenesis of complications of mesenteric ischemia.

Mesenteric ischemia is a catastrophic event, which has a mortality due to florid sepsis that approaches 100%. The demography of the bacterial changes has not been documented. After 72 hr of colonic ischemia in the dog, the total number of anaerobic organisms increased while the number of aerobic organisms decreased. After 24 hr of ischemia, anaerobic bacteria appeared only in the portal vein and persisted. Cultures of peritoneal fluid and aortic blood became positive for the same anaerobic organisms after 48 hr. Acute colonic ischemia promotes a relative overgrowth of intraluminal anaerobic bacteria, which progressively invade the portal vein and later the systemic circulation.