Monitoring Escherichia coli O157:H7 in inoculated and naturally colonized feedlot cattle and their environment.

On-farm methods of monitoring Escherichia coli O157:H7 were assessed in 30 experimentally inoculated steers housed in four pens over a 12-week period and in 202,878 naturally colonized feedlot cattle housed in 1,160 pens on four commercial Alberta feedlots over a 1-year period. In the challenge study, yearling steers were experimentally inoculated with 10(10) CFU of a four-strain mixture of nalidixic acid-resistant E. coli O157:H7. After inoculation, shedding of E. coli O157:H7 was monitored weekly by collecting rectal fecal samples (FEC), oral swabs (ORL), pooled fecal pats (PAT), manila ropes (ROP) orally accessed for 4 h, feed samples, water, and water bowl interface. Collection of FEC from all animals per pen provided superior isolation (P < 0.01) of E. coli O157:H7 compared with other methods, although labor and animal restraint requirements for fecal sample collection were high. When one sample was collected per pen of animals, E. coli O157:H7 was more likely to be detected from the ROP than from the FEC, PAT, or ORL (P < 0.001). In the commercial feedlot study, samples were limited to ROP and PAT, and E. coli O157:H7 was isolated in 18.8% of PAT and 6.8% of ROP samples. However, for animals that had been resident in the feedlot pen for at least 1 month, isolation of E. coli O157:H7 from ROP was not different from that from PAT (P = 0.35). Pens of animals on feed for <30 days were six times more likely to shed E. coli O157:H7 than were animals on feed for >30 days. However, change in diet did not affect shedding of the organism (P > 0.23) provided that animals had acclimated to the feedlot for 1 month or longer. Findings from this study indicate the importance of introduction of mitigation strategies early in the feeding period to reduce transference and the degree to which E. coli O157:H7 is shed into the environment.

[Causes of death in intensive care surgical patients. A prospective study]. / Todesursachen operativer Intensivpatienten. Eine prospektive Studie.

Infection and sepsis are generally considered as causally related to death in intensive care unit (ICU) patients, but in several studies a decrease in infection rates was not associated with lower mortality. We therefore investigated the causes of death in surgical ICU patients, with special regard to the relationship between infection and mortality. MATERIAL AND METHODS. During the investigation period of 6 months, 502 patients were treated in the ICU (cardiac surgery: 222, thoracoabdominal surgery: 125, vascular surgery: 84, others: 14). In all patients each antibiotic therapy and infection was documented, as was the sepsis score. Definitions of infection and bacteriological monitoring were described in detail previously. In all deaths, attention was paid to an infection that was causally related to or contributed to death. In unclear cases a postmortem examination was performed. RESULTS. Forty-two patients died (8.4%). During the first 4 days 23 patients died, 11 within 24 h, because of severe trauma with severe underlying disease (main reason for death: cardiac 30%, cerebral 32%). Infections were not significant in these patients. Nineteen patients suffered from 1 or more infections (total 30). They died after a median of 16 days. The leading cause of death was multiple organ failure. In 7 of these patients a life-threatening infection was the reason for admission and, later, death. In 8 patients a nosocomial infection was causally related to or contributed to death. In the 4 other patients a postmortem examination excluded an infection as being responsible for death. DISCUSSION. More than one-half of the deaths were caused by severe trauma or severe underlying disease. Nosocomial infections could only be related to death in 1.6% of the 502 treated ICU patients. The influence of new therapeutic regimens on infection and mortality can therefore only be investigated in multicenter trials.