Search

Within the framework of the Health Protection Agency's programme of enhanced surveillance of Staphylococcus aureus with Panton-Valentine Leucocidin (PVL-SA) in England and Wales conducted during 2005-2006, we identified 720 PVL-SA, representing a two-fold increase between 2005 (n = 224) and 2006 (n = 496). The number of PVL-methicillin-resistant S. aureus rose from 119 to 159 in that period. Isolates were referred by 112 centres and included outbreaks of PVL-related disease in community and healthcare settings. One hundred individuals had systemic disease symptoms. Planned systematic surveillance-based studies aim to better address the question of whether these increases reflect an increasing prevalence of PVL-SA and/or improved case ascertainment of PVL-related syndromes.

Raised epinephrine concentrations concentrations developed in the blood of mice near death after an intraperitoneal challenge with 10(9) Staphylococcus aureus or Escherichia coli. Both epinephrine levels were elevated in the urine near death. These challenges were infections and not intoxications, as they could be successfully treated with antibiotics. Using the same model infections, we studied the effect of alpha-and beta-receptor blocking agents and other adrenergically active compounds. The compounds alone were not toxic in the doses used. alpha-Blockers, such as phenoxybenzamine, dibenamine, and ergotamine and beta-blockers, such as butoxamine, timolol, and practolol, were ineffective. Phentolamine alone or propranolol alone showed some evidence of an ability to prolong life in S. aureus infections. Together they lengthened life significantly in S. aureus-challenged mice. In E. coli infections this beneficial effect was not noted. Mice pretreated with reserpine (7 mg/kg) and challenged with S. aureus lived 55% longer than saline-treated controls. Less benefit was noted in E. coli infections. Serontonin treatment was helpful in S. aureus infections and deleterious in E. coli infections.

Evidence has been sought for life-prolonging effects of a variety of chemicals given subcutaneously 1 hr after intraperitoneal challenge of mice with 10(9) Staphylococcus aureus cells. The chemicals were chosen to replace chemicals found to be missing in the blood or carcass at death or to treat biochemical or visible abnormalities in sick mice near death from infection. Nafcillin given subcutaneously in adequate amounts cure S. aureus infection. In these experiments nafcillin treatment was delayed until 40% of the time from challenge to death in the controls. Chemicals were given in addition to nafcillin subcutaneously 20% of the time from challenge to death. Cortisol, Dilantic, epsilon-aminocaproic acid, glucose, nicotinamide, olive oil, phentolamine-propanalol, sodium bicarbonate, sodium lactate, and reserpine each prolonged life compared to saline treatment. When nafcillin was added, only cortisol, Dilantin, nicotinamide and reserpine were found to prolong life significantly compared to nafcillin-saline treatment Fatality rates were significantly reduced with cortisol and Dilantin when they were given in association with nafcillin compared to nafcillin-saline treatment.

A radioisotope technique has been used to determine blood pressure changes in mice after lethal staphylococcal infection and after lethal endotoxin challenge. The method was verified by making simultaneous direct measurements in rats. Mice in both groups became hypotensive to a similar level (a fall 20-30 mm Hg). This tailcuff technique is simple and reliable but is dependent upon normal tail blood flow. Spurious low pressure readings are obtained in hypothermic or chilled mice because the tail is a major thermoregulator organ. These difficulties can be overcome by warming chilled or hypothermic mice.