Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes.

BACKGROUND: Vitamin C is an essential water-soluble nutrient which cannot be synthesised or stored by humans. It is a potent antioxidant with anti-inflammatory and immune-supportive roles. Previous research has indicated that vitamin C levels are depleted in critically ill patients. In this study we have assessed plasma vitamin C concentrations in critically ill patients relative to infection status (septic shock or non-septic) and level of inflammation (C-reactive protein concentrations). Vitamin C status was also assessed relative to daily enteral and parenteral intakes to determine if standard intensive care unit (ICU) nutritional support is adequate to meet the vitamin C needs of critically ill patients. METHODS: Forty-four critically ill patients (24 with septic shock, 17 non-septic, 3 uncategorised) were recruited from the Christchurch Hospital Intensive Care Unit. We measured concentrations of plasma vitamin C and a pro-inflammatory biomarker (C-reactive protein) daily over 4 days and calculated patients' daily vitamin C intake from the enteral or total parenteral nutrition they received. We compared plasma vitamin C and C-reactive protein concentrations between septic shock and non-septic patients over 4 days using a mixed effects statistical model, and we compared the vitamin C status of the critically ill patients with known vitamin C bioavailability data using a four-parameter log-logistic response model. RESULTS: Overall, the critically ill patients exhibited hypovitaminosis C (i.e., < 23 µmol/L), with a mean plasma vitamin C concentration of 17.8 ± 8.7 µmol/L; of these, one-third had vitamin C deficiency (i.e., < 11 µmol/L). Patients with hypovitaminosis C had elevated inflammation (C-reactive protein levels; P < 0.05). The patients with septic shock had lower vitamin C concentrations and higher C-reactive protein concentrations than the non-septic patients (P < 0.05). Nearly 40% of the septic shock patients were deficient in vitamin C, compared with 25% of the non-septic patients. These low vitamin C levels were apparent despite receiving recommended intakes via enteral and/or parenteral nutritional therapy (mean 125 mg/d). CONCLUSIONS: Critically ill patients have low vitamin C concentrations despite receiving standard ICU nutrition. Septic shock patients have significantly depleted vitamin C levels compared with non-septic patients, likely resulting from increased metabolism due to the enhanced inflammatory response observed in septic shock.

Urinalysis orders and yield among General Medicine patients: a single-centre's experience in New Zealand.

BACKGROUND: Urinalysis performed by dipstick testing is an aid to diagnosing urinary tract infections (UTI), and a tool in selecting patients who require urine culture and antibiotic treatment. Previous studies have demonstrated that UTI, especially in the elderly, are over-diagnosed and over-treated. We sought to study the pattern and yield of urinalysis and urine culture at our service in a tertiary institution. METHODS: A convenience sampling method was utilised to prospectively collect clinical data, through a pre-designed pro forma, from patients admitted to the General Medicine service at Christchurch Hospital between March and June 2016. RESULTS: The study included 395 patients, with a median age of 76 (range 15-100 years). The presence of urinary tract symptoms was documented in 94 patients (24%) and a non-specific syndrome of elevated temperature, confusion or subjective feverishness in 69 (17%). In symptomatic patients, 121 (74%) had a dipstick performed and 104 (86%) urine samples cultured. In the remaining patients, 181 (78%) had a dipstick performed and 81 (35%) had a urine sample sent for culture. CONCLUSIONS: We found a large number of urine dipsticks is being ordered unnecessarily in asymptomatic patients. A more useful test is urine microscopy and culture that is done on symptomatic patients only following careful clinical evaluation. Performing 'routine' urinalysis in patients presenting a wide variety of symptoms may lead to unnecessary urine cultures and treatment of asymptomatic bacteriuria. Efforts to reduce unnecessary tests and antibiotic treatment are a vital component of diagnostic stewardship programmes.

The dosing and monitoring of vancomycin: what is the best way forward?

We have evaluated the literature to review optimal dosing and monitoring of intravenous vancomycin in adults, in response to evolving understanding of targets associated with efficacy and toxicity. The area under the total concentration-time curve (0-24 h) divided by the minimum inhibitory concentration (AUC24/MIC) is the most commonly accepted index to guide vancomycin dosing for the treatment of Staphylococcus aureus infections, with a value of 400 h a widely recommended target for efficacy. Upper limits of AUC24 exposure of around 700 (mg/L).h have been proposed, based on the hypothesis that higher exposures of vancomycin are associated with an unacceptable risk of nephrotoxicity. If AUC24/MIC targets are used, sources of variability in the assessment of both AUC24 and MIC need to be considered. Current consensus guidelines recommend measuring trough vancomycin concentrations during intermittent dosing as a surrogate for the AUC24. Trough concentrations are a misleading surrogate for AUC24 and a poor end-point in themselves. AUC24 estimation using log-linear pharmacokinetic methods based on two plasma concentrations, or Bayesian methods are superior. Alternatively, a single concentration measured during continuous infusion allows simple AUC24 estimation and dose-adjustment. All of these methods have logistical challenges which must be overcome if they are to be adopted successfully.

Regulation of chicken contamination is urgently needed to control New Zealand's serious campylobacteriosis epidemic.

New Zealand's campylobacteriosis epidemic reached a new peak in May 2006 with the annualised national notification rate exceeding 400 per 100,000 for the first time, the highest national rate reported in the literature. The epidemic is estimated to cause at least 1 fatality a year, >800 hospitalisations, and >100,000 cases in the community, and cost the New Zealand economy 75 million dollars per annum. There is overwhelming epidemiological and laboratory evidence that fresh chicken is the dominant source of human infection. The seriousness of this epidemic justifies rapid, decisive action to reduce human exposure to this pathogen. There is good international evidence to support removal of fresh chicken from the food supply, with its reintroduction only when it can be shown to pose a very low risk to human health. Because freezing can substantially reduce Campylobacter levels, frozen chicken could be substituted to allow continued consumption of this popular food. Efforts to reduce Campylobacter colonisation of poultry flocks and contamination during chicken processing and distribution, along with continued consumer education, are important, but do not appear sufficient to control this epidemic in the short to medium term.