Identification of Atoxigenic Aspergillus flavus Isolates to Reduce Aflatoxin Contamination of Maize in Kenya.

Aspergillus flavus has two morphotypes, the S strain and the L strain, that differ in aflatoxin-producing ability and other characteristics. Fungal communities on maize dominated by the S strain of A. flavus have repeatedly been associated with acute aflatoxin poisonings in Kenya, where management tools to reduce aflatoxin levels in maize are needed urgently. A. flavus isolates (n = 290) originating from maize produced in Kenya and belonging to the L strain morphotype were tested for aflatoxin-producing potential. A total of 96 atoxigenic isolates was identified from four provinces sampled. The 96 atoxigenic isolates were placed into 53 vegetative compatibility groups (VCGs) through complementation of nitrate non-utilizing mutants. Isolates from each of 11 VCGs were obtained from more than one maize sample, isolates from 10 of the VCGs were detected in multiple districts, and isolates of four VCGs were found in multiple provinces. Atoxigenic isolates were tested for potential to reduce aflatoxin concentrations in viable maize kernels that were co-inoculated with highly toxigenic S strain isolates. The 12 most effective isolates reduced aflatoxin levels by >80%. Reductions in aflatoxin levels caused by the most effective Kenyan isolates were comparable with those achieved with a United States isolate (NRRL-21882) used commercially for aflatoxin management. This study identified atoxigenic isolates of A. flavus with potential value for biological control within highly toxic Aspergillus communities associated with maize production in Kenya. These atoxigenic isolates have potential value in mitigating aflatoxin outbreaks in Kenya, and should be evaluated under field conditions.

High-resolution analysis of tomato leaf elongation: the application of novel time-series analysis techniques.

This paper demonstrates the use of a novel suite of data-based, recursive modelling techniques for the investigation of biological and other time-series data, including high resolution leaf elongation. The Data-Based Mechanistic (DBM) modelling methodology rejects the common practice of empirical curve fitting for a more objective approach where the model structure is not assumed a priori, but instead is identified directly from the data series in a stochastic form. Further, this novel approach takes advantage of the latest techniques in optimal recursive estimation of non-stationary and non-linear time-series. Here, the utility and ease of use of these techniques is demonstrated in the examination of two time-series of leaf elongation in an expanding leaf of tomato (Lycopersicon esculentum L. cv. Ailsa Craig) growing in a root pressure vessel (RPV). Using this analysis, the component signals of the elongation series are extracted and considered in relation to physiological processes. It is hoped that this paper will encourage the wider use of these new techniques, as well as the associated Data-Based Mechanistic (DBM) modelling strategy, in analytical plant physiology.

Critical incidents in the intensive therapy unit.

Preventable mishaps in an intensive therapy unit were studied over 12 months by the critical incident technique. Staff were encouraged to complete confidential questionnaires describing incidents in which they had participated or had observed. This allowed classification of the events and examination of the views of staff on causes, detection, and prevention. 110 (80%) of 137 events were felt to have been due to human error; the remainder were due to equipment failure. Inexperience with equipment and shortage of trained staff were the factors most often felt to contribute to incidents. The critical incident technique is a useful way of improving standards of clinical care.

Nosocomial respiratory tract colonization and infection with aminoglycoside-resistant Acinetobacter calcoaceticus var anitratus: epidemiologic characteristics and clinical significance.

During the period July 1983 through December 1984, aminoglycoside-resistant Acinetobacter calcoaceticus var anitratus (ACA) were isolated from 98 patients in a university hospital. Eighty-seven percent of patients (85/98) acquired aminoglycoside-resistant ACA in the intensive care unit (ICU) and 92% (90/98) of all initial isolates were from sputum. ICU patients with respiratory colonization/infection with aminoglycoside-resistant ACA were compared with matched ICU controls with other gram-negative rods in sputum. Compared with controls, the duration of ICU stay prior to colonization/infection with aminoglycoside-resistant ACA was significantly longer for cases (14.7 days v 5.9 days, P = 0.002). Although exposures to devices and procedures were not significantly different for the two groups, cases received respiratory therapy significantly longer than did controls (14.7 days v 6.6 days, P = 0.006). Prior to isolation of aminoglycoside-resistant ACA in sputum, cases received more cephalosporins than did controls (1.9 v 1.2, P = 0.018); aminoglycoside usage in the two groups was comparable but cases tended to have received aminoglycoside for longer durations before colonization/infection than had controls (9.0 days v 6.1 days, P = 0.08). Following sputum isolation of ACA, 6 of 22 cases developed ACA bacteremia compared with bacteremia in 2 of 22 controls. We conclude that factors predisposing to colonization/infection with aminoglycoside-resistant ACA were extended ICU care, prolonged respiratory therapy, and prior therapy with cephalosporins and aminoglycoside. In addition, ACA may be a more common cause of secondary bacteremia than previously appreciated.

Tuberculosis screening in the long-term care setting.

Tuberculosis (TB) skin-testing practices in long-term care facilities (LTCFs) in North Carolina (NC) were assessed from a 56% (148/263) response to a comprehensive TB screening questionnaire. TB skin tests were administered to employees on initial employment by 98% and annually by 97% of the LTCFs, generally (74%) by the Mantoux method. Employee skin tests were read at the appropriate time interval of 48 to 72 hours by 91%, but less than half used diameter of induration when interpreting reactive tests. The booster test was performed on new employees at eight (6%) of the LTCFs. TB skin tests were routinely performed on newly admitted residents by 56% or conditionally required by 18%, generally (73%) by the Mantoux method. Resident skin tests were read at the appropriate time interval of 48 to 72 hours by 92%, but again only half correctly interpreted reactive tests as significant. Residents received routine annual skin tests at 71% of the LTCFs, generally (80%) by the Mantoux method. Eight (6%) facilities routinely performed the booster test on newly admitted residents. TB infection prevalence in new employees during 1983 was 8.1% (47/578) in seven LTCFs and in newly admitted residents was 6.4% (7/110) in three LTCFs supplying this data. The five-year mean TB skin test conversion rate among employees was 1.1% (101/9545) in 12 LTCFs and among residents was 0.9% (46/5216) in nine LTCFs supplying this data. Lack of compliance to established TB skin-testing guidelines in NC LTCF was prevalent. In recognition of described endemic and epidemic spread of TB in LTCFs, residents and employees of LTCFs should be screened for TB utilizing established skin-testing practices.

Tuberculosis in hospital personnel.

Tuberculosis (TB) skin testing practices and the prevalence and inherent risk of TB infection among hospital employees in 167 North Carolina (NC) hospitals were determined from a 79% (132/167) response to a tuberculosis screening questionnaire. Preemployment TB skin testing was performed by 98% of responding hospitals, primarily (87%) by the Mantoux method. TB skin test reactions of greater than or equal to 10 mm were interpreted as significant by 72% and at the appropriate time interval of 48 to 72 hours after administration by 80%. The booster test was routinely performed in 12% of the hospitals. TB infection prevalence among new employees during 1983 was 6.3% (260/4137) in 30 hospitals supplying these data. A positive correlation was noted between employee infection prevalence and county TB case rates (P = .014). Skin test conversion data from 56 hospitals across the state revealed a five year mean conversion rate of 1.14% among 71,253 personnel. There was an association between the incidence of TB in the general population and the frequency of conversions among hospital employees in corresponding geographical regions. Similarly, the incidence of TB among approximately 100,000 NC hospital employees in 1983 and 1984 was less than the incidence in the general population. These associations suggest that the incidence of TB infection among hospital personnel may reflect the prevalence of tuberculosis in the community rather than an occupational hazard. Annual TB skin testing of hospital employees may be justified in eastern North Carolina where the incidence of tuberculosis (22-30 cases/100,000) is greater than the national average and where the risk of new TB infection among hospital employees is relatively common (greater than or equal to 1.5%).

Infection control programs in twelve North Carolina extended care facilities.

To assess the scope of infection control programs in extended care facilities, 1-day surveys were conducted in 12 North Carolina facilities over an 8-month period using a standardized questionnaire. All 12 facilities had a designated infection control practitioner (ICP), although none had attended an infection control education course. Eleven had an Infection Control Committee of which 8 (73%) met regularly. The Director of Nurses generally (58%) was the ICP and spent about 2 hr/wk on infection control. Ten (83%) facilities conducted infection surveillance among residents but did not accurately compute nosocomial infection rates. Eleven (92%) facilities had employee health programs that included preemployment and annual tuberculosis screening. None had a comprehensive resident health program. Infection control aspects of patient care practices often varied from facility to facility. Nosocomial infection surveillance among 336 residents in 9 facilities using modified CDC criteria revealed an overall prevalence rate of 5.4%. Additional infections were suspected but not included because of limitations of laboratory data and chart documentation.

A report on the consumption, composition and nutritional adequacy of a mixture of lush green perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata) fed ad libitum to Thoroughbred mares.

Non-pregnant Thoroughbred mares were stabled and subjected to 2 trials, each 24 h in duration, to establish their total consumption of a mixture of freshly cut, lush green perennial ryegrass (Lolium perenne) and cocksfoot (Dactylis glomerata) in approximately equal proportions; and to compare the total intake of crude protein, calcium, phosphorus and mass of the grass mixture on a dry matter basis with their daily nutritional requirements. The body mass of each mare was calculated at the commencement of each trial. In the first trial 2 lactating mares with foals at foot, 65 days and 8 days of age, and one mature non-lactating mare, consumed 75,5 kg, 61,0 kg and 39,5 kg of the grass mixture, cut in the early vegetative stage, respectively. The perennial ryegrasss (L. perenne) contained 79,63% moisture, 1,67% crude protein, 0,75% calcium, 0.057% phosphorus and 20.37% dry matter. The cocksfoot (D. glomerata) contained 79,52% moisture, 2,27% crude protein, 0,051% calcium, 0,061% phosphorus and 20,48% dry matter. The younger foal did not eat the grass mixture. The mass of grass mixture consumed by the older foal was not determined. In the second trial conducted 3 weeks later, when oat straw (Avena sativa) was also fed ad lib itum, the same lactating mares, but a different mature non-lactating mare, consumed 54.5 kg, 56.0 kg and 40.5 kg of the grass mixture, cut in the mid bloom stage, respectively. The perennial ryegrass (L. perenne) contained 70,03% moisture, 2,37% crude protein, 0,086% calcium 0,068% phosphorus and 29,97 dry matter.(ABSTRACT TRUNCATED AT 250 WORDS)