Cutinolytic esterase activity of bacteria isolated from mixed-plant compost and characterization of a cutinase gene from Pseudomonas pseudoalcaligenes.

The objective of the current study was to examine cutinolytic esterase (i.e., cutinase) activity by pseudomonads and bacteria isolated from mixed-plant compost. Approximately 400 isolates representing 52 taxa recovered from mixed-plant compost using cuticle baits, along with 117 pseudomonad isolates obtained from a culture collection (i.e., non-compost habitats), were evaluated. The ability of isolates to degrade the synthetic cutin polycaprolactone (PCL) was initially measured. Isolates from 23 taxa recovered from the compost degraded PCL. As well, isolates from 13 taxa of pseudomonads cleared PCL. Secondary screening measured esterase activity induced by the presence of apple cuticle using the chromogenic substrate p-nitrophenyl butyrate. Eighteen isolates representing four taxa (Alcaligenes faecalis , Bacillus licheniformis , Bacillus pumilus , and Pseudomonas pseudoalcaligenes) recovered from compost exhibited substantial esterase activity when grown with cuticle. In contrast, none of the pseudomonad isolates from the culture collection produced appreciable esterase activity. Although degradation of PCL was not correlated with esterase activity, isolates that were unable to degrade PCL failed to produce measureable esterase activities. Zymogram analysis indicated that the esterases produced by bacteria from compost ranged in size from 29 to 47 kDa. A gene from P. pseudoalcaligenes (cutA) was found to code for a cutin-induced esterase consisting of 302 amino acids and a theoretical protein size of 32 kDa. The enzyme was unique and was most closely related to other bacterial lipases (≤48% similarity).

Farm-to-fork characterization of Escherichia coli associated with feedlot cattle with a known history of antimicrobial use.

This study investigated antimicrobial-resistant (AR) Escherichia coli isolated from "farm-to-fork" production of cattle fed diets containing the antimicrobial growth promoter (AGP) chlortetracycline plus sulfamethazine (44ppm each, AS700) or no AGP (control). For each treatment, samples included: feces just prior to euthanization; hides after euthanization; intestinal digesta from the lower digestive tract; carcasses immediately after evisceration and after 24h in the chiller; and ground beef stored at 5 degrees C for 1 and 8days. Samples were also collected from the abattoir environment and from air during hide removal. Total, ampicillin (Amp(r))-, and tetracycline (Tet(r))-resistant E. coli were isolated on MacConkey agar or MacConkey agar containing ampicillin or tetracycline, respectively. Amp(r) and Tet(r)E. coli were isolated from the feces and hides of all cattle. Compared to the control, the prevalence of Amp(r) (26.5% vs. 7.9%) and Tet(r) (50.9% vs. 12.6%) E. coli was greater in feces from AS700 treated animals (P<0.05), but was similar between treatments for hide samples (P>0.05). The prevalence of carcass or ground beef contamination with AR E. coli was not different between treatments. Resistant E. coli were isolated from the abattoir environment after processing of both groups of cattle. Susceptibilities to 11 antimicrobials and pulsed-field gel electrophoresis (PFGE) analyses were conducted on 360 Amp(r) and Tet(r)E. coli isolates. Twenty-five antibiogram profiles were detected, with isolates exhibiting resistance to up to 9 antimicrobials. Most (28.2%) Amp(r)E. coli were also resistant to streptomycin and tetracycline, whereas Tet(r)E. coli (53.5%) were mainly resistant to only tetracycline. Thirty one genotypes were detected by PFGE with most isolates from meat and environmental samples having similar genetic profiles to isolates from hides or digesta. These data demonstrate that antimicrobial-resistant E. coli can contaminate meat products during slaughter and enter the food chain regardless of whether or not cattle are administered AGP. The abundance of AR E. coli on the hides of animals is likely a key element for controlling end-product contamination.

Prophylactic systemic antibiotics to reduce morbidity and mortality in neonates with central venous catheters.

BACKGROUND: The use of central venous catheters is recognised as a risk factor for nosocomial infection. Prophylactic antibiotics may be effective in preventing catheter-related blood stream infection in newborns but may also have the undesirable effect of promoting the emergence of resistant strains of micro-organisms. OBJECTIVES: To determine the effect of prophylactic antibiotics on mortality and morbidity in neonates with central venous catheters. SEARCH STRATEGY: Searches were done of the Cochrane Neonatal Review Group Specialised Register, MEDLINE from 1950 to April 2007, CINAHL from 1982 to April 2007, and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2 2007). Previous reviews (including cross references) were also searched. SELECTION CRITERIA: Randomised controlled trials or quasi-randomised controlled trials of adequate quality in which either individual newborn infants or clusters of infants were randomised to receive prophylactic antibiotics (not including antifungals) versus placebo or no treatment. Infants must have had central venous catheters, been full term infants less than 28 days old or preterm infants up to 44 weeks (postmenstrual) corrected age. DATA COLLECTION AND ANALYSIS: Criteria and methods used to assess the methodological quality of the trials: standard methods of the Cochrane Collaboration and its Neonatal Review Group were used. The review authors extracted data independently. Attempts were made to contact study investigators for additional information as required. MAIN RESULTS: Three small studies have been included in this review. Prophylactic antibiotics in neonates with central venous catheters had no effect on overall mortality (typical RR 0.68, 95% confidence interval 0.31, 1.51). Prophylactic antibiotics in neonates with central venous catheters decreased the rate of proven bacterial sepsis (typical RR 0.38, 95% confidence interval 0.18, 0.82). Prophylactic antibiotics in neonates with central venous catheters decreased the rate of suspected or proven bacterial septicaemia (typical RR 0.40, 95% confidence interval 0.20, 0.78). No resistant organisms colonising infants were identified in any of the studies. No pooled data were available for other important outcome measures such as chronic lung disease or neurodevelopmental outcome. AUTHORS' CONCLUSIONS: Prophylactic systemic antibiotics in neonates with a central venous catheter reduces the rate of proven or suspected septicaemia. However, this may not be clinically important in the face of no significant difference in overall mortality and the lack of data on long-term neurodevelopmental outcome. Furthermore, there is a lack of data pertaining to the potentially significant disadvantages of this approach such as the selection of resistant organisms. The routine use of prophylactic antibiotics in infants with central venous catheters in neonatal units cannot currently be recommended.

Molecular detection of bovine and porcine Torque teno virus in plasma and feces.

Torque teno virus (TTV) is frequently detected in humans, livestock and some companion animals. Very little is known about presence of TTV in Canadian livestock and the goal of this study was to evaluate the presence of TTV in swine and cattle using molecular tools. TTV DNA was detected and confirmed by sequencing in the plasma of 90.5% and in the feces of 60.3% of the animals tested in a single swine herd as well as 80.9% and 1.1% in the plasma of individuals from general Quebec swine and cattle populations, respectively. The impact of the TTV presence in livestock population for the agri-food chain should be further investigated.

Prophylactic antibiotics to reduce morbidity and mortality in neonates with umbilical artery catheters.

BACKGROUND: Umbilical artery catheters are often used in unwell neonates. Infection related to the use of these catheters may cause significant morbidity and mortality. The use of prophylactic antibiotics has been advocated for all newborns with umbilical artery catheters in order to reduce the risk of colonisation and acquired infection. Countering this is the possibility that harm, such as the emergence of antibiotic resistant organisms, may outweigh benefit. OBJECTIVES: The primary objective was to assess whether prophylactic antibiotics reduce mortality and morbidity in neonates with umbilical artery catheters. Two different policies regarding the prophylactic use of antibiotics in neonates with umbilical artery catheters were reviewed: 1) a policy of prophylactic antibiotics for the duration of catheterisation (or other fixed duration of antibiotic treatment) versus placebo or no treatment among neonates with umbilical artery catheters; 2) a policy of continuing versus discontinuing prophylactic antibiotics among neonates with umbilical artery catheters who had been started on antibiotics at the time of catheterisation but whose initial cultures to rule out sepsis are negative. SEARCH STRATEGY: MEDLINE (January 1950 to May 2007), CINAHL (1982 to May 2007), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007), the Cochrane Neonatal Group Specialised Register and reference lists of articles were searched. SELECTION CRITERIA: Randomised and some non-randomised (i.e., quasi-randomised trials) controlled trials of adequate quality in which newborn infants with umbilical artery catheters are randomised to receive prophylactic antibiotics versus placebo or no treatment. DATA COLLECTION AND ANALYSIS: Two reviewer authors independently assessed trial quality. MAIN RESULTS: Two quasi-randomised trials have been included. However, given their poor quality, we have not pooled the results. There were no statistically significant differences in important outcomes in either study. AUTHORS' CONCLUSIONS: There is insufficient evidence from randomised trials to support or refute the use of prophylactic antibiotics when umbilical artery catheters are inserted in newborn infants, and no evidence to support or refute continuing antibiotics once initial cultures rule out infection in newborn infants with umbilical artery catheters.

Prophylactic antibiotics to reduce morbidity and mortality in ventilated newborn infants.

BACKGROUND: Intubation is associated with bacterial colonisation of the respiratory tract and, therefore, may increase the risk of acquiring an infection. The infection may prolong the need for mechanical ventilation and increase the risk of chronic lung disease. The use of prophylactic antibiotics has been advocated for all mechanically ventilated newborns in order to reduce the risk of colonisation and the acquisition of infection. However, there is the possibility that the harm this may cause might outweigh the benefit. OBJECTIVES: To assess the effects of prophylactic antibiotics on mortality and morbidity in intubated, ventilated newborn infants who are not known to have infection. In separate comparisons, two different policies regarding the prophylactic use of antibiotics in intubated, ventilated infants were reviewed: 1) among infants who have been intubated for mechanical ventilation, a policy of prophylactic antibiotics for the duration of intubation versus placebo or no treatment 2) among intubated, ventilated infants who have been started on antibiotics at the time of intubation but whose initial cultures to rule out sepsis were negative, a policy of continuing versus discontinuing prophylactic antibiotics. SEARCH STRATEGY: MEDLINE (January 1950 to March 2007), CINAHL (1982 to March 2007), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2007), the Cochrane Neonatal Group Specialised Register and reference lists of articles were searched. SELECTION CRITERIA: Randomised controlled trials of sufficient quality in which mechanically ventilated newborn infants are randomised to receive prophylactic antibiotics versus placebo or no treatment. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality. MAIN RESULTS: Two studies met the criteria for inclusion in this review. One was of insufficient quality to draw any meaningful conclusions. The other was of fair quality and found no significant differences between treatment and control groups in any of the reported outcomes, however, the rates of septicaemia were not reported. AUTHORS' CONCLUSIONS: There is insufficient evidence from randomised trials to support or refute the use of prophylactic antibiotics when starting mechanical ventilation in newborn infants, or to support or refute continuing antibiotics once initial cultures have ruled out infection in mechanically ventilated newborn infants.

Temporal prevalence of antimicrobial resistance in Campylobacter spp. from beef cattle in Alberta feedlots.

Antimicrobial resistance (AMR) was temporally assessed in campylobacters isolated from beef cattle (7,738 fecal samples from 2,622 animals) in four commercial feedlots in Alberta. All calves were administered chlortetracycline and oxytetracycline in feed, and a majority of the animals (93%) were injected with long-acting oxytetracycline upon arrival at the feedlot. Fecal samples from individual animals were collected upon arrival (i.e., entry sample), 69 days (standard deviation [SD] = 3 days) after arrival (i.e., interim sample), and 189 days (SD = 33 days) after arrival (i.e., exit sample) at the feedlot. In total, 1,586 Campylobacter isolates consisting of Campylobacter coli (n = 154), Campylobacter fetus (n = 994), Campylobacter jejuni (n = 431), Campylobacter hyointestinalis (n = 4), and Campylobacter lanienae (n = 3) were recovered and characterized. The administration of antimicrobials did not decrease carriage rates of campylobacters, and minimal resistance (< or =4%) to azithromycin, ciprofloxacin, enrofloxacin, gentamicin, and meropenem was observed. In contrast, substantive increases in the prevalence of isolates resistant to tetracycline and doxycycline (56 to 89%) for C. coli, C. fetus, and C. jejuni, as well as in the number of animals (7 to 42%) from which resistant isolates were recovered, were observed during the feedlot period. Increased resistance to erythromycin (total isolates and carriages rates) was also observed in isolates of C. coli over the three isolation times. The majority of C. fetus isolates recovered were resistant to nalidixic acid, but this was independent of when they were isolated. A relatively limited number of multidrug-resistant isolates were recovered and consisted primarily of C. coli resistant to tetracyclines and erythromycin (10% of isolates). Over the course of the feedlot period, considerable increases in antimicrobial resistance were observed in C. coli, C. fetus, and C. jejuni, but with the exception of erythromycin resistance in C. coli, the administration of antimicrobial agents to beef cattle was found to have a minimal impact on resistance to macrolides and fluoroquinolones, the two classes of antimicrobials used to treat campylobacteriosis in humans. However, the widespread use of antimicrobial agents in beef production and the possible horizontal transfer of mobile genetic elements with antimicrobial resistance determinants among Campylobacter and other bacterial taxa emphasize the need to monitor AMR development in bacteria from beef cattle.

Prophylactic antibiotics to reduce morbidity and mortality in neonates with umbilical venous catheters.

BACKGROUND: Umbilical venous catheters are often used in unwell neonates. Infection related to the use of these catheters may cause significant morbidity and mortality. The use of prophylactic antibiotics has been advocated for newborns with umbilical venous catheters in order to reduce the risk of colonisation and acquired infection. Countering this is the possibility that harm may outweigh benefit. Prophylactic antibiotics may be effective in preventing catheter-related blood stream infection, but may have the undesirable effect of promoting the emergence of resistant strains of micro-organisms. A policy of prophylactic antibiotic use should take into account this possibility, and has been used as a basis for arguing against its implementation. OBJECTIVES: The primary objective was to assess whether prophylactic antibiotics, in neonates with umbilical venous catheters, reduce mortality and morbidity. In separate comparisons, we planned to review two different policies regarding the prophylactic use of antibiotics in neonates with umbilical venous catheters: 1) Among neonates with umbilical venous catheters, a policy of prophylactic antibiotics for the duration of catheterisation (or other fixed duration of antibiotic treatment) versus placebo or no treatment; 2) Among neonates with umbilical venous catheters who had been started on antibiotics at the time of catheterisation, but whose initial cultures to rule out sepsis are negative, a policy of continuing versus discontinuing prophylactic antibiotics. SEARCH STRATEGY: We searched MEDLINE (January 1966 to April 2005), CINAHL (1982 to April 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2005). SELECTION CRITERIA: Randomised controlled trials or quasi-randomised trials in which newborn infants with umbilical venous catheters are randomised to receive prophylactic antibiotics versus placebo or no treatment. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality. MAIN RESULTS: One study, of poor quality, met the criteria for inclusion in this review. Twenty-nine term infants, who had umbilical venous catheters inserted specifically for transfusion procedures for hyperbilirubinaemia or polycythaemia, allocated non-randomly (quasi-randomised - alternate allocation) to treatment (n = 15) or control (n = 14) groups. Those in the treatment group received penicillin and gentamicin for three days. 5/15 infants given antibiotics and 5/14 control infants having positive blood cultures three days after catheter insertion. All positive blood cultures were considered contaminated, due to lack of corroborating clinical and haematological evidence of infection. Therefore, no infants were identified with evidence of septicaemia. AUTHORS' CONCLUSIONS: There is insufficient evidence from randomised trials to support or refute the use of prophylactic antibiotics when umbilical venous catheters are inserted in newborn infants. There is no evidence to support or refute continuing antibiotics once initial cultures rule out infection in newborn infants with umbilical venous catheters.

Effects of subtherapeutic administration of antimicrobial agents to beef cattle on the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter hyointestinalis.

The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (> or =94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a forage-based diet as opposed to a grain-based diet. The findings of this study show that the subtherapeutic administration of tetracycline, alone and in combination with sulfamethazine, to feedlot cattle can select for the carriage of resistant strains of Campylobacter species. Considering the widespread use of in-feed antimicrobial agents and the high frequency of beef cattle that shed campylobacters, the development of AMR should be monitored as part of an on-going surveillance program.

Prophylactic antibiotics to reduce morbidity and mortality in neonates with umbilical artery catheters.

BACKGROUND: Umbilical artery catheters are often used in unwell neonates. Infection related to the use of these catheters may cause significant morbidity and mortality. The use of prophylactic antibiotics has been advocated for all newborns with umbilical artery catheters in order to reduce the risk of colonisation and acquired infection. Countering this is the possibility that harm may outweigh benefit. OBJECTIVES: The primary objective was to assess whether prophylactic antibiotics, in neonates with umbilical artery catheters, reduce mortality and morbidity. In separate comparisons, we planned to review two different policies regarding the prophylactic use of antibiotics in neonates with umbilical artery catheters: 1) among neonates with umbilical artery catheters, a policy of prophylactic antibiotics for the duration of catheterisation (or other fixed duration of antibiotic treatment) versus placebo or no treatment; 2) among neonates with umbilical artery catheters who had been started on antibiotics at the time of catheterisation but whose initial cultures to rule out sepsis are negative, a policy of continuing versus discontinuing prophylactic antibiotics. SEARCH STRATEGY: We searched MEDLINE (January 1966 to February 2004), CINAHL (1982 to February 2004), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2004), the Cochrane Neonatal Group Specialised Register and reference lists of articles. SELECTION CRITERIA: Randomised controlled trials of adequate quality in which newborn infants with umbilical artery catheters are randomised to receive prophylactic antibiotics versus placebo or no treatment. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality. MAIN RESULTS: No study met the criteria for inclusion in this review. REVIEWERS' CONCLUSIONS: There is no evidence from randomised trials to support or refute the use of prophylactic antibiotics when umbilical artery catheters are inserted in newborn infants, or to support or refute continuing antibiotics once initial cultures rule out infection in newborn infants with umbilical artery catheters.

Chronic shedding of Campylobacter species in beef cattle.

AIMS: To determine the prevalence of chronic shedding of Campylobacter species by beef cattle, a longitudinal study of shedding patterns was conducted in a cohort of 60 beef steers over a 4-month period. METHODS AND RESULTS: Steers were maintained in a simulated feedlot setting but individually in pens to minimize transmission among animals. At each collection time, campylobacters in faeces were detected using conventional PCR. In addition, quantities of Campylobacter jejuni and C. lanienae in faeces were measured using real-time quantitative (RTQ) PCR. All of the steers tested shed Campylobacter species during the course of the study, and overall, 90% of the 299 samples tested were positive for Campylobacter DNA. The majority of the animals (86%) shed campylobacters at >/=4 sample times. The most prevalent taxon detected in bovine faeces was C. lanienae (56% of samples) followed by C. jejuni (13%), C. hyointestinalis (8%), and C. fetus (2%). No C. coli was detected, and 13% of the faecal samples contained two or more of the above species. Seven (12%) and 34 (57%) animals shed C. jejuni and C. lanienae at >/=3 sample times, respectively. For both C. lanienae and C. jejuni, a substantial number of cells were detected in faeces using RTQ-PCR; 27% of the samples positive for C. jejuni contained populations >10(4) cells g(-1) (maximum of 5 x 10(5) cells g(-1)), and 44% of samples positive for C. lanienae possessed populations >10(6) cells g(-1) (maximum of 4 x 10(8) cells g(-1)). A significant correlation was observed between shedding of C. lanienae and the severity of liver abscesses. In 27% of the samples, an amplicon was obtained for genus-specific but not for the species-specific primers. Sequencing of the partial 16S rRNA gene suggested the presence of at least two undescribed Campylobacter species but this has yet to be confirmed. CONCLUSIONS: A high percentage of feedlot cattle shed large quantities of Campylobacter species in their faeces over a protracted period of time (ca 112 days). SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study of longitudinal shedding patterns of campylobacters in beef cattle using PCR-detection methods. In addition, this is the first use of RTQ-PCR to directly quantify C. jejuni or C. lanienae in faeces. The results of the study show that a large number of cattle (>85%) chronically shed campylobacters in feedlots.

Influence of antimicrobial agents on the spoilage of a meat-based entomophage diet.

The microbial decomposition of a meat-based entomophage diet presented in Parafilm packets was investigated. Considerable bacteria but not fungi were associated with components used to prepare the diet (i.e., hens' eggs, liver, and ground beef). At the initial sampling time, there were no differences among diet treatments in the size of bacterial or fungal populations. Bacterial populations in diets not containing antibacterial agents rapidly increased and reached an asymptote by 24 h (approximately 10(10) colony-forming units per gram). Bacterial populations also increased in diets containing antibacterial agents, but they were significantly smaller than in diets not containing antibacterial agents. The most prevalent bacteria isolated were Carnobacterium piscicola, Carnobacterium divergens, Lactobacillus curvatus, Lactobacillus sakei, Leuconostoc mesenteroides, and Enterococcus spp., regardless of the antibacterial treatment used. The proliferation of fungi was delayed relative to bacteria, but significant differences were observed among the diet treatments. Fungi were most inhibited by sorbic acid and propionic acid in the absence of antibacterial agents. The most common fungi isolated were the yeasts Candida zeylanoides, Torulaspora globosa, and Yarrowia lipolytica. The pH of diets not containing antibacterial agents decreased rapidly and was highly correlated with increases in bacteria but not fungi. The results of this study demonstrate that antimicrobial agents significantly inhibit spoilage microorganisms in a meat-based diet and that alternative management strategies to delay the decomposition of such diets presented in Parafilm packets should target lactic acid spoilage bacteria, particularly Carnobacterium and Lactobacillus species.

Prophylactic antibiotics to reduce morbidity and mortality in ventilated newborn infants.

BACKGROUND: Bacterial colonisation of the respiratory tract is associated with intubation and may increase the risk of acquiring infection. This may prolong the need for mechanical ventilation and increase the risk of chronic lung disease. The use of prophylactic antibiotics has been advocated for all mechanically ventilated newborns in order to reduce the risk of colonisation and acquired infection. Countering this is the possibility that harm may outweigh benefit. OBJECTIVES: To assess the effects of prophylactic antibiotics in reducing mortality and morbidity in intubated and ventilated newborn infants who are not known to have infection. In separate comparisons, we reviewed two different policies regarding the prophylactic use of antibiotics in intubated, ventilated infants: 1) among babies who are being intubated for mechanical ventilation, a policy of prophylactic antibiotics for the duration of intubation versus placebo or no treatment. 2) among intubated, ventilated babies who had been started on antibiotics at the time of intubation but whose initial cultures to rule our sepsis are negative, a policy of continuing versus discontinuing prophylactic antibiotics. SEARCH STRATEGY: We searched MEDLINE (January 1966 to May 2003), CINAHL (1982 to May 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2003), the Cochrane Neonatal Group Specialised Register and reference lists of articles. SELECTION CRITERIA: Randomised controlled trials of sufficient quality in which mechanically ventilated newborn infants are randomised to receive prophylactic antibiotics versus placebo or no treatment. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality. MAIN RESULTS: One study, of insufficient quality, met the criteria for inclusion in this review. REVIEWER'S CONCLUSIONS: There is no evidence from randomised trials to support or refute the use of prophylactic antibiotics when commencing mechanical ventilation in newborn infants, or to support or refute continuing antibiotics once initial cultures rule out infection in mechanically ventilated newborn infants.

Impact of a novel species of Nosema on the southwestern corn borer (Lepidoptera: Crambidae).

A study was undertaken to elucidate the impact of an undescribed Nosema sp. on the southwestern corn borer (SWCB; Diatraea grandiosella Dyar). The Nosema sp. (isolate 506) included in the study was isolated from an overwintering SWCB larva in Mississippi. It was highly infectious per os, with a median infective dose of 2.0 x 10(3) spores per larva. Even at the highest dosage tested (10(7) spores per larva), minimal mortality (< or = 3%) was observed in infected larvae, pupae, and adults reared in the laboratory on an artificial diet. However, infected pupae (0- and 7-d-old) were smaller, and the time to adult eclosion from pupation was slightly increased. Furthermore, the number of eggs produced by infected SWCB female moths substantially decreased (32%), and this effect was most pronounced on day 2, when the greatest number of eggs were oviposited by infected and noninfected moths. For eggs produced by infected females mated with infected males, hatch was slightly decreased by 16 and 15% for eggs laid on days 2 and 3, respectively. In addition, egg hatch was reduced in eggs oviposited by noninfected females mated with infected males on day 3. A low prevalence of infection (< 6%) was observed in the F1 generation originating from infected females mating with noninfected males, from noninfected females mating with infected males, and from infected females mating with infected males. Nosema 506 spores were observed in the proximity of reproductive tissues of infected female and male moths. Spores also were detected on the chorion surface and within eggs laid by infected females. Furthermore, 1-11% of larvae hatching from surface-sterilized eggs were infected by Nosema 506 indicating a transovarial mechanism of transmission.

The use of meconia to nondestructively detect sublethal infections in heliothines (Lepidoptera: Noctuidae).

The utility of using meconia to nondestructively detect entomopathogens of lepidopterous heliothines was examined. Early-instar tobacco budworm [Heliothis virescens (F.)] or cotton bollworm [Helicoverpa zea (Boddie)] larvae were inoculated with cytoplasmic polyhedrosis virus (CPV), Serratia marcescens Bizio, or Nosema heliothidis Lutz and Splendor, and the presence of each of the entomopathogens in adults and the meconia discharged during adult eclosion was determined. As the dose of CPV occlusion bodies and N. heliothidis spores but not S. marcescens cells ingested by larvae increased, a greater number of both adults and meconia were infested with the entomopathogens. For all three entomopathogens, no difference was observed between males and females for any of the parameters tested. The accuracy of the meconium method for predicting the presence of the entomopathogens in the adults (i.e., number of individuals in which meconia and adults were both positive, or meconia and adults were both negative) was > or = 92% for CPV, and > or = 79% for S. marcescens and N. heliothidis. Very few false negative predictions (i.e., the meconium was negative but the adult was positive) were observed for CPV (< or = 1%). The prevalence of false negative predictions ranged from 2 to 9%, and 5 to 21% for S. marcescens and N. heliothidis, respectively. The prevalence of false positive predictions (i.e., the meconium was positive but the adult was negative) was < or = 7% for CPV, < or = 13% for S. marcescens, and 0% for N. heliothidis. The results of this study demonstrate that although not absolute, the meconium method will be an efficacious method to detect nondestructively entomopathogens causing sublethal infections in heliothines, and possibly other insects, and thereby facilitate the rearing of specific pathogen free insects.

A survey of Campylobacter species shed in faeces of beef cattle using polymerase chain reaction.

A polymerase chain reaction (PCR)-based survey of campylobacters associated with faeces collected from 382 beef cattle was undertaken. To ensure the removal of PCR inhibitors present in faeces and determine if adequate extraction was achieved, faeces were seeded with internal control DNA (i.e., DNA designed to amplify with the Campylobacter genus primer set, but provide a smaller amplicon) before the extraction procedure. In only two samples (0.5%) were the internal control or Campylobacter genus amplicons not detected. In the remaining 380 faecal samples, Campylobacter DNA was detected in 83% of the faecal samples (80% of the faecal samples were positive for Campylobacter genus DNA, and 3% of the samples were negative for Campylobacter genus DNA but positive for DNA of individual species). The most frequently detected species was Campylobacter lanienae (49%), a species only recently connected to livestock hosts. Campylobacter jejuni DNA was detected in 38% of the faecal samples, and Campylobacter hyointestinalis and Campylobacter coli DNA were detected in 8% and 0.5% of the samples, respectively. Campylobacter fetus DNA was not detected. Twenty-four percent of the faecal samples contained DNA of at least two species of Campylobacter. Of these samples, the majority (81%) contained DNA of C. jejuni and C. lanienae. The results of this study indicate that beef cattle commonly release a variety of Campylobacter species into the environment and may contribute to the high prevalence of campylobacteriosis in humans inhabiting areas of intensive cattle production, such as southern Alberta. Furthermore, this study demonstrates the utility of using PCR as a rapid and accurate method for simultaneously detecting the DNA of a diverse number of Campylobacter species associated with bovine faeces.

Phylogenetic relationships among strains of the entomopathogenic fungus, Nomuraea rileyi, as revealed by partial beta-tubulin sequences and inter-simple sequence repeat (ISSR) analysis.

AIMS: To elucidate the phyletic relationships among three members of the entomogenous fungal genus, Nomuraea, with an emphasis on N. rileyi. METHODS AND RESULTS: Relationships were evaluated by analysis of the beta-tubulin gene and of inter-simple sequence repeats (ISSR). The amplification product of the partial beta-tubulin gene was larger for N. atypicola than for N. rileyi, and sequencing of this gene fragment confirmed that N. atypicola possesses approximately 25 more nucleotides than N. rileyi and N. anemonoides. Based on neighbor joining and bootstrap analysis of the partial beta-tubulin gene, N. atypicola failed to form a monophyletic grouping with the other two species of Nomuraea. In contrast, the single isolate of N. anemonoides clustered with the N. rileyi isolates, and both taxa grouped with Epichloe typhina (Hypocreales: Clavicipitaceae). Results from this study suggested that N. rileyi and N. anemonoides are closely related to the Clavicipitaceae. In contrast, evidence indicated that N. atypicola is not closely related to this family, and that this taxon is not a Nomuraea. Based on the 83 polymorphic loci of ISSR, it was observed that isolates of N. rileyi from diverse geographical origins were distinctly different from both N. atypicola and N. anemonoides. Considerable heterogeneity was observed in the 18 isolates of N. rileyi tested, and several clusters contained isolates from disparate geographical locations and hosts. However, three isolates from the Philippines (three host species) and three strains isolated from velvetbean caterpillar (Anticarsia gemmatalis) larvae in South America did cluster together. Two other strains from Brazil (isolated from Spodoptera spp.) were distinct from the velvetbean caterpillar isolates from South America. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The beta-tubulin gene was generally too conserved to resolve intraspecies variability. However, ISSR did identify polymorphisms among the isolates of N. rileyi tested. The results of this study indicate that ISSR may be used as robust molecular markers for studying the population genetics of this entomopathogenic fungus.

Comparative degradation of oomycete, ascomycete, and basidiomycete cell walls by mycoparasitic and biocontrol fungi.

Fourteen fungi (primarily representing mycoparasitic and biocontrol fungi) were tested for their ability to grow on and degrade cell walls (CWs) of an oomycete (Pythium ultimum), ascomycete (Fusarium equisetii), and basidiomycete (Rhizoctonia solani), and their hydrolytic enzymes were characterized. Protein was detected in the cultural medium of eleven of the test isolates, and these fungi significantly degraded CWs over the 14-day duration of the experiment. In general, a greater level of CW degradation occurred for F. equisetii and P. ultimum than for R. solani. Fungi that degraded F. equisetii CWs were Coniothyrium minitans, Gliocladium roseum, Myrothecium verrucaria, Talaromyces flavus, and Trichoderma harzianum. Taxa degrading P ultimum CWs included Chaetomium globosum, Coniothyrium minitans, M. verrucaria, Seimatosporium sp., Talaromyces flavus, Trichoderma hamatum, Trichoderma harzianum, and Trichoderma viride. Production of extracellular protein was highly correlated with CW degradation. Considerable variation in the molecular weights of CW-degrading enzymes were detected among the test fungi and the CW substrates in zymogram electrophoresis. Multivariate analysis between CW degradation and hydrolysis of barley beta-glucan (beta1,3- and beta1,4-glucanases), laminarin (beta1,3- and beta1,6-glucanases), carboxymethyl cellulose (endo-beta1,4-glucanases), colloidal chitin (chitinases), and chitosan (chitosanases) was conducted. For F. equisetii CWs, the regression model accounted for 80% of the variability, and carboxymethyl cellulases acting together with beta-glucanases contributed an R2 of 0.52, whereas chitinases and beta-glucanases alone contributed an R2 of 0.11 and 0.12, respectively. Only 61% of the variability observed in the degradation of P. ultimum CWs was explained by the enzyme classes tested, and primarily beta-glucanases (R2 of 0.53) and carboxymethyl cellulases (R2 of 0.08) alone contributed to CW break down. Too few of the test fungi degraded R. solani CWs to perform multivariate analysis effectively. This study identified several fungi that degraded ascomyceteous and oomyceteous, and to a lesser extent, basidiomycetous CWs. An array of enzymes were implicated in CW degradation.

Effects of Serratia marcescens on the F1 generation of laboratory-reared Heliothis virescens (Lepidoptera: Noctuidae).

The effects of the bacterium Serratia marcescens (Bizio) was investigated on the F1 generation of laboratory-reared Heliothis virescens (F.). There was no difference in adult male or female longevity (i.e., parental generation) for individuals inoculated with S. marcescens as larvae (Serratia treatment) and those that were free of the bacterium (control treatment). However, the number of eggs laid and the prevalence of eclosion of eggs from Serratia treatment adults were reduced relative to control treatment adults. A very low number of F1 Serratia treatment eggs exhibited signs of infection, but a higher prevalence of mortality was observed for F1 larvae (n = 2,888) for the Serratia (3.5-4.6%) than for the control (1.1-1.5%) treatment. No S. marcescens was isolated from dead control larvae; whereas, 48 -54% of dead F1 larvae for the Serratia treatment were positive for the bacterium. However, there was no significant difference in larval weights between treatments. There were also no differences in either mortality or weight of F1 male pupae between treatments, but F1 female pupae were significantly smaller and prevalence of mortality was higher for the Serratia treatment. Serratia marcescens was not isolated from any of the control F1 pupae, but 6% of pupal cadavers for the Serratia treatment were positive for the bacterium. No S. marcescens was recovered from the meconia of any of the F1 adults (n = 2,600) regardless of treatment, and there were no differences in adult weights between treatments. Although sublethal effects of S. marcescens were detected, the impact and prevalence of the bacterium were tremendously reduced over the F1 generation in the absence of all but the most basic management strategies.

Production of cellulases and xylanases by low-temperature basidiomycetes.

Three of four isolates, representing phylogenetically distinct groupings of low-temperature basidiomycetes (LTB), were capable of utilizing wheat straw, and to a lesser extent conifer wood at 15 degrees C. A cottony snow mould LTB (LRS 013) and a fruit rot LTB (LRS 241) grown on straw significantly degraded filter paper, carboxymethylcellulose (CMC), p-nitrophenyl beta-glucopyranoside (i.e., beta-glucosidases), and xylan. Enzymes produced by Coprinus psychromorbidus (LRS 067) were limited to xylanases from straw and wood and beta-glucosidases from wood. A sclerotia-forming LTB (LRS 131) exhibited poor growth on both substrates, and did not produce detectable quantities of extracellular enzymes. None of the LTB isolates tested degraded avicel. The temperature optima of CMCases and xylanases in the filtrates from the straw medium ranged from 25 degrees C to 55 degrees C, and with the exception of LRS 067, significant activity was observed at 5 degrees C. Two cellulases (25 and 31 kDa) and two xylanases (24 and 34 kDa) were observed on zymograms for LRS 013 and 241. Reduction of enzymes with 2-mercaptoethanol adversely affected their activity on zymograms, and an additional cellulase band was observed for non-reduced samples. This study indicates that LTB produce an array of cellulolytic and xylanolytic enzymes, and that some of these enzymes possess low-temperature optima which may facilitate degradation of plant fibre under low-temperature conditions.