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Adherent-invasive Escherichia coli (AIEC) strains carry virulence genes (VGs) which are rarely found in strains other than E. coli. These strains are abundantly found in gut mucosa of patients with inflammatory bowel disease (IBD); however, it is not clear whether their prevalence in the gut is affected by the diet of the individual. Therefore, in this study, we compared the population structure of E. coli and the prevalence of AIEC as well as the composition of gut microbiota in fecal samples of healthy participants (n = 61) on either a vegan (n = 34) or omnivore (n = 27) diet to determine whether diet is associated with the presence of AIEC. From each participant, 28 colonies of E. coli were typed using Random Amplified Polymorphic DNA (RAPD)-PCR. A representative of each common type within an individual was tested for the presence of six AIEC-associated VGs. Whole genomic DNA of the gut microbiota was also analyzed for its diversity profiles, utilizing the V5-V6 region of the16S rRNA gene sequence. There were no significant differences in the abundance and diversity of E. coli between the two diet groups. The occurrence of AIEC-associated VGs was also similar among the two groups. However, the diversity of fecal microbiota in vegans was generally higher than omnivores, with Prevotella and Bacteroides dominant in both groups. Whilst 88 microbial taxa were present in both diet groups, 28 taxa were unique to vegans, compared to seven unique taxa in the omnivores. Our results indicate that a vegan diet may not affect the number and diversity of E. coli populations and AIEC prevalence compared to omnivores. The dominance of Prevotella and Bacteroides among omnivores might be accounted for the effect of diet in these groups.

We investigated the prevalence, persistence and virulence determinants of enterococci populations in water samples collected over three rounds following an extreme flood event in a metropolitan river. Enterococci (n = 482) were typed using the high resolution biochemical fingerprinting method (PhP typing) and grouped into common (C) or single (S) biochemical phenotypes (BPTs). In all, 23 C-BPTs (72.6% of isolates) were found across the sites. A representative isolate of each C-BPT was identified to the species level and tested for the presence of seven virulence genes (VGs), biofilm formation and resistance to 14 antibiotics. The enterococci concentrations in samples collected during the first two rounds were above national recreational water guidelines. By round three, enterococci concentrations decreased significantly (P < 0.05). However, 11 C-BPTs (55.5% of isolates) persisted across all sampling rounds. E. casseliflavus and E. mundtii were the most common enterococci populations comprising of >57% of all isolates. Ten of the 11 most dominant C-BPTs were resistant to multiple antibiotics and harboured one or more VGs. The high prevalence of antibiotic resistance and VGs among enterococci isolates in this catchment not only provides them with niche advantages but also poses a risk to public health.

Here we report a newly identified 'Chalky back' phenomenon in banana prawns (Fenneropenaeus merguiensis) farmed in North Queensland, Australia. This was characterized by localized white discoloured segmentation of the cervical groove, moreover, after cooking the prawns exploded, making them unfit for commercial sale. Histological examination revealed breakdown of gut and abdominal muscle tissue in some moribund specimens. We selectively isolated Vibrio spp., which are known prawn pathogens, from healthy and Chalky back specimens. Isolated bacteria were identified, typed and tested for the presence of eight virulence genes (VGs), biofilm formation, adherence and cytotoxicity to fish cells. In all, 32 isolates were recovered and identified as Vibrio harveyi, V. owensii, V. sinaloensis-like, V. campbellii, V. shilonii, Vibrio sp. and Photobacterium damselae using 16S rRNA gene sequencing. All V. harveyi carried VGs coding for haemolysin, toxR and flagella; formed biofilm; and adhered to both cell lines. This was similar to the V. sinaloensis-like strains that were only isolated from Chalky back specimens. Our data suggest that Vibrio spp. may play a role in the pathogenesis of Chalky back. This study is the first report of Chalky back phenomenon in farmed banana prawns that needs to be closely monitored by the industry.

Stingless bees accumulate deposits of plant resins that are mixed with beeswax to produce propolis. Previous studies have reported anti-microbial constituents of stingless bee (Tetragonula carbonaria) propolis from East Australia, but several components remained to be characterized. In the search of natural products yet unreported for Australian propolis, four bee deposit-resins of T. carbonaria bees were analysed by gas and liquid chromatography mass spectrometry with accurate mass measurements. Ethanolic extracts of the deposit-resins were tested in vitro against Staphylococcus aureus ATCC 25983 and Pseudomonas aeruginosa ATCC 27853 by the agar diffusion method. Phloroglucinols, flavonoids and isoprenoids were identified in samples. The crude extracts showed strong anti-staphylococcal effects but were less active against the Gram-negative bacterium. The diagnostic data enabled the identification of markers that can be used for profiling other Australian propolis sources and to target the isolation of bioactive phloroglucinols in future studies against antibiotic resistant S. aureus strains. Copyright © 2014 John Wiley & Sons, Ltd.

Vibrio and Pseudomonas species have been shown to be part of the normal microbiota of Atlantic salmon (Salmo salar L.), with some strains causing disease in fish. The factors affecting their prevalence and persistence in the salmon gut, however, have not been well studied. In this study, we collected 340 Vibrio and 150 Pseudomonas isolates from the hindgut of farmed Tasmanian Atlantic salmon, fed with two commercially available diets. Samples were collected every 6-8 weeks between July 2011 and May 2012. Isolates from selective agar were initially identified using biochemical tests and confirmed using genus-specific primers and 16S ribosomal RNA (16S rRNA) sequencing. Random amplified polymorphic DNA (RAPD) PCR was used to type both Pseudomonas and Vibrio; the latter was further typed using a biochemical fingerprinting method (PhP-RV plates). We observed low species diversity with strains comprising Vibrio ichthyoenteri/Vibrio scophthalmi, Vibrio crassostreae/Vibrio splendidus, Aliivibrio finisterrensis, Photobacterium phosphoreum and Pseudomonas fragi. Out of 340 Vibrio isolates, 238 (70 %) belonged to 21 clonal types and were found predominantly during summer when water temperatures reached 15 to 21 °C. Of these, the four major clonal types were found in multiple samples (70 %). P. fragi, on the other hand, was only found during the colder water temperatures and belonged to 18 clonal types. The presence of both groups of bacteria and their clonal types were independent of the fish diets used, suggesting that the water temperature was the main factor of the prevalence and persistence of these bacteria in the gut of Atlantic salmon.

Biodiverse environments provide a variety of resources that can be exploited by consumers. While many studies revealed a positive correlation between biodiversity and consumer biomass and richness, only few studies have investigated how resource diversity affects single consumers. To better understand whether a single consumer species benefits from diverse resources, we tested how the protective function of a defensive plant resource (i.e. resin exploited by social bees) varied among different sources and target organisms (predators, parasites and pathogens). To assess synergistic effects, resins from different plant genera were tested separately and in combination. We found that resin diversity is beneficial for bees, with its functional properties depending on the target organisms, type and composition of resin. Different resins showed different effects, and mixtures were more effective than some of the single resins (functional complementarity). We conclude that resins of different plant species target different organisms and act synergistically where combined. Bees that rely on resin for protection benefit more when they have access to diverse resin sources. Loss of biodiversity may in turn destabilize consumer populations due to restricted access to a variety of resources. © 2014, Springer-Verlag Berlin Heidelberg.

Propolis of Australian stingless bees (Tetragonula carbonaria, Meliponini) originating from Corymbia torelliana (Myrtaceae) fruit resins was tested for its antimicrobial activities as well as its flavonoid contents. This study aimed at the isolation, structural elucidation and antibacterial testing of flavanones of C. torelliana fruit resins that are incorporated into stingless bee propolis. Flavanones of this study were elucidated by spectroscopic and spectrometric methods including UV, 1D and 2D NMR, EI-MS, ESI-MS and HR-MS. The results indicated known C-methylated flavanones namely, 1 (2S)-cryptostrobin, its regioisomer 2 (2S)- stroboponin, 3 (2S)- cryptostrobin 7-methyl ether, and 6 (2S)- desmethoxymatteucinol, and known flavanones 4 (2S)- pinostrobin and 5 (2S)- pinocembrin as markers for C. torelliana fruit resins and one propolis type. Ethanolic preparations of propolis were shown to be active against Staphylococcus aureus (ATCC 25923) and to a lesser extent against Pseudomonas aeruginosa (ATCC 27853). C. torelliana flavanones inhibited the growth of S. aureus therefore contributing to the antibacterial effects observed for Australian stingless bee propolis extracts.

Farmed Tasmanian Atlantic salmon in Australia may experience water temperatures as high as 20°C during summer, which may impact on health and mariculture productivity. In this study we investigated the impact of two commercial feed on the major bacterial population in the gut of Atlantic salmon using an anaerobic semi-continuous fermenter model set at 20°C. Fermentation was conducted in a 5L culture vessel with 100 rpm agitation under CO2. For each diet the hindgut contents of three farmed Tasmanian Atlantic salmon were collected, mixed and used as fermenter inocula. Samples were collected at day 0, 1, 6 and 12 and used for bacterial enumeration and measurement of the functional status of the gut microbiota as well as their metabolic capacity (MC) values. With diet A, Vibrio spp. and lactic acid bacteria (LAB) increased over the course of fermentation. In contrast, diet B did not support the growth of LAB and instead promoted the growth of Plesiomonasshigelloides. MC values of gut microbiota receiving either diet also increased over the course of fermentation, reaching the highest level on day 12. This was independent of the type of diet used as the functional status of the microbiota for both diets was highly similar at each sampling round. Our results indicate that at the temperature experienced by Tasmanian Atlantic salmon during warm season i.e. 20°C, the type of diet may select for the growth of specific species of bacteria.

Biochemical fingerprinting (BF) databases of 524 enterococci and 571 Escherichia coli isolates and an antibiotic resistance analysis (ARA) database comprising of 380 E. coli isolates from four suspected sources (i.e. dogs, chickens, waterfowls, and human sewage) were developed to predict the sources of faecal pollution in a recreational coastal lake. Twenty water samples representing four sampling episodes were collected from five sites and the enterococci and E. coli population from each site were compared with those of the databases. The degree of similarity between bacterial populations was measured as population similarity (Sp) coefficient. Using the BF-database, bacterial populations of waterfowls showed the highest similarity with the water samples followed by a sewage treatment plant (STP). Higher population similarities were found between samples from STP and water samples especially at two sites (T2 and T3) which were located near the sewerage pipes collecting wastewater from the study area. When using the ARA-database, the highest similarity was found between E. coli populations from STP and water samples at sites T2 and T4. Both faecal indicators and as well as methods predicted human faecal pollution, possibly through leakage from submerged sewerage pipes. The results indicated that the Sp-analysis of faecal indicator bacterial populations from suspected sources and water samples can be used as a simple tool to predict the source(s) of faecal pollution in surface waters.

Aims: The aim of this study was to identify the prevalence of environmentally adapted enterococci strains by analysing biochemical fingerprinting (BF) data of 3952 enterococci isolates collected over 5 years from the six catchments in Southeast Queensland, Australia. Methods and Results: A BF method was used to type 3952 enterococci isolates from six catchments. The environmental isolates were compared with a large existing BF library comprised of 5803 enterococci isolates from 10 host groups. Environmental isolates belonged to 801 biochemical phenotypes (BPTs), of which, an average of 29.2% was specific to each catchment. When compared with the BF library, an average of 79·5% BPTs from each catchment was identical to those in the library (i.e. host-origin BPTs). The remaining 20·5% was regarded as non-host origin BPTs, as they were not in the library and constituted only 5·3% of the total isolates tested for each catchment. Conclusions: Our data suggest that less than 5% of studied environmental strains was not identical to those in the library and seemed to be of environmental origin. From a microbial source tracking context, such low level of environmentally adapted strains can have a minimal impact on the performance of the library-based methods if a large number of isolates were tested from both the host groups and environmental waters. Significance and Impact of the Study: These data shed light on the importance of the size and representativeness of library–based source-tracking methods and their implications for the identification of faecal pollution in environmental waters.

A collection of 366 Escherichia coli strains from 10 host groups and surface waters were tested for the presence of 15 virulence genes associated with strains causing intestinal and extra-intestinal infections. The virulence genes included eaeA, VT1, 2 and 2e, LT1, ST1 and 2, Einv gene, EAgg gene, CNF1 and 2, papC, O111 and O157 side chain LPS. Of the 262 strains obtained from nine different hosts, 39 (15%) carried one or more of these virulence genes. These included six strains from humans, two from horses, eight from dogs, two from ducks, five from cattle, seven from chickens, four from pigs, two from sheep and three from deer. Of the remaining 104 strains obtained from water samples, 10 (10%) also carried one or more of the tested virulence genes. Of these, six had identical biochemical phenotypes (BPTs) to strains isolated from humans (two strains), dogs (two strains), chickens (one strain) and sheep (one strain) with 4 BPTs also carrying same virulence genes. Our results indicate that the sources of clinically important E. coli strains found in surface waters due to faecal contamination can be predicted by using a combination of biochemical fingerprinting method and the detection of virulence genes. From the public health point of view this information will be of great importance for evaluating the risk associated with public use of the catchment.

A comparison of the efficacy of an existing large metabolic fingerprint database of enterococci and Escherichia coli with a locally developed database was undertaken to identify the sources of faecal contamination in a coastal lake, in southeast Qld., Australia. The local database comprised of 776 enterococci and 780 E. coli isolates from six host groups. In all, 189 enterococci and 245 E. coli biochemical phenotypes (BPTs) were found, of which 118 and 137 BPTs were unique (UQ) to host groups. The existing database comprised of 295 enterococci UQ-BPTs and 273 E. coli UQ-BPTs from 10 host groups. The representativeness and the stability of the existing database were assessed by comparing with isolates that were external to the database. In all, 197 enterococci BPTs and 179 E. coli BPTs were found in water samples. The existing database was able to identify 62.4% of enterococci BPTs and 64.8% of E. coli BPTs as human and animal sources. The results indicated that a representative database developed from a catchment can be used to predict the sources of faecal contamination in another catchment with similar landuse features within the same geographical area. However, the representativeness and the stability of the database should be evaluated prior to its application in such investigation

A biochemical fingerprinting method (the PhPlate system) was used to compare similarities between Escherichia coli and enterococci populations from surface water samples with those found in different animal species during the wet and the dry seasons in order to predict the dominant source(s) of fecal contamination in a local creek. A significant increase in the number and diversity of enterococci was observed in the creek during the wet season. Enterococci population from water samples also showed a higher population similarity with animal species than did E. coli. A higher population similarity was found between both indicator bacteria and animal species during the wet season with highest population similarities found in dogs, horses, cows and kangaroos. In contrast, a low population similarity was found for both fecal indicator bacteria from humans with water samples during the wet and the dry seasons, indicating that humans are not a major source of contamination in the studied creek. The results also indicate that the population similarity analysis of enterococci population has an advantage over E. coli in tracing the possible source(s) of contamination in the studied creek and that population similarity analysis as used in this study can be used to predict the source(s) of fecal contamination in surface waters.

AIMS: To provide evidence of septic system failure by comparing two faecal indicator bacteria, enterococci and Escherichia coli, from defective septic tanks and adjacent creeks. METHODS AND RESULTS: A biochemical fingerprinting method was used to type and compare enterococci and E. coli strains from 39 septic tanks with creek water samples. Phenotypic diversity of enterococci (0.5 +/- 0.3) and E. coli (0.5 +/- 0.3) in septic tanks were significantly lower than those found in water samples (0.8 +/- 0.1, P < 0.0001 for enterococci and 0.9 +/- 0.1, P < 0.0001 for E. coli). Among 1072 enterococci isolates tested from septic tanks, 203 biochemical phenotypes (BPTs) were found of which 98 BPTs from 33 septic tanks were identical to several water samples. Similarly, among 621 E. coli isolates tested from septic tanks, 159 BPTs were found of which 53 BPTs from 26 septic tanks were also identical to water samples. The number of the latter bacteria was significantly (P = 0.01) higher in water samples collected from downstream compared with that of upstream in the study area. A high similarity between the populations of both indicator bacteria was also found between defective septic tanks and downstream water samples further indicating the contamination of both creeks by defective septic systems. CONCLUSIONS: Biochemical fingerprinting of faecal indicator bacteria is a useful and rapid method to provide direct evidence for septic system failure. Combination of both faecal indicator bacteria (enterococci and E. coli) provides a better judgement of the performance of a septic system. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first to provide direct evidence of septic system failure by identifying the presence of specific bacterial types in septic tanks and surface waters. Based on our findings, we suggest that the performance evaluation of a septic system should be accompanied by direct analysis of faecal indicator bacteria.

A metabolic fingerprint database of enterococci and Escherichia coli from 10 host groups of animals was developed to trace the sources of fecal contamination in surface waters. In all, 526 biochemical phenotypes (BPTs) of enterococci and 530 E. coli BPTs were obtained from 4,057 enterococci and 3,728 E. coli isolates tested. Of these, 231 Enterococcus BPTs and 257 E. coli BPTs were found in multiple host groups. The remaining 295 Enterococcus BPTs and 273 E. coli BPTs were unique to individual host groups. The database was used to trace the sources of fecal contamination in a local creek. The mean diversities (Di) of enterococci (Di = 0.76 +/- 0.05) and E. coli (Di = 0.88 +/- 0.04) were high (maximum 1) in water samples, indicating diverse sources of fecal contamination. Overall, 71% of BPTs of enterococci and 67% of E. coli BPTs from water samples were identified as human and animal sources. Altogether, 248 Enterococcus BPTs and 282 E. coli BPTs were found in water samples. Among enterococci, 26 (10%) BPTs were identical to those of humans and 152 BPTs (61%) were identical to those of animals (animal BPTs). Among E. coli isolates, 36 (13%) BPTs were identical to those of humans and 151 (54%) BPTs were identical to those of animals. Of the animal BPTs, 101 (66%) Enterococcus BPTs and 93 (62%) E. coli BPTs were also unique to individual animal groups. On the basis of these unique Enterococcus BPTs, chickens contributed 14% of contamination, followed by humans (10%), dogs (7%), and horses (6%). For E. coli, humans contributed 13% of contamination, followed by ducks (9%), cattle (7%), and chickens (6%). The developed metabolic fingerprint database was able to distinguish between human and animal sources as well as among animal species in the studied catchment.

Faecal indicator microorganisms have long been used by water quality industries to assess the quality of surface, ground and shellfish-harvesting waters. However, none of these indicators are universally accepted as they lack of desired characteristics of a suitable indicator. Furthermore, they do not provide sufficient information regarding their source of origin. Over the past ten years, researchers have developed many phenotypic, genotypic and chemical methods to identify the faecal contamination in waterways by typing various indicator microorganisms. Ironically, there is no "gold standard" method for faecal source tracking. This paper is a critical evaluation of faecal indicators along with the advantages and limitations of current methods for tracking the sources of faecal contamination.

Coliforms are the members of the indigenous gut flora that most often translocate to mesenteric lymph nodes. Very few strains of Escherichia coli found in cecal contents of rats are able to translocate. The present study investigated the role of the composition of the gut flora for the occurrence of bacterial translocation. Two strains of E. coli (KI-C1 and KI-C2), previously shown to translocate in rats subjected to stress, were given by oral inoculation to rats lacking these strains. A biochemical fingerprinting method was used to identify bacteria in cecal contents, on cecal epithelium, and in mesenteric lymph nodes. In a challenge study, the inoculated E. coli strains were shown to colonize the rats and persist for up to 75 days in cecum. Subsequently, one group was starved for 24 h and a second group was subjected to experimental hemorrhage and then starved for 24 h before sampling for bacteriological analyses from blood, cecum, and mesenteric lymph nodes. Two parallel groups of rats served as controls and were not inoculated but otherwise received the same treatment before sampling. In the inoculated group, starved for 24 h, seven out of 11 rats showed translocation, whereas in the noninoculated group one of 11 rats showed translocation (P < 0.05). In groups subjected to hemorrhage and then starved for 24 h, 15/22 rats in the inoculated and 5/20 rats in the noninoculated group showed translocation (P < 0.01). These findings show that orally inoculated KI-C1 and KI-C2 strains can colonize the gut and can substantially increase bacterial translocation in rats subjected to mild and severe stress. The composition of the gut flora seems to be an underestimated factor in the pathophysiology of bacterial translocation.

Background: starvation for 24 h prior to experimental haemorrhage increases bacterial translocation in rats. Forty-eight hours starvation alone causes pronounced microbiological changes in caecal contents and a marked increase in bacterial adherence to caecal epithelium. The aim of the present study was to examine whether bulking fibre prevents these microbiological changes induced by starvation, i.e. mucosal adherence and/or bacterial translocationwith and without haemorrhage in rats. Methods: 32 rats were inoculated with the translocating Escherichia cell strain KI-C1. Groups of these rats were then starved for 48 h with or without access to bulking fibre. An additional group of rats was given bulking fibre and subjected to haemorrhage. A control group was untreated and given regular food. Samples were taken from caecal contents, caecal epithelium, mesenteric lymph nodes and blood. A biochemical fingerprinting method was used to characterize and compare E. coil strains in all samples. Results: ingestion of bulking fibre alone for 48 h significantly reduced the frequency of KI-C1 both in caecal contents and on caecal epithelium and completely prevented translocation of the strain, compared to starvation without bulking fibre for 48 h. Enforced stress (haemorrhage) increased bacterial translocation to the same level as starvation for 48 h. E. coli phenotypes found in mesenteric lymph nodes were also found adhering to the caecal epithelium. Conclusions: the presence of bulking fibre in gut lumen, by unknown mechanisms, reduces the frequency of an inoculated translocating strain of E. coil in caecal contents and on caecal epithelium and prevents its translocationto mesenteric lymph nodes.

Adult conventional rats were starved for 48 h with or without haemorrhage at 24 h, and translocation of caecal coliforms to mesenteric lymph nodes (MLNs) was measured. Translocation was detected in three of 11 rats without haemorrhage, in 6 of 11 starved and sham-operated rats and in 12 of 22 rats after haemorrhage. In contrast, only one of 13 non-instrumented and fed control rats showed translocation. Translocation was associated with more coliforms adhering to caecal epithelium in rats. Coliform isolates from caecum, caecal epithelium and MLNs were characterised and grouped into different biochemical phenotypes (BPTs) by a biochemical fingerprinting method. Of 291 BPTs detected in the caecum of all rats, 108 were also found on caecal epithelium; 36 BPTs were detected in MLNs, of which 17 were not detected either in the caecum or on the caecal epithelium of the corresponding rats. One isolate from each of these 36 BPTs was selected and compared to the others. Four common (C) BPTs (i.e., C1-C4) were identified among them. Strains of C1 formed the majority of isolates from the caecum (79%), caecal epithelium(71%) and MLNs (91%). In contrast, C2-C4 had a significantly lower incidence both in the caecum and on the caecal epithelium, but not in the MLNs. These findings indicate that not all caecal coliforms adhere to the epithelium during catabolic stress and that for translocation to occur, other bacterial properties besides adhesion are needed. It is also concluded that coliforms with a low incidence in the caecum can translocate with the same efficiency as those with a high incidence.

OBJECTIVE: To find out whether supplementation of an enteral diet with glutamine would reduce translocation of bacteria to mesenteric lymph nodes or blood after major haemorrhage in rats. DESIGN: Open randomised study. SETTING: University departments of surgery and microbiology, Sweden. MATERIAL: 49 Sprague-Dawley rats. INTERVENTIONS: Rats were fed enterally for 7 days on diets supplemented with either glutamine or an isonitrogenous amount of non-essential amino acids. After feeding, 8 experimental and 8 control rats underwent sham operation; 9 and 7, respectively, underwent moderate haemorrhage (to 65 mm Hg); and 9 and 8, respectively, underwent severe haemorrhage (50 mm Hg) without reinfusion. MAIN OUTCOME MEASURES: Microbiological analyses of samples of blood and mesenteric lymph nodes taken 24 hours after haemorrhage. RESULTS: The median (interquartile) number of colony forming units/mesenteric lymph nodes after moderate haemorrhage in animals who were given glutamine supplementation was 11 (0-34) and in control animals 20 (0-178). After severe haemorrhage the corresponding figures were 199 (10-310) and 22 (0-187). No pathogens were isolated from blood cultures. CONCLUSION: Glutamine supplementation before haemorrhage did not reduce bacterial translocation to mesenteric lymph nodes in this rat model.

OBJECTIVE: To investigate whether brief fasting before the induction of hypotension by non-lethal haemorrhage may induce translocation of enteric bacteria to mesenteric lymph nodes or blood in rats. DESIGN: Laboratory experiment. SETTING: University departments of surgery and microbiology, Sweden. MATERIAL: 39 Male Sprague-Dawley rats. INTERVENTIONS: 20 animals were fasted for 24 hours, all 39 then underwent controlled haemorrhage for 60 minutes that reduced the blood pressure to 55 mm Hg. MAIN OUTCOME MEASURES: Differences in blood loss, blood glucose concentrations, and packed cell volume; and aerobic cultures of mesenteric lymph nodes and blood. RESULTS: Fasted rats (n = 20) lost 2.3% of blood volume compared with 2.8% in fed rats(p < 0.001). Packed cell volume dropped by 11.3% in fasted rats and 16.5% in fed rats (p < 0.001). Glucose concentrations rose by 7.0 mmol/l in fasted rats compared with 21.0 mmol/l in fed rats (p < 0.001). Mesenteric lymph nodes contained enteric bacteria in 14/20 fasted rats compared with 6/19 fed rats (p < 0.05). In 4 fasted rats blood cultures grew pathogenic bacteria compared with no fed rats (p = 0.11). The number of bacteria found in mesenteric lymph nodes was significantly greater in fasted than in fed rats (p = 0.01). CONCLUSIONS: Brief fasting before hypotension caused by non-lethal haemorrhage was associated with significantly increased bacterial translocation compared with fed animals. Increases in blood glucose concentrations and plasma refill may have had a protective effect in fed rats. These experiments may be of clinical relevance as elective operations are usually preceded by overnight fasting.

Food deprivation 24 h before stress increases bacterial translocation in hemorrhage. Presently it tested whether hyperosmolality, induced by exogenous glucose infusion to improve plasma refill, prevents or reduces bacterial translocation after experimental hemorrhage in 24 h food-deprived rats. Rats were given an i.v. infusion of either 2 mL of 30% glucose (G) or the same volume of .9% NaCl (C) while simultaneously being submitted to a standardized 60 min hemorrhage period, of moderate or more severe hemorrhage. Blood was not reinfused. Despite development of marked hyperglycemia (p < .001, G vs. C) resulting in significantly greater reductions in packed cell volume (p < .001, G vs. C), bacterial translocation was detected similarly in both groups regardless of whether moderate (10/12-G, 9/12-C) or severe (15/19-G, 15/18-C) hemorrhage was inflicted. It was concluded that hyperglycemic hyperosmolality did not prevent bacterial translocation in these models of hemorrhagic stress in 24 h-starved rats.

Coliform bacteria are the most frequently reported bacteria to translocate afterhemorrhage. We investigated the correlation between composition and diversity of the cecal coliform flora and the degree of translocation in a rat model of hemorrhagic stress. Two groups of nine rats each were bled to 60 and 50 mm Hg mean arterial blood pressure, respectively. A sham-operated group without bleeding (n = 9) and a noninstrumented group (n = 6) served as controls. From each rat, 40 coliform isolates from the cecum and up to 16 from positive mesenteric lymph node (MLN) cultures were tested with an automated biochemical fingerprinting method. The phenotypic diversity of coliforms in each cecal sample was calculated as Simpson's diversity index (DI), and similarities between bacterial types in different samples were calculated as population similarity coefficients. Three rats in the sham-operated group and seven in each of the bled groups showed bacterial translocation. Of the different biochemical phenotypes (BPTs) found in the cecum of bled rats (mean, 6.5 BPTs), only a few were detected in MLNs (mean, 1.9 BPTs per MLN), with Escherichia coli being the dominant species. The translocating E. coli strains were mainly of two BPTs. Rats showing no translocation either did not carry these strains or had a high diversity of coliforms in the cecum. Furthermore, translocation of these coliform types was independent of their proportion in the cecum. In bled rats, the diversityof coliforms (mean DI, 0.53) was significantly higher than that in control groups (mean DI, 0.30; P = 0.004), suggesting that hemorrhage stimulates an increase in diversity of cecal coliforms. Rats with similar coliform flora and subjected to the same treatment showed similar patterns of translocation. Our results suggest that the composition of the coliformflora is an important factor in translocation and that certain coliform strains have the ability to translocate and survive in MLNs more easily than others.

Translocation of enteric bacteria has been suggested to compromise patients in severe catabolic stress. Mechanisms for this route of infection are not known. In this study, ratswere subjected to hemorrhage without reinfusion during 60 min, total blood loss was 3.28 +/- 0.14 ml/100 g BW. Control groups consisted of sham-operated animals without bleeding, and rats not operated at all. The mean number of viable bacteria found in mesenteric lymph nodes (MLN) of bled animals was 168 +/- 45 colony forming units (c.f.u./MLN), significantly higher compared to sham operated (5 +/- 3 c.f.u./MLN) and not operated (0 +/- 0 c.f.u./MLN) controls (P < 0.01). Cultures from MLN were positive in 7/9 rats after bleeding, in 3/9 of sham operated, and in 0/6 of non-instrumented control animals. No positive blood cultures were isolated. Escherichia coli was the dominant species found in MLN. A biochemical fingerprinting method (the PhP system) was used to identify translocating strains of E. coli among strains found in cecum. The method was also used to compare translocating strains between different animals. Our findings reveal that bacteria translocate to MLN after hemorrhage. Some phenotypes of E. coli strains translocate more frequently than others, suggesting that they have properties facilitating translocation.