AMP-dependent phosphite dehydrogenase, a phosphorylating enzyme in dissimilatory phosphite oxidation

Oxidation of phosphite (HPO32-) to phosphate (HPO42-) releases electrons at a very low redox potential (E0'= -690 mV) which renders phosphite an excellent electron donor for microbial energy metabolism. To date, two pure cultures of strictly anaerobic bacteria have been isolated that run their energy metabolism on the basis of phosphite oxidation, the Gram-negative Desulfotignum phosphitoxidans (DSM 13687) and the Gram-positive Phosphitispora fastidiosa (DSM 112739). Here, we describe the key enzyme for dissimilatory phosphite oxidation in these bacteria. The enzyme catalyzed phosphite oxidation in the presence of adenosine monophosphate (AMP) to form adenosine diphosphate (ADP), with concomitant reduction of oxidized nicotinamide adenine dinucleotide (NAD+) to reduced nicotinamide adenine dinucleotide (NADH). The enzyme of P. fastidiosa was heterologously expressed in Escherichia coli. It has a molecular mass of 35.2 kDa and a high affinity for phosphite and NAD+. Its activity was enhanced more than 100-fold by addition of ADP-consuming adenylate kinase (myokinase) to a maximal activity between 30 and 80 mU x mg protein-1. A similar NAD-dependent enzyme oxidizing phosphite to phosphate with concomitant phosphorylation of AMP to ADP is found in D. phosphitoxidans, but this enzyme could not be heterologously expressed. Based on sequence analysis, these phosphite-oxidizing enzymes are related to nucleotide-diphosphate-sugar epimerases and indeed represent AMP-dependent phosphite dehydrogenases (ApdA). A reaction mechanism is proposed for this unusual type of substrate-level phosphorylation reaction.

Isophthalate:coenzyme A ligase initiates anaerobic degradation of xenobiotic isophthalate

Background

Environmental contamination from synthetic plastics and their additives is a widespread problem. Phthalate esters are a class of refractory synthetic organic compounds which are widely used in plastics, coatings, and for several industrial applications such as packaging, pharmaceuticals, and/or paints. They are released into the environment during production, use and disposal, and some of them are potential mutagens and carcinogens. Isophthalate (1,3-benzenedicarboxylic acid) is a synthetic chemical that is globally produced at a million-ton scale for industrial applications and is considered a priority pollutant. Here we describe the biochemical characterization of an enzyme involved in anaerobic degradation of isophthalate by the syntrophically fermenting bacterium Syntrophorhabdus aromaticivorans strain UI that activate isophthalate to isophthalyl-CoA followed by its decarboxylation to benzoyl-CoA.

Results

Isophthalate:Coenzyme A ligase (IPCL, AMP-forming) that activates isophthalate to isophthalyl-CoA was heterologously expressed in E. coli (49.6 kDa) for biochemical characterization. IPCL is homologous to phenylacetate-CoA ligase that belongs to the family of ligases that form carbon-sulfur bonds. In the presence of coenzyme A, Mg²⁺ and ATP, IPCL converts isophthalate to isophthalyl-CoA, AMP and pyrophosphate (PPi). The enzyme was specifically induced after anaerobic growth of S. aromaticivorans in a medium containing isophthalate as the sole carbon source. Therefore, IPCL exhibited high substrate specificity and affinity towards isophthalate. Only substrates that are structurally related to isophthalate, such as glutarate and 3-hydroxybenzoate, could be partially converted to the respective coenzyme A esters. Notably, no activity could be measured with substrates such as phthalate, terephthalate and benzoate. Acetyl-CoA or succinyl-CoA did not serve as CoA donors. The enzyme has a theoretical pI of 6.8 and exhibited optimal activity between pH 7.0 to 7.5. The optimal temperature was between 25 °C and 37 °C. Denaturation temperature (Tm) of IPCL was found to be at about 63 °C. The apparent K_M values for isophthalate, CoA, and ATP were 409 μM, 642 μM, and 3580 μM, respectively. Although S. aromaticivorans is a strictly anaerobic bacterium, the enzyme was found to be oxygen-insensitive and catalysed isophthalyl-CoA formation under both anoxic and oxic conditions.

Conclusion

We have successfully cloned the ipcl gene, expressed and characterized the corresponding IPCL enzyme, which plays a key role in isophthalate activation that initiates its activation and further degradation by S. aromaticivorans. Its biochemical characterization represents an important step in the elucidation of the complete degradation pathway of isophthalate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02630-x.

Phosphitispora fastidiosa gen. nov. sp. nov., a new dissimilatory phosphite-oxidizing anaerobic bacterium isolated from anaerobic sewage sludge

A new strictly anaerobic bacterium, strain DYL19^T, was enriched and isolated with phosphite as the sole electron donor and CO₂ as a single carbon source and electron acceptor from anaerobic sewage sludge sampled at a sewage treatment plant in Constance, Germany. It is a Gram-positive, spore-forming, slightly curved, rod-shaped bacterium which oxidizes phosphite to phosphate while reducing CO₂ to biomass and small amounts of acetate. Optimal growth is observed at 30 °C, pH 7.2, with a doubling time of 3 days. Beyond phosphite, no further inorganic or organic electron donor can be used, and no other electron acceptor than CO₂ is reduced. Sulphate inhibits growth with phosphite and CO₂. The G+C content is 45.95 mol%, and dimethylmenaquinone-7 is the only quinone detectable in the cells. On the basis of 16S rRNA gene sequence analysis and other chemotaxonomic properties, strain DYL19^T is described as the type strain of a new genus and species, Phosphitispora fastidiosa gen. nov., sp. nov.

First-line surgery in prolactinomas: lessons from a long-term follow-up study in a tertiary referral center

CONTEXT

Although consensus guidelines recommend dopamine agonists (DAs) as the first-line approach in prolactinomas, some patients may opt instead for upfront surgery, with the goal of minimizing the need for continuation of DAs over the long term. While this approach can be recommended in selected patients with a microprolactinoma, the indication for upfront surgery in macroprolactinomas remains controversial, with limited long-term data in large cohorts. We aimed at elucidating whether first-line surgery is equally safe and effective for patients with micro- or macroprolactinomas not extending beyond the median carotid line (i.e., Knosp grade ≤ 1).

METHODOLOGY

Retrospective study of patients with prolactinomas Knosp grade ≤ 1 treated with upfront surgery. The primary endpoint was patients' dependence on DAs at last follow-up. The secondary endpoint was postoperative complications. Independent risk factors for long-term dependence on DAs were analyzed.

RESULTS

A microadenoma was noted in 45 patients (52%) and a macroadenoma in 41 (48%), with 17 (20%) harboring a Knosp grade 1 prolactinoma. Median follow-up was 80 months. First-line surgery resulted in long-term remission in 31 patients (72%) with a microprolactinoma and in 18 patients (45%) with a macroprolactinoma (p = 0.02). DA therapy was ultimately required in 11 patients (24%) with microadenomas vs. 20 (49%) with macroadenomas (p = 0.03). As for the latter, DA was required in 13 patients (76%) with Knosp grade 1 macroadenomas vs. 7 patients (29%) with Knosp grade 0 macroadenomas (p = 0.004). There was no mortality, and morbidity was minimal. Knosp grade 1 prolactinomas (OR 7.3, 95% CI 1.4-37.7, p = 0.02) but not adenoma size (i.e., macroprolactinomas) were an independent predictor of long-term dependence on DAs.

CONCLUSIONS

First-line surgery in patients with microprolactinomas or macroprolactinomas Knosp grade 0 resulted in a good chance of non-dependency on DA therapy. However, in patients with prolactinomas Knosp grade 1, first-line surgery cannot be recommended, as adjuvant DA therapy after surgery is required in the majority of them over the long term.

Sialoglycans on lymphatic endothelial cells augment interactions with Siglec-1 (CD169) of lymph node macrophages

Cellular interactions between endothelial cells and macrophages regulate macrophage localization and phenotype, but the mechanisms underlying these interactions are poorly understood. Here we explored the role of sialoglycans on lymphatic endothelial cells (LEC) in interactions with macrophage-expressed Siglec-1 (CD169). Lectin-binding assays and mass spectrometric analyses revealed that LEC from human skin express more sialylated glycans than the corresponding blood endothelial cells. Higher amounts of sialylated and/or sulfated glycans on LEC than BEC were consistently observed in murine skin, lung and lymph nodes. The floor LEC of the subcapsular sinus (SCS) in murine lymph nodes (LN) displayed sialylated glycans at particularly high densities. The sialoglycans of LN LEC were strongly bound by Siglec-1. Such binding plays an important role in the localization of Siglec-1⁺ LN-SCS macrophages, as their numbers are strongly reduced in mice expressing a Siglec-1 mutant that is defective in sialoglycan binding. The residual Siglec-1⁺ macrophages are less proliferative and have a more anti-inflammatory phenotype. We propose that the densely clustered, sialylated glycans on the SCS floor LEC are a key component of the macrophage niche, providing anchorage for the Siglec-1⁺ LN-SCS macrophages.

Activation of short-chain ketones and isopropanol in sulfate-reducing bacteria

BACKGROUND

Degradation of acetone by aerobic and nitrate-reducing bacteria can proceed via carboxylation to acetoacetate and subsequent thiolytic cleavage to two acetyl residues. A different strategy was identified in the sulfate-reducing bacterium Desulfococcus biacutus that involves formylation of acetone to 2-hydroxyisobutyryl-CoA.

RESULTS

Utilization of short-chain ketones (acetone, butanone, 2-pentanone and 3-pentanone) and isopropanol by the sulfate reducer Desulfosarcina cetonica was investigated by differential proteome analyses and enzyme assays. Two-dimensional protein gel electrophoresis indicated that D. cetonica during growth with acetone expresses enzymes homologous to those described for Desulfococcus biacutus: a thiamine diphosphate (TDP)-requiring enzyme, two subunits of a B₁₂-dependent mutase, and a NAD⁺-dependent dehydrogenase. Total proteomics of cell-free extracts confirmed these results and identified several additional ketone-inducible proteins. Acetone is activated, most likely mediated by the TDP-dependent enzyme, to a branched-chain CoA-ester, 2-hydroxyisobutyryl-CoA. This compound is linearized to 3-hydroxybutyryl-CoA by a coenzyme B₁₂-dependent mutase followed by oxidation to acetoacetyl-CoA by a dehydrogenase. Proteomic analysis of isopropanol- and butanone-grown cells revealed the expression of a set of enzymes identical to that expressed during growth with acetone. Enzyme assays with cell-free extract of isopropanol- and butanone-grown cells support a B₁₂-dependent isomerization. After growth with 2-pentanone or 3-pentanone, similar protein patterns were observed in cell-free extracts as those found after growth with acetone.

CONCLUSIONS

According to these results, butanone and isopropanol, as well as the two pentanone isomers, are degraded by the same enzymes that are used also in acetone degradation. Our results indicate that the degradation of several short-chain ketones appears to be initiated by TDP-dependent formylation in sulfate-reducing bacteria.

Exploitation of network-segregated CPU resources in CMS

CMS is tackling the exploitation of CPU resources at HPC centers where compute nodes do not have network connectivity to the Internet. Pilot agents and payload jobs need to interact with external services from the compute nodes: access to the application software (CernVM-FS) and conditions data (Frontier), management of input and output data files (data management services), and job management (HTCondor). Finding an alternative route to these services is challenging. Seamless integration in the CMS production system without causing any operational overhead is a key goal. The case of the Barcelona Supercomputing Center (BSC), in Spain, is particularly challenging, due to its especially restrictive network setup. We describe in this paper the solutions developed within CMS to overcome these restrictions, and integrate this resource in production. Singularity containers with application software releases are built and pre-placed in the HPC facility shared file system, together with conditions data files. HTCondor has been extended to relay communications between running pilot jobs and HTCondor daemons through the HPC shared file system. This operation mode also allows piping input and output data files through the HPC file system. Results, issues encountered during the integration process, and remaining concerns are discussed.

The manifold roles of sialic acid for the biological functions of endothelial glycoproteins

Vascular endothelia are covered with a dense glycocalix that is heavily sialylated. Sialylation of vascular glycoconjugates is involved in the regulation of cell-cell interactions, be it among endothelial cells at cell junctions or between endothelial and blood-borne cells. It also plays important roles in modulating the binding of soluble ligands and the signaling by vascular receptors. Here, we provide an overview over the sialylation-function relationships of glycoproteins expressed in the blood and lymphatic vasculature. We first describe cellular interactions in which sialic acid contributes in a stereospecific manner to glycan epitopes recognized by glycan-binding proteins. Our major focus is however on the rarely discussed examples of vascular glycoproteins whose biological functions are modulated by sialylation through other mechanisms.

Biomimetic reconstruction of the hematopoietic stem cell niche for in vitro amplification of human hematopoietic stem cells

Hematopoietic stem cell transplantation is successfully applied since the late 1950s; however, its efficacy still needs to be increased. A promising strategy is to transplant high numbers of pluripotent hematopoietic stem cells (HSCs). Therefore, an improved ex vivo culture system that supports proliferation and maintains HSC pluripotency would override possible limitations in cell numbers gained from donors. To model the natural HSC niche in vitro, we optimized the HSC medium composition with a panel of cytokines and valproic acid and used an artificial 3D bone marrow-like scaffold made of polydimethylsiloxane (PDMS). This 3D scaffold offered a suitable platform to amplify human HSCs in vitro and, simultaneously, to support their viability, multipotency and ability for self-renewal. Silicon oxide-covering of PDMS structures further improved amplification of CD34+ cells, although the conservation of naïve HSCs was better on non-covered 3D PDMS. Finally, we found that HSC cultivated on non-covered 3D PDMS generated most pluripotent colonies within colony forming unit assays. In conclusion, by combining biological and biotechnological approaches, we optimized in vitro HSCs culture conditions, resulting in improved amplification, multipotency maintenance and vitality of HSCs.

High risk of permanent stoma after anastomotic leakage in anterior resection for rectal cancer

AIM

This study investigates how often bowel continuity was restored after anastomotic leakage in anterior resection for rectal cancer and assesses the clinical factors associated with permanent stoma.

METHOD

The Swedish Colorectal Cancer Registry was used to identify cases of anastomotic leakage registered in southern Sweden between January 2001 and December 2011. Patient characteristics, surgical details and clinical information about the anastomotic leakages were retrieved from medical records.

RESULTS

Of the 1442 patients operated on with anterior resection in 11 hospitals, 144 (10%) were diagnosed with anastomotic leakage after anterior resection for rectal cancer. After a median follow-up of 87 months (range 21-165), the overall rate of permanent stoma among patients with anastomotic leakage was 65%. Age ≥ 70 years (P = 0.02) and re-laparotomy (P < 0.001) were independently related to permanent stoma. Compared with nondefunctioned patients with anastomotic leakage, defunctioned patients with anastomotic leakage at the index procedure less often required re-laparotomy at some point during the entire clinical course (P < 0.001), but nondefunctioned and defunctioned patients with anastomotic leakage both had permanent stoma to the same extent (67% and 62%, respectively).

CONCLUSION

Anastomotic leakage is highly associated with permanent stoma after anterior resection, especially in patients aged ≥ 70 years. In this cohort of patients with anastomotic leakage, 65% had permanent stoma at long-term follow-up. A defunctioning stoma ameliorates the clinical course but does not affect the end result of bowel continuity in established anastomotic leakage after anterior resection.

Causes of mortality and morbidity in free-ranging mustelids in Switzerland: necropsy data from over 50 years of general health surveillance

BACKGROUND

Although mustelids occur worldwide and include a wide range of species, little is known about the diseases affecting them. Mustelids have regularly been submitted for post mortem investigation in the framework of the program for general wildlife health surveillance in Switzerland, which has been in place for nearly 60 years. We performed a retrospective analysis of the necropsy reports on mustelids submitted to the diagnostic service of the University of Bern. The aims of this study were to present an overview of the causes of mortality and morbidity observed in these carnivores, to assess differences among species, to assess changes in disease detection over the study period, and to describe the pathology of selected diseases.

RESULTS

Five hundred and sixty-six reports from 1958 to 2015 were analyzed. Most animals were stone martens (Martes foina, 46%) and badgers (Meles meles, 44%); the remaining species were polecats (Mustela putorius, 4.7%), pine martens (Martes martes, 2%), stoats (Mustela erminea, 1.4%), weasels (Mustela nivalis, 0.8%) and otters (Lutra lutra, 0.3%). Infectious diseases (n = 262) were frequent and were mostly bacterial or viral; non-infectious conditions (n = 169) were less common and were mostly traumatic or due to metabolic disorders. The most frequent diagnoses included distemper (75% were badgers), amyloidosis (96% were martens), bacterial respiratory infections (all mustelids), biting lice (badgers only) and pulmonary and gastro-intestinal helminths (all species). Less frequent diseases included histoplasmosis (badgers only), aspergillosis, toxoplasmosis, hepatozoonosis, and sarcoptic mange. Lesions due to infection with distemper virus were primarily appreciated in the respiratory tract and central nervous system; they presented species-specific characteristics such as necrosis in the ependyma in badgers and absence of syncytia in stone martens. Amyloidosis in martens was multisystemic in most cases and included both AA and AL amyloidosis; the main macroscopic change was severe splenomegaly.

CONCLUSION

Infectious diseases were the most frequent causes of morbidity and mortality of mustelids, with marked species-specific differences. Lung and skin were the most commonly affected organs. Contagious diseases such as canine distemper, sarcoptic mange and rabies in mustelids showed a similar temporal pattern as in red foxes (Vulpes vulpes), suggesting pathogen spillovers from foxes to mustelids.

Late leakage after anterior resection: a defunctioning stoma alters the clinical course of anastomotic leakage

AIM

Anastomotic leakage (AL) is common after anterior resection (AR). Long term clinical outcomes of AL including late presenting leakage (LL) are not well studied. This study was undertaken to assess clinical features of LL with respect to incidence, association with predisposing factors and need for re-intervention.

METHODS

The Swedish Colorectal Cancer Registry (SCRCR) was explored for AL cases after AR for rectal cancer in patients operated in the south of Sweden from 1 January 2001 to 31 December 2011. Demographic data, surgical technical details, number of postoperative days (POD) until diagnosis of AL, presenting symptoms, methods of diagnosis and treatment were retrieved from medical records. LL was defined according to different cut-offs as leakages occurring after hospital discharge (LLAHD), after 30 POD (LL ≥ POD 30) and after 90 POD (LL ≥ POD 90).

RESULTS

In total, 1442 patients were operated on with AR of whom 144 cases of AL (10%) were identified. Median time from operation to follow-up was 87 months (range 21-162). LLAHD, LL ≥ POD 30 and LL ≥ POD 90 were present in 51%, 24% and 9% respectively. All categories of LL were associated with a defunctioning stoma. Relaparotomy was significantly less often employed in LLAHD, but not in other categories of LL.

CONCLUSION

LL constitutes a substantial portion of all AL after AR for rectal cancer. The large proportion of LLAHD calls for awareness in the outpatient setting.

In vivo selection of a multidrug-resistant Aeromonas salmonicida during medicinal leech therapy

We report the selection in a 15-year-old boy of a multidrug-resistant, extended-spectrum β-lactamase (ESBL)-producing Aeromonas salmonicida after medicinal leech therapy that required an antibiotic prophylaxis based on piperacillin/tazobactam and cotrimoxazole. Whole genome sequencing of the strain indeed revealed 13 antibiotic resistance genes, including the ESBL CTX-M-3 and the unusual β-lactamase SCO-1.

Aeromonas salmonicida type III secretion system-effectors-mediated immune suppression in rainbow trout (Oncorhynchus mykiss)

Aeromonas salmonicida subsp. salmonicida, the etiologic agent of furunculosis, is a major pathogen in aquaculture. Together with other pathogens, it is characterized by the presence of a type 3 secretion system (T3SS). The T3SS is the main virulence mechanism of A. salmonicida. It is used by the bacterium to secrete and translocate several toxins and effector proteins into the host cell. Some of these factors have a detrimental impact on the integrity of the cell cytoskeleton, likely contributing to impair phagocytosis. Furthermore, it has been suggested that effectors of the T3SS are able to modulate the host's immune response. Here we present the first partial characterization of the immune response in rainbow trout (Oncorhynchus mykiss) infected with distinct strains of A. salmonicida either carrying (i) a fully functional T3SS or (ii) a functionally impaired T3SS or (iii) devoid of T3SS ("cured" strain). Infection with an A. salmonicida strain either carrying a fully functional or a secretion-impaired T3SS was associated with a strong and persistent immune suppression. However, the infection appeared to be fatal only in the presence of a fully functional T3SS. In contrast, the absence of T3SS was neither associated with immune suppression nor fish death. These findings suggest that the T3SS and T3SS-delivered effector molecules and toxins of A. salmonicida do not only impair the host cells' cytoskeleton thus damaging cell physiology and phagocytosis, but also heavily affect the transcription of critical immune mediators including the shut-down of important warning signals to recognize infection and induce immune defense.

Cloning, functional expression and characterization of a bifunctional 3-hydroxybutanal dehydrogenase /reductase involved in acetone metabolism by Desulfococcus biacutus

Background

The strictly anaerobic, sulfate-reducing bacterium Desulfococcus biacutus can utilize acetone as sole carbon and energy source for growth. Whereas in aerobic and nitrate-reducing bacteria acetone is activated by carboxylation with CO₂ to acetoacetate, D. biacutus involves CO as a cosubstrate for acetone activation through a different, so far unknown pathway. Proteomic studies indicated that, among others, a predicted medium-chain dehydrogenase/reductase (MDR) superfamily, zinc-dependent alcohol dehydrogenase (locus tag DebiaDRAFT_04514) is specifically and highly produced during growth with acetone.

Results

The MDR gene DebiaDRAFT_04514 was cloned and overexpressed in E. coli. The purified recombinant protein required zinc as cofactor, and accepted NADH/NAD⁺ but not NADPH/NADP⁺ as electron donor/acceptor. The pH optimum was at pH 8, and the temperature optimum at 45 °C. Highest specific activities were observed for reduction of C₃ - C₅-aldehydes with NADH, such as propanal to propanol (380 ± 15 mU mg⁻¹ protein), butanal to butanol (300 ± 24 mU mg⁻¹), and 3-hydroxybutanal to 1,3-butanediol (248 ± 60 mU mg⁻¹), however, the enzyme also oxidized 3-hydroxybutanal with NAD⁺ to acetoacetaldehyde (83 ± 18 mU mg⁻¹).

Conclusion

The enzyme might play a key role in acetone degradation by D. biacutus, for example as a bifunctional 3-hydroxybutanal dehydrogenase/reductase. Its recombinant production may represent an important step in the elucidation of the complete degradation pathway.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-016-0899-9) contains supplementary material, which is available to authorized users.

Seroprevalence of Leptospira spp. in clinically healthy horses in Switzerland

A retrospective, cross-sectional study was conducted to determine the leptospiral seroprevalence in clinically healthy horses in Switzerland. A representative sample of 615 horse sera was examined by microscopic agglutination test for the presence of antibodies against 15 Leptospira spp. serovars. In total, 58.5 % (n = 360) of the horses were positive for one or more of the antigens analysed, with 20.3 % of them showing titres >= 400. The most prevalent serovar was Pyrogenes (22.6 %), followed by serovars Canicola (22.1 %) and Australis (19.2 %). Older horses, mares, ponies and animals spending increased time on pasture exhibited significantly higher prevalence rates (p < 0.05). Moreover, the prevalence was higher in summer and autumn (p = 0.003). The high seroprevalence in healthy horses indicates that they are often exposed to or infected with Leptospira spp. without developing signs of disease. Therefore, other laboratory and clinical data should always be taken into consideration when interpreting serological test results for Leptospira spp.

Activation of Acetone and Other Simple Ketones in Anaerobic Bacteria

Acetone and other ketones are activated for subsequent degradation through carboxylation by many nitrate-reducing, phototrophic, and obligately aerobic bacteria. Acetone carboxylation leads to acetoacetate, which is subsequently activated to a thioester and degraded via thiolysis. Two different types of acetone carboxylases have been described, which require either 2 or 4 ATP equivalents as an energy supply for the carboxylation reaction. Both enzymes appear to combine acetone enolphosphate with carbonic phosphate to form acetoacetate. A similar but more complex enzyme is known to carboxylate the aromatic ketone acetophenone, a metabolic intermediate in anaerobic ethylbenzene metabolism in denitrifying bacteria, with simultaneous hydrolysis of 2 ATP to 2 ADP. Obligately anaerobic sulfate-reducing bacteria activate acetone to a four-carbon compound as well, but via a different process than bicarbonate- or CO2-dependent carboxylation. The present evidence indicates that either carbon monoxide or a formyl residue is used as a cosubstrate, and that the overall ATP expenditure of this pathway is substantially lower than in the known acetone carboxylase reactions.

Listeria monocytogenes infection in ruminants: Is there a link to the environment, food and human health? A review

Listeria (L.) monocytogenes is widely distributed in the environment, but also has the ability to cause serious invasive disease in ruminants and humans. This review provides an overview of listeriosis in ruminants and discusses our insufficient understanding of reservoirs and possible cycling ofL. monocytogenes between animal and human hosts, food and the environment. It indicates gaps in our knowledge of the role of genetic subtypes in L. monocytogenes ecology and virulence as well as risk factors, in vivo diagnostics and pathogenesis of listeriosis in ruminants. Filling these gaps will contribute to improving the control of L. monocytogenes and enhancing disease prevention. As the prevalence of listeriosis in ruminants in Switzerland is likely to be underestimated, propositions concerning improvement options for surveillance of listeriosis in ruminants are provided.

Occurrence of Brachyspira hyodysenteriae in multiplier pig herds in Switzerland

OBJECTIVE

This research was aimed to determine the occurrence of Brachyspira (B.) hyodysenteriae in Swiss multiplier pig herds.

MATERIALS AND METHODS

In a pilot study a direct real-time polymerase chain reaction (PCR) method for B. hyodysenteriae was compared to culture followed by PCR on 106 samples from three herds. Subsequently 40 multiplier herds were epidemiologically characterized and analysed for the presence of B. hyodysenteriae using direct PCR on 1412 rectal swabs. For external validation 20 swabs obtained from two positive conventional herds were analysed.

RESULTS

The comparison of direct PCR with culture followed by PCR resulted in a moderate agreement (kappa index: 0.58). In the two conventional herds, 35% of the samples (7/20) tested positive. Samples from 39 multipliers tested negative. In one multiplier herd, 25% (9/36) of the samples tested PCR positive. Risk factors in the multiplier herd may have been rodents or birds, but not pig purchase.

CONCLUSION AND CLINICAL RELEVANCE

B. hyodysenteriae have been detected in a Swiss multiplier herd, which underlines the threat of potential spread by replacement pigs. Consequently, a Brachyspira monitoring programme was established for Swiss multiplier herds.

Relation of intraoperative temperature to postoperative mortality in open colon surgery--an analysis of two randomized controlled trials

INTRODUCTION

The open surgical wound is exposed to cold and dry ambient air resulting in heat loss mainly through radiation and convection. This cools the wound and promotes local vasoconstriction and hypoxia. Carbon dioxide (CO2) and water vapor are greenhouse gases with a warming effect. The aim was to evaluate if warm humidified CO2 insufflated in surgical wound can affect long-term overall mortality

METHODS

This is a retrospective study of two clinical trials, where patients were randomized to warm humidified CO2 (n = 80) or not (n = 78). All patients underwent elective major open colon surgery. Patients in the treatment group received insufflation of warm humidified CO2 into the open wound cavity via a gas diffuser to create a local atmosphere of 100% CO2. Temperature in the wound cavity was measured with a heat-sensitive infrared camera. Core temperature was measured at the tympanic membrane. Median follow-up was 70.9 months.

RESULTS

A multivariate analysis adjusted for age (p = 0.001) and cancer (p = 0.165) showed that the larger the temperature difference between final core temperature and wound edge temperature, the lower the overall survival rate (p = 0.050). Patients receiving insufflation of warm humidified CO2 had a tendency to a better overall survival compared with control patients (p = 0.508). End-of-operation wound edge temperature was negatively associated with mortality (OR = 0.80, 95% CI = 0.68-0.95, p = 0.011), whereas mortality was positively associated with age (10-year increase, OR = 1.78, 95% CI = 1.37-2.33, p < 0.001) and cancer (OR = 8.1, 95% CI = 1.95-33.7, p = 0.004).

CONCLUSIONS

A small end-of-operation temperature difference between final core and wound edge temperature was positively associated with patient survival in open colon surgery.

Outbreak investigation identifies a single Listeria monocytogenes strain in sheep with different clinical manifestations, soil and water

Listeria (L.) monocytogenes causes orally acquired infections and is of major importance in ruminants. Little is known about L. monocytogenes transmission between farm environment and ruminants. In order to determine potential sources of infection, we investigated the distribution of L. monocytogenes genetic subtypes in a sheep farm during a listeriosis outbreak by applying four subtyping methods (MALDI-TOF-MS, MLST, MLVA and PFGE). L. monocytogenes was isolated from a lamb with septicemia and from the brainstem of three sheep with encephalitis. Samples from the farm environment were screened for the presence of L. monocytogenes during the listeriosis outbreak, four weeks and eight months after. L. monocytogenes was found only in soil and water tank swabs during the outbreak. Four weeks later, following thorough cleaning of the barn, as well as eight months later, L. monocytogenes was absent in environmental samples. All environmental and clinical L. monocytogenes isolates were found to be the same strain. Our results show that the outbreak involving two different clinical syndromes was caused by a single L. monocytogenes strain and that soil and water tanks were potential infection sources during this outbreak. However, silage cannot be completely ruled out as the bales fed prior to the outbreak were not available for analysis. Faeces samples were negative, suggesting that sheep did not act as amplification hosts contributing to environmental contamination. In conclusion, farm management appears to be a crucial factor for the limitation of a listeriosis outbreak.

Characterisation of a new group of Francisella tularensis subsp. holarctica in Switzerland with altered antimicrobial susceptibilities, 1996 to 2013

Molecular analysis of Francisella tularensis subsp. holarctica isolates from humans and animals revealed the presence of two subgroups belonging to the phylogenetic groups B.FTNF002-00 and B.13 in Switzerland. This finding suggests a broader spread of this group in Europe than previously reported. Until recently, only strains belonging to the Western European cluster (group B.FTNF002-00) had been isolated from tularaemia cases in Switzerland. The endemic strains belonging to group B.FTNF002-00 are sensitive to erythromycin, in contrast to the strains of the newly detected group B.13 that are resistant to this antibiotic. All the strains tested were susceptible to ciprofloxacin, streptomycin, gentamicin, nalidixic acid and chloramphenicol but showed reduced susceptibility to tetracycline when tested in a growth medium supplemented with divalent cations. The data show a previously undetected spread of group B.13 westwards in Europe, associated with changes in the antibiotic resistance profile relevant to treatment of tularaemia.

Survey of animal bite injuries and their management for an estimate of human rabies deaths in N'Djaména, Chad

OBJECTIVE

To estimate the annual human rabies incidence as a baseline prior to mass dog vaccination campaigns in N'Djaména, Chad.

METHODS

Survey of animal bites, involving 50% of all healthcare providers in N'Djaména, from September 2008 to April 2009. Of 86 people exposed to a suspected rabid animal, 50% received post-exposure vaccination and a further 8% had their wound cleaned. We estimated annual incidence of bites from suspected rabid animals of 12.9/100,000 and an incidence of 0.7 human rabies deaths/100,000, resulting in 7 estimated deaths (95% confidence interval 4-10 deaths) per year in N'Djaména. 14% of bite victims sought help from veterinarians.

CONCLUSIONS

Closer cooperation between physicians and veterinarians warrants more effective rabies control. The high proportion (42%) of potentially exposed people without post-exposure vaccination or wound treatment necessitates urgent attention.

Vergleich der antimikrobiellen Resistenz von ausgewählten Infektionserregern des Respirationstraktes bei verschiedenen Tierarten

The antibiotic resistance pattern of respiratory tract pathogens isolated of different animal species suffering from respiratory tract diseases has been investigated by antibiograms performed by agar diffusion test. The results show that the resistance situation in Switzerland is favourable compared with studies from other countries. However, high resistance rates were found in certain species: 61% of Streptococcus spp. were resistant to erythromycin and 44% to tetracycline, 59% of Bordetella bronchiseptica were resistant to ampicillin and 50% of Mannheimia (Pasteurella) haemolytica were multiresistant to tetracycline, ampicillin and streptomycine. The gram negative isolates were widely resistant to streptomycine.

Equine botulism and acute pasture myodystrophy: New soil-borne emerging diseases in Switzerland?

In Switzerland, the incidence of equine botulism and acute pasture myodystrophy have remarkably increased in the last five years. Equine fodder-borne botulism in Europe is most likely caused by Clostridium botulinum types C and D that produce the toxins BoNT/C and BoNT/D. Horses showing signs suggestive of botulism (muscle weakness and tremors, reduced tongue tone, slow chewing, salivation and difficulties swallowing, drooping eyelids, mydriasis), especially patients that have fed on suspect fodder (mostly haylage), must be treated with anti-serum as soon as possible. They also need intensive care, which is often difficult to provide and always expensive in the face of a guarded to poor prognosis. Therefore, prevention (high standards of forage quality and vaccination) is all the more important. Pasture myodystrophy is an acute disease with signs of rhabdomyolysis and lethality rate over 90%. It affects grazing horses under frosty, windy and rainy conditions. Preliminary results indicate that Clostridium sordellii and Clostridium bifermentans producing lethal toxin may play a role in pasture myodystrophy. Our efforts concentrate on developing a new subunit vaccine for equine botulism and understanding the ethiology and pathogenesis of pasture myodystrophy with the goal of improving prevention against these highly fatal diseases that present a significant risk to our horse population.

Detection of Mycoplasma conjunctivae in sheep affected with conjunctivitis and infectious keratoconjunctivitis

AIM

To determine the aetiology of a recurring and severe form of infectious keratoconjunctivitis (IKC) in sheep.

METHODS

Five sheep flocks that had experienced a severe form of IKC were examined. Clinical history, conjunctival swabs and blood samples were collected from affected animals. Culture for bacteria, and also specifically for Mycoplasma and Chlamydophila spp, and detection of Mycoplasma conjunctivae DNA by polymerase chain reaction (PCR) were attempted. Serum samples were tested for antibodies to M. agalactiae, M. capricolum, M. conjunctivae and Chlamydophila spp.

RESULTS

Mycoplasma conjunctivae DNA was detected using PCR in 3/5 flocks, and in all flocks antibodies to M. conjunctivae were detected in sera. A pure growth of Branhamella ovis was cultured from conjunctival swabs from a small proportion of sheep in two flocks. No other pathogens were detected.

CONCLUSIONS

This investigation demonstrated that M. conjunctivae was a primary pathogen causing severe IKC in sheep, and is the first report of detection of this organism in sheep in New Zealand. Introduction of clinically normal carrier sheep appeared to have caused the outbreaks.

KEYWORDS

Infectious keratoconjunctivitis, Mycoplasma conjunctivae, Chlamydophila pecorum, Branhamella ovis, polymerase chain reaction, ELISA, complement fixation test.

Risk of Vibrio transmission linked to the consumption of crustaceans in coastal towns of Côte d'Ivoire

The purpose of this study was to assess the risk of Vibrio spp. transmission from crustaceans to humans in two coastal towns of Côte d'Ivoire. Bacteriologic analysis was performed on 322 crustacean samples obtained from six markets in Abidjan and one in Dabou. Suspected Vibrio colonies were identified by morphological, cultural, biochemical, and molecular tests and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. PCR assays were used to further characterize Vibrio strains. A survey on consumption of crustaceans was conducted among 120 randomly selected households in Abidjan. Overall, Vibrio spp. were isolated from 7.8% of the crustacean samples studied, at levels as high as 6.3 log CFU/g. Of the Vibrio strains identified, 40% were V. alginolyticus, 36% were V. parahaemolyticus, and 24% were nontoxigenic V. cholerae; the latter two species can cause mild to severe forms of seafood-associated gastroenteritis. Among interviewed households, 11.7% reported daily consumption of crustaceans, confirming the high probability of exposure of human population to Vibrio spp., and 7.5% reported symptoms of food poisoning after consumption of crustaceans. The absence of genes encoding major virulence factors in the studied strains, i.e., cholera toxin (ctxA and ctxB) in V. cholerae and thermostable direct hemolysin (tdh) and thermostable direct hemolysin-related hemolysin (trh) in V. parahaemolyticus, does not exclude the possibility of exposure to pathogenic strains. However, human infections are not common because most households (96.7%) boil crustaceans, usually for at least 45 min (85.9% of households) before consumption.

Is the alpine divide becoming more permeable to biological invasions? - Insights on the invasion and establishment of the Walnut Husk Fly, Rhagoletis completa (Diptera: Tephritidae) in Switzerland

The Walnut Husk Fly, Rhagoletis completa Cresson (Diptera: Tephritidae), is native to North America (Midwestern US and north-eastern Mexico) and has invaded several European countries in the past decades by likely crossing the alpine divide separating most parts of Switzerland from Italy. Here, we determined its current distribution in Switzerland by sampling walnuts (Juglans regia L.) in ecologically and climatically distinct regions along potential invasion corridors. R. completa was found to be firmly established in most low altitude areas of Switzerland where walnuts thrive, but notably not a single parasitoid was recovered from any of the samples. Infested fruit was recovered in 42 of the 71 localities that were surveyed, with mean fruit infestation rate varying greatly among sites. The incidence of R. completa in Switzerland is closely related to meteorological mean spring temperature patterns influencing growing season length, but not to winter temperatures, reflecting survival potential during hibernation. Importantly, areas in which the fly is absent correspond with localities where the mean spring temperatures fall below 7°C. Historical data records show that the natural cold barrier around the Alpine divide in the central Swiss Alps corresponding to such minimal temperatures has shrunk significantly from a width of more than 40 km before 1990 to around 20 km after 2000. We hypothesize on possible invasion/expansion routes along alpine valleys, dwell on distribution patterns in relation to climate, and outline future research needs as the incursion of R. completa into Switzerland; and, more recently, other European countries, such as Germany, Austria, France and Slovenia, represent an example of alien species that settle first in the Mediterranean Basin and from there become invasive by crossing the Alps.

Outbreaks of an ulcerative and haemorrhagic disease in Arctic char Salvelinus alpinus caused by Aeromonas salmonicida subsp. smithia

Arctic char Salvelinus alpinus farmed in different places in Austria and free of the viral diseases viral haemorrhagic septcaemia (VHS), infectious haematopoietic necrosis (IHN) and infectious pancreatic necrosis (IPN) experienced disease and mortality. Diseased fish showed skin ulceration and pathological signs of sepsis. Aeromonas sp. was isolated as pure culture from the kidney of freshly euthanized diseased fish. Three independent isolates from outbreaks that occurred on 2 of the affected farms were analyzed phylogenetically by DNA sequence analysis of the rrs and gyrB genes and phenotypically with biochemical reactions. All 3 isolates were identified as Aeromonas salmonicida subsp. smithia. Analysis of virulence genes in these isolates revealed the presence of a Type III secretion system as well as several related virulence effector genes including aexT, encoding the Aeromonas exotoxin AexT, aopP and aopH. These genes are characteristic for virulent strains of typical and atypical subspecies of A. salmonicida.

Mycoplasma leachii sp. nov. as a new species designation for Mycoplasma sp. bovine group 7 of Leach, and reclassification of Mycoplasma mycoides subsp. mycoides LC as a serovar of Mycoplasma mycoides subsp. capri

The Mycoplasma mycoides cluster consists of six pathogenic mycoplasmas causing disease in ruminants, which share many genotypic and phenotypic traits. The M. mycoides cluster comprises five recognized taxa: Mycoplasma mycoides subsp. mycoides Small Colony (MmmSC), M. mycoides subsp. mycoides Large Colony (MmmLC), M. mycoides subsp. capri (Mmc), Mycoplasma capricolum subsp. capricolum (Mcc) and M. capricolum subsp. capripneumoniae (Mccp). The group of strains known as Mycoplasma sp. bovine group 7 of Leach (MBG7) has remained unassigned, due to conflicting data obtained by different classification methods. In the present paper, all available data, including recent phylogenetic analyses, have been reviewed, resulting in a proposal for an emended taxonomy of this cluster: (i) the MBG7 strains, although related phylogenetically to M. capricolum, hold sufficient characteristic traits to be assigned as a separate species, i.e. Mycoplasma leachii sp. nov. (type strain, PG50(T) = N29(T) = NCTC 10133(T) = DSM 21131(T)); (ii) MmmLC and Mmc, which can only be distinguished by serological methods and are related more distantly to MmmSC, should be combined into a single subspecies, i.e. Mycoplasma mycoides subsp. capri, leaving M. mycoides subsp. mycoides (MmmSC) as the exclusive designation for the agent of contagious bovine pleuropneumonia. A taxonomic description of M. leachii sp. nov. and emended descriptions of M. mycoides subsp. mycoides and M. mycoides subsp. capri are presented. As a result of these emendments, the M. mycoides cluster will hereafter be composed of five taxa comprising three subclusters, which correspond to the M. mycoides subspecies, the M. capricolum subspecies and the novel species M. leachii.

Pseudomonas chlororaphis strain JF3835 reduces mortality of juvenile perch, Perca fluviatilis L., caused by Aeromonas sobria

Motile aeromonad septicaemia caused by Aeromonas sobria is a cause of disease in farmed perch, Perca fluviatilis L., in Switzerland. We have evaluated the potential of a Pseudomonas chlororaphis isolate, obtained from perch intestine, to control A. sobria infection. Inoculation of juvenile perch with P. chlororaphis strain JF3835 prior to infection with A. sobria caused a reduction in A. sobria associated mortalities. Infection of perch with xylE-labelled P. chlororaphis indicated the bacterium is able to transiently colonize juvenile fish and fingerlings.

Repression of common bull sperm flora and in vitro impairment of sperm motility with Pseudomonas aeruginosa introduced by contaminated lubricant

Semen collected from clinically healthy bulls at an artificial insemination centre was examined for bacterial diversity. While bacteria that are normally present in the common flora of bovine semen were absent, such as Mycoplasma sp., Proteus sp. and Corynebacterium sp., all semen samples contained an unusually high number of Pseudomonas aeruginosa strains. Analysis via pulsed field gel electrophoresis demonstrated that one particular P. aeruginosa strain, present in a sealed bottle of lubricant, was widespread in bull semen. This strain was shown to secrete substances that inhibited both the growth of bacteria constituting the normal bull sperm flora and the motility of spermatozoa in vitro. This study demonstrated that commercially available lubricants might contain bacteria that can spread amongst breeding bulls and affect the quality of semen. Bacteriological controls and species' identification are necessary at several production levels, including lubricants and extenders, to ensure high semen quality and avoid the spread of pathogens.

PCR specific for Actinobacillus pleuropneumoniae serotype 3

Serotypes 3 and 8 of Actinobacillus pleuropneumoniae, the aetiological agent of porcine pleuropneumonia, have been reported to predominate in the UK. Direct serotyping of isolates of the organism is typically determined by the immunological reactivity of rabbit serum to its surface polysaccharides, but the method has limitations, for example, cross-reactions between serotypes 3, 6 and 8. This study describes the development of a serotype 3-specific pcr, based on the capsule locus, which can be used in a multiplex format with the organism's specific gene apxIV. The pcr test was evaluated on 266 strains of A pleuropneumoniae and 121 strains of other organisms, including all the major respiratory bacterial pathogens of pigs. The test was highly specific and sensitive and should be useful for differentiating strains of serotypes 3, 6 and 8, and in seroprevalence and epidemiological surveys in regions where serotype 3 is prevalent, such as the UK.

Novel identification and differentiation of Brucella melitensis, B. abortus, B. suis, B. ovis, B. canis, and B. neotomae suitable for both conventional and real-time PCR systems

We describe the development of a novel PCR assay for the rapid detection of members of the Brucella genus, and the differentiation between six recognized Brucella species. The assay has proven to be highly specific with the additional advantage of being suitable for use with both conventional and real-time PCR.

Identification of bacteria from the normal flora of perch, Perca fluviatilis L., and evaluation of their inhibitory potential towards Aeromonas species

Pathogenic Aeromonas sobria has been identified as a causative agent of ulcerative disease in farmed European perch, Perca fluviatilis L. To study the effect of the normal intestinal bacterial flora of perch against A. sobria, we sampled 193 bacterial isolates from the perch digestive tract. The isolates were identified by sequence analysis of the 16S rRNA gene and their inhibitory potential against A. sobria was evaluated in vitro. Nineteen of the strains isolated showed inhibition and were also tested against other aeromonad and non-aeromonad fish pathogens including Yersinia ruckeri and Vibrio anguillarum. Isolates showing inhibition were primarily Pseudomonas spp.; however, inhibitory Shewanella spp., and Delftia sp. were also identified. A Pseudomonas chlororaphis isolate showed inhibition against all fish pathogens tested.