Methicillin-resistant Staphylococcus aureus (MRSA) is associated with low within-herd prevalence of intra-mammary infections in dairy cows: Genotyping of isolates

Staphylococcus aureus is one of the most common mastitis-causing pathogens worldwide. In the last decade, livestock-associated methicillin-resistant S. aureus (LA-MRSA) infections have been described in several species, included the bovines. Hence, this paper investigates the diffusion of MRSA within Italian dairy herds; the strains were further characterized using a DNA microarray, which detects 330 different sequences, including the methicillin-resistance genes mecA and mecC and SCCmec typing. The analysis of overall patterns allows the assignment to Clonal Complexes (CC). Overall 163 S. aureus isolates, collected from quarter milk samples in 61 herds, were tested. MRSA strains were further processed using spa typing. Fifteen strains (9.2%), isolated in 9 herds (14.75%), carried mecA, but none harboured mecC. MRSA detection was significantly associated (P<0.011) with a within-herd prevalence of S. aureus intra-mammary infections (IMI) ≤5%. Ten MRSA strains were assigned to CC398, the remaining ones to CC97 (n=2), CC1 (n=2) or CC8 (n=1). In 3 herds, MRSA and MSSA co-existed: CC97-MRSA with CC398-MSSA, CC1-MRSA with CC8-MSSA and CC398-MRSA with CC126-MSSA. The results of spa typing showed an overall similar profile of the strains belonging to the same CC: t127-CC1, t1730-CC97, t899 in 8 out of 10 CC398. In the remaining 2 isolates a new spa type, t14644, was identified. The single CC8 was a t3092. The SCCmec cassettes were classified as type IV, type V or type IV/V composite. All or most strains harboured the genes encoding the β-lactamase operon and the tetracycline resistance. Streptogramin resistance gene was related to CC398. Enterotoxin and leukocidin genes were carried only by CC1, CC8 and CC97-MRSA. The persistence of MRSA clones characterized by broader host range, in epidemiologically unrelated areas and in dairy herds with low prevalence of S. aureus IMI, might enhance the risk for adaptation to human species.

Simultaneous identification by multiplex PCR of major Prototheca spp. isolated from bovine and buffalo intramammary infection and bulk tank

Bovine mastitis caused by Prototheca spp. infection is increasing worldwide, therefore becoming more relevant to the dairy industry. Almost all Prototheca isolates from bovine mammary protothecosis came from P. zopfii genotype 2, with a lower prevalence of infection due to P. blaschkeae and rarely to P. wickerhamii. In this study, we report the development of two multiplex PCR assays able to discriminate among the three species responsible for bovine intramammary infection (IMI). Our assay is based on the specific amplification of new DNA target from mitochondria and chloroplasts partial sequences, of different Prototheca isolates. Both methods were set up using reference strains belonging to all Prototheca species and validated by the analysis of 93 isolates from bovine and buffalo IMI and bulk tank milk samples. The investigation involves 70 isolates from North, 13 from Central and 10 from South Italian regions. Isolates from bovine were most commonly identified as P. zopfii genotype 2, and only in one case as P. blaschkeae, whereas isolates from buffaloes belonged both to P. zopfii genotype 2 and P. wickerhamii. These findings proved the suitability of our multiplex PCRs as a rapid test to discriminate among pathogenic Prototheca strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work reports PCR assays based on novel Prototheca spp. mitochondrial and chloroplastic target sequences. The multiplex PCR protocol described in this study is useful for rapid simultaneous detection of P. zopfii, P. wickerhamii and P. blaschkeae.

Identification of virulence factors in 16S-23S rRNA intergenic spacer genotyped Staphylococcus aureus isolated from water buffaloes and small ruminants

Staphylococcus aureus is an important human and animal pathogen, and is regarded as an important cause of intramammary infection (IMI) in ruminants. Staphylococcus aureus genetic variability and virulence factors have been well studied in veterinary medicine, especially in cows as support for control and management of IMI. The aim of the present study was to genotype 71 Staph. aureus isolates from the bulk tank and foremilk of water buffaloes (n=40) and from udder tissue (n=7) and foremilk (n=24) from small ruminants. The method used was previously applied to bovine Staph. aureus and is based on the amplification of the 16S-23S rRNA intergenic spacer region. The technique applied was able to identify different Staph. aureus genotypes isolated from dairy species other than the bovine species, and cluster the genotypes according to species and herds. Virulence gene distribution was consistent with genotype differentiation. The isolates were also characterized through determination of the presence of 19 virulence-associated genes by specific PCR. Enterotoxins A, C, D, G, I, J, and L were associated with Staph. aureus isolates from buffaloes, whereas enterotoxins C and L were linked to small ruminants. Genes coding for methicillin resistance, Panton-Valentine leukocidin, exfoliative toxins A and B, and enterotoxins B, E, and H were undetected. These findings indicate that RNA template-specific PCR is a valid technique for typing Staph. aureus from buffaloes and small ruminants and is a useful tool for understanding udder infection epidemiology.

Evaluation of internal reference genes for quantitative expression analysis by real-time reverse transcription-PCR in somatic cells from goat milk

Reverse transcription (RT) quantitative real-time PCR (qPCR) is the most accurate and easy-to-perform technique to measure the expression level of a selected gene of interest by quantifying mRNA transcripts. The use of reference genes is commonly accepted as the most reliable approach to normalize RT-qPCR data and reduce possible errors generated in the quantification of gene expression. The optimal number and choice of reference genes are experimentally validated for specific tissues or cell types and experimental designs. To date, data on qPCR normalization in goats are scarce and the most suitable reference genes in this species have been identified for only a limited number of tissues. The aim of this study was to determine an optimal combination of stably expressed reference genes in caprine milk somatic cells (MSC) from healthy and infected mammary glands. For the purpose, we performed RT-qPCR for 10 commonly used reference genes from various functional classes and then determined their expression level in MSC from goats intramammary challenged with Staphylococcus aureus and in MSC from healthy controls, with a view to select genes whose stability would be unaffected under infection conditions. The geNorm and NormFinder algorithms were used for validating the reference genes. Furthermore, to demonstrate the importance of normalization of gene expression with appropriate reference genes, we tested the effect of using a combination of the least stable genes for expression analysis evaluation. On the basis of our evaluation, we recommend the use of a panel of reference genes that should include G6PD, YWHAZ, and ACTB for caprine MSC gene expression profiling. The expression of the 2 genes of interest, pentraxin-related protein (PTX3) and secreted phosphoprotein 1 (SPP1), was evaluated by RT-qPCR in all samples collected pre- and postinfection, and the recommended reference genes were used to normalize the data. Our study provides a validated panel of optimal reference genes for the identification of genes differentially expressed by qRT-PCR in caprine MSC. Moreover, we provided a set of intron-spanning primer sequences that could be suitable for gene expression experiments using SYBR Green chemistry on other caprine tissues and cells.

[Coronary stenting and surgery: perioperative management of antiplatelet therapy in patients undergoing surgery after coronary stent implantation]

The management of antiplatelet therapy in patients with coronary stents undergoing surgery is a growing clinical problem and often represents a matter of debate between cardiologists and surgeons. It has been estimated that about 4-8% of patients undergoing coronary stenting need to undergo surgery within the next year. Surgery represents one of the most common reasons for premature antiplatelet therapy discontinuation, which is associated with a significant increase in mortality and major adverse cardiac events, in particular stent thrombosis. In addition, surgery confers an additional risk of perioperative cardiac ischemic events, being high in these patients because of the pro-inflammatory and pro-thrombotic effects of surgery. Current international guidelines recommend to postpone non-urgent surgery for at least 6 weeks after bare metal stent implantation and for 6-12 months after drug-eluting stent implantation. However, these recommendations provide little support with regard to managing antiplatelet therapy in the perioperative phase in case of urgent operations and/or high hemorrhagic risk. Furthermore, ischemic and hemorrhagic risk is not defined in detail on the basis of clinical and procedural characteristics. Finally, guidelines shared with cardiologists and surgeons are lacking. The present consensus document provides practical recommendations on the management of antiplatelet therapy in the perioperative period in patients with coronary stents undergoing surgery. Cardiologists and surgeons contributed equally to its creation. An ischemic risk stratification has been provided on the basis of clinical and procedural data. All surgical interventions have been defined on the basis of the hemorrhagic risk. A consensus on the most appropriate antiplatelet regimen in the perioperative phase has been reached on the basis of the ischemic and hemorrhagic risk. Dual antiplatelet therapy should not be withdrawn for surgery at low bleeding risk, whereas aspirin should be continued perioperatively in the majority of surgical operations. In the event of interventions at high risk for both bleeding and ischemic events, when oral antiplatelet therapy withdrawal is required, perioperative treatment with short-acting intravenous glycoprotein IIb/IIIa inhibitors (tirofiban or eptifibatide) should be considered.

Transcriptome analysis to identify differential gene expression affecting meat quality in heavy Italian pigs

Suppressive subtractive hybridization (SSH) was used to analyse the muscle transcriptome and identify genes affecting meat quality within an Italian pig population of Large White and Landrace purebred individuals. Seven phenotypes were recorded at slaughter: dorsal fat thickness, ham fat thickness, ham fat coverage, muscle compactness, marbling, meat colour and colour uniformity. Two subtractive libraries were created from longissimus dorsi tissue of selected pigs with extreme phenotypes for meat quality. Eighty-four differentially expressed ESTs were identified, which showed homology to expressed pig sequences and/or to genomic pig sequences produced within the pig genome project. Sixty-eight sequences were mapped on the pig genome, and most of these sequences co-localized with the same chromosomal positions as QTLs that have been previously identified for meat quality. Thirty sequences, including eight matching known genes previously related to muscle metabolic pathways, were selected to statistically validate their differential expression. Association analysis and t-test results indicated that 28 ESTs of the 30 analysed were associated with phenotypes investigated here and have significant differential expression levels (P≤ 0.05) between the two tails of the phenotypic distribution.

Prognostic implications of ST-segment elevation resolution in patients with ST-segment elevation acute myocardial infarction treated with primary or facilitated percutaneous coronary intervention

Scant data are available on the relation between ST-segment elevation (STE) resolution and 30-day mortality in patients with STE acute myocardial infarction treated with percutaneous coronary intervention in contemporary, real world, clinical practice. Furthermore, whether the prognostic value of STE resolution is influenced by the patient clinical risk profile or postprocedural Thrombolysis In Myocardial Infarction (TIMI) flow has never been investigated. Lombardima was an observational registry implemented in Lombardy, a Northern Italian region. The clinical characteristics, electorcardiographic parameters, and procedural data were prospectively entered into a Web-based database. In the present study, we enrolled 3,403 patients. STE resolution occurred in 2,452 patients (group 1) and did not in 951 patients (group 2). The mortality rate was 2.4% in group 1 and 11.3% in group 2 (p <0.001). After stratifying patients according to their TIMI risk index, we observed that STE resolution was an independent predictor of 30-day mortality across all spectrum of clinical risk. Furthermore, in patients with TIMI 3 flow, STE resolution remained an independent predictor of 30-day mortality (p <0.0001). In conclusion, STE resolution was a strong and independent predictor of 30-day mortality in patients with STE acute myocardial infarction undergoing percutaneous coronary intervention across all spectrum of clinical risk.

Emergency percutaneous coronary intervention in patients with ST-elevation myocardial infarction complicated by out-of-hospital cardiac arrest: early and medium-term outcome

BACKGROUND

The role of emergency reperfusion therapy in patients with ST-elevation myocardial infarction (STEMI) resuscitated after an out-of-hospital cardiac arrest (OHCA) has not been clearly established yet. The aim of this study was to evaluate the in-hospital and postdischarge outcomes of STEMI patients surviving OHCA and undergoing emergency angioplasty (percutaneous coronary intervention [PCI]) within an established regional network.

METHODS

We prospectively collected data on 2,617 consecutive patients with STEMI treated with emergency PCI in 2005; in-hospital and 6-month outcomes of 99 patients who had experienced OHCA were compared with those of 2,518 patients without OHCA. The OHCA patients also underwent a cerebral performance evaluation after 12 months.

RESULTS

OHCA patients were at higher clinical risk at presentation (cardiogenic shock 26% vs 5%, P < .0001). Percutaneous coronary intervention was successful in 80% of the OHCA and 89% of the non-OHCA patients (P = NS). In-hospital mortality rates were 22% and 3%, respectively (P < .0001). Independent predictors of in-hospital mortality among OHCA patients were longer delay between the call to the emergency medical system and the start of cardiopulmonary resuscitation (odds ratio [OR] 3.5, P = .03), nonshockable initial rhythms (OR 10.5, P = .002), cardiogenic shock (OR 3.05, P = .035), and a Glasgow Coma Scale score of 3 on admission (OR 2.9, P = .032). The 6-month composite rate of death, myocardial infarction, and revascularization among OHCA patients surviving the acute phase was comparable to that of non-OHCA patients (16% vs 13.9%, P = NS), and 87% of them showed a favorable neurologic recovery after 1 year.

CONCLUSIONS

Resuscitated OHCA patients undergoing emergency PCI for STEMI have worse clinical presentation and higher in-hospital mortality compared to those without OHCA. However, subsequent cardiac events are similar, and neurologic recovery is more favorable than reported in most previous series.

Pig KALRN, MYH1, MLC2V, SNX13, AK1, and PPIA loci RH mapping and chromosome position refining

The suppressive subtractive hybridization technique was previously used by the authors to identify candidate genes for meat quality in pig. A set of ESTs homologous (>95%) to genes involved in muscle metabolism is reported in the present paper. Four ESTs homologous to MYH1, KALRN, MLC2V, and SNX13 genes plus two genes (AK1, PPIA) used as housekeeping for muscle tissue were assigned to porcine chromosomes using the INRA-Minnesota 7000 rads radiation hybrid panel (IMpRH). Our data confirm and refine the cytogenetic position of the KALRN, AK1, PPIA genes, improve the existing physical map of MYH1 and assign two new genes (MLC2V and SNX13) to swine chromosomes.

Stearoyl-Coenzyme A Desaturase Gene Polymorphism and Milk Fatty Acid Composition in Italian Holsteins

Milk fatty acid composition is a parameter of great interest for evaluation of nutritional quality of milk. Stearoyl-CoA desaturase (SCD) is a key enzyme in mammary lipid metabolism because it is able to add a double bond in the cis delta9-position in a large spectrum of medium- and long-chain fatty acids. A polymorphism with 2 alleles (A and V) in the fifth exon of the SCD gene has been reported. The effect of SCD genotype on individual milk fatty acid composition and on cis-9 unsaturated/saturated fatty acid ratios of 297 Holstein Italian Friesian cows was investigated in this paper. The SCD genotypes were determined by using a single strand conformation polymorphism method. Relative frequencies of SCD genotypes were 27, 60, and 13% for AA, AV, and VV, respectively. Milk of AA cows had a greater content of cis-9 C18:1 and total monounsaturated fatty acids and a higher C14:1/C14 ratio than did milk of VV cows. The relative contribution of SCD genotype to variation of monounsaturated fatty acids, cis-9 C18:1, and cis-9 C14:1 was 5, 4, and 7.7%, respectively. No significant differences were detected between SCD genotypes in the milk content of cis-9, trans-11 C18:2. Results of the present work provide some indication of an association between SCD locus and the fatty acid profile in the examined sample of Italian Holsteins, thus suggesting a possible role of this gene in the genetic variation of milk nutritional properties.

Detection of classical enterotoxins and identification of enterotoxin genes in Staphylococcus aureus from milk and dairy products

Milk and dairy products are frequently contaminated with enterotoxigenic Staphylococcus aureus, which is often involved in staphylococcal food poisoning. The distribution of genes encoding staphylococcal enterotoxins (SE) in S. aureus isolated from bovine, goat, sheep and buffalo milk and dairy products was verified by the presence of the corresponding SE production. A total of 112 strains of S. aureus were tested for SE production by immuno-enzymatic (SEA-SEE) and reversed passive latex agglutination (SEA-SED) methods, while multiplex-PCR was applied for SE genes (sea, sec, sed, seg, seh, sei, sej and sel). Of the total strains studied, 67% were detected to have some SE genes (se), but only 52% produced a detectable amount of the classic antigenic SE types. The bovine isolates frequently had enterotoxin SEA, SED and sej, while SEC and sel predominated in the goat and sheep strains. The results demonstrated (i) marked enterotoxigenic S. aureus strain variations, in accordance with strain origin and (ii) the two methods resulted in different information but concurred on the risk of foodstuff infection by S. aureus.

Molecular typing of Staphylococcus aureus isolated from cows, goats and sheep with intramammary infections on the basis of gene polymorphisms and toxins genes

We investigated 116 Staphylococcus aureus isolates from cows, goats and sheep with intramammary infections (IMI) in Italy to provide information about the spread of enterotoxigenic strains and to compare strains isolated from different ruminant species. The isolates were typed by restriction fragment length polymorphism (RFLP) analysis of the coagulase (coa) gene, by analysis of polymorphisms of the X region of protein A (spa) gene and by detection of genes encoding enterotoxins (sea, seb, sec, sed, see, seg, seh, sei, sej and sel). Seven different coa types and 12 different spa types were distinguished. On the basis of polymerase chain reaction-RFLP, 29 different coa subtypes were identified. Two different coa subtypes accounted for 49% and 67% of bovine and ovine isolates respectively. Only seven coa subtypes were observed in isolates from more than one host species and no coa subtype was present in isolates from all three ruminant species. Furthermore, 85 of the isolates (73%) harboured at least one enterotoxin gene (se) with a predominance of sea, sed and sej among isolates from bovine IMI, and sec and sel among isolates from caprine and ovine IMI. Comparing the S. aureus isolates on the basis of gene polymorphisms and presence of se genes, significant differences were found in distributions of genotypes among isolates from cows, goats and sheep.