Proof of concept for eradication of vancomycin resistant Enterococcus faecium from broiler farms

Background

Vancomycin resistant enterococci (VRE) in Swedish broiler production has been shown to persist at farms between batches. The aim of this study was therefore to determine the possibility to eliminate VRE by disinfection of compartments in broiler houses as a proof of concept.

Findings

VRE could not be detected in environmental samples from the disinfected test compartments in the broiler houses but was detected in environmental samples from the control compartments. The proportion of broilers colonized with VRE decreased in both the test and the control compartments.

Conclusions

The results are promising and show that the occurrence of VRE in broiler houses can be reduced by adequate cleaning and disinfection with a combination of steam and formaldehyde.     

High-level gentamicin-resistant and vancomycin-resistant Enterococcus faecium isolated from a wound in a dog

This report describes the first clinical case, in Europe, of a high-level gentamicin-resistant and vancomycin-resistant Enterococcus faecium infection in a dog. The aim of this report is to alert the veterinary profession to high-level gentamicin-resistant and vancomycin-resistant Enterococcus faecium in companion animal patients. Multi-drug resistant strains of this pathogen are the cause of considerable problems in human hospitals and for community healthcare professionals worldwide. The potential for a similar impact within veterinary medicine is discussed.     

Prevalence of vancomycin-resistant Enterococcus faecium (VREF) in pig faeces from slaughterhouses in Spain

A study to estimate the prevalence of vancomycin-resistant Enterococcus faecium in faecal samples from pigs at slaughterhouses in Spain was carried out between November 1998 and January 1999 with 900 samples taken from four abattoirs representing 9.7% of all pig slaughtered in 1998. Using a selective enrichment broth with vancomycin (8 μg/ml), 64 samples (7.1%; 95% CI: 5.5, 9.0%) had E. faecium vancomycin-resistant strains that showed minimal inhibitory concentrations of 256 μg/ml (62 strains) and 512 μg/ml (two strains). Results by farm showed that 43 of the 240 pig farms represented in the sampling had at least one faecal sample with vancomycin-resistant E. faecium.     

Methicillin resistant Staphylococcus aureus colonization in pigs and pig farmers

Methicillin resistant Staphylococcus aureus (MRSA) colonization has recently been identified in pigs and people that work with pigs, raising concerns about the role of pigs as reservoirs of MRSA for human infection. The objectives of this study were to evaluate the prevalence of MRSA colonization in pigs and pig farmers in Ontario, Canada and to characterize MRSA strains. Nasal and rectal swabs were collected from 285 pigs from three different age groups from 20 pig farms. Nasal swabs were collected from farm personnel and a brief questionnaire was also administered. The prevalence of MRSA colonization in farms was 45% (9/20) whereas the prevalence in pigs was 24.9% (71/285). There was no difference in MRSA colonization between age groups. The prevalence of MRSA colonization in pig farmers was 20% (5/25). There was a correlation between the presence of MRSA in pigs and humans on farms (P value=0.001). The results of spa typing revealed the predominant strain in pigs and humans was eGenomics spa type 539 (Ridom t034, clonal complex 398) which accounted for 59.2% of isolates and has been reported in pigs in Europe. A common human epidemic clone, CMRSA-2 (USA100, clonal complex 5) was also found in both pigs and pig personnel. Indistinguishable strains were found in pigs and pig personnel on all five farms with a colonized human. This study demonstrates that MRSA is common in pigs in Ontario, Canada, and provides further support to concerns about transmission of MRSA between pigs and humans.     

Horizontal transfer of vanA between probiotic Enterococcus faecium and Enterococcus faecalis in fermented soybean meal and in digestive tract of growing pigs

Background: The aim of this study was to investigate the intergeneric transfer of vancomycin resistance gene vanA between probiotic enterococci in the fermentation progress of soybean meal and in the digestive tract of growing pigs. One vanA genotype vancomycin resistant E. faecium strain, Efm4, and one chloramphenicol-resistant E. faecalis strain, Efs2, were isolated from twenty-nine probiotic basis feed material/additive samples. For in vitro conjugation,Efm4 and Efs2 were used as starter to ferment soybean meal. For in vivo conjugation, thirty growing pigs were randomly assigned to five groups(n = 6), treated with a basic diet, or supplemented with 10% fermented soybean meal, 1% Efm4, 5% Efs2 or a combination of 1% Efm4 + 5% Efs2 for 7 d, respectively. Fecal samples of pigs in each group were collected daily for the isolation and dynamic analysis of Efm4, Efs2 and transconjugants. The sequence types(STs) of Efm4, Efs2 and transconjugants were analyzed by multilocus sequence typing(MLST). The vanA harboring plasmid in Efm4 and transconjugants was analyzed by S1-pulsed field gel electrophoresis(PFGE)and further verified by multiple alignments.Results: The results showed that, in FSBM, transconjugants were detected 1 h after the fermentation, with a conjugation frequency of ～ 10-3 transconjugants/recipient. Transconjugants proliferated with Efm4 and Efs2 in the first 8 h and maintained steadily for 10 d till the end of the experiment. Additionally, in vivo experiment showed that transcojugants were recovered in one of six pigs in both FSBM and Efm4 + Efs2 groups, with conjugation frequency of ～ 10-5 and ～ 10-4, respectively. MLST revealed the ST of Efm4, Efs2 and transconjugants was ST1014, ST69 and ST69, respectively. S1-PFGE confirmed the existence of the vanA-harboring, 142,988-bp plasmid,which was also a multi-drug resistant plasmid containing Tn1546-like transposon.Conclusions: The findings revealed the potential safety hazard existing in the commercial probiotic enterococci in China, because the horizontal transfer from farm to fork could potentially pose a safety risk to the public.     

Lactic acid production and urease activity in strains of Enterococcus faecium found in the rumen and their genetic stability]

Lactic acid production, urease activity and genetic stability were investigated in five selected rumen strains of Enterococcus faecium. The average value of urease activity in the tested strains was 16.5 +/- 0.953 nkat per ml, two strains were urease-negative. The values of E. faecium strains produced lactic acid ranged from 1.087 +/- 0.134 to 1.787 +/- 0.213 mmol per 1 l. Cultivation of the strains in ethidium bromide (EB) eliminated urease activity of these strains already in the first subculture, but the elimination effects of sodium dodecyl sulphate (SDS) and acridine orange (AO) were manifested later on (1-8 subcultures). Lactic acid production was eliminated in all strains from 1st to 8th subculture after cultivation in SDS, EB and also AO.     

Susceptibility to vancomycin and other antibiotics of 165 Enterococcus strains isolated from dogs in Italy

The prevalence of antibiotic resistance, with special attention to vancomycin, in 165 Enterococcus strains isolated from dogs subjected or not to previous antibiotics treatment(s) was determined. For each strain, the minimum inhibitory concentration (MIC) to 9 antibiotics was assessed. All strains were sensible to vancomycin. High frequencies of resistance to erythromycin, tetracycline, rifampicin, and enrofloxacin were detected. E. faecium strains isolated from dogs subjected to antibiotic treatment were more resistant to tetracycline with respect to control dogs. Although enterococci from dog show a high degree of antibiotic resistance, they are sensitive to vancomycin. Therefore, the risk of transmission of vancomycin-resistant enterococcal strains from dogs to man is close to zero.     

猪源粪肠球菌耐药性及其Ⅰ类整合子遗传标记研究

为查明猪源粪肠球菌Ⅰ类整合子遗传标记及其相关耐药性,本研究对新疆某集约化猪场环境和粪便中分离的16株粪肠球菌进行磺胺类药物的敏感性测定和季胺类消毒液抑菌效果观察,同时以PCR法测定分离株中Ⅰ类整合子遗传标记,结果发现16株粪肠球菌中I类整合酶基因阳性率为75%(12/16),qacE△1-sul1基因阳性率为62.5%(10/16),对磺胺嘧啶的耐药率为81.25%(13/16),苯扎溴铵对分离株的抑菌率为31.25%(5/16)。表明分离株中I类整合酶基因和qacE△1-sul1基因携带率高;鉴于整合子对耐药基因水平传播的可能性,磺胺类药物作为预防猪场细菌性疾病的感染以及季胺类(苯扎溴铵)消毒剂作为猪场常规消毒剂需要科学的验证方可使用;同时警示应加强动物性食品源性细菌耐药性的监测,以阻断耐药基因给人的传播。     

中国地方猪种对世界养猪业的贡献、利用现状和展望

为了促进中国地方猪种产业的发展,本文从历史演化、利用现状与问题和具体对策等几个方面进行了系统的梳理。回顾了我国地方猪种的发展历史,简单阐述了目前国外的主要猪种是其祖先与我国地方猪种进行杂交之后所产生的这种遗传关系,同时,根据前人的数据文献总结了我国地方猪种的几个主要特征性状。另外,就目前我国地方猪种的发展中遇到的问题与现状提出了几点建议,以期为中国地方猪种进一步研究奠定基础。     

Susceptibility of Escherichia coli and Enterococcus faecium isolated from pigs and broiler chickens to tetracycline degradation products and distribution of tetracycline resistance determinants in E. coli from food animals

One hundred Escherichia coli isolates from diseased and healthy pigs, cattle and broiler chickens were screened for the presence of tetracycline resistance genes tet(A), (B), (C), (D) or (E). The tet(A) gene was the most abundant (71% of the 100 isolates) followed by tet(B) (25%). The predominance of tet(A) and tet(B) applied to all three animal species, and there was no difference between the distribution of tet(A) and tet(B) genes among non-pathogenic and pathogenic E. coli in any of the animal species. The susceptibility of 20 of these isolates together with 10 tetracycline sensitive E. coli and 18 tetracycline resistant and 10 sensitive Enterococcus faecium to tetracyclines and tetracycline degradation products was determined. The resistant isolates showed reduced resistance to anhydrotetracycline, 4-epi-anhydrotetracycline, anhydrochlortetracycline and 4-epi-anhydrochlortetracycline. In general both the tetracycline resistant and susceptible E. faecium were more susceptible to the compounds tested than E. coli.     

The possibility of positive selection for both F18(+)Escherichia coli and stress resistant pigs opens new perspectives for pig breeding

F18(+)Escherichia coli infections causing post-weaning diarrhoea and/or oedema disease are a major cause of economic losses in pig industry. To date, no preventive strategy can protect pigs from F18(+)E. coli infections. One of the most attractive approaches to eliminate F18(+)E. coli infections is the selection for pigs that are resistant to F18(+)E. coli infections. However, this strategy was not believed to be favourable because of reports of genetic association with the stress-susceptibility gene in the Swiss Landrace. To investigate this potential association more thoroughly, 131 randomly selected Belgian hybrid pigs were genotyped for both the F18(+)E. coli resistance alleles (FUT1(A)) and the stress-susceptibility alleles (RYR1(T)) and their association was investigated by determining the linkage disequilibrium. This linkage disequilibrium (LD=-0.0149) is close to zero and does not differ significantly from 0 (likelihood ratio test chi(1)(2)=1.123, P=0.29), demonstrating no association between the FUT1(A) and RYR1(T) alleles. Furthermore, only a small fraction (4.6%) of the Belgian pigs was found to be resistant to F18(+)E. coli infections. Our results suggest that selection for F18(+)E. coli resistant pigs might be an attractive approach to prevent pigs from F18(+)E. coli infections, unlike to what has previously been postulated.     

Effects of a probiotic Enterococcus faecium strain supplemented from birth to weaning on diarrhoea patterns and performance of piglets

This placebo-controlled double-blind study was conducted to evaluate effects of Enterococcus faecium DSM 10663 NCIMB 10415 (EcF) orally given from birth to weaning on diarrhoea and performance of piglets. At the first 3 days postnatum (p.n.), piglets from 54 [verum group (VG)] and 60 [placebo group (PG)] sows got 1 g of a gel directly per mouth by a dosing device. Gel for the VG contained 2.8 x 10(9) colony forming units (CFU) EcF/g. From day 4 p.n. until weaning (24 +/- 3.2 days p.n.) a liquid additive was given that administered twice a day 1.26 x 10(9) CFU EcF to each VG piglet. In case of diarrhoea, an electrolyte solution was used which provided daily 2.9 and 5.8 (week 1 and >or= 2, respectively) x 10(8) CFU EcF per VG piglet. Diarrhoea scores were defined as follows: (i) no diarrhoea; (ii) piglets developed diarrhoea, but were vital and (iii) piglets suffered from diarrhoea and additionally looked pale, developed rough coat, showed slackening of the flank and lethargy. Counts of viable born, stillborn and weaned piglets were normal and not different between groups (p > 0.05). Placebo group vs. VG piglets suffered more frequently from diarrhoea (40.0 vs. 14.8%, p < 0.05). Duration of diarrhoea was not affected by feeding EcF (2.2 +/- 0.81 days, p > 0.05). Diarrhoea score was lower in VG vs. PG (1.2 vs. 1.5 +/- 0.54, p < 0.05) and the daily weight gain (DWG) was higher by 17 g/day (p < 0.05). Results suggest that the daily oral supplementation of EcF from birth to weaning reduces the portion of piglets suffering from diarrhoea. This may improve performance, as the higher DWG indicates. In contrast, no obvious benefit seems to result from an additional supply of EcF via electrolyte solution when diarrhoea is always present.     

Isolation and Molecular Characterization of Vancomycin‐Resistant Enterococcus faecium from Swine in Michigan,USA

In 2008, we identified vancomycin‐resistant enterococci (VRE) in Michigan swine, which was the first report of VRE in livestock from North America. Continued sampling in 2009 and 2010 was conducted to determine whether VRE persisted in Michigan. In 2009, swine faecal and feed samples (n = 56), county fair pig barn manure samples (n = 9) and pooled Michigan State Fair pig barn manure samples (n = 18) were screened for VRE. In 2010, swine faecal samples were collected from 26 county fairs (n = 73) and nine commercial swine farms in six states (n = 28). Recovered VRE isolates were molecularly evaluated by polymerase chain reaction, restriction fragment length polymorphism, pulsed‐field gel electrophoresis (PFGE), S1 nuclease digestion and multilocus sequence typing (MLST). Six VRE isolates were identified in 2009 from the State Fair, and another six (8.2%) were recovered from the five county fairs in 2010. All 12 isolates were highly related to the first‐reported VRE from Michigan swine: all were confirmed to be vancomycin‐resistant Enterococcus faecium (VREf) carrying vanA gene on Tn1546 (Type D), were negative for IS1251, hyl and esp gene, carried a 150–160 kb megaplasmid, and have closely similar PFGE patterns with >80% similarity. Classified as ST5, ST6 or ST185 by MLST, all belong to the clonal complex 5, a strain recognized to be circulating among European pigs. This study reveals that VREf are widespread in Michigan swine and persist in the historical absence of the use of agricultural glycopeptides.     

Use of avilamycin for growth promotion and avilamycin-resistance among Enterococcus faecium from broilers in a matched case-control study in France

We assessed the putative link between avilamycin-resistant Enterococcus faecium carriage and avilamycin consumption in broilers. As part of the French programme of monitoring for antimicrobial resistance, broilers sampled at slaughterhouse in 1999 and 2000 and carrying avilamycin-resistant E. faecium were matched by slaughterhouse, slaughter month and production type (free-range, standard, light) with control broilers carrying avilamycin-susceptible strains. History of antibiotics consumption (either for growth promotion or therapeutic purpose) in the broiler flocks sampled was collected from the monitoring programme and consumption of each antibiotic class was screened as a potential risk factor. Avilamycin was a risk factor for avilamycin-resistant E. faecium carriage: OR = 2.3.     

Establishing the change in antibiotic resistance of Enterococcus faecium strains isolated from Dutch broilers by logistic regression and survival analysis

In this study, we investigated the change in the resistance of Enterococcus faecium strains isolated from Dutch broilers against erythromycin and virginiamycin in 1998, 1999 and 2001 by logistic regression analysis and survival analysis. The E. faecium strains were isolated from caecal samples that had been randomly collected from six slaughterhouses. Moreover, between the sample collection in 1998 and the sample collection in 1999, virginiamycin and the macrolide antibiotics (of which erythromycin is a member) have been banned in The Netherlands from use in broiler feeds as growth promoter. In the logistic regression analysis we used the internationally accepted cut-off values to determine whether bacteria were resistant or not. In the survival analysis, inhibition of bacterial growth was the event and time to event was replaced by concentration of antibiotic to event. As a consequence, changes in the growth of bacteria can be tested over an entire range of concentrations and no cut-off value for resistance has to be determined. We performed the survival analysis by use of a Cox logistic model with an odds ratio (OR) for the increase of the odds of the basic hazard rate as outcome. Both the logistic regression and the survival analyses showed that resistance to erythromycin and virginiamycin decreased during the study period. In the logistic regression model the ORs associated with the fraction of bacteria inhibited by the antibiotics in 2001 as compared to 1998 were 3.76 (2.57-5.49) for erythromycin and 11.65 (7.68-17.66) for virginiamycin. The corresponding ORs from the survival analysis were lower; 2.88 (2.21-3.76) and 2.11 (1.80-2.49), respectively. The reason for the differences between the ORs of the survival analysis and the logistic regression analysis is probably because most changes in resistance included the cut-off value and logistic regression specifically examines those changes.     

Occurrence of MRSA in pigs and in humans involved in pig production--preliminary results of a study in the northwest of Germany

In 2007, 678 pigs of all age groups out of 347 different farms from Lower Saxony and Northrhine-Westphalia and 86 persons occupationally exposed to pigs were investigated for their nasal colonisation with methicillin-resistant Staphylococcus areus (MRSA) by the Field Station for Epidemiology of the University of Veterinary Medicine Hannover and the Robert Koch-Institute. At the individual animal level, a frequency of positive results of 13% (n = 85 positive animals) and at the herd level, a frequency of positive results of 18% (n = 62 positive herds) were found. All isolates were assigned to the Multilocus Sequence Typing Type ST398. Within MRSA-positive herds, there were more MRSA-negative than MRSA-positive animals. Among the occupationally exposed persons (veterinarians, laboratory personnel and meat inspection personnel), 20 persons (23%) showed a nasal colonisation with MRSA ST398. A quite strong association between the intensity of the contact to pigs with the frequency of nasal colonisation in the occupationally exposed persons was detected. None of the animals or the humans nasally colonised by MRSA ST398 showed any clinical symptoms of a staphylococcal infection. Conclusions are drawn on the herd and intra-herd prevalence of the nasal colonisation of pigs with MRSA ST398 in pigs, but especially on which questions need to be addressed by further research.