Hilde Moyaert

Antimicrobial susceptibility monitoring of respiratory tract pathogens isolated from diseased cattle and pigs across Europe: the VetPath study.

VetPath is an ongoing pan-European antibiotic susceptibility monitoring programme collecting pathogens from diseased antimicrobial non-treated cattle, pigs and poultry. In the current study, 1001 isolates from cattle and pig respiratory tract infections were tested for their antimicrobial susceptibilities. Non-replicate lung samples or nasopharyngeal/nasal swabs were collected from animals with acute clinical signs in 11 countries during 2002-2006. Pasteurella multocida and Mannheimia haemolytica from cattle and P. multocida, Actinobacillus pleuropneumoniae and Streptococcus suis from pigs were isolated by standard methods. S. suis was also isolated from meningitis cases. MICs of 16 antibiotics were assessed centrally by broth microdilution following CLSI recommendations. Results were interpreted using CLSI breakpoints where available. P. multocida (231) and M. haemolytica (138) isolates were all susceptible to amoxicillin/clavulanic acid, ceftiofur, enrofloxacin and trimethoprim/sulfamethoxazole. Resistance to florfenicol and spectinomycin was 0.4% and 3.5% in P. multocida, respectively, and absent in M. haemolytica isolates. Tetracycline resistance was 5.7% and 14.6% for P. multocida and M. haemolytica. In pigs, 230 P. multocida, 220 A. pleuropneumoniae and 182 S. suis isolates were recovered. Resistance to amoxicillin/clavulanic acid, ceftiofur, enrofloxacin, florfenicol, tiamulin and tilmicosin was absent or <1%. Trimethoprim/sulfamethoxazole resistance was 3-6% and tetracycline resistance varied from 14.7% in A. pleuropneumoniae to 81.8% in S. suis. In conclusion, low resistance to antibiotics with defined clinical breakpoints, except for tetracycline, was observed among the major respiratory tract pathogens recovered from cattle and pigs. Since for approximately half of the antibiotics in this panel no CLSI-defined breakpoints were available, setting of the missing veterinary breakpoints is important.

Evaluation of 16S rRNA Gene-Based PCR Assays for Genus-Level Identification of Helicobacter Species

ABSTRACT The inclusivity, exclusivity, and detection limit of six 16S rRNA gene-based Helicobacter genus-specific PCR assays were examined. Five out of six assays were 100% inclusive, but the tests varied considerably in their exclusivity (9.1 to 95.5%). The clinical detection limit varied between 103 and 1 viable bacterial cell per reaction mixture.

Monitoring of antimicrobial susceptibility of respiratory tract pathogens isolated from diseased cattle and pigs across Europe, 2009–2012: VetPath results

VetPath is an ongoing pan-European antibiotic susceptibility monitoring programme that collects pathogens from diseased cattle, pigs and poultry. In the current study, 996 isolates from cattle and pig respiratory tract infections were tested for their antimicrobial susceptibilities. Non-replicate lung samples or nasopharyngeal/nasal swabs were collected from animals with acute clinical signs in 10 countries during 2009-2012. Pasteurella multocida, Mannheimia haemolytica and Histophilus somni from cattle and P. multocida, Actinobacillus pleuropneumoniae, Haemophilus parasuis, Bordetella bronchiseptica and Streptococcus suis from pigs were isolated by standard methods. S. suis was also isolated from meningitis cases. MIC values of 16 or 17 antibiotics were assessed centrally by broth microdilution following CLSI standards. Results were interpreted using CLSI breakpoints where available. Cattle isolates were generally highly susceptible to most antibiotics, except to tetracycline (3.0-12.0% resistance). Low levels of resistance (0-4.0%) were observed for the macrolide antibiotics. Resistance to spectinomycin varied from 0 to 6.0%. In pig isolates similar observations were made. Resistance to amoxicillin/clavulanic acid, ceftiofur, enrofloxacin, florfenicol, tulathromycin, tiamulin and tilmicosin was absent or <2%. Trimethoprim/sulfamethoxazole resistance varied from 1.9 to 5.3%, but tetracycline resistance varied from 20.4% in P. multocida to 88.1% in S. suis. For most antibiotics and pathogens the percentage resistance remained unchanged or only increased numerically as compared to that of the period 2002-2006. In conclusion, absence or low resistance to antibiotics with defined clinical breakpoints, except for tetracycline, was observed among the major respiratory tract pathogens recovered from livestock. Comparison of all antibiotics and organisms was hampered since for almost half of the antibiotics no CLSI-defined breakpoints were available.

Antimicrobial susceptibility monitoring of mastitis pathogens isolated from acute cases of clinical mastitis in dairy cows across Europe: VetPath results

VetPath is an ongoing pan-European antimicrobial susceptibility monitoring programme collecting pathogens from diseased cattle, pigs and poultry not recently treated with antibiotics. Non-replicate milk samples were collected from cows with acute clinical mastitis in eight countries. Escherichia coli, Staphylococcus aureus and Streptococcus uberis were isolated by standardised methods. Antimicrobial susceptibility was determined in a central laboratory by CLSI broth microdilution methodology; results were interpreted using clinical breakpoints where available. Among E. coli (n=280), resistance to tetracycline (14.3%) and cefapirin (11.1%) were most common. Resistance to other β-lactam antibiotics was absent (ceftiofur) or very low (cefalexin, amoxicillin/clavulanic acid). The MIC90 of enrofloxacin and marbofloxacin was 0.03 and 0.06μg/mL, respectively, with 0.7% of strains displaying a deviating high MIC. Staphylococcus aureus (n=250) were susceptible to most antibiotics tested, although 36.0% were resistant to penicillin G. For other β-lactam antibiotics where a CLSI breakpoint was available, no resistance was detected. Tetracycline resistance was low (5.2%). Streptococcus uberis (n=282) were susceptible to all β-lactam antibiotics, although 29.8% were intermediately susceptible to penicillin G; 18.8% of strains were resistant to erythromycin and 28.7% to tetracycline. This European study shows that bacteria associated with acute clinical mastitis are susceptible to most antibiotics with the exception of penicillin G against S. aureus, and erythromycin and tetracycline against S. uberis. The results of this study should serve as a reference baseline. This work also highlights the urgent need to set additional clinical breakpoints for antibiotics frequently used to treat mastitis.

Helicobacter equorum is highly prevalent in foals

Faecal samples of sixty-six 3-day- to 6-month-old foals were screened for Helicobacter equorum DNA by means of a PCR amplifying a 1074 bp fragment of the 23S rRNA gene with primers specific for this enterohepatic Helicobacter species. H. equorum DNA was demonstrated in faeces from 28.6% of the less than 1-month-old foals, while 67.8% of foals from 1 to 6 months of age tested positive. In a previous study, H. equorum was demonstrated in faeces of 0.8-7.9% of adult horses. These results indicate that the prevalence of H. equorum in horses differs with the age of the investigated horse population. The organism seems highly prevalent in foals between 1 and 6 months of age but the possible association with intestinal disease in this age group needs further investigation.

Extragastric Manifestations ofHelicobacter pyloriInfection: OtherHelicobacters

The finding that Helicobacter pylori is the main cause of gastritis and peptic ulcer disease has opened a new era in the gastrointestinal world. Today there is evidence that H. pylori may also play a role in different nongastric diseases, opening the new “extragastric manifestations of H. pylori infection” field. Concerning this, several studies have been published in the last year. The most convincing data arise from those investigating idiopathic thrombocytopenic purpura and sideropenic anemia, while there is also an increasing evidence for a possible association with atherosclerotic disease. Furthermore, the discovery of a number of other novel Helicobacter species has stimulated the research in different extragastric diseases, in which an infectious hypothesis is plausible. In particular, several species have been studied for a potential role in different liver and intestinal diseases with interesting findings.

Acute in vivo interactions of Helicobacter equorum with its equine host

REASONS FOR PERFORMING STUDY A novel urease-negative Helicobacter species has been isolated from faecal samples of clinically healthy horses, but no information is available about the main sites of colonisation in the equine gastrointestinal tract nor is the pathogenic potential of this microorganism known. An experimental infection in horses was therefore carried out. METHODS Four horses were infected with H. equorum strain CCUG 52199T and subjected to euthanasia at 10 (n = 2) and 30 days (n = 2) post inoculation. A fifth animal was inoculated with phosphate buffered saline and used as control. Gastrointestinal samples were examined histologically and bacteriologically. These samples, as well as faecal material collected at regular intervals, were also subjected to PCR analysis. RESULTS All horses remained clinically healthy and no specific macroscopic lesions were identified, nor were there any microscopic changes. H. equorum-DNA was detected in the faeces during the whole experiment in all infected animals but not in the negative control. Sites of colonisation were caecum, colon and rectum. CONCLUSIONS H. equorum is able to colonise the equine lower bowel and is excreted in faeces without apparent pathology. No association between the presence of the organism and gastrointestinal disease was demonstrated.

Antimicrobial susceptibility monitoring of dermatological bacterial pathogens isolated from diseased dogs and cats across Europe (ComPath results)

The ComPath project is a pan‐European programme dedicated to the monitoring of antimicrobial susceptibility of pathogens from diseased dogs and cats using standardized methods and centralized minimum inhibitory concentration (MIC) determination. Here, the susceptibility of major pathogens is reported from antimicrobial nontreated animals with acute clinical signs of skin, wound or ear infections in 2008–2010.

Helicobacter equorum: prevalence and significance for horses and humans.

Helicobacter equorum colonizes the caecum, colon and rectum of horses. The agent is highly prevalent in <6-month-old foals. In adult horses, the prevalence of H. equorum seems to be rather low, but these animals may harbour low, subdetectable numbers of this microorganism in their intestines. So far, no association could be made between the presence of H. equorum and clinical disease or intestinal lesions in adult horses. Further research is necessary to elucidate the pathogenic potential of this bacterial species towards young foals. Helicobacter equorum DNA was not detected in human faeces, indicating that this microorganism does not commonly spread from horses towards humans.

Antimicrobial susceptibility monitoring of bacterial pathogens isolated from respiratory tract infections in dogs and cats across Europe: ComPath results

ComPath is a pan-European resistance monitoring programme collecting bacterial pathogens from dogs and cats. We present data for respiratory tract infection (RTI) isolates collected between 2008 and 2010. Antimicrobial minimal inhibitory concentrations (MICs) were determined and susceptibility calculated following Clinical Laboratory Standards Institute (CLSI) standards for veterinary medicine. The main pathogen from dogs was Staphylococcus intermedius Group (49/215, 22.8%) which was >90% susceptible to most antimicrobials (including oxacillin - 93.9%; 3 isolates confirmed mecA-positive) but only 59.2%, 73.5% and 87.8% susceptible to tetracycline, chloramphenicol and penicillin. Bordetella bronchiseptica (48/215, 22.3%), streptococci (36/215, 16.7%), Escherichia coli (24/215, 11.2%) and Pasteurella multocida (23/215, 10.7%) were also found in dog RTI. There are no breakpoints for Bordetella bronchiseptica. Most streptococci were penicillin- chloramphenicol-, ampicillin- and pradofloxacin-susceptible. None were enrofloxacin-resistant but 6 isolates (16.7%) were of intermediate susceptibility. The least active agent against streptococci was tetracycline (47.2% susceptible). For E. coli, 37.5% were ampicillin-susceptible but 83.3% were amoxicillin/clavulanic acid-susceptible. Only chloramphenicol showed susceptibility>90% against E. coli, with 66.7% tetracycline-susceptible and 79.2% to 87.5% susceptibility to enrofloxacin, trimethoprim-sulfamethoxazole or pradofloxacin. P. multocida were susceptible to pradofloxacin (no other breakpoints are available). The main pathogen from cats was P. multocida (82/186, 44.1%), where only pradofloxacin has breakpoints (100% susceptible). Streptococci were also collected from cats (25/186, 13.4%) and were >90% susceptible to all antimicrobials except tetracycline (36% susceptible). Most susceptibility was calculated with human-derived breakpoints and some antimicrobials had no breakpoints. Therefore predictions of clinical utility for dog and cat RTI will remain problematical unless specific breakpoints are set.