Low levels of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand

Abstract

AIM: To provide baseline data on the levels and patterns of antibacterial drug resistance expressed by Gram-negative bacteria isolated from poultry carcasses in New Zealand.

METHODS: Between July and December 2006, isolates of Escherichia coli (n=407) and Salmonella spp. (n=3) originating from carcass-rinse samples were submitted by testing laboratories affiliated to five major poultry processing plants. Isolates of Campylobacter jejuni (n=193) originating from retail poultry carcasses in 2005–2006 were retrieved from the Massey University archives. All isolates underwent disc diffusion susceptibility testing against panels of 12 (Enterobacteriaceae) and six (Campylobacter spp.) antibacterial drugs. Cephalothin-resistance in isolates of E. coli was confirmed using ETest strips, and confirmation of the resistance phenotypes for a subset of C. jejuni isolates used microbroth dilution assays. Patterns within the resistance phenotypes of the isolates were investigated using hierarchical clustering, and logistic regression modelling.

RESULTS: The majority of isolates (71.5% E. coli, 99% C. jejuni, and all three Salmonella spp. isolates) were fully susceptible to the drugs that were tested. Four (1%) E. coli isolates showed resistance to three or more drugs. The proportions of susceptible E. coli differed between the five processing plants. Resistances were detected in E. coli isolates, using disc diffusion to cephalothin (18.2%), ampicillin (4.4%), tetracycline (4.4%) and gentamicin (1.5%). There was an association between cephalothin-resistant isolates of E. coli and decreased susceptibility to gentamicin. Using ETests to ascertain the minimum inhibitory concentrations (MIC) of E. coli for cephalothin gave inconsistent results. One of 193 C. jejuni isolates was resistant to erythromycin, and microbroth dilution assays confirmed that this panel of C. jejuni was generally susceptible to antibacterial drugs.

CONCLUSIONS: The levels of resistance shown by Gram-negative bacteria isolated from chicken carcasses in New Zealand are among the lowest reported around the world. No resistance to extended-spectrum cephalosporin drugs was detected in E. coli, suggesting that CTX-M and AmpC beta-lactamases are rare or absent. Salmonella spp. are rarely isolated from poultry carcasses during routine testing in New Zealand, and the isolates identified during this study were fully susceptible to the drugs tested. A panel of C. jejuni isolates originating from retail poultry carcasses were susceptible to first-line and second-line antibacterial drugs. The use of cephalothin as a marker of resistance to first-generation cephalosporins may not be appropriate for non-type-specific E. coli of animal origin.     

Circadian polymorphisms associated with affective disorders

Background  

Clinical symptoms of affective disorders, their response to light treatment, and sensitivity to other circadian interventions indicate that the circadian system has a role in mood disorders. Possibly the mechanisms involve circadian seasonal and photoperiodic mechanisms. Since genetic susceptibilities contribute a strong component to affective disorders, we explored whether circadian gene polymorphisms were associated with affective disorders in four complementary studies.     

Sum rules and interlayer conductivity of high-Tc cuprates

Analysis of the interlayer infrared conductivity of cuprate high-transition temperature superconductors reveals an anomalously large energy scale extending up to midinfrared frequencies that can be attributed to formation of the superconducting condensate. This unusual effect is observed in a va- riety of materials, including Tl2Ba2CuO6+x, La2-xSrxCuO4, and YBa2Cu3O6.6, which show an incoherent interlayer response in the normal state. Midinfrared range condensation was examined in the context of sum rules that can be formulated for the complex conductivity. One possible interpretation of these experiments is in terms of a kinetic energy change associated with the superconducting transition.     

Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

Splenic lymphoma in a short-beaked echidna (Tachyglossus aculeatus)

A 23-year-old, male short-beaked echidna ( Tachyglossus aculeatus ) housed at a North American zoo was successfully treated for flea-associated anaemia, but subsequently died. Cause of death was presumptive septicaemia secondary to splenic lymphoma. This is only the fifth case of neoplasia reported in this monotreme species, and the first from outside of Australia.     

Lectin‐Binding Pattern in Ovarian Structures of Rats with Experimental Polycystic Ovaries

Numerous experimental models in different species have been developed for the study of polycystic ovarian syndrome. In this study, we used a model of induction of polycystic ovaries (PO) in rats by exposure to constant light to study the distribution and variations of glycosylated residues present in the different ovarian structures. Seven biotinylated lectins were used (Con‐A, WGA, DBA, SBA, PNA, RCA and UEA‐I) on tissue sections, and detection was performed using the streptavidin/peroxidase method. In tissue sections was observed an increase in affinity for Con‐A in the granulosa and theca interna of growing follicles and cysts in animals with PO in relation to the control group. Follicular cysts showed higher affinity for WGA and RCA‐I which growing follicles in the same group, and there was a decrease in affinity for PNA in the cysts in relation to the growth of follicles in both groups. Atretic follicles in both groups showed greater labelling with lectins PNA, SBA and RCA‐I in relation to healthy follicles. It could also be noted that the zona pellucida of cystic follicles lost the affinity for the lectin Con‐A. There was no staining on follicles in any category with the lectins DBA and UEA‐I, although it was staining in the corpus luteum (control group) and in the mesothelium and interstitial glands of both groups with DBA. These observations probably reflect changes in the glycosaminoglycans present in the different ovarian compartments or in the glycosylation of cellular components essential for proper follicular dynamics.     

Liquorice and canine Addison's disease

Abstract

Extract

Hypoadrenocorticism, or Addison's disease, is an uncommon en-docrinopathy of dogs (Feldman and Nelson 2004 Feldman, EC and Nelson, RW. 2004. “Hypoadrenocorticism (Addison's disease)”. In Canine and Feline Endocrinology and Reproduction, 3rd, 394–439. Philadelphia, , USA: WB Saunders.  [Google Scholar]). Long-term management of affected dogs in New Zealand involves treatment with oral fludrocortisone acetate (Florinef tablets; Bristol-Myers Squibb (NZ) Ltd, Auckland, NZ), which is a relatively expensive synthetic adrenocortical steroid. Table salt may be added to the food, in an attempt to reduce the amount of fludrocortisone required. Despite fludrocortisone therapy, many Addisonian dogs remain hyponatraemic and hyperkalaemic and the required dose of fludrocortisone may need to be increased during the first year of treatment. Increasing the dose of fludrocortisone is not only expensive, but may also have undesirable effects through its potent glucocorticoid action.     

Mycobacterium avium subsp. paratuberculosis infection in wildlife on three deer farms with a history of Johne's disease

Abstract

AIM: To determine the prevalence of Mycobacterium avium subsp. paratuberculosis (Map) infection in wildlife, in pastoral landscapes with a recent history of clinical Johne's disease in livestock.

METHODS: A total of 449 wild mammals and birds from three farms in the South Island of New Zealand with recent histories of clinical Johne's disease in their deer herds were trapped and examined for gross pathological changes in the gastrointestinal tract. Additionally, individual mesenteric lymph nodes from 380 mammals, and segments of gastrointestinal tract from 32 birds were excised, homogenised and cultured for viable Map bacilli. The prevalence of Map infection was then calculated for the various species. Faecal samples from those mammals which had culture-positive tissues were further cultured for the presence of Map.

RESULTS: Gross pathological changes were identified in the gastrointestinal tract of four brushtail possums, one cat, six ferrets, 12 hares, six hedgehogs, three rabbits, one stoat, and one paradise shelduck. Infection with Map in the gastrointestinal tract was confirmed in only three of these cases, one each of brushtail possums, hares and hedgehogs. In contrast, Map infection in the absence of gross pathological changes was frequently recorded in enteric tract tissues of mammals and birds. Among mammals, Map infection was recorded in 18/73 (25%) brushtail possums, 4/23 (17%) cats, 15/42 (36%) hedgehogs and 29/113 (26%) rabbits. Among birds, intestinal tract tissue Map infection was recorded in 3/17 (18%) paradise shelducks. Among 64 of the 74 mammals which had Map culture-positive tissues, 38% (n=5) of hedgehogs and 11% (n=3) of rabbits also had culture-positive faecal samples.

CONCLUSIONS: This study is the first to identify that Map infection can be prevalent in wildlife in New Zealand. There was a high prevalence of Map infection among both scavenging and grazing wild animals. Both mammals and birds are capable of harbouring viable Map organisms in their gastrointestinal tract; further, viable Map was excreted into the environment via faeces by hedgehogs and rabbits.

CLINICAL RELEVANCE: Previous studies overseas have postulated a role of wildlife as reservoirs of Map infection and possible vectors of Johne's disease to livestock. Here, brushtail possums, hedgehogs and rabbits and in particular were identified as potential wildlife hosts for Map infection in NewZealand. This suggests that several wildlife species could contribute to the persistence of Map infection within a wildlife/livestock complex, and potentially, perhaps more importantly, to the spread of infection between farms.