Why is anti-microbial resistance a veterinary problem as well?

Health risk assessment of antimicrobial residues in sheep carcasses marketed in Kuwait

A total of 450 samples comprising 150 each of muscles, livers and kidneys were collected from 150 sheep carcasses in Kuwait and tested by both Rapid Premi®Test kits for rapid detection of antimicrobial-positive samples, and the High-performance liquid chromatography (HPLC) for residual determination of amoxicillin, tetracycline, oxytetracycline, and tylosin. Premi test revealed that 82%, 64% and 100% of the muscle, liver and kidney samples examined, respectively were positive for antimicrobials. HPLC analysis revealed mean concentrations (µg/kg) of 45.26, 148.17, 103.18, and 71.80 for amoxicillin, oxytetracycline, tetracycline, and tylosin respectively in muscles; 64.43, 263.15, 177.04, and 112.94, respectively in livers; and 53.12, 368.21, 196.40, and 138.63, respectively in kidneys. Although many samples exceeded the maximum residue limit (MRL) of Codex Alimentarius, the assessment of dietary exposure to the antimicrobials tested through consumption of sheep meat and organs did not constitute any health hazards in the different age groups of Kuwaiti population.

A 10-day vacancy period after cleaning and disinfection has no effect on the bacterial load in pig nursery units

BACKGROUND

Biosecurity measures such as cleaning, disinfection and a vacancy period between production cycles on pig farms are essential to prevent disease outbreaks. No studies have tested the effect of a longer vacancy period on bacterial load in nursery units.

METHODS

The present study evaluated the effect of a 10-day vacancy period in pig nursery units on total aerobic flora, Enterococcus spp., Escherichia coli, faecal coliforms and methicillin resistant Staphylococcus aureus (MRSA). Three vacancy periods of 10 days were monitored, each time applied in 3 units. The microbiological load was measured before disinfection and at 1, 4, 7 and 10 days after disinfection.

RESULTS

No significant decrease or increase in E. coli, faecal coliforms, MRSA and Enterococcus spp. was noticed. Total aerobic flora counts were the lowest on day 4 after disinfection (i.e. 4.07 log CFU/625 cm2) (P < 0.05), but the difference with other sampling moments was limited (i.e. 0.6 log CFU/625 cm2) and therefore negligible. Furthermore, this observation on day 4 was not confirmed for the other microbiological parameters. After disinfection, drinking nipples were still mostly contaminated with total aerobic flora (i.e. 5.32 log CFU/625 cm2) and Enterococcus spp. (i.e. 95 % of the samples were positive) (P < 0.01); the feeding troughs were the cleanest location (total aerobic flora: 3.53 log CFU/625 cm2 and Enterococcus spp.: 50 % positive samples) (P < 0.01).

CONCLUSIONS

This study indicates that prolonging the vacancy period in nursery units to 10 days after disinfection with no extra biosecurity measures has no impact on the environmental load of total aerobic flora, E. coli, faecal coliforms, MRSA and Enterococcus spp..

Comparison of competitive exclusion with classical cleaning and disinfection on bacterial load in pig nursery units

Background

Colonisation of the environment of nursery units by pathogenic micro-organisms is an important factor in the persistence and spread of endemic diseases in pigs and zoonotic pathogens. These pathogens are generally controlled by the use of antibiotics and disinfectants. Since an increasing resistance against these measures has been reported in recent years, methods such as competitive exclusion (CE) are promoted as promising alternatives.

Results

This study showed that the infection pressure in CE units after microbial cleaning was not reduced to the same degree as in control units. Despite sufficient administration of probiotic-type spores, the analysed bacteria did not decrease in number after 3 production rounds in CE units, indicating no competitive exclusion. In addition, no differences in feed conversion were found between piglets raised in CE and control units in our study. Also, no differences in faecal consistency (indicator for enteric diseases) was noticed.

Conclusion

These results indicate that the CE protocol is not a valuable alternative for classical C&D.

Bactérias envolvidas nas mastites subclínicas de cabra da região de Salvador, Bahia

A mastite é uma infecção frequente da glândula mamária, sendo a principal doença que afeta o úbere das fêmeas e responsável pelos maiores prejuízos à produção leiteira em caprinos, reduzindo em quantidade e depreciando a qualidade do leite e seus derivados. Nesse estudo foram colhidas amostras de leite de cabras com reação positiva ao CMT, em propriedades localizadas em Bonfim de Feira, Barra do Pojuca, Feira de Santana, Camaçari, Anguera e Antônio Cardoso, todas próximas à Cidade de Salvador, Bahia. Do material coletado foi realizado cultivo bacteriológico em ágar sangue de ovino a 10%, ágar McConkey e também enriquecido em caldo BHI. O Staphylococcus spp. foi a bactéria de maior prevalência (90,3%), seguida de Streptococcus (4,8%), Micrococcus (1,6%) e Enterobacter (1,6%). Todas as bactérias foram submetidas ao teste de sensibilidade aos antimicrobianos pelo método de difusão em disco, sendo que 54,1% das estirpes estudadas apresentaram sensibilidade a todas as drogas testadas, e 45,9% das estirpes identificadas apresentaram resistência a pelo menos um dos antimicrobianos. O presente estudo confirmou o Staphylococcus spp. como a principal bactéria envolvida na etiologia das mastites subclínicas caprinas.

Calf health from birth to weaning. III. housing and management of calf pneumonia

Calfhood diseases have a major impact on the economic viability of cattle operations. A three part review series has been developed focusing on calf health from birth to weaning. In this paper, the last of the three part series, we review disease prevention and management with particular reference to pneumonia, focusing primarily on the pre-weaned calf. Pneumonia in recently weaned suckler calves is also considered, where the key risk factors are related to the time of weaning. Weaning of the suckler calf is often combined with additional stressors including a change in nutrition, environmental change, transport and painful husbandry procedures (castration, dehorning). The reduction of the cumulative effects of these multiple stressors around the time of weaning together with vaccination programmes (preconditioning) can reduce subsequent morbidity and mortality in the feedlot. In most studies, calves housed individually and calves housed outdoors with shelter, are associated with decreased risk of disease. Even though it poses greater management challenges, successful group housing of calves is possible. Special emphasis should be given to equal age groups and to keeping groups stable once they are formed. The management of pneumonia in calves is reliant on a sound understanding of aetiology, relevant risk factors, and of effective approaches to diagnosis and treatment. Early signs of pneumonia include increased respiratory rate and fever, followed by depression. The single most important factor determining the success of therapy in calves with pneumonia is early onset of treatment, and subsequent adequate duration of treatment. The efficacy and economical viability of vaccination against respiratory disease in calves remains unclear.

Calf health from birth to weaning. II. Management of diarrhoea in pre-weaned calves

Calfhood diseases have a major impact on the economic viability of cattle operations. The second of this three part review series considers the management of diarrhoeic diseases in pre-weaned calves. In neonatal calf diarrhoea, oral rehydration therapy is the single most important therapeutic measure to be carried out by the farmer and is usually successful if instigated immediately after diarrhoea has developed. Continued feeding of milk or milk replacer to diarrhoeic calves is important, to prevent malnourishment and weight loss in affected calves. Indiscriminative antibiotic treatment of uncomplicated diarrhoea is discouraged, whereas systemically ill calves can benefit from systemic antibiotic treatment for the prevention of septicaemia or concurrent diseases. Ancillary treatments and specific preventive measures are discussed. Eimeriosis has a high economic impact on the farming industries due to direct cost of treatment and calf losses, but especially due to decreased performance of clinically as well as sub-clinically affected animals. Emphasis lies on prophylactic or metaphylactic treatment, since the degree of damage to the intestinal mucosa once diarrhoea has developed, makes therapeutic intervention unrewarding.

Simultaneous Determination of Tetracyclines Residues in Bovine Milk Samples by Solid Phase Extraction and HPLC-FL Method

INTRODUCTION

Tetracyclines (TCs) are widely used in animal husbandry and their residues in milk may resultin harmful effects on human. The aim of this study was to investigate the presence of TCs residues in various bovine milk samples from local markets of Ardabil, Iran.

METHODS

One hundred and fourteen pasteurized, sterilized and raw milk samples were collected from markets of Ardabil. Tetracycline, Oxytetracycline and Chlortetracycline (TCs) residues extraction carried out by Solid Phase Extraction method. Determination of TCs residues were performed by high performance liquid chromatography (HPLC) method using Fluorescence detector.

RESULTS

The mean of total TCs residues in all samples (114 samples) was 97.6 ±16.9ng/g and that of pasteurized, sterilized and raw milk samples were 87.1 ± 17.7, 112.0 ± 57.3 and 154.0 ± 66.3ng/g respectively. Twenty five point four percent of the all samples, and 24.4%, 30% and 28.6% of the pasteurized, sterilized and raw milk samples, respectively had higher TCs residues than the recommended maximum levels (100ng/g).

CONCLUSION

This study indicates the presence of tetracycline residues more than allowed amount. Regulatory authorities should ensure proper withdrawal period before milking the animals and definite supervisions are necessary on application of these drugs.

RetractedGeographical variation in cloacal microflora and bacterial antibiotic resistance in a threatened avian scavenger in relation to diet and livestock farming practices

The impact on wildlife health of the increase in the use of antimicrobial agents with the intensification of livestock production remains unknown. The composition, richness and prevalence of cloacal microflora as well as bacterial resistance to antibiotics in nestlings and full-grown Egyptian vultures Neophron percnopterus were assessed in four areas of Spain in which the degree of farming intensification differs. Differences in diet composition, especially the role of stabled livestock carrion, appear to govern the similarities of bacterial flora composition among continental populations, while the insular vulture population (Fuerteventura, Canary Islands) showed differences attributed to isolation. Evidence of a positive relationship between the consumption of stabled livestock carrion and bacterial resistance to multiple antibiotics was found. Bacterial resistance was high for semisynthetic penicillins and enrofloxacin, especially in the area with the most intensive stabled livestock production. The pattern of antibiotic resistance was similar for the different bacterial species within each area. Bacterial resistance to antibiotics may be determined by resistance of bacteria present in the livestock meat remains that constituted the food of this species, as indicated by the fact that resistance to each antibiotic was correlated in Escherichia coli isolated from swine carrion and Egyptian vulture nestlings. In addition, resistance in normal faecal bacteria (present in the microflora of both livestock and vultures) was higher than in Staphylococcus epidermidis, a species indicator of the transient flora acquired presumably through the consumption of wild rabbits. Potential negative effects of the use of antimicrobials in livestock farming included the direct ingestion of these drug residues and the effects of bacterial antibiotic resistance on the health of scavengers.

Evaluation of the hygienic quality and associated public health hazards of raw milk marketed by smallholder dairy producers in the Dar es Salaam region, Tanzania

A cross-sectional study was conducted to determine three parameters of the quality of the raw milk marketed by milk selling points (MSPs) in Dar es Salaam region. Total bacterial count (TBC) was used as an indicator of the microbial quality of the milk; antimicrobial residues were determined; and the California mastitis test (CMT) was used to screen for milk somatic cells as an indication of the mastitis level in the cows that provided the milk. Moreover, a water sample at each MSP was taken for bacteriological culturing. Finally, a questionnaire survey was conducted with the milk sellers at the MSPs to identify risk factors for poor milk hygiene. A total of 128 milk samples and corresponding water samples were collected from randomly selected milk selling points in Dar es Salaam region. The mean TBC was (8.2 +/- 1.9) x 10(6) cfu/ml, and major bacterial isolates from the milk samples were Escherichia coli (6.3%), Bacillus cereus (6.3%), Staphylococcus aureus (6.3%) and Streptococcus agalactiae (6.3%), Enterobacter aerogenes (5.6%) and Enterococcus faecalis (4.7%). In most cases, the organisms identified in milk corresponded to those isolated from the corresponding water samples. Of milk samples, 79.0% were positive to the CMT and 7.0% were positive for antimicrobial residues. TBC was normalized by log-transformation, and the possible predictors of TBC were identified by fitting two linear regression models. In a random effect model, water microbial quality, frequency of cleaning the milk containers, frequency of milk supply, milk storage time and the type of containers, and mixing of fresh and previous milk were significantly (p < 0.05) associated with the mean log TBC. In a fixed effect model, in addition to these indicators, water shortage, water source and the refrigerator condition were significantly (p < or = 0.01) associated with log TBC. It was concluded that the milk sold in Dar es Salaam region is of poor quality and is of public health significance.

Development of antimicrobial drug resistance in rectalEscherichia coliisolates from dogs hospitalized in an intensive care unit

OBJECTIVE

To determine whether duration of hospitalization in the intensive care unit (ICU) of a veterinary teaching hospital was associated with prevalence of antimicrobial resistance among rectal Escherichia coli isolates from dogs, whether antimicrobial treatment was associated with prevalence of antimicrobial resistance, and whether there were associations among antimicrobial drugs to which isolates were resistant.

DESIGN

Prospective observational study.

ANIMALS

116 dogs hospitalized in an ICU for >or= 3 days.

PROCEDURES

Rectal swab specimens were obtained every 3 days and submitted for bacterial culture for E coli. Isolates were tested for susceptibility to 12 antimicrobial agents by means of disk diffusion.

RESULTS

For each additional day that a dog was hospitalized in the ICU, the odds of being colonized with an E coli isolate resistant to 1 or more of the 12 antimicrobials tested increased by a factor of 1.5, independent of antimicrobial treatment. Dogs that were treated with enrofloxacin were 25.6 times as likely to be colonized by a quinolone-resistant E coli strain as were dogs that did not receive any antimicrobials. Significant correlations were found for resistance to agents in the extended-spectrum cephalosporin group and the quinolone group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that the proportion of rectal E coli isolates obtained from dogs housed for >or= 3 days in a veterinary teaching hospital ICU that were resistant to antimicrobial agents increased as the duration of hospitalization in the ICU increased. Thus, ICU hospitalization time should be as short as possible to prevent development of antimicrobial resistance among rectal E coli isolates.

Quantification and evaluation of antimicrobial drug use in group treatments for fattening pigs in Belgium

To control the emergence of antimicrobial resistance, knowledge of antimicrobial drug consumption is essential. Because consumption data are not available in Belgium, a study was conducted between March and October 2003 to investigate the antimicrobial drug consumption in pigs, using the treatment incidence based on the animal daily dose pig (ADDpig), the treatment incidence based on the used daily dose pig (UDDpig) (number of ADDpig or UDDpig/1,000 pigs at risk/day), and the ratio UDDpig/ADDpig. The sampling frame consisted of 821 pig herds that (a) used a closed or semi-closed production system, (b) were located in the most dense pig areas of Belgium, and (c) had at least 150 sows and 600 fattening pigs each. Of 50 randomly selected herds, all group treatments with antimicrobial drugs, applied to fattening pigs that were within 2 weeks of slaughter (median age 187 days), were collected retrospectively. The treatment incidence based on ADDpig for all oral and injectable antimicrobial drugs was 178.1 per 1,000 pigs at risk per day. The treatment incidence based on UDDpig shows that in reality fewer pigs were treated, namely 170.3 per 1,000 pigs at risk per day. Proportionally, the most often applied oral antimicrobial drugs were: doxycycline, amoxicillin, combination trimethoprim-sulphonamides and polymyxin E. The most often applied injectable antimicrobial drugs were long-acting amoxicillin and ceftiofur. The distribution of the UDDpig/ADDpig ratio per antimicrobial drug shows that 50-75% of the oral formulations were underdosed. Injectable formulations were almost always overdosed (>90%).

Oral vaccination of pigs with an invasive gyrA-cpxA-rpoB Salmonella Typhimurium mutant

The potency to protect pigs against colonization and against clinical salmonellosis was evaluated after oral immunization with a live gyrA-cpxA-rpoB Salmonella (S.) Typhimurium mutant (S. Tm. Nal2/Rif9/Rtt). Twenty 4-week-old male hybrid piglets were immunized orally, a control group received a placebo. Three weeks postimmunization, all pigs were challenged orally with a highly virulent S. Typhimurium DT104 strain. Clinical investigation revealed that immunization prevented the vaccinated pigs from clinical symptoms of salmonellosis. While all placebo-treated animals showed a 2-4-day episode of moderate to severe clinical symptoms, 90% of immunized pigs did not show any clinical signs at all. The bacteriological results showed a marked beneficial effect of the oral immunization. Vaccinated pigs showed a significantly decreased rate of colonization of the inner organs (42.5% versus 87.5%) when compared to the placebo-treated animals. Furthermore, in comparison to the non-immunized pigs, the vaccines developed a higher specific immunoglobulin (Ig)A antibody activity, but a significant lower IgM antibody activity in serum. The findings underline the ability of an attenuated oral live S. Typhimurium mutant to prevent clinical symptoms of salmonellosis in pigs and to significantly reduce the colonization of tissues and inner organs, as well as the shedding of S. Typhimurium.

Resistance of Salmonella Isolates in Germany

During 2000-2002 the National Veterinary Reference Laboratory for Salmonella (NRL-Salm) in Germany typed 11,911 isolates from animals, food, feed and the environment. All of them were tested for their susceptibility to 17 anti-microbial agents. Sixty-three per cent of all isolates were resistant and 40% were multiresistant (resistant against more than one anti-microbial). This general resistance level was strongly influenced by those specific serotypes which dominate the Salmonella epidemiology in Germany. Salmonella Typhimurium DT104 isolates from pig and cattle, and their resulting food products, were multiresistant in 98 and 94% of the cases respectively. During the period 2000-2003 an increasing quinolone resistance especially in Salmonella isolates from poultry and poultry meat (to 26%) and in S. Paratyphi B D-tartrate positive isolates (to 64%) could be observed. This increase was accompanied by a shift towards higher minimal inhibitory concentrations for ciprofloxacin.

Spread of Resistant Bacteria and Resistance Genes from Animals to Humans - The Public Health Consequences

The paper reviews the lines of evidence which link the use of antimicrobial drugs for food animals with the emergence of antimicrobial drug resistance in bacteria pathogenic to humans, with a particular focus on the public health aspects. Deductions from the epidemiology of food-borne infections, ecological studies, outbreak investigations, typing studies and direct epidemiological observations show that resistant bacteria are transferred from food animals to man. In addition to transfer in the food chain, exchange of mobile genetic elements among commensal and pathogenic bacteria contributes to the emergence of drug resistance. There is growing evidence that this has measurable consequences for human public health. One consequence is increased transmission supported by unrelated use of anti-microbials in humans. Other consequences are related to reduced efficacy of early empirical treatment, limitations in the choices for treatment after confirmed microbiological diagnosis, and finally a possible coselection of virulence traits. Recent epidemiological studies have measured these consequences in terms of excess mortality associated with resistance, increased duration of illness, and increased risk of invasive illness or hospitalization following infections with resistant Salmonella.

Evaluation of manometric respiration tests to assess the effects of veterinary antibiotics in soil

Extensive use of antimicrobials in veterinary medicine results in environmental exposure. Of major concern are microbial effects; including effects on nutrient soil cycles and antibiotic resistance. There is a need to assess the effects of these compounds in the environment. The application of standardized guidelines is relevant in studying many compounds. However there is a lack of special test methods designed for antibiotics. We validate manometric test flasks using glucose and a recalcitrant herbicide. The suitability of these tests for studying antibacterial agents is then investigated using two target functions (aerobic biodegradation and carbon transformation). Compound stability is quantified using HPLC techniques. Effects on total soil respiration in the biodegradation test are immediate and differ significantly from background. We show that compounds do not function as substrates, so effects are due to other soil processes, correlate well to sorption characteristics and are not dose dependent. This test provides details of relative antimicrobial potency towards soil microorganisms and can be used to rank compounds. However the test does not provide details on the nature or extent of specific microbial effects. In contrast, the carbon transformation test is more specific and provides a reproducible indication of dose effect relationships, which is more suitable in assessing the effects of these compounds in the environment. Presently, standard guidelines do not take into account the normal input of antibiotics into soils via contaminated sludge or manure. This should be corrected in future guidelines as these inputs alter microbial composition, organic matter, ionic strength and pH affect sorption and overall impact the test results.