In vitro evaluation of topical biocide and antimicrobial susceptibility of Staphylococcus pseudintermedius from dogs

Background – Staphylococcus pseudintermedius is an important canine pathogen, and the emergence and widespread dissemination of meticillin‐resistant strains (MRSP) is of significant concern. Multidrug‐resistant infections may require alternative approaches, such as the use of topical therapy. There is minimal information about the in vitro susceptibility of meticillin‐susceptible S. pseudintermedius (MSSP) and MRSP to biocides and topical antimicrobials. Hypothesis/Objectives – The hypothesis was that clinical isolates of MSSP and MRSP would not have universal susceptibility to topical biocides and antimicrobials. The goal of this study was to assess the susceptibility of a collection of S. pseudintermedius isolates to selected antimicrobials and biocides. Animals – The study was performed on clinical isolates of MSSP and MRSP from dogs with skin and soft tissue infections collected throughout North America between 2006 and 2008. Methods – The minimal inhibitory concentrations (MICs) of chlorhexidine digluconate, benzalkonium chloride, triclosan, accelerated hydrogen peroxide, geranium oil, tea tree oil and grapefruit seed extract were tested for 25 MRSP and 25 MSSP isolates from dogs using the agar dilution method. The MICs of fusidic acid, bacitracin and mupirocin were determined using Etests. Results – Triclosan demonstrated excellent activity against all bacterial isolates, with no growth at the lowest concentration evaluated (MIC ≤ 0.5 μg/mL). Conversely, grapefruit seed extract did not inhibit growth at the highest concentration tested (MIC > 3.84 μg/mL). All isolates were susceptible to mupirocin, fusidic acid and bacitracin. There were no significant differences noted in the range, MIC₅₀ or MIC₉₀ between MSSP and MRSP isolates. Conclusions and clinical importance – While isolates were susceptible to most of the tested compounds, universal susceptibility to all compounds with potential antimicrobial activity cannot be assumed, and specific testing is required.     

Review of antimicrobial growth promoting agents available

Some antibiotics and synthetic chemotherapeutics of quinoxaline and nitrofuran groups have a practical value among the agents stimulating weight gain and feeding efficiency of farm animals commonly referred to as nutritive, ergotropic agents or growth promoters. In order to avoid undersirable results for human beings they should not be applied for therapeutic purposes; they should not bring about any resistance in microorganisms and should not carry the risk of lowering the therapeutic activity of antibiotics and chemotherapeutics; they should not be absorbed from the alimentary tract and should be rapidly eliminated from the animal body; they should not cause allergic reactions in animals or humans and should act chiefly against Gram-positive microorganisms. The following nutritive antibiotics are described: flavophospholipol (producing an ergotropic effect not only in young animals but also in ruminants; having an antiplasmidic action and restoring the sensitivity of some resistant bacteria towards antibiotics), avoparcin (also active in ruminants), virginiamycin, zinc bacitracin and bacitracin methylene disalicylate, grisin (having a broad spectrum of antibacterial activity, an antimycotic action; stimulating fertilisation and phagocytosis), vitamycin-A (active at low concentrations of retinol in the feed), lambdamycin, noziheptide, efrotomycin. Due consideration is given to some chemotherapeutics such as nitrovin, carbadox (having a broad spectrum an antimicrobial action; giving residues for a long period in the body of pigs), olaquindox (with a broad spectrum, active more on Gram-negative microorganisms, applied mostly as a therapeutic agent), cyadox (with broad spectrum and lower toxicity). Polyether (ionophorous) antibiotics with an anticoccidial action and with an ergotropic activity in ruminants (increasing the molar percent of propionic acid and decreasing that of acetic and butyric acid; suppressing the production of carbon dioxide and methane; enhancing the blood sugar content) are mentioned: monensin sodium, lasalocid sodium, salinomycin sodium, lonomycin and narazin.     

Antimicrobial resistance in staphylococci from animals with particular reference to bovine Staphylococcus aureus, porcine Staphylococcus hyicus, and canine Staphylococcus intermedius.

Besides their role as commensals on the skin and mucosal surfaces, staphylococci may be involved in a wide variety of diseases in animals. Staphylococcal infections in animals are mainly treated with antimicrobial agents and as a consequence, staphylococci from animal sources have developed and/or acquired resistance to the respective antimicrobial agents. Resistance statistics obtained from national monitoring programmes on staphylococci from cattle and pigs, but also from surveillance studies on staphylococci involved in diseases in dogs are reported and reviewed with regard to their comparability. This review mainly focusses on the genetic basis of antimicrobial resistance in staphylococci of animal origin. Particular attention is paid to resistance to those antimicrobial agents which are most frequently used in veterinary medicine, but also to antimicrobial agents, such as chloramphenicol and mupirocin, which are used in specific cases for the control of staphylococcal infections in pets and companion animals. In addition, plasmids and transposons associated with the respective resistance properties and their ways of spreading between members of the same or different staphylococcal species, but also between staphylococci and other gram-positive bacteria, are described.     

Antimicrobial resistance of feline staphylococci in south-eastern England

Staphylococcus aureus is reported as the predominant feline staphylococcal pathogen. There is concern that cats may transfer resistant staphylococci to humans. In this study, staphylococci were obtained from skin and mucosae of 20 domestic cats, 9 with lesions, and 10 healthy feral cats. Species were identified by DNase and API ID32 Staph tests. Of 187 isolates, 21.4% were coagulase-positive and predominately from lesional cats; 90% of these were Staphylococcus intermedius . Coagulase-negative species were isolated equally in all three groups. All isolates were susceptible to coamoxiclav, cephalexin and bacitracin. Twenty-two, including 18 coagulase-negative isolates, showed some resistance to cotrimoxazole, lincomycin, enrofloxacin or oxytetracycline. Two isolates were resistant to more than one antibiotic. More resistant isolates were obtained from feral cats ( P < 0.01). The results suggest that S. intermedius is the principal coagulase-positive species. Antibiotic resistance is generally low amongst feline staphylococci. Higher resistance amongst feral cats suggests exposure to environmental antibiotics.     

Screening of Staphylococcus aureus, Staphylococcus intermedius, and Staphylococcus schleiferi isolates obtained from small companion animals for antimicrobial resistance: a retrospective review of 749 isolates (2003-04)

Companion animal staphylococcal isolate antibiograms were screened retrospectively to determine the frequency of methicillin-resistant (MR) infection by Staphylococcus aureus, Staphylococcus intermedius, and Staphylococcus schleiferi. Rates of MR were: S. aureus 35%, S. intermedius 17%, and S. schleiferi 40%. Frequency of isolation of methicillin-resistant S. aureus (MRSA) from dogs and cats was similar, whereas methicillin-resistant S. intermedius (MRSI) and methicillin-resistant S. schleiferi (MRSS) were significantly more common in dogs. MRSS was more commonly associated with superficial (skin and ear canal) infections, whereas MRSA was more commonly associated with deep infections. The MR strain resistance pattern to other classes of antibiotics was also investigated. MRSA was resistant to the most classes of antibiotics, followed by MRSI, while MRSS maintained the most favourable susceptibility profile. MR staphylococci may pose a significant risk to animal and public health. Therefore, to avoid selecting for resistant strains in cases of suspected staphylococcal infection, clinicians should consider culture and susceptibility testing early in the course of treatment.     

Macrolides and lincosamides

Macrolides and lincosamides are first choice bacteriostatic antibiotics used in veterinary dermatology. The main antibiotics in these classes are erythromycin, lincomycin, clindamycin and tylosin. They are well absorbed if given orally and are able to penetrate well into infected skin. Their spectrum of action comprises bacteria commonly associated with skin infections, including staphylococci. Their main disadvantages are the rapid development of bacterial resistance and occasional gastroenteric upset, most often seen with erythromycin. More recently developed macrolides, such as azithromycin and clarithomycin, are bactericidal, have a larger spectrum of action, a longer endurance, less resistance and may be given once a day instead of two or three times daily.     

Strategies for management of recurrent pyoderma in dogs

Staphylococcal skin infection (pyoderma) is a common clinical problem in dogs. The infection can be either superficial or deep. Most cases of staphylococcal pyoderma occur secondary to a definable underlying cause. Treatment consists of finding the underlying cause and correcting it, if possible, and treating the pyoderma with antibiotics. Antibacterial shampoos may be used as adjunct treatment, but corticosteroid drugs should not be used. When canine pyoderma recurs in the absence of an identifiable underlying cause, several treatment strategies can be effective in eliminating recurrence or limiting its severity. Frequent antibacterial shampoos are an easy and sometimes effective method. Immunomodulatory drugs are variably effective. Some commercially available bacterins are clearly helpful in treating recurrent pyoderma. As a last resort, the clinician may opt to keep the patient on long-term antibiotic therapy. Such therapy may promote development and dissemination of resistant strains of Staphylococcus and should be used only if absolutely necessary.     

In vitro percutaneous absorption of fusidic acid and betamethasone 17-valerate across canine skin

The penetration of betamethasone 17-valerate and fusidic acid through dog skin was measured in vitro. In order to detect the small amounts of diffused compounds, a liquid chromatography-mass spectrometric method was developed with sensitivity limits for both compounds of 5 ng/ml. After application to the skin surface of a topical gel preparation containing these compounds at the anticipated therapeutic dose rate, about 10 per cent of the betamethasone 17-valerate penetrated the skin over a 24-hour period, with no significant metabolism of the ester. About 1.3 per cent of the applied dose of fusidic acid was similarly recovered. The results demonstrated rapid penetration of both compounds through the epidermis.     

Effect of bacitracin on tetracycline resistance in Escherichia coli and Salmonella

Tetracyclines and bacitracin are used extensively as a growth promotant and a therapeutic, respectively in livestock. In this study, we test whether there is an interaction between bacitracin and tetracycline that can select for an increase in microbial tetracycline sensitivity, using Escherichia coli and Salmonella as a model. We found via in vitro studies that bacitracin at sublethal concentrations preferentially selects for outgrowth of tetracycline-sensitive bacteria from among a population of tetracycline-resistant and tetracycline-sensitive E. coli and Salmonella strains. Most of the bacterial strains employed in our study were shown by PCR to possess the tetracycline resistance gene tet(A) or tet(C), either of whose activity is associated with tetracycline efflux. Bacitracin could be substituted for the lipophylic chelator, fusaric acid, used as a positive selective agent for tetracycline sensitivity. Together, these observations suggest that bacitracin-mediated selection for tetracycline sensitivity alters the function of tetracycline efflux proteins. Using bacitracin and tetracycline simultaneously may improve the effectiveness of the antibiotics, while decreasing the risk of selecting for a population of tetracycline-resistant microorganisms.     

In vitro susceptibility testing of meticillin-resistant and meticillin-susceptible staphylococci to mupirocin and novobiocin

Antimicrobials effective against meticillin-resistant staphylococci are limited. Mupirocin is a topical antimicrobial used to treat bacterial skin infections. Novobiocin is an oral antimicrobial approved for treatment of staphylococcal upper respiratory infections in dogs. This study reports the in vitro activity of mupirocin and novobiocin on meticillin-susceptible (MSS) and resistant staphylococci (MRS) from healthy dogs and dogs with superficial pyoderma. Staphylococci were isolated from skin swabs at four sites on healthy dogs and from lesions on dogs with superficial pyoderma. Staphylococci were identified by morphology and by catalase and coagulase testing. Speciation and susceptibility testing were performed by the Dade Microscan (W. Sacramento, CA, USA). Meticillin resistance was confirmed by an oxacillin screen plate. Novobiocin and mupirocin susceptibilities were tested by disc diffusion. Staphylococci were cultured from 61 healthy dogs (17 MRS and 44 MSS) and 30 dogs with pyoderma (15 MRS and 15 MSS), with higher proportions of MRS isolates in dogs with pyoderma (P=0.038; χ(2) test). For mupirocin, 79.5% (35 of 44) MSS and 82.3% (14 of 17) MRS isolates from healthy dogs, and 100% (15 of 15) MSS and 86.6% (13 of 15) MRS isolates from dogs with pyoderma were susceptible (MSS, P=0.094; MRS, P=1.0; Fisher's exact test). For novobiocin, 95.4% (42 of 44) MSS and 52.9% (nine of 17) MRS isolates from healthy dogs and 93.3% (14 of 15) MSS and 80% (12 of 15) MRS isolates from dogs with pyoderma were susceptible (MSS, P=1.0; MRS, P=0.148; Fisher's exact test).     

Effects of additives on in vitro ruminal fermentation: a comparison of monensin and bacitracin, another gram-positive antibiotic

Mixed ruminal bacteria (n = 4) were incubated in anaerobic media for 24 h in vitro with either hay, corn meal, protein hydrolyzate or hydrogen gas as the substrate. The ionophore monensin and the polypeptide antibiotic bacitracin were added to the incubation flasks at concentrations ranging from 0 to 10 or 40 mg/liter. As was expected, monensin decreased methane production, increased the ratio of propionate to acetate and decreased the deamination of amino acids. Monensin had little effect on methane production, however, if hydrogen gas was the fermentation substrate. Bacitracin, another gram-positive antibiotic with a distinctly different cellular target, was somewhat less potent than monensin, but it produced strikingly similar responses. This similarity of fermentation patterns suggested that monensin action in the rumen is probably due to its activity as a gram-positive antibiotic, and that any gram-positive antibiotic not suppressed by resistance may produce fermentation effects similar to those of monensin. The cellular action of monensin as an ionophore in membranes is probably little more than a means of inhibiting sensitive species. Many gram-positive antibiotics have little affect on ciliate protozoa or coccidia.     

Characterization of Pasteurella multocida mutants of low virulence

Ten temperature-sensitive mutants of the Clemson University (CU) vaccine strain of Pasteurella multocida have been developed and were characterized by phenotypic attributes such as carbohydrate fermentation, antibiotic resistance, and membrane protein profiles. Some mutants were found to have lost the ability to utilize some substrates, notably xylose and gluconate, whereas others were able to ferment additional carbohydrates such as arabinose and rhamnose. CU was found to be resistant to sulfisoxazole, of intermediate resistance to bacitracin, and sensitive to rifampin; the sensitivity to these three antibiotics varied among the mutant strains, but 60% were resistant to rifampin. Membrane protein profiles demonstrated some changes in major bands, and there was variation in 50% of the mutants in proteins in the 31 kilodalton range. All strains were assayed for the presence of several virulence factors, and many were found to produce siderophore and to exhibit some degree of complement resistance.     

Bacterial isolates and antimicrobial susceptibilities in equine bacterial ulcerative keratitis (1993--2004)

REASONS FOR PERFORMING STUDY: Bacterial ulcerative keratitis is a common and often vision-threatening problem in horses. Emerging bacterial resistance to commonly used topical antibiotics has been demonstrated. Previous antibiotic use may alter the antimicrobial susceptibility of bacterial isolates. OBJECTIVES: To document aerobic bacterial isolates and associated bacterial susceptibilities from horses with ulcerative keratitis treated at the University of Tennessee between January 1993 and May 2004 and determine whether prior antibiotic therapy affected antimicrobial susceptibility of the isolates. METHODS: Medical records from horses with ulcerative keratitis and positive aerobic bacterial cultures and antimicrobial susceptibility were evaluated. Clinical history regarding antibiotic therapy prior to culture was documented. RESULTS: Fifty-one aerobic bacterial isolates from 43 horses were identified. Streptococcus equi subspecies zooepidemicus was the most commonly isolated organism, accounting for 33.3% of all isolates, followed by Pseudomonas aeruginosa (11.8%), Staphylococcus spp. (11.8%) and Gram-negative nonfermenting rods (7.8 %). No resistance was noted amongst S. equi ssp. zooepidemicus to cephalothin, chloramphenicol or ciprofloxacin. Only 64 % of S. equi ssp. zooepidemicus isolates were sensitive to bacitracin. No resistance was noted among P. aeruginosa to gentamicin, tobramycin or ciprofloxacin. Antibiotic therapy with neomycin-polymixin B-bacitracin prior to presentation and culture was documented in 11/17 horses in which S. equi ssp. zooepidemicus was isolated and in 4/6 horses in which P. aeruginosa was isolated. Three horses received topical corticosteroids prior to culture, of which 2 had polymicrobial infections. CONCLUSIONS: S. equi ssp. zooepidemicus and P. aeruginosa were the most frequently isolated bacterial organisms in equine ulcerative keratitis. No significant trends in aminoglycoside or fluoroquinolone resistance were noted among these organisms. However, the resistance of S. equi ssp. zooepidemicus to bacitracin with common use of this antibiotic suggests that previous antibiotic therapy probably affects antimicrobial resistance. POTENTIAL RELEVANCE: Therapy prior to culture may play an important role in antimicrobial susceptibility of corneal bacterial isolates. Corticosteroid use may increase the risk of polymicrobial infections of corneal ulcers, leading to a worse prognosis. Although significant fluoroquinolone resistance has not been documented in the veterinary literature, these antimicrobials should be reserved for known infected corneal ulcers and not used for prophylaxis. Empirical antibiotic therapy should not only be guided by clinical signs, but also take into consideration previous antimicrobial and corticosteroid therapy.     

Topical fusidic acid/betamethasone-containing gel compared to systemic therapy in the treatment of canine acute moist dermatitis

The efficacy of a topical preparation containing 0.5% fusidic acid and 0.1% betamethasone-17-valerate was compared to a systemic therapy (comprising a combination of parenteral dexamethasone and oral clavulanate-potentiated amoxycillin) in the treatment of 104 dogs with acute moist dermatitis. Significant improvement was evident after seven days in both treatment groups in all clinical parameters assessed and there was no significant difference in the overall response between the two treatment groups. Staphylococcus intermedius was the most frequently isolated organism from swabs at the first visit (Day 0). No resistance to fusidic acid or clavulanate-potentiated amoxycillin was encountered. The study demonstrates no difference in the clinical improvement achieved in canine acute moist dermatitis following topical or systemic therapy and that both treatment regimes represent effective treatment options for the condition.     

Risk Assessment of Bacitracin Resistance as a Medicated Feed Additive

The aim of this study was to provide theoretical basis for regulatory departments to formulate risk management measures for bacterial resistance of animal origin.The point assessment method was applied to assess the risk of bacitracin resistance in animal origin foods of Chinese residents,according to the model of risk assessment analysis,based on the data from the monitoring report of the citizen's physiques in China in 2014,the fifth Chinese total diet study and the official website of European Medicine Agency.Dietary exposure to bacitracin was calculated by estimated daily intake,and hazard quotient (HQ) was used in risk characterisation to indicate risk level of health damage exposed to bacitracin.Firstly,through the way of hazard identification,the toxicity of bacitracin by oral ingestion was very low.But the pathogenic bacteria such as Enterococcus and Clostridium perfringens had developed resistance to bacitracin,with the resistance genes easily transferring to the human intestinal flora through bacteria commonness.Secondly,the hazard characterization indicated the toxicological ADI was 0.055 mg/(kg·BW),and the microbiological ADI was 3.9 μg/(kg·BW).Thirdly,exposure assessment showed that the maximum dietary exposure of bacitracin was in 2 to 7 age group among Chinese residents.And that of women through intake of dairy products was higher than men.Among 2 to 7 age group,dairy products contributed most to the dietary exposure of bacitracin,while meat was the largest contributor above 8 years old.Fourthly,risk characterization hazard quotient was 1.4901 for males and 1.4121 for females among Chinese residents aged 2 to 7 by calculation,and <1 among other age groups.Finally,the uncertainty analysis showed that the lack of monitoring data of bacitracin residues in animal foods,the lag of authoritative data collection and release,the absence of consumption data of aquatic products brought uncertainty to the results.In total,the risk of bacitracin resistance as a medicated feed additive through animal foods exposure was high in children aged 2 to 7 and moderate in other age groups.The maximum residue limit standard should be revised appropriately and risk management of bacitracin resistance need to be strengthened in imported animal foods.     

副溶血性弧菌耐药基因的研究进展

副溶血性弧菌为水产品主要致病菌之一,水产业和农业中抗生素的过量使用导致副溶血性弧菌对所推荐使用的抗生素产生了抗性,并且在副溶血性弧菌中已经发现了质粒和整合子等基因移动元件,更增加了与其他细菌发生耐药基因相互交换和重组的几率。对副溶血性弧菌的耐药研究现状、耐药机制和耐药基因的水平转移进行综述。     

Prophylactic use of antibiotics in surgery

"Sound and careful surgery is the sine qua non of wound management; antimicrobials are adjunctive." The key to successful use of prophylactic antibiotics in surgery is careful selection of cases and medication. There are no final rule or formulas that will always give optimal results. Listed below are some guidelines that may assis the clinician in determining the need and form of antimicrobial use. 1. The operation must carry a significant risk of bacterial contamination. Refined-clean and clean procedures should not be given prophylactic antibiotics. 2. Bacterial cultures should be taken when possible, and the medication used for prophylaxis should be effective against the organisms expected to be encountered. 3. Narrow spectrum antibiotics should be used to conserve the body's normal flora. Broad spectrum antibiotics needed to combat resistant infections should not be used for prophylaxis. 4. The antibiotic should be present in the wound in effective concentrations at the time of the incision and be maintained only as long as the risk of new bacterial contamination exists.     

Antimicrobial and heavy metal resistance in commensal enterococci isolated from pigs

Antibiotic resistance in animal isolates of enterococci is of public health concern because of the risk of transfer of antibiotic resistance isolates or resistance determinants to consumers via the food chain. In this study, phenotypic and genotypic resistance in 192 pig isolates of enterococci to ampicillin, avilamycin, avoparcin, bacitracin, flavophospholipol, gentamicin, narasin, tetracycline, tiamulin, tylosin, vancomycin, virginiamycin, copper and zinc were investigated by susceptibility test and molecular methods. Resistance rates varied between the species but all isolates were susceptible to ampicillin, avilamycin, avoparcin, gentamicin and narasin but resistant to tetracycline and tylosin and intermediately resistant to copper. Only Enterococcus gallinarum and Enterococcus casseliflavus were resistant to vancomycin and virginiamycin resistance was present in less than half the Enterococcus faecium isolates. Zinc resistance was largely confined to Enterococcus faecalis but bacitracin resistance was uncommon in E. faecalis in comparison with the other species. Tiamulin resistance was common in all species except E. casseliflavus. Resistance to flavophospholipol was detected in most E. faecium isolates and in a high proportion of E. gallinarum, E. casseliflavus and E. hirae/durans but was only found in one isolate of E. faecalis. No tetO, rplC, rplD, vanA, vanB, vatA and vatD genes were found. The presence of ermB, tetL, tetM, tcrB, aac6-aph2, tetK, tetS, vanC1, vanC2, lsaA, lsaB and vatE varied between the species and largely corresponded to the susceptibility phenotype. The findings show that resistance to antibiotics of high clinical significance for nosocomial Enterococcus infections is absent, whereas antimicrobial resistance was detected for some other antibiotics including bacitracin, flavophospholipol, tetracycline, tiamulin, tylosin and virginiamycin.     

Antibiotic resistance of canine Staphylococcus intermedius group (SIG)--practical implications

A total of 221 SIG strains were isolated from clinical samples of canine origin submitted to the Diagnostic Laboratory of the Division of Bacteriology and Molecular Biology at the Warsaw University of Life Sciences in Warsaw during the period 2006-2010. The aim of the study was to investigate the frequency of prevalence of methicillin-resistant SIG strains and to determine the MIC values of cephalotin, amoxicillin/clavulanic acid, ciprofloxacin, clindamycin, gentamicin, chloramphenicol, mupirocin for a collection of randomly selected 79 strains belonging to Staphylococcus intermedius group (SIG), including 23 mecA-positive and 56 mecA-negative strains. All isolates were identified as belonging to SIG based on their phenotypic properties and PCR amplification of S. intermedius-specific fragment of the 16S rRNA gene. The mecA gene was detected in 26 (12%) of 221 SIG strains. All tested mecA-negative SIG strains were susceptible to amoxicillin/clavulanic acid and cephalotin. One of the 56 mecA-negative SIG strains was resistant to ciprofloxacin, six (11%) to gentamicin. It was found that sixteen (29%) of 56 mecA-negative SIG strains were resistant to clindamycin. Most of the mecA-positive SIG strains were resistant to ciprofloxacin (96%), clindamycin (96%), and gentamicin (96%). Only one MRSIG strain was resistant to chloramphenicol. All examined mecA-positive SIG strains were found to be susceptible to mupirocin. Our results imply that staphylococcal multidrug resistance has become more prevalent, which could lead to difficulties in effective treatment. With some resistant strains the only therapeutic possibility are antimicrobial agents important in human medicine. New regulations for veterinary medicine concerning appropriate therapy of infections caused by multidrug-resistat staphylococci are needed.     

Antibiotic use and resistance in animal farming: a quantitative and qualitative study on knowledge and practices among farmers in Khartoum, Sudan

Antibiotic resistance is a major emerging global public health threat. Farmers in the Khartoum state are believed to misuse antibiotics in animal farming leading to daily exposure to resistant bacteria and antibiotic residues. Hence, farmers are at potential risk exposure to bacteria, zoonotic infection and toxicity. We hypothesized that farmers' misuse of antibiotics could be due to their ignorance of the importance of optimal use of antibiotics, the potential health hazards and the economical waste associated with antibiotic misuse practices. In the present study, we investigated knowledge and practices among farmers regarding antibiotic use and resistance. For this purpose, a cross-sectional study was conducted in Khartoum state where data were collected from 81 farmers using structured interviews. Data were analysed both quantitatively and qualitatively. Fifty-two per cent of farmers were uneducated or had studied for < 6 years. The majority reported antibiotic use for treatment and prevention while only 5% stated use for growth promotion. Antibiotic group treatment for both sick and healthy animals was commonly practiced among most farmers. The most commonly used group of antibiotics was the quinolones, which was reported by one-third. Only 30% of the farmers had heard of antibiotic resistance and provided their definition. Almost half were not aware of the commonly transferred zoonotic infections between humans and animals. The farmers consume 1-2 meals/day from their own farm products. A significant association between low education, poor knowledge of farmers on antibiotic use, antibiotic resistance and zoonotic infections was found. This association may play a vital role in the present practiced misuse of antibiotics. Our findings on farmers' practices could be used as baseline information in defining the gaps related to antibiotic use and resistance in animal farming in Sudan. It can thus serve as a foundation for future interventions.