Post-antibiotic effect of cephalexin against isolates of Staphylococcus intermedius obtained from cases of canine pyoderma

The post-antibiotic effect in vitro (PAE) of cephalexin was determined according to a broth dilution method against 5 isolates of Staphylococcus intermedius obtained from cases of canine pyoderma. Two durations of exposure and 3 concentrations were tested. The PAE increased when time of exposure or concentration increased. The mean PAE ranged from 0.7 to 3.3 h. The PAE of cephalexin against Staph-ylococcus intermedius may be clinically relevant when selecting a dosage regimen to treat pyoderma in dogs.     

Fluoroquinolone resistance in Staphylococcus intermedius

Four canine isolates of S. intermedius resistant to enrofloxacin were isolated amongst a total of 429 screened. Two of these were shown to exhibit resistance also to marbofloxacin and ciprofloxacin. Whilst molecular studies have shown the mechanism of resistance to these quinolone antibiotics to be similar in a number of staphylococcal species, it was not possible to confirm this mechanism in Staphylococcus intermedius .     

Adherence of Staphylococcus intermedius to canine corneocytes in vitro

This study investigated the in vitro adherence of Staphylococcus intermedius to canine corneocytes, collected from a healthy dog using double-sided adhesive tape. Adherence was shown to depend on duration (P < 0.001) and temperature of incubation (P < 0.001) and the concentration of bacteria (P < 0.001). Isolates of S. intermedius from lesions of pyoderma were not generally more adherent to healthy canine skin than were isolates from healthy dogs. Significant differences in adherence were demonstrated between individual isolates within both groups (P < 0.001). The study suggests that among S. intermedius there is no correlation between virulence and adherence to canine corneocytes in vitro. The finding may be important for the potential use of avirulent variants of S. intermedius as antagonistic strains against canine pyoderma. However, more studies are needed to compare the adherence of the isolates to skin cells obtained from dogs with diseases predisposed to pyoderma.     

In vitro antimicrobial activity of orbifloxacin against Staphylococcus intermedius isolates from canine skin and ear infections

The objective of the study was to evaluate the in vitro activity of orbifloxacin against Staphylococcus intermedius strains isolated in France from canine skin and ear infections. The minimum inhibitory concentrations (MICs) of orbifloxacin against 240 field S. intermedius isolates (69 skin and 171 ear isolates) ranged from 0.016 to 8 mg l(-1), with MIC50 and MIC90 equal to 0.5 and 1 mg l(-1), respectively. Only one strain, a pyoderma isolate was resistant (MIC=8 mg l(-1)). Orbifloxacin was tested at different concentrations for killing rate against five isolates obtained from pyoderma cases and against a reference strain (Staphylococcus aureus ATCC 29213). Orbifloxacin expressed a concentration-dependent bactericidal activity against the S. aureus reference strain, but a time-dependent bactericidal activity against S. intermedius. Orbifloxacin induced bactericidal effect against the S. intermedius strains tested with concentrations equal to or two times MIC.     

Colonization of neonatal puppies by Staphylococcus intermedius

Abstract Cutaneous and mucosal carriage of Staphylococcus intermedius was determined in five Cavalier King Charles spaniel bitches, living in normal domestic environment, and their 18 puppies during the immediate prepartum period and after whelping, over a total of 8 weeks, using quantitative swab techniques. Within 8 h of birth S. intermedius was isolated from each puppy. The nose and mouth were the most frequently colonized mucosal sites (83 and 78%, respectively). At that time S. intermedius was isolated from the abdominal skin in 78% of the puppies. One day postpartum the mucosal populations increased significantly ( P  < 0.001) but fell 6 ( P  < 0.01) and 20 ( P  < 0.001) days later. Populations from abdominal skin reduced during the first and fourth weeks postpartum ( P  < 0.05 for both). This study indicates that in the domestic environment S. intermedius establishes itself soon after birth. The level of colonization by S. intermedius in the bitches seems to influence the colonization by pathogenic staphylococci in puppies.     

Use of multilocus enzyme electrophoresis to distinguish clinically important strains of Staphylococcus intermedius from the skin of dogs

AIMS: To use multilocus enzyme electrophoresis to determine the genetic structure of Staphylococcus intermedius from normal skin of dogs and those isolated from a variety of disease conditions and to distinguish clinically important strains in dogs. METHODOLOGY: The diversity amongst 129 isolates of S intermedius from the skin and mucosa of 32 healthy dogs and 120 isolates from diseased sites in 120 individual dogs was examined using multilocus enzyme electrophoresis. Associations among ETs were examined to determine the diversity of isolates. RESULTS: Twenty two ETs were distinguished comprising 21 containing isolates from diseased sites and 11 containing isolates from normal dogs. The majority of isolates (171 of 249; 69% were located in two ETs (ET1 and ET 4), that were not distinguishable phenotypically. ET 1 contained 94 isolates (54 isolates from healthy dogs and 40 isolates from diseased sites) and ET 4 contained 77 isolates (46 from healthy dogs and 31 isolates from diseased sites). Further, 77.5% of isolates from healthy dogs were present in ET 1 and ET 4 and 59% of isolates from diseased dogs belonged to the same two ETs. There was only a small difference in genetic diversity among isolates taken from healthy dogs (11 ETs; H = 0.182) and those isolates taken from clinical specimens from diseased dogs (21 ETs; H = 0.218). Of the 21 ETs from diseased sites, ET 16 contained all six isolates from Staphylococcal Scalded Skin Syndrome in racing Greyhounds. CONCLUSIONS: The small difference in genetic diversity between isolates from the skin and mucosa of healthy dogs and isolates from various diseases, as well as the presence of the majority of isolates in two ETs, is consistent with the role of S intermedius as an opportunistic pathogen. The confinement of all Staphylococcal Scalded Skin Syndrome isolates within one ET is confirmation of this entity as a distinct disease of dogs.     

Frequency and antimicrobial susceptibility of Staphylococcus species isolated from canine pyodermas

Specimens obtained from pyogenic skin lesions of 210 dogs were culturally examined for staphylococci. A total of 215 isolates of staphylococci were biotyped, using the biochemical tests contained in a commercial staphylococcal identification system. Of 201 coagulase-positive isolates, 197 were identified as Staphylococcus intermedius, 3 as S aureus, and 1 as S hyicus. Of 14 coagulase-negative isolates, 5 were identified as S epidermidis, 5 as S xylosus, 3 as S simulans, and 1 as S hominis. Antimicrobial susceptibility tests were done on all staphylococcal isolates, using the standard disk-diffusion method. Staphylococcus intermedius isolates were susceptible to cephalothin, methicillin, and gentamicin. Resistance to ampicillin, penicillin G, and tetracycline was frequent. Antibiotic resistance was not associated with the depth of skin infection. Resistance to ampicillin, penicillin, tetracycline, and trimethoprim-sulfamethoxazole was not associated with previous antibiotic use. Increased resistance to chloramphenicol, clindamycin, and erythromycin was associated with previous antibiotic therapy. Antimicrobial susceptibilities of the other Staphylococcus species isolated are reported, but the small numbers of these species precluded making meaningful comparison with S intermedius.     

Antimicrobial drug susceptibility of Staphylococcus intermedius clinical isolates from canine pyoderma

A total of 50 Staphylococcus intermedius strains isolated in France from canine pyodermas in 2002 were investigated for their susceptibility to various antimicrobial drugs. Antimicrobial susceptibility was assessed using a 2-fold serial dilution method in Mueller-Hinton agar, and the minimal inhibitory concentrations (MICs) were determined. About 62% of the 50 strains tested were producers of beta-lactamase and categorized as penicillin-resistant. About 26% demonstrated resistance to sulphonamides, 46% to oxytetracycline, 30% to chloramphenicol, 28% to streptomycin, kanamycin, neomycin or erythromycin, 22% to clindamycin, 6% to doxycycline, 2% to gentamicin, enrofloxacin, marbofloxacin or pradofloxacin. Acquired resistance was not observed to a clavulanic acid-amoxicillin combination, oxacillin, cephalosporins (cephalexin, ceftiofur and cefquinome), trimethoprim, a sulphamethoxazole-trimethoprim combination and florfenicol. About 42% were simultaneously resistant to three or more antimicrobial classes (multiresistance). All isolates with acquired resistance to erythromycin were also resistant to streptomycin and neomycin/kanamycin. About 22% of isolates exhibited cross-resistance between erythromycin and clindamycin and all clindamycin-resistant isolates also exhibited resistance to erythromycin. Resistance to penicillin, oxytetracycline and chloramphenicol was also positively associated with resistance to erythromycin and streptomycin.     

犬脓皮病耐甲氧西林伪中间型葡萄球菌抗菌药耐药性及消毒剂抗性研究进展

犬脓皮病是一类主要由耐甲氧西林伪中间型葡萄球菌（MRSP）感染而引起的化脓性皮肤病。葡萄球菌是一种人与动物均易感的细菌,常引起各种化脓性疾病,其中,MRSP作为一种动物源葡萄球菌还会成为耐药基因贮存库,可将耐药基因通过环境或食物链传给人类。近年来MRSP造成的皮肤疾病病例大幅上升,给感染的控制带来挑战。笔者综合了犬脓皮病致病菌的抗菌药耐药性及其消毒剂抗性的相关研究,从MRSP的致病机制出发,总结了MRSP通过破坏细胞免疫系统的功能导致感染发生的相关机制,简述了多个国家MRSP对抗菌药的显著耐药性与相关耐药基因,如mecA和cat基因等,介绍了MRSP对胍类消毒剂与季铵盐类消毒剂的抗性及抗性机制,对外排泵、基因调控与抗性基因的可转移性等多种机制进行了论述,同时为避免MRSP对抗菌药与消毒剂的共同耐药性对犬脓皮病的治疗造成干扰,笔者从移动遗传元件介导的获得性抗性与依赖于细菌细胞结构的固有抗性等方面系统地分析了MRSP对消毒剂抗性和抗菌药耐药性之间的争议与联系,以期寻找一种科学合理的治疗方案,为犬脓皮病的临床用药提供参考。     

Identification of protein A from Staphylococcus intermedius isolated from canine skin

Protein A was identified in cell wall-bound and secreted forms from Staphylococcus intermedius isolated from canine skin. A direct binding radioimmunoassay for the detection of bacterial surface Fc receptors identified 48 of 50 S intermedius isolates that contained cell wall-bound protein A. Using a competitive binding radioimmunoassay for the detection of Fc-reactive proteins in bacterial culture supernatants, we identified 9 of 50 clinical isolates of S intermedius that secreted measurable quantities of an Fc receptor into the culture medium. Concentrated culture supernatants from these isolates were analyzed by western blotting techniques and probed with either a radiolabeled human IgG Fc-specific probe or a radiolabeled affinity-purified chicken antibody against protein A. The studies reported here confirmed that Fc receptors are secreted by S intermedius isolates from dogs and are antigenically and functionally similar or are identical to staphylococcal protein A. Analysis of Fc receptor secretion by S intermedius strains, isolated from dogs with a variety of dermatologic conditions, suggested a trend between severity of skin disease and the extent of Fc receptor secretion.     

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.     

The use of fluoroquinolones in veterinary dermatology

The fluoroquinolones are a group of antibiotics with considerable application for use in veterinary dermatology. They are rapidly bactericidal against a wide variety of clinically important organisms including Staphylococcus intermedius and gram-negative enteric bacilli by virtue of interference with the supercoiling of bacterial chromosomal material. Their favourable pharmacokinetic features make them applicable in many animal species, and in a range of dose formulations. The only major clinical contraindication is that fluoroquinolones should not be given to young, rapidly growing dogs as they can induce a noninflammatory, erosive arthropathy. For many years the only veterinary-labelled fluoroquinolone available was enrofloxacin. The selection of a fluoroquinolone has become more complex now that there are more choices available. Orbifloxacin, difloxacin and marbofloxacin now join enrofloxacin on the veterinary market, although not all of these are licensed in every country. The use of fluoroquinolones in dermatology remains controversial. The authors recommend that fluoroquinolones be considered in circumstances where canine pyoderma has been refractory to appropriate 'first line' antibiotics. They are most useful in the management of recurrent pyoderma and in chronic, deep pyoderma with extensive scar tissue. In addition, fluouroquinolones frequently are the drugs of choice for canine ear infections caused by Pseudomonas aeruginosa.     

Colonization of the canine skin with bacteria

Abstract Aspects of colonization of the canine skin with bacteria are reviewed. Owing to variability in sampling techniques, anatomical sites involved and lack of temporal studies, there is still controversy as to which bacteria are residents or transients on the canine skin. The establishment of the cutaneous flora is determined by the ability of bacteria to adhere to canine corneocytes, to use available nutrients from skin secretions and to resist challenge from competing bacteria. Variations in humidity and temperature due to environment, skin folds or differences in the haircoat are also likely to have an effect. Much research has focused around Staphylococcus intermedius, the main pathogen of the canine skin but its cutaneous residency status remains questionable. Pathological conditions such as atopy and seborrhoea favour the colonization of S. intermedius and predispose to infection. Recent studies indicate that bacterial interference as a method of preventing colonization of pathogenic staphylococci may be feasible. Résumé— Les aspects de la colonisation de la peau canine par des bactéries sont étudiées. A cause de la variabilité des techniques de prélèvements, des sites anatomiques, et du caratère ponctuel des études, le doute subsiste toujours quant à savoir quelle sont les bactéries résidentes ou transitoires sur la peau de chien. L'établissement d'une flore cutanée est déterminée par la capacité de la bactérie à adhérer aux cornéocytes canines, à utiliser les nutriments disponibles à partir des sécrétions cutanées et à résister aux autres bactéries qui concourent à l'occupation des memes sites. Les variations d'humidité et de température, dues à l'environnement, aux plis de peau et aux différences de pelage jouent probablement un role. La plupart des études concernent Staphylococcus intermedius, l'agent pathogène principal de la peau du chien, mais son statut de résident cutané est toujours débattu. Des conditions pathologiques telles que l'atopie et la séborrhée favorisent la colonisation par S. intermedius et prédisposent à l'infection. Des études récentes indiquent que l'interférence bactérienne peut être envisagée comme une méthode de prévention de la colonisation cutanée par un staphylocoque pathogène. [Saijonmaa-Koulumies, L. & Lloyd, D. H. Colonization of the canine skin with bacteria (Colonisation de la peau canine par des bactéries). Veterinary Dermatology 1996; 7 : 153–162.] Resumen Se revisan algunos aspectos de la colonización bacteriana en la piel canina. Existe aún controversia sobre qué bacterias son résidentes o transitorias en la piel del perro, debido a la variabilidad en las técnicas de recolección, localización y falta de estudios temporales. El establecimiento de la flora cutánea depende de su capacidad de adhesión a los corneocitos, de utilizar los nutrientes de las secreciones cutáneas y de resistir la competencia de otras bacterias. También es probable que tengan un papel los cambios de humedad y temperatura por los pliegues cutáneos o las diferencias en el pelaje. Se ha centrado mucha investigación en Staphylococcus intermedius, el principal patógeno de la piel canina, aunque se sigue cuestionando su existencia como residente cutáneo. Situaciones patológicas como la atopia o la seborrea favorecen la colonización por S. intermedius y predisponen a infección. Algunos estudios recientes indican que es factible la interferencia bacteriana como método de prevenir la colonización por estafilococos patógenos. [Saijonmaa-Koulumies, L. & Lloyd, D. H. Colonization of the canine skin with bacteria (Colonizacion de la piel cannina con bacterias). Veterinary Dermatology 1996; 7 : 153–162.] Zusammenfassung— Es werden Aspekte der Besiedelung der Hundehaut mit Bakterien dargestellt. Entsprechend der Variabilität in der Probenentnahme, verwendeten anatomischen Regionen und dem Mangel an temporären Studien exisitieren immer noch unterschiedliche Ansichten, ob Bakterien auf der Haut des Hundes als resident oder transient gelten. Die Aufstellung der kutanen Flora wird durch die Fähigkeit der Bakterien bestimmt, sich an die kaninen Korneozyten anzuheften, verfügbare Nährstoffe aus den Hautsekretionen zu verwenden und sich gegenüber konkurrierenden Keimen zu behaupten. Veränderungen in Feuchtigkeit und Temperatur in Abhängigkeit von Umgebung, Hautfalten oder Unterschieden im Haarkleid scheinen ebenfalls einen Effekt zu besitzen. Viele Untersuchungen konzentrierten sich auf Staphylococcus aureus, der hauptpathogene Keim auf der Hundehaut, aber sein Status als residenter Keim bleibt fraglich. Pathologische Zustände wie Atopie und Seborrhoe begünstigen die Besiedelung mit S. intermedius und prädisponieren für eine Infektion. Kürzliche Studien zeigen, daß bakterielle Interferenzen als Methode zur Verhinderung der Ansiedlung von pathogenen Staphylokokken möglich sein könnten. [Saijonmaa-Koulumies, L., Lloyd, D.H. Colonization of the canine skin with bacteria (Besiedelung der Haut des Hundes mit Bakterien). Veterinary Dermatology 1996; 7 : 153–162.]     

Antimicrobial susceptibility patterns of canine Staphylococcus intermedius isolates from veterinary clinical specimens

Sixty-six Staphylococcus intermedius isolates from canine clinical specimens were tested for susceptibility to various antimicrobial agents by the Bauer-Kirby disk diffusion method and a commercial microdilution system. All isolates were susceptible to cephalothin, cloxacillin, gentamicin, methicillin, and vancomycin. Resistance to ampicillin, penicillin G, and tetracycline was frequent. There was an overall 87% agreement of results from the disk diffusion and microdilution methods for 10 antimicrobial agents. There was greater than or equal to 94% agreement between the 2 methods for 7 antimicrobics; discrepancies were minor.     

Antimicrobial susceptibility of Staphylococcus intermedius isolated from healthy and diseased dogs

A total of 90 strains of Staphylococcus intermedius isolated from dogs were examined for antimicrobial susceptibility. There were no significant differences in the distribution patterns of MICs between strains from 1982 to 1985 and those from 1999, and between strains from healthy dogs and those from diseased dogs. All of the strains were susceptible to ABPC, DMPPC, CEX, TDM, ERFX, BFLX, and FF at concentrations of 0.05 to 6.25 microg/ml. The MICs of OTC, KM, EM, AIV-TS, and LCM were distributed in a broad range of 0.1 to >100 microg/ml, indicating the existence of resistant as well as susceptible populations of S. intermedius. Thirty-three strains (36.7%) were resistant to one or more anitmicrobial agents such as OTC (n=32), KM (n=9), EM (n=7), AIV-TS (n=7), and LCM (n=7).     

Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphylococci in the UK, 1980–96

Abstract Disc sensitivity tests were carried out on 2296 isolates of non-pigmented, coagulase-positive staphylococcal isolates from dogs in referral practice over the period 1980–96. Ninety-eight isolates were from the ears, 1089 from other skin regions and 37 from mucosae. Resistance to penicillin increased from 69.0 to 89.3%. Oxytetracycline resistance remained at about 40%; resistance to erythromycin and lincomycin, and to co-trimoxazole peaked at about 20 and 15%, respectively, in 1987–89 but has since fallen. Only a single isolate resistant to cephalexin was found between 1986 and 1996. No resistance to co-amoxyclav, oxacillin, methicillin and enrofloxacin was demonstrated. Resistance of mucosal isolates was higher than those from skin. Multiple isolates from 90 dogs showed different resistance spectra in 56% of cases indicating that single swab samples are of limited value in determining optimal therapeutic antibiotics. Resumé 2296 souches de staphylocoques coagulase positifs, isolées á partir de chiens présentés en consultation référée entre 1980 et 1996, subirent des tests de sensibilité sur disques. 98 souches étaient d'origine auriculaire, 1098 d'autres origines cutanées, et 37 d'origine muqueuse. La résistance á la pénicilline augmenta de 69, 0 á 89, 3 pour cent. La résistance a l'oxytetracyline resta stable á environ 40 pour cent; les résistances á l'erythromycine et á la lincomycine, et au co-trimoxazole atteignirent 20 pour cent et 15 pour cent respectivement de 1987 á 1989 mais baissèrent ensuite. Une seule souche resistante á la cephalexine fut isolée entre 1986 et 1996. Aucune résistance á l'amoxycilline-acide clavulanique, Foxacilline, la methicilline, et l'enrofloxacine se fürent découvertes. Les résistances des souches d'origine muqueuse étaient plus nombreuses que celles des souches d'origine cutaneé. Des souches isolées par prelevement multiples chez 90 chiens montraient des spectres de résistance différents dans 56 pour cent des cas ce qui montre que des écouvillonages uniques ont un interèt limité pour le choix de la meilleure antibiotherapie. [Lloyd, D.H., Lamport, A.I., Feeney, C. Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphyloccoci in the United Kingdom, 1980–96 (Antibiosensibilité de souches de staphylocoques pathogènes canins d'origines cutanee et muqueuse au Royaume Uni de 1980 a 1996). Veterinary Dermatology 1996; 7 : 171–175.] Resumen A continuación el autor describe como discos de antibiograma fueron utilizados en 2.296 aislamientos caninos de no pigmentados estafilococos coagulasa positiva durante el periodo de 1980 a 1996; 98 aislamientos a partir del oido, 1098 de otras partes de la piel y 37 de mucosas. Se observó que las resistencias a la penicilina aumentaron de 69, 0 a 89,3 por ciento; a la oxitetraciclina permanecieron constantes, alrededor del 40 por ciento. Con respecto a la eritromicina y lincomicina asi como al cotrimoxazol, el nivel de resistencias alcanzó un pico máximo de alrededor 20 y 15 por ciento respectivamente en 1987–1989 para disminuir desde entonces. Solo un solo aislamiento desarolló resistencias a la cefalexina desde 1986 a 1996. No se han encontrado resistencias frente a la asociación amoxicilina-clavulanico, oxicilina, meticilina y enrofloxacina. Se demostró una resistencia superior en los aislamientos a partir de mucosa que aquellos a partir de piel. Diversos aislamientos realizados en 90 perros mostraron espectros de resistencias differentes en 56 por ciento de los casos, lo cual indica que únicamente muestras recogidas a partir de escobillon son de valor limitado a la hora de determinar una terapia antibiótica optima. [Lloyd, D.H., Lamport, A.I., Feeney, C. Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphyloccoci in the United Kingdom, 1980–96 (Sensibilidad a los antibioticós entre aislamientos cutanéos y mucosos de estafilococos patogénico en el Reino Unido, 1980–96). Veterinary Dermatology 1996; 7 : 171–175.] Zusammenfassung— Es wurden Resistenztests mit Antibiotika-Plättchen bei 2.296 nicht-pigmentierten, koagulase-positiven Staphylokokken-Stämmen durchgeführt, die von Hunden in einer Überweisungspraxis im Zeitraum von 1980 bis 1996 gewonnen worden waren. 98 Isolate kamen von den Ohren, 1089 von anderen Hautgebieten und 37 von den Schleimhäuten. Resistenzen gegenüber Penizillinen stiegen von 69,0 auf 89, 3%. Resistenzen gegenüber Oxytetracyclin blieben bei etwa 40%; Resistenzen auf Erythromycin bzw. Lincomycin und Co-Trimazole waren in den Jahren 1987 bis 1989 am höchsten mit 20 und 15%, sind seither jedoch weniger geworden. Nur ein einziges Isolat mit Resistenz gegenüber Cephalexin wurde zwischen 1986 und 1996 gefunden. Es zeigte sich keine Resistenz auf Co-Amoxyclaf, Oxacillin, Methicillin und Enrofloxacin. Die Resistenzen von Schleimhaut-Isolaten waren höher als die von der Haut. Mehrfachisolate von 90 Hunden zeigten Spektren mit unterschiedlichen Resistenzen in 56% der Fälle. Dies ist ein Hinweis, daß Einzelabstriche von begrenztem Wert sind, um optimal wirksame Antibiotika zu ermitteln. [Lloyd, D.H., Lamport, A.I., Feeney, C. Sensitivity to antibiotics amongst cutaneous and mucosal isolates of canine pathogenic staphyloccoci in the United Kingdom, 1980–96 (Sensitivität auf Antibiotika bei kutanen und Schleimhaut-Isolaten von pathogenen Staphylokokken des Hundes im Vereinigten Königreich, 1980 bis 1996). Veterinary Dermatology 1996; 7 : 171–175.]     

In vitro susceptibility of Staphylococcus aureus strains isolated from cows with subclinical mastitis to different antimicrobial agents

Sensitivity to commercial teat dips (nonoxinol-9 iodine complex and chlorhexidine digluconate) of 56 Staphylococcus (S.) aureus strains isolated from quarter milk samples of various German dairy herds treated with different teat dipping schemes was investigated in this study. The minimum inhibitory concentration was determined using a broth macrodilution method according to the German Veterinary Association guidelines. The main objective of the current study was to induce in vitro resistance induction of S. aureus to chemical disinfectants. Ten different strains were repeatedly passed ten times in growth media with sub-lethal concentrations of disinfectants. Nine strains showed a significant reduction in susceptibility to the nonoxinol-9 iodine complex but only one strain developed resistance to chlorhexidine digluconate. Stability of the acquired resistance was observed in all S. aureus strains adapted to the nonoxinol-9 iodine complex and chlorhexidine digluconate. In contrast, simultaneous resistance to different antibiotics was not observed in any of the ten investigated S. aureus strains. However, the isolates exhibited a high degree of resistance to penicillin G. Based on these results, resistance of S. aureus to chemical disinfectants may be more likely to develop if the chemicals are used at concentrations lower than that required for an optimal biocidal effect.     

Susceptibility of canine and feline Escherichia coli and canine Staphylococcus intermedius isolates to fluoroquinolones

OBJECTIVES AND DESIGN: 1) A prospective study to determine in vitro concentrations for a range of fluoroquinolones, gentamicin and amoxycillin-clavulanate required to inhibit growth of recently collected, feline and canine Escherichia coli and canine Staphylococcus intermedius isolates. 2) A comparative retrospective study to compare the minimum inhibitory concentrations (MICs) of ciprofloxacin, enrofloxacin and amoxycillin-clavulanate for archived canine E coli and S intermedius isolates collected ten to twenty years earlier, with those for recently collected isolates. PROCEDURE: Susceptibility was assessed using disk diffusion, agar dilution susceptibility testing and Epsilometer tests (E-tests) for both recently collected and archived isolates. RESULTS: All feline E coli isolates and recently collected canine S intermedius isolates were susceptible to all fluoroquinolones. There was a statistically significant increase in the MIC range of ciprofloxacin and enrofloxacin for recently collected E coli, and in the MIC range of amoxycillin-clavulanate for recently collected S intermedius isolates compared to archived isolates. Twelve of 59 recently collected canine E coli isolates were resistant to both ciprofloxacin and enrofloxacin. Resistant canine E coli isolates were associated with complicating host or infection site factors. CONCLUSION: This is the first report comparing the MICs for all veterinary fluoroquinolones currently available in Australia for a representative sample of canine and feline E coli and canine S intermedius isolates. Importantly, this study identified 12 of 59 canine E coli isolates resistant to fluoroquinolones and identified the development of low level resistance in canine E coli to ciprofloxacin and enrofloxacin and canine S intermedius to amoxycillin-clavulanate.