Comparative in vitro efficacy of antimicrobial shampoos: a pilot study

This study compared the antimicrobial efficacy of shampoos against meticillin‐sensitive Staphylococcus pseudintermedius (MSSP), meticillin‐resistant S. pseudintermedius (MRSP), antibiotic‐sensitive Pseudomonas aeruginosa (PA), multidrug‐resistant P. aeruginosa (MDR‐PA) and Malassezia pachydermatis. Three isolates were incubated for 10, 30 and 60 min with each shampoo diluted in phosphate‐buffered saline. Aliquots were then incubated for 16–18 h on sheep blood agar (bacteria) or for 3 days on Sabouraud’s dextrose agar (Malassezia). The minimal bactericidal concentrations (MBCs) for chlorhexidine products (Malaseb^®, Pyoderm^®/Microbex^® and Hibiscrub^®) were 1:1,024–1:2,048 for MSSP and MRSP, 1:512–1:1,024 for PA and MDR‐PA, and 1:2,048–1:5,096 for Malassezia at all time points. The MBCs for benzoyl peroxide (Paxcutol^®) for MSSP and MRSP were 1:2–1:8 at 10 min, and 1:256 after 30 and 60 min. A 1:2 dilution was effective against Pseudomonas, and 1:512–1:1,024 dilutions were effective against Malassezia at all time points. The MBCs for ethyl lactate (Etiderm^®) for MSSP and MRSP were 1:2 at 10 min, and 1:2–1:16 after 30 and 60 min. A 1:2 dilution was effective against Pseudomonas, and a 1:512 dilution was effective against Malassezia at all time points. Chloroxylenol (Coatex^®) and acetic acid–boric acid (Malacetic^®) were not effective against MSSP, MRSP or Pseudomonas. Both were effective against Malassezia at 1:8–1:16 dilution at 10 min, and at 1:8–1:32 dilution after 30 and 60 min. In conclusion, chlorhexidine appeared to be the most effective topical biocide, and MRSP and MDR‐PA were no less susceptible than antibiotic‐sensitive organisms. These results should, however, be confirmed with larger numbers of isolates.     

Comparative in vitro antimicrobial efficacy of commercial ear cleaners

The aim of this study was to compare the antimicrobial efficacy of ear cleaners against Staphylococcus intermedius, Pseudomonas aeruginosa and Malassezia pachydermatis. Single isolates of each organism were incubated in duplicate at 38 °C for 30 min with each ear cleaner diluted 1/2 to1/256 in phosphate‐buffered saline. Positive and negative controls were included. Aliquots were then incubated for 16–18 h on sheep blood agar (bacteria) or for 3 days on Sabouraud's dextrose agar (Malassezia) at 38 °C. The lowest dilutions exhibiting 100% antimicrobial efficacy for S. intermedius were: Cleanaural^® Dog 1/32; Sancerum^® 1/16; Otoclean^® 1/4; EpiOtic^® 1/2; MalAcetic^® 1/2; and Triz Plus^® 1/2. The results for P. aeruginosa were Sancerum^® and Triz Plus^® 1/16; Cleanaural^® Dog and EpiOtic^® 1/8; Otoclean^® 1/4; and MalAcetic^® 1/2. Results for M. pachydermatis were: Cleanaural^® Dog 1/32; Sancerum^®, Otoclean^®, EpiOtic^® and Triz Plus^® 1/8; and MalAcetic^® 1/4. Cleanaural^® Cat, MalAcetic HC^® and Triz EDTA^® did not display any antimicrobial activity at any dilution. Antimicrobial activity appeared to be associated with the presence of isopropyl alcohol, parachlorometaxylenol and a low pH. The results of this study may help clinicians make evidence‐based decisions when selecting ear cleaners for use in individual cases.     

Comparative in vitro susceptibility of Bacteroides and Fusobacterium isolated from footrot in sheep to 28 antimicrobial agents

The agar dilution method was used to determine the bacteriostatic activity of 28 antimicrobial agents against 141 strains to the genus Bacteroides and 29 strains from the genus Fusobacterium. All organisms were isolated from clinical cases of ovine footrot. The strains were isolated from 125 Merino sheep, over a period of 2 years, from January 1987 to December 1988. The three ureidopenicillins studied (azlocillin, mezlocillin and piperacillin) proved to be the most effective antimicrobial agents. Chloramphenicol, metronidazole and tinidazole effectively inhibited the growth of Bacteroides spp., while phosphomycin was active against Fusobacterium spp.     

双葛止泻口服液抑菌剂用量筛选与抑菌效力研究

通过抑菌效力研究确定了双葛止泻口服液中抑菌剂的合理添加量。根据《中国兽药典》2015年版一部附录“1121抑菌效力检查法”要求,以金黄色葡萄球菌、铜绿假单胞菌、大肠埃希菌、白色念珠菌和黑曲霉为试验菌株,建立双葛止泻口服液抑菌效力检查方法,对不同苯甲酸钠含量的双葛止泻口服液进行抑菌效力测定,筛选出供试品中抑菌剂合理添加量。结果表明,0.3%的苯甲酸钠对微生物生长繁殖具有良好的抑制作用,且为最低有效剂量。因此,0.3%的苯甲酸钠可作为双葛止泻口服液的抑菌剂用量。     

In vitro study of the effectiveness of different dressings for debriding fibrin in blood clots from horses

Franz diffusion cells containing uniformly dehydrated equine blood clots to simulate fibrinous eschar were used to measure the rate of debridement of fibrin by novel and traditional wound dressings, under standardised conditions of temperature, pH and humidity. Significant increases in protein breakdown occurred within 24 hours with all the dressings, but not thereafter. In general, dressings hydrated in normal saline were better as debriding agents than dressings hydrated in water. Autolytic debriding agents were 47 per cent more effective than chemical debriding agents; specifically, hydrofibre and gauze dressings hydrated in saline broke down more than 3500 microg/ml of protein whereas dressings impregnated with proteolytic enzymatic agents digested less than 1400 microg/ml.     

Pseudomonas and Aeromonas isolates from domestic reptiles and study of their antimicrobial in vitro sensitivity

Veterinary Research Communications -     

几种脱毒剂对黄曲霉毒素B_1和玉米赤霉烯酮体外吸附脱毒效果的比较研究

文章采用酶联免疫法(ELISA),分析比较了市场上10种常见脱毒剂对黄曲霉毒素B1和玉米赤霉烯酮的体外脱毒能力。结果显示,不同的脱毒剂脱毒效果不同,且经过特殊方式处理后的蒙脱石不仅对黄曲霉度B1和玉米赤霉烯酮具有较好的吸附脱毒能力,其复合物稳定性也较好。     

Salmonella enterica isolates from faeces of domestic reptiles and a study of their antimicrobial in vitro sensitivity

From October 2001 to February 2002, the faecal samples of 305 reptiles (165 saurians, 99 ophidians and 41 chelonians) were bacteriologically examined to detect Salmonella enterica. S. enterica was isolated from 73 (23.93%) faecal samples including 44 (60.27%) samples collected from saurians, 15 (20.55%) from chelonians and 14 (19.18%) from ophidians; considering the number of samples taken for each reptile group, S. enterica was isolated from the 36.58% of chelonians, 26.66% of saurians and 14.14% of ophidians. The isolates were distributed among 38 serotypes. Sixty-nine (94.52%) isolates were resistant to erythromycin. About one-third of the isolates was resistant to sulfisoxazole (35.61%), gentamycin (32.88%), amoxycillin (31.51%) and ampicillin (27.40%). All but one of the isolates were sensitive to chloramphenicol. A high percentages of isolates were sensitive to enrofloxacin (84.93%), nitrofurantoin (80.82%), trimethoprim (76.71%) and tetracycline (75.34%).     

Comparative study on the in vitro and in vivo properties of two bovine herpesvirus-5 reference strains

Background

Bovine herpesvirus 5 (BoHV-5) is an alphaherpesvirus responsible for meningoencephalitis in young cattle and it is antigenically and genetically related to bovine herpesvirus 1. BoHV-5 outbreaks are sporadic and restricted in their geographical distribution, being mostly detected in the Southern hemisphere. The N569 and A663 strains are prototypes of the "a" and "b" subtypes of BoHV-5, however, scarce information about their in vitro and in vivo properties is currently available.

Methods

For the in vitro comparison between BoHV-5 A663 and N569 strains, viral growth kinetics, lysis and infection plaque size assays were performed. Additionally, an experimental infection of cattle with BoHV-5 A663 and N569 strains was carried out. Viral excretion, development of neurological signs, presence of specific antibodies in serum and nasal swabs and presence of latent BoHV-5 DNA in trigeminal ganglion, were analyzed. Histopathological examination of samples belonging to inoculated animals was also performed.

Results

The lytic capacity and the cell-to-cell spread was lower for the A663 strain compared to the N569 strain, however, the production of total infectious viral particles was similar between both strains. Concerning the in vivo properties, the A663 and N569 strains are able to induce similar degrees of pathogenicity in cattle.

Conclusions

Our results show that the A663 strain used in this study is less adapted to in vitro replication in MDBK cells than the N569 strain and, although slight differences were observed, both strains are able to induce a similar degree of virulence in the natural host.     

三株乳酸杆菌体外抑菌试验的研究

采用牛津杯法对3株乳酸杆菌菌液、菌体及其代谢产物进行体外抑菌试验,结果显示乳酸杆菌菌液及其代谢产物都有较强的抑菌活性,而菌体没有抑菌活性;代谢产物热稳定性较好,甚至能耐受100℃的高温,但受pH值的影响较大,随着pH值的升高抑菌活性逐渐降低,在弱酸、中性和碱性条件下将失去抑菌活性;代谢产物的抑菌活性不受过氧化氢酶、蛋白酶K、胃蛋白酶和胰蛋白酶等的影响。     

木犀草素对4种细菌体外抗菌活性研究

为研究木犀草素的体外抗菌活性,本试验采用肉汤微量稀释法测定木犀草素对化脓隐秘杆菌、大肠埃希菌、沙门菌和链球菌的最小抑菌浓度(MIC),并测定亚抑菌浓度木犀草素对4种细菌生长曲线的影响。结果表明,木犀草素对化脓隐秘杆菌的抑制作用最强,MIC为0.078g/L;对沙门菌的抑制作用次之,MIC值为1.25g/L;对大肠埃希菌和链球菌的抑制作用相对较弱,MIC值均为2.5g/L。木犀草素对4种试验菌株的生长均具有抑制作用,且随浓度的升高其抑菌作用增强(P<0.05)。     

草鱼对膨化和未膨化的菜籽、大豆离体消化研究

试验采用体外消化法研究了草鱼对菜籽、膨化菜籽、菜麦(菜籽 小麦1∶1)、膨化菜麦(膨化菜籽 小麦1∶1)、豆麦(大豆 小麦1∶1)、膨化豆麦(膨化大豆 小麦1∶1)6种饲料原料的消化能力。试验结果,1)草鱼对6种饲料原料的离体消化率为:膨化菜籽(23.46%)>菜籽(22.21%),膨化菜麦(26.95%)>菜麦(15.74%),膨化豆麦(32.79%)>豆麦(19.36%);对粗蛋白的离体消化率为:菜籽(46.36%)>膨化菜籽(38.51%)、膨化菜麦(39.24%)>菜麦(28.34%)、膨化豆麦(52.43%)>豆麦(46.16%);对粗脂肪的离体消化率为:膨化菜籽(44.71%)>菜籽(44.24%)、膨化菜麦(36.59%)>菜麦(29.00%)、膨化豆麦(43.54%)>豆麦(30.04%)。2)膨化对氨基酸生成速度产生不利的影响,但添加小麦的饲料原料组中(菜麦和豆麦)降低了膨化对氨基酸生成速度的不利影响。上述结果表明了草鱼对膨化饲料原料的消化要好于未膨化饲料原料,尤其是淀粉含量较高的饲料原料;由于膨化加工对饲料中氨基酸的破坏,导致了膨化饲料原料中蛋白质的有效性降低,但添加小麦可减少膨化对蛋白有效性的降低。     

Comparative quantification of the in vitro activity of veterinary fluoroquinolones

The aim of this study was to compare the in vitro antimicrobial activity of the veterinary fluoroquinolones against a panel of recently isolated porcine and bovine bacterial pathogens. The study used enrofloxacin as a benchmark against which other agents were compared, being the most common fluoroquinolone used in treatment of bovine and porcine infections. The activity of ciprofloxacin was also assessed as it is the main metabolite of enrofloxacin in cattle. Enrofloxacin and ciprofloxacin generally showed higher antibacterial activity, in terms of MIC(50) values, for most pathogen species when compared with marbofloxacin, difloxacin, danofloxacin and norfloxacin. Ciprofloxacin showed significantly greater in vitro antibacterial activity than enrofloxacin against M. haemolytica, P. multocida and E. coli, whereas enrofloxacin showed greater activity than ciprofloxacin against S. aureus. Marbofloxacin was significantly more active than enrofloxacin against M. haemolytica, E. coli and B. bronchiseptica but less active against P. multocida, S. aureus, coagulase negative Staphylococci, S. dysgalactiae, S. uberis, A. pleuropneumoniae and S. suis. Danofloxacin was significantly less active than enrofloxacin against P. multocida, E. coli, S. uberis, A. pleuropneumoniae and S. suis. Enrofloxacin and its metabolite ciprofloxacin showed the highest in vitro activities against most bovine pathogens tested and the porcine pathogens also showed a high degree of sensitivity to enrofloxacin. These data facilitate further pharmacokinetic/pharmacodynamic comparison of fluoroquinolones currently used in veterinary medicine.     

In vitro antimicrobial susceptibilities of three Porphyromonas spp and in vivo responses in the oral cavity of cats to selected antimicrobial agents

OBJECTIVES: To determine in vitro susceptibility of Porphyromonas gingivalis, P salivosa and P circumdentaria to seven antimicrobial agents by agar dilution and Epsilometer test methods and to assess the effectiveness of these antimicrobial agents in reducing the numbers of each Porphyromonas spp in the oral cavity of 16 domestic cats. DESIGN: A two-part prospective study involving in vitro antimicro-bial studies using Porphyromonas spp obtained from naturally occurring feline infections and in vivo antimicrobial response studies using client-owned cats with naturally occurring periodontal disease. PROCEDURE: Isolates (n = 25) of three feline Porphyromonas spp from the oral cavity and oral-associated disease were tested for their in vitro susceptibility to amoxycillin, amoxycillin-clavulanate, benzylpenicillin, clindamycin, doxycycline, erythromycin and metronidazole, using agar dilution and Epsilometer test methods. Digoxigenin-labelled whole chromosomal DNA probes directed against P gingivalis VPB 3492, P circumdentaria NCTC 12469T and P salivosa VPB 3313 were used to quantify organisms taken from two sample sites at the gingival margins of these cats prior to, and 5 days after, treatment with one of four commonly used antimicrobial products (amoxycillin-clavulanate, clindamycin, doxycycline or spiramycin-metronidazole). The response to treatment was assessed clinically for each cat. RESULTS: All isolates were susceptible in vitro to all seven antimicrobial agents using both methods. The numbers of P gingivalis were not reduced at the gingival sample sites by administration of amoxycillin-clavulanate for 5 days, although this treatment reduced the numbers of P salivosa and P circumdentaria to below detection levels in six of eight and two of three of sample sites, respectively; clinical improvement was not observed in cats treated with amoxycillin-clavulanate. Treatment with clindamycin, doxycycline or spiramycin-metronidazole resulted in clinical improvement and a marked reduction of all Porphyromonas isolates at the sample sites. CONCLUSION: The Epsilometer test is a simple and accurate method for determining the minimum inhibitory concentration for P gingivalis, P salivosa and P circumdentaria. All strains were susceptible in vitro to all the antimicrobial agents tested although clinical improvement of gingival disease was not noted with amoxycillin-clavulanate when given for 5 days at usual doses. This appears to be the first report of the disparity between the in vivo and in vitro susceptibility of oral bacterial strains to amoxycillin-clavulanate in the veterinary dental literature. This also appears to be the first report in which clinical and microbiological responses to commonly used antimicrobial agents for periodontal disease in cats has been documented and quantified. It was shown that treatment with clindamycin, spiramycin-metronidazole or doxycycline not only produced a substantial reduction in the number of Porphyromonas spp (in the majority of cases to below detection levels), but also resulted in substantial clinical improvement. This would indicate that these antimicrobial agents are useful adjunctive therapy to mechanical debridement in domestic cats.     

Corynebacterium pseudotuberculosis: in vitro susceptibility to 39 antimicrobial agents

The minimal inhibitory concentrations of 39 antimicrobial agents for 54 isolates of Corynebacterium pseudotuberculosis in vitro have been determined. The most active agents were penicillins, macrolides, tetracyclines, cephalosporins, lincomycin, chloramphenicol, and rifampicin. Most isolates were resistant to aminoglycosides, nitrofurans, polymyxins, nalidixic acid, and cycloheximide.     

Effect of bambermycins, in vitro, on plasmid-mediated antimicrobial resistance

The potential of bambermycins (a growth-promoting antimicrobial approved for turkeys, broilers, and swine) to overcome or control plasmid-mediated antimicrobial resistance was determined in a series of in vitro experiments. Four possible modes of action of bambermycins were studied: synergistic effect with 12 other antimicrobials, elimination of resistance (R) plasmids from Escherichia coli, selective killing or inhibition of E coli carrying R plasmids, and inhibition of R plasmid transfer. Bambermycins had no synergistic activity with the other drugs tested and had little effect on eliminating plasmids from host bacteria. Dependent on plasmid type, bambermycins decreased or increased transfer frequency of R plasmids. Bambermycins also selectively inhibited growth of bacteria harboring certain R plasmids.     

Determination of the in vitro susceptibility of feline tritrichomonas foetus to 5 antimicrobial agents

BACKGROUND: The nitroimidazole, ronidazole, has been demonstrated to have in vitro and in vivo activity against the protozoan Tritrichomonas foetus in cats. The purpose of this study was to evaluate the in vitro susceptibility of feline T. foetus isolates obtained from naturally infected cats to 5 antimicrobial agents and to compare the in vitro time kill of ronidazole and metronidazole. HYPOTHESIS: We hypothesized that nitroimidazoles have in vitro activity against T. foetus, whereas furazolidone, omeprazole, and paromomycin do not. ANIMALS: Fecal specimens were cultured from 4 naturally infected Bengal cats with a history of T. foetus-associated diarrhea. METHODS: A 24-hour susceptibility assay was performed on all 4 isolates for the 5 antimicrobial agents. A time-kill microdilution method was performed on 2 isolates for metronidazole and ronidazole. RESULTS: Paromomycin and omeprazole showed no in vitro effect at concentrations < or = 80 microg/mL. There was no significant difference in 24-hour susceptibilities among metronidazole, ronidazole, and furazolidone. In addition, only the results of the highest concentration tested (80 microg/mL) and concentrations of 1.25 and 2.5 microg/mL revealed significant differences in the rate of trophozoite killing, with ronidazole having a faster reduction in trophozoite survival. CONCLUSIONS AND CLINICAL IMPORTANCE: Time-kill assays demonstrated ronidazole had a higher lethal activity compared with metronidazole. These findings contrast with a previously published report and may reflect strain variation, different methodologies, or both. The lack of clinical response seen with metronidazole administration to treat feline trichomoniasis may not reflect inherent resistance but rather in vivo events involving drug distribution and pharmacokinetics.