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1.
A commercial broth microdilution system for testing the antimicrobial susceptibility of gram-positive cocci was compared with the standardized disk agar-diffusion method by testing 254 clinical strains of staphylococci and streptococci using both methods. A total of 2,794 parallel determinations were made with 92.3% complete agreement between the 2 methods; of the discrepancies encountered, 3.0% were minor, 2.5% were major, and 2.1% were very major. The results indicate that the commercial microdilution system may provide a reliable quantitative method for antimicrobial susceptibility testing of clinical isolates from animals.  相似文献   

2.
Fifty-one strains of Haemophilus pleuropneumoniae were tested for susceptibility to 27 antimicrobial agents using agar disc diffusion, broth-tube dilution and microdilution methods. There was generally good agreement between the interpretation of the disc diffusion inhibition zones and the actual minimal inhibitory concentrations obtained with the dilution methods. The agreement between the results obtained with the broth-tube dilution method and the microdilution method was very good. Three strains were resistant to penicillin, ampicillin, carbenicillin, methicillin and tetracycline. One of those was also resistant to chloramphenicol. Forty strains were resistant to streptomycin, 23 strains were resistant to novobiocin and seven were resistant to triple sulfa. It is thus necessary to consider resistance development against antimicrobial agents chosen for the treatment of pleuro-pneumonia in pigs caused by Haemophilus pleuropneumoniae.  相似文献   

3.
Phenotypic detection of methicillin resistance in coagulase-negative Staphylococcus (CoNS) of animal origin has been challenging due to the heterogeneous expression of mecA. To compare different phenotypic methods in predicting the mecA presence in CoNS, a total of 87 CoNS isolates from agricultural animals were analyzed in this study by agar dilution, disk diffusion, and broth microdilution. mecA was present in 81 CoNS isolates. Broth microdilution demonstrated the highest sensitivity of 100% in predicting the mecA presence, followed by 72.8% by agar dilution and 70.4% by disk diffusion. The results indicate that broth microdilution may be more suitable for predicting the presence of mecA in CoNS from animals than the other two methods, although staphylococcal species may also be a factor affecting the sensitivities of the methods as the top three staphylococcal species in this study were Staphylococcus lentus, Staphylococcus sciuri, and Staphylococcus xylosus (a total of 75 of 87).  相似文献   

4.
The results of three standard methods (broth dilution, agar dilution, disk diffusion) and an experimental modification of the microdilution method for determination of resistance to ampicillin, cephalotin, cloxacillin, neomycin, novobiocin, penicillin and streptomycin were compared using 151 Staphylococcus aureus isolates obtained from cases of mastitis. The accuracy of the dilution methods was compared by determination of minimum inhibition concentrations (MIC, MIC50, MIC90 and modal MIC) and by assessment of the agreement within the tolerance of +/-1 dilution step in 2-fold dilution series. The results of the dilution methods were further compared with those of the reference disk diffusion method and the strains were classified as sensitive or resistant using the interpretation criteria for human strains. The comparisons indicated that MIC characteristics and the final classification as sensitive or resistant were method-dependent. Resistance to aminoglycoside antibiotics was observed more often when using broth dilution methods, especially when the broth was supplemented with lactose.  相似文献   

5.
Francisella noatunensis subsp. orientalis (syn. F. asiatica) (Fno) is an emergent fish pathogen that causes acute to chronic disease in a wide variety of freshwater, brackish and marine fish. Due to the emergent nature of this bacterium, established protocols to measure antimicrobial susceptibility are lacking. In this project we compare three different methods to examine the antimicrobial susceptibility (Etest, broth microdilution and disk diffusion) of 10 different isolates of Fno from two different fish species and four different geographic outbreaks from 2006 to 2010. PCR mediated genomic fingerprinting (rep-PCR) performed on the different isolates confirmed genetic homogeneity amongst the different isolates. The in vitro susceptibility data presented here provides important baseline data for future research monitoring the development of antibiotic resistance among Fno isolates as well as provides invaluable data for the development of potential therapeutics.  相似文献   

6.
The determination of quantitative data (minimal inhibitory concentrations [MIC values]) using the broth microdilution method is considered the method of choice for in-vitro susceptibility testing of bacterial pathogens. For the inoculation of microtiter plates used in the broth microdilution method, an inoculation density of 5x10(5) CFU/ml has to be achieved according to the CLSI standard. In this study, it was shown that the requested CFU/ml corresponded to an optical density of 0.00027 of a bacterial suspension determined in a spectrophotometer at 625 nm (OD625).The comparison of susceptibility data of clinical isolates determined by agar disk diffusion and, in parallel, by broth microdilution confirmed the comparability of both methods. For most antibiotics the frequency of "very major errors" was below 10%. However, a higher frequency of errors was observed for combinations of antimicrobial agents and bacteria for which no valid breakpoints are available. The comparative testing of cephalothin showed a frequency of"very major errors" of 20.3% for staphylococci and 18.4% for Enterobacteriaceae; for apramycin the frequency of "major errors"was found to be 46.0% for Enterobacteriaceae. The reference strains as recommended in the CLSI Standard M31-S1 should be used for quality assurance.  相似文献   

7.
A C Tanner  C C Wu 《Avian diseases》1992,36(3):714-717
A technique is described for determining the antimicrobial susceptibility of Mycoplasma gallisepticum, using the Sensititre broth microdilution system. Fourteen M. gallisepticum field isolates and one reference isolate (R-strain) were tested in duplicate against seven antimicrobials. Isolates were susceptible to oxytetracycline, furaltadone, and lincomycin/spectinomycin, but not to amoxycillin and apramycin. Susceptibility to erythromycin and tylosin varied. These data are in agreement with those reported by other workers using more traditional methods, but this adaptation of the broth microdilution technique eliminates any variation attributable to the time-consuming preparation of antimicrobial dilutions associated with these methods.  相似文献   

8.
H. parasuis isolates (n=112) from pigs were tested for antimicrobial susceptibility against 23 antimicrobial agents by the disk diffusion method. All isolates were sensitive to Florfenico and most strains were sensitive to Cefotaxime (103/112; 92%), Ceftazidime (99/112; 88.4%), Chloramphenicol (90/112; 80.4%) and Gentamicin (85/112; 75.9%). High resistance levels to Nalidixic acid (84.8%), TMP (67.9%) and Trimethoprim+Sulfamethoxazole (58%) were observed. Genomic DNA extracted from 52 isolates resistant to at least seven antimicrobial agents was analyzed by PFGE and 46 distinct PFGE patterns identified. Diverse variation was observed between the drug-resistant H. parasuis isolates examined, suggesting that resistance traits were acquired independently by the respective isolates.  相似文献   

9.
OBJECTIVE: To describe antimicrobial susceptibility testing practices of veterinary diagnostic laboratories in the United States and evaluate the feasibility of collating this information for the purpose of monitoring antimicrobial resistance in bacterial isolates from animals. DESIGN: Cross-sectional study. PROCEDURES: A questionnaire was mailed to veterinary diagnostic laboratories throughout the United States to identify those laboratories that conduct susceptibility testing. Nonrespondent laboratories were followed up through telephone contact and additional mailings. Data were gathered regarding methods of susceptibility testing, standardization of methods, data management, and types of isolates tested. RESULTS: Eighty-six of 113 (76%) laboratories responded to the survey, and 64 of the 86 (74%) routinely performed susceptibility testing on bacterial isolates from animals. Thirty-four of the 36 (94%) laboratories accredited by the American Association of Veterinary Laboratory Diagnosticians responded to the survey. Laboratories reported testing > 160,000 bacterial isolates/y. Fifty-one (88%) laboratories reported using the Kirby-Bauer disk diffusion test to evaluate antimicrobial susceptibility; this accounted for 65% of the isolates tested. Most (87%) laboratories used the NCCLS (National Committee for Clinical Laboratory Standards) documents for test interpretation. Seventy-five percent of the laboratories performed susceptibility testing on bacterial isolates only when they were potential pathogens. CONCLUSIONS: The veterinary diagnostic laboratories represent a comprehensive source of data that is not easily accessible in the United States. Variability in testing methods and data storage would present challenges for data aggregation, summary, and interpretation.  相似文献   

10.
Forty-five isolates of Actinobacillus pleuropneumoniae were tested for susceptibility to 12 antimicrobial agents using a microdilution method for the minimal inhibitory concentration determinations. These results confirmed the high prevalence of A. pleuropneumoniae strains resistant to antibiotics as reported earlier using the disc diffusion method (Kirby-Bauer method). While 36% of the isolates were resistant to the penicillins, 47% were resistant to chloramphenicol and 68% were resistant to tetracycline. Minimal inhibitory concentrations for the resistant isolates were approximately 32 times higher than those for the susceptible isolates to the above antibacterial agents. The isolates were in general weakly susceptible or resistant to spectinomycin, lincomycin, tiamulin and spiramycin whereas most of them were susceptible to gentamicin, trimethoprim and erythromycin. The susceptibility pattern was similar throughout the 1980 to 1984 period. The 14 serotype 5 isolates were more resistant to tetracycline but less resistant to chloramphenicol and the penicillins than the 28 serotype 1 isolates.  相似文献   

11.
采用纸片扩散法对从湖北地区分离鉴定的86株致病性鸭疫里氏杆菌进行了体外药物敏感性测定.结果表明,耐药性高的药物为复方新诺明、青霉素、红霉素、呋喃唑酮和杆菌肽,耐药率分别高达100%、100%、88%、70%、67%;其次为环丙沙星、氧氟沙星、诺氟沙星,耐药率分别为40%、35%、35%;敏感度高的药物为氟苯尼考、头孢噻...  相似文献   

12.
The present study describes antimicrobial resistance patterns of Salmonella enterica subspecies enterica serovar Dublin (S. Dublin) in clinical submissions from calves and temporal and farm-type trends in antimicrobial resistance patterns of the isolates. A total of 300 isolates of S. Dublin were obtained from fecal or internal organs of calves fewer than 120 days of age originating from 84 dairies and 18 calf ranches from July 1998 to December 2002. The isolates were susceptibility tested to a panel of 10 antimicrobials using the disk diffusion assay. Temporal and farm-type trends in individual antimicrobial inhibition zone sizes were assessed and antimicrobial resistance patterns were described using cluster analysis. Isolates obtained from calf ranches compared with dairies exhibited decreased susceptibility to florfenicol, gentamicin, neomycin, sulfisoxazole, sulfamethoxazole/trimethoprim, and tetracycline. During the years 1998-2002, decreasing susceptibility was seen for ceftiofur, enrofloxacin, and sulfamethoxazole/trimethoprim. There were 20 different antimicrobial resistance patterns in the isolate set, indicating that S. Dublin has the ability to transfer and pick up resistance genes with relative ease. The trends seen in antimicrobial resistance in S. Dublin may likely be linked to antimicrobial drug use in young calves.  相似文献   

13.
The objective of this study was to investigate the perceived increase in resistance of Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) isolated from the lower respiratory tract of horses to trimethoprim-sulfamethoxazole (SXT). The recorded SXT-susceptibility results of 50 S. zooepidemicus isolates from the tracheal wash fluid of equine patients examined at Colorado State University Veterinary Teaching Hospital from each of 2 time periods (1987-1990 and 1997-2001) were compared and statistically analyzed using a cross-sectional study design. There was a statistically significant difference between the documented resistance of S. zooepidemicus isolated in the 1987-1990 time period (8%), using quantitative microbroth dilution, and the resistance reported for isolates from the 1997-2001 time period (42%), using Kirby-Bauer agar disk diffusion. Laboratory investigation revealed inadequate quality control of media and subsequent falsely reported resistance of S. zooepidemicus from 1997 to 2001 time period. This study demonstrates how minor deviations from prescribed laboratory-testing guidelines can have a major effect on antimicrobial susceptibility test results. The study also underscores the need for regular surveillance and monitoring of trends in antimicrobial susceptibility to detect and correct such problems. In addition, epidemiologists and others collecting data from laboratories should be cautioned to interact with the laboratory regarding interpretation of results of various testing methods to ensure accurate analysis and conclusions.  相似文献   

14.
The correlation between the antimicrobic standard disk agar diffusion procedure and a veterinary antimicrobic breakpoint minimal inhibitory concentration system was evaluated. Bacterial isolates representing 5 different genera were tested against 15 antimicrobics. There were 3,795 tests performed; 77.3% of the test results were in agreement, 22.6% were in disagreement. Thirty-one percent of the conflicting results were due to the organism being intermediate on the standard disk agar diffusion procedure. Results suggest that the breakpoint system needs more than 1 antimicrobic dilution per antimicrobic, or a change in some of the single dilutions in the breakpoint system would eliminate some of these discrepancies. Another possibility would be to utilize more than 1 panel design, i.e., 1 for gram-positive organisms, 1 for gram-negative organisms, and 1 for fastidious organisms.  相似文献   

15.
宁夏地区奶牛乳房炎金黄色葡萄球菌耐药性分析   总被引：4，自引：0，他引：4  
为了解宁夏地区奶牛乳房炎金黄色葡萄球菌的耐药情况,采用药敏纸片扩散法,测定了50株奶牛乳房炎金黄色葡萄球菌对常用的17种抗茵药物的耐药性.同时采用产色头孢菌素法进行β-内酰胺酶的检测,并采用苯唑西林纸片法进行耐甲氧西林金黄色葡萄球菌(MRSA)的检测.结果表明,所有菌株除了对利福平、万古霉素100％敏感以外,对其他15...  相似文献   

16.
采用微量肉汤稀释法和D-试验法检测64株凝固酶阴性葡萄球菌（CNs）对10种抗菌药物的耐药性,并用PCR方法分别检测头孢西丁耐药菌株和红霉素耐药菌株中mecA基因以及erinA、ermB、ermC和msrA基因的携带情况。结果表明,所有菌株均对万古霉素和甲氧苄啶／磺胺甲恶唑敏感;泰妙菌素为耐药率（65．6％）最高的抗菌药物,其次是红霉素、氧氟沙星和β-内酰胺类药物。28株（43．8％）CNS对青霉素耐药,其中26株对头孢西丁耐药（MRS）并且均携带mecA基因。30株（46．9％）CNS对红霉素耐药,其中24株为MLSB耐药表型,主要由ermB基因介导。总之,兽医临床CNs分离株对常用抗菌药物的耐药性不同,mecA基因和ermB基因的携带分别是兽医临床MRS和MLSB表型产生的主要原因。  相似文献   

17.
Plesiomonas shigelloides is a causal agent of gastroenteritis, sepsis and meningitis in humans. We examined the prevalence of P. shigelloides among great cormorants (Phalacrocorax carbo hanedae) in Japan and the antimicrobial susceptibility of isolates. P. shigelloides was isolated from 33 (47.8%) of 69 fecal samples from great cormorants in 2014. All 33 isolates were subjected to antimicrobial susceptibility testing using broth microdilution methods, which showed resistance to ampicillin (31 isolates, 93.9%), tetracycline (two isolates, 6.1%) and trimethoprim (one isolate, 3.0%). The high prevalence of P. shigelloides in the great cormorants implicates the possible microbiological risk to public health.  相似文献   

18.
Salmonella enterica serovar Dublin (S. Dublin) is a cattle-adapted Salmonella serovar, so if antimicrobial resistance in S. Dublin arises as a result of antimicrobial use this most likely occurs within the cattle reservoir without impact from antimicrobial use in humans. We tested the antimicrobial resistance of bovine-origin S. Dublin isolates from 1986 through 2004 using a standard disk diffusion method. High proportions of isolates throughout the time period were resistant to one or more antimicrobials, and a marked increase in resistance to ceftazidime occurred between 2000 and 2004. Dairy-origin isolates were more likely to be resistant to several antibiotics than were isolates from beef operations where exposure to antimicrobials is likely to be less frequent. Plasmid analysis of a subset of isolates also supported the hypothesis that antimicrobial resistance traits in the cattle-adapted serovar Dublin were acquired within the bovine host environment.  相似文献   

19.
Wildlife may be an important reservoir of antibiotic-resistant bacteria and resistance genes. In this pilot study, the prevalence and patterns of antimicrobial resistance in Escherichia coli cultured from wild herring gull (Larus argentatus) feces and human wastewater at Cape Cod, Massachusetts, USA, was compared. Antimicrobial susceptibility was tested using Kirby-Bauer disk diffusion with seven antimicrobial agents. A high proportion of antimicrobial agent-resistant E. coli isolates (59.2%) were detected in wastewater samples compared with a lower prevalence of 17.5% in gull feces. In addition, there was a large proportion of isolates with intermediate susceptibility (93.0%) in gull feces. Although similar resistance patterns and shared resistance genes suggest possible wastewater contamination of the local environment, the relatively low frequency of resistance and high prevalence of intermediate susceptibility detected in E. coli cultured from gull feces depict a complex model of antimicrobial resistance among E. coli strains of wildlife origin.  相似文献   

20.
常用抗菌药物对东北地区猪源链球菌的体外抗菌活性研究   总被引：3，自引：0，他引：3  
采用微量稀释法(27种药物)和琼脂扩散法(7类药物)分别对临床分离的101株猪源链球菌进行了体外耐药性研究。以美国临床检验标准委员会(CLSI/NCCLS)的临界浓度和抑菌圈直径做为判断标准,判定了其对27种药物的耐药性和7类药物的耐药谱。结果表明,临床分离的菌株以耐药菌为主,且100%的菌株呈多重耐药;对头孢菌素类(100%)、磺胺类药物(96%～100%)、大环内酯类(97%～99%)、四环素类(98%)、青霉素类(94%～97%)耐药性最为严重,氟喹诺酮类药物(48%～91%)耐药性次之,共有25种不同的耐药谱型。结果表明,在东北地区分离到的猪源链球菌以多重耐药为主。  相似文献   

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