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PubMed2001

Assessment of BMS284756 MIC and 5-microg disk diffusion quality control studies tested against seven American type culture collection strains.

BMS284756 is a novel des-fluoro(6)-quinolone with antimicrobial activity similar to recently developed fluorinated quinolones. The purpose of this investigation was to determine the appropriate disk diffusion and MIC quality control (QC) ranges for BMS284756 when used against commonly tested QC strains (M23-A2). The BMS284756 5-microg disk content was tested against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Hemophilus influenzae ATCC 49247, Streptococcus pneumoniae ATCC 49619 and Staphylococcus aureus ATCC 25923. In addition, Enterococcus faecalis ATCC 29212 and S. aureus ATCC 29213 were evaluated by the broth microdilution method. Seven laboratories tested 2 disk lots on 3 agar media or 3-4 broth lots over a 10 day period. A total of 420 zone diameter values and 210 or 280 MIC values per organism were generated. The following disk diffusion and MIC QC ranges were suggested for BMS284756 and the seven QC strains: E. coli ATCC 25922 (28-35 mm/0.004-0.016 microg/mL), E. faecalis ATCC 29212 (0.03-0.25 microg/mL), S. aureus ATCC 25923 (30-36 mm), S. aureus ATCC 29213 (0.004-0.016 microg/mL), P. aeruginosa ATCC 27853 (19-25 mm/0.5-2 microg/mL), H. influenzae ATCC 49247 (33-41 mm/0.002-0.008 microg/mL), S. pneumoniae ATCC (26-33 mm/0.016-0.06 microg/mL). The proportion of participant results observed within the proposed ranges was 97.4-98.8% and 94.6-100% for the disk diffusion and MIC tests, respectively.

Anti-Infective Agents↗

PubMedDate not supplied

In vitro susceptibility of 33 clinical case isolates of Xanthomonas maltophilia. Inconsistent correlation of agar dilution and of disk diffusion test results.

Xanthomonas maltophilia is an emerging nosocomial pathogen, possibly selected by a changing antimicrobial usage and patient population. In the present study, we tested the susceptibility of 33 recent clinical case isolates to 12 commonly employed antimicrobials. Trimethoprim-sulfamethoxazole (1:19 ratio) and doxycycline were uniformly the most active agents; ciprofloxacin and fleroxacin were slightly less active and, along with tetracycline and ceftazidime, more variable in their potency. Interestingly, the disk diffusion method routinely overstated the activity of ciprofloxacin (12% very major errors, 58% minor errors). The present in vitro data and the hitherto accumulated clinical experience suggest that in the absence of unequivocal clinical efficacy of ciprofloxacin against this increasingly recognized nosocomial pathogen, the decision to use ciprofloxacin or any other fluoroquinolone against these pathogens should rely preferentially on the dilution susceptibility test method results. In contrast, the present study confirms the excellent predictive value of trimethoprim-sulfamethoxazole, tetracycline, and fleroxacin disks as well as the higher (9% minor errors) inhibitory activity of these drugs. Hence, pending the elaboration of clinical efficacy data of alternative antimicrobial agents against X. maltophilia infections, trimethoprim-sulfamethoxazole remains a sound therapeutic choice.

4-Quinolones↗

PubMed1991

Evaluation of the E test for quantitative antimicrobial susceptibility testing of Helicobacter pylori.

The Progressive Diagnostics Manufacturers epsilometer test (E test; AB Biodisk, Solna, Sweden), a quantitative variant of the disk diffusion technique, was evaluated comparatively to an agar dilution method for the antimicrobial susceptibility testing of Helicobacter pylori. A collection of 79 H. pylori clinical strains, including isolates with known resistance to various antimicrobial agents, was tested against 12 different antimicrobial agents. All strains were tested on Columbia agar supplemented with 10% horse blood. Plates were incubated at 37 degrees C in microaerobic atmosphere (5% O2, 10% CO2), and readings were done after 3 days of incubation. In general, E test MICs were easy to interpret and the correlation between MICs by the agar dilution method and the E test was good, with 86 and 99.5% of results being within, respectively, 1 and 2 log2 dilution steps in a total of 936 tests. All strains of H. pylori with documented resistance to the tested agents were detected by the E test. Thus, the E test appears to be an easy and reliable method for determination of MICs of antibiotics for H. pylori, and it may offer an interesting alternative to MIC determination by the agar dilution technique.

Drug Resistance, Microbial↗

PubMed1987

Correlation between bactericidal activity of fosfomycin trometamol in an in vitro model of the urinary bladder and susceptibility testing.

The present study was undertaken to define an interpretative guideline for disk diffusion susceptibility testing with fosfomycin trometamol, a new antimicrobial agent which has been developed for the treatment of urinary tract infections. Two potencies of fosfomycin disk were used: 50 and 200 micrograms, prepared in the presence and absence of glucose-6-phosphate. To verify the reliability of the results obtained in susceptibility testing, we have also evaluated the bactericidal activity of fosfomycin trometamol versus sensitive and resistant strains in an 'in vitro' model simulating the hydrokinetic aspects involved in the treatment of bacterial cystitis. The data obtained evidenced the role of glucose-6-phosphate in antimicrobial susceptibility tests as well as the importance of the urinary antibiotic concentrations to define sensitive and resistant bacteria. On the basis of our results, we recommend that a 200-microgram disk of fosfomycin containing 50 micrograms of glucose-6-phosphate should be used in antimicrobial susceptibility testing with fosfomycin trometamol.

Computer Simulation↗

PubMed2005

Species prevalence and antimicrobial susceptibility of enterococci isolated in a tertiary care hospital of North India.

The present prospective study was carried out to determine the species distribution and antimicrobial susceptibilities of enterococci isolated from clinical samples in a tertiary care hospital of North India. Enterococcus species isolated from blood, urine, pus, sterile fluids and the hospital environment from October 2003 to January 2004 were identified by standard biochemical tests. Antimicrobial susceptibility testing was performed by the disk diffusion method as per NCCLS guidelines. Out of a total of 105 Enterococcus species recovered during the study period, E. faecium (42.90%) and E. faecalis (40.00%) constituted the predominant isolates. Enterococcus faecium was the commonest blood culture isolate while E. faecalis predominated pus and urine samples. Other species isolated were E. mundtii, E dispar, E. durans, E. avium, E. raffinosus and E. gallinarum. High-level aminoglycoside resistance was detected in 73.3% of isolates. Resistance to vancomycin, teicoplanin and linezolid was not detected. Prevalence of a wide variety of Enterococcus species in clinical samples together with their variable antimicrobial susceptibility patterns emphasizes the need for routinely carrying out detailed speciation and in vitro susceptibility testing of enterococcal isolates in the clinical bacteriology laboratory.

Anti-Bacterial Agents↗

PubMed2005

[Frequency and susceptibility patterns of non-fermenting gram-negative rods isolated from patients hospitalised in intensive care units of a tertiary care hospital].

UNLABELLED: The aim of the study was to assess frequency and susceptibility to antimicrobial agents of non-fermenting gram-negative rods isolated from clinical specimens obtained from patients requiring intensive care, with emphasis on profile of the unit. Identification of cultured isolates was done using automated VITEK and API systems (bioMerieux, France). Susceptibility to antimicrobial agents was tested by a disk-diffusion method according to the NCCLS recommendations. In total the analysis comprised 425 strains of non-fermenting gram-negative rods, constituting 58.9% of all isolates of gram-negative bacteria. In blood cultures predominated strains of A. baumannii (46.8%) and P. aeruginosa (40.4%), while in cultures of other clinical specimens these bacteria comprised 42.9% and 43.9% of isolates. Major differences were observed in frequency of these species on both ICU units. Strains of non-fermenting rods isolated from blood cultures comprised a lower percentage of strains susceptible to antimicrobials (particularly cefepime and carbapenems) than isolates cultured from other specimens. Strains of A. baumannii resistant to imipenem and meropenem were detected with a frequency of 12.5% and 26.7%, respectively. Resistance of P. aeruginosa strains to carbapenems was 62.2% and 44.3%, respectively. There was a relatively high percentage of strains susceptible to cefepime (82.0%), ceftazidime (78.9%), amikacin (77.8%) and piperacillin/tazobactam (69.7%). CONCLUSIONS: 1. There was a predominance (58.9%) of strains of gram-negative non-fermenting rods. 2. Isolates from blood cultures were characterised by a much higher percentage of resistant strains in comparison to other specimens. 3. Strains of A. baumannii resistant to carbapenems were recorded. 4. There were differences in frequency and antimicrobial susceptibility among the strains of P. aeruginosa and A. baumannii depending on the type of clinical specimen and ICU profile.

Anti-Bacterial Agents↗

PubMed2006

Lactobacillus bacteremia, species identification, and antimicrobial susceptibility of 85 blood isolates.

BACKGROUND: Data regarding antimicrobial susceptibility of clinical Lactobacillus isolates are scarce, and appropriate interpretation criteria for susceptibility tests are not available. METHODS: We examined 85 cases of Lactobacillus bacteremia, of which 47 cases have been included in our previous studies. Overall, 14 antimicrobial agents were evaluated by the E-test method, and these results were compared with disk diffusion test findings. The clinical outcomes of the patients and their antimicrobial treatments were registered. RESULTS: The antimicrobial susceptibility of Lactobacillus strains was species dependent. The considerable number of Lactobacillus rhamnosus (n=46), Lactobacillus fermentum (n=12), and Lactobacillus casei (n=12) strains available for testing made it possible to compare the susceptibilities within 1 species, as well. Of the 46 L. rhamnosus isolates, 22 were identified as L. rhamnosus GG type by pulsed-field gel electrophoresis. All Lactobacillus isolates demonstrated low minimum inhibitory concentrations (MICs) of imipenem, piperacillin-tazobactam, erythromycin, and clindamycin. MICs of vancomycin were high (>256 microg/mL) for all other species except Lactobacillus gasseri and Lactobacillus jensenii. Disk diffusion and E-test results were concordant. The MICs of cephalosporins varied; cefuroxime demonstrated a higher level of activity than did ceftriaxone. Benzylpenicillin and ampicillin MICs had variable ranges between different species. Combination therapy was given to 83% of the patients, but, in 54% of them, therapy included only 1 microbiologically active agent, according to results of the susceptibility tests. Mortality at 1 week was 12% among patients who presumably were receiving adequate treatment and 27% among patients who were receiving inadequate treatment (P=.131, by E-test). CONCLUSION: Most clinical Lactobacillus blood isolates demonstrated low MICs of imipenem, piperacillin-tazobactam, erythromycin, and clindamycin, but they had variable susceptibility to penicillin and cephalosporins.

Anti-Bacterial Agents↗

PubMed1984

Rapid antimicrobial susceptibility testing of isolates from blood cultures by direct inoculation and early reading of disk diffusion tests.

Disk diffusion tests, inoculated directly from positive blood cultures, were evaluated for accuracy of reading zone diameters after 4- and 6-h and overnight incubation. In comparisons with results from standard disk diffusion tests, the 4-h results were in agreement for 83% of tests with gram-positive organisms and 64% of tests with gram-negative organisms. When minor discrepancies were ignored, the 4-h readings were in agreement for 98% of the tests with gram-positive organisms and 95% of the tests with gram-negative organisms. After 6 h of incubation, 91% of the tests with gram-positive organisms and 86% of the tests with gram-negative organisms agreed with standard results. The agreement was 99% for tests with both gram-positive and gram-negative organisms when minor discrepancies were excluded. Very major discrepancies occurred in two tests (0.1%) with gram-positive organisms and were not observed in tests with gram-negative organisms. The frequencies of major discrepancies were 3.5% after 4 h, 0.6% after 6 h, and 0.7% after overnight incubation. Ampicillin and cephalothin tests with Escherichia coli and Klebsiella spp. accounted for 81% of the major discrepancies in tests with gram-negative organisms. Oxacillin tests accounted for more than half of the major discrepancies in tests with staphylococci. The results of this study, which did not include the newer antibiotics, indicate that direct susceptibility tests from blood cultures read after 6 h of incubation are more reliable than 4-h results and produce less than 1% major errors in comparisons with standard susceptibility tests.

Anti-Bacterial Agents↗

PubMed2005

[Comparison of frequency and susceptibility to antimicrobials of bacterial strains of the family Enterobacteriaceae isolated from patients hospitalised in intensive care units].

UNLABELLED: The aim of the study was estimation of frequency and susceptibility to antimicrobial agents of gram-negative rods isolated from clinical specimens obtained from patients requiring intensive care, with emphasis on profile of the unit. The analysis comprised strains of gram-negative rods isolated from patients of two intensive care units (ICUs) of a tertiary care hospital (1200 beds). Identification of cultured isolates was done using automated VITEK and API systems (bioMerieux, France). Susceptibility to antimicrobial agents was tested by a disk-diffusion method according to the NCCLS recommendations. In total the analysis comprised 722 strains of gram-negative rods. In blood cultures predominated strains of Enterobacter spp. (42.5%) and Klebsiella pneumoniae (37.5%). In cultures of clinical specimens other than blood 41.6% comprised strains of Klebsiella pneumoniae, 14.8% Escherichia coli and 14.4% Proteus mirabilis. Frequency of multi-drug resistant strains of bacteria of the family Enterobacteriaceae was much higher among blood isolates in comparison to strains cultured from other clinical specimens. There was a relatively high percentage of strains of Enterobacteriaceae susceptible to piperacillin and tazobactam (69.0%) and ceftazidime (54.6%). CONCLUSIONS: 1. All strains were susceptible to carbapenems. 2. There was a relatively high percentage of strains of gram-negative rods susceptible to piperacillin/tazobactam and ceftazidime. 3. Bacteria isolated from blood cultures were characterised by a much higher percentage of resistant strains in comparison to other specimens. 4. Longer stay in ICU promoted selection of strains resistant to antimicrobials.

Anti-Bacterial Agents↗

PubMed2006

Prevalence and antimicrobial susceptibility patterns of Shigella species in Asmara, Eritrea, northeast Africa.

BACKGROUND AND PURPOSE: Diarrheal diseases are an important cause of morbidity and mortality in children in developing countries. Of the bacterial causes of dysentery, Shigella are the major enteropathogens with outbreak potential and common development of antimicrobial resistance. This study determined the prevalence and antimicrobial susceptibility patterns of different spp. of Shigella in Asmara, Eritrea. METHODS: Diarrheic stool specimens of a total of 2,420 children were screened for Shigella organisms over a period of 3 years using standard methods. The Shigella isolates were tested for antimicrobial susceptibility pattern by the disk diffusion method. RESULTS: Of the 84 Shigella isolates, 54 were Shigella flexneri and 20 were Shigella dysenteriae type 1. High rates of resistance were observed against ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole; 6% of the S. flexneri isolates were resistant to nalidixic acid. CONCLUSION: The study emphasizes the need for continuous monitoring of the occurrence of Shigella organisms and their antimicrobial susceptibility pattern for the successful treatment and control of Shigella dysentery, and also for the development of public health policy for populations at risk for shigellosis.

Adolescent↗

PubMed1989

[In vitro antibiotic susceptibility of staphylococci].

In this study in vitro activities of different antimicrobial drugs against 1000 staphylococci were evaluated. Tested staphylococci were isolated from the clinical material of out patient and in patient sections. Susceptibility tests were done according to NCCLS Disk Diffusion Technic. The antimicrobial drugs evaluated in this study were; Vancomycin, ofloxacin, sulbactam-ampicillin, co-trimoxazole, tetracycline, erythromycin, tobramycin, methicillin, first and third generation cephalosporins and penicillin. Vancomycin was the drug of choice against resistant staphylococci. Ofloxacin, sulbactam-ampicillin, first generation cephalosporins and some aminoglycosides were more effective than others.

Aminoglycosides↗

PubMed2005

In vitro method to assess the antimicrobial activity and potential efficacy of novel types of wound dressings.

AIMS: To develop a simple, reproducible in vitro static diffusion method using cellulose disks and defined species to test antimicrobial efficacy of wound dressings. METHODS AND RESULTS: Cellulose disks were inoculated by immersion in cell suspensions of target species Staphylococcus epidermidis, Candida albicans and Fusobacterium nucleatum. Test and control wound dressings were cut into equal sized squares (25 x 25 mm) and applied to the surface of 10-mm thick tryptone yeast extract agar on test beds. Following a 2-h equilibration period, inoculated cellulose disks were inserted (one per dressing) at the interface between dressing and agar surface and a small weight applied over each square. At various sampling times, disks were removed and surviving cells enumerated by viable counts. Disk to disk variation for microbial loading was assessed using S. epidermidis for both initial (n = 16) and standard treatment (n = 16) conditions. The coefficient of variation was low (<5%) indicating good reproducibility for cell loading and treatment position on the test bed. Replicate assays (n = 6) using S. epidermidis and oxyzyme gels produced similar kill rates with low scatter (R2 > 0.9) indicating good reproducibility between assays. Significant differences (P < 0.05) in kill rates were observed for different target species, types of dressing and test bed conditions (+/-blood and nutrients). CONCLUSIONS: The method is reproducible and useful in tracking the death kinetics of test species, enabling the comparison of different types of dressing. SIGNIFICANCE AND IMPACT OF THE STUDY: The reported method has significant advantages over established test procedures; it can be applied equally across a wide range of target species (including anaerobes and yeasts), a wide range of conditions, and different types of surface dressings, including those relying upon oxygen diffusion.

Anti-Infective Agents, Local↗

PubMed1986

Cefpirome (HR810) disk diffusion susceptibility tests: confirmation of interpretive criteria using cefotaxime and cefoperazone-resistant strains and effects of blood supplemented media.

Cefpirome (formerly HR810) is a wide-spectrum, beta-lactamase-stable cephalosporin with antimicrobial activity against Pseudomonas species, Enterobacteriaceae, and gram-positive species. Reevaluation of the 30-microgram disk diffusion tests with commercially prepared disks using strains resistant to "third generation," cephalosporins confirms the proposed susceptibility breakpoint zone of greater than or equal to 18 mm (minimal inhibitory concentration correlate, less than or equal to 8.0 micrograms/ml) and the resistance breakpoint zone of less than or equal to 14 mm (minimal inhibitory concentration correlate, greater than or equal to 32 micrograms/ml). Major and minor interpretive errors were only 3.8%, and these errors could be further reduced (2.3%) by not testing methicillin-resistant Staphylococcus species. The addition of 5% sheep blood or chocolated blood to Mueller-Hinton agar slightly increased the cefpirome zone diameters (17.7-22.2 mm) for nearly 60% of Streptococcus faecalis strains tested.

Bacteria↗

PubMed1998

Resistance to amikacin and gentamicin among Gram-negative bloodstream isolates in a university hospital between 1989 and 1994.

OBJECTIVE: To characterize antimicrobial resistance patterns to amikacin (AN) and gentamicin (GM) among Gram-negative bloodstream isolates and to determine the possible relationship between use of AN and GM and the occurrence of antibiotic resistance during a 6-year period. METHODS: Standard media and techniques of isolation and identification were used. Antimicrobial susceptibility testing was performed with the disk diffusion method and API rapid ATB E strips. Data on consumption of aminoglycosides were collected by the central hospital pharmacy and were expressed as daily defined doses. RESULTS: One thousand nine hundred and four bloodstream isolates were tested for AN and GM susceptibility between 1989 and 1994. Activities of AN and GM remained high during the study period against most isolates of Gram-negative bacteria. No relationship could be observed between the use of AN/GM and the rate of AN/GM resistance. Nosocomial Gram-negative bloodstream isolates showed a higher degree of resistance towards both AN (3.9% of all nosocomial isolates) and GM (7.9%) than community-acquired isolates (1.8% toward AN and 3.1% towards GM, respectively). There was a significant increase (P=0.004) in the risk of GM resistance in patients with nosocomial Gram-negative bacteremia detected more than 14 days after admission. The proportion of GM-susceptible Pseudomonas aeruginosa isolates decreased linearly from 97% for infections acquired between day 3 and day 10 following admission to 80% for bacteremia developing 30 days or more after admission (P=0.008). CONCLUSIONS: AN and GM remain highly active antimicrobial drugs for treatment of GNB in times of growing resistance to cephalosporins and fluoroquinolones.

Journal Article↗

PubMedDate not supplied

Resistance mechanism for a number of non-typhoidic Salmonella strains isolated in Iaşi, Romania.

The aim of this study was to find a possible explanation for the resistance pattern of the selected strains and to evaluate the impact in case of isolating such strains. During the period February-March 1998, in the Pediatric Hospital "Sf. Maria" from Iasi, Romania, 12 non-typhoidic Salmonella strains, non-duplicates were isolated from stools of newborns and, in one case, from mother as well. Identification was done by standard methods, and sensitivity testing by disk diffusion method, against the following antimicrobials: Ampicillin (A), Amoxycilin/Clavulanic Acid (AMC), Tetracycline (T), Streptomycin (S), Cloramphenicol (C), Nalidixic Acid (NA), Ciprofloxacin (CIP), Cephalotin (KF), Cefuroxime (CXM), Ceftriaxone (CRO), Cefotaxime (CTX), Ceftazidime (CAZ), Aztreonam (AZT), Imipenem (IPM), Amikacin (AK). All strains showed resistance to: A, AMC, T, S, C, NA, CRO, CAZ, CXM, CTX, KF except one strain, CTX and CRO sensitive. The possible explanation is the production of an extended-spectrum beta-lactamase (ESbLA), detected by microbiological methods (Masuda and clover-leaf). Resistance transfer was realised by using the previously described method. In conjugation experiments we have obtained only one transconjugant, identified as E. coli, that has acquired all resistance determinants. This report highlights on the isolation of multiresistant non-typhoidic Salmonella strains in hospitalised patients without previous antibiotic treatment and possibility of detecting such strains by being aware of the correlation: resistance phenotype-resistance mechanism.

Adult↗

PubMed2005

Susceptibility testing accuracy of a CTX-M-type extended-spectrum beta-lactamase organism-producing population of Enterobacteriaceae: intermethod analysis for 9 beta-lactams.

To assess the wide geographical applicability of the current and proposed susceptibility breakpoint criteria for 9 beta-lactam antimicrobials, the performance characteristics of 2 standardized methods were analyzed by testing a contemporary collection of 354 isolates of Enterobacteriaceae, enriched (76; 21.5%) for extended-spectrum beta-lactamase (ESBL)-producing strains. Molecular characterization of 57 ESBL strains revealed that majority of the strains (94.7%) were CTX-M type, with a predominance (85.2%) of CTX-M-14 and -3 types, those types prevalent in China. Bloodstream isolates constituted 68.6% of the entire collection. The 9 beta-lactam antimicrobials analyzed were aztreonam, cefepime, cefotaxime, cefotetan, cefoxitin, ceftazidime, ceftriaxone, ceftizoxime, and cefuroxime. Reference broth microdilution minimal inhibitory concentration (MIC) results were compared to those zone diameters obtained by disk diffusion testing. The regression coefficient was acceptable for most antimicrobials, ranging from r = 0.84 (cefotetan) to r = 0.98 (cefotaxime, cefuroxime, and ceftriaxone). Using the current breakpoint criteria, the absolute intermethod categorical agreement was acceptable for 8 of the 9 antimicrobials (not cefoxitin, 85.1%) ranging from 92.6% (cefotaxime) to 97.8% (ceftazidime). Very major (false-susceptible) and major (false-resistant) errors were nil (0.0%) for 5 of the beta-lactams and minor errors ranged from 0.8% (cefotetan) to 14.1% (cefoxitin). The proposed (generally lower) MIC breakpoint criteria also had acceptable intermethod concordance ranging from 91.6% (cefoxitin) to 99.2% (cefotaxime and ceftriaxone). Furthermore, an improvement in the intermethod absolute categorical agreement ranging from +0.8% (ceftazidime) to +6.6% (cefotaxime) was observed for 7 of 9 antimicrobials tested, including the ESBL screening test compounds (aztreonam, ceftazidime, cefotaxime, and ceftriaxone). No modification of the susceptible breakpoint criteria, with removal of the intermediate category, was proposed for cefoxitin and cefuroxime, resulted in a shift of error type from minor to major or very major, but the categorical agreement improved (+ >or=1.2%) for both cephems. In conclusion, our results confirm that both the current and the proposed MIC breakpoint criteria with appropriately selected zone diameter correlates have acceptable intermethod error rates even when tested against an Enterobacteriaceae collection enriched with CTX-M-type ESBL-producing strains that are endemic in locations (China) outside the United States.

Anti-Bacterial Agents↗

PubMed1979

A rapid (4--6-hour) urine-culture system for direct identification and direct antimicrobial susceptibility testing.

This study evaluates a new direct rapid system for urine cultures, including detection and quantitation of positive specimens by Gram stain, direct identification by 4--6-hour incubation of sediment with reagent strips, and antibiotic susceptibility testing by direct (3--4-hour) disk-elution methods. Of 987 routine urine specimens, 121 had significant (less than or equal to 10(5) colony-forming units/ml) gram-negative bacilluria, of which 89% were detected by the Gram stain. Direct rapid identification was correct in 94%. Results of direct disk-elution antimicrobial tests showed overall agreement with results of standard disk diffusion of 93% of tests, and major discrepancies in 4%. For urine specimens with gram-negative bacilluria, this system permitted detection, quantitation, identification, and antimicrobial susceptibility testing in four to six hours with reasonable, though not complete, accuracy.

Anti-Bacterial Agents↗

PubMed1980

In vitro susceptibility of Haemophilus equigenitalis, the causative organism of contagious equine metritis 1977, to antimicrobial agents.

The in vitro susceptibility of recent clinical isolates of Haemophilus equigenitalis to various antimicrobial agents was determined by the disk diffusion test and the World Health Organization-International Collaborative Study agar dilution procedure. Ampicillin and tetracycline were the most active drugs. All strains were susceptible to beta-lactam antibiotics, chloramphenicol, trimethoprim-sulfamethoxazole, nalidixic acid, nitrofurantoin (Furadantin), and bacitracin. All but two strains were resistant to streptomycin, whereas all strains were susceptible to the other aminocyclitol antibodies. All strains were resistant to clindamycin, lincomycin, and metronidazole.

Animals↗