Antifungal susceptibility testing practices in mycology laboratories in France, 2018.

A survey of mycology laboratories for antifungal susceptibility testing (AFST) was undertaken in France in 2018, to better understand the difference in practices between the participating centers and to identify the difficulties they may encounter as well as eventual gaps with published standards and guidelines. The survey captured information from 45 mycology laboratories in France on how they perform AFST (number of strains tested, preferred method, technical and quality aspects, interpretation of the MIC values, reading and interpretation difficulties). Results indicated that 86% of respondents used Etest as AFST method, with a combination of one to seven antifungal agents tested. Most of the participating laboratories used similar technical parameters to perform their AFST method and a large majority used, as recommended, internal and external quality assessments. Almost all the participating mycology laboratories (98%) reported difficulties to interpret the MIC values, especially when no clinical breakpoints are available. The survey highlighted that the current AFST practices in France need homogenization, particularly for MIC reading and interpretation.

Antimicrobial susceptibility testing by Australian veterinary diagnostic laboratories.

BACKGROUND: The national strategy for tackling antimicrobial resistance highlights the need for antimicrobial stewardship in veterinary practice and for surveillance of antimicrobial susceptibility in veterinary pathogens. Diagnostic laboratories have an important role in facilitating both of these processes, but it is unclear whether data from veterinary diagnostic laboratories are similar enough to allow for compilation and if there is consistent promotion of appropriate antimicrobial use embedded in the approaches of different laboratories to susceptibility testing. METHODS: A cross-sectional study of antimicrobial susceptibility testing and reporting procedures by Australian veterinary diagnostic laboratories was conducted in 2017 using an online questionnaire. All 18 veterinary diagnostic laboratories in Australia completed the questionnaire. RESULTS: Kirby-Bauer disc diffusion was the method predominantly used for antimicrobial susceptibility testing and was used to evaluate 86% of all isolates, although two different protocols were used across the 18 laboratories (CLSI 15/18, CDS 3/18). Minimum inhibitory concentrations were never reported by 61% of laboratories. Common isolates were consistently reported on across all species, except for gram-negative isolates in pigs, for which there was some variation in the approach to reporting. There was considerable diversity in the panels of antimicrobials used for susceptibility testing on common isolates and no consistency was apparent between laboratories for any bacterial species. CONCLUSION: We recommend that nationally agreed and consistent antimicrobial panels for routine susceptibility testing should be developed and a uniform set of guidelines should be adopted by veterinary diagnostic laboratories in Australia.

A Statistical Evaluation of Methods of In-Vitro Growth Assessment for Phyllosticta citricarpa: Average Colony Diameter vs. Area.

Fungal growth inhibition on solid media has been historically measured and calculated based on the average of perpendicular diameter measurements of growth on fungicide amended media. We investigated the sensitivity of the calculated area (DA) and the measured area (MA) for assessing fungicide growth inhibition of the ascomycete, Phyllosticta citricarpa on solid media. Both the calculated, DA and the actual measured area, MA were adequate for distinguishing significant treatment effects of fungicide on fungal growth, however MA was more sensitive at identifying significant differences between the controls and fungicide concentrations below 5 ppm.

Evaluation of polymyxin susceptibility profile among KPC-producing Klebsiella pneumoniae using Etest and MicroScan WalkAway automated system.

Determination of polymyxin susceptibility profile is important to monitor resistance rates and for implementing control measures for polymyxin-resistant carbapenem-resistant Enterobacteriaceae. Some laboratorial methods have been used to determine the polymyxin susceptibility profile. However, the performance of MicroScan WalkAway has been poorly reported for KPC-producing Klebsiella pneumoniae, so far. To evaluate two different methods, Etest and the MicroScan automated system, in determining minimal inhibitory concentration (MIC) of polymyxin among KPC-producing K. pneumoniae isolated from patients in two care units (ICUs) of a tertiary hospital in Porto Alegre, Southern Brazil. A total of 101 KPC-Kb isolates were obtained from rectal swabs and clinical specimens (urine, blood, and endotracheal aspirate). Colistin and polymyxin B MICs were determined using MicroScan WalkAway automated system and Etest, respectively. Discrepant results were resolved by broth microdilution (BMD). MicroScan showed 88.1% of sensitivity for predicting polymyxin B resistance in KPC-producing K. pneumoniae compared to the results obtained by Etest. All discrepant results were tested by BMD and these were concordant with results obtained by Etest. The MicroScan automated system does not seem to be very efficient for the screening of polymyxin-resistant isolates once an inappropriate sensitivity is achieved. The results presented here show the need for confirmation of the susceptibility profile by use of a dilution method (Etest or BMD).

Comparison of high-pressure liquid chromatography and microbiological assay for determination of ciprofloxacin tablets in human plasma employed in bioequivalence and pharmacokinetics study.

Ciprofloxacin was given orally to 28 healthy male volunteers for single oral dose of 500mg; Plasma samples were collected at different time's interval between 0 and 12h and analyzed both by high pressure liquid chromatography and by a microbiological assay. The detection limits (LOD) were 0.02µg/ml and 0.1µg/ml, for both methods respectively. For each method, coefficients of variation (R(2)) were 0.9995 and 0.9918 in plasma and limit of quantitation (LOQ).02 and 0.5µg/ml. The Comparison of means maximum concentration 2.68 µg/ml at 1.5 hr for test and 2.43 µg/ml are attain in HPLC method of Reference at 2hrs respectively. The plasma concentrations measured by microbiological assay of reference tablet are 3.95µg/ml (mean ± SE) at 1 hour and 3.80µg/ml (mean ± SE) at 1 hour. The concentrations in plasma measured by microbiological method were markedly higher than the high-pressure liquid chromatography values which indicates the presence of antimicrobially active metabolites. The mean ± SE values of pharmacokinetic parameters calculated by HPLC method, for total area under the curve (AUC 0-oo) were 13.11, and 11.91 h.mg/l for both test and reference tablets respectively. The mean ± SE values of clearance measured in l/h were 44.91 and 48.42 respectively. The elimination rate constant Kel [l/h] showed 0.17 l/h for test and 0.15 l/h reference tablets and likewise, absorption half-life expressed in hours shown 0.67 h for test and 1.04 h for reference respectively. The Mean Residence Time for test is 5.48 h and 5.49 h for reference. The mean ± SE values of pharmacokinetic parameters (Microbiological assay) for total area under the curve (AUC 0-oo) were 22.11 and 19.33 h.mg/l for both test and reference tablets respectively. The mean ± SE values of clearance measured in l/h were 29.02 and 31.63 respectively. The elimination rate constant Kel [l/h] showed 0.21 l/h for test and 0.20 l/h reference tablets and likewise, absorption half-life expressed in hours shown 0.86h for test and 0.56 h for reference respectively. The Mean Residence Time for test is 5.27 h and 4.67 h for reference. Significant difference observed between two methods.

Antimicrobial activities of three species of family mimosaceae.

The antimicrobial activities of crude methanolic extract of leaves of Acacia nilotica L., Albizia lebbeck L. and Mimosa himalayana Gamble belonging to family mimosaceae were investigated in this research work. Antibacterial activity was studied by agar well diffusion method against one gram-positive Bacillus subtilis and three gram-negative Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumonia. Crude extract of all plants showed best activity against gram-negative bacterial strains while minor inhibition zones were found against gram positive bacterial strains. Antifungal activity of crude plant extract was screened by agar tube dilution method against Aspergillus nigar and Aspergillus flavus. These results showed that these plants extracts have potential against bacterias, while against fungi their activity is not much effective.

The antimicrobial activity of essential oils and extracts of some medicinal plants grown in Ash-shoubak region - South of Jordan.

The inhibitory effects of essential oils as well as chloroformic extracts of Thymus vulgaris, Thymus serpyllum, Salvia officinalis and Pimpinella anisum grown in Ash-shoubak region-south of Jordan and their possible individual phytochemical constituents was screened against pathogenic clinical and standard strains of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The bioassay employed was the agar well diffusion method. The essential oils and chloroformic extracts of T. vulgaris and T. serpyllum were the most effective against the tested strains of bacteria. Clinical and standard strains of S .aureus and P. aeruginosa were uninhibited by S. officinalis essential oils. P. aeruginosa tested strains were also resistant to P. anisum essential oils. For almost all bacterial strains, the highest antibacterial effect of oils was obtained with the highest tested dose (15 µl). Chlorformic extracts of S. officinalis showed small activity against standard and clinical E. coli strains and were not effective to inhibit strains of P. aeruginosa and S. aureus. Chloroformic extracts obtained from P. anisum and applied at 300 µg/cm(2) slightly inhibited E. coli, but moderately inhibited S. aureus. It is shown from the results that the antibacterial effects of the individual components varied depending upon their chemical structure, functional groups and configuration as well as doses used. This study showed the beneficial effects of the essential oils of T. serpyllum and T. vulgaris grown in Ash-shoubak in inhibiting the growth of microbes and the implications this could have in pharmacy and food technology.

A description of antimicrobial susceptibility of Streptococcus pneumoniae-Siriraj Hospital, Thailand: 2008.

Streptococcus pneumoniae was isolated from 170 patient specimens at Siriraj Hospital during January-December 2008. Patients were 66% male and ranged in age from 3 months to 94 years (mean +/- SD = 38.2 +/- 31.7). The largest proportion (29.4%) of isolates were from patients older than 60 years, followed by patients aged 2-5 years (20%) and from patients less than 2 years (12.4%). Monthly isolation was highest in December (22 isolates in December compared to the average of 13 isolates of the other months). Antimicrobial susceptibility for eight drugs was determined by the disk diffusion method. Overall, susceptibility was generally high to chloramphenicol (71.8%), linezolid (100%), ofloxacin (93.5%) and vancomycin (100%), but less susceptible to erythromycin (35.3%), penicillin (31.1%), tetracycline (28.8%) and trimethoprim/ sulfamethoxazole (24.1%). Among the 105 (62%) isolates resistant to three or more drugs, the most common resistance pattern was erythromycin-penicillin-tetracycline-trimethoprim/sulfamethoxazole, accounting for 39% of such isolates, followed by chloramphenicol-erythromycin-penicillin-tetracycline- trimethoprim/sulfamethoxazole (29.5%). The minimal inhibitory concentrations (MIC) of penicillin and cefotaxime were determined by broth microdilution. By 2008 CLSI criteria, 92% and 90% of 51 sterile site isolates were penicillin and cefotaxime susceptible, including one of two meningitis cases. In contrast, of 26 non-sterile site isolates, only 26.9% and 76.9% were susceptible to penicillin and cefotaxime, respectively. The MICs of penicillin were higher for isolates from non-sterile sites than for those from sterile sites.

Low beta-lactamase-negative ampicillin-resistant Haemophilus influenzae strains are best detected by testing amoxicillin susceptibility by the broth microdilution method.

Ampicillin resistance in Haemophilus influenzae due to alterations in penicillin-binding proteins (beta-lactamase negative ampicillin resistant [BLNAR]) is acquiring increasing clinical and epidemiological importance. BLNAR strains with low ampicillin MICs (0.5 to 4 microg/ml) represent the majority of this population in Europe and the United States, but separating them from susceptible isolates is challenging. To investigate the best method to identify low-BLNAR strains, we studied the antibiotic susceptibilities of 94 clinical isolates of H. influenzae by microdilution, Etest, and disk diffusion: 25 had no resistance mechanisms (gBLNAS), 34 had mutations in the ftsI gene only (gBLNAR), 20 were beta-lactamase producers only (gBLPAR), and 15 showed beta-lactamase production and mutations in the ftsI gene (gBLPACR). By current CLSI breakpoints, most gBLNAR isolates were ampicillin susceptible by microdilution (76.5%) or by Etest (88.2%). Most gBLNAR strains (79.4%) were nonsusceptible to amoxicillin (the most widely used community antibiotic in the United States and Europe) when tested by microdilution. By Etest, 15% of beta-lactamase-positive isolates were nonresistant to ampicillin or amoxicillin. The poorest agreement between Etest and microdilution results was for the gBLPAR isolates (25% for ampicillin, 15% for amoxicillin, and 10% for cefaclor). Low-strength disks of ampicillin and amoxicillin-clavulanic acid poorly identified low-BLNAR isolates and are not recommended as a screening method. We suggest new amoxicillin breakpoints for BLNAR isolates as follows: susceptible, MIC < or = 0.5 microg/ml (no resistance mechanisms; pharmacokinetic/pharmacodynamic [PK/PD] data favorable); intermediate, MICs = 1 to 2 microg/ml (resistance mechanisms present but PK/PD data favorable), and resistant, MICs > or = 4 microg/ml (resistance mechanisms present and PK/PD data unfavorable).