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Vitro Susceptibility (vitro + susceptibility)

Distribution by Scientific Domains

Medical Sciences	88%

Selected Abstracts

Determination of the In Vitro Susceptibility of Feline Tritrichomonas foetus to 5 Antimicrobial Agents

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2007
Elizabeth J. Kather
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 ±80 ,g/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 ,g/mL) and concentrations of 1.25 and 2.5 ,g/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. [source]

Multiple transporters associated with malaria parasite responses to chloroquine and quinine

MOLECULAR MICROBIOLOGY, Issue 4 2003
Jianbing Mu
Summary Mutations and/or overexpression of various transporters are known to confer drug resistance in a variety of organisms. In the malaria parasite Plasmodium falciparum, a homologue of P-glycoprotein, PfMDR1, has been implicated in responses to chloroquine (CQ), quinine (QN) and other drugs, and a putative transporter, PfCRT, was recently demonstrated to be the key molecule in CQ resistance. However, other unknown molecules are probably involved, as different parasite clones carrying the same pfcrt and pfmdr1 alleles show a wide range of quantitative responses to CQ and QN. Such molecules may contribute to increasing incidences of QN treatment failure, the molecular basis of which is not understood. To identify additional genes involved in parasite CQ and QN responses, we assayed the in vitro susceptibilities of 97 culture-adapted cloned isolates to CQ and QN and searched for single nucleotide polymorphisms (SNPs) in DNA encoding 49 putative transporters (total 113 kb) and in 39 housekeeping genes that acted as negative controls. SNPs in 11 of the putative transporter genes, including pfcrt and pfmdr1, showed significant associations with decreased sensitivity to CQ and/or QN in P. falciparum. Significant linkage disequilibria within and between these genes were also detected, suggesting interactions among the transporter genes. This study provides specific leads for better understanding of complex drug resistances in malaria parasites. [source]

The activity of meropenem and comparators against Acinetobacter strains isolated from European hospitals, 1997,2000

CLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2003
P. J. Turner
In vitro susceptibilities to meropenem and comparators of Acinetobacter strains isolated from serious infections in 37 European hospital centers participating in the Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program (1997,2000) were tested. There were 635 Acinetobacter strains collected: 490 A. baumannii; 51 A. calcoaceticus var. lwoffii; and 94 other Acinetobacter strains. Overall, meropenem and imipenem were the most effective agents tested. Resistance to the antimicrobials was: 14%, meropenem; 16%, imipenem; 39%, piperacillin,tazobactam; 41%, tobramycin; 45%, ceftazidime; and 53%, ciprofloxacin. Thus, the carbapenems have useful activity against Acinetobacter spp. and represent a viable choice for treating infections caused by these organisms. [source]

Determination of the In Vitro Susceptibility of Feline Tritrichomonas foetus to 5 Antimicrobial Agents

Blastomycosis-like pyoderma: Successful treatment with low-dose acitretin

AUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 2 2005
Roland TD Nguyen
SUMMARY Blastomycosis-like pyoderma typically presents as verrucous plaque(s) with a purulent discharge through multiple sinuses. Two patients with blastomycosis-like pyoderma developing on significantly sun-damaged skin are presented: an 84-year-old man with multiple painful nodules and plaques, and a 92-year-old woman with a solitary plaque on the left calf. Histopathology showed pseudoepitheliomatous hyperplasia with dermal foci of suppuration. Staphylococcus aureus was isolated from a biopsy specimen in the first patient, whereas the latter patient had Prevotella and Corynebacterium species. Investigations for fungi and mycobacteria yielded negative results. These microbiological findings further supported the clinicopathological diagnosis. Both patients failed to respond to oral doxycycline despite the in vitro susceptibility of the organisms. Treatment with low-dose oral acitretin was successful in both patients after 3,4 months. [source]

In vitro susceptibility of the seven Malassezia species to ketoconazole, voriconazole, itraconazole and terbinafine

BRITISH JOURNAL OF DERMATOLOGY, Issue 4 2000
A.K. Gupta
Fifty-five strains, either authentic or ex-type, of seven Malassezia species were investigated for in vitro susceptibility to various concentrations (0·03,64·0 µg/mL) of three azole drugs, ketoconazole, voriconazole and itraconazole, as well as the allylamine terbinafine, using the agar dilution method. All strains of the seven Malassezia species were susceptible to the three azole drugs at low concentrations. M. furfur, M. sympodialis, M. slooffiae, M. pachydermatis, M. globosa, M. obtusa and M. restricta were most sensitive to ketoconazole and itraconazole, with minimum inhibitory concentrations (MICs) ranging from , 0·03 to 0·125 ,g/mL. The recently introduced antifungal, voriconazole, was also very effective, with MIC80 values , 0·03 ,g/mL for 80% of strains. MICs of terbinafine against the seven Malassezia species ranged from , 0·03 to 64·0 ,g/mL. There were variations in susceptibility of the seven Malassezia species to ketoconazole, voriconazole, itraconazole and terbinafine. Strains of M. furfur, M. globosa and M. obtusa were more tolerant to terbinafine than the remaining Malassezia species; M. sympodialis was highly susceptible. M. furfur strains tested with terbinafine ranged from highly susceptible to relatively resistant. Correct identification of Malassezia species could facilitate selection of appropriate antifungal therapy. [source]

In vitro susceptibility to 17 antimicrobials of clinical Clostridium difficile isolates collected in 1993,2007 in Sweden

CLINICAL MICROBIOLOGY AND INFECTION, Issue 8 2010
T. Norén
Clin Microbiol Infect 2010; 16: 1104,1110 Abstract This study investigated the MICs of 17 antimicrobials, for 606 toxigenic clinical isolates of Clostridium difficile collected between 1993 and 2007 in Sweden. Low MIC90 values were found for metronidazole (0.5 mg/L), vancomycin (1.0 mg/L), teicoplanin (0.125 mg/L), fusidic acid (1.0 mg/L), linezolid (2.0 mg/L), daptomycin (2.0 mg/L) and tigecycline (0.064 mg/L). Three isolates (0.5%) had elevated MICs for vancomycin (4,8 mg/L); however, these isolates originated from the same patient, who was receiving long-term intravenous vancomycin treatment. High-level clindamycin resistant isolates (MIC >256 mg/L) peaked in 1997 with 39 of 95 (41%) and out of these, 36% were also highly resistant to erythromycin. ,-Lactams such as penicillin V and piperacillin displayed MIC90s of 8 and 32 mg/L, respectively, whereas MICs of cefuroxime were >256 mg/L for all isolates. Universal resistance to ciprofloxacin and levofloxacin was found, and resistance to moxifloxacin increased from 4% of isolates in 2004 to 23% in 2007. Notably, these moxifloxacin-resistant isolates did not belong to the recent epidemic PCR ribotype 027, but to the pre-existing epidemic type 012 (82%), and these isolates accounted for the majority of isolates that were resistant to clindamycin (70%), tetracycline (84%) and rifampicin (92%) as well. This investigation of susceptibility data on clinical C. difficile isolates showed variations of multiresistance to be due to a specific PCR ribotype 012, emphasizing the importance of genotyping when evaluating emerging resistance over time. [source]

In vitro susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis: a European multicenter study during 2000,2001

CLINICAL MICROBIOLOGY AND INFECTION, Issue 7 2003
M. E. Jones
Objective, To assess the current (2001) activity of respiratory fluoroquinolones and comparator agents against respiratory pathogens isolated in European countries. Methods, During 2000,2001, we prospectively collected 1995 isolates of Haemophilus influenzae, 1870 isolates of Streptococcus pneumoniae and 649 isolates of Moraxella catarrhalis from hospital laboratories in France, Germany, Greece, Italy, Spain and the UK. National Committee for Clinical Laboratory Standards (NCCLS)-approved broth microdilution antimicrobial susceptibility testing methods and interpretive criteria were used throughout. Results, Of the S. pneumoniae isolates, 99.6% were susceptible to moxifloxacin, gatifloxacin and levofloxacin; the corresponding figure for H. influenzae was 100%. All M. catarrhalis isolates had moxifloxacin MICs ,,0.12 mg/L. For all three pathogens, fluoroquinolone susceptibility remained unchanged from the previous 1997,98 study. The incidence of penicillin non-susceptibility in the S. pneumoniae isolates tested remained similar to or higher than that recorded in previous studies: France, 165/291 (56.7%); Germany, 46/506 (9.1%); Greece, 20/55 (36.4%); Italy, 45/364 (12.4%); Spain, 146/268 (54.5%); and the UK, 26/386 (6.7%). Significant levels of resistance to oral compounds (cefuroxime, cefaclor, cefdinir, clarithromycin, azithromycin, tetracycline, and trimethoprim,sulfamethoxazole) were detected among S. pneumoniae isolates. ,-Lactamase production among H. influenzae isolates ranged from 6.2% to 33.1% per country, and ampicillin, clarithromycin or trimethoprim,sulfamethoxazole resistance were the most common phenotypes detected. ,-Lactamase production among M. catarrhalis isolates ranged from 94.1% to 100% per country. Conclusions, With the exception of a few localized reports, resistance to moxifloxacin and other new fluoroquinolones in common respiratory pathogens is a rare occurrence, despite significant resistance to other compound classes. Surveillance will play a key role in tracking changes in fluoroquinolone susceptibility in European countries. [source]