scholarly journals In Vitro Antimicrobial Susceptibility Testing of Bacterial Enteropathogens Causing Traveler's Diarrhea in Four Geographic Regions

2001 ◽  
Vol 45 (1) ◽  
pp. 212-216 ◽  
Author(s):  
Harumi Gomi ◽  
Zhi-Dong Jiang ◽  
Javier A. Adachi ◽  
David Ashley ◽  
Brett Lowe ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Moderate Activity ◽  
Traveler’S Diarrhea ◽  
The World ◽  
Traveler's Diarrhea ◽  
Susceptibility Patterns

ABSTRACT The emergence of resistant enteropathogens has been reported worldwide. Few data are available on the contemporary in vitro activities of commonly used antimicrobial agents against enteropathogens causing traveler's diarrhea (TD). The susceptibility patterns of antimicrobial agents currently available or under evaluation against pathogens causing TD in four different areas of the world were evaluated. Pathogens were identified in stool samples from U.S., Canadian, or European adults (18 years of age or older) with TD during 1997, visiting India, Mexico, Jamaica, or Kenya. MICs of 11different antimicrobials were determined against 284 bacterial enteropathogens by the agar dilution method. Ciprofloxacin, levofloxacin, ceftriaxone, and azithromycin were highly active in vitro against the enteropathogens, while traditional antimicrobials such as ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole showed high levels and high frequencies of resistance. Rifaximin, a promising and poorly absorbable drug, had an MIC at which 90% of the strains tested were inhibited of 32 μg/ml, 250 times lower than the concentration of this drug in the stools. Amdinocillin, nalidixic acid, and doxycycline showed moderate activity. Fluoroquinolones are still the drugs of choice for TD in most regions of the world, although our study has a limitation due to the lack of Escherichia coli samples from Kenya and possible bias in selection of the patients for evaluation. Azithromycin and rifaximin should be considered as promising new agents. The widespread in vitro resistance of the traditional antimicrobial agents reported since the 1980s and the new finding of resistance to fluoroquinolones in Southeast Asia are the main reasons for monitoring carefully the antimicrobial susceptibility patterns worldwide and for developing and evaluating new antimicrobial agents for the treatment of TD.

scholarly journals Antimicrobial Susceptibility of Invasive Streptococcus pneumoniae Isolates in Portugal over an 11-Year Period

2006 ◽  
Vol 50 (6) ◽  
pp. 2098-2105 ◽  
Author(s):  
Ricardo Dias ◽  
Deolinda Louro ◽  
Manuela Caniça
Keyword(s):  
Multidrug Resistance ◽  
Streptococcus Pneumoniae ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Invasive Disease ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
National Surveillance ◽  
Agar Dilution

ABSTRACT This national surveillance study presents the in vitro activities of the main antimicrobial agents against 1,331 S. pneumoniae isolates as tested by an agar dilution method according to the guidelines of the Clinical and Laboratory Standards Institute (formerly NCCLS). The strains were isolated in several regions of Portugal from cases of invasive disease over an 11-year period (1994 to 2004). This study shows that the percentage of penicillin-nonsusceptible strains increased from 12% in 1994 to 28.5% in 2000. Then the rate declined to 17.7% in 2003 but increased again to 23.2% in 2004. Nevertheless, the rate of highly resistant isolates declined consistently, to 0.9% in 2001 to 2004. Ceftriaxone- and cefotaxime-nonsusceptible isolates became less frequent, from 4% and 8%, respectively, in 1994 to ≤1% in 2004. The macrolide-lincosamide-streptogramin B phenotype was the predominant macrolide phenotype found. The increase in the percentage of isolates that were only nonsusceptible to erythromycin (3.7% in 1994 to 1998 to 9.1% in 2002 to 2004) was similar to that for isolates with coresistance to penicillin and erythromycin (3.3% in 1994 to 1998 to 9.1% in 2002 to 2004). The nonsusceptibility to ciprofloxacin increased during recent years, from 0.5% in 2002 to 3.5% in 2004. Multidrug resistance also increased in recent years: from 7.9% in 2002 to 15.6% in 2004. The increasing use of macrolides could be causing the increase in penicillin and multidrug resistance, due to the coresistance to macrolides. The use of penicillin to treat empirical invasive pneumococci infections may need to be reconsidered.

scholarly journals Antimicrobial susceptibility patterns of some recently established coryneform bacteria.

1996 ◽  
Vol 40 (12) ◽  
pp. 2874-2878 ◽  
Author(s):  
G Funke ◽  
V Pünter ◽  
A von Graevenitz
Keyword(s):  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Glycopeptide Antibiotics ◽  
Coryneform Bacteria ◽  
Corynebacterium Glucuronolyticum ◽  
Agar Dilution ◽  
Susceptibility Patterns

The susceptibility patterns of 480 isolates representing six recently defined species of coryneform bacteria (Corynebacterium amycolatum [n = 101], Corynebacterium auris [n = 48], Corynebacterium glucuronolyticum [n = 86], Brevibacterium casei [n = 50], Dermabacter hominis [n = 49], and Turicella otitidis [n = 146]) to 17 antimicrobial agents were determined by an agar dilution method. Most significantly, for C. amycolatum strains the MICs at which 90% of isolates are inhibited were > or = 32 micrograms/ml for nearly all agents. However, all 480 strains examined were susceptible to glycopeptide antibiotics.

scholarly journals Telithromycin- and Fluoroquinolone-Resistant Streptococcus pneumoniae in Taiwan with High Prevalence of Resistance to Macrolides and β-Lactams: SMART Program 2001 Data

2003 ◽  
Vol 47 (7) ◽  
pp. 2145-2151 ◽  
Author(s):  
Po-Ren Hsueh ◽  
Lee-Jene Teng ◽  
Tsu-Lan Wu ◽  
Dine Yang ◽  
Wen-Kuei Huang ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Random Amplified Polymorphic Dna ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Time Period ◽  
High Prevalence ◽  
Agar Dilution ◽  
Different Parts

ABSTRACT There is a high prevalence of β-lactam- and macrolide-resistant Streptococcus pneumoniae in Taiwan. To understand the in vitro susceptibilities of recent isolates of S. pneumoniae to fluoroquinolones and telithromycin (which is not available in Taiwan), the MICs of 23 antimicrobial agents for 936 clinical isolates of S. pneumoniae isolated from different parts of Taiwan from 2000 to 2001 were determined by the agar dilution method. Overall, 72% of isolates were not susceptible to penicillin (with 61% being intermediate and 11% being resistant) and 92% were resistant to erythromycin. Telithromycin MICs were ≥1 μg/ml for 16% of the isolates, and for 99% of these isolates the MICs of all macrolides tested were ≥256 μg/ml; all of these isolates had the constitutive macrolide-lincosamide-streptogramin B phenotype. Eighty-eight percent of the isolates were resistant to three or more classes of drugs. The ciprofloxacin MICs were ≥4 μg/ml for six (0.6%) isolates from five patients collected in 2000 and 2001, and the levofloxacin MICs were ≥8 μg/ml for five of these isolates. Seven isolates for which ciprofloxacin MICs were ≥4 μg/ml, including one isolate recovered in 1999, belonged to three serotypes (serotype 19F, five isolates; serotype 23A, one isolate; and serotype 23B, one isolate). The isolates from the six patients for which ciprofloxacin MICs were ≥4 μg/ml had different pulsed-field gel electrophoresis profiles and random amplified polymorphic DNA patterns, indicating that no clonal dissemination occurred over this time period. Despite the increased rate of fluoroquinolone use, the proportion of pneumococcal isolates for which ciprofloxacin MICs were elevated (≥4 μg/ml) remained low. However, the occurrence of telithromycin resistance is impressive and raises concerns for the future.

scholarly journals In Vitro Antimicrobial Susceptibility Testing of Helicobacter felis, H. bizzozeronii, and H. salomonis

2005 ◽  
Vol 49 (7) ◽  
pp. 2997-3000 ◽  
Author(s):  
K. Van den Bulck ◽  
A. Decostere ◽  
I. Gruntar ◽  
M. Baele ◽  
B. Krt ◽  
...  
Keyword(s):  
Antimicrobial Agent ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Acquired Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Helicobacter Felis ◽  
Agar Dilution

ABSTRACT The susceptibilities of Helicobacter felis (15 strains), H. bizzozeronii (7 strains), and H. salomonis (3 strains) to 10 antimicrobial agents were investigated by determination of the MIC using the agar dilution method. No consistent differences were noticed between the different Helicobacter species, which were all highly susceptible to ampicillin, clarithromycin, tetracycline, tylosin, enrofloxacin, gentamicin, and neomycin, as demonstrated by low MICs. Higher MICs were obtained for lincomycin (up to 8 μg/ml) and spectinomycin (up to 4 μg/ml). Two H. felis strains showed a MIC of 16 μg/ml for metronidazole, suggesting acquired resistance to this antimicrobial agent.

scholarly journals Antimicrobial Susceptibilities of Campylobacter Strains Isolated from Finnish Subjects Infected Domestically or from Those Infected Abroad

2003 ◽  
Vol 47 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Hilpi Rautelin ◽  
Antti Vierikko ◽  
Marja-Liisa Hänninen ◽  
Martti Vaara
Keyword(s):  
Campylobacter Jejuni ◽  
Antimicrobial Agents ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Campylobacter Coli ◽  
Antimicrobial Susceptibilities ◽  
Agar Dilution ◽  
Stool Samples

ABSTRACT The in vitro susceptibilities of 678 Campylobacter jejuni and Campylobacter coli strains isolated from stool samples of the same number of Finnish subjects were studied. A total of 523 patients, representing inhabitants from throughout Finland, had not traveled abroad within the 2 weeks prior to becoming ill, whereas 155 persons had presumably acquired their infections abroad. The antimicrobial agents studied were erythromycin, ciprofloxacin, levofloxacin, trovafloxacin, and moxifloxacin. The MICs of these antimicrobial agents were determined by the agar dilution method. The growth of all domestic isolates was inhibited by erythromycin at concentrations of 4 μg/ml, and for these isolates the fluoroquinolone MICs at which 90% of isolates are inhibited (MIC90s) ranged from 0.06 to 0.5 μg/ml. For the foreign isolates, the erythromycin MIC90 was still low (4 μg/ml), but their susceptibilities to fluoroquinolones were clearly reduced (MIC90s, 8 to 64 μg/ml). Of the four different fluoroquinolones studied, ciprofloxacin was the least active (MIC90, 64 μg/ml).

Computer-aided structural optimization, synthesis, evaluation of the antimicrobial and cytotoxic activity of some pyrazoline derivatives

MedPharmRes ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 33-39
Author(s):  
Tai Duc Nguyen ◽  
Du Nguyen Hai Ly ◽  
Thi Hong Tuoi Do ◽  
Phuong Thi Ngoc Huynh
Keyword(s):  
Antimicrobial Activity ◽  
Anticancer Activity ◽  
Antibacterial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Moderate Activity ◽  
Docking Model ◽  
Ic50 Values ◽  
Relationship Of

Introduction: In the last few decades, pyrazoline-based substances have emerged as potential antimicrobial and anticancer candidates. In concern with antimicrobial activity, this study aims to build a docking model to predict the structure of potential 2-pyrazoline derivatives. The cytotoxicity of some compounds was also evaluated to get insight into the structure–anticancer activity relationship of the 2-pyrazoline derivatives. Methods: Docking models were built on virtual FabH enzymes using FlexX platform with 2-pyrazoline derivatives served as test sets. Afterward, derivatives with high docking scores were chemically synthesized and evaluated for antibacterial activity using the agar dilution method. Furthermore, MTT assay was used to assess the cytotoxicity of these compounds. Results: The docking score and the in vitro minimum inhibitory concentration (MIC) value on Staphylococcus aureus (S. aureus) bacteria strongly correlate with an R-square value of 0.6751 (p < 0.0001). Four 2 pyrazoline derivatives were synthesized and evaluated for antimicrobial activity. Their MIC values on S. aureus range between 4 and 16 μg/mL, consistent with ones predicted by the docking model. Apropos cytotoxic properties, a series of 2-pyrazolines exhibit a moderate activity on HepG2, RD, and MDA-MB-231. The most active compound, HP10, has the IC50 values on these cell lines. which are 26.62 μM, 17.74 μM, 14.47 μM, respectively. Conclusion: Our research built a docking model on the virtual S. aureus FabH enzyme with high potential in predicting antibacterial activities of different 2-pyrazoline derivatives. Moreover, our cytotoxicity results provided data for further studies on the anticancer activity of these promising derivatives.

scholarly journals In Vitro Activities of 15 Antimicrobial Agents against 110 Toxigenic Clostridium difficile Clinical Isolates Collected from 1983 to 2004

2007 ◽  
Vol 51 (8) ◽  
pp. 2716-2719 ◽  
Author(s):  
David W. Hecht ◽  
Minerva A. Galang ◽  
Susan P. Sambol ◽  
James R. Osmolski ◽  
Stuart Johnson ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Antimicrobial Agents ◽  
Treatment Strategies ◽  
The United States ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
In Vitro Susceptibility ◽  
Agar Dilution

ABSTRACT The incidence and severity of Clostridium difficile-associated disease (CDAD) is increasing, and standard treatment is not always effective. Therefore, more-effective antimicrobial agents and treatment strategies are needed. We used the agar dilution method to determine the in vitro susceptibility of the following antimicrobials against 110 toxigenic clinical isolates of C. difficile from 1983 to 2004, primarily from the United States: doripenem, meropenem, gatifloxacin, levofloxacin, moxifloxacin, OPT-80, ramoplanin, rifalazil, rifaximin, nitazoxanide, tizoxanide, tigecycline, vancomycin, tinidazole, and metronidazole. Included among the isolates tested were six strains of the toxinotype III, NAP1/BI/027 group implicated in recent U.S., Canadian, and European outbreaks. The most active agents in vitro were rifaximin, rifalazil, tizoxanide, nitazoxanide, and OPT-80 with MICs at which 50% of the isolates are inhibited (MIC50) and MIC90 values of 0.0075 and 0.015 μg/ml, 0.0075 and 0.03 μg/ml, 0.06 and 0.125 μg/ml, 0.06 and 0.125 μg/ml, 0.125 and 0.125 μg/ml, respectively. However, for three isolates the rifalazil and rifaximin MICs were very high (MIC of >256 μg/ml). Ramoplanin, vancomycin, doripenem, and meropenem were also very active in vitro with narrow MIC50 and MIC90 ranges. None of the isolates were resistant to metronidazole, the only agent for which there are breakpoints, with tinidazole showing nearly identical results. These in vitro susceptibility results are encouraging and support continued evaluation of selected antimicrobials in clinical trials of treatment for CDAD.

Effect of Carbon Dioxide on Testing of Susceptibilities of Respiratory Tract Pathogens to Macrolide and Azalide Antimicrobial Agents

1999 ◽  
Vol 43 (8) ◽  
pp. 1862-1865 ◽  
Author(s):  
M. M. Johnson ◽  
S. L. Hill ◽  
Laura J. V. Piddock
Keyword(s):  
Carbon Dioxide ◽  
Respiratory Tract ◽  
Antimicrobial Agents ◽  
Ph Effect ◽  
Significant Loss ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Chronic Obstructive ◽  
Activity Effect

ABSTRACT The in vitro activities of erythromycin, azithromycin, and clarithromycin against 178 clinical isolates from the lower respiratory tract of patients with chronic obstructive pulmonary disease were determined by an agar dilution method. The plates were incubated in air alone or in 5% carbon dioxide. The MICs measured in air alone were lower for most isolates than those measured in 5% carbon dioxide, illustrating the “pH effect” of incubation in carbon dioxide. Testing of isolates in 5% carbon dioxide on pH-adjusted medium (pH 8.4) resulted in MICs of one or two doubling dilutions lower than those obtained on agar with a neutral pH. A bioassay of the three agents incubated in air and in 5% carbon dioxide resulted in a significant loss of activity of all three agents in the carbon dioxide-enriched atmosphere. However, this loss-of-activity effect was significantly reduced when the bioassay medium was adjusted to pH 8.4 prior to incubation in 5% carbon dioxide.

scholarly journals In Vitro Antimicrobial Susceptibility Profiles of Gram-Positive Anaerobic Cocci Responsible for Human Invasive Infections

2021 ◽  
Vol 9 (8) ◽  
pp. 1665
Author(s):  
François Guérin ◽  
Loren Dejoies ◽  
Nicolas Degand ◽  
Hélène Guet-Revillet ◽  
Frédéric Janvier ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
In Vitro Susceptibility ◽  
Parvimonas Micra ◽  
Invasive Infections ◽  
Anaerobic Infections ◽  
Susceptibility Profiles

The aim of this multicentre study was to determine the in vitro susceptibility to anti-anaerobic antibiotics of Gram-positive anaerobic cocci (GPAC) isolates responsible for invasive infections in humans. A total of 133 GPAC isolates were collected in nine French hospitals from 2016 to 2020. All strains were identified to the species level (MALDI-TOF mass spectrometry, 16S rRNA sequencing). Minimum inhibitory concentrations (MICs) of amoxicillin, piperacillin, cefotaxime, imipenem, clindamycin, vancomycin, linezolid, moxifloxacin, rifampicin, and metronidazole were determined by the reference agar dilution method. Main erm-like genes were detected by PCR. The 133 GPAC isolates were identified as follows: 10 Anaerococcus spp., 49 Finegoldia magna, 33 Parvimonas micra, 30 Peptoniphilus spp., and 11 Peptostreptococcus anaerobius. All isolates were susceptible to imipenem, vancomycin (except 3 P. micra), linezolid and metronidazole. All isolates were susceptible to amoxicillin and piperacillin, except for P. anaerobius (54% and 45% susceptibility only, respectively). MICs of cefotaxime widely varied while activity of rifampicin, and moxifloxacin was also variable. Concerning clindamycin, 31 were categorized as resistant (22 erm(A) subclass erm(TR), 7 erm(B), 1 both genes and 1 negative for tested erm genes) with MICs from 8 to >32 mg/L. Although GPACs are usually susceptible to drugs commonly used for the treatment of anaerobic infections, antimicrobial susceptibility should be evaluated in vitro.

scholarly journals In Vitro Activities of Ceftobiprole, Tigecycline, Daptomycin, and 19 Other Antimicrobials against Methicillin-Resistant Staphylococcus aureus Strains from a National Survey of Belgian Hospitals

2006 ◽  
Vol 50 (8) ◽  
pp. 2680-2685 ◽  
Author(s):  
Olivier Denis ◽  
Ariane Deplano ◽  
Claire Nonhoff ◽  
Marie Hallin ◽  
Raf De Ryck ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Therapeutic Potential ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Methicillin Resistant ◽  
Excellent Activity ◽  
Agar Dilution

ABSTRACT The in vitro activities of 22 antimicrobial agents, including ceftobiprole, daptomycin, and tigecycline, against 511 methicillin-resistant Staphylococcus aureus (MRSA) isolates from 112 Belgian hospitals were studied by using the CLSI agar dilution method. Isolates were characterized by pulsed-field gel electrophoresis (PFGE) analysis and by PCR detection of determinants of resistance to aminoglycosides, macrolides-lincosamides-streptogramins, and tetracyclines. A representative set of isolates with different PFGE genotypes was further characterized by multilocus sequence typing, determination of staphylococcal cassette chromosome mec (SCCmec) type, and multiplex PCR for toxic shock syndrome type 1 (TSST-1) and Panton-Valentine leukocidin genes. MRSA isolates belonged to nine epidemic MRSA clones, of which sequence type 45 (ST45)-SCCmec IV and ST8-SCCmec IV were predominant, accounting for 49 and 20% of isolates, respectively. The distribution of antimicrobial resistance and TSST-1 genes was strongly linked to clonal types. Ceftobiprole, daptomycin, and tigecycline showed high activity against all isolates of these sporadic and epidemic MRSA clones, as indicated by MIC90s of 2 mg/liter, 0.5 mg/liter, and 0.25 mg/liter, respectively. The MIC distribution of daptomycin and tigecycline was not different in isolates with decreased susceptibility to glycopeptides or tetracyclines, respectively. Ceftobiprole MICs were not correlated with oxacillin and cefoxitin MICs. These data indicate excellent activity of the newly developed agents ceftobiprole, daptomycin, and tigecycline against MRSA isolates recently recovered from hospitalized patients in Belgium, supporting their therapeutic potential for nosocomial MRSA infections.

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