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 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 Characterization of Clinical Isolates ofEnterococciwith Special Reference to Glycopeptide Susceptibility at a Tertiary Care Center of Eastern Nepal

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Aasish Karna ◽  
Ratna Baral ◽  
Basudha Khanal
Keyword(s):  
Multidrug Resistance ◽  
Minimum Inhibitory Concentration ◽  
Antimicrobial Susceptibility ◽  
Inhibitory Concentration ◽  
Tertiary Care ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disc Diffusion ◽  
Diffusion Technique ◽  
Agar Dilution

Background. Enterococci, once considered as a harmless commensal of intestine, have now emerged as medically important pathogens and are associated with both community-acquired and nosocomial infections. They bear the potential to exhibit resistance against all commonly used antibiotics either by inherent or acquired mechanism, posing a therapeutic challenge.Objectives. This study aimed to characterize enterococci up to the species level and study their antibiogram with special regard to vancomycin.Methods. A descriptive cross-sectional study was conducted in the Department of Microbiology, B.P. Koirala Institute of Health Sciences, Dharan, Nepal, from February to May 2017. A total of 91 enterococcal isolates recovered from clinical specimens were investigated in this study. Their identification and speciation were done according to standard microbiological guidelines. Kirby–Bauer disc diffusion technique was used to study antimicrobial susceptibility pattern, whereas minimum inhibitory concentration of vancomycin was determined by the agar dilution method, with reference to Clinical and Laboratory Standards Institute guidelines.Results. Seven different species of enterococci were isolated,E. faecalisandE. faeciumaccounting about 45% each. The other species encountered wereE.avium,E.cecorum,E.dispar,E.durans, andE.raffinosus. Highest proportion of antimicrobial susceptibility was recorded for linezolid (97.8%), followed by teicoplanin (95.6%) and high-level gentamicin (81.3%). Sensitivity to vancomycin was seen in 79.1% isolates. Likewise, 82.1% of urinary strains were susceptible to nitrofurantoin. A total of 4 disparities were observed between the disc diffusion technique and agar dilution method in determining vancomycin resistance. Multidrug resistance was observed in 31.9% isolates. The overall prevalence of vancomycin-resistant enterococci based on the standard minimum inhibitory concentration method was 25.3%.Conclusions.Enterococcus faecalisandE. faeciumwere the predominant species in causing enterococcal infections. The alarming rise in prevalence of vancomycin and multidrug resistance strains warrants immediate, adequate, and efficient surveillance program to prevent and control its spread.

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 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).

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.

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 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.

scholarly journals Antimicrobial susceptibility of Campylobacter cuniculorum isolated from rabbits reared in intensive and rural farms

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Silvia Piva ◽  
Daniela Florio ◽  
Domenico Mion ◽  
Renato Giulio Zanoni
Keyword(s):  
Nalidixic Acid ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Inhibitory Concentration ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Pathogenic Role ◽  
Agar Dilution ◽  
Human Campylobacteriosis

The present study aimed to investigate the antimicrobial susceptibility in <em>Campylobacter cuniculorum</em> of 29 isolates on non-selective media from rabbits reared in 18 intensive and 11 rural farms not epidemiologically correlated. Minimum inhibitory concentration (MIC) of 8 antimicrobial agents was determined using the agar dilution method recommended by Clinical and Laboratory Standards Institute (CLSI), modified, for what concern the supplements in the base medium and incubation conditions, for <em>C. cuniculorum</em> isolates. The isolates obtained from rural farming resulted susceptible to all the antimicrobial agents tested, with the exception of one isolate resistant to nalidixic acid. All the isolates obtained from intensively farmed rabbits were sensitive to chloramphenicol and ampicillin; 16 isolates were resistant to tetracycline; 15 to nalidixic acid and erythromycin, 13 and 10 isolates to, ciprofloxacin and enrofloxacin respectively and only 1 to gentamicin. The resistance of several isolates to macrolides and fluoroquinolones, which represent the drugs of choice in treatment of human campylobacteriosis, could pose a risk to human health if a pathogenic role of <em>C. cuniculorum</em> was demonstrated.

Sign in / Sign up

Export Citation Format

Share Document