Phenotypic detection of metallo-beta-lactamase production in clinical isolates of Escherichia coli and Klebsiella pneumoniae in a tertiary care hospital

Introduction: Carbapenem resistance due to metallo-beta-lactamase (MBL)-producing bacteria is an emerging threat worldwide. This study aimed to detect the MBL production in clinical isolates of E. coli and Klebsiella pneumoniae species in our hospital setting and to evaluate the efficiency of two phenotypic methods for the detection of MBL production. Materials and Methods: The present study was carried out in the Department of Microbiology, MGM Medical College and Hospital, Aurangabad, Maharashtra, for a period of 2 years from April 2018 to March 2020. From a total of 12,324 various clinical specimens, 393 isolates of E. coli and Klebsiella pneumoniae species were tested for MBL production. MBL was detected by two different phenotypic methods, i.e., combined disc test and E-test. Results: Out of 393 isolates, 130 (33.07%) isolates were resistant to imipenem on screening of which 71 (18.06%) were Klebsiella pneumoniae and 59 (15.01%) were E. coli. About 43.66% Klebsiella pneumoniae isolates and 40.67% E. coli isolates were MBL-positive by the combined disc test. Using the E-test, MBL production was found to be 46.47% and 45.76% in Klebsiella pneumoniae and E. coli, respectively. Conclusion: Routine screening of MBL-producing organisms should be performed in diagnostic laboratories to control the spread of resistance and for the proper management of antibiotic therapy. E-test is better than the combined disc test for the detection of MBL-producing gram-negative bacilli.

Bacteriemia por Staphylococcus aureus con sensibilidad disminuida heterogénea a vancomicina: reporte de un caso / Staphylococcus aureus bacteremia with heterogeneous intermediate-level vancomycin resistance: a case report

Staphylococcus aureusmeticilina-resistente (SAMR)es una causa frecuente de bacteriemias intrahospitalarias. Para su tratamiento se utiliza vancomicina y han emergido cepas con sensibilidad disminuida heterogénea (h-VISA) que albergan subpoblaciones con sensibi-lidad reducida a vancomicina. Se comunica un caso de bacteriemia intra-tratamiento con vancomicina por SAMR h-VISA. El aislamiento muestra sensibilidad a vancomicina (CIMvan: 1 µg/mL), sin embargo E-test GRD sugiere h-VISA (CIMvan: 2 µg/mL y CIMtei: 8 µg/mL). El análisis del perfil poblacional - área bajo la curva (PAP-AUC) valida este hallazgo. Se rota a linezolid con resolución clínica.

Methicillin-resistant Staphylococcus aureus (SAMR) is a common cause of nosocomial bacteremia. Vancomycin, a glycopeptide, is widely employed for the therapy of SAMR infections. In recent years, heterogeneous vancomycin-intermediate strains (h-VISA) have emerged. We report a case of intra-treatment bacteremia caused by SAMR h-VISA. The isolate shows susceptibility to vancomycin (MICvan: 1 µg/mL). But the GRD E-test suggests h-VISA (MICvan: 2 µg/mL and MICtei: 8 µg/mL). The population analysis profile - area under the curve (PAP-AUC) validates SAMR h-VISA. Rotation of antibiotic therapy with linezolid is done, with good clinical outcome.

Isolation, identification and antifungal susceptibility of Candida in patients with fungal sepsis

Background: In this study, our aim was to identify and isolate Candida species from patients admitted in ICU,s of our hospital and to determine their susceptibilities to various antifungal agents so as to find the local resistance pattern and guide for empirical treatment.Methods: In our study 37 strains of candida were isolated (4 Candida albicans, 33 Non-albicans Candida strains). Candida species were identified by conventional, biochemical and molecular methods. Antifungal susceptibility tests for amphotericin B, fluconazole, itraconazole, ketoconazole and voriconazole were performed with broth microdilution method and E- tests as described by National Committee for Clinical Laboratory Standards (NCCLS).Results: Out of 37 Candida strains, the most prevalent species were C. tropicalis (43.2%), C. parapsilosis (24.3%), C. krusei (16.2%), C. albicans (10.8%), and C. glabrata (2.7%). Among all strains four strains (10.8 %) were resistant, two Candida albicans where found resistant to fluconazole one Candida krusei and one Candida parapsilosis were found to be resistant to all azoles.Conclusions: Candidemia continues to be associated with substantial morbidity and mortality and non albicans Candida species are the commonly isolated pathogen from those patients admitted in tertiary care hospitals in Indian scenario. Thus, it is imperative to perform antifungal susceptibility to select appropriate and effective antifungal therapy.

Evaluation on the Accuracy of VITEK 2 Compact for the Susceptibility of Carbapenem-Resistant Klebsiella Peumoniae to Amikacin / 现代检验医学杂志

Objective To evaluate the accuracy of VITEK 2 Compact in the detection of the drug susceptibility of carbapenemresistant Klebsiella pneumoniae (CRKP) to Amikacin.Methods The susceptibility for 147 isolates of SRKP to Amikacin were detected by VITEK 2 Compact,disk diffusion method (K-B method) and E-test method,respectively.Results Among the 147 strains of Klebsiella pneumoniae,the drug susceptibility results were consistent between K B and E-test method.Among the 5 strains,the results were totally consistent by VITEK 2 Compact,K-B method and E test method,of which 4 strains were sensitive,1 strains were resistant.There were 142 strains being not consistent between VITEK 2 Compact and E-test method.The results of VITEK 2 Compact were sensitive or intermediate,while E test were drug resistance.Conclusion VITEK 2 Compact is not reliable for the detection of CRKP to Amikacin,which requires that K B method or other methods should be used for the susceptibility of CRKP to Amikacin.

Sensibilidad a los antimicrobianos de aislamientos de Helicobacter pylori aislados de lesiones gástricas / Antimicrobial susceptibility of Helicobacter pylori strains isolated from gastric lesions

Se evaluó la sensibilidad a los antimicrobianos de 30 aislamientos de Helicobacter pylori aislados de biopsias gástricas mediante los métodos de difusión por discos y tiras de E-test. Los antimicrobianos evaluados fueron amoxicilina, claritromicina, metronidazol y ciprofloxacina. No se encontraron cepas resistentes a amoxicilina, el 17% (5/30) fueron resistentes a claritromicina, el 20% (6/30) a ciprofloxacina por ambos métodos, y el 37% (11/30) a metronidazol por E-test. Si bien el número de cepas estudiadas fue reducido, hubo una sola discrepancia en la interpretación de la sensibilidad cuando se compararon ambos métodos: el metronidazol fue categorizado como sensible por E-test e intermedio por el método de difusión por discos. No pudo determinarse una asociación estadísticamente significativa entre el tipo de lesión histológica y el patrón de resistencia encontrado.

Antimicrobial susceptibility was evaluated by two diffusion methods: E-test strips to determine minimum inhibitory concentration (MIC) and disk diffusion for amoxicillin, clarithromycin, metronidazole and ciprofloxacin in 30 Helicobacter pylori strains isolated from gastric biopsies. No strains were resistant to amoxicillin, 17% (5/30) were resistant to clarithromycin, 20% (6/30) ciprofloxacin by both methods, and 37% (11/30) to metronidazole by the E-test. Although the number of strains studied was reduced, there was a single mismatch in interpreting susceptibility when both methods were compared; the same mismatch was observed for metronidazole, being categorized as sensitive by the E-test and as intermediate by disk diffusion. No association between the histological type of lesion and the resistance pattern found could be determined.

Susceptibility of Acinetobacter baumannii isolates to eight antimicrobial agents tested by different methods / 中国感染与化疗杂志

Objective The purpose of this study was to analyze the susceptibility profile of Acinetobacter baumannii to antimicrobial agents,and validate the results of different antimicrobial susceptibility testing methods,for improving the quality of antibiotic resistance monitoring data.Methods The susceptibility data of Hebei Provincial Antimicrobial Resistant Investigation Net were analyzed retrospectively and 126 strains ofA.baumannii were collected.The susceptibility ofA.baumannii to piperacillintazobactam,amikacin,gentamicin,ciprofloxacin,levofloxacin,ceftazidime,imipenem,and meropenem was tested by E-test,KirbyBauer method and VITEK system.Results The susceptibility results of the 126 A.baumannii strains showed that the susceptibility to piperacillin-tazobactam,amikacin,gentamicin,levofloxacin and ceftazidime was significantly different between the three methods (P＜0.05).The categorical agreement,major error,minor error,and very major error of Kirby-Bauer method were within acceptable range.There were evident difference in classification consistency for piperacillin-tazobactam,amikacin,levofloxacin between Kirby-Bauer method and VITEK (P＜0.05).Conclusions Different antimicrobial susceptibility testing methods may lead to different results of resistance monitoring data.Bias may be generated in antibiotic resistance surveillance if different methods are used.The susceptibility results of piperacillin-tazobactam,amikacin,levofloxacin derived from VITEK system should be validated by Kirby-Bauer or E-test method.

Antifungal Susceptibility In Vitro Determined by the Etest(r) for Candida Obtained from the Oral Cavity of Irradiated and Elderly Individuals

This study aimed to evaluate the in vitro antifungal susceptibility of Candida species of head-and-neck-irradiated patients (Group 1), non-institutionalized (Group 2) and institutionalized elders (Group 3) using Etest(r) methodology. Candida was isolated from saliva and presumptively identified by CHROMagar Candida(r), confirmed by morphological criteria, carbohydrate assimilation (API 20C AUX(r)) and genetic typing (OPE 18). The collection was made from 29, 34 and 29 individuals (Groups 1, 2 and 3, respectively) with 67 isolates. Etest(r) strips (ketoconazole, itraconazole, fluconazole, amphotericin B and flucytosine) on RPMI (Roswell Park Memorial Institute) agar, on duplicate, were used to evaluate susceptibility. ATTC (American Type Culture Collection) 10231 (Candida albicans) was used as quality control. Among the 67 isolates of Candida species, most were susceptible to azoles, flucytosine and amphotericin B. None of the isolates showed resistance and dose-dependent susceptibility to amphotericin B. There were nine strains resistant to itraconazole, six to fluconazole and two to ketoconazole and ten dose-dependent, mainly to flucytocine. The highest MIC (minimum inhibitory concentration) to C. albicans, C. tropicalis, C. parapsilosis was 2.671 μg.mL-1, 8.104 μg.mL-1, 4.429 μg.mL-1, all for flucytosine. C. krusei and C. glabrata were associated with higher MIC for azoles and C. glabrata with higher MIC to flucytosine. In summary, susceptibility to all tested antifungal agents was evident. The isolates were more resistant to itraconazole and dose-dependent to flucytosine. A comparison of C. albicans in the three groups showed no outliers. Higher MIC was associated with C. krusei and C. glabrata.

Esse estudo objetivou avaliar a susceptibilidade antifúngica in vitro de espécies de Candida obtidas de pacientes irradiados em cabeça e pescoço (Grupo 1), idosos não institucionalizados (Grupo 2) e idosos institucionalizados (Grupo 3) usando a metodologia Etest(r). Candida foi isolada da saliva e identificada presuntivamente pelo teste CHROMagar Candida(r), confirmada pelo critério morfológico, assimilação de carboidratos API 20C AUX(r) e identificação genética (OPE 18). A coleta foi feita em 29, 34 e 29 indivíduos (Grupos 1, 2 and 3, respectivamente) com 67 isolados. As fitas de Etest(r) (cetoconazol, itraconazol, fluconazol, anfotericina B and flucitosina) em meio ágar RPMI (Roswell Park Memorial Institute), em duplicata, foram utilizados para avaliar a susceptibilidade. A ATTC (American Type Culture Collection) 10231 (Candida albicans) foi usada como controle de qualidade. Dos 67 isolados de espécies de Candida, a maioria foi susceptíveis aos azoles, flucitosina e anfotericina B. Nenhum dos isolados mostrou resistência ou susceptibilidade dose-dependente a anfotericina B. Houve nove espécies resistentes ao itraconazol, seis ao fluconazol e duas ao cetoconazol e dez dose-dependentes, principalmente a flucitosina. Os maiores valores de MIC (mínima concentração inibitória) para C. albicans, C. tropicalis, C. parapsilosis foram, respectivamente, 2,671 μg.mL-1, 8,104 μg.mL-1, 4, 429 μg.mL-1, todos para a flucitosina. C. krusei e C. glabrata foram associadas a um maior MIC para azoles e C. glabrata com maior MIC para flucitosina. Em resumo, a susceptibilidade a todos os antifúngicos testados foi evidente. Os isolados foram mais resistentes ao itraconazol e dose dependentes para a flucitosina. A comparação para C. albicans nos três grupos não mostrou diferença. Os maiores valores de MIC estavam relacionados a C. krusei e C. glabrata.

Molecular Identification and Amphotericin B Susceptibility Testing of Clinical Isolates of Aspergillus From 11 Hospitals in Korea

BACKGROUND: We investigated the species distribution and amphotericin B (AMB) susceptibility of Korean clinical Aspergillus isolates by using two Etests and the CLSI broth microdilution method. METHODS: A total of 136 Aspergillus isolates obtained from 11 university hospitals were identified by sequencing the internal transcribed spacer (ITS) and beta-tubulin genomic regions. Minimal inhibitory concentrations (MICs) of AMB were determined in Etests using Mueller-Hinton agar (Etest-MH) and RPMI agar (Etest-RPG), and categorical agreement with the CLSI method was assessed by using epidemiological cutoff values. RESULTS: ITS sequencing identified the following six Aspergillus species complexes: Aspergillus fumigatus (42.6% of the isolates), A. niger (23.5%), A. flavus (17.6%), A. terreus (11.0%), A. versicolor (4.4%), and A. ustus (0.7%). Cryptic species identifiable by beta-tubulin sequencing accounted for 25.7% (35/136) of the isolates. Of all 136 isolates, 36 (26.5%) had AMB MICs of > or =2 microg/mL by the CLSI method. The categorical agreement of Etest-RPG with the CLSI method was 98% for the A. fumigatus, A. niger, and A. versicolor complexes, 87% for the A. terreus complex, and 37.5% for the A. flavus complex. That of Etest-MH was < or =75% for the A. niger, A. flavus, A. terreus, and A. versicolor complexes but was higher for the A. fumigatus complex (98.3%). CONCLUSIONS: Aspergillus species other than A. fumigatus constitute about 60% of clinical Aspergillus isolates, and reduced AMB susceptibility is common among clinical isolates of Aspergillus in Korea. Molecular identification and AMB susceptibility testing by Etest-RPG may be useful for characterizing Aspergillus isolates of clinical relevance.

Antifungal Susceptibility Testing with Etest for Candida Species Isolated from Patients with Oral Candidiasis

BACKGROUND: The necessity of performing antifungal susceptibility tests is recently increasing because of frequent cases of oral candidiasis caused by antifungal-resistant Candida species. The Etest (BioMerieux, Marcy l'Etoile, France) is a rapid and easy-to-perform in vitro antifungal susceptibility test. OBJECTIVE: The purpose of this study was to determine the minimal inhibitory concentrations (MICs) of antifungal agents by using the Etest for Candida species isolated from patients with oral candidiasis. METHODS: Forty-seven clinical isolates of Candida species (39 isolates of Candida albicans, 5 isolates of C. glabrata, and 3 isolates of C. tropicalis) were tested along with a reference strain (C. albicans ATCC 90028). The MIC end points of the Etest for fluconazole, itraconazole, voriconazole, and amphotericin B susceptibility were read after the 24-hour incubation of each isolate on RPMI 1640 agar. RESULTS: All Candida isolates were found susceptible to voriconazole and amphotericin B. However, all five isolates of C. glabrata were resistant to itraconazole, among which two isolates were also resistant to fluconazole. CONCLUSION: This study revealed that the Etest represented a simple and efficacious method for antifungal susceptibility testing of Candida species isolated from oral candidiasis patients. Therefore, voriconazole and amphotericin B should be recommended as effective alternatives for the treatment of oral candidiasis.

Discordance in Colistin Susceptibility Test for Acinetobacter baumannii Showing Resistance: MicroScan versus Etest

BACKGROUND: Acinetobacter baumannii causes various hospital-acquired infections, its multidrug resistance is rapidly increasing worldwide. Although colistin is used in treatments against multidrug-resistant A. baumannii, resistance to colistin has also been reported recently. Few studies have reported colistin susceptibility testing using MicroScan. In this study, we compared colistin susceptibility tests for resistant A. baumannii by MicroScan (Siemens, USA) and Etest (BioMerieux, France). METHODS: We collected 115 A. baumannii clinical isolates, showing colistin resistance (minimum inhibitory concentration [MIC] > or =4 microg/mL) by MicroScan, from July 2014 to March 2015 at Kangdong Sacred Heart Hospital. Species identification and antimicrobial susceptibility tests were performed using the MicroScan Neg Combo Panel Type 72. Additionally, Etest was also performed for comparison. RESULTS: Of the 115 isolates, Etest revealed that 103 (89.6%) were colistin-susceptible (MIC 4 microg/mL by MicroScan were resistant to colistin according to the Etest. CONCLUSIONS: The MicroScan automated system, using the commercial broth microdilution method, exhibited some discrepancies with the Etest for colistin susceptibility in A. baumannii. Therefore, more practical and reliable susceptibility tests for colistin are required in clinical laboratories using MicroScan.

Antimicrobial susceptibility testing for Helicobacter pylori isolates from Brazilian children and adolescents: comparing agar dilution, E-test, and disk diffusion

Antimicrobial susceptibility testing for Helicobacter pylori is increasingly important due to resistance to the most used antimicrobials agents. Only agar dilution method is approved by CLSI, but it is difficult to perform routinely. We evaluated the reliability of E-test and disk diffusion comparing to agar dilution method on Helicobacter pylori antimicrobial susceptibility testing. Susceptibility testing was performed for amoxicillin, clarithromycin, furazolidone, metronidazole and tetracycline using E-test, disk-diffusion and agar dilution method in 77 consecutive Helicobacter pylori strains from dyspeptic children and adolescents. Resistance rates were: amoxicillin - 10.4%, 9% and 68.8%; clarithromycin - 19.5%, 20.8%, 36.3%; metronidazole - 40.2%33.7%, 38.9%, respectively by agar dilution, E-test and disk diffusion method. Furazolidone and tetracycline showed no resistance rates. Metronidazole presented strong correlation to E-test (r = 0.7992, p < 0.0001) and disk diffusion method (r=-0.6962, p < 0.0001). Clarithromycin presented moderate correlation to E-test (r = 0.6369, p < 0.0001) and disk diffusion method (r=-0.5656, p < 0.0001). Amoxicillin presented weak correlation to E-test (r = 0.3565, p = 0.0015) and disk diffusion (r=-0.3565, p = 0.0015). Tetracycline presented weak correlation with E-test (r = 0.2346, p = 0.04) and furazolidone to disk diffusion (r=-0.0288, p = 0.8038). E-test presented better agreement with gold standard. It is an easy and reliable method for Helicobacter pylori susceptibility testing. Disk diffusion method presented high disagreement and high rates of major errors.

The Evaluation of the Combination of Caspofungin with Voriconazole and Amphotericin B against Clinical Candida krusei Isolates by Etest and Disk Diffusion Methods.

Background: C. krusei is an opportunistic fungal pathogen that known of its intrinsic fluconazole resistance and its frequency is increasing especially among hematology patients. The increase in the frequency of high mortality fungal infections have accelerated the efforts of new drug development with broad spectrum, low toxicity and the studies including their combination. However, there is no standardized method to evaluate the activity of drug combinations. Aims: To evaluate the activity of caspofungin (CAS) with voriconazole (VOR) and amphotericin B (AMB) alone and in combination and the utility of Etest and disk diffusion methods for antifungal combinations. Methodology: The minimum inhibitory concentrations of VOR, CAS and AMB against 30 clinical C. krusei isolates were determined by using Etest, disk diffusion and reference broth microdilution methods. Combinations of CAS with VOR and CAS with AMB were evaluated using disk diffusion (three different ways) and Etest (two different ways) methods. Results: All isolates tested were susceptible to VOR and CAS in vitro by all three methods. Categorical agreements of Etest and disk diffusion methods with reference microdilutiontest were 100% for CAS and VOR (for each method), 86.7% and 50% for AMB, respectively. In the all ways of both combination methods, we did not observe distinctly antagonistic or synergic interaction. Conclusion: Etest and disk diffusion could be easy, convenient, and nontime-consuming alternative methods to evaluate the antifungal combinations. The combinations of CAS with VOR and AMB exhibited promising results because of an apparent antagonistic interaction was not detected in this study.

Determination of Vancomycin and Methicillin Resistance in Clinical Isolates of Staphylococcus aureus in Iranian Hospitals.

Aims: The aim of this study was to determine the prevalence of methicillin resistant S. aureus (MRSA), vancomycin resistant or vancomycin intermediate resistant S. aurues (aureus) (VRSA/VISA) among clinical isolates. Study Design: S.aureus isolates used in this study were randomly collected from in-patient and outpatient of several hospitals of 7 cities in Iran (Tehran, Shiraz, Zahedan, Tabriz, Sannandaj, Sari, and Ahvaz) during 2006-2008. Methodology: Antibiotic susceptibility of 250 strains of Staphylococcus aureus isolated from Iranian hospitals were determined by disk diffusion method. Minimum inhibitory concentration (MICs) were determined for oxacillin and vancomycin by E-test. PCRs were used by specific primers (PCR used specific primers) for detection of mecA, vanA, vanB genes. Results: The percentage of resistance by disk diffusion method was as below: methicillin 46%, vancomycin 0%, penicillin 86%, erythromycin 42%, ciprofloxacin 29%, gentamicin 39% and clindamycin 33%. E-test MIC method showed that 43% isolates were resistant to methicillin and 4% isolates were VISA (≤ 8μg/ml). The prevalence of resistance genes in the clinical isolates were: mecA 44%, vanA 0%, vanB 0%. Conclusion: This study revealed that clinical isolates have rather high resistance to methicillin, erythromycin, gentamicin, penicillin and clindamycin We did not observe resistance to vancomycin. In order to avoid a possible outbreak involving VISA), vancomycin should be used carefully as a drug for treatment of S. aureus infections.

Antimicrobial susceptibility profile of brucella spp. isolated in Brazil

The intention of this work was to investigate the susceptibility profile of 27 Brucella strains isolated from animals in Brazil, using the E-test method with antimicrobials recommended for the treatment of human brucellosis, to monitor the activities of these antimicrobials and their potential efficacy for human brucellosis treatment. Efficiency of SE-AFLP in determining the genetic diversity of the species of Brucella and its correlation with their susceptibility profile was also evaluated. All 27 strains were susceptible to doxycycline. With the exception of one strain of B. canis and of B. abortus, all strains were susceptible to gentamicin and streptomycin. Of the wild Brucella strains tested, ten, nine and five showed reduced susceptibility to rifampicin, ceftriaxone and trimetoprim/sulfamethoxazole, respectively. One B. abortus and three B. canis strains showed multi-resistance profiles. The strain of B. abortus was resistant to streptomycin, rifampicin and ceftriaxone. Two strains of B. canis were resistant to rifampicin, ceftriaxone and trimetoprim/sulfamethoxazole, and one strain was resistant to rifampicin, ceftriaxone, streptomycin and gentamicin. Rifampicin, in combination with doxycycline, is one of the principal antibiotics prescribed to treat human brucellosis. The occurrence of strains resistant to rifampicin and other antimicrobials must be monitored before initiating this treatment, since the resistance of these strains could be one of the causes of the failure of some brucellosis treatment. No relationship was observed between SE-AFLP profiles and regional origin of the strains; neither between SE-AFLP profiles and antimicrobial profiles...

O objetivo deste trabalho foi investigar o perfil de susceptibilidade de 27 cepas de Brucella isoladas de animais no Brasil, utilizando-se o método E-test com os antimicrobianos recomendados para o tratamento da brucelose humana. Com este método, pretendeu-se monitorar a atividade destes antimicrobianos e seu potencial de eficacidade no tratamento desta enfermidade no homem. Também foi avaliada a eficiência da técnica SE-AFLP para discriminar as diferentes cepas de Brucella sp. e para analisar se os perfis gerados mostram alguma relação com os resultados de susceptibilidade. Todas as 27 cepas testadas foram sensíveis à doxiciclina, com exceção de uma cepa de B. canis e outra de B. abortus; as demais cepas foram sensíveis à gentamicina e à estreptomicina. Do total de cepas de campo testadas, respectivamente, dez, nove e cinco apresentaram susceptibilidade reduzida à rifampicina, ceftriaxona e trimetoprim/sulfametoxazol. Uma cepa de B. abortus e três de B. canis apresentaram perfil de multirresistência. A cepa de B. abortus mostrou-se resistente à estreptomicina, rifampicina e ceftriaxona. Duas cepas de B. canis foram resistentes à rifampicina, ceftriaxona e trimetoprim/sulfametoxazol e uma cepa foi resistente à rifampicina, ceftriaxona, streptomicina e gentamicina. Rifampicina e doxiciclina, associadas, são os principais antibióticos recomendados para o tratamento da brucelose humana. A ocorrência de cepas resistentes à rifampicina e outros antimicrobianos deve ser monitorada antes do início do tratamento, pois a resistência a esses antimicrobianos pode ser uma das causas do insucesso de alguns tratamentos de brucelose. Não foi observada nenhuma correlação entre os perfis SE- AFLP gerados e a origem das cepas, nem com os perfis de susceptibilidade destas cepas...

Comparative evaluation of disk diffusion and E-test methods for clarithromycin susceptibility testing of Helicobacter pylori / 中华临床感染病杂志

Objective To compare disk diffusion with E-test methods for clarithromycin susceptibility testing of Helicobacter pylori (H.pylori).Methods A total of 44 strains of H.pylori were isolated from gastric mucosa biopsy from patients undergoing gastroscopic examination.Disk diffusion and E-test methods were used for clarithromycin susceptibility testing of H.pylori.The agreement of disk diffusion and E-test was assessed by linear regression analysis.Results The minimum inhibitory concentration (MIC) tested by E-test method ranged from 0.016 to 256 μg/mL,and drug resistance was observed in 12(27.3％) isolates.In range of 0-35 mm of inhibition diameter,the results of disk diffusion method were correlated well with the MICs obtained by E-test method (r2 =0.91,P ＜0.01).Regression analysis showed that with inhibition diameters≥ 18 mm as considered sensitive to clarithromycin and ≤ 15 mm as resistant,the agreement was 100％ between two methods.Conclusion The disk diffusion method is equivalent to the E-test method for clarithromycin susceptibility testing of H.pylori,which can be an alternative method for clinical application.

Validación del agar Mueller Hinton modificado para la determinación de las concentraciones mínimas inhibitorias a los antifúngicos por etest en candida spp / Validation of the modified Mueller Hinton agar for the determination of the minimum inhibitory concentrations to antifungals by E-test in Candida spp

En este trabajo de investigación se determinaron las Concentraciones Mínimas Inhibitorias (CMI) de los antifúngicos fluconazol, voriconazol, posaconazol, caspofungina, anidulafungina y anfotericina B, por los métodos de microdilución en caldo y difusión en agar con Etest, empleando RPMI 1640 agar y Mueller Hinton modificado (MHm), en 102 cepas de Candida spp., aisladas de sangre, provenientes de la Red de Candidemia del INHRR. El objetivo fue validar el empleo del MHm como medio de cultivo confiable en el método de Etest para la obtención de las CMI. Se utilizaron las cepas C. parapsilosis ATCC 22019 y C. krusei ATCC 6258 como control de calidad. Los resultados demostraron un 94% de frecuencia para C. no albicans y un 6% para C. albicans. Se obtuvo un 100% de sensibilidad para las equinocandinas y anfotericina B, en todas las especies. El MHm demostró una elevada reproducibilidad con respecto al RPMI agar y el método de referencia microdilución en caldo. En base a los resultados obtenidos en esta investigación, se logró la validación del medio MHm para la determinación de las CMI por Etest, así como la detección de resistencia, recomendándolo como metodología confiable, accesible y de fácil ejecución para uso rutinario en el laboratorio de microbiología.

In this research, the Minimum Inhibitory Concentrations (MICs) of the antifungal agent's fluconazole, voriconazole, posaconazole, caspofungin, anidulafungin and amphotericin B were determined by broth microdilution and agar diffusion Etest methods, using RPMI 1640 agar and modified Mueller Hinton (mHM), in 102 strains of Candida spp., isolated from blood, from the Candidemia Network of the INHRR. The objective was to validate the use of mHM as a reliable culture medium for the Etest method to obtain MICs. As a quality control, the strains C. parapsilosis ATCC 22019 and C. krusei ATCC 6258 were used. The results demonstrated a 94% of frequency for non C. albicans and 6% for C. albicans. A 100% of sensitivity was obtained for echinocandins and amphotericin B in all species. The mHM showed high reproducibility with respect to RPMI agar and the reference method of microdilution broth. Based on the results obtained in this investigation, the validation of mHM medium, for the determination of MICs by Etest, as well as the resistance detection was achieved, recommending it as a reliable, affordable and easy to implement method for the routine use in the microbiology laboratory.

Antimicrobial susceptibility of Neisseria gonorrhoeae isolates from patients attending a public referral center for sexually transmitted diseases in Belo Horizonte, State of Minas Gerais, Brazil

Introduction The aim of this study was to determine the antimicrobial susceptibility of Neisseria gonorrhoeae isolates obtained from patients attending a public referral center for sexually transmitted diseases and specialized care services (STD/SCS) in Belo Horizonte, Brazil. Methods Between March 2011 and February 2012, 201 specimens of Neisseria gonorrhoeae were consecutively obtained from men with symptoms of urethritis and women with symptons of cervicitis or were obtained during their initial consultation. The strains were tested using the disk diffusion method, and the minimum inhibitory concentrations of azithromycin, cefixime, ceftriaxone, ciprofloxacin, chloramphenicol, penicillin, tetracycline and spectinomycin were determined using the E-test. Results The specimens were 100% sensitive to cefixime, ceftriaxone and spectinomycin and exhibited resistances of 4.5% (9/201), 21.4% (43/201), 11.9% (24/201), 22.4% (45/201) and 32.3% (65/201) to azithromycin, ciprofloxacin, chloramphenicol, penicillin and tetracycline, respectively. Intermediate sensitivities of 17.9% (36/201), 4% (8/201), 16.9% (34/201), 71.1% (143/201) and 22.9% (46/201) were observed for azithromycin, ciprofloxacin, chloramphenicol, penicillin and tetracycline, respectively. The specimens had plasmid-mediated resistance to penicillin PPNG 14.5% (29/201) and tetracycline TRNG 11.5% (23/201). Conclusions The high percentage of detected resistance to penicillin, tetracycline, chloramphenicol and ciprofloxacin indicates that these antibiotics are not appropriate for gonorrhea treatment at the Health Clinic and possibly in Belo Horizonte. The resistance and intermediate sensitivity of these isolates indicates that caution is recommended in the use of azithromycin and emphasizes the need to establish mechanisms for the surveillance of antimicrobial resistance for the effective control of gonorrhea. .

Combined antimicrobial susceptibility test against pan-drug-resistant Acinetobacter baumannii with E-test and microdilution checkerboard assay / 中华微生物学和免疫学杂志

Objective To evaluate the activity of antibiotics against pan-drug-resistant (PDR) Acinetobacter baumannii by combination antimicrobial susceptibility test in viro with epsilometric methods (Etest method) and microdilution checkerboard (CB method),and to detect a good correlation between timekill curve with the above mentioned two assays.Methods Thirty-one clinical isolates of PDR Acinetobacter baumannii were selected for mono and combination antimicrobial susceptibility test in vitro by E-test and CB method,then a comparison was conducted between the test results and the time-kill curve.Mono drugs involved tigecycline,colistin,imipenem and amikacin,and combinations involved two of drugs above,and three drugs involved imipenem/tigecycline,plus amikacin combination.Results Synergistic effect was detected in imipenem plus colistin and tigecycline plus imipenem combination.A high comparability was revealed between the E-test method with antimicrobial drugs added into the culture medium and the time-kill curves.Synergy in the combination of imipenem/tigecycline,plus amikacin was detected by the CB method and time-kill curves.Conclusion The results showed that the effect of specific combination of antibiotics against PDR Acinetobacter baumannii could be predicted by testing their synergistic effect with combination antimicrobial susceptibility test.

Susceptibilidad de candida spp, aislados de sangre, a fluconazol, voriconazol, anfotericina B, y caspofungina, por los métodos de microdilución en caldo (EUCAST) y el método de difusión en agar (ETEST) / Susceptibility of candida spp; blood isolates to fluconazole, voriconazole, amphotericin B, and caspofungin by broth microdilution methods (EUCAST) and the agar diffusion method (ETEST)

La Candidiasis invasora es una de las principales infecciones Nosocomiales. El desarrollo de los triazoles, inició el uso masivo de la profilaxis antifúngica y de la terapia empírica. Estas prácticas terapéuticas han generado cambios epidemiológicos, entre los que destacan la aparición de cepas que han desarrollado resistencia secundaria a los antifúngicos y la sustitución de algunas especies sensibles por otras con resistencia intrínseca. En este estudio se evaluaron 189 aisladas de sangre de la Red de Candidemia del INHRR determinando la Concentración Mínima Inhibitoria (CMI) a fluconazol, voriconazol, caspofungina y anfotericina b por los métodos Microdilución en caldo EUCAST y Etest, de cada una de las levaduras, siguiendo los procedimientos del método documento E. Dis. 7.1 del EUCAST y del fabricante. Se utilizaron las cepas C. parapsilosis ATCC 22019 y C. krusei ATCC 6258 como control de calidad. Los aislados fueron 89% sensibles para fluconazol por EUCAST y 87% por Etest, para voriconazol por ambos métodos 97% sensibles y para caspofungina y anfotericina B tasas muy bajas de resistencia se obtuvier. Se obtuvo una Concordancia del 94,8% y una Especificidad de 82,4%. Voriconazol 88,4% de Concordancia con unos límites de confianza de 82,9 a 92,5% y una Especificidad del 100%. Caspofungina se obtuvo un Concordancia de 98,4%y Sensibilidad del 100%. Se obtuvo una excelente concordancia entre los métodos evaluados, de manera que pueden ser utilizados indistintamente en la detección de susceptibilidad y/o resistencia antifúngica. Se determinaron puntos de corte epidemiológicos locales para fluconazol, voriconazol, caspofungina y anfotericina B en las especies de Candida frecuentemente aisladas mucho más sensible para detectar la posible emergencia de cepas resistente en nuestro medio.

Invasive candidiasis is a major nosocomial infections. With the development of the triazoles, began the widespread use of antifungal prophylaxis and empiric therapy, which has generated epidemiological changes. In this study, we evaluated 189 blood isolates from Network Candidemia INHRR of determining the minimum inhibitory concentration (MIC) to fluconazole, voriconazole, amphotericin B and caspofungin by EUCAST broth microdilution methods and ETEST. Strains were used C. parapsilosis ATCC 22019 and C. krusei ATCC 6258 as quality control. The group was 16.4% C. albicans and 83.6% C no albicans. C. parapsilosis (48%) the most frequently isolated species. The susceptibility of the total was isolated by EUCAST and Etest of 89/87% 97/97%, m99.5/98% 98/99% to fluconazole, voriconazole, amphotericin B and caspofungin respectively. General resistance to fluconazole was 9% and 11% EUCAST Etest for voriconazole amphotericin B, and caspofungin resistance did not exceed 4% of the total. Were determined epidemiological cutoff value (ECV) local to fluconazole, voriconazole, caspofungin and amphotericin B for C. albicans, C. parapsilosis and C. tropicalis which accounted for 89% of the total. The ECV is more sensitive to detect the possible emergence of resistant strains in our setting. The agreement obtained for the 4 antifungal was between 97.4 and 100% with a sensitivity of 95.9 to 100%. The data obtained are recommended ETEST for their sensitivity and consistency with respect to the reference method proving to be even more effective in detecting resistance. With the support of our local data allow the clinician to establish early and adequate therapy to finally benefit the patient.