Membranome-based identification of amino acid substitution in Haemophilus influenzae multidrug efflux pump HmrM for reduced chloramphenicol susceptibility.

A decreased chloramphenicol susceptibility in Haemophilus influenzae is commonly caused by the activity of chloramphenicol acetyltransferases (CATs). However, the involvement of membrane proteins in chloramphenicol susceptibility in H. influenzae remains unclear. In this study, chloramphenicol susceptibility testing, whole-genome sequencing, and analyses of membrane-related genes were performed in 51 H. influenzae isolates. Functional complementation assays and structure-based protein analyses were conducted to assess the effect of proteins with sequence substitutions on the minimum inhibitory concentration (MIC) of chloramphenicol in CAT-negative H. influenzae isolates. Six isolates were resistant to chloramphenicol and positive for type A-2 CATs. Of these isolates, A3256 had a similar level of CAT activity but a higher chloramphenicol MIC relative to the other resistant isolates; it also had 163 specific variations in 58 membrane genes. Regarding the CAT-negative isolates, logistic regression and receiver operator characteristic curve analyses revealed that 48T > G (Asn16Lys), 85 C > T (Leu29Phe), and 88 C > A (Leu30Ile) in HI_0898 (emrA), and 86T > G (Phe29Cys) and 141T > A (Ser47Arg) in HI_1177 (artM) were associated with enhanced chloramphenicol susceptibility, whereas 997G > A (Val333Ile) in HI_1612 (hmrM) was associated with reduced chloramphenicol susceptibility. Furthermore, the chloramphenicol MIC was lower in the CAT-negative isolates with EmrA-Leu29Phe/Leu30Ile or ArtM-Ser47Arg substitution and higher in those with HmrM-Val333Ile substitution, relative to their counterparts. The Val333Ile substitution was associated with enhanced HmrM protein stability and flexibility and increased chloramphenicol MICs in CAT-negative H. influenzae isolates. In conclusion, the substitution in H. influenzae multidrug efflux pump HmrM associated with reduced chloramphenicol susceptibility was characterised.

Molecular basis of the persistence of chloramphenicol resistance among Escherichia coli and Salmonella spp. from pigs, pork and humans in Thailand.

This study aimed to investigate the potential mechanisms associated with the persistence of chloramphenicol (CHP) resistance in Escherichia coli and Salmonella enterica isolated from pigs, pork, and humans in Thailand. The CHP-resistant E. coli (n = 106) and Salmonella (n = 57) isolates were tested for their CHP susceptibility in the presence and absence of phenylalanine arginine ß-naphthylamide (PAßN). The potential co-selection of CHP resistance was investigated through conjugation experiments. Whole genome sequencing (WGS) was performed to analyze the E. coli (E329, E333, and E290) and Salmonella (SA448, SA461, and SA515) isolates with high CHP MIC (32-256 µg/mL) and predominant plasmid replicon types. The presence of PAßN significantly reduced the CHP MICs (≥4-fold) in most E. coli (67.9%) and Salmonella (64.9%). Ampicillin, tetracycline, and streptomycin co-selected for CHP-resistant Salmonella and E. coli-transconjugants carrying cmlA. IncF plasmids were mostly detected in cmlA carrying Salmonella (IncFIIAs) and E. coli (IncFIB and IncF) transconjugants. The WGS analysis revealed that class1 integrons with cmlA1 gene cassette flanked by IS26 and TnAs1 were located on IncX1 plasmid, IncFIA(HI1)/HI1B plasmids and IncFII/FIB plasmids. IncFIA(HI1)/HI1B/Q1in SA448 contained catA flanked by IS1B and TnAs3. In conclusion, cross resistance through proton motive force-dependent mechanisms and co-selection by other antimicrobial agents involved the persistence of CHP-resistance in E. coli in this collection. Dissemination of CHP-resistance genes was potentially facilitated by mobilization via mobile genetic elements.

Molecular detection of chloramphenicol-florfenicol resistance (cfr) genes among linezolid resistant MRSA isolates in Sokoto State, Nigeria / Detecção molecular de genes de resistência ao cloranfenicol-florfenicol (cfr) entre isolados de MRSA resistentes a linezolida no estado de Sokoto, Nigéria

Objective: we investigated previous literatures for documentation of the trend in Sokoto, Nigeria and found none. We deemed it fit to determine the frequency of linezolid resistance mediated by cfr gene among MRSA isolates from Sokoto State-owned hospitals. Methods: Bacterial species identification was carried out with Microgen™ Staph-ID System kit (Microgen, Surrey, UK). Disc agar diffusion method (Modified Kirby-Bauer's) following Clinical and Laboratory Standards Institute (CLSI 2018) guidelines was used in antimicrobial susceptibility testing. The results were interpreted and managed using WHONET 5.6 software (WHO, Switzerland). Oxacillin resistant screening agar base (ORSAB) culture was used to determine phenotypic methicillin resistance. Polymerase chain reaction (PCR) was carried out to determine the presence of cfr-gene. Results: A total of 81 S. aureus isolates were phenotypically identified. Of this number, 46.91% (38/81) were MRSA; Healthcare workers (39.5%), Outpatient (28.9%), In patient (21%), Security men and Cleaners (5.3% each). Importantly linezolid resistance rate among the MRSA isolates was 44.7%. Analysis of antimicrobial susceptibility profile also showed a multiple antibiotics resistance burden of MDR (5.9%), possible XDR (47.1%), XDR (41.1%) and PDR (5.9%) amongst LR-MRSA. About 52.9% (9/17) of LR-MRSA harbored the cfr gene. Conclusions: This is the first report to document cfr gene in LR-MRSA strains in Sokoto. The cfr gene was found among the studied LR-MRSA strains and if cfr-mediated linezolid resistance is not properly checked, its phenotypic expression may result in an outbreak of multiple antibiotic resistant strains.

Objetivo: avaliar a incidência de resistência linezolida cfr-mediada entre os isolados de MRSA dos hospitais do Estado de Sokoto. Métodos: A identificação das espécies bacterianas foi realizada com Microgen™ Staph-ID System kit (Microgen, Surrey, UK). Método de difusão em ágar de disco (Kirby-Bauer modificado) seguindo as diretrizes do Clinical and Laboratory Standards Institute (CLSI 2018). O resultado foi interpretado e gerido com WHONET 5.6 (OMS, Suíça) software. A cultura ORSAB (Oxacillin resistant screening agar) foi utilizada para determinar a resistência fenotípica à meticilina. A PCR foi realizada para determinar a presença de cfr-gene. Resultados: um total de 81 isolados de S. aureus foi identificada fenotipicamente. Desse número, 46,91% (38/81) eram de MRSA; Profissionais de saúde (39,5%), Ambulatoriais (28,9%), Em paciente (21%), Homens de segurança e Limpadores (5,3% cada). A taxa de resistência linezolida entre os isolados de MRSA foi de 44,7%. A análise do perfil de sensibilidade antimicrobiana também mostrou uma carga de resistência a antibióticos múltiplos de MDR (5,9%), possível XDR (47,1%), XDR (41,1%) e PDR (5,9%) entre LR-MRSA. Um total de, 52,9% (9/17) da LR-MRSA abrigava o gene cfr. Conclusões: Este é o primeiro relatório a documentar o cfr-gen nas estirpes LR-MRSA em Sokoto. O gene cfr está presente entre as cepas estudadas de LR-MRSA, e se a resistência cfr-mediated linezolida não for adequadamente verificada, sua expressão fenotípica pode resultar em um surto de múltiplas cepas resistentes a antibióticos.

Resistencia antimicrobiana de cepas de Bartonella bacilliformis procedentes de regiones endémicas de la enfermedad de Carrión en el Perú / Antimicrobial resistance of Bartonella bacilliformis strains from regions endemic to bartonellosis in Peru

Evaluar la susceptibilidad antimicrobiana in vitro a cloranfenicol (CHL) y ciprofloxacino (CIP) de cepas de Bartonella bacilliformis procedentes de áreas endémicas de la enfermedad de Carrión (EC) en el Perú, mediante tres métodos de laboratorio. Materiales y métodos. Se evaluó la susceptibilidad antimicrobiana a CHL y CIP de 100 cepas de Bartonella bacilliformis, los aislamientos procedieron de pacientes de los departamentos de Ancash, Cusco, Cajamarca, Lima y La Libertad; las cepas se evaluaron mediante: disco difusión, E-Test y dilución en agar. Resultados. El 26% de las cepas de Bartonella bacilliformis evaluadas, presentaron resistencia a CIP y 1% a CHL. Se obtuvieron patrones similares de sensibilidad/resistencia antimicrobiana en los tres métodos utilizados. Conclusiones. Las cepas de Bartonella bacilliformis circulantes en el Perú, presentan elevados niveles de resistencia in vitro a CIP, por lo que se recomienda ampliar la investigación sobre la utilización del fármaco en los esquemas de tratamiento de la EC. Los métodos de E-test y disco difusión resultaron más convenientes para la evaluación de la susceptibilidad antimicrobiana in vitro del microorganismo...

To evaluate in vitro antimicrobial susceptibility to chloramphenicol (CHL) and ciprofloxacin (CIP) in strains of Bartonella bacilliformis from areas that are endemic to Bartonellosis in Peru, through three laboratory methods. Materials and methods. Antimicrobial susceptibility to CHL and CIP from 100 strains of Bartonella bacilliformis isolated in patients from the regions of Ancash, Cusco, Cajamarca, Lima and La Libertad were evaluated. Strains were evaluated by: disk diffusion, E-test and agar dilution. Results. 26% of the strains of Bartonella bacilliformis evaluated were resistant to CIP and 1% to CHL. Similar patterns of antimicrobial sensitivity / resistance were obtained in all three methods. Conclusions. Bartonella bacilliformis strains circulating in Peru have high levels of in vitro resistance to CIP, so it is advisable to expand research on the use of drug treatment regimens of the Bartonellosis. The methods of E-test and disk diffusion were the most suitable for assessment in vitro of antimicrobial susceptibility of the microorganism...

Evaluation of Haemophilus influenzae type b carrier status among children 10 years after the introduction of Hib vaccine in Brazil

The aim of the present study was to assess the prevalence of Haemophilus influenzaetype b (Hib) nasopharyngeal (NP) colonisation among healthy children where Hib vaccination using a 3p+0 dosing schedule has been routinely administered for 10 years with sustained coverage (> 90%). NP swabs were collected from 2,558 children who had received the Hib vaccine, of whom 1,379 were 12-< 24 months (m) old and 1,179 were 48-< 60 m old. Hi strains were identified by molecular methods. Hi carriage prevalence was 45.1% (1,153/2,558) and the prevalence in the 12-< 24 m and 48-< 60 m age groups were 37.5% (517/1,379) and 53.9% (636/1,179), respectively. Hib was identified in 0.6% (16/2,558) of all children in the study, being 0.8% (11/1,379) and 0.4% (5/1,179) among the 12-< 24 m and 48-< 60 m age groups, respectively. The nonencapsulate Hi colonisation was 43% (n = 1,099) and was significantly more frequent at 48-< 60 m of age (51.6%, n = 608) compared with that at 12-< 24 m of age (35.6%, n = 491). The overall resistance rates to ampicillin and chloramphenicol were 16.5% and 3.7%, respectively; the co-resistance was detected in 2.6%. Our findings showed that the Hib carrier rate in healthy children under five years was very low after 10 years of the introduction of the Hib vaccine.

Characterization of Salmonella spp. Clinical Isolates in Gyeongsangbuk-do Province, 2012 to 2013 / 대한임상미생물학회지

BACKGROUND: Extended-spectrum cephalosporins and fluoroquinolones are important antimicrobials for treating invasive salmonellosis, and emerging resistance to these antimicrobials is of paramount concern. METHODS: A total of 30 Salmonella spp. clinical isolates recovered in Gyeongsangbuk-do from 2012 to 2013 were characterized using antibiotic resistance profiles and pulsed-field gel electrophoresis (PFGE). RESULTS: A high prevalence of multidrug-resistant isolates, mainly showing an ampicillin, nalidixic acid, chloramphenicol resistance pattern, was observed. Four extended-spectrum beta-lactamase (ESBL)-producing isolates (3 CTX-M-15 isolates and 1 CTX-M-27 isolate) were found. The bla(CTX-M-27) gene was carried by an IncF conjugative plasmid in the S. Infantis isolate. The bla(CTX-M-15) gene were carried by an IncF (2 isolates) or IncHI2 (1 isolate) conjugative plasmid in S. Enteritidis. In addition, a single mutation of GyrA, Ser83Thr (1 isolates), Asp87Tyr (9 isolates), Asp87Gly (4 isolates), and Asp87Leu (3 isolates), was detected in nalidixic acid-resistant Salmonella spp. isolates. XbaI PFGE analysis of all isolates revealed more than 19 different pulsotypes. The most common S. Enteritidis PFGE pattern (SEGX01.003) was associated with a larger number of cases of invasive salmonellosis than all other patterns. CONCLUSION: The information from our study can assist in source attribution, outbreak investigations, and tailoring of interventions to maximize disease prevention.

Characterization of Escherichia coli virulence genes, pathotypes and antibiotic resistance properties in diarrheic calves in Iran

BACKGROUND: Calf diarrhea is a major economic concern in bovine industry all around the world. This study was carried out in order to investigate distribution of virulence genes, pathotypes, serogroups and antibiotic resistance properties of Escherichia coli isolated from diarrheic calves. RESULTS: Totally, 76.45% of 824 diarrheic fecal samples collected from Isfahan, Chaharmahal, Fars and Khuzestan provinces, Iran were positive for E. coli and all of them were also positive for cnf2, hlyA, cdtIII, f17c, lt, st, stx1, eae, ehly, stx2 and cnf1 virulence genes. Chaharmahal had the highest prevalence of STEC (84.61%), while Isfahan had the lowest (71.95%). E. coli serogroups had the highest frequency in 1-7 days old calves and winter season. Distribution of ETEC, EHEC, AEEC and NTEC pathotypes among E. coli isolates were 28.41%, 5.07%, 29.52% and 3.49%, respectively. Statistical analyses were significant for presence of bacteria between various seasons and ages. All isolates had the high resistance to penicillin (100%), streptomycin (98.25%) and tetracycline (98.09%) antibiotics. The most commonly detected resistance genes were aadA1, sul1, aac[3]-IV, CITM, and dfrA1. The most prevalent serogroup among STEC was O26. CONCLUSIONS: Our findings should raise awareness about antibiotic resistance in diarrheic calves in Iran. Clinicians should exercise caution when prescribing antibiotics.

Identification and modeling of a novel chloramphenicol resistance protein detected by functional metagenomics in a wetland of Lerma, Mexico

The exploration of novel antibiotic resistance determinants in a particular environment may be limited because of the presence of uncultured microorganisms. In this work, a culture independent approach based on functional metagenomics was applied to search for chloramphenicol resistance genes in agro-industrial wastewater in Lerma de Villada, Mexico. To this end, a metagenomic library was generated in Escherichia coli DH10B containing DNA isolated from environmental samples of the residual arsenic-enriched (10 mg/ml) effluent. One resistant clone was detected in this library and further analyzed. An open reading frame similar to a multidrug resistance protein from Aeromonas salmonicida and responsible for chloramphenicol resistance was identifi ed, sequenced, and found to encode a member of the major facilitator superfamily (MFS). Our results also showed that the expression of this gene restored streptomycin sensitivity in E. coli DH10B cells. To gain further insight into the phenotype of this MFS family member, we developed a model of the membrane protein multiporter that, in addition, may serve as a template for developing new antibiotics (AU)

No disponible

Resistência antimicrobiana em Enterococcus faecalis e Enterococcus faecium isolados de carcaças de frango / Antimicrobial Resistance of Enterococcus faecalis and Enterococcus faecium isolated from poultry carcasses

O objetivo deste trabalho foi realizar o isolamento e analisar o perfil de resistência antimicrobiana de Enterococcus de carcaças de frango resfriadas e congeladas comercializadas no Distrito Federal, detectando genes de resistência antimicrobiana e identificando as espécies Enterococcus faecalis e Enterococcus faecium por reação polimerase em cadeia. Foram analisadas 100 carcaças de frangos, das quais foram isoladas 50 cepas de Enterococcus spp., sendo 42% de E. faecalis e 2% de E. faecium. O teste de susceptibilidade antimicrobiana demonstrou que todas as cepas isoladas apresentaram resistência a pelo menos um antimicrobiano, dos quais 90,47% das cepas de E. faecalis, 100% das cepas de E. Faecium e 82,14% dos Enterococcus spp. apresentaram resistência à Tetraciclina; 80,95% das cepas de E. faecalis e 35,71% das cepas de Enterococcus spp. foram resistentes à Eritromicina; 39,28% dos Enterococcus spp. e 23,80% dos E. faecalis à Ciprofloxacina e 28,57% dos E. faecalis apresentaram resistência ao Cloranfenicol. Foram detectados os genes de resistência antimicrobiana erm(B), vanC-1, aph(3')-llla, ant(6)-la, vanB, vanA, aac(6')-le-aph(2'')-la, erm(A) e tet(M) - este último mais frequente. Estes resultados sugerem sérios problemas para a Saúde Pública, uma vez que esses microrganismos podem possuir a capacidade de transmitir genes de resistência antimicrobiana para outros microrganismos presentes na microbiota intestinal de humanos e animais, podendo inviabilizar o uso destas drogas para tratamentos clínicos.

The aim of this study was to isolate and analyze the antimicrobial profile resistance of Enterococcus from cooled and frozen poultry carcasses commercialized at the Federal District area, detecting the antimicrobial resistance genes and identifying Enterococcus faecalis and Enterococcus faecium by polymerase chain reaction. One hundred poultry carcasses were analyzed and 50 strains of Enterococcus spp. were isolated, of which 42% were E. faecalis and 2% E. faecium. The antimicrobial susceptibility test showed that all isolates were resistant to at least one antibiotic; 90,47% of E. faecalis, 100% of E. faecium and 82,14% of Enterococcus spp. were resistant to Tetracycline; 80,95% of E. faecalis and 35,71% of Enterococcus spp. strains were resistant to Erythromycin; 39,28% of Enterococcus spp. and 23,80% of E. faecalis to Ciprofloxacin, and 28,57% of E. faecalis were resistant to Chloramphenicol. There were detected erm(B), vanC-1, aph(3')-llla, ant(6)-la, vanB, vanA, aac(6')-le-aph(2'')-la, erm(A) and tet(M) resistance genes, the last one most often verified. The results might suggest problems for public health due the high resistance, since these microorganisms have ability to transmit genes for antimicrobial resistance to others in the intestinal tract of humans and animals. Thus, the use of these drugs for clinical treatment could be hindered.

Genetic and physical map of broad host range cosmid pRG930cm

We hereby present the complete sequence and annotation of pRG930cm, a spectinomycin/streptomycin/chloramphenicol-resistant cosmid vector. pRG930cm (17,256 bp; GenBank Accession No.: FM174471) has a broad host range, and is stably maintained by a number of Gram-negative bacteria including Pseudomonas spp, Escherichia coli, Agrobacterium tumefaciens and Azorhizobium caulinodans ORS571. pRG930cm is already widely used and its sequence will aid efficient construction and analysis of cosmid libraries.

Cloning and characterization of the chloramphenicol resistant gene of Serratia marcescens strain KMR-3 / 生物工程学报

Chloramphenicol-resistant gene was cloned and analyzed by constructing genomic DNA library of Serratia marcescens KMR-3. It showed that cloned chloramphenicol-resistant gene encoded a protein product of 397 amino acids. The protein belonged to PRK10473 protein, and it showed 92% similarity to drug resistance transporter, Bcr/CflA subfamily of Serratia proteamaculans 568. Regulation elements including promoter, terminator, Shine-Dalgarno (SD) sequence and transcription start site also were identified.

Susceptibilidad in vitro de bacterias anaeróbicas en infecciones pleuropulmonares / In vitro antimicrobial susceptibility of anaerobic bacteria isolated from pleuropulmonary infections

Background: Aspirative pleuropulmonary infections are usually caused by anaerobic flora of the mouth, mainly Prevotella, Fusobacterium and Peptostreptococcus spp. Penicillin in high doses is the traditional treatment for this type of infections but the rising resistance developed in recent years has induced the empiric use of clindamycin, increasing treatment costs. Aim: To study antimicrobial susceptibility of anaerobic bacteria isolated from pleuropulmonary infections. Material and methods: Thirty two strains obtained from bronchoalveolar lavage and 15 strains isolated from pleural effusions between 2000 and 2002, were studied. The phenotype of strains was identified using the semiautomated API 20 A method and their susceptibility to penicillin (PNC), clindamycin (CM) and chloramphenicol (CAF) was tested using the E test methods. Results: All the strains were susceptible to CAF, 95% to CM and 74.4% to PNC. The predominant genus was Prevotella, which also exhibited the higher resistance. Conclusions: As CM and CAF are active "in vitro", high rates of clinical response should be expected. In contrast, PNC is less effective, especially against pigmented Prevotella.

Evidencia in vitro de la utilidad de cloranfenicol y rifampicina para el tratamiento de infecciones sistémicas y meningitis causadas por Streptococcus pneumoniae aislados de niños menores de 5 años en Colombia / Effectiveness of the antibiotics chloramfenicol and rifampin in the treatment of Streptococcus pneumoniae-induced meningitis and systemic infections

Actualmente, Streptococcus pneumoniae resistente a penicilina es un patógeno común en infecciones pediátricas, lo cual plantea dificultades en el tratamiento. La rifampicina y el cloranfenicol se han recomendado como antibióticos útiles y como alternativas en estos casos, pues son menos costosos y más accesibles a las comunidades de recursos limitados. Su uso, sin embargo, puede estar limitado por los niveles de resistencia encontrados en diferentes poblaciones. El objetivo del presente estudio fue determinar la concentración inhibitoria mínima (CIM) y la concentración bactericida mínima (CBM) a la rifampicina y al cloranfenicol en aislamientos de S. pneumoniae pertenecientes a un grupo recolectado entre 1994 a 1996 de niños menores de 5 años con infección sistémica y meningitis. Se estudiaron 107 aislamientos, 60 de ellos resistentes a penicilina y 47 sensibles, 53 de los cuales fueron aislamientos de LCR. La CIM y la CBM se realizaron de acuerdo con las recomendaciones de la NCCLS; se utilizó S. pneumoniae ATCC 49619 como control. Se consideraron como sensibles al cloranfenicol los aislamientos con CIM=4 µg/ml y resistentes, con CIM=8 µg/ml; sensibles a rifampicina con CIM=1 µg/ml y resistentes con CIM=4 µg/ml. La CBM se determinó con la menor concentración del antibiótico que inhibió el crecimiento del 99,9 por ciento del inóculo. Se encontró resistencia al cloranfenicol en 20,5 por ciento de los 107 aislamientos estudiados. En el grupo resistente a la penicilina, 28 por ciento fue resistente al cloranfenicol y 11 por ciento en el grupo sensible a la penicilina. La CBM para el cloranfenicol fue >4 µg/ml en 28 por ciento de los aislamientos sensibles a la penicilina y en 60 por ciento de los resistentes. No se encontraron aislamientos resistentes a la rifampicina; sin embargo, 2 aislamientos mostraron CBM>1 µg/ml y una CBM=16 µg/ml. Los aislamientos de LCR presentaron la CIM y la CBM más altas que el grupo total de aislamientos. Los datos sugieren que en Colombia el cloranfenicol no se debe usar como terapia empírica para infecciones invasivas por neumococo en niños menores de 5 años. La rifampicina combinada con otros antibióticos en el tratamiento de estas infecciones puede ser una alternativa. Es necesario realizar otros estudios para conocer el significado que tendrían los bajos niveles de CBM a la rifampcina encontrados en algunos de los aislamientos, para la eficiacia de estos tratamientos.

Febre tifóide: recaída por resistência antimicrobiana. Relato de caso / Typhoid fever: relapse due to antimicrobial resistance. Case report

Relatamos pela primeira vez na Amazônia Brasileira um paciente com febre tifóide, com resistência clínica e laboratorial ao cloranfenicol, droga de escolha para esta doença em nossa regiäo. A recaída foi observada no 7° dia após o término do tratamento e a paciente foi tratada com ciprofloxacina

Antimicrobial resistance among invasive Haemophilus influenzae strains: results of a Brazilian study carried out from 1996 through 2000

A total of 1712 strains of Haemophilus influenzae isolated from patients with invasive diseases were obtained from ten Brazilian states from 1996 to 2000. ß-Lactamase production was assessed and the minimum inhibitory concentrations (MIC) of ampicillin, chloramphenicol, ceftriaxone and rifampin were determined using a method for broth microdilution of Haemophilus test medium. The prevalence of strains producing ß-lactamase ranged from 6.6 to 57.7 percent, with an overall prevalence of 18.4 percent. High frequency of ß-lactamase-mediated ampicillin resistance was observed in Distrito Federal (25 percent), Säo Paulo (21.7 percent) and Paraná (18.5 percent). Of the 1712 strains analyzed, none was ß-lactamase negative, ampicillin resistant. A total of 16.8 percent of the strains were resistant to chloramphenicol, and 13.8 percent of these also presented resistance to ampicillin, and only 3.0 percent were resistant to chloramphenicol alone. All strains were susceptible to ceftriaxone and rifampin and the MIC90 were 0.015 æg/ml and 0.25 æg/ml, respectively. Ceftriaxone is the drug of choice for empirical treatment of bacterial meningitis in pediatric patients who have not been screened for drug susceptibility. The emergence of drug resistance is a serious challenge for the management of invasive H. influenzae disease, which emphasizes the fundamental role of laboratory-based surveillance for antimicrobial resistance

Caracterización molecular de mecanismos de resistencia a cloranfenicol en cepas de shigella flexneri aisladas en niños chilenos con diarrea aguda / Molecular characterization of resistance mechanisms to chloramphenicol in shigella flexneri strains isolated from chilean children with acute diarrhea

Background: Chloramphenicol is one of the therapeutic options for shigellosis, but resistance to this antimicrobial is increasing. Aim: To characterize molecular mechanisms conferring resistance to chloramphenicol (CmR) in Shigella flexneri strains isolated from Chilean children with acute diarrhea. Material and methods: Thirty one Shigella filexneri strains, including 22 with the CmR phenotype were analyzed. Strains were tested for antimicrobial susceptibility by plate dilution and for the presence of an internal fragment of the cat gene encoding for chloramphenicol o-acetyl-transferase, by polymerase chain reaction and Southern blot analysis. Results: All CmR strains had a minimal inhibitory concentration over 64 µg/ml and amplified the internal fragment of the cat gene. Southern blot analyses indicated that this gene was located in the bacterial chromosome. Conclusions: Resistance to chloramphenicol in this group of Shigella flexneri strains was mediated by a chromosomally located cat gene

Streptococcus pneumoniae: evolución de la resistencia a los antimicrobianos en un hospital de niños de Córdoba, Argentina / Streptococcus pneumoniae: evolution of antibiotic resistance in a pediatric hospital in Córdoba, Argentina

The wide variety of prevalence of antimicrobial resistant Streptococcus pneumoniae in different countries confirms the importance of determining local patterns of resistance. From 1992 to 2000, we studied the pattern of antimicrobial resistance in S. pneumoniae and its evolution along the years, using 468 strains isolated in the Hospital de Niños de Córdoba. A total of 177 isolates (37.8) were not susceptible to penicillin, with 19 intermediate and 18.8 resistant strains. High and intermediate resistance levels to cefotaxime were 4.9 and 10.9, respectively. Decreased susceptibility to trimethoprim/sulfamethoxazole (TMS), erythromycin, chloramphenicol, and rifampin was found in 194 isolates (41.5), 32 (6.8), 13 (2.8) and 3 (0.6), respectively. No isolates resistant to vancomycin were detected. The most commonly combined resistance patterns were: penicillin/TMS (35.6) and penicillin/TMS/cefotaxime (11.8). This study highlights the increased rate of drug resistant S. pneumoniae during the last years, and the importance of antimicrobial resistance surveillance of adequate empirical therapy involving local and regional susceptibility patterns.

Streptococcus pneumoniae: evolución de la resistencia a los antimicrobianos en un hospital de niños de Córdoba, Argentina / Streptococcus pneumoniae: evolution of antibiotic resistance in a pediatric hospital in Córdoba, Argentina

The wide variety of prevalence of antimicrobial resistant Streptococcus pneumoniae in different countries confirms the importance of determining local patterns of resistance. From 1992 to 2000, we studied the pattern of antimicrobial resistance in S. pneumoniae and its evolution along the years, using 468 strains isolated in the Hospital de Niños de Córdoba. A total of 177 isolates (37.8) were not susceptible to penicillin, with 19 intermediate and 18.8 resistant strains. High and intermediate resistance levels to cefotaxime were 4.9 and 10.9, respectively. Decreased susceptibility to trimethoprim/sulfamethoxazole (TMS), erythromycin, chloramphenicol, and rifampin was found in 194 isolates (41.5), 32 (6.8), 13 (2.8) and 3 (0.6), respectively. No isolates resistant to vancomycin were detected. The most commonly combined resistance patterns were: penicillin/TMS (35.6) and penicillin/TMS/cefotaxime (11.8). This study highlights the increased rate of drug resistant S. pneumoniae during the last years, and the importance of antimicrobial resistance surveillance of adequate empirical therapy involving local and regional susceptibility patterns.(AU)

Estudo do perfil de resistência de 626 cepas de Staphylococcus aureus isolados de 25 hospitais brasileiros entre setembro de 1995 e junho de 1997 / Study of the resistance profile of 626 strains of staphylococcus aureus isolated in 25 Brazilian Hospitals from September/95 do June/97

O objetivo deste estudo foi avaliar o perfil de resistência de cepas de Staphylococcus aureus isoladas de várias regiöes do Brasil. Foram estudadas 626 cepas provenientes de 25 hospitais, como mais de 250 leitos, localizados em 14 estados. O antibiograma foi realizado do método de difusäo de discos (kirby-Bauer), utilizando 12 antibióticos. As cepas oxacilino-resistentes (Orsa) foram também testadas empregando a técnica de microdiluiçäo em caldo por meio do Sistema MicroScan-Baxter Inc. Das 626 cepas enviadas, 388 foram oxacilino-sensíveis (Ossa) e 238 Orsa. Dentre as cepas Ossa, os percentuais de resistência encontrados foram: penicilina (87,1 por cento), eritromicina (16,2), tetraciclina (15,7), lincomicina (7,5), cloranfenicol (3,1), rifampicina (1,6), sulfametoxazol (SUT) (0,8 por cento), netilmicina (0,5) e ciprofloxacina (0,03). Dentre as cepas Orsa, 99,6 foram resistentes à eritromicina, lincomicina e tetraciclina, 96,2 ao SUT, 2 por cento à ciprofloxacina, 73,1 ao cloranfenicol, 71 à netilmicina e 22,7 à rifampicina. Todas as amostras foram sensíveis à vancomicina. As cepas de S. aureus isoladas no Brasil apresentam níveis mais elevados de resistência que os relatos em outros países. Ciprofloxacina, eritromicina, tetraciclina, lincomicina e SUT foram os antibióticos que apresentaram os mais elevados níveis de resistência. As elevadas taxas de resistência poderiam ser conseqüencia do uso em larga escala de antibióticos, que teria contribuído para a seleçäo de clones mutirresistentes

Epidemiology of haemophilus influenzae invasive disease in Jamaica, 1990-1993

Haemophilus influenzae (H influenzae) invasive disease was studied retrospectively over a four-year period in children admitted to the Bustamante Hospital for Children in Kingston, Jamaica. A total of 86cases were identified. The mean estimated annual incidence of H influenzae invasive disease in Kingston and St. Andrew was 39 per 100,000 children under 5 years of age. The majority (77percent) of cases were in the under 2-year age group. A distinct seasonal pattern was noted, with a significantly higher proportion of patients (57-73percent) presenting in the cooler months. Meningitis was the most common clinical diagnosis, accounting for 76percent of the cases. Poor outcome was demonstrated in 21.5percent of patients with meningitis. Sensitivity testing of H influenzae isolates revealed a resistance rate of 26percent for ampicillin and 7percent for chloramphenicol. The epidemiological findings in this study provide reasonable guidelines for empiric antibiotic therapy and also support the need to seriously consider vaccine prophylaxis in Jamaican children.(Au)