Antibiotic resistance of Enterococcus faecalis from persistent endodontic infections / Resistencia antibiótica de Enterococcus faecalis provenientes de infecciones endodónticas persistentes

Enterococci are important nosocomial pathogens due to their intrinsic multiresistance and the acquisition of new antibiotic resistance genes (ARG). Enterococcus faecalis has been shown to be one of the main pathogens in persistent endodontic infections, therefore, the main objective of this study was to evaluate the phenotype and resistance genotype of strains of E. faecalis isolated from teeth with persistent endodontic lesions, to the most commonly prescribed antibiotics in dentistry. Thirteen strains of E. faecalis of different pulsotype were analyzed to evaluate the susceptibility to antibiotics, amoxicillin, amoxicillin/clavulanic acid, tetracycline, erythromycin and metronidazole, using the Epsilometer test (E- test) and the presence of beta-lactamases with nitrocefin test. Finally, the detection of ARG was performed with a molecular polymerase chain reaction (PCR) technique and confirmed by the sequencing of the amplification products. Fisher's exact test was used, using 95 % confidence. Regarding the phenotype of resistance, the evaluated strains, independent of the pulsotype, were totally resistant to the action of metronidazole. Antibiotics with higher minimum inhibitory concentration (MIC) after metronidazole include tetracycline and erythromycin. In contrast, lower MIC are applied to the combination of amoxicillin with clavulanic acid. The nitrocefin test was positive only in one strain. Genotypically, two genetically distant strains isolated from a single patient, presented a genotype of resistance to erythromycin, determined by the presence of the ermB gene. No statistically significant relationship was found between phenotypic resistance and the presence of ARG in relation to erythromycin (p> 0.05). It was concluded that isolates of E. faecalis from persistent endodontic infections showed phenotypes of resistance to several antimicrobial agents, all of which were susceptible to amoxicillin/clavulanic acid. Periodic evaluation of susceptibility to antibiotics is suggested as an important practice for the surveillance of antibiotic resistance in oral strains.

Los enterococos son importantes patógenos nosocomiales debido a su multi resistencia intrínseca y la adquisición de nuevos genes de resistencia a los antibióticos (ARG). Enterococcus faecalis es uno de los principales patógenos en infecciones endodónticas persistentes, por lo tanto, el objetivo principal de este estudio fue evaluar el fenotipo y el genotipo de resistencia de cepas de E. faecalis aisladas de dientes con lesiones endodóncicas persistentes, a los antibióticos comúnmente recetados en odontología. Se analizaron 13 cepas de E. faecalis de diferentes pulsotipos para evaluar la susceptibilidad a los antibióticos, amoxicilina, amoxicilina / ácido clavulánico, tetraciclina, eritromicina y metronidazol, utilizando la prueba de Epsilometría (E-test) y la presencia de beta-lactamasas con prueba de nitrocefina. Finalmente, la detección de ARG se realizó con una técnica molecular de reacción en cadena de la polimerasa (PCR) y se confirmó mediante la secuenciación de los productos de amplificación. Se utilizó la prueba exacta de Fisher, con un 95 % de confianza. En cuanto al fenotipo de resistencia, las cepas evaluadas, independientes del pulsotipo, fueron totalmente resistentes a la acción del metronidazol. Los antibióticos con los valores más altos de concentración mínima inibitoria (CMI) después del metronidazol incluyen tetraciclina y eritromicina. En contraste, las CMI mas bajas se aplican a la combinación de amoxicilina con ácido clavulánico. La prueba de nitrocefina fue positiva solo en una cepa. Genotípicamente, dos cepas distantes genéticamente, aisladas de un mismo paciente fueron positivas para el gen ermB. No se encontró una relación estadísticamente significativa entre la resistencia fenotípica y la presencia de ARG en relación con la eritromicina (p> 0,05). Se concluyó que los aislamientos de E. faecalis de infecciones endodónticas persistentes mostraron fenotipos de resistencia a varios agentes antimicrobianos, todos los cuales fueron susceptibles a amoxicilina / ácido clavulánico. Se sugiere una evaluación periódica de la susceptibilidad a los antibióticos como una práctica importante para la vigilancia de la resistencia a los antibióticos en las cepas orales.

Evaluation of restoration of sensitivities of resistant Staphylococcus aureus isolates by using cefuroxime and clavulanic acid in combination

The present study was planned to observe the activity of cefuroxime, a second generation cephalosporin after combining it with a beta-lactamase inhibitor calvulanic acid. The study was conducted to evaluate the restoration or increase in sensitivity of beta-lactamase producing isolates of Staphylococcus aureus. Staphylococcus aureus were identified by standard procedures. For beta-lactamase detection chromogenic Nitrocefin impregnated sticks were used. The sensitivity of the bacteria to the antibiotic disks was measured by disk diffusion method using standard zone diameter criteria given by National Committee of Clinical Laboratory Standards. The disks of cefuroxime with clavulanic acid had developed larger zones of inhibition. The activity of cefuroxime against Staphylococcus aureus was significantly increased by clavulanic acid. Clavulanic acid if used in combination with cefuroxime, can improve the antimicrobial activity of cefuroxime against beta-lactamase producing Staphylococcus aureus

Sensitivity pattern of gram negative bacilli to three beta-lactam/beta-lactamase inhibitor combinations using the automated API system.

PURPOSE: To evaluate the spectrum of activity of three beta-lactamase inhibitors such as amoxicillin/ clavulanic acid, ticarcillin/ clavulanic acid and piperacillin/ tazobactam in comparison to cephalosporins against gram negative bacilli. METHODS: Gram-negative bacilli isolated from the clinical specimens received in the laboratory were included in the study. Using the API system (bioMiotarieux) during a one-year period, a total of 1,252 Enterobacteriaceae and 385 non-fermenters were evaluated. RESULTS: The percentage resistance of the Enterobacteriaceae isolates was 82.92% to amoxicillin/ clavulanic acid, 58.22% to ticarcillin/clavulanic acid and 22.44% to piperacillin/tazobactam respectively. Pseudomonas aeruginosa showed resistance of 96% to ticarcillin/ clavulanic acid and 61% to piperacillin/ tazobactam and Acinetobacter baumannii showed 49% resistance to ticarcillin/ clavulanic acid and 77% resistance to piperacillin/ tazobactam respectively. The isolates exhibited high resistance to all the generations of cephalosporins and the other groups of antibiotics except carbapenems. CONCLUSIONS: Piperacillin/tazobactam was found to be the most active combination of the three against Enterobacteriaceae and Pseudomonas spp. and ticarcillin/clavulanic acid against Acinetobacter spp. and Stenotrophomonas maltophilia.

Occurrence of extended-spectrum beta-lactamases in Enterobacteriaceae isolated from hospitalized patients in Curitiba, southern Brazil

Production of extended-spectrum beta-lactamases (ESBL) by enterobacteria is an important resistance mechanism against antimicrobial beta-lactamics. We tested 498 bacterial strains isolated from two tertiary-care teaching hospitals for ESBL production, using screening breakpoints for aztreonam and third generation cephalosporins, according to CLSI recommendations. Among these isolates, 155 were positive for the ESBL screening test, and 121 (78 percent) were confirmed by the clavulanic acid combination disk method. We found a high frequency of ESBL (24 percent) among Enterobacteriaceae, with a frequency of 57.4 percent for Klebsiella pneumoniae, 21.4 percent for Klebsiella oxytoca, and 7.2 percent for E. coli. In other members of Enterobacteriaceae, non-Klebsiella and non-E. coli, the prevalence was 21.6 percent. Ceftriaxone and cefotaxime showed a higher sensitivity in the screening test (99.2 percent) when compared to ceftazidime, aztreonam and cefpodoxime. However, cefotaxime/cefotaxime plus clavulanic acid showed a higher sensitivity in the confirmatory test (96.7 percent).

AmpC beta-lactamase producing bacterial isolates from Kolkata hospital.

BACKGROUND AND OBJECTIVE: The widespread use of beta-lactam antibiotics has lead to the development of resistance to this group of antibiotics in bacterial pathogens due to beta-lactamase production. Information on such pathogens is not available from eastern region of India. This study was undertaken to determine the AmpC beta-lactamase production in pathogens isolated from hospitalized patients in Kolkata. METHODS: Non-repeat clinical isolates (284) from pus, urine, sputum and other clinical specimens of hospitalized patients were taken. Disk agar diffusion (DAD) and minimum inhibitory concentration (MIC) with different beta-lactam antibiotics, and double disc synergy test (DDST) with clavulanic acid and sulbactam were done. Disk antagonism test (DAT) and three-dimensional extract test (TDET) were conducted for phenotypic confirmation of AmpC and inducible AmpC beta-lactamase production. Nitrocefin spot test and microiodometric assay of beta-lactamase were also performed. RESULTS: Twenty seven isolates were found to be resistant to cefoxitin, a alpha-methoxy-beta-lactam. Of these, 19 were observed to be AmpC beta-lactamase producers and 4 were inducible AmpC beta- lactamase producers by DDST, DAT and TDET. Remaining 4 were non AmpC beta-lactamase producers. Of the 23 AmpC beta-lactamase producers, the distribution of different species was as follows: Escherichia coli 11 (47.8%), Pseudomonas aeruginosa 4 (17.3%) Klebsiella pneumoniae 3 (13%), and Klebsiella aeruginosa 1 (4.3%). INTERPRETATION AND CONCLUSION: Our finding showed 6.7 per cent AmpC beta-lactamase and 1.4 per cent inducible AmpC beta-lactamase producing clinical isolates from Kolkata. AmpC beta-lactamase producing bacterial pathogens may cause a major therapeutic failure if not detected and reported in time.

Prevalência de Escherichia coli, Klebsiella pneumoniae e Klebsiella oxytoca produtoras de beta-lactamases de espectro estendido (ESBL) em pacientes do Hospital Divina Providência, Porto Alegre, RS / Prevalence of Escherichia coli, Klebsiella pneumoniae and Klebsiella oxytoca producers Extended-Spectrum Beta-Lactamases (ESBL) in patients from Divina Providencia Hospital, Porto Alegre, RS

As beta-lactamases de Amplo Espectro (ESBL) produzidas, principalmente, por Klebsiella sp. e E. coli, constituem um problema cada vez mais comum e com sérias conseqüências terapêuticas. As ESBL säo enzimas que conferem resistência às Cefalosporinas de amplo espectro, como a Cefotaxina, Ceftriaxona e Ceftazidima, e ao monobactâmico Aztreonam. Foram estudadas 88 amostras de isolados clínicos, provenientes de pacientes internados no Hospital Divina Providência, de Porto Alegre, Rio Grande do Sul, durante o período de abril de 2001 a junho de 2002. Realizou-se o teste de triagem e o teste confirmatório através dos critérios padronizados pelo National Comittee for Clinical Laboratory Standards (NCCLS). Os testes confirmatórios da produçäo destas enzimas foram executadas pela técnica da adiçäo de ácido clavulânico ao disco de Ceftazidima. Foram caracterizadas no teste de triagem , 9 (10,2 porcento) amostras suspeitas de serem produtoras de ESBL, sendo que 4 (4,5 porcento) foram caracterizadas como produtoras de ESBL

Uso terapeutico de amoxicilina-acido clavulanico en la enfermedad periodontal / Therapeutic use of amoxicillin-clavulanic acid in periodontal disease

En el presente trabajo se estudia la combinación amoxicilina/ßcido clavulßnico como agente que puede ser eficiente en la terapia periodontal, basßndose fundamentalmente en la revisión bibliogrßfica de comunicaciones cientÝficas; para ello se considera su efectividad clÝnica en las diferentes patologÝas periodontales, las pautas referentes a posologÝa y administración, todo lo cual contribuirß a usarlo en una forma racional, con criterio equilibrado en la terapÚutica de las periodontopatÝas

Sensibilidade aos antimicrobianos de amostras Pseudomonas aeruginosa e acinetobacter spp: dados do programa de vigilância RESISTNET Brasil / Antimicrobial susceptibility of pseudomonas aeruginosa e acinetobacter spp: RESISTNET Brasil surveillance program

O programa RESISTNET é um estudo de vigilância de resistência bacteriana a diversos antimicrobianos. Trata-se de um projeto latino-americano iniciado em abril de 1998. No final de 1999, este programa no Brasil passou a denominar-se RESISTNET Brasil. Um dos principais objetivos deste estudo é gerar dados pontuais, atualizados e confiáveis da atual situaçäo da resistência bacteriana a diversos antimicrobianos. Neste trabalho, apresentamos os resultados obtidos durante 12 meses (janeiro a dezembro de 1999), num total de 705 amostras bacterianas, respectivamente 524 amostras de Pseudomonas aeruginosa e 181 amostras de Acinobacter spp, isoladas de diversos materiais clínicos provenientes de pacientes da comunidade (167 amostras) e hospitalizados (538 amostras) de 13 centros em seis cidades brasileiras (Säo Paulo, Porto Alegre, Curitiba, Brasília, Salvador e Fortaleza). Os isolados foram testados pelo método da difuçäo do disco, de acordo com as normas estipuladas pelo NCCLS (11), aos seguintes antimicrobianos: aztreonam, amicacina, cefepima, ceftazidima, cefoperazona, colistina, ciprofloxacina, gentamicina, imipenem, piperacilina,ticarcilina/ácido clavulânico, amplicilina/sulbactam e tobramicina, Em relaçäo a Pseudonomas aeruginosa, os antimicrobianos mais ativos foram, respectivamente: colistina, imipenem, ceftazidima, cefepima e ciprofloxacina (taxas de sensibilidade de 100 por cento, 78,6 por cento, 77 por cento, 67,6 por cento e 66 por cento). Para Acinobacter spp, os antimicrobianos mais ativos foram: colistina, imipenem, amplicilina/sulbactram e trobamicina (taxas de sensibilidade de 100 por cento, 98,9 por cento, 82,8 por cento e 55,6 por cento respectivamente). As amostras de origem hospitalar apresentaram índices maiores de resistência quando comparadas com as amostras provenientes da comunidade. Os resultados deste levantamento mostram a importância de estudos de resistência aos microbianos, pois estes bacilos Gram negativos näo fermentadores, além de serem responsáveis por diversas infecçöes humanas, mostram significativas taxas de resistência a diversos antimicrobianos

In vitro antimicrobial activity of piperacillin/tazobactam in comparison with other broad-spectrum ß-Lactams

Combinig tazobactam, a ß-lactamase inhibitor, with the ureidopenicillin, piperacillin, successfully restores the activity of piperacillin against ß-lactamase producing bacteria. Thus, piperacillin/tazobactam is highly active against most clinically important species of Gram-negative and Gram-positive bacteria, including anaerobes. We evaluated the in vitro activity of piperacillin/tazobactam against clinical isolates from a tertiary university hospital located in Säo Paulo, Brazil. Its activity was compared to the ticarcillin/ clavulanic acid, ampicillin/sulbactam, ceftazidimeceftriaxone, cefotaxime, cefoxitin, aztreonam and imipenem against 820 isolates (608 Gram-negative and 212 Gram-positive) collected from hospitalized patients in 1999. The most frequent species tested were Pseudomonas aeruginosa (168/20 por cento), Escherichia coli (139/17 por cento), Acinetobacter spp (131/16 porcento), and Staphylococcus aureus (76/9 por cento). Of the isolates studied, 30 por cento were from the blodstream, 16 porcento from the lower respiratory tract, and 11 por cento from surgical wounds or soft tissue. The isolates were susceptibility tested by the broth microdilution method according to NCCLS procedures. The isolates tested were highly resistant to most antimicrobial agents evaluated. Imipenem resistance was not verified among Enterobacteriaceae, and piperacillin/tazobactam was the second most active ß-lactam against this group of bacteria (80.0 por cento susceptibility). Extended-spectrum ß-lactamase production was very high among E. coli (approximately 20 por cento) and KLebsiella pneumoniae (approximately 40 por cento). Imipenem was uniformly active against these species (100 por cento susceptibility) and piperacillin/tazobactam was the second most active compound inhibiting 84.4 por cento of isolates. Pseudomonas aeruginosa was highly resistant to all ß-lactams evaluated and piperacillin/tazobactam was the most active compound against this species. Our results demonstrate an extremely high level of antimicrobial resistance in the hospital evaluated, especially among non-enteric Gram-negative bacilli. Due to this high level of resistence, piperacillin/tazobactam represents an important ciontribution to the treatment of nosocomial infections...

Susceptibility of clinical isolates of Bacteroides fragilis group strains to cefoxitin, cefoperazone and ticarcillin/clavulanate

A total of 40 strains of the B. fragilis group was isolated from clinical specimens in two hospital centers in Fortaleza from 1993 to 1997. The most frequently isolated species was Bacteroides fragilis (19 strains) and most isolates came from intra-abdominal and wound infections. The susceptibility profile was traced for cefoxitin, cefoperazone and ticarcillin-clavulanate by using the agar dilution reference method. All isolates were susceptible to ticarcillin-clavulanate (128/2mug/ml). Resistance rates of 15 and 70 percent were detected to cefoxitin (64mug/ml) and cefoperazone (64mug/ml), respectively. Such regional results permit a better orientation in choosing this group of antibiotics for prophylaxis and therapy especially in relation to cefoxitin, which is frequently used in the hospital centers studied.