Recovery of aerobic and anaerobic bacteria from patients with acute appendicitis using blood culture bottles / Recuperación de bacterias aerobias y anaerobias de pacientes con apendicitis aguda mediante botellas de hemocultivo

Introduction: Acute appendicitis is the first cause of acute abdomen, however, there is a little information about the associated bacteria and its sensibility profile. Objetive: To identify and to determine the resistance pattern of aerobic and anaerobic bacteria isolated in periapendicular fluid cultures taken in patients with acute appendicitis and to establish the proportions of isolates according to the clinical phase. Materials and methods: A descriptive and prospective study was undertaken at the Hospital Universitario de San José (Bogotá, Colombia) of patients older than sixteen years of age, undergoing an open appendectomy. A sample of periappendiceal fluid was taken, which was deposited directly into aerobic and anaerobic blood culture bottles. Results: One hundred and fifty-four patients were included. The overall positivity of cultures was 87% (n=1344); 77% (n=118) for aerobes and 51% (n=79) for anaerobes. The proportion of positive cultures was lower in the uncomplicated appendicitis cases as compared to the complicated ones (80% (66/83) vs. 95%(67/71), p = 0.003). The microorganisms isolated most frequently were: Escherichia coli (53%) (n=84); Bacteroides spp. (25%) (n=25); Propionibacterium acnes (21%) (n=21); coagulase negative Staphylococci (17%) (n=27); Enterococcus spp. (11%) (n=15), and Fusobacterium spp. (11%) (n=11). The sensitivity of E. coli to ampicillin/sulbactam was 30%. The sensitivity of Bacteroides spp. to clindamycin and ampicillin/sulbactam was 91%. All anaerobe isolates were sensitive to piperacillin/tazobactam, ertapenem, meropenem and metronidazole. Conclusions: Intraoperative cultures in acute appendicits are relevant in order to determine the local epidemiological pattern and to establish prophylactic and therapeutic antibiotics for this pathology; direct inoculation in blood culture bottles allows a high recovery of microorganisms.

Introduccción. La apendicitis aguda es la primera causa de abdomen agudo; sin embargo, poco se conoce sobre las bacterias asociadas y su perfil de sensibilidad. Objetivo. Identificar y determinar el patrón de resistencia de las bacterias aerobias y anaerobias aisladas en cultivo de líquido periapendicular tomado de los pacientes con apendicitis aguda, y establecer la proporción de bacterias según la fase clínica. Materiales y métodos. Se llevó a cabo un estudio descriptivo y prospectivo en el Hospital Universitario de San José de Bogotá (Colombia), en pacientes mayores de 16 años sometidos a apendicectomía abierta. Se tomaron muestras de líquido periapendicular, las cuales se sembraron directamente en botellas de hemocultivos para aerobios y anaerobios. Resultados. Se incluyeron 154 pacientes. Del total de cultivos, el 87 % (n=134) fueron positivos: 77 % (n=118) para aerobios y 51 % (n=79) para anaerobios. La proporción de cultivos positivos fue inferior en los casos de apendicitis no complicada, en comparación con aquellos de apendicitis complicada (80 % (66/83) Vs. 95 % (67/71); p=0,003). Los microorganismos aislados con mayor frecuencia fueron: Escherichia coli (53 %) (n=84), Bacteroides sp. (25 %) (n=25), Propionibacterium acnes (21 %) (n=21), Staphylococci coagulasa negativo (17 %) (n=27), Enterococcus sp. (10 %) (n=15) y Fusobacterium sp. (11 %) (n=11). La sensibilidad de E. coli a la amplicilina sulbactam fue de 30 %. La sensibilidad de Bacteroides spp. a la clindamicina y la ampicilina sulbactam fue de 91 %. El 100 % de los anaerobios fueron sensibles a piperacilina tazobactam, ertapenem, meropenem y metronidazol. Conclusiones. Los cultivos intraoperatorios son pertinentes en la apendicitis para determinar el patrón epidemiológico local, y establecer los antibióticos profilácticos y terapéuticos para esta enfermedad. Su siembra directa en botellas de hemocultivo permite una gran recuperación de microorganismos.

Is Antimicrobial Photodynamic Therapy Effective for Microbial Load Reduction in Peri-implantitis Treatment? A Systematic Review and Meta-Analysis.

The systematic review and meta-analysis were undertaken to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) in the microbiological alteration beneficial to peri-implantitis treatment. This study is registered with PROSPERO, number CRD42017064215. Bibliographic databases including Cochrane Library, Web of Science, Scopus and PubMed were searched from inception to 8 January 2017. The search strategy was assembled from the following MeSH Terms: "Photochemotherapy," "Dental Implants" and "Peri-Implantitis." Unspecific free-text words and related terms were also included. The Cochrane Collaboration's tool was used to evaluate the risk of bias of included studies. The random-effect model was chosen, and heterogeneity was evaluated using the I2 test. Three studies met the inclusion criteria. Meta-analysis demonstrated an association between aPDT and reduction in viable bacteria counts for: Aggregatibacter actinomycetemcomitans (OR = 1.31; confidence interval = 1.13, 1.49; P < 0.00001), Porphyromonas gingivalis (OR = 4.08; confidence interval = 3.22, 4.94; P < 0.00001) and Prevotella intermedia (OR = 1.66; confidence interval = 1.06, 2.26; P < 0.00001). A aPDT appears to be effective in bacterial load reduction in peri-implantitis and has a positive potential as an alternative therapy for peri-implantitis.

Occurrence and antimicrobial susceptibility of Porphyromonas spp. and Fusobacterium spp. in dogs with and without periodontitis.

The occurrence of Porphyromonas gulae, Porphyromonas macacae, Fusobacterium nucleatum and Fusobacterium canifelinum in subgingival plaque from dogs with and without periodontitis as well as their antimicrobial susceptibility were evaluated. From 50 dogs with periodontitis were identified 38 P. gulae, 8 P. macacae, 26 F. nucleatum and 15 F. canifelinum, and from 50 dogs without periodontitis were identified 15 P. gulae, 12 F. nucleatum and 11 F. canifelinum. All strains were susceptible to most of the antibiotics tested, however, different resistance rates to clarithromycin, erythromycin and metronidazole among strains were observed. The role of P. gulae, P. macacae, F. nucleatum and F. canifelinum in periodontal disease of household pets needs to be defined to a better prevention and treatment of the canine periodontitis.

Adjunctive azithromycin in the treatment of aggressive periodontitis: microbiological findings of a 12-month randomized clinical trial.

OBJECTIVES: To compare the subgingival microbiological outcomes of azithromycin or placebo as adjuncts to scaling and root planing (SRP) in the treatment of aggressive periodontitis (AgP), and to secondarily evaluate the microbiological effect of supragingival scaling in AgP patients. METHODS: Twenty-four AgP subjects 13-26 years of age received a 15-day programme of supragingival scaling (SC) and were then randomly assigned to SRP with systemic azithromycin or placebo. Subgingival samples were taken with sterile paper points at baseline, 15 days after SC, and at 3, 6 and 12 months following SRP. Microbiological analysis was performed by the checkerboard DNA-DNA hybridization. RESULTS: Changes in bacterial levels from baseline to 15 days after SC were similar in the 2 groups. When subjects were analysed as a single group, significant reductions after SC were observed for Actinomyces gerencseriae, Capnocytophaga ochracea, and Treponema denticola. During the 12-month follow-up, levels of most of the bacteria decreased in both groups in a similar pattern. For instance, Actinomyces israelli, Veillonella parvula, Streptococcus gordonii, C. ochracea, Eikenella corrodens, Eubacterium nodatum, Fusobacterium periodonticum and Fusobacterium nucleatum ssp. polymorphum decreased significantly within the groups. CONCLUSIONS: Azithromycin was ineffective in lowering the subgingival levels of important putative periodontal pathogens in young AgP subjects compared to placebo. CLINICAL SIGNIFICANCE: Scaling and root planing with adjunctive systemic azithromycin provides little additional benefit compared to placebo in reductions of major subgingival periodontal pathogens.

Analysis of the antimicrobial susceptibility of anaerobic bacteria isolated from endodontic infections in Brazil during a period of nine years.

INTRODUCTION: The purpose of this study was to analyze the susceptibility of some anaerobic species isolated from a Brazilian population at different periods of time by determining a pattern of development of resistance to frequently prescribed antibiotics in endodontics. METHODS: Root canal samples were collected from infected teeth at different periods of time (2000-2002, 2003-2005, and 2007-2008) and microbiologically identified with conventional culture techniques. The susceptibility of Prevotella intermedia/nigrescens, P. oralis, Fusobacterium nucleatum, and P. micra isolated strains was determined by the minimum inhibitory concentration (MIC) of amoxicillin, amoxicillin + clavulanate, benzylpenicillin, clindamycin, erythromycin, and metronidazole by using the E-test method. RESULTS: Amoxicillin and amoxicillin + clavulanate were effective against the majority of species at the different periods of study. Overall, there were low statistical differences regarding the microbial susceptibility between the experimental periods. However, an increase in the anaerobic resistance to penicillin G and clindamycin was observed. Resistance to erythromycin was observed in all species, and there were statistically significant differences between 2000-2002 and 2003-2005 periods for F. nucleatum (P < .05) and between 2003-2005 and 2007-2008 periods for P. intermedia/nigrescens and P. oralis (P < .05). CONCLUSIONS: The antimicrobial resistance of anaerobes isolated from primary endodontic infections showed an increase throughout a period of time regarding a specific Brazilian population.

Influence of local tetracycline on the microbiota of alveolar osteitis in rats.

The aim of the present study was to evaluate the effects of local tetracycline on the occurrence of alveolar osteitis in rats, and on the microbiota associated to this infection. Forty Wistar rats were randomly assigned to 4 groups (n=10): I - the rats had the maxillary right incisor extracted and the alveolar wound did not receive any treatment; II - adrenaline and Ringer-PRAS were introduced into the alveolar wound; III - the alveolar wound was irrigated with sterile saline; and IV - the alveolar wound was irrigated with an aqueous solution of tetracycline. Microbial samples from the alveolar wounds were collected 2 days after surgery and inoculated on blood agar (with and without 8 microg/mL of tetracycline) and other selective media, and were incubated in either aerobiosis or anaerobiosis at 37 degrees C, for 2 to 14 days. It was verified that tetracycline reduced the occurrence of alveolar osteitis in the rats and caused significant changes in the microbiota of the surgical sites, decreasing the number of anaerobes and increasing the participation of tetracycline-resistant and multi-resistant microorganisms.

Influence of local tetracycline on the microbiota of alveolar osteitis in rats

The aim of the present study was to evaluate the effects of local tetracycline on the occurrence of alveolar osteitis in rats, and on the microbiota associated to this infection. Forty Wistar rats were randomly assigned to 4 groups (n=10): I - the rats had the maxillary right incisor extracted and the alveolar wound did not receive any treatment; II - adrenaline and Ringer-PRAS were introduced into the alveolar wound; III - the alveolar wound was irrigated with sterile saline; and IV - the alveolar wound was irrigated with an aqueous solution of tetracycline. Microbial samples from the alveolar wounds were collected 2 days after surgery and inoculated on blood agar (with and without 8 µg/mL of tetracycline) and other selective media, and were incubated in either aerobiosis or anaerobiosis at 37ºC, for 2 to 14 days. It was verified that tetracycline reduced the occurrence of alveolar osteitis in the rats and caused significant changes in the microbiota of the surgical sites, decreasing the number of anaerobes and increasing the participation of tetracycline-resistant and multi-resistant microorganisms.

O objetivo do presente estudo foi avaliar os efeitos do uso tópico de tetraciclina sobre a ocorrência de alveolite em ratos e sobre a microbiota a ela associada. Quarenta ratos foram divididos, ao acaso, em 4 grupos (n=10): grupo I, realizou-se somente a extração do incisivo superior direito e a ferida alveolar não recebeu nenhum tratamento; grupo II, além da extração dental, soluções de adrenalina e Ringer-PRAS foram introduzidas no interior do alvéolo; grupo III, a ferida alveolar foi irrigada com solução salina estéril; grupo IV, a ferida alveolar foi irrigada com solução aquosa de cloridrato de tetraciclina a 10 por cento. As amostras dos alvéolos para processamento microbiológico foram coletadas dois dias após a realização das cirurgias e foram inoculadas em ágar sangue com ou sem 8 µg/mL de tetraciclina e em outros meios de cultura seletivos, incubadas em aerobiose ou anaerobiose, a 37ºC, de 2 a 14 dias. Verificou-se que a tetraciclina reduziu a ocorrência de alveolite e provocou uma modificação significativa na microbiota do sítio cirúrgico, levando a uma redução nas proporções ocupadas pelos microrganismos anaeróbios e uma elevação da participação de microrganismos resistentes à tetraciclina e outros antimicrobianos.

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

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.

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.

In vivo evaluation of the effect of essential oil-containing oral strips on salivary bacteria using the checkerboard method.

OBJECTIVE: The aim of this study was to evaluate the antimicrobial effect of essential oil-containing oral strips on different species of the oral microbiota. METHODOLOGY: Saliva samples were collected from 20 subjects with good oral health, diluted and plated onto blood agar medium. The subjects were asked to place the strip (Listerine PocketPaks) on the tongue allowing it to dissolve. After 30 minutes, new saliva samples were collected again and the plates with the samples were incubated under anaerobic conditions at 37 degrees C for seven days. Colony counts (CFU/mL) were determined for each sample. The colonies on the plates were washed with 1 mL of TE buffer, and the bacterial suspensions were processed for the identification of 24 species by DNA probes and the Checkerboard DNA-DNA hybridization method. Differences in total counts, prevalence, and levels of the species evaluated before and after placement of the strips were determined by Wilcoxon sign rank and Chi-square tests. RESULTS: A modest increase in the total bacterial number in saliva from 1.4 x 10(8) to 1.7 x 10(8) bacterial cells was observed 30 minutes after the strip placement, although this change was not significant (p = 0.632). Most of the species reduced in frequency and/or levels, including the pathogens A. actinomycetemcomitans, C. rectus, E. corrodens, Fusobacterium spp., P. intermedia, and S. noxia, as well as the beneficial species A. meyeri, A. georgia, A. gerencseriae, A. odontolyticus, and P. acnes after strip placement. In contrast, A. viscosus, P. melaninogenica, P. gingivalis, P. micros, Streptococcus spp., T. forsythensis, and V. parvula presented an increase in prevalence and/or levels. These changes were not statistically significant after adjusting for multiple comparisons (p > 0.0022). CONCLUSION: The use of the essential oil-containing oral strips resulted in a short-term small increase in the total number of salivary microorganisms. In addition, a not significant decrease of certain periodontopathogens, and an increase in species compatible with oral health were observed.

Comparative study between the effects of photodynamic therapy and conventional therapy on microbial reduction in ligature-induced peri-implantitis in dogs.

BACKGROUND: Progressive peri-implant bone losses, which are accompanied by inflammatory lesions in the soft tissues, are referred to as peri-implantitis. The aim of this study was to compare the effects of photodynamic therapy (PDT) and conventional technique on microbial reduction in ligature-induced peri-implantitis in dogs. METHODS: Eighteen third premolars from nine Labrador retriever dogs were extracted and the implants were submerged. After osseointegration, peri-implantitis was induced. After 4 months, ligature was removed and natural bacterial plaque was allowed to form for another 4 months. The animals were then randomly divided into two groups. In the conventional group, they were treated using mucoperiosteal flaps for scaling the implant surface and chlorexidine (conventional) irrigation. In the PDT group, only mucoperiosteal scaling was carried out before photodynamic therapy. Inside the peri-implant pocket, a paste-based azulene photosensitizer was placed and then a GaAlAs low-power laser (lambda=660 nm, P=40 mW, E=7.2 J for 3 minutes) was used. Microbiological samples were obtained before and immediately after treatment. Before treatment, one implant was removed and analyzed by scanning electron microscopy to validate the contamination. RESULTS: The results of this study showed that Prevotella sp., Fusobacterium sp., and S. Beta-haemolyticus were significantly reduced for both groups. After treatment, no significant differences were observed between the groups. CONCLUSION: These findings suggest that photodynamic therapy is a non-invasive method that could be used to reduce microorganisms in peri-implantitis.

Clindamycin-resistant Fusobacterium varium bacteremia and decubitus ulcer infection.

Bacteremia due to Fusobacterium spp. is unusual (<10% of cases of anaerobic bacteremia), and the isolation of Fusobacterium varium is especially uncommon. The most probable sources of Fusobacterium bacteremia are the respiratory, the gastrointestinal, and the genitourinary tracts. A.-M. Bourgault et al. (Clin. Infect. Dis. 25[Suppl. 2]:181-183) described 40 patients with Fusobacterium bacteremia; only 3 had Fusobacterium varium, and no one had decubitus scars as the portal of entry. In another published series (S. Henry, A. De Maria, and W. R. McCabe, Am. J. Med. 75:225-231, 1983) of 26 cases, two patients had concomitant pulmonary lesions and decubitus ulcers but there was no identification to the species level mentioned. We report a case of Fusobacterium varium bacteremia and infected sacral decubitus ulcer in an elderly patient.

Lethal photosensitization in microbiological treatment of ligature-induced peri-implantitis: a preliminary study in dogs.

This pilot study evaluated, by culture testing, the effectiveness of lethal photosensitization for the microbiological treatment of peri-implantitis in dogs. Experimental peri-implantitis was induced by ligature placement for 2 months. Following ligature removal, plaque control was instituted by scrubbing with 0.12% chlorhexidine daily for 12 months. Subsequently, mucoperiosteal flaps were elevated for scaling the implant surface. Microbial samples were obtained with paper points before and after treatment of implant surfaces by means of 100 microg/ml toluidine blue O (TBO,) and were exposed, for 80 s, to light with a wavelength of 685 nm from a 50 mW GaAlAs diode laser. The mean initial and final bacterial counts were 7.22 +/- 0.20 and 6.84 +/- 0.44 CFU/ml, respectively for TVC (P < 0.0001); 6.19 +/- 0.45 and 3.14 +/- 3.29 CFU/ml for P. intermedia/nigrescens (P = 0.001); 5.98 +/- 0.38 and 1.69 +/- 2.90 CFU/ml for Fusobacterium spp. (P = 0.001); and 6.07 +/- 0.22 to 1.69 +/- 2.94 CFU/ml for beta-hemolytic Streptococcus (P = 0.0039). It may be concluded that lethal photosensitization resulted in a reduction of the bacterial count. Complete elimination of bacteria was achieved in some samples.

Brazilian propolis: physicochemical properties, plant origin and antibacterial activity on periodontopathogens.

Propolis samples collected in the dry and rainy seasons, from an experimental apiary located in a cerrado vegetation region in Brazil were used in this study. Microscopic analysis showed the presence of 31 pollen types, secretory hairs (genus Baccharis) and fragments of plant epidermis. The oxidation rates and the wax content of the samples after physicochemical analyses were in agreement with the Cuban Guideline NRAG 870-88. A high performance liquid chromatography analysis showed a similar pattern of chromatograms, characterized by the presence of ten phenolic compounds. There was no significant difference in the pro fi le of phenolic compounds and also in the total flavonoid concentration in propolis samples collected in different seasons. Antibacterial assays were performed by the method of dilution of an ethanol extract of propolis (EEP) in agar (v/v%) and showed that all 16 A. actinomycetemcomitans strains tested were inhibited by propolis concentrations of 0.1% to 0.25%, and did not grow at all at 0.5%. The growth inhibition of six Fusobacterium spp. and 16 black-pigmented anaerobes was observed at concentrations of 0.05% to 0.1%, and no growth was observed at 0.25%. There was no effect of seasonality on the inhibitory activity of propolis. The antibiotics tetracycline and meropenem were used as positive controls.

Prueba de susceptibilidad antimicrobiana de un material de obturación endodóntica / Antimicrobial susceptibility test of an endodontic filling material

Los estudios y ensayos de laboratorio "in vitro" realizados en el presente trabajo con P.L.R.M. (pasta lentamente reabsorbible de Maisto) confirman un efecto bacteriostático con todas las cepas de microorganismos estudiados: Fusobacterium periodonticum ATCC 33693 Prevotella Melaninogénica ATCC 439822 Porphyromonas endodontalis ATCC 35406 Staphylococcus sp., Streptococcus viridans y Streptococcus Grupo A, en períodos de 0 a 56 días y valores de 1g. hasta 0,5mg/ml (AU)

Oral species of Fusobacterium from human and environmental samples.

PURPOSE: The aim of this study was the characterization and identification of oral Fusobacterium in patients with and without periodontal disease, and from spittoons and air-water syringes. The antimicrobial susceptibility of this bacterium was evaluated. METHOD: Subgingival samples were taken using sterilized absorbent paper points. Spittoon samples were collected using sterile swabs around the drain area with shut off, and air-water syringe samples by washing the tip with Ringer solution. Samples were transferred in tubes under CO2 flux. Diluted samples were inoculated on to Omata and Disraely agar and blood agar plates, which were incubated in anaerobiosis, at 37 degrees C, for 4 days. Bacterial species were identified biochemically. MIC was determined using an agar dilution method. RESULTS: Periodontal patients, healthy subjects, spittoons and air-water syringes were 80%, 67.6%, 37.8% and 3.3% positive to Fusobacterium, respectively. Clindamycin, imipenem, lincomycin, metronidazole and tetracycline were active against all human and environmental isolates. Eighteen isolates resistant to ampicillin or penicillin G produced beta-lactamases. The presence of human oral bacteria in items of dental equipment supports the hypothesis that such equipment may serve as a vehicle for the transmission of pathogenic organisms. CONCLUSION: Pieces of dental equipment may serve as a vehicle for the transmission of oral pathogenic organisms.

Sensibilidad in vitro de microorganismos anaeróbicos / In vitro sensibility of anaerobic microbial

Los estudios in vitro de sensibilidad antibiótica frente a bacterias anaeróbicas son escasos en nuestro medio. El presente trabajo evaluó la actividad antimicrobiana de seis antibióticos frente a 301 cepas de microorganismos anaeróbicos. Destaca la sensibilidad del grupo Bacteroides fragilis grupo, frente a la clindamicina, en especial cuando se compara con la actividad de metronidazol. Los Bacteroides melaninogenicus presentan una resistencia de 33% al metranidazol, condición que no está descrita en la literatura extranjera. La penicilina y el cloramfenicol son los más activos frente a los microorganismos Gram positivos anaeróbicos. La actividad de metronidazol frente a este grupo de microorganismos es la más baja de todos los antibióticos estudiados. La clindamicina, el cloramfenicol y los nitroimidazólicos presentan mejor actividad que la penicilina frente a los Clostrium perfringens