Susceptibility trends of Bacteroides fragilis group isolates from Buenos Aires, Argentina.

The aim of this study was to analyze the susceptibility trends to seven antibiotics of Bacteroides fragilis group isolates based on three survey studies performed by the Committee of Anaerobic Bacteria between 1989 and 2002. Fifty three, 82 and 65 B. fragilis group isolates were collected during each period. The antimicrobial agents included were: ampicillin, ampicillin-sulbactam (2:1), cefoxitin, piperacillin, imipenem, clindamycin, and metronidazole. Minimal inhibitory concentrations (MICs) were determined according to the reference agar dilution method described by the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS). The most active antibiotics for B. fragilis and non-B. fragilis species throughout the three periods were: imipenem with 99.1 and 100% of activity, respectively, and metronidazole with 100% of activity. The susceptibility to ampicillin-sulbactam showed a decrease, from 100% to 90.3% and to 82.4 % in the last period, for both B. fragilis and non-B. fragilis species, respectively. The overall susceptibility rates for cefoxitin, piperacillin, and clindamycin were significantly different between B. fragilis and non-B. fragilis species (84.2% vs. 56.5%; 85.9% vs. 66.7% and 88.8% vs. 64.7%, respectively, p < 0.05). Cefoxitin was the antibiotic that showed more variations as regards periods and species. The susceptibility rates for clindamycin were low, about 60%, for non-B. fragilis species during the last two periods. The variations observed in the susceptibility patterns of the B. fragilis group isolates emphasize the need to continue monitoring the emergence of resistance in order to guide the election of the most appropriate antibiotic therapy scheme for anaerobic infections.

["In vitro" activity of ten antimicrobial agents against anaerobic bacteria. A collaborative study, 1999-2002]. / Actividad "in vitro" de 10 antimicrobianos frente a bacterias anaerobias. Estudio multicéntrico, 1999-2002.

The antimicrobial activity of ampicillin, ampicillin-sulbactam, cefoxitin, ceftriaxone, imipenem, piperacillin, piperacillin-tazobactam, clindamycin, metronidazole, and azitromycin was assesed against 166 strains of anaerobic bacteria recovered from eight hospitals in Buenos Aires. The strains studied were Bacteroides fragilis group (65), Fusobacterium spp. (26), Prevotella spp. (21), Porphyromonas spp. (10), Clostridium difficile (10), other clostridia (12), and gram-positive cocci (22). The MICs were determined by the agar dilution method according to NCCLS document M11-A5. Metronidazole and piperacillin-tazobactam were the most active antimicrobial agents tested and exhibited MIC90 values of < or = 2 microg/ml and < or = 4 microg/ml against gram-negative organisms, and < or = 2 microg/ml, and < or = 8 microg/ml against gram-positive organisms, respectively. Among beta-lactams the activity against gram-negative rods was in the following order: imipenem > piperacillin > cefoxitin > ceftriaxone > ampicillin. Among the gram-positive bacteria the decreased activity was: piperacillin > imipenem > cefoxitin > ceftriaxone > ampicillin. The majority of the species studied showed different degrees of resistance to clindamycin and azitromycin. Nevertheless, 90% of Fusobacterium nucleatum and Porphyromonas spp. isolates were inhibited by 0.125 mg/ml of clindamycin and azitromycin, respectively.

Actividad “in vitro” de 10 antimicrobianos frente a bacterias anaerobias: Estudio multicéntrico, 1999-2002 / “In vitro” activity of ten antimicrobial agents against anaerobic bacteria. A collaborative study, 1999-2002

Se evaluó la actividad de ampicilina, ampicilina-sulbactama, cefoxitina, ceftriaxona, imipenem, piperacilina, piperacilina-tazobactama, clindamicina, metronidazol y azitromicina frente a 166 cepas de bacterias anaerobias aisladas en 8 hospitales de Buenos Aires. Se estudiaron: Bacteroides grupo fragilis (65), Fusobacterium spp. (26), Prevotella spp. (21), Porphyromonas spp. (10), Clostridium difficile (10), otros clostridios (12) y cocos gram-positivos (22). Las CIMs se determinaron usando el método patrón de dilución en agar recomendado por el NCCLS, documento M11-A5. Los antibióticos más activos fueron metronidazol y piperacilina-tazobactama que exhibieron valores de CIM90£ 2 µg/ml y £ 4 µg/ml frente a los microorganismos gram-negativos y £ 2 µg/ml y £ 8 µg/ml frente a los microorganismos gram-positivos, respectivamente. Entre los b-lactámicos el orden de actividad frente a bacilos gram-negativos fue: imipenem > piperacilina > cefoxitina > ceftriaxona > ampicilina. En gram-positivos la actividad decreciente fue: piperacilina> imipenem > cefoxitina > ceftriaxona > ampicilina. La mayoría de las especies estudiadas mostraron distintos niveles de resistencia con clindamicina y azitromicina. Sin embargo, el 90% de las cepas de Fusobacterium nucleatum y Por-phyromonas spp. fue inhibido por una concentración de 0,125 µg/ml de clindamicina y azitromicina, respectivamente.

The antimicrobial activity of ampicillin, ampicillin-sulbactam, cefoxitin, ceftriaxone, imipenem, piperacillin, piperacillin-tazobactam, clindamycin, metronidazole, and azitromycin was assesed against 166 strains of anaerobic bacteria recovered from eight hospitals in Buenos Aires. The strains studied were Bacteroidesfragilis group (65), Fusobacterium spp. (26), Prevotella spp. (21), Porphyromonas spp. (10), Clostridium difficile (10), other clostridia (12), and gram-positive cocci (22). The MICs were determined by the agar dilution method according to NCCLS document M11-A5. Metronidazole and piperacillin-tazobactam were the most active antimicrobial agents tested and exhibited MIC90values of £ 2 µg/ml and £ 4 µg/ml against gram-negative organisms, and £ 2 µg/ml, and £ 8 µg/ml against gram-positive organisms, respectively. Among b-lactams the activity against gram-negative rods was in the following order: imipenem> piperacillin > cefoxitin > ceftriaxone > ampicillin. Among the gram-positive bacteria the decreased activity was: piperacillin> imipenem> cefoxitin > ceftriaxone > ampicillin. The majority of the species studied showed different degrees of resistance to clindamycin and azitromycin. Nevertheless, 90% of Fusobacterium nucleatum and Porphyromonas spp. isolates were inhibited by 0.125 mg/ml of clindamycin and azitromycin, respectively.

Actividad [quot ]in vitro[quot ] de 10 antimicrobianos frente a bacterias anaerobias. Estudio multicéntrico, 1999-2002 / [[quot ]In vitro[quot ] activity of ten antimicrobial agents against anaerobic bacteria. A collaborative study, 1999-2002]

The antimicrobial activity of ampicillin, ampicillin-sulbactam, cefoxitin, ceftriaxone, imipenem, piperacillin, piperacillin-tazobactam, clindamycin, metronidazole, and azitromycin was assesed against 166 strains of anaerobic bacteria recovered from eight hospitals in Buenos Aires. The strains studied were Bacteroides fragilis group (65), Fusobacterium spp. (26), Prevotella spp. (21), Porphyromonas spp. (10), Clostridium difficile (10), other clostridia (12), and gram-positive cocci (22). The MICs were determined by the agar dilution method according to NCCLS document M11-A5. Metronidazole and piperacillin-tazobactam were the most active antimicrobial agents tested and exhibited MIC90 values of piperacillin > cefoxitin > ceftriaxone > ampicillin. Among the gram-positive bacteria the decreased activity was: piperacillin > imipenem > cefoxitin > ceftriaxone > ampicillin. The majority of the species studied showed different degrees of resistance to clindamycin and azitromycin. Nevertheless, 90

of Fusobacterium nucleatum and Porphyromonas spp. isolates were inhibited by 0.125 mg/ml of clindamycin and azitromycin, respectively.

Actividad [quot ]in vitro[quot ] de 10 antimicrobianos frente a bacterias anaerobias. Estudio multicéntrico, 1999-2002. / [[quot ]In vitro[quot ] activity of ten antimicrobial agents against anaerobic bacteria. A collaborative study, 1999-2002]

The antimicrobial activity of ampicillin, ampicillin-sulbactam, cefoxitin, ceftriaxone, imipenem, piperacillin, piperacillin-tazobactam, clindamycin, metronidazole, and azitromycin was assesed against 166 strains of anaerobic bacteria recovered from eight hospitals in Buenos Aires. The strains studied were Bacteroides fragilis group (65), Fusobacterium spp. (26), Prevotella spp. (21), Porphyromonas spp. (10), Clostridium difficile (10), other clostridia (12), and gram-positive cocci (22). The MICs were determined by the agar dilution method according to NCCLS document M11-A5. Metronidazole and piperacillin-tazobactam were the most active antimicrobial agents tested and exhibited MIC90 values of < or = 2 microg/ml and < or = 4 microg/ml against gram-negative organisms, and < or = 2 microg/ml, and < or = 8 microg/ml against gram-positive organisms, respectively. Among beta-lactams the activity against gram-negative rods was in the following order: imipenem > piperacillin > cefoxitin > ceftriaxone > ampicillin. Among the gram-positive bacteria the decreased activity was: piperacillin > imipenem > cefoxitin > ceftriaxone > ampicillin. The majority of the species studied showed different degrees of resistance to clindamycin and azitromycin. Nevertheless, 90

of Fusobacterium nucleatum and Porphyromonas spp. isolates were inhibited by 0.125 mg/ml of clindamycin and azitromycin, respectively.

A randomized and prospective study comparing treatment with high-dose intravenous immunoglobulin with monoclonal antibodies for rescue of kidney grafts with steroid-resistant rejection.

BACKGROUND: The aim of this study was to compare the effectiveness of intravenous immunoglobulin (IVIg) versus monoclonal anti-CD3 as a treatment for steroid-resistant rejections. From January 1995 to June 1997, 30 patients were analyzed. They were randomized into two groups. Resistant rejections were diagnosed by core biopsy. Group A received 500 mg/ kg/day IVIg (Sandoglobulin) for 7 consecutive days, whereas group B received 5 mg/day of OKT3 for 14 consecutive days. Daily T cell CD3+ peripheral count was performed for 14 days for group B. The immunosuppression was similar for both groups. Cyclosporine was stopped during both treatments. METHODS: Demographic factors, HLA mismatch, creatinine levels before and after treatment, and the incidence of rejections after treatment (up to 1 month) were taken into account for this study. RESULTS: Data from different samples were compared using Fisher's exact test. Graft and patient survival were analyzed using the Kaplan-Meier method. The were no significant differences found in age, graft origin, HLA mismatch, or time of follow-up until the episode of rejection. Success was achieved for 11 (73.3%) of 15 of group A and 13 (86.6%) of 15 of group B (P=0.79). Creatinine levels before and after treatment were as follows: A, 2.99+/-1.30 mg/dl and 2.1+/-0.70 mg/dl versus B, 3.1+/-1.1 mg/dl and 2.5+/-0.8 mg/dl. Besides, we did not observe differences in the creatinine 1 month after treatment (A: 2.35+/-0.78 mg/dl; B: 2.51+/-1.10 mg/dl; P=0.66) nor in the third month (A: 1.83+/-0.58 mg/dl; B: 2.30+/-0.89 mg/dl; P=0.24). The incidence of rejections after treatment was 5 (46%) of 11 for group A and 9 (75%) of 12 for group B (P=0.4). The patient survival rates 2 years after treatment were 87 and 92% for A and B groups, respectively. Graft survival was identical (80% in both groups). CONCLUSION: Should the favorable result presented in this report be confirmed in larger number of patients, IVIg could become the preferable choice of rejection treatment for steroid-resistant rejection because of a complete absence of the unwanted side effects commonly associated with OKT3.

Quantification of fecal neutrophils by MPO determination (myeloperoxidase) in patients with invasive diarrhea. Cuantificación de neutrofilos fecales mediante la determinación de MPO (Mieloperoxidasa) en pacientes con diarrea invasiva.

Myeloperoxidase (MPO), a specific polymorphonuclear leukocyte enzyme, has been used previously to quantify the number of neutrophils in tissue. MPO activity was found to be linearly related to the number of neutrophil cells. In an attempt to use this method in leukocytes measuring in stool, fecal MPO was solubilized with hexadecyltrimethylammonium bromide and the MPO activity was measured by a dianisidine-H2O2 assay. Stools from 10 normal subjects and 39 patients with diarrhea produced by enteropathogenic bacteria were examined for leukocytes by MPO activity as well as microscopically using methylene blue stain, MPO activity was positive in 36 patients (92%) and leukocytes were present by microscopic observation in 30 (77%). Fecal leukocytes were not found in healthy controls and the MPO activity was undectable. Stool MPO activity had a range of from 1.6 to 2,830.0 x 10(3) UMPO per gram of feces (median 460.0). The number of neutrophils obtained through MPO activity had a range of 6.0 to 13,216.0/ mm3 (median 1,261.0). Fecal MPO activity is a simple biochemical assay for the detection and quantification of fecal leukocytes.

Quantification of fecal neutrophils by MPO determination (myeloperoxidase) in patients with invasive diarrhea. Cuantificación de neutrofilos fecales mediante la determinación de MPO (Mieloperoxidasa) en pacientes con diarrea invasiva.

Myeloperoxidase (MPO), a specific polymorphonuclear leukocyte enzyme, has been used previously to quantify the number of neutrophils in tissue. MPO activity was found to be linearly related to the number of neutrophil cells. In an attempt to use this method in leukocytes measuring in stool, fecal MPO was solubilized with hexadecyltrimethylammonium bromide and the MPO activity was measured by a dianisidine-H2O2 assay. Stools from 10 normal subjects and 39 patients with diarrhea produced by enteropathogenic bacteria were examined for leukocytes by MPO activity as well as microscopically using methylene blue stain, MPO activity was positive in 36 patients (92

) and leukocytes were present by microscopic observation in 30 (77

). Fecal leukocytes were not found in healthy controls and the MPO activity was undectable. Stool MPO activity had a range of from 1.6 to 2,830.0 x 10(3) UMPO per gram of feces (median 460.0). The number of neutrophils obtained through MPO activity had a range of 6.0 to 13,216.0/ mm3 (median 1,261.0). Fecal MPO activity is a simple biochemical assay for the detection and quantification of fecal leukocytes.

Quantification of fecal neutrophils by MPO determination (myeloperoxidase) in patients with invasive diarrhea. Cuantificación de neutrofilos fecales mediante la determinación de MPO (Mieloperoxidasa) en pacientes con diarrea invasiva

Myeloperoxidase (MPO), a specific polymorphonuclear leukocyte enzyme, has been used previously to quantify the number of neutrophils in tissue. MPO activity was found to be linearly related to the number of neutrophil cells. In an attempt to use this method in leukocytes measuring in stool, fecal MPO was solubilized with hexadecyltrimethylammonium bromide and the MPO activity was measured by a dianisidine-H2O2 assay. Stools from 10 normal subjects and 39 patients with diarrhea produced by enteropathogenic bacteria were examined for leukocytes by MPO activity as well as microscopically using methylene blue stain, MPO activity was positive in 36 patients (92

) and leukocytes were present by microscopic observation in 30 (77

). Fecal leukocytes were not found in healthy controls and the MPO activity was undectable. Stool MPO activity had a range of from 1.6 to 2,830.0 x 10(3) UMPO per gram of feces (median 460.0). The number of neutrophils obtained through MPO activity had a range of 6.0 to 13,216.0/ mm3 (median 1,261.0). Fecal MPO activity is a simple biochemical assay for the detection and quantification of fecal leukocytes.

Broth disk elution method for anaerobic bacteria: a collaborative study to assess its reliability for clinical purposes.

A collaborative study involving seven laboratories was undertaken to evaluate the reproducibility and the reliability of the broth disk elution test against anaerobic bacteria by comparing with the reference agar dilution method. A two breakpoint broth test was also evaluated. Assays were performed using the same testing conditions (i.e. medium, temperature, atmosphere and incubation time). One hundred Gram-negative and Gram-positive clinical isolates were initially studied. Overall agreement of 98.5% and 97.5%, were found for disk elution and the two breakpoint tests, respectively. In order to assess the reliability of the disk elution test, two different lots (LOT1 and LOT2) of disks of piperacillin and clindamycin were selected, to obtain two final concentrations after dilution (10 and 60 mg/mL; 1 and 4 mg/mL, respectively). Two hundred and eighty assays were performed against one strain of both Bacteroides fragilis(piperacillin MIC, 8.0 mg/mL; clindamycin MIC, <0.5 mg/mL) and Bacteroides thetaiotaomicron(piperacillin MIC, 16.0 mg/mL; clindamycin MIC, <0.5 mg/mL). With LOT 1, considering both species and both antibiotics, the agreement among six laboratories ranged from 85% to 100% (P > 0.05) with the higher concentration. Overall agreement among all laboratories was 91%. No optimal agreement (>90%) for clindamycin-Bacteroides thetaiotaomicron using the LOT1 (77%) was found. Since this finding was not observed with LOT2 (100% agreement), discrepancies were attributed to variation between lots. Overall agreement with LOT2 was 100% for all centres. The present study indicates that the broth disk elution method proved to be a reliable and suitable alternative for routine susceptibility testing for anaerobic bacteria, as a resistance screening method for clinical purposes.

Abnormal fecal flora in a patient with short bowel syndrome. An in vitro study on effect of pH on D-lactic acid production.

D-Lactic acidosis associated with encephalopathy is a clinical condition that occurs in patients with short bowel syndrome. We studied the fecal flora and the composition of fecal water of a child who developed this unusual disorder. Bacteriological studies showed that the patient's stool contained a marked predominance of gram-positive anaerobes. Two strains were identified, Lactobacillus plantarum and Lactobacillus salivarius, as the main bacteria isolated. Fecal water showed pH 4.8 and total lactic acid (sum of L- and D-lactic acids) was the principal organic anion found in the feces. We also incubated the patient's stool in a continuous culture with a view to determining the effect of the pH on the production of volatile fatty acids (VFA) and L- and D-lactic acids. The culture was maintained at pH 5.0, 5.5, 6.0, and 6.5 for four consecutive periods of four days each. We then studied the culture for a further four days at pH 5.0 once again. This study showed that with the progressive rise of the pH from 5.0 to 6.5 L- and D-lactic acids decreased and VFA production increased. D-Lactic acid formation was inhibited at pH 6.5, but when the culture was returned to pH 5.0, it increased to a high level again. These results suggest that the pH plays an important role in the ecological changes in the colonic bacteria that result in D-lactic acid production.

Estudio multicéntrico de la sensibilidad de bacterias anaerobias en la Argentina / Multicentric study of anaerobic bacteria susceptibility in Argentina

Se determinó la actividad de ampicilina (AMP), ampicilina-sulbactama (AMS), penicilina (PEN), piperacilina (PIP), imipenem (IMI), cefoxitina (CXT), ceftizoxima (CFZ), clindamicina (CLI), cloranfenicol (CLO) y metronidazol (MET) frente a 106 cepas de bacterias anaerobias aisladas de muestras clínicas en seis centros asistenciales del país por un método de dilución en agar. Todos los microorganismos gramnegativos fueron sensibles a AMS, CLO, IMI y MET. Se encontraron 5/7 Bacteroides spp., 2/6 bacilos gram negativos pigmentados y 1/4 Fusobacterium spp. resistentes a AMP. Los Bacteroides del grupo fragilis fueron altamente resistentes a AMP y la especie Bacteroides fragilis fue más sensible a PIP, CXT, CFZ y CLI que las otras especies del grupo (5 por ciento vs. 21 por ciento, 5 por ciento vs. 7 por ciento, 8 por ciento vs. 14 por ciento y 2,5 por ciento vs. 14 por ciento respectivamente). Entre los organismos gram positivos se encontró resistencia PEN en el 7 por ciento de Peptostreptococcus spp., a MET en 4 de 5 bacilos no esporulados y sensibilidad al resto de los antibióticos (AU)

Estudio multicéntrico de la sensibilidad de bacterias anaerobias en la Argentina / Multicentric study of anaerobic bacteria susceptibility in Argentina

Se determinó la actividad de ampicilina (AMP), ampicilina-sulbactama (AMS), penicilina (PEN), piperacilina (PIP), imipenem (IMI), cefoxitina (CXT), ceftizoxima (CFZ), clindamicina (CLI), cloranfenicol (CLO) y metronidazol (MET) frente a 106 cepas de bacterias anaerobias aisladas de muestras clínicas en seis centros asistenciales del país por un método de dilución en agar. Todos los microorganismos gramnegativos fueron sensibles a AMS, CLO, IMI y MET. Se encontraron 5/7 Bacteroides spp., 2/6 bacilos gram negativos pigmentados y 1/4 Fusobacterium spp. resistentes a AMP. Los Bacteroides del grupo fragilis fueron altamente resistentes a AMP y la especie Bacteroides fragilis fue más sensible a PIP, CXT, CFZ y CLI que las otras especies del grupo (5 por ciento vs. 21 por ciento, 5 por ciento vs. 7 por ciento, 8 por ciento vs. 14 por ciento y 2,5 por ciento vs. 14 por ciento respectivamente). Entre los organismos gram positivos se encontró resistencia PEN en el 7 por ciento de Peptostreptococcus spp., a MET en 4 de 5 bacilos no esporulados y sensibilidad al resto de los antibióticos