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Papers by Leslie Claude Benchetrit

Journal of Clinical Microbiology, 1992

A suitable test was developed for distinguishing group B streptococci from other beta-hemolytic s... more A suitable test was developed for distinguishing group B streptococci from other beta-hemolytic streptococci during growth in liquid medium. One hundred and sixty of 161 human group B strains tested yielded positive reactions within a 5 h incubation. The dye medium tested is a reliable substitute for more expensive serological procedures.

Zentralblatt für Bakteriologie, Mikrobiologie und Hygiene. 1. Abt. Originale. A, Medizinische Mikrobiologie, Infektionskrankheiten und Parasitologie, 1984

Production of hyaluronidase by 147 strains of beta hemolytic streptococci was studied employing a... more Production of hyaluronidase by 147 strains of beta hemolytic streptococci was studied employing a sensitive dye-binding assay and levels of enzyme activity were evaluated statistically. The analysis of variance showed that group A strains isolated in Rio de Janeiro produced significantly smaller amounts of enzyme than group A strains from a Minneapolis (USA) collection or than groups Band G brazilian isolates. The t test revealed that M not typable noselthroat group A strains produced more hyaluronidase than skin isolates. The analysis of variance did not show a significant difference in the enzyme production between M typable and not typable brazilian strains of group A streptococci. High enzyme-producing strains were not restricted to a few serotypes of group B streptococci. Zusammenfassung Die Hyaluronidasebildung von 147 Stammen ~-hamolysierender Streptokokken wurde mit einem empfindlichen Farbstoffbindungstest untersucht und die gebildeten Enzymmengen statistisch ausgewertet. Die Varianzanalyse ergab, daB Streptococcus pyogenes (Gruppe A)-Stamme, die in Rio de Janeiro isoliert wurden, geringere Enzymmengen produzierten als A-Streptokokkenstamme aus MinneapolislUSA, sowie B-bzw. G-Streptokokkenstamme brasilianischer Herkunft. Mit dem t-Test konnte nachgewiesen werden, daB die mit den verfiigbaren Anti-M-Antiseren nicht zu typisierenden S. pyogenes-Stamme aus dem Nasen-* Dedicated to the memory of Dr. Lewis W. Wannamaker. L. C. Benchetrit et al. Rachenraum mehr Hyaluronidase bildeten als Isolate von der Haut. Zwischen M-typisierbaren und nicht-typisierbaren (M+ bzw. M-) A-Streptokokken aus Brasilien lieR sich mit Hilfe der Varianzanalyse kein signifikanter Unterschied in der Enzymproduktion nachweisen. Stamme mit starker Hyaluronidasebildung fanden sich bei allen serologischen Typen von B-Streptokokken.

Rev Microbiol, Dec 1, 1995

Revista do Instituto de Medicina Tropical de São Paulo, 2008

The minimum inhibitory concentration and post-antibiotic effects of an antimicrobial agent are pa... more The minimum inhibitory concentration and post-antibiotic effects of an antimicrobial agent are parameters to be taken into consideration when determining its dosage schedules. The in vitro post-antibiotic effects on cell surface hydrophobicity and bacterial adherence were examined in one strain of group B streptococci. Exposure of the microorganism for 2 h at 37 °C to 1 x MIC of penicillin induced a PAE of 1.1 h. The cell surface charge of the Streptococcus was altered significantly during the post-antibiotic phase as shown by its ability to bind to xylene: hydrophobicity was decreased. Bacterial adherence to human buccal epithelial cells was also reduced. The results of the present investigation indicate that studies designed to determine therapeutic regimens should evaluate the clinical significance of aspects of bacterial physiology during the post-antibiotic period.

Revista do Instituto de Medicina Tropical de São Paulo, 1986

O efeito de concentrações subinibitórias de penicilina sobre a produção do antígeno grupo-específ... more O efeito de concentrações subinibitórias de penicilina sobre a produção do antígeno grupo-específico e da hialuronidase extracelular foi avaliado em uma amostra de estreptococo pertencente ao grupo G de Lancefield. Em todas as concentrações uma maior quantidade de antígeno grupo-específico foi extraída das células e a atividade específica de hialuronidase se mostrou aumentada em até 1400% nos sobrenadantes das culturas. O maior aumento na expressão de ambos os antígenos foi observado em 1/2 da CMI.

Zentralblatt für Bakteriologie, 1990

The effect of a subminimal inhibitory concentration of penicillin on the production of bound and ... more The effect of a subminimal inhibitory concentration of penicillin on the production of bound and free hemolysins by streptococci was examined using sheep red blood cells. A marked decrease of a group C cell-free and bound activities was observed with penicillin at a concentration of 1/3 of the MIC whereas an increase was observed with those of a group G strain. Potassium ferricyanide and anti-streptolysin 0 (group A streptococcus) were strongly inhibitory for the free activities of both strains. The cell-bound activities were stimulated by addition of RNA during bacterial growth in control cultures and also in drug-containing media. Zusammenfassung Es wurde der EinfluS subinhibitorischer Penicillin-Konzentrationen auf die Bildung freier und gebundener Hamolysine durch Streptokokken unter Verwendung von Schaf-Erythrozyten untersucht. Ein deutlicher Abfall zellfreier und gebundener Aktivitaten wurde in Gegenwart von 113 der MIK des Penicillins bei Gruppe C-Streptokokken beobachtet, wahrend bei Gruppe G-Streptokokken ein Anstieg auftrat. Kaliumferricyanid und Antistreptolysin 0 (Gruppe A-Streptokokken) hemmten die freien Aktivitaen beider Stamme. Die zellgebundenen Aktivitaten wurden durch RNA-Zusatz wahrend des bakteriellen Wachstums in Kontrollmedien und in Gegenwart verschiedener Zusatze stimuliert.

Zentralblatt für Bakteriologie, 1992

Pro duction of extracellular deoxyribonuclease by 394 strains of beta hemolytic streptoco cci was... more Pro duction of extracellular deoxyribonuclease by 394 strains of beta hemolytic streptoco cci was examined emp loying a deoxy ribonucleic acid-methyl green assay. Enzyma tic activi ties were measured in supern atants of bacterial cultures. Of the stra ins tested, 316 (80%) produced the enzyme. Nuclease production was demonstrated in 100% of gro up A strains and in 85, 74 and 58% of groups B, C an d G, respectively. Levels of nuclease activity were then evalua ted sta tistically. T he analysis of varia nce showed that group A strains produced more enzyme th an did streptococci of grou ps B, Cor G. Group B strai ns produced less nuclease tha n did isolates of groups C or G. There was no significant differe nce in the levels of nuclease produced by groups C and G or by th e var ious serological types of gro up B streptococci. Human gro up C strains produced mor e enzyme than ani mal strai ns. Zusammenfassung M it H ilfe des Desoxyribonukleinsau re-M eth ylgriin-Te sts wurde die Desoxyribonukleasebildung von 394 Stammen~-hamolysierender Strepto kok ken unrersuchr, Die enzymatische Aktivitar wurde in den Kulruruberstanden bestim mt. Von den 394 unters uchten Stam men bildeten 316 (80%) DNasen. DNase-Aktivita t war bei samtlichen Stammen der Gr uppe A nachweisbar sowie bei 85, 74 bzw. 58% der Sramrne der Gru ppen B, C bzw. G. Im Ergebnis derVar ianzan alyse zeigte sieh, daG S. pyogenes-Stamme mehr DNase bilden als Starnrne der Gruppen B, Coder G. Irn • Corresponding a uthor B.T. Ferreira et al. Vergleich zu Stammen der Gruppen C und G bildeten die B-Stamme geringere Mengen des Enzyms. lnnerhalb der Gruppen C und G sowie der serologischen Typen der Gruppe B waren keine statistisch signifikanten Unterschiede in der DNase-Bildung nachweisbar. Vom Menschen isolierte Starnrne der Gruppe C bildeten mehr DNase als vom Tier isolierte Sramrne.

Brazilian Journal of Microbiology, 2014

Streptococcus agalactiae (GBS) is a major source of human perinatal diseases and bovine mastitis.... more Streptococcus agalactiae (GBS) is a major source of human perinatal diseases and bovine mastitis. Erythromycin (Ery) and tetracycline (Tet) are usually employed for preventing human and bovine infections although resistance to such agents has become common among GBS strains. Ery and Tet resistance genes are usually carried by conjugative transposons (CTns) belonging to the Tn916 family, but their presence and transferability among GBS strains have not been totally explored. Here we evaluated the presence of Tet resistance genes (tetM and tetO) and CTns among Ery-resistant (Ery-R) and Ery-susceptible (Ery-S) GBS strains isolated from human and bovine sources; and analyzed the ability for transferring resistance determinants between strains from both origins. Tet resistance and int-Tn genes were more common among Ery-R when compared to Ery-S isolates. Conjugative transfer of all resistance genes detected among the GBS strains included in this study (ermA, ermB, mef, tetM and tetO), in frequencies between 1.10-7 and 9.10-7 , was possible from bovine donor strains to human recipient strain, but not the other way around. This is, to our knowledge, the first report of in vitro conjugation of Ery and Tet resistance genes among GBS strains recovered from different hosts.

The Brazilian Journal of Infectious Diseases, 2013

Streptococcus agalactiae is a common agent of clinical and subclinical bovine mastitis and an imp... more Streptococcus agalactiae is a common agent of clinical and subclinical bovine mastitis and an important cause of human infections, mainly among pregnant women, neonates and nonpregnant adults with underlying diseases. The present study describes the genetic and phenotypic diversity among 392 S. agalactiae human and bovine strains isolated between 1980 and 2006 in Brazil. The most prevalent serotypes were Ia, II, III and V and all the strains were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampicin and tetracycline was observed. Among the erythromycin resistant strains, mefA/E, ermA and, mainly, ermB gene were detected, and a shift of prevalence from the macrolide resistance phenotype to the macrolidelincosamide-streptogramin B resistance phenotype over the years was observed. The 23 macrolide-resistant strains showed 19 different pulsed-field gel electrophoresis profiles. Regarding macrolide resistance, a major concern in S. agalactiae epidemiology, the present study describes an increase in erythromycin resistance from the 80s to the 90s followed by a decrease in the 2000-2006 period. Also, the genetic heterogeneity described points out that erythromycin resistance in Brazil is rather due to horizontal gene transmission than to spreading of specific macrolide-resistant clones.

Zentralblatt für Bakteriologie, 1989

The effects of subMICs of penicillin and clindamycin on group A streptococcal products were analy... more The effects of subMICs of penicillin and clindamycin on group A streptococcal products were analyzed. Penicillin caused an increase in the expression of the group carbohydrate for the three strains tested; in contrast, clindamycin inhibited the expression in two strains. The M and T proteins were not affected by the drugs. Clindamycin caused an increase in the hyaluronidase activity and both antimicrobial agents inhibited the activity of streptolysin at 1/2 MIC.

Virology, 1974

Abstract Internal protein precursors (IP) are formed in Escherichia coli B cells, soon after infe... more Abstract Internal protein precursors (IP) are formed in Escherichia coli B cells, soon after infection with bacteriophage T4. These precursors are cleaved to internal protein products (IP∗) in E. coli B infected with a wild type of T4, but not after infection with an amber mutant defective in gene 21. It has been shown that T4 internal protein products (IP∗), formed either in vitro or in vivo , interact with T4 DNA, but not with the DNA of E. coli B, Clostridium perfringens , bacteriophage T2, lambda, or ∅X174. The specific binding of T4 internal proteins to T4 DNA is not due to glucose residues on phage DNA, since DNA preparations from a glucosyl transferase mutant (T4 am αgt am βgt ) or T4 DNA after digestion with β-glucosidase, retain their ability to bind T4 internal proteins. Internal protein precursors (IP) do not form detectable complexes with phage DNA. The proteins bound to T4 DNA in vitro , have been identified as internal proteins by polyacrylamide gel electrophoresis and have the respective molecular weights of 7600, 8600 and 18,000 d.

Virology, 1976

ABSTRACT A proteolytic enzyme has been extracted from Escherichia coli B cells infected with bact... more ABSTRACT A proteolytic enzyme has been extracted from Escherichia coli B cells infected with bacteriophage T4. The enzyme has been isolated in a highly purified form. The protein has a molecular weight of 31,000, an isoelectric point of about 9, and a sedimentation constant of 3.12 s.

Memórias do Instituto Oswaldo Cruz, 2009

Group B streptococci (GBS) infections occur worldwide. Although serotyping has been used for epid... more Group B streptococci (GBS) infections occur worldwide. Although serotyping has been used for epidemiologic purposes, this does not accurately characterize enough members of a genetically heterogeneous bacterial population. The aims of this work were to evaluate the genetic diversity of 45 type Ia GBS strains isolated in Brazil by pulsed-field gel electrophoresis as well as to evaluate antimicrobial susceptibility profiles and identify virulence genes. Twenty-four strains were assigned to cluster A. All strains under study contained the hylB and scpB genes. The bca gene was detected in only 10 strains and none of the streptococci carried the bac gene. Thirty-nine strains were resistant to tetracycline.

Memórias do Instituto Oswaldo Cruz, 1995

Memórias do Instituto Oswaldo Cruz, 2011

Streptococcus agalactiae isolates are more common among pregnant women, neonates and nonpregnant ... more Streptococcus agalactiae isolates are more common among pregnant women, neonates and nonpregnant adults with underlying diseases compared to other demographic groups. In this study, we evaluate the genetic and phenotypic diversity in S. agalactiae strains from Rio de Janeiro (RJ) that were isolated from asymptomatic carriers. We analysed these S. agalactiae strains using pulsed-field gel electrophoresis (PFGE), serotyping and antimicrobial susceptibility testing, as well as by determining the macrolide resistance phenotype, and detecting the presence of the ermA/B, mefA/E and lnuB genes. The serotypes Ia, II, III and V were the most prevalent serotypes observed. The 60 strains analysed were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampin and tetracycline was observed. Among the erythromycin and/or clindamycin resistant strains, the ermA, ermB and mefA/E genes were detected and the constitutive macrolides, lincosamides and streptogramin B-type resistance was the most prevalent phenotype observed. The lnuB gene was not detected in any of the strains studied. We found 56 PFGE electrophoretic profiles and only 22 of them were allocated in polymorphism patterns. This work presents data on the genetic diversity and prevalent capsular serotypes among RJ isolates. Approximately 85% of these strains came from pregnant women; therefore, these data may be helpful in developing future prophylaxis and treatment strategies for neonatal syndromes in RJ.

Journal of General Virology, 1976

Internal proteins, synthesized in T2-infected Eseherichia coli 8 cells were recovered from bacter... more Internal proteins, synthesized in T2-infected Eseherichia coli 8 cells were recovered from bacterial membranes during the early stages of infection. Approx. i5 rain after the onset of infection, T2 and T4 internal proteins were released from the bacterial membranes and sedimented along with newly synthesized phage DNA. Internal protein-DNA complexes were also obtained by chromatography on hydroxylapatite columns. Internal proteins were not released from bacterial membranes after infection with amber mutants defective in genes 2 I, 22 and 23. It has been suggested that these complexes are intermediates in T-even phage morphogenesis.

Journal of General Virology, 1976

Polypeptides of low tool. wt. have been extracted from T4 coliphages and from Escherichia coli B ... more Polypeptides of low tool. wt. have been extracted from T4 coliphages and from Escherichia coli B cells infected with a wild type and various amber mutants of bacteriophage T4. Six peptides were fractionated by chromatography on phosphocellulose: three of them were cleaved from proteins synthesized late in infection and related to phage head. The remaining three peptides have been shown to arise from early-labelled phage-induced proteins. Two of these six small petide fragments were found in the head of the T4 phage.

Journal of Ethnopharmacology, 1995

A fraction obtained from the culture fluids ofPycnoporus sanguineus fungus was shown to contain a... more A fraction obtained from the culture fluids ofPycnoporus sanguineus fungus was shown to contain a compound with biological activity against strains of Escherichia coil, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and members of the genus Streptococcus. The fraction was clearly more active on Gram-positive cocci than on Gram-negative bacilli.

Journal of Antimicrobial Chemotherapy, 1995

Upon the addition of beta-lactam antibiotics at concentrations that caused a 50% reduction in the... more Upon the addition of beta-lactam antibiotics at concentrations that caused a 50% reduction in the dry weight, beta-haemolytic streptococci produced increased amount of rhamnose, though the hexosamine content remained unchanged. These sugars are components of C-carbohydrate. Sialic acid content also increased in group B streptococcal surfaces and penicillin treatment generated new accessible surface sialic acid residues.

Journal of Clinical Microbiology, 1992

A suitable test was developed for distinguishing group B streptococci from other beta-hemolytic s... more A suitable test was developed for distinguishing group B streptococci from other beta-hemolytic streptococci during growth in liquid medium. One hundred and sixty of 161 human group B strains tested yielded positive reactions within a 5 h incubation. The dye medium tested is a reliable substitute for more expensive serological procedures.

Zentralblatt für Bakteriologie, Mikrobiologie und Hygiene. 1. Abt. Originale. A, Medizinische Mikrobiologie, Infektionskrankheiten und Parasitologie, 1984

Production of hyaluronidase by 147 strains of beta hemolytic streptococci was studied employing a... more Production of hyaluronidase by 147 strains of beta hemolytic streptococci was studied employing a sensitive dye-binding assay and levels of enzyme activity were evaluated statistically. The analysis of variance showed that group A strains isolated in Rio de Janeiro produced significantly smaller amounts of enzyme than group A strains from a Minneapolis (USA) collection or than groups Band G brazilian isolates. The t test revealed that M not typable noselthroat group A strains produced more hyaluronidase than skin isolates. The analysis of variance did not show a significant difference in the enzyme production between M typable and not typable brazilian strains of group A streptococci. High enzyme-producing strains were not restricted to a few serotypes of group B streptococci. Zusammenfassung Die Hyaluronidasebildung von 147 Stammen ~-hamolysierender Streptokokken wurde mit einem empfindlichen Farbstoffbindungstest untersucht und die gebildeten Enzymmengen statistisch ausgewertet. Die Varianzanalyse ergab, daB Streptococcus pyogenes (Gruppe A)-Stamme, die in Rio de Janeiro isoliert wurden, geringere Enzymmengen produzierten als A-Streptokokkenstamme aus MinneapolislUSA, sowie B-bzw. G-Streptokokkenstamme brasilianischer Herkunft. Mit dem t-Test konnte nachgewiesen werden, daB die mit den verfiigbaren Anti-M-Antiseren nicht zu typisierenden S. pyogenes-Stamme aus dem Nasen-* Dedicated to the memory of Dr. Lewis W. Wannamaker. L. C. Benchetrit et al. Rachenraum mehr Hyaluronidase bildeten als Isolate von der Haut. Zwischen M-typisierbaren und nicht-typisierbaren (M+ bzw. M-) A-Streptokokken aus Brasilien lieR sich mit Hilfe der Varianzanalyse kein signifikanter Unterschied in der Enzymproduktion nachweisen. Stamme mit starker Hyaluronidasebildung fanden sich bei allen serologischen Typen von B-Streptokokken.

Rev Microbiol, Dec 1, 1995

Revista do Instituto de Medicina Tropical de São Paulo, 2008

The minimum inhibitory concentration and post-antibiotic effects of an antimicrobial agent are pa... more The minimum inhibitory concentration and post-antibiotic effects of an antimicrobial agent are parameters to be taken into consideration when determining its dosage schedules. The in vitro post-antibiotic effects on cell surface hydrophobicity and bacterial adherence were examined in one strain of group B streptococci. Exposure of the microorganism for 2 h at 37 °C to 1 x MIC of penicillin induced a PAE of 1.1 h. The cell surface charge of the Streptococcus was altered significantly during the post-antibiotic phase as shown by its ability to bind to xylene: hydrophobicity was decreased. Bacterial adherence to human buccal epithelial cells was also reduced. The results of the present investigation indicate that studies designed to determine therapeutic regimens should evaluate the clinical significance of aspects of bacterial physiology during the post-antibiotic period.

Revista do Instituto de Medicina Tropical de São Paulo, 1986

O efeito de concentrações subinibitórias de penicilina sobre a produção do antígeno grupo-específ... more O efeito de concentrações subinibitórias de penicilina sobre a produção do antígeno grupo-específico e da hialuronidase extracelular foi avaliado em uma amostra de estreptococo pertencente ao grupo G de Lancefield. Em todas as concentrações uma maior quantidade de antígeno grupo-específico foi extraída das células e a atividade específica de hialuronidase se mostrou aumentada em até 1400% nos sobrenadantes das culturas. O maior aumento na expressão de ambos os antígenos foi observado em 1/2 da CMI.

Zentralblatt für Bakteriologie, 1990

The effect of a subminimal inhibitory concentration of penicillin on the production of bound and ... more The effect of a subminimal inhibitory concentration of penicillin on the production of bound and free hemolysins by streptococci was examined using sheep red blood cells. A marked decrease of a group C cell-free and bound activities was observed with penicillin at a concentration of 1/3 of the MIC whereas an increase was observed with those of a group G strain. Potassium ferricyanide and anti-streptolysin 0 (group A streptococcus) were strongly inhibitory for the free activities of both strains. The cell-bound activities were stimulated by addition of RNA during bacterial growth in control cultures and also in drug-containing media. Zusammenfassung Es wurde der EinfluS subinhibitorischer Penicillin-Konzentrationen auf die Bildung freier und gebundener Hamolysine durch Streptokokken unter Verwendung von Schaf-Erythrozyten untersucht. Ein deutlicher Abfall zellfreier und gebundener Aktivitaten wurde in Gegenwart von 113 der MIK des Penicillins bei Gruppe C-Streptokokken beobachtet, wahrend bei Gruppe G-Streptokokken ein Anstieg auftrat. Kaliumferricyanid und Antistreptolysin 0 (Gruppe A-Streptokokken) hemmten die freien Aktivitaen beider Stamme. Die zellgebundenen Aktivitaten wurden durch RNA-Zusatz wahrend des bakteriellen Wachstums in Kontrollmedien und in Gegenwart verschiedener Zusatze stimuliert.

Zentralblatt für Bakteriologie, 1992

Pro duction of extracellular deoxyribonuclease by 394 strains of beta hemolytic streptoco cci was... more Pro duction of extracellular deoxyribonuclease by 394 strains of beta hemolytic streptoco cci was examined emp loying a deoxy ribonucleic acid-methyl green assay. Enzyma tic activi ties were measured in supern atants of bacterial cultures. Of the stra ins tested, 316 (80%) produced the enzyme. Nuclease production was demonstrated in 100% of gro up A strains and in 85, 74 and 58% of groups B, C an d G, respectively. Levels of nuclease activity were then evalua ted sta tistically. T he analysis of varia nce showed that group A strains produced more enzyme th an did streptococci of grou ps B, Cor G. Group B strai ns produced less nuclease tha n did isolates of groups C or G. There was no significant differe nce in the levels of nuclease produced by groups C and G or by th e var ious serological types of gro up B streptococci. Human gro up C strains produced mor e enzyme than ani mal strai ns. Zusammenfassung M it H ilfe des Desoxyribonukleinsau re-M eth ylgriin-Te sts wurde die Desoxyribonukleasebildung von 394 Stammen~-hamolysierender Strepto kok ken unrersuchr, Die enzymatische Aktivitar wurde in den Kulruruberstanden bestim mt. Von den 394 unters uchten Stam men bildeten 316 (80%) DNasen. DNase-Aktivita t war bei samtlichen Stammen der Gr uppe A nachweisbar sowie bei 85, 74 bzw. 58% der Sramrne der Gru ppen B, C bzw. G. Im Ergebnis derVar ianzan alyse zeigte sieh, daG S. pyogenes-Stamme mehr DNase bilden als Starnrne der Gruppen B, Coder G. Irn • Corresponding a uthor B.T. Ferreira et al. Vergleich zu Stammen der Gruppen C und G bildeten die B-Stamme geringere Mengen des Enzyms. lnnerhalb der Gruppen C und G sowie der serologischen Typen der Gruppe B waren keine statistisch signifikanten Unterschiede in der DNase-Bildung nachweisbar. Vom Menschen isolierte Starnrne der Gruppe C bildeten mehr DNase als vom Tier isolierte Sramrne.

Brazilian Journal of Microbiology, 2014

Streptococcus agalactiae (GBS) is a major source of human perinatal diseases and bovine mastitis.... more Streptococcus agalactiae (GBS) is a major source of human perinatal diseases and bovine mastitis. Erythromycin (Ery) and tetracycline (Tet) are usually employed for preventing human and bovine infections although resistance to such agents has become common among GBS strains. Ery and Tet resistance genes are usually carried by conjugative transposons (CTns) belonging to the Tn916 family, but their presence and transferability among GBS strains have not been totally explored. Here we evaluated the presence of Tet resistance genes (tetM and tetO) and CTns among Ery-resistant (Ery-R) and Ery-susceptible (Ery-S) GBS strains isolated from human and bovine sources; and analyzed the ability for transferring resistance determinants between strains from both origins. Tet resistance and int-Tn genes were more common among Ery-R when compared to Ery-S isolates. Conjugative transfer of all resistance genes detected among the GBS strains included in this study (ermA, ermB, mef, tetM and tetO), in frequencies between 1.10-7 and 9.10-7 , was possible from bovine donor strains to human recipient strain, but not the other way around. This is, to our knowledge, the first report of in vitro conjugation of Ery and Tet resistance genes among GBS strains recovered from different hosts.

The Brazilian Journal of Infectious Diseases, 2013

Streptococcus agalactiae is a common agent of clinical and subclinical bovine mastitis and an imp... more Streptococcus agalactiae is a common agent of clinical and subclinical bovine mastitis and an important cause of human infections, mainly among pregnant women, neonates and nonpregnant adults with underlying diseases. The present study describes the genetic and phenotypic diversity among 392 S. agalactiae human and bovine strains isolated between 1980 and 2006 in Brazil. The most prevalent serotypes were Ia, II, III and V and all the strains were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampicin and tetracycline was observed. Among the erythromycin resistant strains, mefA/E, ermA and, mainly, ermB gene were detected, and a shift of prevalence from the macrolide resistance phenotype to the macrolidelincosamide-streptogramin B resistance phenotype over the years was observed. The 23 macrolide-resistant strains showed 19 different pulsed-field gel electrophoresis profiles. Regarding macrolide resistance, a major concern in S. agalactiae epidemiology, the present study describes an increase in erythromycin resistance from the 80s to the 90s followed by a decrease in the 2000-2006 period. Also, the genetic heterogeneity described points out that erythromycin resistance in Brazil is rather due to horizontal gene transmission than to spreading of specific macrolide-resistant clones.

Zentralblatt für Bakteriologie, 1989

The effects of subMICs of penicillin and clindamycin on group A streptococcal products were analy... more The effects of subMICs of penicillin and clindamycin on group A streptococcal products were analyzed. Penicillin caused an increase in the expression of the group carbohydrate for the three strains tested; in contrast, clindamycin inhibited the expression in two strains. The M and T proteins were not affected by the drugs. Clindamycin caused an increase in the hyaluronidase activity and both antimicrobial agents inhibited the activity of streptolysin at 1/2 MIC.

Virology, 1974

Abstract Internal protein precursors (IP) are formed in Escherichia coli B cells, soon after infe... more Abstract Internal protein precursors (IP) are formed in Escherichia coli B cells, soon after infection with bacteriophage T4. These precursors are cleaved to internal protein products (IP∗) in E. coli B infected with a wild type of T4, but not after infection with an amber mutant defective in gene 21. It has been shown that T4 internal protein products (IP∗), formed either in vitro or in vivo , interact with T4 DNA, but not with the DNA of E. coli B, Clostridium perfringens , bacteriophage T2, lambda, or ∅X174. The specific binding of T4 internal proteins to T4 DNA is not due to glucose residues on phage DNA, since DNA preparations from a glucosyl transferase mutant (T4 am αgt am βgt ) or T4 DNA after digestion with β-glucosidase, retain their ability to bind T4 internal proteins. Internal protein precursors (IP) do not form detectable complexes with phage DNA. The proteins bound to T4 DNA in vitro , have been identified as internal proteins by polyacrylamide gel electrophoresis and have the respective molecular weights of 7600, 8600 and 18,000 d.

Virology, 1976

ABSTRACT A proteolytic enzyme has been extracted from Escherichia coli B cells infected with bact... more ABSTRACT A proteolytic enzyme has been extracted from Escherichia coli B cells infected with bacteriophage T4. The enzyme has been isolated in a highly purified form. The protein has a molecular weight of 31,000, an isoelectric point of about 9, and a sedimentation constant of 3.12 s.

Memórias do Instituto Oswaldo Cruz, 2009

Group B streptococci (GBS) infections occur worldwide. Although serotyping has been used for epid... more Group B streptococci (GBS) infections occur worldwide. Although serotyping has been used for epidemiologic purposes, this does not accurately characterize enough members of a genetically heterogeneous bacterial population. The aims of this work were to evaluate the genetic diversity of 45 type Ia GBS strains isolated in Brazil by pulsed-field gel electrophoresis as well as to evaluate antimicrobial susceptibility profiles and identify virulence genes. Twenty-four strains were assigned to cluster A. All strains under study contained the hylB and scpB genes. The bca gene was detected in only 10 strains and none of the streptococci carried the bac gene. Thirty-nine strains were resistant to tetracycline.

Memórias do Instituto Oswaldo Cruz, 1995

Memórias do Instituto Oswaldo Cruz, 2011

Streptococcus agalactiae isolates are more common among pregnant women, neonates and nonpregnant ... more Streptococcus agalactiae isolates are more common among pregnant women, neonates and nonpregnant adults with underlying diseases compared to other demographic groups. In this study, we evaluate the genetic and phenotypic diversity in S. agalactiae strains from Rio de Janeiro (RJ) that were isolated from asymptomatic carriers. We analysed these S. agalactiae strains using pulsed-field gel electrophoresis (PFGE), serotyping and antimicrobial susceptibility testing, as well as by determining the macrolide resistance phenotype, and detecting the presence of the ermA/B, mefA/E and lnuB genes. The serotypes Ia, II, III and V were the most prevalent serotypes observed. The 60 strains analysed were susceptible to penicillin, vancomycin and levofloxacin. Resistance to clindamycin, chloramphenicol, erythromycin, rifampin and tetracycline was observed. Among the erythromycin and/or clindamycin resistant strains, the ermA, ermB and mefA/E genes were detected and the constitutive macrolides, lincosamides and streptogramin B-type resistance was the most prevalent phenotype observed. The lnuB gene was not detected in any of the strains studied. We found 56 PFGE electrophoretic profiles and only 22 of them were allocated in polymorphism patterns. This work presents data on the genetic diversity and prevalent capsular serotypes among RJ isolates. Approximately 85% of these strains came from pregnant women; therefore, these data may be helpful in developing future prophylaxis and treatment strategies for neonatal syndromes in RJ.

Journal of General Virology, 1976

Internal proteins, synthesized in T2-infected Eseherichia coli 8 cells were recovered from bacter... more Internal proteins, synthesized in T2-infected Eseherichia coli 8 cells were recovered from bacterial membranes during the early stages of infection. Approx. i5 rain after the onset of infection, T2 and T4 internal proteins were released from the bacterial membranes and sedimented along with newly synthesized phage DNA. Internal protein-DNA complexes were also obtained by chromatography on hydroxylapatite columns. Internal proteins were not released from bacterial membranes after infection with amber mutants defective in genes 2 I, 22 and 23. It has been suggested that these complexes are intermediates in T-even phage morphogenesis.

Journal of General Virology, 1976

Polypeptides of low tool. wt. have been extracted from T4 coliphages and from Escherichia coli B ... more Polypeptides of low tool. wt. have been extracted from T4 coliphages and from Escherichia coli B cells infected with a wild type and various amber mutants of bacteriophage T4. Six peptides were fractionated by chromatography on phosphocellulose: three of them were cleaved from proteins synthesized late in infection and related to phage head. The remaining three peptides have been shown to arise from early-labelled phage-induced proteins. Two of these six small petide fragments were found in the head of the T4 phage.

Journal of Ethnopharmacology, 1995

A fraction obtained from the culture fluids ofPycnoporus sanguineus fungus was shown to contain a... more A fraction obtained from the culture fluids ofPycnoporus sanguineus fungus was shown to contain a compound with biological activity against strains of Escherichia coil, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and members of the genus Streptococcus. The fraction was clearly more active on Gram-positive cocci than on Gram-negative bacilli.

Journal of Antimicrobial Chemotherapy, 1995

Upon the addition of beta-lactam antibiotics at concentrations that caused a 50% reduction in the... more Upon the addition of beta-lactam antibiotics at concentrations that caused a 50% reduction in the dry weight, beta-haemolytic streptococci produced increased amount of rhamnose, though the hexosamine content remained unchanged. These sugars are components of C-carbohydrate. Sialic acid content also increased in group B streptococcal surfaces and penicillin treatment generated new accessible surface sialic acid residues.