[Viridans streptococci in human infections: identification and susceptibility to antibiotics]. / Les streptocoques non groupables dans les infections humaines: identification et sensibilité aux antibiotiques.

A method for the speciation of viridans streptococci (devoided of group antigens) is described. The major identification criteria are based on the reaction of a series of biochemical tests such as acid production in lactose, inuline, raffinose, mannitol and sorbitol, hydrolysis of arginine, esculin and Na hippurate, and production of polysaccharides in 5% sucrose media. A total of 460 strains were isolated from human specimens and identified as follows: 118 Streptococcus mitis, 102 S. sanguis II, 75 S. Sanguis I, 87 S. milleri (Streptococcus MG-intermedius), 28 S. mutans, 25 S. salivarius, 14 S. morbillorium, 2 S. uberis and 9 unspeciated. Susceptibility to antibiotics was studied for 318 strains: 63% of them were susceptible to all drugs tested; 37% of the strains were resistant to one or several antibiotics as follows: 34% to tetracycline, 8.5% to macrolides and related drugs, 5.3% to streptomycin and/or kanamycin (MIC greater than 2,000 micrograms/ml), 5% to penicillin (MIC = 1-4 micrograms/ml) and 4% to chloramphenicol.

[Antibiotic resistance genetic basis of human origin streptococci (author's transl)]. / Support génétique de la résistance aux antibiotiques chez les streptocoques d'origine humaine.

One hundred strains of group A, B, C, D (S faecalis, S. faecium, S. bovis) F, G, S. pneumoniae and viridans streptococci were studied. All these strains were clinical isolates from infective endocarditis and fron upper respiratory, skin, genital and urinary tract infections. These stains were resistant to one or several antibiotics : tetracycline, macrolide and related drugs, chloramphenicol, aminoglycosides (high-level resistance to streptomycin, kanamycin, gentamicin), and penicillin. Conjugative transfer of antibiotic resistance markers (except penicillin) into streptococcal recipients was obtained at a high frequency (10(-1) to 10(-4)) for 12 strains and at a low frequency (10(-5) to 10(-8)) for 29 strains. R plasmids carrying various groups of resistance markers were isolated with different molecular weights. Enzyme restriction analysis showed the existence of different molecular species of streptococcal plasmids. All attempts to detect extrachromosomal DNA in 17 wild-type strains and in the corresponding transconjugants were unsuccessful.

Conjugative R plasmids in Streptococcus faecium (group D).

Ten isolates of Streptococcus faecium were found to be resistant to penicillin, tetracycline, macrolides and related drugs, streptomycin, and kanamycin, and four strains were resistant to chloramphenicol. Six of these 10 strains transferred all their resistance markers (except penicillin) by conjugation at a low frequency (10(-7) to 10(-9)). Several plasmids of different molecular weights were found in each of the wild-type strains. In 5 of 11 transconjugant strains, R plasmids were detected which had molecular weights identical to those of the plasmids found in the corresponding donor strain. Each of the six other transconjugants harbored one plasmid with a size different from those found in the corresponding donor strain, suggesting the occurrence of molecular events during or after conjugative transfer. None of the five tetracycline-resistant transconjugants contained detectable satellite DNA, HindIII restriction enzyme fingerprints of S. faecium resistance plasmids were different from the HindIII patterns of macrolide, aminoglycoside, and tetracycline resistance plasmids from other strains of streptococci.

High-level aminoglycoside resistance in group A, B, G, D (Streptococcus bovis), and viridans streptococci.

Of 20 clinical isolates of group A, B, G, D (Streptococcus bovis), and viridans streptococci, 5 transferred their antibiotic resistance markers into streptococcal recipients at a low frequency (10(-4) to 10(-8)) in the apparent absence of extrachromosomal elements. All strains carried genetic markers for high-level resistance to streptomycin, kanamycin, neomycin, lividomycin A, and ribostamycin, as well as resistance to macrolides and related drugs, tetracycline, and chloramphenicol.

Conjugative R plasmids in group C and G streptococci.

Two streptococcal isolates of groups C and G harbored conjugative R plasmids with molecular weights of 17 X 10(6) (pIP646) and 20 X 10(6) (pIP920). These plasmids carried genetic markers for resistance to macrolides and related drugs, as well as to chloramphenicol (pIP920), and have very similar HindIII restriction enzyme patterns.

[Group D streptococci in human infections: identification and sensitivity to antibiotics (author's transl)]. / Les streptocoques du groupe D dans les infections humaines: identification et sensibilité aux antibiotiques.

A method for the speciation of group D streptococci is described. A major criterion for identification is the reaction of antigenic extracts against streptococcal group D antisera. In addition, a series of biochemical tests is used: bile-esculine, resistance to 6.5% sodium chloride and potassium tellurite, acid production in mannitol, sorbitol and raffinose, hydrolysis of starch and arginine, and production of dextran. A total of 184 strains was isolated from human material and identified as follows: 104 S. faecalis, 18 S. faecium, 8 S. durans, 2 S. avium, 51 s. bovis and 1 unspeciated. The sensitivity to antibiotics was studied for 141 strains: 34% were sensitive, 23% were singly resistant to tetracycline and 43% were multiply resistant (tetracycline, macrolides and related drugs, high-level resistance to aminoglycosides and to chloramphenicol).

Conjugative transfer of multiple antibiotic resistance markers in Streptococcus pneumoniae.

Two antibiotic-resistant isolates of Streptococcus pneumoniae were investigated for conjugative transfer of their drug resistance markers into streptococcal (groups B and D) and pneumococcal (encapsulated and non-encapsulataed) recipients. Of these, 7 wild-type donor pneumococci transferred all their resistance markers (except Pc [penicillin], Su [sulfonamide], and Tp [trimethoprim]) into group D Streptococcus and non-encapsulated S. pneumoniae recipients at a low frequency (10(-5) to 10(-6)). The resistance markers transferred were Tc (tetracycline); Tc and Cm (chloramphenicol); Tc and MLS (macrolides, lincosamides, and streptogramin B); Tc, MLS, Km (kanamycin), and Cm. The transconjugants obtained retransferred their resistance markers into appropriate streptococcal or pneumococcal recipients or both. The resistance markers of streptococcal transconjugants could not be cured by chemical agents. All attempts to detect extra-chromosomal deoxyribonucleic acid from pneumococcal or streptococcal transconjugants were unsuccessful. The molecular weight of a streptococcal conjugative R plasmid (pIP501) was investigated after transfer into the non-encapsulated S. pneumoniae recipient and was found to be similar to that of the wild-type group B Streptococcus host (20 x 10(6)).

High-level, plasmid-borne resistance to gentamicin in Streptococcus faecalis subsp. zymogenes.

Each of three isolates of Streptococcus faecalis subsp. zymogenes harbored three R plasmids and a hemolysin-bacteriocin plasmid. The plasmids carried by one of these strains were physically characterized after their conjugative transfer. In each strain one of the plasmids carried genetic markers for resistance to gentamicin, kanamycin, sisomicin, netilmicin, and tobramycin.

Metabolically deficient dwarf-colony mutants of Escherichia coli: deficiency and resistance to antibiotics of strains isolated from urine culture.

Sixteen metabolically deficient dwarf-colony mutants of Escherichia coli were isolated from urine culture and represented about 2% of all E. coli isolated during the same period. In 14 cases, mutants were isolated from debilitated patients: elderly persons or patients in the terminal stages of a chronic disease. In 15 of these subjects, deficient dwarf-colony mutants appeared to be the true cause of urinary tract infection, since there was leukocyturia and important bacteriuria, and organisms were obtained in pure culture. Study of metabolic deficiencies on Davis synthetic medium and nutritive agar resulted in the identification of eleven deficiencies in cysteine, two in thiamine, two in thymidine, and one in glutamine. Study of resistance to antibiotics revealed that nine were susceptible to all antibiotics, three were resistant to tetracycline alone, two were resistant to two antibiotics (chloramphenicol-tetracycline, streptomycin-tetracycline), and two were resistant to three antibiotics (ampicillin-chloramphenicol-tetracycline, ampicillin-streptomycin-tetracycline). Resistance was coded for by conjugative plasmids in five strains.

Molecular studies and possible relatedness between R plasmids from groups B and D streptococci.

Resistance plasmids isolated from Streptococcus agalactiae (group B) and S. faecalis (group D) have been compared in regard to resistance markers, molecular weight, and DNA-DNA homology. Three of them (pIP501, pIP612, and pIP613) have been found to confer identical (or very similar) resistance patterns (erythromycin, lincomycin, and streptogramin B, respectively) and to have similar molecular weights (19.8 x 10(6), 22.7 x 10(6), and 17.6 x 10(6), respectively) and a high level of DNA-DNA homology in hybridization experiments (90 to 100%). These results are compatible with the view that these plasmids may derive from one common ancestor, and/or that they can be transferred between unrelated Streptococcus strains belonging to the same or different groups.

[Dwarf colony mutants of Escherichia coli: plasmids resistant to antibiotics]. / Mutants déficients à colonies naines d'Escherichia coli: étude des plasmides de résistance aux antibiotiques.

Deficient dwarf colony (DDC) mutants of E. coli K 12, harboring or no resistance plasmids, were obtained in vitro. The R plasmids of parental strains and to DDC mutants were transfered by conjugation to normal colony, and to DDC mutants of E. coli K 12; the frequencies of transfer were similar for all strains studied.

Formation of HfrH-type donor cells as a result of integrative suppression by R-F recombinant plasmids.

Three recombinant plasmids, resulting from recombination between an R plasmid of the FI incompatibility group and the F of HfrH, were introduced in a temperature-sensitive dnaA mutant to isolate Hfr-type-donors. All of the temperature-insensitive clones isolated from two of the three recombinant plasmids had the same origin and transfer pattern as the parental HfrH strain.

[R plasmids incompatibility groups in epidemic Salmonella (author's transl)]. / Groupes d'incompatibilité des plasmides r chez les souches de Salmonella épidémiques.

The susceptibility to antimicrobial agents of 410 strains belonging to six serotypes of epidemic Salmonella (S. wien, S. saint-paul, S. panama, S. heidelberg, S. isangi and S. brandenburg) was studied. Resistance to one or more antibiotics was shown for 228 of these strains. Study of resistance transfer was investigated for 25 multiresistant strains of different epidemic origin. Resistance was coded for by conjugative R plasmids except in the case of S. brandenburg. From 20 strains of Salmonella, 39 plasmids were transferred to E. coli K12. Twenty-nine of these plasmids were classified into 7 incompatibility groups: IncFI, FII, I1, I2, N, C, M. These same groups were also found for 84 R plasmids from different enterobacteria. The "epidemic character" of these Salmonella serotypes does not seem to be associated with carriage of any particular R plasmid.

[Dwarf colony mutants of "Escherichia coli" study of a strain isolated from an uroculture (author's transl)]. / Mutants déficients à colonies naines de Escherichia coli: étude d'une souche thiamine-déficiente isolée d'une uroculture.

A dwarf colony mutant of Escherichia coli was isolated from the urine of a patient with an asymptomatic urinary infection. This dwarf mutant growths poorly (minute transparent colonies) on Trypticase Soja and Mueller-Hinton agar, and requires thiamine concentration of 3 x 10-11 M.

[Characteristics of "Streptococcus mutans" from endocarditis and susceptibility to antimicrobial agents (author's transl)]. / Caractéristiques des souches de Streptococcus mutans isolées d'endocardites subaigues et sensibilité aux antibiotiques.

Strains of Streptococcus mutans were isolated from blood cultures of ten patients with endocarditis. Nine of these patients had a typical clinical picture of subacute bacterial endocarditis, with fever, weakness, heart murmur and multiple positive blood cultures. All the patients had previous valvular heart diseases; only in three cases the initiating event involved some type of dental manipulations which where supposed as the source of infection. The major criteria for recognizing S. mutans were colony morphology on blood agar, characteristic extracellular polysaccharide production in 5% sucrose broth, acid formation in mannitol and sorbitol broth, and the failure of antigenic extracts of S. mutans to react with streptococcal group antisera. The susceptibility to antimicrobial agents was tested by the diffusimetric method with susceptibility disks. All the strains were susceptible to penicillin G, erythromycin, pristinamycin, lincomycin and tetracycline, and resistant to streptomycin and gentamicine.

R plasmids in Streptococcus agalactiae (group B).

Two plasmids determining resistance to tetracycline (RIP500) and to chloramphenicol, erythromycin, lincomycin, and pristinamycin I (RIP501) were isolated from a strain of Streptococcus agalactiae. The frequency-of-resistance loss is very low for RIP500 (<3 x 10(4)) but higher for RIP501 (the efficiency was dependent upon the curing agents and incubation temperature and varied between 0.5 and 96%). Derivatives susceptible to all drugs were also obtained. RIP500 and RIP501 have similar molecular weights (17.9 x 10(6) and 20 x 10(6), respectively) and represent different percentages of total deoxyribonucleic acid (0.4 and 4%, respectively). The number of copies of RIP500 and RIP501 per cell is different, and these plasmids are likely replicated under different kinds of control (stringent and/or relaxed). No plasmid deoxyribonucleic acid was found in a derivative of strain B96 susceptible to all drugs.