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.

Escherichia coli↗

PubMedDate not supplied

[Viridans streptococci in human infections: identification and susceptibility to antibiotics].

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.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Group D streptococci in human infections: identification and sensitivity to antibiotics (author's transl)].

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).

Anti-Bacterial Agents↗

PubMedDate not supplied

[Characteristics of "Streptococcus mutans" from endocarditis and susceptibility to antimicrobial agents (author's transl)].

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.

Endocarditis, Subacute Bacterial↗

PubMedDate not supplied

[R plasmids incompatibility groups in epidemic Salmonella (author's transl)].

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.

Anti-Bacterial Agents↗