The turbidimetric responses of a strain of Escherichia coli K12 to gentamicin and tobramycin were investigated. Both agents showed antibacterial activity below the conventionally measured minimum inhibitory concentration, but exposure to such subinhibitory concentrations of either agent generated a bacterial population which was able to grow in previously inhibitory concentrations at a rate equ...

Between November 1981 and October 1984, 48 of 3,458 clinical isolates of Streptococcus faecalis at the University of Michigan Hospital showed high-level (greater than 2,000 micrograms/ml) resistance to gentamicin, as well as to all other clinically available aminoglycosides. Thirteen percent of clinical isolates in the University of Michigan Hospital currently demonstrate this level of resistan...

background: human exposure to antibiotic resistant bacteria (arb) is a public health concern which could occur in a number of ways. wastewaters seem to play an important role in the dissemination of bacteria and antibiotic resistant genes (args) in our environment. the aim of this study was to evaluate the occurrence of three groups of arb and their resistance genes in hospital and municipal wa...

OBJECTIVE We evaluated the epidemiology of antimicrobial resistance in enterococci from animal farms and the potential relation of resistance to antimicrobial use. METHODS Enterococci from faecal samples from 18 beef cattle, 18 dairy cattle, 18 swine, 13 chicken, and eight turkey farms were prospectively evaluated over a 6 year period from 1998 to 2003. RESULTS We evaluated 1256 isolates of...

Bacterial infections may cause disease and death. Infants and children are often subject to bacterial infections. Antimicrobials kill bacteria protecting the infected patients andreducing the risk of morbidity and mortality caused by bacteria. The antibiotics may lose their antibacterial activity when they become resistant to a bacteria. The resistance to different antibiotics in a bacteria is ...

Four blood culture isolates of Streptococcus mitis were found to be resistant to penicillin (MIC, 16 to 32 micrograms/ml) and gentamicin (MIC, 128 or 1,000 micrograms/ml), and the two antibiotics demonstrated a lack of in vitro synergy. As shown by polymerase chain reaction assays, the structural gene known to encode high-level gentamicin resistance in Enterococcus faecalis, Enterococcus faeciu...

In enterococci, intrinsic low-level resistance to gentamicin does not abolish synergism with a cell wall-active antibiotic while high-level resistance due to acquired aminoglycoside-modifying enzymes does. To study the impact of intermediate levels of resistance to gentamicin (64 < MIC < 500 microg/ml), we selected in vitro three consecutive generations of mutants of Enterococcus faecalis JH2-2...

We cloned DNA fragments of sisomicin-producing Micromonospora inyoensis into Streptomyces plasmid vectors and identified Streptomyces lividans TK24 transformants expressing the M. inyoensis sisomicin-resistance (sisA) gene. The sisA gene was compared to the previously reported Micromonospora purpurea Kan-Gen (kanamycin-gentamicin)-resistance gene. While the restriction endonuclease digestion pa...

Growth in a single broth microdilution well containing gentamicin at a concentration of 500 micrograms/ml predicted high-level resistance to gentamicin (MIC, greater than or equal to 2,000 micrograms/ml) in 505 of 508 clinical isolates of enterococci. Failure to achieve synergistic killing with the combination of penicillin and an aminoglycoside was demonstrated with 100% specificity in 20 stra...