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Robert C Moellering

Publications and source records attributed to Robert C Moellering.

23 records · Page 2Linked to original sources
PubMed2002

Linezolid resistance in Staphylococcus aureus: characterization and stability of resistant phenotype.

Linezolid is an important therapeutic option for treatment of infections caused by glycopeptide- and beta-lactam-resistant gram-positive organisms. Linezolid resistance is caused by mutations within the domain V region of the 23S ribosomal RNA (rRNA) gene, which is present in multiple copies in most bacteria. Among clinical Staphylococcus aureus isolates, there has been only 1 reported case of linezolid resistance. In the present study, this isolate was further characterized by determination of the number of mutant 23S rRNA copies, assessment of the stability of the resistant phenotype, and comparison of its growth characteristics with those of linezolid-susceptible S. aureus. All 5 copies of the 23S rRNA gene contained a G2576U mutation in the domain V region. After serial passage on antibiotic-free medium, the isolate maintained resistance to high concentrations of linezolid. Compared with 2 linezolid-susceptible S. aureus isolates, the linezolid-resistant S. aureus isolate demonstrated no significant differences in in vitro growth characteristics.

Acetamides↗
PubMed2002

The continuing challenge of lower respiratory tract infections.

Lower respiratory tract infections have been a major cause of morbidity and mortality among humans since the dawn of history. The initial hope that the era of antibiotics would remove this scourge has been replaced by the more realistic view that although antimicrobial agents represent a major therapeutic advance, they have not yet solved all of the problems of lower respiratory tract infections. The pneumococcus, for example, causes mortality in a certain number of patients despite antimicrobial therapy. An even greater challenge is being imposed by the emergence of antimicrobial resistance among important bacterial pathogens, especially Streptococcus pneumoniae.

Centers for Disease Control and Prevention, U.S.↗
PubMed2002

Accessory gene regulator (agr) locus in geographically diverse Staphylococcus aureus isolates with reduced susceptibility to vancomycin.

The majority of infections with glycopeptide intermediate-level resistant Staphylococcus aureus (GISA) originate in biomedical devices, suggesting a possible increased ability of these strains to produce biofilm. Loss of function of the accessory gene regulator (agr) of S. aureus has been suggested to confer an enhanced ability to bind to polystyrene. We studied agr in GISA, hetero-GISA, and related glycopeptide-susceptible S. aureus isolates. All GISA strains from diverse geographic origins belong to agr group II. All GISA strains were defective in agr function, as demonstrated by their inability to produce delta-hemolysin. Hetero-GISA isolate A5940 demonstrated a nonsense mutation in agrA that was not present in a pulsed-field gel electrophoresis-indistinguishable vancomycin-susceptible isolate from the same patient. Various other agr point mutations were noted in several clinical GISA and hetero-GISA isolates. A laboratory-generated agr-null strain demonstrated a small but reproducible increase in vancomycin heteroresistance after growth in vitro in subinhibitory concentrations of vancomycin. This was not seen in the isogenic agr group II parent strain in which agr was intact. The in vitro bactericidal activity of vancomycin was attenuated in the agr-null strain compared to the parent strain. These findings imply that compromised agr function is advantageous to clinical isolates of S. aureus toward the development of vancomycin heteroresistance, perhaps through the development of vancomycin tolerance.

Amino Acid Sequence↗
PubMed2002

Antimicrobial-associated acute hepatitis.

Recently, the case history of a 44-year-old woman who experienced acute hepatitis subsequent to therapy for chronic sinusitis was reviewed. The patient sequentially was administered clarithromycin, levofloxacin, amoxicillin-clavulanate, and gatifloxacin. Her adverse events were attributed definitively to gatifloxacin, a surprising conclusion because many other possible causes of hepatitis existed in this case. Not ruled out as potential causes of the clinical and laboratory adverse events were hepatitis other than hepatitis A or B. Other antimicrobials administered were dismissed. In particular, extended treatment with amoxicillin-clavulanate has been clearly linked to hepatotoxic effects that may occur long after therapy begins. Thus, while we agree that physicians must be aware of the potential for antimicrobial hepatotoxicity, we believe that this case study is not a solidly documented case of hepatitis attributable to gatifloxacin and overlooks other possible causes of acute hepatitis of which prescribers should be aware.

Adult↗