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C Thornsberry

Publications and source records attributed to C Thornsberry.

At least 55 records · Page 3Linked to original sources
PubMed1996

Emerging resistance in clinically important gram-positive cocci.

In the first half of the decade of the 1990s, we in the United States have seen the emergence and escalation of substantial antimicrobial resistance in medically important gram-positive cocci. The incidence of methicillin resistance of Staphylococcus aureus continues to increase (now 18%), resulting in many more isolates that are multiply resistant; all S aureus isolates are still susceptible to vancomycin. Enterococci, particularly Enterococcus faecium, have increasingly developed resistance to penicillin, gentamicin, streptomycin, and vancomycin (the last plasmid-mediated). More than a fourth of Streptococcus pneumoniae strains are now resistant to penicillin, and these strains tend to be multiply resistant, including to cephalosporins and macrolides.

Drug Resistance, Microbial↗
PubMed1995

Subgingival bacteria--comparison of culture results in dogs and cats with gingivitis.

Aerobic and anaerobic subgingival bacteria were cultured and identified from 49 dogs and 40 cats with spontaneous gingivitis. The most common organisms were gram-negative anaerobes (37% of canine isolates and 39% of feline isolates) and gram-positive aerobes (36% of canine isolates and 29% of feline isolates). No major differences were found between the subgingival floras of dogs and cats with gingivitis.

Animals↗
PubMed1995

Antimicrobial susceptibility of subgingival bacterial flora in dogs with gingivitis.

The aerobic and anaerobic flora from gingival pockets of 49 dogs with severe gingivitis and periodontitis were cultured. The susceptibility of each isolate to four antimicrobial agents currently approved for veterinary use in the USA (amoxicillin-clavulanic acid; clindamycin; cefadroxil; and enrofloxacin) was determined. Amoxicillin-clavulanic acid (Clavamox Pfizer Animal Health) had the highest in-vitro susceptibility against all isolates (96%), all aerobes (94%) and all anaerobes (100%) tested. For gram-negative aerobes, enrofloxacin (Baytril, Bayer Corp.) had the highest in-vitro susceptibility activity. For bacteria associated with treatment of gingivitis, which typically are mixed aerobic/anaerobic and gram-positive/gram-negative organisms, the antimicrobial of choice for clinical use based on these susceptibility tests is amoxicillin-clavulanic acid.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed1995

Antimicrobial susceptibility of subgingival bacterial flora in cats with gingivitis.

The aerobic and anaerobic flora from gingival pockets of 40 cats with established gingivitis were cultured. The susceptibility of each isolate to four antimicrobial agents currently approved for use in cats (amoxicillin-clavulanic acid; clindamycin; cefadroxil; enrofloxacin) was determined. Amoxicillin-clavulanic acid (Clavamox) had the highest in-vitro susceptibility against all isolates (92%) and all anaerobes (99% [co-equal with clindamycin]) tested; enrofloxacin (Baytril) had the highest in-vitro susceptibility against all aerobes (90%) tested.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed1994

Susceptibility of clinical bacterial isolates to ciprofloxacin in the United States.

In 1990-1991, in a national surveillance study of bacterial resistance, ciprofloxacin data from geographic and demographically diverse institutions were collected. Most of the isolates were from hospitalized patients. Ciprofloxacin susceptibility was obtained on 154,689 clinical isolates comprising 48 genera and 128 species or groups; 60.2% of the species or groups and 62.3% of the isolates were gram-negative. MIC tests and identification tests also were performed on 12,012 of these isolates, which had been submitted to our in-house laboratory. For all surveillance isolates, 88.2% were susceptible, 4.6% were moderately susceptible, and 7.2% were resistant to ciprofloxacin. Most isolates (96.2%) of the surveillance Enterobacteriaceae were susceptible to ciprofloxacin, as were 87.7% of the Pseudomonas aeruginosa (7.8% resistant). A majority of the methicillin-susceptible strains of Staphylococcus aureus were susceptible (95.7%) or moderately susceptible (1.4%) to ciprofloxacin. But a majority of methicillin-resistant isolates were resistant (76.4%) to ciprofloxacin. Most of the pneumococci (96.5%) were susceptible or moderately susceptible to ciprofloxacin with 92.7% of these isolates having MICs of 1 mg/l (susceptible) or 2 mg/l (moderately susceptible). The ciprofloxacin data for the isolates tested in our in-house laboratory generally confirmed the susceptibility rates of those from the surveillance data. This study shows that, with the exception of methicillin-resistant staphylococci, ciprofloxacin has retained a high level of activity against most bacterial pathogens.

Bacterial Infections↗
PubMed1994

Epidemiology of staphylococcal infections--a USA perspective.

Data collected from the National Nosocomial Infection Surveillance show that Gram-positive organisms, and Staphylococcus aureus in particular, are a major cause of nosocomial infections, especially wound infections, pneumonia and bacteraemia. Currently in the United States, approximately 18% of S. aureus isolates show intrinsic resistance to methicillin.

Anti-Bacterial Agents↗
PubMed1993

A comparative study of the in-vitro activity of cefepime and other antimicrobial agents against penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae.

Using the national surveillance programme of USA hospitals, we selected 162 strains of Streptococcus pneumoniae for sensitivity testing using the NCCLS breakpoints for benzylpenicillin and the oxacillin discs screen test. Included in the group of isolates were 85 relatively penicillin-resistant and 33 penicillin-resistant strains. The activity of cefepime, a new cephalosporin, was compared with other cephalosporins and penicillins as well as some non-beta-lactam antimicrobials. Imipenem was the most active agent but, cefepime, cefotaxime, ceftriaxone and ciprofloxacin were only slightly less active. The least active agents were ceftazidime, cefuroxime, piperacillin/tazobactam and ticarcillin/clavulanate. Cefepime is a potential alternative treatment to penicillin, particularly when penicillin-resistant and relatively penicillin-resistant S. pneumoniae are encountered. The clinical importance of screening for penicillin resistance by the use of the oxacillin disc is emphasized.

Anti-Bacterial Agents↗
PubMed1993

In-vitro activity of cefepime and other antimicrobials: survey of European isolates.

Cefepime, a new cephalosporin which has a broad-spectrum of activity was tested in vitro against 1961 Gram-positive and Gram-negative clinical isolates obtained from European hospitals. Cefepime was highly active against Gram-negative organisms, inhibiting over 94% of strains tested. The overall susceptibility rate for cefepime against all isolates was 81%. Cefepime was more active than any of the third-generation cephalosporins tested against species capable of producing type I beta-lactamases, e.g. Enterobacter cloacae, Citrobacter freundii, and Enterobacter aerogenes. The activity of cefepime against Pseudomonas aeruginosa was similar to that of ceftazidime and substantially greater than those of cefotaxime and ceftriaxone. All cephalosporins except ceftazidime exhibited high activity against methicillin-susceptible Staphylococcus aureus but poor activity was observed against methicillin-resistant strains. Overall susceptibility to cefepime is lower in Europe than it is in North America.

Anti-Bacterial Agents↗
PubMed1993

Activity of pirlimycin against pathogens from cows with mastitis and recommendations for disk diffusion tests.

Pirlimycin is an analog of clindamycin that will be recommended for therapy of bovine mastitis. It has good activity against staphylococci and streptococci, the major pathogens for bovine mastitis. Five hundred and thirty bacterial isolates recovered from cows with mastitis were studied to confirm the spectrum of activity and to develop recommendations for susceptibility testing. Pirlimycin is not active against isolates of Enterobacteriaceae, it varies in its activity against enterococci, and it is active against veterinary isolates of streptococci (MIC for 50% of strains tested, < or = 0.03 to 0.06 microgram/ml) and staphylococci (MIC for 50% of strains tested, 0.25 to 1.0 microgram/ml). On the basis of levels of drug attained in the milk with recommended dosing schedules, we chose MIC breakpoints of < or = 2 micrograms/ml for susceptibility and > or = 4 micrograms/ml for resistance. We also recommended a disk diffusion test using a disk containing 2 micrograms/ml and breakpoints of < or = 12 mm for resistance and > or = 13 mm for susceptibility.

Animals↗
PubMed1992

E-Test symposium.

Explore the source record for details and available documents.

Bacteria↗
PubMed1992

Review of the in vitro antibacterial activity of cefprozil, a new oral cephalosporin.

Cefprozil is a newer oral cephalosporin with a spectrum of activity against organisms that include gram-positive and gram-negative pathogens. A review of published data shows that cefprozil is active (susceptibility, less than or equal to 8 micrograms/mL; moderate susceptibility, 16 micrograms/mL; resistance, greater than or equal to 32 micrograms/mL) against gram-positive species such as streptococci, methicillin-susceptible staphylococci, and Listeria monocytogenes; it may have marginal activity against some enterococci. Among the gram-negative species, cefprozil has activity against Escherichia coli, Proteus mirabilis, Citrobacter diversus, Klebsiella pneumoniae, Klebsiella oxytoca, Haemophilus influenzae, and Moraxella catarrhalis. For anaerobic species, cefprozil has activity against clostridial species, including Clostridium difficile, peptostreptococci, and possibly Bacteroides melaninogenicus and Eubacterium. The activity of cefprozil is generally greater than that of cephalexin and generally similar to that of cefaclor. In these reports, cefprozil showed more in vitro activity than cephalexin and cefaclor against penicillin-resistant pneumococci, penicillin-resistant viridans streptococci, beta-lactamase-positive methicillin-susceptible Staphylococcus aureus, and C. difficile, although the clinical significance of some of these differences has yet to be studied.

Cephalosporins↗
PubMed1992

Antimicrobial susceptibility patterns of common and unusual species of enterococci causing infections in the United States. Enterococcal Study Group.

We collected 705 isolates of enterococci (1 per patient) from cultures of a variety of anatomic sites from patients at eight tertiary-care hospitals in six geographic regions of the United States. A total of 632 (90%) Enterococcus faecalis, 58 (8%) E. faecium, 5 E. gallinarum, 4 E. avium, 3 E. casseliflavus, 1 E. raffinosus, and 1 E. hirae isolate and 1 biochemical variant of E. faecalis were identified; 606 (86%) of these isolates were associated with clinical infections. The most common sites of isolation were the urinary tract (402 [57%]), nonsurgical wounds (94 [13%]), the bloodstream (74 [10%]), and surgical wounds (62 [9%]). High-level resistance to gentamicin or streptomycin or both was detected in 265 (38%) of the isolates. We identified two E. faecalis isolates resistant to vancomycin (MICs, 32 and 128 micrograms/ml) and 11 beta-lactamase-producing E. faecalis isolates. E. faecium isolates were significantly more resistant than E. faecalis isolates to penicillin, ampicillin, piperacillin, imipenem, and ciprofloxacin (P less than 0.001). The MICs for the 15 non-E. faecalis, non-E. faecium enterococci indicated variable resistance to ciprofloxacin and the penicillins. Antimicrobial susceptibility patterns vary among species of enterococci, and these organisms, while commonly resistant to high-level aminoglycosides, can also acquire resistance to vancomycin or the ability to produce beta-lactamase. Because of these diverse antimicrobial resistance mechanisms, successful treatment and control of enterococcal infections with current antimicrobial agents are becoming increasingly difficult.

Adolescent↗
PubMed1992

Cefaclor AF: correlation of microbiology and clinical outcome.

Cefaclor is active against Haemophilus influenzae and Moraxella catarrhalis in addition to the pathogens typically susceptible to first-generation cephalosporins. Cefaclor advanced formulation (cefaclor AF) provides the opportunity for once or twice daily dosing of this agent. Clinical trials using cefaclor AF have been carried out in a number of centres on bacterial infections of the respiratory tract, the urinary tract and the skin. In vitro susceptibility tests on selected pathogens from the clinical trials were carried out according to National Committee for Clinical Laboratory Standards recommendations, generally with excellent agreement between in vitro and in vivo response.

Bronchitis↗
PubMed1991

Antimicrobial resistance of pneumococci in children with acute lower respiratory tract infection in Pakistan.

87 strains of Streptococcus pneumoniae isolated during three winter seasons (1986-89) from the blood of children with acute lower respiratory tract infection (ALRI) in Pakistan were serotyped and tested for susceptibility to a range of antimicrobial agents. 97% of isolates were resistant to at least one antimicrobial drug. 62% had decreased susceptibility to co-trimoxazole (trimethoprim/sulphamethoxazole) (31% were fully resistant) and 39% were resistant to chloramphenicol. All isolates were susceptible to erythromycin, cefaclor, cephalothin, ceftriaxone, cefuroxime, rifampicin, vancomycin, and clindamycin. 29% of isolates were neither vaccine types nor vaccine-related types. Serotype distribution and antimicrobial susceptibility varied significantly during the three winter seasons. No single serotype was found in all three winters. The findings highlight the need for surveillance of antimicrobial resistance and serotype distribution of S pneumoniae in developing countries as a guide both to the choice of agent for treatment of pneumococcal infections, especially ALRI, and to the formulation of new pneumococcal conjugate vaccines for use in young children.

Child, Preschool↗
PubMed1991

Comparison of the E Test to agar dilution, broth microdilution, and agar diffusion susceptibility testing techniques by using a special challenge set of bacteria.

The E Test (AB Biodisk, Solna, Sweden) is a new method for performing antimicrobial susceptibility tests. It consists of an impervious carrier (5- by 50-mm strip) with a predefined antimicrobic gradient which is placed on an inoculated agar plate and processed like a disk diffusion test. Results are generated directly as MICs from a continuous concentration gradient covering 15 twofold dilutions, and MICs are read where the edge of the inhibition zone intersects the strip. We compared the E Test with disk diffusion, broth microdilution, and agar dilution tests by using a challenge set of 195 gram-positive and gram-negative bacteria for 14 antimicrobial agents. Also, disk diffusion, broth microdilution, and agar dilution tests were compared with each other. All test method comparisons gave greater than 94% agreement for the category of susceptibility. The E Test category agreement with disk diffusion and broth microdilution was 95.1%, and with agar dilution it was 95.2%. The E Test results were as reliable as the results obtained by the standard antimicrobial susceptibility testing methods.

Agar↗
PubMed1990

Disk diffusion susceptibility testing of Haemophilus influenzae using haemophilus test medium.

A three-center collaborative study was performed with the aim of determining the reproducibility of disk diffusion and broth microdilution susceptibility tests of Haemophilus influenzae with 19 different antimicrobial agents using a newly described medium, Haemophilus Test Medium. The results of both methods were found to be highly reproducible. Using Haemophilus Test Medium, inhibitory zone diameters and MICs were then determined for 150 test strains of Haemophilus influenzae, selected with an emphasis on known mechanisms of resistance. Regression analysis of zone diameter-MIC comparisons was used to define zone diameter interpretive criteria and MIC correlates for Haemophilus Test Medium disk diffusion tests performed with Haemophilus spp. for the following antimicrobial agents: ampicillin, amoxicillin/clavulanate, ampicillin/sulbactam, cefaclor, cefuroxime, cefamandole, ceftriaxone, cefotaxime, ceftizoxime, ceftazidime, cefixime, trimethoprim/sulfamethoxazole, rifampin, chloramphenicol, tetracycline, imipenem, aztreonam and ciprofloxacin.

Anti-Bacterial Agents↗
PubMed1990

Antimicrobial susceptibility of vancomycin-resistant Leuconostoc, Pediococcus, and Lactobacillus species.

Eighty-five strains of vancomycin-resistant gram-positive bacteria from three genera, Leuconostoc, Pediococcus, and Lactobacillus, were tested to determine susceptibility to 24 antimicrobial agents by broth microdilution and to 10 agents by disk diffusion. The MICs of vancomycin and teicoplanin ranged from 64 to greater than 512 micrograms/ml; however, the MICs of daptomycin, a new lipopeptide, were all less than or equal to 0.25 micrograms/ml. None of the organisms were resistant to imipenem, minocycline, chloramphenicol, gentamicin, or daptomycin. The MICs of penicillin were in the moderately susceptible range for all but three strains. Susceptibility to the other agents varied by genus and, in some cases, by species. When disk diffusion results were compared with MICs for drugs recommended for streptococci by the National Committee for Clinical Laboratory Standards, Villanova, Pa., few very major or major errors were obtained, but the number of minor errors was 19.3%. Therefore, we recommended that MIC testing be used instead of disk diffusion testing for these organisms.

Anti-Bacterial Agents↗