Joel E. Mortensen

In Vitro Activity of Oral Antimicrobial Agents Against Clinical Isolates of Pasteurella multocida

Pasteurella multocida causes a wide variety of infections and is the most common localized soft tissue infection after animal bite injuries. Penicillin or amoxicillin has been considered agent of choice for therapy. Reported beta-lactamase production by some isolates, the therapeutic dilemma of the penicillin allergic patient, and the polymicrobial nature of some infections led to this study of alternate antimicrobial agents. The in vitro activity of ampicillin, amoxicillin/clavulanate, cefprozil, cefuroxime, erythromycin, clarithromycin, trimethoprim/sulfamethoxazole, ciprofloxacin, and tetracycline were compared to penicillin against 73 geographically diverse isolates of P. multocida from human infections collected since 1991. MIC90 (microgram/mL) were as follows: penicillin < or = 0.06; ampicillin < or = 0.5; amoxicillin/clavulanate < or = 0.5; cefaclor 1.0; cefprozil 1.0; cefpodoxime 0.06; cephalothin 2.5; cefuroxime < or = 0.25; erythromycin 2.0; azithromycin 1.0; clarithromycin 4.0; trimethoprim/sulfamethoxazole < or = 0.5/9.5; ciprofloxacin < or 0.25; tetracycline < or = 2.0. No beta-lactamase producing isolates were found in this study. This in vitro study has identified alternate oral agents to penicillins that may be appropriate for therapy of P. multocida infections.

A plasmid mediating production of a beta-lactamase by Stenotrophomonas maltophilia

Abstract To delineate the mechanisms that contribute to the high level of antimicrobial resistance often demonstrated by Stenotrophomonas maltophilia , DNA was purified from five clinical isolates and analyzed for the presence of plasmid DNA. Purified plasmid DNA from a single isolate contained a 6.5-kb plasmid, designated pXM222, and a 5.6-kb plasmid, designated pTHB. Transformation of pTHB into Escherichia coli K-12 HB101 resulted in the expression of resistance to the penicillins and to cefazolin.

Antibiotic susceptibility in Streptococcus suis

Abstract This study was undertaken to begin characterization of naturally occurring strains of Streptococcus suis with differing plasmid and macrolide susceptibility profiles. A total of 49 strains of S suis of human and porcine origin were evaluated. The minimal inhibitory concentration values at which 90% of the strains were susceptible to a given agent demonstrated that the 49 S suis isolates were susceptible to ampicillin, seven cephalosporins, vancomycin, trimethoprim-sulfamethoxazole, and gentamicin. Moderate susceptibility to penicillin and moxalactam was seen, but the isolates were resistant to erythromycin, clindamycin, and tetracycline. Of six selected strains, four contained 6–9-kb plasmids and were erythromycin resistant, while two had no plasmids and were erythromycin susceptible.

Comparative in vitro activity of furopenem against aerobic bacteria isolated from pediatric patients

The in vitro activity of the oral penem furopenem (WY-49605, 545555, SUN5555, and ALP201) was tested against clinical bacteria isolated from pediatric patients. Furopenem was compared with clarithromycin, cefpodoxime, amoxicillin, amoxicillin-clavulanate, cefaclor, cefixime, and cefuroxime. Furopenem demonstrated consistent activity against Escherichia coli [minimum inhibitory concentration (MIC90) = 1.0 microgram/ml)] Klebsiella pneumoniae (MIC90 = 2.0 micrograms/ml), Salmonella enteriditis and Shigella spp. (MIC90 = 1.0 microgram/ml), and beta-lactamase-positive or -negative Haemophilus influenzae (MIC90 = 1.0 microgram/ml) and Moraella catarrhalis (MIC90 = 1.0 microgram/ml). Furopenem was also active against a number of the Gram-positive organisms tested including methicillin-susceptible Staphylococcus aureus and penicillin-susceptible Streptococcus pneumoniae. These results suggest a potential application for this agent in the treatment of children as outpatients.

DETECTION OF FUNGEMIA IN A PEDIATRIC POPULATION

Abstract Fungemia is an important cause of morbidity in compromised hosts and in children who have indwelling vascular catheters. Several new systems for culturing blood have been introduced during the past few years. To assess the need for a separate blood culture system for the recovery of fungi, we reviewed the results of all blood cultures performed during a 24-month period. A total of 17,428 blood samples were cultured: 15,855 using the Septi-Chek system and 1573 using the Isolator system. Seventy-four fungal isolates were recovered from 72 samples; 38 were considered clinically significant. In 47 cases, both blood culture systems were inoculated; both systems showed positive results in 14 of 18 episodes of clinically significant fungemia. Contaminants were recovered more frequently from samples processed using the Isolator system. In our laboratory and with our patient population, the Septi-Chek system was equivalent to the Isolator in detecting fungemia, while Septi-Chek had the advantage of allowing growth of fewer contaminants.

A Low-Copy Number Plasmid Mediating β-Lactamase Production by Xanthomonas Maltophilia

To delineate the mechanisms contributing to the high level of antimicrobial resistance often demonstrated by Xanthomonas maltophilia, plasmid DNA was isolated from 5 clinical isolates and analyzed. Purified plasmid DNA from a single isolate contained a 6.5 kb plasmid (pXM222) and a 5.6 kb plasmid, (pTHB). Transformation of pTHB into E. coli HB101 resulted in the expression of resistance to all penicillins tested and cefazolin.

Streptococcus Pyogenes : Resistant, Tolerant, Neither or Both?

The role of Streptococcus pyogenes in pharyngitis as well as its importance in the sequelae of that infection is well known and a constant concern. However, in the last several years, the number of life-threatening infections caused by S. pyogenes, such as toxic shock-like syndrome and severe invasive disease, have increased the concern about this organism.1,2,3

The Antimicrobial Susceptibility of Streptococcus Pyogenes Isolates from the Philadelphia Area

Since the early 1980’s, reports from North America, Australia, Japan and Europe have indicated that Streptococcus pyogenes strains are becoming increasingly resistant to several antimicrobial agents.1–6 In order to determine if an increase in antimicrobial resistance was present in S. pyogenes from the greater Philadelphia area isolates from eleven Philadelphia hospitals, were collected and tested against penicillin, ampicillin, cephalothin, clindamycin, erythromycin, rifampin, vancomycin and ciprofloxacin.

Is One Laboratory in Town Enough

Hospitals have had enormous economic and sociological importance in the United States. The roughly six thousand community hospitals in the United States account for more than 4% of the gross national product. Hospitals directly employ more than three million persons. In addition, hundreds of thousands of people are employed providing goods and services to the hospital industry, along with more than 300,000 physicians.1,2,4