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R N Jones

Publications and source records attributed to R N Jones.

At least 145 records · Page 8Linked to original sources
PubMed2000

Cefditoren activity against nearly 1000 non-fastidious bacterial isolates and the development of in vitro susceptibility test methods.

Cefditoren (formerly ME-1206) is an investigational, orally administered cephalosporin ester with bactericidal activity against many Gram-positive and -negative organisms. Cefditoren potency against nearly 1000 non-fastidious species was determined by National Committee for Clinical Laboratory Standards (NCCLS) reference broth microdilution and standardized disk diffusion methods. Against staphylococci, usable cefditoren activity was completely correlated with oxacillin with respect to potency and susceptibility interpretation (mec A-negative strains). Cefditoren was very active against Klebsiella spp., Proteus mirabilis, Salmonella spp., and Escherichia coli (MIC(90) range, 0.12-1 microg/ml; median zone, 23-26 mm). Cefditoren had more limited activity against Citrobacter spp., Enterobacter spp., Serratia marcescens, and indole-positive Proteae (MIC(50) range, 0.12-1 microg/ml; MIC(90), > 16 microg/ml; median zone, 18-25 mm). Against Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Acinetobacter spp., and other non-fermentors, cefditoren was inactive (MIC(90), > 16 microg/ml; zone, 6 mm). Pharmacokinetic analysis of cefditoren showed that utilized dosages produce a plasma concentration that exceeds 0.5 microg/ml for 5 to 8 h and 1 microg/ml for 4 to 6 hours (T(1/2) ranges from 1.5-2 h). The following interpretive criteria were suggested: </= 2 microg/ml or >/= 15 mm (susceptible) and >/= 8 microg/ml or </= 11 mm (resistance) that yielded an intermethod categorical agreement of 95.8% and very major or major error rates of 0.7% and 0.3%, respectively. Alternatively, </= 1 microg/ml or >/= 18 mm (susceptible) and >/= 4 microg/ml or </= 14 mm (resistant) breakpoints resulted in 96.2% accuracy and combined serious errors of only 1.1%. Cefditoren was observed to be a very active cephalosporin ranking among the most potent available orally active beta-lactams for use against a wide variety of pathogens.

Cephalosporins↗
PubMed2000

Antimicrobial activity and in vitro susceptibility test development for cefditoren against Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus species.

Cefditoren, a third generation orally administered aminothiazolyl cephalosporin, has demonstrated bactericidal activity against many Gram positive and negative bacterial pathogens and stability against clinically important beta-lactamases. Cefditoren was compared to cefaclor, cefixime, and penicillins against 1 435 recently isolated strains of streptococci (312 Streptococcus pneumoniae, 165 viridans group streptococci, 142 beta-haemolytic streptococci), Haemophilus influenzae (521 strains), and Moraxella catarrhalis (295 strains). Streptococcus pneumoniae and viridans group streptococci had penicillin nonsusceptible rates of 37.8 and 35.8%, respectively. Cefditoren (MIC(90) in microg/ml/% susceptible) activity against all tested H. influenzae (0.03/100) and M. catarrhalis (0.06-0.5/100) was comparable to cefixime and significantly greater than cefaclor. Cefditoren (MIC(90), 0.5 microg/ml) was 4- to 128-fold more active than comparison beta-lactams against the pneumoococci and was the most potent beta-lactam (including penicillin) versus beta-haemolytic streptococci. Cefditoren pharmacokinetics demonstrate a T(1/2) of 1.5-2 h and C(max) values of 2.8 and 4.6 microg/ml, respectively with 200 or 400 mg doses of cefditoren pivoxil; plasma concentrations exceed 1 microg/ml for 4 to 6 hours (33-50% of dosing interval). Consequently, a susceptible MIC of </= 1 microg/ml or </= 2 microg/ml was proposed with zone diameter correlates of >/= 18 and >/= 15 mm (5-microg disk) for all cited fastidious species tested. Categorical agreement between MIC and disk tests was 94.6 to 100% with a correlation coefficient (r) range of 0.50 to 0.90 for streptococci. H. influenzae intermethod comparison results using the same interpretive criteria were in complete agreement, but exhibited a low r = 0.39. Cefditoren clearly possesses the most potent activity among currently studied oral cephalosporins or penicillin against commonly isolated bacterial pathogens causing bronchitis, pneumonia, sinusitis, or pharyngitis and was active against nearly all penicillin-resistant streptococci at </= 0.5 microg/ml. Expanded clinical investigations seem warranted.

Cefaclor↗
PubMed2000

Development of gemifloxacin in vitro susceptibility test methods for gonococci including quality control guidelines. The Quality Control Study Group.

Gemifloxacin (formerly SB-265805 or LB20304a) is a new fluoronapthyridone with documented activity against Gram-positive and -negative organisms. The activity of gemifloxacin was tested against 150 Neisseria gonorrhoeae strains, using reference agar dilution, standardized disk diffusion, and Etest (AB BIODISK, Solna, Sweden) methods. Gemifloxacin was very potent against ciprofloxacin (CIPRO)-susceptible strains (MIC(90,) 0.008 microg/ml) but was significantly less active against the CIPRO-resistant gonococci (MIC(90,) 0.12 microg/ml). Etest and reference agar dilution MIC results showed excellent correlation (r = 0.96), and 98.7% MICs were within +/- one log(2) dilution. Agar dilution MICs were also compared to zone diameters obtained using gemifloxacin 5-microg disks; and complete intermethod categorical agreement (100%) was achieved applying breakpoints proposed as follows: < or =0.25 microg/ml (zone, > or =25 mm) for susceptible and > or =1 microg/ml (zone, < or =21 mm) for resistant. Gemifloxacin MIC and disk diffusion te quality control (QC) ranges were established for N. gonorrhoeae ATCC 49226. Data were collected from > or = seven laboratories, three GC agar medium lots for both agar MICs and disk methods, and two lots each of the 5- and 10-microg disks. The proposed MIC QC range was 0.002 to 0.016 microg/ml and the calculated mm zone ranges (median +/- 0.5x average mm range) for both disks were similar, but contained only 88.1 to 91.9% of participant results. To achieve the acceptable > or = 95% of all study results within range, a 43 to 54 mm limits (5-microg disks) were necessary. The excellent broad-spectrum activity and a low reported adverse effects profile of gemifloxacin shows a potential for treatment of fluoroquinolone-resistant gonorrhea.

Anti-Infective Agents↗
PubMed2000

Antimicrobial activity and spectrum of the new glycylcycline, GAR-936 tested against 1,203 recent clinical bacterial isolates.

The in vitro activity of GAR-936, a new semisynthetic glycylcycline, was evaluated in comparison with two tetracyclines and several other antimicrobial agents. A total of 1,203 recent clinical isolates were tested by reference broth or agar dilution methods. Among the members of the family Enterobacteriaceae, GAR-936 was generally two- to four-fold more active than minocycline, and two- to 16-fold more active than tetracycline. All enteric bacilli MIC90 results were < or = 4 microg/mL; the exception being Proteus mirabilis and indole-positive Proteae (> or = 8 microg/mL). GAR-936 demonstrated excellent activity against all gram-positive cocci with 90% of the penicillin-resistant Streptococcus pneumoniae isolates inhibited at 0.03 microg/ml, while the same isolates had a MIC90 of 8 and > 8 microg/mL for minocycline and tetracycline, respectively. All Enterococcus spp., including vancomycin-resistant isolates, were inhibited at 0.25 microg/mL of GAR-936 (MIC90, 0.12 or 0.25 microg/mL). Although GAR-936 (MIC50, 0.25 microg/mL) was two-fold less active than minocycline (MIC50, 0.12 microg/mL) against oxacillin-resistant Staphylococcus aureus, all isolates were inhibited at < or = 0.25 microg/mL. GAR-936 demonstrated good activity against nonfermentative bacteria such as Acinetobacter spp. (MIC90, 2 microg/ml) and Stenotrophomonas maltophilia (MIC90, 4 microg/mL), but the compound exhibited only modest activity against Pseudomonas aeruginosa (MIC50, 8 microg/mL). Haemophilus influenzae (MIC90, 1-2 microg/mL), Moraxella catarrhalis (MIC90, 0.12 microg/mL), and various Neisseria spp. (MIC90, 0.12-0.5 microg/mL) were susceptible to GAR-936. These results indicate that GAR-936 has potent in vitro activity against a wide range of clinically important pathogenic bacteria, and that several gram-positive and -negative isolates resistant to older tetracyclines and other drug classes remain susceptible to GAR-936, the newest glycylcycline candidate for clinical use.

Anti-Bacterial Agents↗
PubMed2000

Comparison of the activity of two broad-spectrum cephalosporins tested against 2,299 strains of Pseudomonas aeruginosa isolated at 38 North American medical centers participating in the SENTRY Antimicrobial Surveillance Program, 1997-1998.

Pseudomonas aeruginosa is an important nosocomial pathogen. Resistance to certain beta-lactam antimicrobial agents among P. aeruginosa is increasing. The SENTRY Antimicrobial Surveillance Program was designed to employ a network of hospitals in the United States, Canada, Latin America, and Europe to monitor the predominant bacterial and fungal pathogens and antimicrobial susceptibility patterns associated with community-acquired and nosocomial bloodstream, respiratory tract, wound, and urinary tract infections. The purpose of this analysis of SENTRY results was to extract information on the current North American susceptibility pattern of P. aeruginosa for two antipseudomonal cephalosporins, ceftazidime, and cefepime. Clinical isolates were provided by 30 centers in the United States (grouped into five regions) and eight centers in Canada. Susceptibility testing was performed at a central reference laboratory by using broth microdilution methods and interpretive criteria specified by the National Committee for Clinical Laboratory Standards. Of the 34, 530 North American bacterial isolates tested during 1997 and 1998, 2299 (6.7%) were P. aeruginosa. There were no substantial differences in regional rates of P. aeruginosa susceptibility to ceftazidime (range 78.8-81.9%) or cefepime (range 80.0-83.4%) The percentage of resistant isolates among the 1784 United States isolates was 13.3% for ceftazidime versus 7.1% for cefepime (p < 0.05). It is essential to continue surveillance of the in vitro efficacy of these and other beta-lactam agents against P. aeruginosa because of the clinical importance of these safe and broad-spectrum cephems used alone or in combination in current clinical practice.

Cefepime↗
PubMed2000

Occurrence of single-point gyrA mutations among ciprofloxacin-susceptible Escherichia coli isolates causing urinary tract infections in Latin America.

To detect if isolates susceptible to quinolones already carry mutations in the gyrA and parC genes, we selected 12 ciprofloxacin-susceptible Escherichia coli strains collected from patients with urinary tract infections in Latin America in 1998, as part of ongoing SENTRY Antimicrobial Surveillance Program. The isolates studied exhibited minimal inhibitory concentrations (MICs) for ciprofloxacin between < or = 0.015 microg/mL and 0.5 microg/mL. The molecular characterization of quinolone resistance was determinated by amplification of the gyrA and parC by PCR followed by sequencing of the respective amplicons. We observed that E. coli isolates exhibiting MIC, < or = 0.06 microg/mL for ciprofloxacin did not show mutations in either topoisomerase. On the other hand, all isolates with MIC between 0.12 microg/mL and 0.5 microg/mL demonstrated single mutation in the gyrA gene. The most frequent mutation occurred at position 83, where the amino acid serine was replaced by leucine. No mutations in the parC gene were observed. To preserve the potency and prevent the development of resistance, we suggest that quinolone usage should be rational, especially in the treatment of urinary tract infections, and in the prophylaxis of immunosupressed patient populations.

Anti-Infective Agents↗
PubMed2000

A nationwide, multicenter, case-control study comparing risk factors, treatment, and outcome for vancomycin-resistant and -susceptible enterococcal bacteremia.

National Nosocomial Resistance Surveillance Group participants from 22 hospitals across the United States reviewed medical records for hospitalized patients with vancomycin-resistant enterococcal (VRE) or vancomycin-susceptible enterococcal (VSE) bacteremia to identify risk factors associated with the acquisition of VRE bacteremia, describe genetic traits of VRE strains, and identify factors predictive of clinical outcome. VRE cases were matched to VSE controls within each institution. Multiple logistic regression (LR) and classification and regression tree (CART) analysis were used to probe for factors associated with VRE bacteremia and clinical outcome. A total of 150 matched-pairs of VRE cases and VSE controls were collected from 1995 to 1997. Using LR, the following were found to be highly associated with VRE bacteremia: history of AIDS, positive HIV status, or drug abuse (OR 9.58); prior exposure with parenteral vancomycin (OR 8.37); and liver transplant history (OR 6. 75). CART analysis revealed that isolation of Enterococcus faecium, prior vancomycin exposure, and serum creatinine values > or = 1.1 mg/dl were predictors of VRE bacteremia. Greater proportions of clinical failure (60% versus 40%, P < 0.001) and all-cause mortality (52% versus 27%, P < 0.001) were seen in patients with VRE versus VSE bacteremia. Results from both LR and CART indicated that patients with persisting enterococcal bacteremia, intubation at baseline, higher APACHE II scores, and VRE bacteremia were at greater risk for poor outcome.

APACHE↗
PubMed2000

In vitro efficacy of six cephalosporins tested against Enterobacteriaceae isolated at 38 North American medical centres participating in the SENTRY Antimicrobial Surveillance Program, 1997-1998.

The SENTRY Antimicrobial Surveillance Program is an ongoing international collaboration that monitors the predominant bacterial and fungal pathogens and antimicrobial susceptibility patterns associated with community-acquired and nosocomial infections. SENTRY data on the current cephalosporin susceptibility patterns (1997-98) of North American isolates of clinically important Enterobacteriaceae were analyzed. Susceptibility to a selection of cephalosporins was assessed at a central laboratory using reference broth microdilution methods and interpretive criteria specified by the National Committee for Clinical Laboratory Standards. The third- and fourth-generation cephalosporins tested demonstrated excellent activity against Escherichia coli and Klebsiella pneumoniae, whereas some of the older agents maintained good efficacy. Extended spectrum beta-lactamases were detected in all regions of the United States and Canada (1.8-10.7%). Cefepime was the most active agent tested against pathogens with the potential for enzyme-mediated resistance due to Amp C. The third-generation agents maintained acceptable efficacy against Serratia marcescens, but were less effective against Citrobacter and Enterobacter species. The older cephalosporins were generally inadequate against these pathogens, in contrast to cefepime, which was the widest spectrum cephalosporin overall. Some significant regional variations in spectrum were detected.

Cefepime↗
PubMed2000

Evaluation of gemifloxacin (SB-265805, LB20304a): in vitro activity against over 6000 gram-positive pathogens from diverse geographic areas.

Gemifloxacin (GEMI), formerly SB-265805 and LB20304, is a newer fluoroquinolone with broad-spectrum activity against a wide variety of bacterial pathogens. The present investigation extended earlier observations by sampling an additional 6790 gram-positive organisms from more than 50 medical centres on three continents. The reference broth microdilution method with recommended medium supplements was used throughout. Selected results (number strains tested; MIC90 for GEMI/trovafloxacin in mg/l; % < or = 1 mg/l for GEMI/trovafloxacin) were: Staphylococcus aureus (3672; 2/2; 86/85), S. epidermidis (404; 1/>4; 92/71), Enterococcus faecalis (630; 4/>4; 76/66), E. faecium (216; > 4/>4; 15/11), Streptococcus pneumoniae (300; 0.06/0.25; 100/97), beta-haemolytic streptococci (150; 0.06/0.25; 100/100) and viridans group streptococci (150; 0.12/0.25; 99/97). Gemifloxacin appeared equal or superior to trovafloxacin in its overall gram-positive spectrum of activity pending a choice of the susceptible breakpoint concentration. Continued in vitro, pharmacodynamic and clinical investigations of gemifloxacin appear warranted.

Anti-Infective Agents↗
PubMed2000

Evaluation of quinupristin/dalfopristin (Synercid) and RPR 106972 stability in susceptibility testing media.

In response to conflicting reports on the chemical stability of quinupristin/dalfopristin, a study was designed to assess the in vitro longevity and effects of media and storage conditions on this streptogramin combination. Broth microdilution trays containing parenteral (quinupristin/dalfopristin) and oral (RPR 106972) streptogramin combinations as well as pristinomycin components (P-I and P-II) were preincubated at 35 degrees C for 12-72 h before inoculation with control strains (Streptococcus pneumoniae ATCC 49619, Haemophilus influenzae ATCC 49247, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 29213) and five clinical isolates with various drug resistance phenotypes. Overall, the mean quinupristin/dalfopristin activity loss was 24%/12 h, 41%/18 h, 43%/24 h, 69%/48 h and 79%/72 h with no detected loss of potency when measured by E. faecalis until 18 h. RPR 106972 mean activity loss was 6%/12 h, 19%/18 h, 19%/24 h, 56%/48 h and 71%/72 h with no loss of potency as measured by S. aureus until 48 h. Overall, P-I components had greater stability as compared with P-II for both drug combinations. Bioassays showed similar trends in decreased activity. Bioassay differences among media types were only significant (> 3 mm; greater loss of potency) for haemophilus test media for both P-II components at 72 h. The presence of an organism in the medium had no effect on stability assay results. The effect of storage temperature (4, 25 degrees C) on quinupristin/dalfopristin and RPR 106972 stability was also detrimental to drug potency indicating the requirement for rigid quality assurance for streptogramin diagnostic reagents when determining activity by reference or standardized susceptibility tests.

Anti-Bacterial Agents↗
PubMed2000

In vitro activity of ceftiofur tested against clinical isolates of Escherichia coli and Klebsiella pneumoniae including extended spectrum beta-lactamase producing strains.

In vitro activity of ceftiofur, a cephalosporin used in veterinary practice was compared using ceftriaxone-resistant (producing extended spectrum beta-lactamase (ESBL)) and -susceptible clinical isolates of Esherichia coli and Klebsiella pneumoniae. The ceftriaxone-susceptible isolates exhibited a lower range of ceftiofur MICs (MIC50, 0.5 mg/l, MIC90 1.0 mg/l). Those isolates known to produce an ESBL were also resistant to ceftiofur (MIC50, > or = 32 mg/l). The latter isolates were also less susceptible to other comparator drugs (cefquinome, gentamicin and trimethoprim/sulphamethoxazole) in contrast to the ceftriaxone-susceptible strains. The clinical isolates showed high correlation between ceftriaxone and ceftiofur MICs (y = 2.6 + 0.89x, r = 0.95). Using the current ceftiofur susceptible breakpoint (< or = 2 mg/l) used for veterinary practice (respiratory tract pathogens), the ESBL-producing strains of E. coli and K. pneumoniae could be accurately separated from susceptible strains. This ceftiofur breakpoint MIC corresponds to the National Committee for Clinical Laboratory Standards ESBL screening concentration for ceftriaxone set at < or = 1 mg/l = negative for ESBL production. Ceftiofur was also observed to be very active in vitro against ampicillin-resistant, non-ESBL producing enteric isolates. This new cephem appears to be very potent against the tested Enterobacteriaceae and of potential wide clinical veterinary utility.

Animals↗
PubMed2000

Trends in antimicrobial susceptibility of bacterial pathogens isolated from patients with bloodstream infections in the USA, Canada and Latin America. SENTRY Participants Group.

From January through June of 1998, 4579 bloodstream infections (BSI) due to bacterial pathogens were reported from SENTRY hospitals in Canada, the USA and Latin America. Staphylococcus aureus, Escherichia coli, and coagulase-negative staphylococcus (CoNS) were the most common pathogens, together accounting for 55.2% of all BSI during this time period. Compared with the 5794 BSI reported from SENTRY from January through June of 1997, no major change was seen in the frequencies of occurrence of the most common bacterial causes of BSI. Between 1997 and 1998, the major change in antimicrobial resistance was an increase in oxacillin-resistance in both S. aureus and CoNS in all regions. These data demonstrate widespread antimicrobial resistance in Canada, Latin America and the USA, with a notable increase in oxacillin-resistance among staphylococci. Ongoing surveillance remains essential, and will enhance efforts to limit the scope of this worldwide problem.

Bacteremia↗
PubMed2000

Two-year assessment of the pathogen frequency and antimicrobial resistance patterns among organisms isolated from skin and soft tissue infections in Latin American hospitals: results from the SENTRY antimicrobial surveillance program, 1997-98. SENTRY Study Group.

OBJECTIVES: This study was conducted to evaluate the frequency of occurrence and antimicrobial susceptibility of bacterial isolates collected from patients with skin and soft tissue infections (SSTI) in Latin American hospitals, as part of the SENTRY Antimicrobial Surveillance Program. The dissemination of multidrug-resistant methicillin-resistant Staphylococcus aureus (MDR-MRSA) among the Latin American countries also was studied. MATERIAL AND METHODS: A total of 885 bacterial isolates were analyzed. At the monitoring laboratory, antimicrobial susceptibility testing utilizing the reference broth microdilution method and confirmation of species identification were performed. Enterobacteriaceae possibly producing extended-spectrum beta-lactamases (ESBL) and MDR-MRSA isolates were genotyped by ribotyping using the RiboPrinter and by pulsed-field gel electrophoresis. RESULTS: Staphylococcus aureus (31%) was the most common etiologic agent causing SSTI, followed by Escherichia coli (13.4%) and Pseudomonas aeruginosa (11%). Thirty-one percent of S. aureus isolates were resistant to oxacillin (methicillin). The presence of ESBL phenotypes was markedly higher among the Klebsiella pneumoniae (35.5%) than E. coli isolates (10. 2%). Meropenem was the compound with the highest susceptibility rate among the Enterobacteriaceae (100%) and P. aeruginosa (95%) isolates. A great genetic similarity was observed among the MDR-MRSA in Latin America. CONCLUSION: High resistance rates to antimicrobial drugs among the most frequent bacterial pathogens were observed in 10 medical centers in Latin America. This study also demonstrated a clonal dissemination of a MDR-MRSA strain in several nations.

Anti-Bacterial Agents↗
PubMed2000

Dimensions of the Mini-Mental State Examination among community dwelling older adults.

BACKGROUND: Little work has been published on the internal structure of the Mini-Mental State Examination (MMSE), one of the most widely used instruments for grading cognitive status in clinical settings and field research. METHODS: MMSE responses from a sample of older adults (50-98 years) in five US sites (N = 8556) were analysed. RESULTS: A five-factor solution was found to be most appropriate. The first factor (concentration) had large loadings with serial sevens and spell world backwards items. The second factor (language and praxis) had large loadings with naming, follow command and praxis items. The third factor (orientation) had loadings with orientation to time and place items. The fourth factor (memory) had large loadings with delayed recall items and the fifth (attention) had large loadings with immediate registration items. CONCLUSIONS: We found that the MMSE is essentially unidimensional; nevertheless, evidence was revealed suggesting that the MMSE is a multidimensional assessment instrument. Dimensions revealed in this sample correspond directly to MMSE sections articulated by the developers of the instrument. These findings have not been reported in previous factor analyses of the MMSE. The findings support the construct validity of the MMSE as a measure of cognitive mental state among community dwelling older adults.

Aged↗
PubMed2000

Modification of wheat rDNA loci by rye B chromosomes: a chromatin organization model.

The rDNA loci, and their associated NORs, on chromosomes 1B and 6B of the hexaploid wheat cv. Lindström have been used as a chromatin marker to investigate the functional basis of the phenotype effects of introgressed supernumerary B chromosomes (Bs) of rye. The rye Bs themselves lack genes, other than those which determine their mitotic drive mechanism, and the way in which they can modulate characters determined by the A chromosome background has always been a puzzle. An isogenic line of Lindström plants carrying different numbers of Bs was used as the experimental system to see how different doses of Bs (from 0 to 6) affected the activity of the wheat NORs and the organization of their rDNA loci at interphase. Silver staining on metaphase chromosomes was used to evaluate the previous activity of the NORs, and to reveal variations in their size; and the pTa71 FISH probe from wheat was used to visualize structural modifications to the interphase rDNA loci. A single B had no measurable effect, but, as the B-number increased, there were significant changes in the physical dimensions of the metaphase NORs, reflecting reduced levels of their activity earlier in the cell cycle, and also in the condensation patterns of the interphase rDNA loci. In addition, the higher B-numbers caused a size heteromorphism between the homologous NORs. A model is discussed which interprets the phenotypic effects of Bs generically, in nucleotypic terms, based of their being 'genetically inert' but 'chromosomally active'.

Chromatin↗
PubMed2000

Pharyngeal colonization prevalence rates for Streptococcus pyogenes and Streptococcus pneumoniae in a respiratory chemoprophylaxis intervention study using azithromycin.

OBJECTIVES: A prospective assessment of the pharyngeal colonization prevalence rates for Streptococcus pyogenes and Streptococcus pneumoniae before and after an azithromycin chemoprophylaxis intervention clinical trial in a cohort of US Marine Corps trainees. In addition, the minimum inhibitory concentrations (MICs) for all streptococcal isolates, for azithromycin, penicillin, erythromycin and cefotaxime are reported. METHODS: Between November 1994 and March 1995, 1108 asymptomatic male US Marine Corps trainees, located in Southern California, were randomly assigned to one of three intervention groups: (1) weekly oral azithromycin, 500 mg (n = 362); (2) 1.2 MU benzathine penicillin G, intramuscularly once (n = 374); or (3) no chemoprophylaxis (n = 372). Subjects provided both a pre- and post-training pharyngeal culture and microbial analysis was conducted to determine the colonization status of each study subject. RESULTS: The pretraining colonization prevalence was 1.2% for S. pneumoniae and 2.4% for S. pyogenes. There was no statistical difference in pretraining prevalence between the three treatment groups for either organism. Post-training pharyngeal cultures revealed an overall prevalence of 1.1% with no difference between treatment arms. However, the overall post-training prevalence of S. pyogenes colonization increased to 4.8%, with the azithromycin group having significant evidence of protection (0.7%) in comparison with the no-treatment group (8.2%). The Etest method demonstrated no significant difference in the MIC50, MIC90, and MIC ranges between pre- and post-training isolates for any of the tested drugs. CONCLUSION: The use of azithromycin as a chemoprophylactic agent to reduce the colonization and subsequent infection of streptococcal respiratory disease among healthy adult male military recruits may be beneficial.

Anti-Bacterial Agents↗
PubMed2000

Group B streptococci causing neonatal bloodstream infection: antimicrobial susceptibility and serotyping results from SENTRY centers in the Western Hemisphere.

OBJECTIVE: Group B streptococcal infection is a common cause of neonatal sepsis. Surveillance of antimicrobial susceptibility and serotype frequencies of invasive group B streptococci is important to ensure the effectiveness of therapeutic regimens and to guide vaccine development. STUDY DESIGN: Prospective surveillance of neonatal bloodstream infection was performed at all Western Hemisphere sites participating in the SENTRY Program. From January 1997 through December 1999, a total of 122 isolates of bloodstream infections with group B streptococci were collected and sent to the University of Iowa for antimicrobial susceptibility testing and serotyping. RESULTS: No isolates were resistant to penicillin. More than 25% of isolates from US hospitals and 14% of isolates from Canadian hospitals were erythromycin resistant. Seven percent of isolates from the United States and Canada were resistant to clindamycin. No clindamycin or erythromycin resistance was found among isolates from Latin America. Clindamycin and erythromycin resistance was most frequent among serotype V strains. CONCLUSIONS: No emerging resistance to penicillin was noted among bloodstream infection isolates of group B streptococci from a broad geographic area; erythromycin and clindamycin resistance was found in the United States and Canada and appeared most frequently among serotype V strains.

Anti-Bacterial Agents↗