Showing papers on "Penicillin published in 1997"

Resistance to Glycopeptides in Enterococci

Abstract: The development of resistance to glycopeptides (vancomycin and teicoplanin) is one of the best examples of the alternation between success and failure that spans the history of the antibiotic era. The introduction of penicillin G was revolutionary. However, the emergence in the 1950s of clinical isolates of Staphylococcus aureus that were resistant to penicillins and subsequently to erythromycin and tetracyclines stimulated the development of large-scale screening programs for new drugs. Under these circumstances, an American missionary, Reverend W. M. Bouw, provided Eli Lilly (Indianapolis) with a soil sample from Borneo [1]. The organism that produces vancomycin, Amycolatopsis orientalis, was isolated from this sample in 1954. Since vancomycin proved to be potent against grampositive bacteria, including penicillinase-producing staphylococci, it was licensed for human use in record time. However, the renal toxicity and ototoxicity associated with vancomycin therapy (due for the most part to impurities in the drug) together with the introduction of new penicillinase-resistant /-lactams led to a rapid decline in the use of vancomycin. In the 1980s, interest in vancomycin revived because of several factors. During this period, methicillin-resistant and multiresistant staphylococci, against which vancomycin is often the only active antibiotic, were emerging worldwide. At the same time, medical advances had resulted in the prolongation of life for increasingly fragile, immunocompromised patients who are exposed to opportunistic pathogens such as multiresistant gram-positive organisms. In addition, it was determined that pseudomembranous colitis could be treated with oral vancomycin, and a new glycopeptide, teicoplanin, was introduced in 1984 in certain European countries. The apparent absence of resistance to vancomycin in grampositive bacteria and a decrease in the toxicity associated with vancomycin therapy (purified formulations of the drug had become available) led to a notable increase in the prescription of this antibiotic. In the United States, a 20-fold increase in the consumption of vancomycin was observed over a 10-year period at a university hospital [2].

Gram-positive resistance: challenge for the development of new antibiotics.

Abstract: The incidence of infections caused by multidrug-resistant Gram-positive organisms is increasing despite advances in antibacterial therapy over the last 20 years. As the pathogens causing these infections are frequently resistant to most currently available antibacterials, they are extremely difficult to treat. Problematic pathogens include strains of Streptococcus pneumoniae resistant to beta-lactams and macrolides, viridans group streptococci resistant to beta-lactams and aminoglycosides, enterococci resistant to vancomycin and teicoplanin and highly resistant to penicillins and aminoglycosides, and Staphylococcus aureus resistant to methicillin, other beta-lactams, macrolides, lincosamides and aminoglycosides. Other important pathogens include Streptococcus pyogenes resistant to macrolides (and suspected to be resistant to penicillin), macrolide-resistant streptococci of groups B, C, and G, coagulase-negative staphylococci resistant to beta-lactams, aminoglycosides, macrolides, lincosamides and glycopeptides, multiresistant strains of Listeria and Corynebacterium and Gram-positive anaerobes, such as Peptostreptococcus and Clostridium, resistant to penicillins and macrolides. Thus, there is an urgent need for new antibacterial agents that are able to overcome multidrug-resistant mechanisms. The novel semisynthetic injectable streptogramin quinupristin/dalfopristin offers the prospect of effective treatment against many of the above pathogens.

Mechanisms of bacterial resistance to antimicrobial agents.

Abstract: The mechanisms behind the development and spread of bacterial resistance to antimicrobial drugs are reviewed. The chief mechanisms by which antimicrobials act are interference with nucleic acid synthesis, binding to ribosomes, and inhibition of cell-wall synthesis and folate metabolism. Bacteria have evolved genetic and biochemical ways of resisting these antimicrobial actions. Genetic mechanisms include mutation and acquisition of new DNA. Bacteria resist antimicrobials biochemically by inactivating the drugs with beta-lactamases, acetylases, adenylases, and phosphorylases; reducing drug access sites of action by virtue of membrane characteristics; altering the drug target so that the antimicrobial no longer binds to it; bypassing the drug's metabolism; and developing tolerance. Enterococcal and staphylococcal resistance mechanisms are of particular importance clinically. There are three types of enterococcal resistance: (1) intrinsic resistance to aminoglycosides, aztreonam, cephalosporins, clindamycin, imipenem, penicillin, and trimethoprim-sulfamethoxazole, (2) tolerance to all cell-wall-active antimicrobials, and (3) acquired resistance to penicillin, aminoglycosides, chloramphenicol, erythromycin, tetracycline, and vancomycin. Staphylococcal resistance to penicillins is expressed as beta-lactamase production, secretion of novel beta-lactamases, expression of novel penicillin-binding proteins (PBPs) to which penicillins bind poorly, and increased production of or altered affinity to existing PBPs. Of great concern is whether newly described glycopeptide resistance can be transferred clinically from enterococci to staphylococci. Vancomycin use is discouraged to limit the spread of glycopeptide resistance. Many mechanisms are responsible for the development and spread of antimicrobial resistance.

Resistant pneumococci: protecting patients through judicious use of antibiotics.

Abstract: Increasing resistance to antimicrobial agents has occurred among many pathogens, but the emergence of resistant Streptococcus pneumoniae will have the greatest impact on the practice of outpatient medicine. Consequences of resistance include complicated management of acute otitis media and meningitis treatment failures. Pneumococci have acquired resistance to penicillin, third-generation cephalosporins and other antibiotics at an alarming rate; in some areas, 25 percent of isolates are nonsusceptible to penicillin. In areas with high resistance rates, the addition of vancomycin to cefotaxime or ceftriaxone is warranted for empiric treatment of bacterial meningitis. Changes in empiric therapy for pneumonia, bacteremia and otitis media may eventually be necessary. Previous antibiotic use is a risk factor for invasive disease with resistant pneumococci. Patients may be best protected by avoiding unnecessary use of antibiotics. Patient education materials as well as recommendations for avoiding the use of antibiotics for some upper respiratory tract infections are currently being developed to help physicians achieve this goal.

Multivariate Analysis of Risk Factors for Infection Due to Penicillin-Resistant and Multidrug-Resistant Streptococcus pneumoniae: A Multicenter Study

Abstract: Pneumococcal disease was studied prospectively to determine the risk factors associated with resistance to penicillin and other antibiotics. One hundred twelve clinically significant pneumococcal isolates were recovered from 95 patients. Approximately one-half (49.47%) of the cases were due to penicillin-resistant strains. Multivariate analysis showed that previous use of beta-lactam antibiotics (odds ratio [OR], 2.81; 95% confidence interval [CI], 0.95-8.27), alcoholism (OR, 5.22; 95% CI, 1.43-19.01), and noninvasive disease (OR, 4.53; 95% CI, 1.54-13.34) were associated with penicillin resistance, whereas intravenous drug use (OR, 0.14; 95% CI, 0.03-0.74) was not. Statistical analyses of the variables associated with resistance to multiple antibiotics detected age of younger than 5 years (OR, 16.79; 95% CI, 1.60-176.34) or of 65 years or older (OR, 4.33; 95% CI, 1.42-13.21) and previous use of beta-lactam antibiotics by patients with noninvasive disease (OR, 7.92; 95% CI, 1.84-34.06) as parameters associated with increased risk. We conclude that multivariate analysis provides clues for empirical therapy for pneumococcal infection.

Increased production of penicillin-binding protein 2, increased detection of other penicillin-binding proteins, and decreased coagulase activity associated with glycopeptide resistance in Staphylococcus aureus.

Abstract: The mechanism of glycopeptide resistance in the genus Staphylococcus is unknown. Since these antimicrobial compounds act by binding the peptidoglycan precursor terminus, the target of transglycosylase and transpeptidase enzymes, it was hypothesized that resistance might be mediated in Staphylococcus aureus by increased production or activity of these enzymes, commonly called penicillin-binding proteins (PBPs). To evaluate this possibility, glycopeptide-resistant mutants were prepared by passage of several clinical isolates of this species in nutrient broth containing successively increasing concentrations of the glycopeptide vancomycin or teicoplanin. Decreased coagulase activity and increased resistance to lysostaphin were uniformly present in the vancomycin-resistant mutants. Peptidoglycan cross-linking increased in one resistant isolate and decreased in two resistant isolates. The amounts of radioactive penicillin that bound to each PBP in susceptible and resistant strains were compared; PBP2 production was also evaluated by Western blotting. Increased penicillin labeling and production of PBP2 were found in all resistant derivatives selected by either vancomycin or teicoplanin. Moreover, the increase in PBP2 penicillin labeling occurred early in a series of vancomycin-selected derivatives and was strongly correlated (r > 0.9) with the increase in vancomycin and teicoplanin MIC. An increase in penicillin labeling also occurred, variably, in PBP1, PBP3, and/or PBP4. These data demonstrate a strong correlation between resistance to glycopeptides and increased PBP activity and/or production in S. aureus. Such an increase could allow PBPs to better compete with glycopeptides for the peptidoglycan precursor.

Enterococci Acquire New Kinds of Resistance

Abstract: In recent years, enterococci have become increasingly resistant to a broad range of antimicrobial agents. The development of high-level resistance to aminoglycosides, penicillins, and glycopeptides singly and in combination has important clinical implications. Strains of Enterococcus faecium that are resistant to every useful available antibiotic have been described. Resistance to penicillin can be due to overproduction of penicillin-binding protein (which has low affinity for penicillins) or to production of beta-lactamase. High-level resistance of enterococci to gentamicin is due to the synthesis of a modifying enzyme. In this case, the synergistic activity of the combination of penicillin with any aminoglycoside (except for streptomycin) is totally abolished. Acquired resistance to glycopeptides is often plasmid-mediated and is associated with a major epidemic potential since certain plasmids are self-transferable from E. faecium to a variety of gram-positive organisms, including Staphylococcus aureus.

A global gene pool for high-level cephalosporin resistance in commensal Streptococcus species and Streptococcus pneumoniae

Abstract: Highly penicillin- and cephalosporin-resistant Streptococcus mitis and Streptococcus oralis were isolated in Spain, Hungary, and Berlin. With chromosomal DNA of these strains, resistant transformants of Streptococcus pneumoniae were obtained that expressed low-affinity variants of penicillin-binding proteins (PBPs) 2x, 1a, 2a, and 2b in different combinations, depending on the selective conditions. The transformants had cefotaxime MICs of up to 6 microg/mL, and those with a low-affinity PBP 2b were highly deficient in penicillin-induced lysis. Sequence analysis of the pbp2x genes confirmed the presence of a global gene pool of penicillin resistance determinants shared by commensal and pathogenic streptococci.

Antimicrobial Resistance in Neisseria gonorrhoeae in the United States, 1988–1994: The Emergence of Decreased Susceptibility to the Fluoroquinolones

Abstract: Antimicrobial susceptibilities of Neisseria gonorrhoeae have been prospectively determined in the Gonococcal Isolate Surveillance Project of the Centers for Disease Control and Prevention. From 1988 through 1994, susceptibilities were determined for 35,263 isolates from 27 clinics. Patients were demographically similar to those in nationally reported gonorrhea cases. In 1994, 30.5% of isolates had chromosomally or plasmid-mediated resistance to penicillin or tetracycline. Penicillin resistance increased from 1988 (8.4%) to 1991 (19.5%) and then decreased in 1994 (15.6%). Tetracycline resistance decreased from 1988 (23.4%) to 1989 (17.3%) and then increased in 1994 (21.7%). Most isolates (99.9%) were highly susceptible to broad-spectrum cephalosporins. Isolates with decreased susceptibility to ciprofloxacin increased from 1991 (0.4%) to 1994 (1.3%); 4 isolates were ciprofloxacin-resistant. Ciprofloxacin-resistant strains may not respond to therapy with recommended doses of fluoroquinolones, and the clinical importance of strains with decreased susceptibility is unknown. The emergence of fluoroquinolone resistance in N. gonorrhoeae in the United States threatens the future utility of this class of antimicrobials for gonorrhea therapy.

Analysis of a commercially improved Penicillium chrysogenum strain series: involvement of recombinogenic regions in amplification and deletion of the penicillin biosynthesis gene cluster

Abstract: Several commercially improved strains of Penicillium chrysogenum have been shown to carry amplifications of the entire penicillin biosynthesis gene cluster. Analysis previously carried out using the strain BW 1890 has here been extended to the characterisation of other members of the SmithKline Beecham strain improvement series. We have determined the length of the amplicon to be 57.4 kb and shown a general increase in copy number and penicillin titre through the series. Sequence analyses of the promoter regions of the acvA, ipnA and aat genes in the high titre strain BW 1901, and comparisons with wild-type sequences have not identified any potentially titre-enhancing mutations. In addition, cDNA screening has failed to identify any further transcribed elements within the co-amplified region. The homogeneity of hybridisation patterns and the identification and analysis of a single copy revertant has shown that the amplification is of a direct tandem nature and we propose a model of chromatid misalignment and recombination as its mode of generation. Hybridisation analysis of penicillin non-producing mutants has indicated the loss, in all those investigated, of the entire penicillin biosynthesis gene cluster, similarities between the deletion junctions in these strains and comparison with previously published data indicating the presence of recombinogenic regions flanking the penicillin biosynthesis gene cluster.

Skin testing with penicilloate and penilloate prepared by an improved method: Amoxicillin oral challenge in patients with negative skin test responses to penicillin reagents ☆ ☆☆ ★ ★★

Abstract: Background: Penicillin skin testing has been limited by the lack of commercially available penicilloate and penilloate reagents. Objective: This project was proposed to produce a stable, well-characterized supply of penicilloate and penilloate for intrastate use by our health maintenance organization and to document clinical safety and efficacy. Methods: An improved method of extraction for penicilloate and penilloate, which changed the solvents used during recrystallization, was developed. With these newly prepared reagents, penicillin skin testing was performed on 348 subjects. Skin testing was immediately followed by an oral challenge of 250 mg of amoxicillin in 215 of 288 (75%) subjects displaying a negative response to a battery of penicillin skin tests. Results: Nuclear magnetic resonance and mass spectrometry of the newly produced penicilloate and penilloate showed no evidence of organic contamination. Penicillin skin testing resulted in 17.2% (60 of 348) positive test results, with 20% of the subjects with positive results only responding to the newly produced minor determinants. The rate of mild adverse reactions to penicillin skin testing was 1.1% (4 of 348). The rate of mild acute adverse reactions was 5.1% (11 of 215), and the delayed reaction rate was 0.9% (2 of 215) with the amoxicillin challenge. Conclusions: This improved penicillin minor determinant extraction method allows for the reproducible production of very pure preparations of penicilloate and penilloate. Large-scale penicillin skin testing, followed by amoxicillin challenge if results are negative is feasible in a large group model health maintenance organization operating within a single state with the use of internally produced penicilloate and penilloate and commercially available penicillin, amoxicillin, and penicilloyl polylysine. (J Allergy Clin Immunol 1997;100:586-91.)

Antibiotic resistance in Neisseria meningitidis.

Abstract: Penicillin has long been recognized as the antibiotic of choice for treatment of meningococcal infections, but clinicians have recently become concerned about the susceptibility of meningococci to penicillin and other antibiotics used in the management of meningococcal disease. Strains relatively resistant to penicillin (minimum inhibitory concentrations ranging from 0.1 mg/L to 1.28 mg/L) have been reported from a large number of countries, although the frequency with which such isolates are found varies widely. The mechanism of relative resistance to penicillin involves, at least in part, the production of altered forms of one of the penicillin-binding proteins. Although treatment with penicillin is still effective against these relatively resistant strains, there is evidence that low-dose treatment regimens can fail. beta-Lactamase production in meningococci is extremely rare but has been reported, and this finding is of great concern. Resistance to sulfonamides and rifampin is of particular concern in regard to the management of contacts of patients with meningococcal disease.

Prevalence of serotypes and antimicrobial resistance of streptococcus pneumoniae strains isolated from Brazilian children with invasive infections. Pneumococcal Study Group in Brazil for the SIREVA Project. Regional System for Vaccines in Latin America.

Abstract: A laboratory surveillance study was developed in Brazil in 1993 to determine capsular types and antimicrobial susceptibility of Streptococcus pneumoniae strains. By studying 360 strains isolated from children with invasive infections in three different cities, 8 out of 34 types were identified as being the most prevalent and considered as the reference group for further analyses. This group comprised 77.7% of all strains studied, and includes the types 1, 5, 6A/B, 9V, 14, 19F, 19A, and 23F. The prevalence of this reference group was significantly higher among strains isolated from children with pneumonia than meningitis. Similarly, this group was more prevalent among strains isolated from children 3 to 6 years of age than from children under 2 years of age. Most strains (78.6%) were found to be susceptible to penicillin and only 1.4% showed high resistance to this antibiotic. However, intermediate resistance to penicillin was detected in 20% of the strains. This laboratory surveillance will be ma...

Pneumococcal resistance patterns in Europe.

Abstract: The emergence of Streptococcus pneumoniae strains with decreased susceptibility to penicillin has been reported worldwide over the past 20 years. However, there are striking discrepancies in penicillin susceptibility among various European countries, suggesting that local conditions may affect clonal propagation or de novo selection of resistant strains. In the present study, data on penicillin resistance patterns, antibiotic use and mode of administration, and treatment compliance in five European countries (France, Spain, Germany, Italy, and the UK) were compared. High prevalence rates of penicillin-resistant pneumococci have been reported in Spain and France, where antibiotics are widely prescribed, and overall in Europe, patient compliance with more than 50% of oral antimicrobial prescriptions is inadequate. The low prevalence of penicillin resistance in Germany and the UK coincides with lower antibiotic consumption and better treatment compliance in these countries. Recent attempts to raise public awareness and to restrict and improve indications for antimicrobial agents have resulted in decreased pneumococcal resistance in Hungary and Iceland, suggesting that pneumococcal resistance can be reversed.

High incidence of erythromycin-resistant streptococci in Taiwan.

Abstract: The activities of nine antimicrobial agents against 247 isolates of group B, C, F, and G streptococci and viridans group streptococci were studied by the broth microdilution method. Erythromycin resistance was found in 29.7, 41.7, 81.8, 23.5, and 53.3% of the strains of group B, C, F, and G streptococci and viridans group streptococci tested, respectively. Macrolides are not considered an optimal alternative to penicillin in the treatment of streptococcal infections, at least empirically, in Taiwan.

Nasopharyngeal carriage of community-acquired, antibiotic-resistant Streptococcus pneumoniae in a Zambian paediatric population

Abstract: The emergence of antibiotic-resistant Streptococcus pneumoniae is an international health problem. Apart from South Africa few data on pneumococcal resistance are available for sub-Saharan Africa. This study examines the nasopharyngeal carriage and prevalence of antibiotic resistance in pneumococci isolated from 260 Zambian children aged < 6 years. Pneumococci were isolated from 71.9% of the children; the odds of carrying organisms were twice as high among children < 2 years of age compared with older children. Antibacterial resistance was found in 34.1% of the isolates; resistance to tetracycline, penicillin, sulfamethoxazole + trimethoprim, and chloramphenicol occurred in 23.0%, 14.3%, 12.7%, and 3.9% of the isolates, respectively. Only 4% of the isolates were resistant to three drugs. High-level resistance was found in all isolates resistant to tetracycline; but only intermediate level penicillin resistance was found. A total of 11.1% of the isolates demonstrated intermediate resistance to sulfamethoxazole + trimethoprim. Children aged < 6 months were less likely to carry antibiotic-resistant organisms. Antibiotic resistance in S. pneumoniae appears to be an emerging public health problem in Zambia, and the national policy for the empirical treatment of pneumococcal meningitis and acute respiratory tract infections may need to be re-evaluated. The establishment of ongoing surveillance to monitor trends in pneumococcal resistance should be considered.

Comparison of the in vitro activities of Bay 12-8039, a new quinolone, and other antimicrobials against clinically important anaerobes.

Abstract: Bay 12-8039, a new 8-methoxy quinolone, was compared with other agents for activity against clinically relevant anaerobes. Bay 12-8039 inhibited 91 and 96% of the 410 test isolates at 2 and 4 micrograms/ml, respectively. Bay 12-8039 had activity comparable to that metronidazole and overall was at least 16-fold more active than ciprofloxacin, ofloxacin, and cefoxitin, 32-fold more active than cefotetan, and at least 128-fold more active than penicillin G.

Penicillin-resistant Streptococcus pneumoniae in the Netherlands: results of a 1-year molecular epidemiologic survey.

Abstract: The molecular epidemiologic characteristics of penicillin-resistant pneumococci in the Netherlands were investigated in 1995. Dutch electronic surveillance data showed that 0.7% of all pneumococci were intermediately resistant and 0.4% were highly resistant to penicillin. From March 1995 to March 1996, 89 penicillin-resistant isolates were collected by 39 medical microbiology laboratories. Thirty different genotypes were observed by restriction fragment end labeling. Twenty-one DNA types were unique, whereas 9 distinct genotypes were shared by > or = 2 isolates. Different serogroups were found within 6 of the 9 genetically identical clusters of penicillin-resistant isolates, suggesting that horizontal transfer of capsular genes is common. Finally, nosocomial transmission of penicillin-resistant pneumococci was observed among 21 elderly adults with chronic obstructive pulmonary disease. This study demonstrates that multiple clones of penicillin-resistant pneumococci have been introduced in the Netherlands, a country with a low prevalence of pneumococcal infection. Some clones spread among the population in and outside hospitals.

Resistance Patterns of Streptococcus pneumoniae from Carriers Attending Day-Care Centers in Southwestern Greece

Abstract: The resistance to beta-lactam and non-beta-lactam antibiotics of 133 nasopharyngeal isolates of Streptococcus pneumoniae recovered from December 1995 to February 1996 from children attending seven day-care centers in southwestern Greece was studied. Reduced susceptibility to one or more anti-microbial agents was found in 70 isolates (53%), as follows: penicillin, 17% intermediate, 12% resistant; cefotaxime, 10.5% intermediate, 1.5% resistant; trimethoprim-sulfamethoxazole, 8% intermediate, 35% resistant; chloramphenicol, 27% resistant; tetracycline, 29% resistant; and erythromycin/clindamycin, 19% resistant. Eighty-seven percent of penicillin-intermediate or -resistant strains belonged to serogroups/serotypes 19, 21, and 23. Fifty-six percent of the antibiotic-resistant pneumococci were multiply resistant, including serogroup 6 strains that were penicillin-susceptible but resistant to all non-beta-lactam drugs tested, as well as serogroup 23 strains resistant to penicillin, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole. The high incidence of antibiotic-resistant pneumococci and the divergent and unique resistance patterns found in this study underline the need for global surveillance of S. pneumoniae to document the evolution and spread of resistant strains and to guide therapy.

Susceptibility of pneumococcal carriage isolates to penicillin provides a conservative estimate of susceptibility of invasive pneumococci.

Abstract: Objective.Because of its practical importance for public health monitoring in developing countries, we aimed to determine whether susceptibility to penicillin of pneumococci isolated from the upper respiratory tract (URT) is representative of the susceptibility of pneumococci causing pneumonia in

Skin colonization of Staphylococcus aureus in atopic dermatitis patients seen at the National Skin Centre, Singapore

Abstract: OBJECTIVE This prospective study sought to determine the bacterial colonization rates on eczematous and non-eczematous skin and nasal mucosa of patients with atopic dermatitis attending a tertiary dermatologic referral clinic in Singapore The colonization rates were evaluated according to age, sex, race, and severity of dermatitis compared with controls The results may help to determine whether antibiotics should be considered in the treatment of atopic dermatitis PATIENTS Patients, of any age, presenting with atopic dermatitis at the subsidized clinic of the National Skin Centre, Singapore, between 23 August 1996 and 14 September 1996, were included in the study RESULTS Thirty-three patients with atopic dermatitis were seen at the outpatient clinic during the study period Staphylococcus aureus was isolated in 697% of the eczematous lesions and in 424% of non-eczematous skin of patients with atopic dermatitis S aureus was isolated in 53% of patients with mild dermatitis, and in 100% with moderate and severe dermatitis The nasal carriage rate of S aureus was higher in atopic dermatitis patients (515%) than in non-atopics (35%) (not significant) S aureus was isolated in 42% of non-eczematous skin in atopics compared with only 5% in the control group (p = 0003) In patients with atopic dermatitis, all S aureus isolated was sensitive to cloxacillin, cephalexin, clindamycin, and co-trimoxazole; 92% was sensitive to erythromycin, but only 13% was sensitive to penicillin and ampicillin In the control group, all S aureus isolated was sensitive to cloxacillin, cephalexin, erythromycin, clindamycin, and co-trimoxazole, but only 13% was sensitive to penicillin and ampicillin, and 87% to tetracycline CONCLUSIONS This study confirmed that the skin of patients with atopic dermatitis was more frequently colonized with S aureus than that of non-atopics The more severe the dermatitis, the higher the rate of colonization S aureus is also more of than present in non-eczematous skin of atopics than of non-atopics There is also a higher percentage of S aureus nasal carriage in patients with atopic dermatitis than in non-atopics Hence antibiotics may have a role in the treatment of atopic dermatitis Because 87% of S aureus is resistant to penicillin and ampicillin, antibiotics such as cloxacillin and cephalexin should be used to eradicate S aureus in the skin of atopic dermatitis individuals

Selection of Glycopeptide-Resistant Mutants of VanB-Type Enterococcus faecaiis BM4281 In Vitro and in Experimental Endocarditis

Abstract: Enterococcusfaecalis BM4281 is resistant to vancomycin, susceptible to teicoplanin (VanB pheno­ type), and intrinsically resistant to low levels of gentamicin. The efficacy of glycopeptides against BM4281 was investigated in a rabbit model of experimental endocarditis for reduction of bacterial counts in cardiac vegetations and selection of mutants with increased resistance to glycopeptides. Teicoplanin led to a lOO-fold reduction of bacteria in the vegetations, whereas vancomycin had no effect. Monotherapy with either antibiotic selected mutants with homogeneous or heterogeneous resistance to high levels of both glycopeptides. Vancomycin also selected mutants that required the antibiotic for growth. The combination of gentamicin plus teicoplanin was bactericidal, prevented the emergence of mutants, and allowed sterilization of the vegetations in 25% of the rabbits, indicat­ ing that the combination may be an alternative if penicillin cannot be used against VanB-type enterococci.

In vitro activity of Bay 12-8039, a new 8-methoxyquinolone, compared to the activities of 11 other oral antimicrobial agents against 390 aerobic and anaerobic bacteria isolated from human and animal bite wound skin and soft tissue infections in humans.

Abstract: The in vitro activity of Bay 12-8039, a new oral 8-methoxyquinolone, was compared to the activities of 11 other oral antimicrobial agents (ciprofloxacin, levofloxacin, ofloxacin, sparfloxacin, azithromycin, clarithromycin, amoxicillin clavulanate, penicillin, cefuroxime, cefpodoxime, and doxycycline) against 250 aerobic and 140 anaerobic bacteria recently isolated from animal and human bite wound infections. Bay 12-8039 was active against all aerobic isolates, both gram-positive and gram-negative isolates, at or = 4.0 microg/ml) and one strain of Prevotella loeschii (MICs, 2.0 microg/ml). In comparison, the other quinolones tested had similar in vitro activities against the aerobic strains but were less active against the anaerobes, including peptostreptococci, Porphyromonas species, and Prevotella species. The fusobacteria were relatively resistant to all the antimicrobial agents tested except penicillin G (one penicillinase-producing strain of F. nucleatum was found) and amoxicillin clavulanate.

Epidemiology of pneumococcal serotypes and conjugate vaccine formulations

Abstract: The incidence of bacteremia and meningitis due to Streptococcus pneumoniae is highest among preschool-age children, particularly those 0.1 microgram/mL, 56 (80%) were among the seven most prevalent serotypes. All 21 isolates resistant to penicillin (MIC > or = 2.0 micrograms/mL) were among these seven serotypes.

Comparative Susceptibility of Clinical Group A, B, C, F, and G β-Hemolytic Streptococcal Isolates to 24 Antimicrobial Drugs

Abstract: A total of 312 clinical beta-hemolytic streptococcal isolates (Streptococcus pyogenes, group A = 63; Streptococcus agalactiae, group B = 145; group C = 50; group F = 27; group G = 27) were examined for susceptibility to 23 and 24 antimicrobial drugs with the Bauer-Kirby agar disk diffusion and the agar dilution method, respectively. Sheep blood Mueller-Hinton agar served as the reference medium. Wilkins-Chalgren agar supported optimal growth of group A and B, but not of all group C, F, and G streptococci. The group A streptococci were susceptible to all beta-lactam antibiotics, clindamycin, chloramphenicol, rifampin, teicoplanin, and vancomycin, but resistant to cotrimoxazole, fusidic acid, and, except for 2 strains, to fosfomycin. Resistance (R)/intermediate susceptibility (I) rates (R/I%) to ciprofloxacin (0/2%), ofloxacin (1/2%), erythromycin (1.6/0%), and clarithromycin (0/1%) were low. Higher resistance rates were noted with tetracyclines (doxycycline 23.8/15.9%; tetracycline 39.7/3.2%). Among the group B streptococcal isolates, one strain was resistant against oxacillin and of intermediate susceptibility to penicillin G and cefoxitin. All isolates were susceptible to teicoplanin and rifampin. Conversely, all group B isolates were resistant to cotrimoxazole and fusidic acid; 69% and 51% of these isolates were susceptible to fosfomycin and rifampin, respectively. R/I rates of the group B streptococcal isolates were low for ciprofloxacin and ofloxacin (0/0.7%), clindamycin (0.7/0%), erythromycin (1.4/ 3.5%), clarithromycin (1.4/0%), and chloramphenicol (0.7/0%). Resistance to tetracyclines was significant (doxycycline: 72.4/2.1%; tetracycline; 74.5/1.4%). Among the non-A, non-B beta-hemolytic streptococci, 2 group C strains were resistant to oxacillin and showed intermediate susceptibility to penicillin G. All isolates were susceptible to third and fourth-generation cephalosporins, imipenem, chloramphenicol, rifampin, teicoplanin, and vancomycin. R/I rates to the other antimicrobial drugs were: ciprofloxacin (3.9/1.9%), ofloxacin (2.9/1.9%), clindamycin (2.9/1%), erythromycin (5.8/0%), clarithromycin (3.8/2.9%), and cotrimoxazole (16.4/3.9%). Resistance against tetracyclines was more frequent (doxycycline: 18.3/2.9%; tetracycline: 20.2/6.7%). On the basis of various minor discrepancies between MIC and disk diffusion test results, it is proposed that the current NCCLS inhibition zone (diameter, mm) criteria indicative of intermediate susceptibility of beta-hemolytic streptococci be changed for the following antimicrobial drugs: ampicillin: 22-27 mm (only for group A and B beta-hemolytic streptococci); ciprofloxacin: 16-18 mm; clindamycin: 15-18 mm; doxycycline: 17-19 mm; tetracycline: 17-19 mm, and erythromycin: 14-19 mm.

Apparent failure of one injection of benzathine penicillin G for syphilis during pregnancy in human immunodeficiency virus-seronegative African women.

Abstract: To determine whether the US Centers for Disease Control guideline of 1 injection of 2.4 million U of benzathine penicillin G is sufficient treatment for early syphilis in pregnant women this regimen was tested in 180 human immunodeficiency virus-negative urban Black women with syphilis presenting to Kalafong Hospital in Pretoria South Africa during 1988-90. A favorable pregnancy outcome was recorded in 108 women who received 2 or 3 weekly intragluteal injections. On the other hand 1 injection was associated with lower birth weight increased prematurity and total preterm birth rate and increased total pregnancy loss and neonatal mortality. These outcomes were reanalyzed after exclusion of women treated with oral penicillin derivatives and adjusted for the estimated duration of treponemicidal levels at 3 weeks post-injection. Birth weight was significantly lower for treponemicidal coverage of 3 weeks or less compared to coverage lasting more than 3 weeks (2748 and 3130 grams respectively). Also increased when coverage was less than 3 weeks were the relative risks for prematurity (8.5) perinatal mortality (20.5) and congenital syphilis (2.0). Impaired outcome associated with short treatment was clustered in women who attended prenatal care before the 28th week of gestation and those whose initial rapid plasma reagin titer exceeded 16. These findings indicate that the standard protocol is not adequate in areas where syphilis is endemic. Recommended is administration of 2 injections of 2.4 million U benzathine penicillin at least 1 week apart preferably 4 weeks or more before delivery.