Impact of amoxicillin therapy on resistance selection in patients with community-acquired lower respiratory tract infections: a randomized, placebo-controlled study.

OBJECTIVES: To determine the effect of amoxicillin treatment on resistance selection in patients with community-acquired lower respiratory tract infections in a randomized, placebo-controlled trial. METHODS: Patients were prescribed amoxicillin 1 g, three times daily (n = 52) or placebo (n = 50) for 7 days. Oropharyngeal swabs obtained before, within 48 h post-treatment and at 28-35 days were assessed for proportions of amoxicillin-resistant (ARS; amoxicillin MIC ≥2 mg/L) and -non-susceptible (ANS; MIC ≥0.5 mg/L) streptococci. Alterations in amoxicillin MICs and in penicillin-binding-proteins were also investigated. ITT and PP analyses were conducted. RESULTS: ARS and ANS proportions increased 11- and 2.5-fold, respectively, within 48 h post-amoxicillin treatment compared with placebo [ARS mean increase (MI) 9.46, 95% CI 5.57-13.35; ANS MI 39.87, 95% CI 30.96-48.78; P < 0.0001 for both]. However, these differences were no longer significant at days 28-35 (ARS MI -3.06, 95% CI -7.34 to 1.21; ANS MI 4.91, 95% CI -4.79 to 14.62; P > 0.1588). ARS/ANS were grouped by pbp mutations. Group 1 strains exhibited significantly lower amoxicillin resistance (mean MIC 2.8 mg/L, 95% CI 2.6-3.1) than group 2 (mean MIC 9.3 mg/L, 95% CI 8.1-10.5; P < 0.0001). Group 2 strains predominated immediately post-treatment (61.07%) and although decreased by days 28-35 (30.71%), proportions remained higher than baseline (18.70%; P = 0.0004). CONCLUSIONS: By utilizing oropharyngeal streptococci as model organisms this study provides the first prospective, experimental evidence that resistance selection in patients receiving amoxicillin is modest and short-lived, probably due to 'fitness costs' engendered by high-level resistance-conferring mutations. This evidence further supports European guidelines that recommend amoxicillin when an antibiotic is indicated for community-acquired lower respiratory tract infections.

In vitro efficacy of various topical antimicrobial agents in different time periods from contamination to application against 6 multidrug-resistant bacterial strains isolated from burn patients.

AIM: In vitro efficacy evaluation of eleven topical antimicrobials against multidrug-resistant (MDR) bacteria isolated from burn wounds of our patients. MATERIAL AND METHODS: Growth of six MDR bacterial strains: Pseudomonas aeruginosa (2 strains), Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis and Escherichia coli in burn-wound models was evaluated 24-h after application of the tested agents. Four different wound models were created to investigate the role of time elapsed between inoculation of bacteria and application of the agents on their antimicrobial activity and efficacy. RESULTS: The efficacy against all the 6 bacteria in freshly contaminated wounds was excellent in majority of the tested agents. The longer was the time interval between inoculation and application of the topical antimicrobial agents, the higher failure of the agents was observed. CONCLUSIONS: Topical antimicrobials play an important role in treatment of burn wounds, but they should be used according to their efficacy against bacterial strains present in patients' wounds. In cases where topical agents have been applied after 24 h, when formation of mature biofilm in the wound could be expected, it would probably not be possible to kill all the bacteria using topical antimicrobial therapy only.

Rosmarinic acid interaction with planktonic and biofilm Staphylococcus aureus.

The subject of study was the evaluation of antibacterial activities of rosmarinic acid (RA) on clinical Staphylococcus aureus strains obtained from catheter-related infections. Minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC) of RA were tested by broth microdilution assay. Biofilm-eradication activity was detected on 24-hour biofilm in microtiter plates using a regrowth technique; activity on biofilm formation was measured by a microtiter plate method after RA application to bacterial samples after 0, 1, 3 and 6 hours of biofilm development. RA had antimicrobial activity on all tested strains in concentrations from 625 to 1250 microg.mL-1 (MICs equal to MBCs). No biofilm-eradication activity on 24-hour biofilm was observed in the tested range of concentrations (from 156 to 5000 microg.mL-1). Subinhibitory RA concentrations suppressed the biofilm production, when applied at early stages of its development. Concentrations lower than subinhibitory stimulated the biofilm mass production in a concentration- and time-dependent manner. Considering our results, RA could be a candidate for a topical antimicrobial agent with killing activity on planktonic forms of bacteria and suppressing activity in the early stages of biofilm development, but probably not for the therapy of catheter-related infections as a sole agent.

Involvement of virulence properties and antibiotic resistance in Escherichia coli strains causing pyelonephritis in children.

A total of 145 Escherichia coli strains causing pyelonephritis in children were investigated for the prevalence of genes encoding the following virulence factors (VFs): P fimbria (67.6 %), S fimbria (53.8 %), AFA adhesins (2.8 %), cytotoxic necrotizing factor 1 (37.9 %), α-hemolysin (41.4 %), and aerobactin (71.7 %). One hundred and thirty-six (93.8 %) isolates harbored at least one of the virulence genes detected in the present study. Statistically significant co-occurrent presence of two VF genes was found for α-hly-cnf1, α-hly-sfa, cnf1-sfa (p<0.001), and α-hly-pap (p=0.001). Twenty-six profiles of VF genes were detected in this study. The combinations of aer-pap and aer-pap-sfa-α-hly-cnf1 were presented with the highest frequency-both of them in 28 isolates (19.3 %). All E. coli strains included in the study were susceptible to meropenem, amikacin, and tobramycin; the highest frequency resistance was found toward ampicillin (43.4 %), piperacillin (31.7 %), tetracycline (15.9 %), and trimethoprim/sulfamethoxazole (11.7 %). The resistance to the other tested antimicrobial drugs did not exceed 3 % incidence. Overall, 55.9 % strains were susceptible to all tested anti-infective agents. Antimicrobial resistance of E. coli strains toward trimethoprim/sulfamethoxazole statistically significantly correlated with the presence of α-hly (p<0.001), sfa (p<0.01), and cnf1 (p<0.05).

Amoxicillin for acute lower-respiratory-tract infection in primary care when pneumonia is not suspected: a 12-country, randomised, placebo-controlled trial.

BACKGROUND: Lower-respiratory-tract infection is one of the most common acute illnesses managed in primary care. Few placebo-controlled studies of antibiotics have been done, and overall effectiveness (particularly in subgroups such as older people) is debated. We aimed to compare the benefits and harms of amoxicillin for acute lower-respiratory-tract infection with those of placebo both overall and in patients aged 60 years or older. METHODS: Patients older than 18 years with acute lower-respiratory-tract infections (cough of ≤28 days' duration) in whom pneumonia was not suspected were randomly assigned (1:1) to either amoxicillin (1 g three times daily for 7 days) or placebo by computer-generated random numbers. Our primary outcome was duration of symptoms rated "moderately bad" or worse. Secondary outcomes were symptom severity in days 2-4 and new or worsening symptoms. Investigators and patients were masked to treatment allocation. This trial is registered with EudraCT (2007-001586-15), UKCRN Portfolio (ID 4175), ISRCTN (52261229), and FWO (G.0274.08N). FINDINGS: 1038 patients were assigned to the amoxicillin group and 1023 to the placebo group. Neither duration of symptoms rated "moderately bad" or worse (hazard ratio 1.06, 95% CI 0.96-1.18; p=0.229) nor mean symptom severity (1.69 with placebo vs 1.62 with amoxicillin; difference -0.07 [95% CI -0.15 to 0.007]; p=0.074) differed significantly between groups. New or worsening symptoms were significantly less common in the amoxicillin group than in the placebo group (162 [15.9%] of 1021 patients vs 194 [19.3%] of 1006; p=0.043; number needed to treat 30). Cases of nausea, rash, or diarrhoea were significantly more common in the amoxicillin group than in the placebo group (number needed to harm 21, 95% CI 11-174; p=0.025), and one case of anaphylaxis was noted with amoxicillin. Two patients in the placebo group and one in the amoxicillin group needed to be admitted to hospital; no study-related deaths were noted. We noted no evidence of selective benefit in patients aged 60 years or older (n=595). INTERPRETATION: When pneumonia is not suspected clinically, amoxicillin provides little benefit for acute lower-respiratory-tract infection in primary care both overall and in patients aged 60 years or more, and causes slight harms. FUNDING: European Commission Framework Programme 6, UK National Institute for Health Research, Barcelona Ciberde Enfermedades Respiratorias, and Research Foundation Flanders.

Incidental chest radiographic findings in adult patients with acute cough.

PURPOSE: Imaging may produce unexpected or incidental findings with consequences for patients and ordering of future investigations. Chest radiography in patients with acute cough is among the most common reasons for imaging in primary care, but data on associated incidental findings are lacking. We set out to describe the type and prevalence of incidental chest radiography findings in primary care patients with acute cough. METHODS: We report on data from a cross-sectional study in 16 European primary care networks on 3,105 patients with acute cough, all of whom were undergoing chest radiography as part of a research study workup. Apart from assessment for specified signs of pneumonia and acute bronchitis, local radiologists were asked to evaluate any additional finding on the radiographs. For the 2,823 participants with good-quality chest radiographs, these findings were categorized according to clinical relevance based on previous research evidence and analyzed for type and prevalence by network, sex, age, and smoking status. RESULTS: Incidental findings were reported in 19% of all participants, and ranged from 0% to 25% by primary care network, with the network being an independent contributor (P <.001). Of all participants 3% had clinically relevant incidental findings. Suspected nodules and shadows were reported in 1.8%. Incidental findings were more common is older participants and smokers (P <. 001). CONCLUSIONS: Clinically relevant incidental findings on chest radiographs in primary care adult patients with acute cough are uncommon, and prevalence varies by setting.

Airway obstruction and bronchodilator responsiveness in adults with acute cough.

PURPOSE: We sought to determine the prevalence of airway obstruction and bronchodilator responsiveness in adults consulting for acute cough in primary care. METHODS: Family physicians recruited 3,105 adult patients with acute cough (28 days or shorter) attending primary care practices in 12 European countries. After exclusion of patients with preexisting physician-diagnosed asthma or chronic obstructive pulmonary disease (COPD), we undertook complete case analysis of spirometry results (n = 1,947) 28 to 35 days after inclusion. Bronchodilator responsiveness was diagnosed if there were recurrent complaints of wheezing, cough, or dyspnea and an increase of the forced expiratory volume in 1 second (FEV(1)) of 12% or more after bronchodilation. Airway obstruction was diagnosed according to 2 thresholds for the (postbronchodilator) ratio of FEV(1) to forced vital capacity (FEV(1):FVC): less than 0.7 and less than the lower limit of normal. RESULTS: There were 240 participants who showed bronchodilator responsiveness (12%), 193 (10%) had a FEV(1)/FVC ratio of less than 0.7, and 126 (6%) had a ratio of less than the lower limit of normal. Spearman's correlation between the 2 definitions of obstruction was 0.71 (P <.001), with discordance most pronounced among those younger than 30 years and in older participants. CONCLUSIONS: Both bronchodilator responsiveness and persistent airway obstruction are common in adults without established asthma or COPD who consult for acute cough in primary care, which suggests a high risk of undiagnosed asthma and COPD. Different accepted methods to define airway obstruction detected different numbers of patients, especially at the extremes of age. As both conditions benefit from appropriate and timely interventions, clinicians should be aware and responsive to potential underdiagnosis.

Treatment of acute cough/lower respiratory tract infection by antibiotic class and associated outcomes: a 13 European country observational study in primary care.

OBJECTIVES: Acute cough/lower respiratory tract infection (LRTI) is one of the commonest reasons for consulting and antibiotic prescribing. There are theoretical reasons why treatment with particular antibiotic classes may aid recovery more than others, but empirical, pragmatic evidence is lacking. We investigated whether treatment with a particular antibiotic class (amoxicillin) was more strongly associated with symptom score resolution and time to patients reporting recovery than each of eight other antibiotic classes or no antibiotic treatment for acute cough/LRTI. METHODS: Clinicians recorded history, examination findings, symptom severity and antibiotic treatment for 3402 patients in a 13 country prospective observational study of adults presenting in 14 primary care research networks with acute cough/LRTI. 2714 patients completed a symptom score daily for up to 28 days and recorded the day on which they felt recovered. A three-level autoregressive moving average model (1,1) model investigated logged daily symptom scores to analyse symptom resolution. A two-level survival model analysed time to reported recovery. Clinical presentation was controlled for using clinician-recorded symptoms, sputum colour, temperature, age, co-morbidities, smoking status and duration of illness prior to consultation. RESULTS: Compared with amoxicillin, no antibiotic class (and no antibiotic treatment) was associated with clinically relevant improved symptom resolution (all coefficients in the range -0.02 to 0.01 and all P values greater than 0.12). No antibiotic class (and no antibiotic treatment) was associated with faster time to recovery than amoxicillin. CONCLUSIONS: Treatment by antibiotic class was not associated with symptom resolution or time to recovery in adults presenting to primary care with acute cough/LRTI.

[Monitoring the prevalence of Streptococcus pneumoniae in various groups]. / Monitoring prevalencie Streptococcus pneumoniae v rôznych kolektívoch.

BACKGROUND: The aim of the present study was to monitor the nasopharyngeal presence of Streptococcus pneumoniae in different age groups (especially children) in Banská Bystrica, Slovakia. The purpose of this screening was to determine the prevalence of different serotypes and to follow up the presence of pneumococcus in these children after the vaccination with heptavalent protein-conjugate vaccine. A contribution of molecular biology techniques was the detection of S. pneumoniae DNA by PCR and also the typisation and comparison of pneumococcal strains by pulsed-field gel electrophoresis. METHODS: S. pneumoniae in nasopharyngeal swabs was detected by cultivation on blood agar plates. Serotypisation was performed by standard Quellung reaction. The commercial diagnostic kit was used for PCR detection of S. pneumoniae DNA. Pulsed-field electrophoresis was performed by modified scheme according to literature. RESULTS: The incidence of pneumococcus is decreasing and less significant with the increasing age. Among youngest children is relatively high prevalence of pneumococci and the relatedness of isolated strains is high as well. After the vaccination, the less invasive serotypes were detected, although the overall incidence of S. pneumoniae was similar. CONCLUSIONS: The monitoring of S. pneumoniae in population is important according to variability of this bacteria with respect to possible changes in pneumococcal types as a consequence of vaccination.

Resistance to macrolides in clinical isolates of Streptococcus pyogenes due to ribosomal mutations.

OBJECTIVE: Two clinical strains of Streptococcus pyogenes, 237 and 544, one isolated in Slovakia and the other in Croatia, that were resistant to azithromycin (MIC 8 and 2 mg/L, respectively) but susceptible to erythromycin (MIC 0.5 and 0.12 mg/L, respectively) did not contain any gene known to confer macrolide resistance by ribosomal modification (erm gene) or efflux [mef(A) and msr(A) genes]. The aim of the study was to determine the mechanisms of macrolide resistance in both strains. METHODS: Portions of genes encoding ribosomal proteins L22 and L4, and 23S rRNA (domains II and V) in the two macrolide-resistant strains and in control strains susceptible to macrolides, were analysed by PCR and single-strand conformational polymorphism, to screen for mutations. The DNA sequences of amplicons from resistant strains that differed from those of susceptible strains, in terms of their electrophoretic migration profiles, were determined. RESULTS: S. pyogenes 237 displayed a KG insertion after position 69 in ribosomal protein L4. S. pyogenes 544 contained a C2611U mutation in domain V of 23S rRNA. CONCLUSION: Mutations at a similar position in ribosomal protein L4 and 23S rRNA have been reported previously in macrolide-resistant pneumococci. This report shows that similar mutations can be found in macrolide-resistant S. pyogenes.

Susceptibilities to telithromycin and six other agents and prevalence of macrolide resistance due to L4 ribosomal protein mutation among 992 Pneumococci from 10 central and Eastern European countries.

The macrolide and levofloxacin susceptibilities of 992 isolates of Streptococcus pneumoniae from clinical specimens collected in 1999 and 2000 were determined in 10 centers in Central and Eastern European countries. The prevalences of penicillin G-intermediate (MICs, 0.125 to 1 microg/ml) and penicillin-resistant (MICs, < or =2 microg/ml) Streptococcus pneumoniae isolates were 14.3 and 16.6%, respectively. The MICs at which 50% of isolates are inhibited (MIC(50)s) and the MIC(90)s of telithromycin were 0.016 and 0.06 microg/ml, respectively; those of erythromycin were 0.06 and >64 microg/ml, respectively; those of azithromycin were 0.125 and >64 microg/ml, respectively; those of clarithromycin were 0.03 and >64 microg/ml, respectively; and those of clindamycin were 0.06 and >64 microg/ml, respectively. Erythromycin resistance was found in 180 S. pneumoniae isolates (18.1%); the highest prevalence of erythromycin-resistant S. pneumoniae was observed in Hungary (35.5%). Among erythromycin-resistant S. pneumoniae isolates, strains harboring erm(B) genes (125 strains [69.4%]) were found to be predominant over strains with mef(E) genes (25 strains [13.4%]), L4 protein mutations (28 strains [15.6%]), and erm(A) genes (2 strains [1.1%]). Similar pulsed-field gel electrophoresis patterns suggested that some strains containing L4 mutations from the Slovak Republic, Bulgaria, and Latvia were clonally related. Of nine strains highly resistant to levofloxacin (MICs, >8 microg/ml) six were isolated from Zagreb, Croatia. Telithromycin at < or =0.5 microg/ml was active against 99.8% of S. pneumoniae isolates tested and may be useful for the treatment of respiratory tract infections caused by macrolide-resistant S. pneumoniae isolates.

Susceptibility to telithromycin in 1,011 Streptococcus pyogenes isolates from 10 central and Eastern European countries.

Among 1,011 recently isolated Streptococcus pyogenes isolates from 10 Central and Eastern European centers, the MICs at which 50% of isolates are inhibited (MIC(50)s) and the MIC(90)s were as follows: for telithromycin, 0.03 and 0.06 microg/ml, respectively; for erythromycin, azithromycin, and clarithromycin, 0.06 to 0.125 and 1 to 8 microg/ml, respectively; and for clindamycin, 0.125 and 0.125 microg/ml, respectively. Erythromycin resistance occurred in 12.3% of strains. Erm(A) [subclass erm(TR)] was most commonly encountered (60.5%), followed by mef(A) (23.4%) and erm(B) (14.5%). At <0.5 microg/ml, telithromycin was active against 98.5% of the strains tested.