Antimicrobial resistance in Streptococcus pneumoniae: implications for patients with community-acquired pneumonia

Isorhamnetin as a novel inhibitor of pneumolysin against Streptococcus pneumoniae infection in vivo/in vitro

The increasing incidence of Streptococcus pneumoniae (S. pneumoniae) infection severely threatened the global public heath, causing a significant fatality in immunocompromised hosts. Notably, pneumolysin (PLY) as a pore-forming cytolysin plays a crucial role in the pathogenesis of pneumococcal pneumonia and lung injury. In this study, a natural flavonoid isorhamnetin was identified as a PLY inhibition to suppress PLY-induced hemolysis by engaging the predicted residues and attenuate cytolysin PLY-mediated A549 cells injury. Underlying mechanisms revealed that PLY inhibitor isorhamnetin further contributed to decrease the formation of bacterial biofilms without affecting the expression of PLY. In vivo S. pneumoniae infection confirmed that the pathological injury of lung tissue evoked by S. pneumoniae was ameliorated by isorhamnetin treatment. Collectively, these results presented that isorhamnetin could inhibit the biological activity of PLY, thus reducing the pathogenicity of S. pneumoniae. In summary, our study laid a foundation for the feasible anti-virulence strategy targeting PLY, and provided a promising PLY inhibitor for the treatment of S. pneumoniae infection.

A Review of the Resistance Mechanisms for β-Lactams, Macrolides and Fluoroquinolones among Streptococcus pneumoniae

Streptococcus pneumoniae (S. pneumoniae) is a bacterial species often associated with the occurrence of community-acquired pneumonia (CAP). CAP refers to a specific kind of pneumonia that occurs in individuals who acquire the infection outside of a healthcare setting. It represents the leading cause of both death and morbidity on a global scale. Moreover, the declaration of S. pneumoniae as one of the 12 leading pathogens was made by the World Health Organization (WHO) in 2017. Antibiotics like β-lactams, macrolides, and fluoroquinolones are the primary classes of antimicrobial medicines used for the treatment of S. pneumoniae infections. Nevertheless, the efficacy of these antibiotics is diminishing as a result of the establishment of resistance in S. pneumoniae against these antimicrobial agents. In 2019, the WHO declared that antibiotic resistance was among the top 10 hazards to worldwide health. It is believed that penicillin-binding protein genetic alteration causes β-lactam antibiotic resistance. Ribosomal target site alterations and active efflux pumps cause macrolide resistance. Numerous factors, including the accumulation of mutations, enhanced efflux mechanisms, and plasmid gene acquisition, cause fluoroquinolone resistance. Furthermore, despite the advancements in pneumococcal vaccinations and artificial intelligence (AI), it is not feasible for individuals to rely on them indefinitely. The ongoing development of AI for combating antimicrobial resistance necessitates more research and development efforts. A few strategies can be performed to curb this resistance issue, including providing educational initiatives and guidelines, conducting surveillance, and establishing new antibiotics targeting another part of the bacteria. Hence, understanding the resistance mechanism of S. pneumoniae may aid researchers in developing a more efficacious antibiotic in future endeavors.

Catheter-associated urinary tract infections in patients who have undergone radical cystectomy for bladder cancer: A prospective randomized clinical study of two silicone catheters (clinical benefit of antibiotic silicone material)

Purpose

Materials and Methods

Results

Conclusions

Clinical Features and Outcomes of Streptococcus pneumoniae Meningitis in Children: A Retrospective Analysis of 26 Cases in China

BACKGROUND

Streptococcus pneumoniae is an important cause of pediatric meningitis.

OBJECTIVE

The aim of this study was to analyze the clinical features and outcomes of children with pneumococcal meningitis at our hospital in China, so as to provide basis for improving the clinical treatment effect.

METHODS

This retrospective analysis included patients aged <16 years treated for pneumococcal meningitis at the Department of Neurology, Children's Hospital of Shanxi (January 2014-February 2016). Clinical data were extracted from the medical records. Patients were followed up for 6 months after discharge.

RESULTS

The analysis included 26 children aged 2 months to 13 years, with 17 (65.4%) aged <3 years. Presenting symptoms included fever (100%), lethargy (100%), impaired consciousness (88.5%), neck stiffness (69.2%), seizures (53.8%), and headache (50.0%). All patients had positive cerebrospinal fluid (CSF) cultures. The final treatment was vancomycin combined with a third-generation cephalosporin or other antibiotics in 25 patients. Eleven patients (42.3%) were recovered, 3 (11.5%) had neurological sequelae, and 12 (46.2%) died. Impaired consciousness (p = 0.035), cerebral hernia (p = 0.037), respiratory failure (p = 0.004), heart failure (p = 0.044), septic shock (p = 0.037), low CSF white blood cell count (p = 0.036), high CSF protein levels (p = 0.028), low white blood cell count (p = 0.036), and low blood neutrophil ratio (p = 0.016) are associated with a poor prognosis to pneumococcal meningitis.

CONCLUSION

Pneumococcal meningitis is associated with a poor prognosis in many children. Poor prognosis might be related to early ineffective antibiotic therapy, a combination of systemic failure, neurological problems, and changed inflammatory response. It is important to rapid initiation of appropriate antibiotic therapy if meningitis is suspected.

Highlights Regarding the Use of Metallic Nanoparticles against Pathogens Considered a Priority by the World Health Organization

The indiscriminate use of antibiotics has facilitated the growing resistance of bacteria, and this has become a serious public health problem worldwide. Several microorganisms are still resistant to multiple antibiotics and are particularly dangerous in the hospital and nursing home environment, and to patients whose care requires devices, such as ventilators and intravenous catheters. A list of twelve pathogenic genera, which especially included bacteria that were not affected by different antibiotics, was released by the World Health Organization (WHO) in 2017, and the research and development of new antibiotics against these genera has been considered a priority. The nanotechnology is a tool that offers an effective platform for altering the physicalchemical properties of different materials, thereby enabling the development of several biomedical applications. Owing to their large surface area and high reactivity, metallic particles on the nanometric scale have remarkable physical, chemical, and biological properties. Nanoparticles with sizes between 1 and 100 nm have several applications, mainly as new antimicrobial agents for the control of microorganisms. In the present review, more than 200 reports of various metallic nanoparticles, especially those containing copper, gold, platinum, silver, titanium, and zinc were analyzed with regard to their anti-bacterial activity. However, of these 200 studies, only 42 reported about trials conducted against the resistant bacteria considered a priority by the WHO. All studies are in the initial stage, and none are in the clinical phase of research.

Hemoglobin Induces Early and Robust Biofilm Development in Streptococcus pneumoniae by a Pathway That Involves comC but Not the Cognate comDE Two-Component System

Streptococcus pneumoniae grows in biofilms during both asymptomatic colonization and infection. Pneumococcal biofilms on abiotic surfaces exhibit delayed growth and lower biomass and lack the structures seen on epithelial cells or during nasopharyngeal carriage. We show here that adding hemoglobin to the medium activated unusually early and vigorous biofilm growth in multiple S. pneumoniae serotypes grown in batch cultures on abiotic surfaces. Human blood (but not serum, heme, or iron) also stimulated biofilms, and the pore-forming pneumolysin, ply, was required for this induction. S. pneumoniae transitioning from planktonic into sessile growth in the presence of hemoglobin displayed an extensive transcriptome remodeling within 1 and 2 h. Differentially expressed genes included those involved in the metabolism of carbohydrates, nucleotides, amino acid, and lipids. The switch into adherent states also influenced the expression of several regulatory systems, including the comCDE genes. Inactivation of comC resulted in 67% reduction in biofilm formation, while the deletion of comD or comE had limited or no effect, respectively. These observations suggest a novel route for CSP-1 signaling independent of the cognate ComDE two-component system. Biofilm induction and the associated transcriptome remodeling suggest hemoglobin serves as a signal for host colonization in pneumococcus.

Emerging concepts in the pathogenesis of the Streptococcus pneumoniae: From nasopharyngeal colonizer to intracellular pathogen

Streptococcus pneumoniae (the pneumococcus) is a human respiratory tract pathogen and a major cause of morbidity and mortality globally. Although the pneumococcus is a commensal bacterium that colonizes the nasopharynx, it also causes lethal diseases such as meningitis, sepsis, and pneumonia, especially in immunocompromised patients, in the elderly, and in young children. Due to the acquisition of antibiotic resistance and the emergence of nonvaccine serotypes, the pneumococcus has been classified as one of the priority pathogens for which new antibacterials are urgently required by the World Health Organization, 2017. Understanding molecular mechanisms behind the pathogenesis of pneumococcal infections and bacterial interactions within the host is crucial to developing novel therapeutics. Previously considered to be an extracellular pathogen, it is becoming evident that pneumococci may also occasionally establish intracellular niches within the body to escape immune surveillance and spread within the host. Intracellular survival within host cells also enables pneumococci to resist many antibiotics. Within the host cell, the bacteria exist in unique vacuoles, thereby avoiding degradation by the acidic lysosomes, and modulate the expression of its virulence genes to adapt to the intracellular environment. To invade and survive intracellularly, the pneumococcus utilizes a combination of virulence factors such as pneumolysin (PLY), pneumococcal surface protein A (PspA), pneumococcal adhesion and virulence protein B (PavB), the pilus‐1 adhesin RrgA, pyruvate oxidase (SpxB), and metalloprotease (ZmpB). In this review, we discuss recent findings showing the intracellular persistence of Streptococcus pneumoniae and its underlying mechanisms.

Comparative Proteomics of Streptococcus pneumoniae Response to Vancomycin Treatment

Streptococcus pneumoniae is a gram-positive pathogen that causes otitis media, pneumonia, meningitis, and other serious diseases. Vancomycin is one of the most important drugs currently used for the treatment of gram-positive bacterial infections, representing, importantly, the last line of defense against bacteria that have developed resistance to other antibiotics. While primary efforts of most investigations focused on the antibacterial mechanism of vancomycin, few studies have been performed to assess the tolerance mechanism of bacteria to vancomycin. In this work, whole cellular proteins were extracted from S. pneumoniae D39 with or without vancomycin treatment. Subsequently, differentially expressed proteins (DEPs) were identified with two-dimensional gel electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectrometry (MS)/MS. In total, 27 proteins were upregulated and four proteins were downregulated in vancomycin-treated S. pneumoniae. Gene ontology analysis indicated that these DEPs were mainly involved in the nucleic acid, protein, and carbohydrate biosynthetic processes. Verification experiments with real-time quantitative polymerase chain reaction showed that the gene expression profiles were consistent with proteomic data. These new observations may serve as a valuable resource for future investigations of vancomycin tolerance mechanisms of S. pneumoniae.

The Impact of Prior Antibiotic Therapy on Outcomes in Children Hospitalized for Community-Acquired Pneumonia

Here, we review current available literature regarding the effect of prior antibiotic treatment on outcomes of children hospitalized for community-acquired pneumonia (CAP). To date, no prospective trial has reported information regarding morbidity or mortality in this group of patients. Retrospective studies have provided evidence for the advantage of treatment with broad-spectrum antibiotics in children who failed prior antibiotic therapy. We discuss the changing epidemiology of CAP in the post PCV13 and Hib vaccines era and its relevance to the outcome of pediatric patients hospitalized for CAP. Current studies still report Streptococcus pneumoniae as the most common typical bacterial causative agent in pediatric CAP. However, in children who fail to respond to guideline directed antibiotic therapy, a non-pneumococcal, possibly one of several β-lactam resistant causative bacterial agents should be considered thus clarifying the advantage for broad-spectrum empirical antibiotic treatment in this group of patients.

Interleukin-23 (IL-23) deficiency disrupts Th17 and Th1-related defenses against Streptococcus pneumoniae infection

Resolution of acute of infection caused by capsular Streptococcus pneumoniae infection in the absence of effective antibiotic therapy requires tight regulation of immune and inflammatory responses. To provide new mechanistic insight of the requirements needed for innate host defenses against acute S. pneumoniae infection, we examined how IL-23 deficiency mediated acute pulmonary resistance. We found that IL-23 deficient mice were more susceptible to bacterial colonization in the lungs corresponding with greater bacterial dissemination. The lack of IL-23 was found to decrease IL-6 and IL-12p70 cytokine levels in bronchiolar lavage within the initial day after infection. Pulmonary leukocytes isolated from infected IL-23 deficient mice demonstrated a dramatic decrease in IL-17A and IFN-γ in response to heat-killed organisms. These findings corresponded with significant abrogation of neutrophilic infiltrate in the lungs compared to IL-23 competent mice. Whereas previous studies have shown opposing influences of IL-12/IL-23 regulation, our findings suggest a concordant dependency of IL-23 expression on Th1 and Th17-related responses.

Antibiotics for community-acquired pneumonia in children

BACKGROUND

Pneumonia caused by bacterial pathogens is the leading cause of mortality in children in low-income countries. Early administration of antibiotics improves outcomes.

OBJECTIVES

To identify effective antibiotic drug therapies for community-acquired pneumonia (CAP) of varying severity in children by comparing various antibiotics.

SEARCH METHODS

We searched CENTRAL 2012, Issue 10; MEDLINE (1966 to October week 4, 2012); EMBASE (1990 to November 2012); CINAHL (2009 to November 2012); Web of Science (2009 to November 2012) and LILACS (2009 to November 2012).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in children of either sex, comparing at least two antibiotics for CAP within hospital or ambulatory (outpatient) settings.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from the full articles of selected studies.

MAIN RESULTS

We included 29 trials, which enrolled 14,188 children, comparing multiple antibiotics. None compared antibiotics with placebo.Assessment of quality of study revealed that 5 out of 29 studies were double-blind and allocation concealment was adequate. Another 12 studies were unblinded but had adequate allocation concealment, classifying them as good quality studies. There was more than one study comparing co-trimoxazole with amoxycillin, oral amoxycillin with injectable penicillin/ampicillin and chloramphenicol with ampicillin/penicillin and studies were of good quality, suggesting the evidence for these comparisons was of high quality compared to other comparisons.In ambulatory settings, for treatment of World Health Organization (WHO) defined non-severe CAP, amoxycillin compared with co-trimoxazole had similar failure rates (odds ratio (OR) 1.18, 95% confidence interval (CI) 0.91 to 1.51) and cure rates (OR 1.03, 95% CI 0.56 to 1.89). Three studies involved 3952 children.In children with severe pneumonia without hypoxaemia, oral antibiotics (amoxycillin/co-trimoxazole) compared with injectable penicillin had similar failure rates (OR 0.84, 95% CI 0.56 to 1.24), hospitalisation rates (OR 1.13, 95% CI 0.38 to 3.34) and relapse rates (OR 1.28, 95% CI 0.34 to 4.82). Six studies involved 4331 children below 18 years of age.In very severe CAP, death rates were higher in children receiving chloramphenicol compared to those receiving penicillin/ampicillin plus gentamicin (OR 1.25, 95% CI 0.76 to 2.07). One study involved 1116 children.

AUTHORS' CONCLUSIONS

For treatment of patients with CAP in ambulatory settings, amoxycillin is an alternative to co-trimoxazole. With limited data on other antibiotics, co-amoxyclavulanic acid and cefpodoxime may be alternative second-line drugs. Children with severe pneumonia without hypoxaemia can be treated with oral amoxycillin in an ambulatory setting. For children hospitalised with severe and very severe CAP, penicillin/ampicillin plus gentamycin is superior to chloramphenicol. The other alternative drugs for such patients are co-amoxyclavulanic acid and cefuroxime. Until more studies are available, these can be used as second-line therapies.There is a need for more studies with radiographically confirmed pneumonia in larger patient populations and similar methodologies to compare newer antibiotics. Recommendations in this review are applicable to countries with high case fatalities due to pneumonia in children without underlying morbidities and where point of care tests for identification of aetiological agents for pneumonia are not available.

Glycopeptide resistance in gram-positive cocci: a review

Vancomycin-resistant enterococci (VRE) have emerged as important nosocomial pathogens in the past two decades all over the world and have seriously limited the choices available to clinicians for treating infections caused by these agents. Methicillin-resistant Staphylococcus aureus, perhaps the most notorious among the nosocomial pathogens, was till recently susceptible to vancomycin and the other glycopeptides. Emergence of vancomycin nonsusceptible strains of S. aureus has led to a worrisome scenario where the options available for treating serious infections due to these organisms are very limited and not well evaluated. Vancomycin resistance in clinically significant isolates of coagulase-negative staphylococci is also on the rise in many setups. This paper aims to highlight the genetic basis of vancomycin resistance in Enterococcus species and S. aureus. It also focuses on important considerations in detection of vancomycin resistance in these gram-positive bacteria. The problem of glycopeptide resistance in clinical isolates of coagulase-negative staphylococci and the phenomenon of vancomycin tolerance seen in some strains of Streptococcus pneumoniae has also been discussed. Finally, therapeutic options available and being developed against these pathogens have also found a mention.

High prevalence of dihydropteroate synthase mutations in Pneumocystis jirovecii isolated from patients with Pneumocystis pneumonia in South Africa

Pneumocystis jirovecii pneumonia (PCP) is an important cause of morbidity and mortality in immunocompromised patients. Sulfa-containing drugs are used for the treatment and prophylaxis of PCP. Mutations in the P. jirovecii fas gene, which encodes dihydropteroate synthase (DHPS), are associated with prior exposure to sulfa drugs, and their appearance suggests the emergence of variants with reduced sulfa susceptibility. The present study examined the prevalence of DHPS mutations in P. jirovecii strains isolated from South African patients with PCP. P. jirovecii infection was investigated by immunofluorescence microscopy and quantitative real-time PCR with respiratory specimens from 712 patients (93% of whom were >15 years of age) with suspected PCP consecutively received for the detection of P. jirovecii over 1 year. PCR amplification and sequencing of the DHPS fas gene was attempted with DNA from the P. jirovecii-positive samples. P. jirovecii infection was confirmed by immunofluorescence microscopy in 168/712 (24%) of the patients. Carriage of the fungus was revealed by real-time PCR in 17% of the patients with negative microscopy results. The P. jirovecii fas gene was successfully amplified from specimens from 151 patients and sequenced. Mutations resulting in the Thr55Ala and/or Pro57Ser amino acid substitution were detected in P. jirovecii strains from 85/151 (56%) patients. The high frequency of PCP episodes with P. jirovecii harboring DHPS mutations in South Africa indicates that populations of this fungus are evolving under the considerable selective pressure exerted by sulfa-containing antibiotics. These results, similar to previous observations of sulfa drug resistance in bacterial populations, underscore the importance of the rational use of sulfa medications either prophylactically against PCP or for the treatment of other infections.

Antibiotics for community-acquired pneumonia in children

BACKGROUND

Pneumonia caused by bacterial pathogens is the leading cause of mortality in children in low-income countries. Early administration of antibiotics improves outcomes.

OBJECTIVES

To identify effective antibiotics for community acquired pneumonia (CAP) in children by comparing various antibiotics.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2) which contains the Cochrane Acute Respiratory Infections Group's Specialised Register; MEDLINE (1966 to September 2009); and EMBASE (1990 to September 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in children of either sex, comparing at least two antibiotics for CAP within hospital or ambulatory (outpatient) settings.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data from full articles of selected studies.

MAIN RESULTS

There were 27 studies, which enroled 11,928 children, comparing multiple antibiotics. None compared antibiotic with placebo.For ambulatory treatment of non-severe CAP, amoxycillin compared with co-trimoxazole had similar failure rates (OR 0.92; 95% CI 0.58 to 1.47) and cure rates (OR 1.12; 95% CI 0.61 to 2.03). (Three studies involved 3952 children).In children hospitalised with severe CAP, oral amoxycillin compared with injectable penicillin or ampicillin had similar failure rates (OR 0.95; 95% CI 0.78 to 1.15). (Three studies involved 3942 children). Relapse rates were similar in the two groups (OR 1.28; 95% CI 0.34 to 4.82).In very severe CAP, death rates were higher in children receiving chloramphenicol compared to those receiving penicillin/ampicillin plus gentamycin (OR 1.25; 95% CI 0.76 to 2.07). (One study involved 1116 children).

AUTHORS' CONCLUSIONS

There were many studies with different methodologies investigating multiple antibiotics. For treatment of ambulatory patients with CAP, amoxycillin is an alternative to co-trimoxazole. With limited data on other antibiotics, co-amoxyclavulanic acid and cefpodoxime may be alternative second-line drugs. For severe pneumonia without hypoxia, oral amoxycillin may be an alternative to injectable penicillin in hospitalised children; however, for ambulatory treatment of such patients with oral antibiotics, more studies in community settings are required. For children hospitalised with severe and very severe CAP, penicillin/ampicillin plus gentamycin is superior to chloramphenicol. The other alternative drugs for such patients are ceftrioxone, levofloxacin, co-amoxyclavulanic acid and cefuroxime. Until more studies are available, these can be used as a second-line therapy.There is a need for more studies with larger patient populations and similar methodologies to compare newer antibiotics.

Identification of Streptococcus pneumoniae genes specifically induced in mouse lung tissues

To identify Streptococcus pneumoniae genes expressed specifically during infections, a selection system based on the in vivo expression technology (IVET) was established. galU, which is critical for capsular polysaccharide biosynthesis, and lacZY encoding beta-galactosidase were employed as dual reporter genes to screen in-vivo-induced (ivi) genes of S. pneumoniae. The galU-deficient mutant of S. pneumoniae is incapable of utilizing galactose, thus failing to synthesize capsular polysaccharide, and therefore loses its ability to survive in the host. A promoter-trap library was constructed in S. pneumoniae, which was used to infect BALB/c mice in an intranostril model. Those strains recovered from lung tissue of mice and exhibiting a white colony phenotype on tryptic soy agar containing X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside) were collected and identificated. A total of 15 unique sequences were obtained through in vivo screening. The ivi genes of S. pneumoniae are involved in many processes, such as colonization and adherence, energy metabolism, nutrient substance transport, transcription regulation, DNA metabolism, and cell wall synthesis. There are some hypothetical proteins whose functions are not clear. This novel IVET is a useful tool for identifying ivi genes in S. pneumoniae.

Pneumococcal antimicrobial resistance: therapeutic strategy and management in community-acquired pneumonia

Streptococcus pneumoniae has been consistently shown to represent the most frequent causative agent of community-acquired pneumonia (CAP) and pneumococcal antibiotic resistance towards different families of antibiotics continues to be a much-debated issue. Microbial resistance causes a great deal of confusion in choosing an empirical treatment for pneumonia and this makes it necessary to know which factors actually determine the real impact of antimicrobial resistance on the outcome of pneumococcal infections. Several different aspects have to be taken into account when analyzing this matter, such as the study design, the condition of the patient at the time of diagnosis, the choice of the initial antimicrobial regimen (combination or monotherapy) and the pharmacokinetic/pharmacodynamic variables of the chosen antibiotic. It is generally accepted that in the treatment of beta-lactam-resistant pneumococcal infections, the use of standard antipneumococcal beta-lactam agents is unlikely to impact negatively on the outcome of CAP when appropriate agents are given in sufficient doses. As a general rule, for infections with penicillin-sensitive strains, penicillin or an aminopenicillin in a standard dosage will be effective; in the cases of strains with intermediate resistance, beta-lactam agents are still considered appropriate treatment although higher dosages are recommended; finally, infections with isolates of high-level penicillin resistance should be treated with alternative agents such as the third-generation cephalosporins or the new antipneumococcal fluoroquinolones. In areas of high prevalence of high-level macrolide resistance, empirical monotherapy with a macrolide is not optimal for the treatment of hospitalised patients with moderate or moderately-severe CAP. Fluoroquinolones are considered to be excellent antibiotics in the treatment of pneumococcal CAP in adults, but their general recommendation has been withheld due to fears of a widespread development of resistance. Most international guidelines recommend combination therapy (beta-lactam plus a macrolide) for the treatment of hospitalised patients with CAP.

Antibiotics for community acquired pneumonia in children

BACKGROUND

Pneumonia is the leading cause of mortality in children. In developing countries, pneumonia is usually caused by bacterial pathogens. The early administration of empirical antibiotics improves the patients' clinical outcomes. There are currently no systematic reviews of clinical trials on this subject.

OBJECTIVES

To identify effective antibiotic drug therapy for community acquired pneumonia (CAP) in children by comparing various antibiotics.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 4, 2005), MEDLINE (OVID) (1966 to January 2006) and EMBASE (WebSPIRS) (1990 to September 2005). There were no language restrictions.

SELECTION CRITERIA

Randomized controlled trials (RCTs) in children of either sex, which compared at least two antibiotics for CAP in hospital or ambulatory settings.

DATA COLLECTION AND ANALYSIS

Data from full articles of selected studies were independently extracted by two authors.

MAIN RESULTS

The review of these studies suggests that for treatment of pneumonia, co-trimoxazole is inferior in efficacy to both amoxycillin (failure rates odds ratio (OR) 1.33; 95% CI 1.05 to 1.67) and procaine penicillin (cure rates OR 2.64; 95% CI 1.57 to 4.45). Penicillin in conjunction with gentamycin was better than chloramphenicol alone (re-hospitalization rates OR 1.61; 95% CI 1.02 to 2.55). Co-amoxyclavulanic acid was better than amoxycillin alone (cure rates OR 10.44; 95% CI 2.85 to 38.21). There was no differences between injectable penicillin and oral amoxycillin (failure rates OR 1.03; 95% CI 0.81 to 1.31); azithromycin and erythromycin (cure rates OR 1.17; 95% CI 0.70 to 1.95); cefpodoxime and amoxycillin (cure rates OR 0.69; 95% CI 0.18 to 2.60); or azithromycin and co-amoxyclavulanic acid (cure rates OR 1.02; 95% CI 0.54 to 1.95, failure rates OR 1.42; 95% CI 0.43 to 4.66).

AUTHORS' CONCLUSIONS

There were many studies each investigating multiple antibiotics with different methodologies. For treatment of ambulatory patients with CAP, amoxycillin was better than co-trimoxazole; there was no difference between azithromycin and erythromycin, or between cefpodoxime and co-amoxyclavulanic acid. For hospitalized patients, procaine penicillin was better than co-trimoxazole; and the combination of penicillin and gentamycin was better than chloramphenicol alone. Injectable penicillin and oral amoxycillin had similar failure rates. For the rest of the antibiotics there were only single studies available. There is a need for more studies with large patient populations and similar methodologies in order to compare newer antibiotics.

Novel Antibacterial Class: A Series of Tetracyclic Derivatives

We describe the synthesis and antibacterial activity of a series of tetracyclic naphthyridones. The members of this series act primarily via inhibition of bacterial translation and belong to the class of novel ribosome inhibitors (NRIs). In this paper we explore the structure-activity relationships (SAR) of these compounds to measure their ability both to inhibit bacterial translation and also to inhibit the growth of bacterial cells in culture. The most active of these compounds inhibit Streptococcus pneumoniae translation at concentrations of <5 microM and have minimum inhibitory concentrations (MICs) of <8 microg/mL against clinically relevant strains of bacteria.

Efficacy and safety of telithromycin 800 mg once daily for 7 days in community-acquired pneumonia: an open-label, multicenter study

Background

Community-acquired pneumonia (CAP) remains a major cause of morbidity and mortality throughout the world. Telithromycin (a new ketolide) has shown good in vitro activity against the key causative pathogens of CAP, including S pneumoniae resistant to penicillin and/or macrolides.

Methods

The efficacy and safety of telithromycin 800 mg orally once daily for 7 days in the treatment of CAP were assessed in an open-label, multicenter study of 442 adults.

Results

Of 149 microbiologically evaluable patients, 57 (9 bacteremic) had Streptococcus pneumoniae. Of the 57 S pneumoniae pathogens isolated in these patients, 9 (2 bacteremic) were penicillin- or erythromycin-resistant; all 57 were susceptible to telithromycin and were eradicated. Other pathogens and their eradication rates were: Haemophilus influenzae (96%), Moraxella catarrhalis (100%), Staphylococcus aureus (80%), and Legionella spp. (100%). The overall bacteriologic eradication rate was 91.9%. Of the 357 clinically evaluable patients, clinical cure was achieved in 332 (93%). In the 430 patients evaluable for safety, the most common drug-related adverse events were diarrhea (8.1%) and nausea (5.8%).

Conclusion

Telithromycin 800 mg once daily for 7 days is an effective and well-tolerated oral monotherapy and offers a new treatment option for CAP patients, including those with resistant S pneumoniae.

Antibacterial drug resistance: implications for the treatment of patients with community-acquired pneumonia

In contrast to the tremendous number of articles and meetings devoted to elucidating the mechanisms of antibacterial drug resistance and describing the emergence of drug resistance patterns, little research has been completed on the impact of bacterial drug resistance on clinical outcomes. Moreover.among the studies that have been completed, the better-designed studies generally have failed to detect an effect of most current levels of antibacterial drug resistance on clinical outcomes for patients who have CAP. Yet, practice patterns are shifting in response to the perception that current levels of drug resistance necessitate changes in treatment patterns. This is unfortunate because it severely limits one's ability to continue to monitor the effectiveness of available therapies in light of changing patterns of antibacterial drug resistance. If levels of drug resistance continue to rise, it is likely that outcomes from those drug treatments will be affected adversely. In this regard, the recent licensing of a 7-valent pneumococcal conjugate vaccine for infants and young children may have an important effect on future trends in antibacterial drug resistance. The vaccine reduces childhood carriage of vaccine serotypes,which are among the most common serotypes found among drug-resistant isolates, and may reduce transmission of these serotypes to adults [65]. In conclusion, antibacterial drug resistance has not reduced substantially the effectiveness of first-line treatments for CAP. Whether levels of drug resistance will continue to increase or decline is unknown. Therefore,carefully designed outcomes studies likely will continue to be essential to help define optimal therapy for patients who have CAP.

Novel antibacterial class

We report the discovery and characterization of a novel ribosome inhibitor (NRI) class that exhibits selective and broad-spectrum antibacterial activity. Compounds in this class inhibit growth of many gram-positive and gram-negative bacteria, including the common respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis, and are nontoxic to human cell lines. The first NRI was discovered in a high-throughput screen designed to identify inhibitors of cell-free translation in extracts from S. pneumoniae. The chemical structure of the NRI class is related to antibacterial quinolones, but, interestingly, the differences in structure are sufficient to completely alter the biochemical and intracellular mechanisms of action. Expression array studies and analysis of NRI-resistant mutants confirm this difference in intracellular mechanism and provide evidence that the NRIs inhibit bacterial protein synthesis by inhibiting ribosomes. Furthermore, compounds in the NRI series appear to inhibit bacterial ribosomes by a new mechanism, because NRI-resistant strains are not cross-resistant to other ribosome inhibitors, such as macrolides, chloramphenicol, tetracycline, aminoglycosides, or oxazolidinones. The NRIs are a promising new antibacterial class with activity against all major drug-resistant respiratory pathogens.

Positive blood cultures in sickle cell disease: time to positivity and clinical outcome

PURPOSE

To prospectively identify all cases of bacteremia in children with sickle cell disease (SCD), establish time to positivity for various microorganisms, correlate clinical findings with microbiology data, and determine the antibiotic resistance pattern of the pneumococcal isolates.

METHODS

All positive blood cultures from children with SCD followed at the Children's Hospital of Philadelphia from January 1993 through May 2001 were included. Isolates were classified as pathogen or contaminant. Demographic and clinical information was abstracted from the medical records. Time to positivity and antibiotic resistance data were generated in the microbiology laboratory.

RESULTS

One hundred forty-one positive blood culture bottles were obtained during distinct febrile episodes. Thirty-nine percent contained pathogens and 61% contained contaminants. The average time to positivity was 17.1 hours in the pathogen group and 29.5 hours in the contaminant group (P < 0.0001). Streptococcus pneumoniae was the most common pathogen (42% of total), with a mean patient age of 3.5 years. Gram-negative rods were the second most common organism (28% of total), with a mean patient age of 8.1 years. Thirty-one percent of the pneumococcal isolates were resistant to penicillin. Thirty-five percent of the pneumococcal isolates grew from children with a focus of infection. Acute chest syndrome was noted in 26% of patients with a positive blood culture for S. pneumoniae. Sixty-seven percent of Salmonella isolates and 50% of Staphylococcus aureus isolates grew from patients who developed osteomyelitis.

CONCLUSIONS

The average time to positivity for pathogens can be used in conjunction with other factors to determine the length of observation required for children with SCD who present with febrile illness. Chest radiographs should be obtained on children with SCD who are bacteremic with S. pneumoniae. Bone scans should be obtained on children with SCD who are bacteremic with Salmonella or S. aureus.

A controlled, double-blind, multicenter study comparing clarithromycin extended-release tablets and levofloxacin tablets in the treatment of community-acquired pneumonia

BACKGROUND

Macrolides and fluoroquinolones are frequently used for the empiric treatment of community-acquired pneumonia (CAP).

OBJECTIVE

The aim of the study was to compare the safety profile and efficacy of clarithromycin extended-release (ER) tablets with those of levofloxacin tablets for the treatment of CAP in ambulatory adult patients.

METHODS

In a Phase III, double-blind, randomized, parallel-group, multicenter study, ambulatory adult patients (> or = 18 years) with signs and symptoms of CAP received a 7-day course of treatment with either clarithromycin ER (two 500-mg tablets once daily) or levofloxacin (two 250-mg tablets once daily). A diagnosis of CAP was confirmed by radiography of the chest and physical examination, and sputum samples were analyzed to identify etiologic pathogen(s). Tolerability was assessed through subjective reports of adverse events and through changes in physical findings, concomitant medications, and laboratory values.

RESULTS

There were no statistically significant differences between treatment groups in terms of sex, age, race, or body weight. The mean age was 50 years (range, 18-91 years). Of 299 patients randomized and treated, 252 were clinically evaluable (128 clarithromycin ER, 124 levofloxacin). The 95% CI for the difference between cure rates demonstrated equivalence of the 2 treatments. Among clinically evaluable patients at the test-of-cure visit, clinical cure rates were 88% (113/128) and 86% (107/124), and radiographic success rates were 95% (117/123) and 88% (104/118) for clarithromycin ER and levofloxacin, respectively. Both treatment regimens were effective in resolving and improving clinical signs and symptoms of CAP. Among clinically and bacteriologically evaluable pa- tients, bacteriologic cure rates were 86% (80/93) and 88% (85/97) for clarithromycin ER and levofloxacin, respectively. No statistically significant differences were observed between the 2 treatment groups in the overall incidence of adverse events.

CONCLUSIONS

Clarithromycin ER demonstrated equivalent efficacy and tolerability to the fluoroquinolone levofloxacin in a group of ambulatory adult patients with CAP. Clarithromycin ER also appeared to be safe in the population studied.

Acute exacerbation of chronic bronchitis: disease-specific issues that influence the cost-effectiveness of antimicrobial therapy

BACKGROUND

Acute exacerbation of chronic bronchitis (AECB) is a common condition, with substantial associated costs and morbidity. Research efforts have focused on innovations that will reduce the morbidity associated with AECB. Health care payers increasingly expect that the results of evidence-based economic evaluations will guide practitioners in their choice of cost-effective interventions.

OBJECTIVES

To provide a framework on which to base effective and efficient antimicrobial therapy for AECB, we present a concise clinical review of AECB, followed by an assessment of the available data on the economic impact of this disease. We then address several AECB-specific issues that must be considered in cost-effectiveness analyses of AECB antimicrobial interventions.

METHODS

Published literature on the clinical and economic impact of AECB was identified using MEDLINE, pre-MEDLINE, HealthSTAR, CINAHL, Current Contents/All Editions, EMBASE, and International Pharmaceutical Abstracts databases. Other potential sources were identified by searching for references in retrieved articles, review articles, consensus statements, and articles written by selected authorities.

RESULTS

In evaluating cost-effectiveness analyses of AECB antimicrobial therapy it is critical to (1) use the disease-free interval as an outcome measure, (2) evaluate the sequence of multiple therapies, (3) address the impact of both current and future antibiotic resistance, and (4) measure all appropriate AECB-associated costs, both direct and indirect.

CONCLUSIONS

Incorporating these approaches in economic analyses of AECB antimicrobial therapy can help health care organizations make evidence-based decisions regarding the cost-effective management of AECB.

Characteristics of patients with upper respiratory tract infection presenting to a walk-in clinic

OBJECTIVE

To profile patients with upper respiratory tract infection (URI) presenting to a walk-in clinic, to quantify their perspectives on the need for antibiotic therapy, and to find out their predictions of future behavior for similar illnesses.

PATIENTS AND METHODS

In the spring of 1998, previsit and postvisit questionnaires were distributed at the clinic to patients 18 years of age or older with URI symptoms.

RESULTS

Based on 210 completed previsit questionnaires, 161 respondents (77%) had been ill 5 or more days, 200 (95%) had cough, 177 (84%) had phlegm, 132 (63%) had sinus pain, and 79 (38%) had fever. Additionally, 54 patients (26%) reported a history of chronic obstructive pulmonary disease, asthma, or chronic sinusitis, and 37 (18%) were smokers. Most patients were between 18 and 40 years of age. The 210 patients were categorized into 2 groups: those who believed that antibiotics were necessary (157 [75%]) and those who believed antibiotics were unnecessary (53 [25%]). The only statistically significant difference between the 2 groups was in patients with sinus pain: 109 (69%) wanted antibiotics compared with 23 (43%) who did not (P<.001). Of the 210 patients, 130 completed postvisit questionnaires, 129 (99%) of whom reported satisfaction with the clinic visit. All patients who either desired or received antibiotics indicated they would likely seek medical care for future URIs.

CONCLUSIONS

The majority of patients with presumed URI presenting to this walk-in clinic expect to receive treatment with antibiotics. Of our 130 study patients, 83 (64%) received antibiotics regardless of their desire for antibiotic treatment. Satisfaction with the office visit was independent of patients' initial beliefs about antibiotics and whether antibiotics were prescribed.