Penicillins for Treatment of Pneumococcal Pneumonia: Does In Vitro Resistance Really Matter?

Bacterial meningitis in Africa

Bacterial meningitis differs globally, and the incidence and case fatality rates vary by region, country, pathogen, and age group; being a life-threatening disease with a high case fatality rate and long-term complications in low-income countries. Africa has the most significant prevalence of bacterial meningitis illness, and the outbreaks typically vary with the season and the geographic location, with a high incidence in the meningitis belt of the sub-Saharan area from Senegal to Ethiopia. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are the main etiological agents of bacterial meningitis in adults and children above the age of one. Streptococcus agalactiae (group B Streptococcus), Escherichia coli, and Staphylococcus aureus are neonatal meningitis's most common causal agents. Despite efforts to vaccinate against the most common causes of bacterial neuro-infections, bacterial meningitis remains a significant cause of mortality and morbidity in Africa, with children below 5 years bearing the heaviest disease burden. The factors attributed to this continued high disease burden include poor infrastructure, continued war, instability, and difficulty in diagnosis of bacterial neuro-infections leading to delay in treatment and hence high morbidity. Despite having the highest disease burden, there is a paucity of African data on bacterial meningitis. In this article, we discuss the common etiologies of bacterial neuroinfectious diseases, diagnosis and the interplay between microorganisms and the immune system, and the value of neuroimmune changes in diagnostics and therapeutics.

Guía de práctica clínica para el manejo de la neumonía adquirida en la comunidad

La neumonía sigue siendo una de las principales causas de consulta y de hospitalización a la que, además de su un alto impacto en términos de morbilidad y mortalidad, se suma la actual problemática de resistencia a los antimicrobianos, por lo que establecer directrices que permitan su adecuado diagnóstico y tratamiento es de gran importancia para obtener mejores desenlaces clínicos y promover un uso racional de antibióticos en estos pacientes. La presente guía de práctica clínica (GPC) contiene recomendaciones basadas en la evidencia para el diagnóstico y tratamiento de la neumonía adquirida en la comunidad en adultos, las cuales fueron realizadas mediante el proceso de adaptación de GPC basadas en la evidencia para el contexto colombiano.

Predictors and usefulness of targeted therapy for pneumococcal community-acquired pneumonia diagnosed by the urinary antigen test: a prospective, observational cohort study

The aim of the present study was to investigate the predictors of targeted therapy (TT) for pneumococcal community-acquired pneumonia (PCAP) with a positive urinary antigen test (UAT) and compare the outcomes with those of nontargeted therapy. This prospective cohort study enrolled consecutive PCAP patients with a positive UAT who were hospitalized at Kurashiki Central Hospital from October 2010 to November 2019. A total of 286 patients were included. Of them, 56 patients (19.6%) were included in the TT group. On multivariate analysis, identification of Gram-positive diplococci by Gram stain (OR [95% CI]: 2.46 [1.32-4.63]) was a positive predictor, whereas aspiration pneumonia (0.17 [0.03-0.59]) and CURB-65 score (0.59 [0.42-0.81]) were negative predictors of TT. Initial treatment failure and 30-day mortality were not significantly different. The UAT is not used enough for TT, and TT for PCAP did not have worse outcomes.

Improved penicillin susceptibility of Streptococcus pneumoniae and increased penicillin consumption in Japan, 2013-18

OBJECTIVES

To examine the association between penicillin susceptibility of Streptococcus pneumoniae and penicillin consumption in Japan.

METHODS

We used Japan Nosocomial Infection Surveillance data on the susceptibility of S. pneumoniae and sales data obtained from IQVIA Services Japan K.K. for penicillin consumption. We analysed both sets of data by decomposing them into seasonality and chronological trend components. The cross-correlation function was checked using Spearman's rank correlation coefficient to examine the correlation between susceptibility and consumption.

RESULTS

After adjusting for seasonality, the susceptibility of S. pneumoniae to penicillins gradually improved (55.7% in 2013 and 60.6% in 2018, respectively) and penicillin consumption increased during the same period (0.76 defined daily doses per 1,000 inhabitants per day [DID] in 2013, and 0.89 DID in 2018). The results showed positive cross-correlation (coefficient 0.801, p-value < 0.001). In contrast, cephalosporin consumption decreased (3.91 DID in 2013 and 3.19 DID in 2018) and showed negative cross-correlation with susceptibility of S. pneumoniae to penicillins (coefficient -0.981, p-value < 0.001).

CONCLUSIONS

The rates of penicillin-susceptible S. pneumoniae isolates did not negatively correlate with penicillin consumption at the population level. Increased penicillin consumption might not impair the penicillin susceptibility of S. pneumoniae.

Antibacterial mechanism of gold nanoparticles on Streptococcus pneumoniae

Streptococcus pneumoniae is a causal agent of otitis media, pneumonia, meningitis and severe cases of septicemia. This human pathogen infects elderly people and children with a high mortality rate of approximately one million deaths per year worldwide. Antibiotic-resistance of S. pneumoniae strains is an increasingly serious health problem; therefore, new therapies capable of combating pneumococcal infections are indispensable. The application of gold nanoparticles has emerged as an option in the control of bacterial infections; however, the mechanism responsible for bacterial cell lysis remains unclear. Specifically, it has been observed that gold nanoparticles are capable of crossing different structures of the S. pneumoniae cells, reaching the cytosol where inclusion bodies of gold nanoparticles are noticed. In this work, a novel process for the separation of such inclusion bodies that allowed the analysis of the biomolecules such as carbohydrates, lipids and proteins associated with the gold nanoparticles was developed. Then, it was possible to separate and identify proteins associated with the gold nanoparticles, which were suggested as possible candidates that facilitate the interaction and entry of gold nanoparticles into S. pneumoniae cells.

Why is the rate of pneumococcal pneumonia declining?

PURPOSE OF REVIEW

As Streptococcus pneumoniae was considered the etiological agent of nearly all the cases of pneumonia at the beginning of the 20th century, and today is identified in fewer than 10-15% of cases, we analyze the possible causes of such a decline.

RECENT FINDINGS

Extensive use of early empiric antimicrobial therapy, discovery of previously unrecognized pathogens, availability to newer diagnostic methods for the recognition of the pneumonia pathogens (PCR, urinary antigens, monoclonal antibodies etc.) and of improved preventive measures, including vaccines, are some of possible explanations of the declining role of S. pneumoniae in the cause of pneumonia.

SUMMARY

The 14-valent and the 23-valent capsular polysaccharide pneumococcal vaccines were licensed in 1977 and 1983, respectively. The seven-valent protein-conjugated capsular polysaccharide vaccine, approved for routine use in children starting at 2 months of age, was highly effective in preventing invasive pneumococcal disease in children but also in adults because of the herd effect. In 2010, the 13-valent protein-conjugated capsular polysaccharide vaccine replaced seven-valent protein-conjugated capsular polysaccharide vaccine. With the use of conjugated vaccines, a decrease of the vaccine-type invasive pneumococcal disease for all age groups was observed. Both the direct effect of the vaccine and the so-called herd immunity are considered responsible for much of the decline.

Rapid diagnostics for bloodstream infections: A primer for infection preventionists

Accurate and rapid antimicrobial susceptibility testing with pathogen identification in bloodstream infections is critical to life results for early sepsis intervention. Advancements in rapid diagnostics have shortened the time to results from days to hours and have had positive effects on clinical outcomes and on efforts to combat antimicrobial resistance when paired with robust antimicrobial stewardship programs. This article provides infection preventionists with a working knowledge of available rapid diagnostics for bloodstream infections.

Reversion of High-level Mecillinam Resistance to Susceptibility in Escherichia coli During Growth in Urine

Mecillinam (amdinocillin) is a β-lactam antibiotic used to treat uncomplicated urinary tract infections (UTIs). We have previously shown that inactivation of the Escherichia coli cysB gene is the major cause of mecillinam resistance (MecR) in clinical isolates. In this study, we used different E. coli strains (laboratory and clinical isolates) that were MecR due to cysB mutations to determine how mecillinam susceptibility was affected during growth in urine compared to growth in the commonly used growth medium Mueller Hinton (MHB). We also examined mecillinam susceptibility when bacteria were grown in urine obtained from 48 different healthy volunteers. Metabolome analysis was done on the urine samples and the association between the mecillinam susceptibility patterns of the bacteria and urine metabolite levels was studied. Two major findings with clinical significance are reported. First, MecRE. coli cysB mutant strains (both laboratory and clinical isolates) were always more susceptible to mecillinam when grown in urine as compared to laboratory medium, with many strains showing complete phenotypic susceptibility in urine. Second, the degree of reversion to susceptibility varied between urine samples obtained from different individuals. This difference was correlated with osmolality such that in urine with low osmolality the MecR mutants were more susceptible to mecillinam than in urine with high osmolality. This is the first example describing conditional resistance where a genetically stable antibiotic resistance can be phenotypically reverted to susceptibility by metabolites present in urine. These findings have several important clinical implications regarding the use of mecillinam to treat UTIs. First, they suggest that mecillinam can be used to treat also those clinical strains that are identified as MecR in standard laboratory tests. Second, the results suggest that testing of mecillinam susceptibility in the laboratory ought to be performed in media that mimics urine to obtain clinically relevant susceptibility testing results. Third, these findings imply that changes in patient behavior, such as increased water intake or use of diuretics to reduce urine osmolality and increased intake of cysteine, might induce antibiotic susceptibility in an infecting MecRE. coli strain and thereby increase treatment efficiency.

Encouraging rational antibiotic use in childhood pneumonia: a focus on Vietnam and the Western Pacific Region

Globally, pneumonia is considered to be the biggest killer of infants and young children (aged <5 years) outside the neonatal period, with the greatest disease burden in low- and middle-income countries. Optimal management of childhood pneumonia is challenging in settings where clinicians have limited information regarding the local pathogen and drug resistance profiles. This frequently results in unnecessary and poorly targeted antibiotic use. Restricting antibiotic use is a global priority, particularly in Asia and the Western Pacific Region where excessive use is driving high rates of antimicrobial resistance. The authors conducted a comprehensive literature review to explore the antibiotic resistance profile of bacteria associated with pneumonia in the Western Pacific Region, with a focus on Vietnam. Current management practices were also considered, along with the diagnostic dilemmas faced by doctors and other factors that increase unnecessary antibiotic use. This review offers some suggestions on how these issues may be addressed.

High prevalence of antibiotic resistance in nasopharyngeal bacterial isolates from healthy children in rural Uganda: A cross-sectional study

BACKGROUND

In Uganda, the main causes of death in children under 5 years of age are malaria and pneumonia--often due to delayed diagnosis and treatment. In preparation for a community case management intervention for pneumonia and malaria, the bacterial composition of the nasopharyngeal flora and its in vitro resistance were determined in children aged five or under to establish baseline resistance to commonly used antibiotics.

METHODS

In a population-based survey in April 2008, nasopharyngeal specimens were collected from 152 randomly selected healthy children under 5 years of age in the Iganga/Mayuge Health and Demographic Surveillance Site (HDSS). Medical history and prior treatment were recorded. Demographic characteristics and risk factors for carriage of resistant strains were obtained from the HDSS census. Bacteria were isolated and analysed for antibiotic susceptibility using disk diffusion and E test.

RESULTS

Streptococcus pneumoniae (S. pneumoniae) carriage was 58.6%, and, while most (80.9%) isolates had intermediate resistance to penicillin, none was highly resistant. Whereas no isolate was resistant to erythromycin, 98.9% were resistant to trimethoprim-sulphamethoxazole (co-trimoxazole).

CONCLUSIONS

In vitro resistance in S. pneumoniae to co-trimoxazole treatment was high, and the majority of isolates had intermediate resistance to penicillin. To inform treatment policies on the clinical efficacy of current treatment protocols for pneumonia in health facilities and at the community level, routine surveillance of resistance in pneumonia pathogens is needed as well as research on treatment efficacy in cases with resistant strains. Improved clinical algorithms and diagnostics for pneumonia should be developed.

Community-acquired pneumonia: impact of empirical antibiotic therapy without respiratory fluoroquinolones nor third-generation cephalosporins

Guidelines for inpatients with community-acquired pneumonia (CAP) propose to use respiratory fluoroquinolone (RFQ) and/or third-generation cephalosporins (Ceph-3). However, broad-spectrum antibiotic therapy is associated with the emergence of drug-resistant bacteria. We established a guideline in which RFQ and Ceph-3 were excluded as a first course. Our aim was to evaluate the impact of our therapeutic choices for CAP on the length of hospital stay (LOS) and patient outcome. This was a cohort study of patients with CAP from July 2005 to June 2014. We compared patients benefiting from our guideline established in 2008 to those receiving non-consensual antibiotics. Disease severity was evaluated through the Pneumonia Severity Index (PSI). The empirical treatment for PSI III to V was a combination therapy of amoxicillin-clavulanic acid (AMX-C) + roxithromycin (RX) or AMX + ofloxacin. Adherence to guidelines was defined by the prescription of one of these antibiotic agents. Requirement for intensive care or death defined unfavorable outcome. Among 1,370 patients, 847 were treated according to our guideline (61.8 %, group 1) and 523 without concordant therapy (38.2 %, group 2). The mean PSI was similar: 82 vs. 83, p > 0.5. The mean LOS was lower in group 1: 7.6 days vs. 9.1 days, p < 0.001. An unfavorable outcome was less frequent in group 1: 5.4 % vs. 9.9 %, p = 0.001. In logistic regression models, concordant therapy was associated with a favorable outcome: adjusted odds ratio (AOR) [95 % confidence interval (CI)] 1.85 [1.20-2.88], p = 0.005. CAP therapy without RFQ and Ceph-3 use was associated with a shorter LOS and fewer unfavorable outcomes.

Nemonoxacin (TG-873870) for treatment of community-acquired pneumonia

With a broad-spectrum of activity, fluoroquinolones have been widely and successfully used for decades for the treatment of and prophylaxis against various bacterial infections, including community-acquired pneumonia (CAP). However, the use of fluoroquinolones has been compromised by the emergence and spreading of bacterial resistance and the potential for adverse effects. Therefore, there is an unmet need for newer compounds that have a broader spectrum of activity to overcome existing bacterial resistance as well as the potential to minimize the risk of adverse effects. Nemonoxacin (TG-873870), a newly developed quinolone, has demonstrated broad-spectrum activity against Gram-positive, Gram-negative and atypical pathogens, including drug-resistant Streptococcus pneumoniae and methicillin-resistant Staphylococcus aureus. Results from Phases I and II studies of treatment of CAP are encouraging. This article reviews the updated data on nemonoxacin, including the bacterial susceptibility, the pharmacologic characteristics, and toxicities, and clinical trials using nemonoxacin for treatment of CAP.

Antimicrobial resistance trends among community-acquired respiratory tract pathogens in Greece, 2009-2012

The aim of the present study was to determine the antimicrobial resistance trends of respiratory tract pathogens isolated from patients with community-acquired respiratory tract infections (CARTIs) in Crete, Greece, over a 4-year period (2009-2012). A total of 588 community-acquired respiratory pathogens were isolated during the study period. Streptococcus pneumoniae was the most common organism responsible for 44.4% of CARTIs, followed by Haemophilus influenzae (44.2%) and Moraxella catarrhalis (11.4%). Among S. pneumoniae, the prevalence of isolates with intermediate- and high-level resistance to penicillin was 27.2% and 12.3%, respectively. Macrolide resistance slightly decreased from 29.4% over the period 2009-2010 to 28.8% over the period 2011-2012. Multiresistance was observed among 56 (54.4%) penicillin nonsusceptible isolates. A nonsignificant increase in resistance of H. influenzae isolates was noted for β -lactams, cotrimoxazole, and tetracycline. Among the 67 M. catarrhalis tested, 32 produced beta-lactamase and were resistant to ampicillin. Macrolide resistance decreased over the study period. All isolates were susceptible to amoxicillin + clavulanic acid, chloramphenicol, rifampicin, and the fluoroquinolones. Although a decreasing trend in the prevalence of resistance of the three most common pathogens involved in CARTIs was noted, continuous surveillance of antimicrobial susceptibility at the local and national level remains important, in order to guide appropriate empirical antimicrobial therapy.

Overview of community-acquired pneumonia and the role of inflammatory mechanisms in the immunopathogenesis of severe pneumococcal disease

Community-acquired pneumonia (CAP) remains a leading cause of morbidity and mortality among the infectious diseases. Despite the implementation of national pneumococcal polyvalent vaccine-based immunisation strategies targeted at high-risk groups, Streptococcus pneumoniae (the pneumococcus) remains the most common cause of CAP. Notwithstanding the HIV pandemic, major challenges confronting the control of CAP include the range of bacterial and viral pathogens causing this condition, the ever-increasing problem of antibiotic resistance worldwide, and increased vulnerability associated with steadily aging populations in developed countries. These and other risk factors, as well as diagnostic strategies, are covered in the first section of this review. Thereafter, the review is focused on the pneumococcus, specifically the major virulence factors of this microbial pathogen and their role in triggering overexuberant inflammatory responses which contribute to the immunopathogenesis of invasive disease. The final section of the review is devoted to a consideration of pharmacological, anti-inflammatory strategies with adjunctive potential in the antimicrobial chemotherapy of CAP. This is focused on macrolides, corticosteroids, and statins with respect to their modes of anti-inflammatory action, current status, and limitations.

What is the relevance of antimicrobial resistance on the outcome of community-acquired pneumonia caused by Streptococcus pneumoniae? (should macrolide monotherapy be used for mild pneumonia?)

Multidrug-resistant pneumococci continue to increase worldwide. Although there are still questions regarding the relevance of β-lactam resistance, the recommendation for the use of the macrolides as monotherapy for mild community-acquired pneumonia should be revisited in view of high rates of resistance, the association of clinical failures with low-level and high-level resistance, and the lack of clinical data to support their need for empirical therapy for the atypicals.

Current treatment of community-acquired pneumonia

INTRODUCTION

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide. Management decisions regarding site of care, extent of assessment and level of treatment are based primarily on disease severity (outpatient, inpatient and ICU admission). Despite the developments in antibiotic therapy, CAP is still the most common infectious cause of death.

AREAS COVERED

There are several challenges with the management of CAP, from the accurate diagnosis, decisions about place of therapy and the choice of appropriate antibiotics. An extensive literature review of manuscripts, in PubMed, published in the past 10 years has been performed, using combinations of words and terms appropriate to the concepts of CAP, treatment, guidelines and corticoids. Some empirical antimicrobial regimens, such as macrolides, are still being debated; some new antibiotics and adjunctive therapies (corticoids) have recently been tested. This is a review of current recommended antimicrobials regimens, novel approaches and adjunctive drugs for the treatment of CAP.

EXPERT OPINION

Effective management of CAP requires risk stratification of patients by severity and proper place of therapy. Additional therapeutic interventions along with antibiotics may help to improve outcome in patients with CAP, especially in severe CAP.

Antibiotic treatment of children with community-acquired pneumonia: comparison of penicillin or ampicillin versus cefuroxime

OBJECTIVE

Adherence to current guidelines for treatment of non-complicated community-acquired pneumonia (CAP) in children, recommending penicillin or ampicillin as first-line treatment, has been poor. Our objective was to examine whether cefuroxime confers an advantage over penicillin or ampicillin for the treatment of children hospitalized with non-complicated CAP.

PATIENTS AND METHODS

All children aged 3 months to 2 years with non-complicated CAP treated with penicillin or ampicillin or cefuroxime, admitted during 2003-2008, in the Departments of Pediatrics, Hadassah University Medical Center were included. Presenting signs, symptoms, laboratory findings at presentation, clinical parameters including number of days with IV antibiotics, oxygen treatment, length of hospital stay, change of antibiotics, and clinical course 72 hr and 1 week after admission, were compared.

RESULTS

Of the 319 children admitted for non-complicated CAP, 66 were treated with IV penicillin or ampicillin, 253 with IV cefuroxime. Number of days of IV treatment, days of oxygen requirement, and days of hospitalization were similar (2.36 ± 1.6 days vs. 2.59 ± 1.6 days, 0.31 ± 1.2 days vs. 0.64 ± 1.3 days, and 2.67 ± 1.4 days vs. 2.96 ± 1.7 days, respectively). Treatment failure was not significantly different (7.6% vs. 4.7%). The number of patients who were febrile or required oxygen 72 hr after admission was similar (13.0% vs. 16.5% and 8.7% vs. 20.9%, respectively). One week after admission no difference between the two groups was seen.

CONCLUSIONS

In previously healthy children, parenteral penicillin or ampicillin for treatment of non-complicated CAP in-hospital is as effective as cefuroxime, and should remain the recommended first-line therapy.

Guidelines for the management of adult lower respiratory tract infections--summary

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Guidelines for the management of adult lower respiratory tract infections--full version

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Impact of new Clinical Laboratory Standards Institute Streptococcus pneumoniae penicillin susceptibility testing breakpoints on reported resistance changes over time

The analysis comprised a total of 97,843 U.S. isolates from the Surveillance Network(®) database for the period 1996-2008. Penicillin resistance, when defined using the old Clinical Laboratory Standards Institute breakpoint (≥2 μg/ml), had an initial rise that started in 1996, peaked in 2000, declined until 2003, and rebounded through 2008 (15.6%, 23.2%, 15.4%, and 16.9%, respectively). Using the new Clinical Laboratory Standards Institute criteria and applying a breakpoint of ≥8 μg/ml to blood and bronchial isolates, resistance was unchanged (0.24% in 2003) but rose to 1.52% in 2008. Using the new meningitis criteria (≥0.12 μg/ml), resistance prevalence was 34.8% in 2008, whereas it was 12.3% using the old criteria (≥2 μg/ml) for cerebrospinal fluid isolates. The rise, fall, and subsequent rebound of penicillin resistance in the United States, presumably influenced by the introduction of the conjugate pneumococcal vaccine, is clearly seen with the old definition, but only the rebound is seen when the new criteria are applied. In the postvaccine period, isolates with minimum inhibitory concentrations of 1 and 2 μg/ml decline, whereas those with minimum inhibitory concentrations of 0.12-0.5 increase, which may signal the loss of resistant vaccine serotypes and the acquisition of resistance by nonvaccine serotypes.

Newer developments in the treatment of Gram-positive infections

Gram-positive organisms are continually a major cause of infection. These organisms are ever-evolving and exhibit resistance to nearly all available agents. Historically, vancomycin was crowned the drug of choice for many of these organisms including methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae, and penicillin-resistant Enterococcus spp. Many of these organisms have exhibited reduced susceptibility or frank resistance to vancomycin which has resulted in treatment failure. For this reason, new strategies in treating Gram-positive infections are a hot topic. There are two general approaches to waging this war: i) development of new antimicrobial agents; and ii) reinvigorating old antibiotics that still retain appreciable activity against Gram-positives. We review both antibiotic groupings with a focus on S. aureus, S. pneumoniae and Enterococcus spp.

Differentiation of bacterial and non-bacterial community-acquired pneumonia by thin-section computed tomography

Background and objective

The management of community-acquired pneumonia (CAP) depends, in part, on the identification of the causative agents. The objective of this study was to determine the potential of thin-section computed tomography (CT) in differentiating bacterial and non-bacterial pneumonia.

Patients and methods

Thin-section CT studies were prospectively examined in hospitalized CAP patients within 2 days of admission, followed by retrospective assessment by two pulmonary radiologists. Thin-section CT findings on the pneumonias caused by each pathogen were examined, and two types of pneumonias were compared. Using multivariate logistic regression analyses, receiver operating characteristic (ROC) curves were produced.

Results

Among 183 CAP episodes (181 patients, 125 men and 56 women, mean age ± S.D.: 61.1 ± 19.7) examined by thin-section CT, the etiologies of 125 were confirmed (94 bacterial pneumonia and 31 non-bacterial pneumonia). Centrilobular nodules were specific for non-bacterial pneumonia and airspace nodules were specific for bacterial pneumonia (specificities of 89% and 94%, respectively) when located in the outer lung areas. When centrilobular nodules were the principal finding, they were specific but lacked sensitivity for non-bacterial pneumonia (specificity 98% and sensitivity 23%). To distinguish the two types of pneumonias, centrilobular nodules, airspace nodules and lobular shadows were found to be important by multivariate analyses. ROC curve analysis discriminated bacterial pneumonia from non-bacterial pneumonia among patients without underlying lung diseases, yielding an optimal point with sensitivity and specificity of 86% and 79%, respectively, but was less effective when all patients were analyzed together (70% and 84%, respectively).

Conclusion

Thin-section CT examination was applied for the differentiation of bacterial and non-bacterial pneumonias. Though showing some potential, this examination at the present time would not be applicable for patients with underlying lung diseases, severe conditions of pneumonia, or immunocompromised conditions.

Early diagnosis of lower respiratory tract infections (point-of-care tests)

PURPOSE OF REVIEW

Respiratory tract infections are a common reason for prescribing antibiotics, although not all of these infections require such therapy. Rapid diagnosis of etiology using point-of-care tests is a potentially useful way of reducing prescriptions of both unnecessary and unnecessarily broad-spectrum antibiotics. This can also lead to the facilitation of appropriate infection control measures to prevent spread of respiratory viruses within institutions.

RECENT FINDINGS

Point-of-care tests are available for diagnosing influenza, respiratory syncytial virus, Streptococcus pneumoniae, and Legionella infections using easily obtainable specimens. Their main benefit is that results can be obtained in about 15 min with reasonable accuracy. In many situations, however, it is still important to confirm diagnosis with more accurate but slower tests such as bacterial cultures with antibacterial susceptibility testing or viral polymerase chain reaction testing.

SUMMARY

Although the sensitivities of many of the rapid diagnostic tests are moderate, when used at the time of initial consultation, they have the potential to reduce costs, length of stay, secondary spread of respiratory viruses, and inappropriate antibiotic prescribing.

Epidemiology of invasive pneumococcal disease in BC during the introduction of conjugated pneumococcal vaccine

OBJECTIVES

Antimicrobial resistance in Streptococcus pneumoniae has increased in recent decades. We linked two surveillance programs to evaluate trends in incidence, serotype distribution, and antimicrobial resistance in invasive pneumococcal disease (IPD) since the heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in BC in 2003.

METHODS

IPD case reports for BC from 2002-2005 from the BC Centre for Disease Control were linked to serotype and antimicrobial susceptibility results from the National Centre for Streptococcus (NCS).

RESULTS

There was a significant decrease in IPD incidence in children <5 from 54/100,000 in 2002 to 16/100,000 population in 2005 (70% decrease, p < 0.001). The most dramatic decline was in children aged 1 year, where the rate fell from 135/100,000 to 15/100,000 (89% decrease, p for trend <0.001). Overall, 728/1288 (56.5%) reported cases of IPD were referred to NCS. For all matched cases, the proportion of isolates of PCV7 preventable serotypes decreased from 68.9% to 43.8% (p for trend <0.001) between 2002 and 2005. In children <2 years, this proportion decreased from 83.0% (39/47 cases) to 16.7% (1/6 cases) (p = 0.006). The prevalence of non-susceptible isolates was highest for trimethoprim-sulfamethoxazole (15.3%, 111/725 tested), penicillin (9.1%, 66/728), and erythromycin (9.1%, 66/727). 10.3% (75/728) were non-susceptible to > or =2 classes of antimicrobials. Children <15 years of age had the highest proportion of non-susceptible isolates.

DISCUSSION

The incidence of IPD in children has decreased significantly since the introduction of PCV7. Comprehensive serotype and antimicrobial susceptibility can aid in evaluating the impact of immunization programs.

The etiology of community-acquired pneumonia in Australia: why penicillin plus doxycycline or a macrolide is the most appropriate therapy

BACKGROUND

Available data on the etiology of community-acquired pneumonia (CAP) in Australia are very limited. Local treatment guidelines promote the use of combination therapy with agents such as penicillin or amoxycillin combined with either doxycycline or a macrolide.

METHODS

The Australian CAP Study (ACAPS) was a prospective, multicenter study of 885 episodes of CAP in which all patients underwent detailed assessment for bacterial and viral pathogens (cultures, urinary antigen testing, serological methods, and polymerase chain reaction). Antibiotic agents and relevant clinical outcomes were recorded.

RESULTS

The etiology was identified in 404 (45.6%) of 885 episodes, with the most frequent causes being Streptococcus pneumoniae (14%), Mycoplasma pneumoniae (9%), and respiratory viruses (15%; influenza, picornavirus, respiratory syncytial virus, parainfluenza virus, and adenovirus). Antibiotic-resistant pathogens were rare: only 5.4% of patients had an infection for which therapy with penicillin plus doxycycline would potentially fail. Concordance with local antibiotic recommendations was high (82.4%), with the most commonly prescribed regimens being a penicillin plus either doxycycline or a macrolide (55.8%) or ceftriaxone plus either doxycycline or a macrolide (36.8%). The 30-day mortality rate was 5.6% (50 of 885 episodes), and mechanical ventilation or vasopressor support were required in 94 episodes (10.6%). Outcomes were not compromised by receipt of narrower-spectrum beta-lactams, and they did not differ on the basis of whether a pathogen was identified.

CONCLUSIONS

The vast majority of patients with CAP can be treated successfully with narrow-spectrum beta-lactam treatment, such as penicillin combined with doxycycline or a macrolide. Greater use of such therapy could potentially reduce the emergence of antibiotic resistance among common bacterial pathogens.

[Summary of the GEIPC-SEIMC and GTEI-SEMICYUC recommendations for the treatment of infections caused by gram positive cocci in critical patients]

OBJECTIVE

In recent years there has been an increase in infections caused by gram-positive cocci in critical patients, together with a rapid development of resistance to the antibiotics which are normally used to treat them. The objective is to prepare an antibiotic treatment guide for the most common infections caused by gram positive cocci in critical patients. This guide will help in the decision-making process regarding the care of such patients.

METHOD

Experts from two scientific societies worked together to prepare a consensus document. They were members of the Study Group on Infections in Critical Patients (GEIPC), which is part of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), and the Infectious Diseases Working Group (GTEI), belonging to the Spanish Society of Intensive Care Medicine and Coronary Units (SEMICYUC). There was a systematic review of the literature published up to September 2006 regarding this type of infections and the antibiotic treatments marketed to that date. An evidence grading system was applied according to the strength of the recommendation (categories A, B or C) and the level of evidence (categories I, II or III). Recommendations were given if there was consensus among the experts from both societies.

RESULTS

The antibiotic regimens recommended for treating infections caused by gram-positive cocci were presented in the form of tables, showing the recommendation grade. Alternatives were given for allergic patients. The scientific basis supporting the aforementioned recommendations is explained within the text and the references upon which they are based are cited.

CONCLUSIONS

A summary of an evidence-based practical guide for the treatment of infections caused by gram-positive cocci in critical patients is presented.

Clonal spread of highly beta-lactam-resistant Streptococcus pneumoniae isolates in Taiwan

This study aimed to evaluate the antimicrobial susceptibility profiles of 364 Streptococcus pneumoniae isolates and studied the genotypes of S. pneumoniae with high level beta-lactam resistance in Taiwan. Clonal complexes related to Spain(23F)-1, Taiwan(19F)-14, and Taiwan(23F)-15 were responsible for the spread of isolates with high beta-lactam resistance.

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.

Multidrug-resistant Streptococcus pneumoniae infections: current and future therapeutic options

Antibacterial resistance in Streptococcus pneumoniae is increasing worldwide, affecting principally beta-lactams and macrolides (prevalence ranging between approximately 1% and 90% depending on the geographical area). Fluoroquinolone resistance has also started to emerge in countries with high level of antibacterial resistance and consumption. Of more concern, 40% of pneumococci display multi-drug resistant phenotypes, again with highly variable prevalence among countries. Infections caused by resistant pneumococci can still be treated using first-line antibacterials (beta-lactams), provided the dosage is optimised to cover less susceptible strains. Macrolides can no longer be used as monotherapy, but are combined with beta-lactams to cover intracellular bacteria. Ketolides could be an alternative, but toxicity issues have recently restricted the use of telithromycin in the US. The so-called respiratory fluoroquinolones offer the advantages of easy administration and a spectrum covering extracellular and intracellular pathogens. However, their broad spectrum raises questions regarding the global risk of resistance selection and their safety profile is far from optimal for wide use in the community. For multi-drug resistant pneumococci, ketolides and fluoroquinolones could be considered. A large number of drugs with activity against these multi-drug resistant strains (cephalosporins, carbapenems, glycopeptides, lipopeptides, ketolides, lincosamides, oxazolidinones, glycylcyclines, quinolones, deformylase inhibitors) are currently in development. Most of them are only new derivatives in existing classes, with improved intrinsic activity or lower susceptibility to resistance mechanisms. Except for the new fluoroquinolones, these agents are also primarily targeted towards methicillin-resistant Staphylococcus aureus infections; therefore, demonstration of their clinical efficacy in the management of pneumococcal infections is still awaited.

Trends in antibacterial resistance among Streptococcus pneumoniae isolated in the USA: update from PROTEKT US Years 1-4

Background

The increasing prevalence of resistance to established antibiotics among key bacterial respiratory tract pathogens, such as Streptococcus pneumoniae, is a major healthcare problem in the USA. The PROTEKT US study is a longitudinal surveillance study designed to monitor the susceptibility of key respiratory tract pathogens in the USA to a range of commonly used antimicrobials. Here, we assess the geographic and temporal trends in antibacterial resistance of S. pneumoniae isolates from patients with community-acquired respiratory tract infections collected between Year 1 (2000–2001) and Year 4 (2003–2004) of PROTEKT US.

Methods

Antibacterial minimum inhibitory concentrations were determined centrally using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method; susceptibility was defined according to CLSI interpretive criteria. Macrolide resistance genotypes were determined by polymerase chain reaction.

Results

A total of 39,495 S. pneumoniae isolates were collected during 2000–2004. The percentage of isolates resistant to erythromycin, penicillin, levofloxacin, and telithromycin were 29.3%, 21.2%, 0.9%, and 0.02%, respectively, over the 4 years, with marked regional variability. The proportion of isolates exhibiting multidrug resistance (includes isolates known as penicillin-resistant S. pneumoniae and isolates resistant to ≥ 2 of the following antibiotics: penicillin; second-generation cephalosporins, e.g. cefuroxime; macrolides; tetracyclines; and trimethoprim-sulfamethoxazole) remained stable at ~30% over the study period. Overall mef(A) was the most common macrolide resistance mechanism. The proportion of mef(A) isolates decreased from 68.8% to 62.3% between Year 1 and Year 4, while the percentage of isolates carrying both erm(B) and mef(A) increased from 9.7% to 18.4%. Over 99% of the erm(B)+mef(A)-positive isolates collected over Years 1–4 exhibited multidrug resistance. Higher than previously reported levels of macrolide resistance were found for mef(A)-positive isolates.

Conclusion

Over the first 4 years of PROTEKT US, penicillin and erythromycin resistance among pneumococcal isolates has remained high. Although macrolide resistance rates have stabilized, the prevalence of clonal isolates, with a combined erm(B) and mef(A) genotype together with high-level macrolide and multidrug resistance, is increasing, and their spread may have serious health implications. Telithromycin and levofloxacin both showed potent in vitro activity against S. pneumoniae isolates irrespective of macrolide resistance genotype.

[GEIPC-SEIMC (Study Group for Infections in the Critically Ill Patient of the Spanish Society for Infectious Diseases and Clinical Microbiology) and GTEI-SEMICYUC ( Working Group on Infectious Diseases of the Spanish Society of Intensive Medicine, Critical Care, and Coronary Units) recommendations for antibiotic treatment of gram-positive cocci infections in the critical patient]

In recent years, an increment of infections caused by gram-positive cocci has been documented in nosocomial and hospital-acquired-infections. In diverse countries, a rapid development of resistance to common antibiotics against gram-positive cocci has been observed. This situation is exceptional in Spain but our country might be affected in the near future. New antimicrobials active against these multi-drug resistant pathogens are nowadays available. It is essential to improve our current knowledge about pharmacokinetic properties of traditional and new antimicrobials to maximize its effectiveness and to minimize toxicity. These issues are even more important in critically ill patients because inadequate empirical therapy is associated with therapeutic failure and a poor outcome. Experts representing two scientific societies (Grupo de estudio de Infecciones en el Paciente Crítico de la SEIMC and Grupo de trabajo de Enfermedades Infecciosas de la SEMICYUC) have elaborated a consensus document based on the current scientific evidence to summarize recommendations for the treatment of serious infections caused by gram-positive cocci in critically ill patients.

New antimicrobial agents as therapy for resistant gram-positive cocci

Vancomycin- and methicillin-resistant gram-positive cocci have emerged as an increasingly problematic cause of hospital-acquired infections. We conducted a literature review of newer antibiotics with activity against vancomycin-resistant and methicillin-resistant gram-positive cocci. Quinupristin/dalfopristin, linezolid, daptomycin, and tigecycline have in vitro activity for methicillin-resistant staphylococci and are superior to vancomycin for vancomycin-resistant isolates. Dalbavancin, telavancin, and oritavancin are new glycopeptides that have superior pharmacodynamic properties compared to vancomycin. We review the antibacterial spectrum, clinical indications and contraindications, pharmacologic properties, and adverse events associated with each of these agents. Daptomycin has rapid bactericidal activity for Staphylococcus aureus and is approved for use in bacteremia and right-sided endocarditis. Linezolid is comparable to vancomycin in patients with methicillin-resistant S. aureus (MRSA) pneumonia and has pharmacoeconomic advantages given its oral formulation. Quinupristin/dalfopristin is the drug of choice for vancomycin-resistant Enterococcus faecium infections but has no activity against Enterococcus faecalis. Tigecycline has activity against both enterococcus species and MRSA; it is also active against Enterobacteriaceae and anaerobes which allows for use in intra-abdominal and diabetic foot infections. A review of numerous in vitro and animal model studies shows that interaction between these newer agents and other antistaphylococcal agents for S. aureus are usually indifferent (additive).