Importance of atypical pathogens of community-acquired pneumonia

Genotypic diversity, virulence, and molecular genetic tools in Histoplasma

SUMMARYHistoplasmosis is arguably the most common fungal respiratory infection worldwide, with hundreds of thousands of new infections occurring annually in the United States alone. The infection can progress in the lung or disseminate to visceral organs and can be difficult to treat with antifungal drugs. Histoplasma, the causative agent of the disease, is a pathogenic fungus that causes life-threatening lung infections and is globally distributed. The fungus has the ability to germinate from conidia into either hyphal (mold) or yeast form, depending on the environmental temperature. This transition also regulates virulence. Histoplasma and histoplasmosis have been classified as being of emergent importance, and in 2022, the World Health Organization included Histoplasma as 1 of the 19 most concerning human fungal pathogens. In this review, we synthesize the current understanding of the ecological niche, evolutionary history, and virulence strategies of Histoplasma. We also describe general patterns of the symptomatology and epidemiology of histoplasmosis. We underscore areas where research is sorely needed and highlight research avenues that have been productive.

In Silico molecular docking and dynamic analysis of natural compounds against major non-structural proteins of SARS-COV-2

COVID-19 has infected millions and significantly affected the global economy and healthcare systems. Despite continuous lockdowns, symptomatic management with currently available medications, and numerous vaccination drives, it is still far more difficult to control. Against COVID-19 infection, the pressure to develop vaccines and drugs has led to using some currently available medications like remdesivir, azithromycin, hydroxychloroquine and ritonavir. Understanding the importance and potential of harmless molecules to tackle SARS-COV-2, we designed the present study to identify potential natural phytocompounds. In the present study, we docked natural compounds and standard drugs against SARS-COV-2 proteins: papain-like protease, main protease and helicase. ADME/T and ProTox-II analyses were used to determine the toxicity of phytocompounds and drugs. The docking analysis revealed that podophyllotoxin gave the highest binding affinity scores of -8.1, -7.1 and -7.4 kcal/mol against PLpro, Mpro and helicase, respectively. Among the control drugs, doxycycline hydrochloride showed the highest binding affinity of -10.5, -8.4 and -8.8 kcal/mol against PLpro, Mpro and helicase. The results of this study revealed that podophyllotoxin and doxycycline hydrochloride could be promising inhibitors against SARS-Cov-2. Molecular dynamic simulations were executed for the best docked (PLpro-podophyllotoxin) complex, and the results displayed stable conformation and convergence. Energy plot results predicted a global minima average energy of -95 kcal/mol and indicated podophyllotoxin's role in stabilizing protein and making it compact and complex. FarPPI server used MM/GBSA approach to determine free binding affinity, and helicase-gallic acid complex showed the highest affinity, respectively. Therefore, it can be concluded that there is still a need for in vitro and in vivo studies to support further and validate these findings and validate these findings.Communicated by Ramaswamy H. Sarma.

Role of Intracellular Pulmonary Pathogens during SARS-CoV-2 Infection in the First Pandemic Wave of COVID-19: Clinical and Prognostic Significance in a Case Series of 1200 Patients

Background: Since 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic (COVID-19) has caused millions of deaths worldwide and is the second most serious pandemic after the Spanish flu. Despite SARS-CoV-2 infection having a dominant effect on morbidity and life-threatening outcomes, the role of bacterial co-infection in patients with COVID-19 is poorly understood. The present study aimed to verify the existence of bacterial co-infections and their possible role as cofactors worsening COVID-19-related clinical manifestations. Methods: All patients with suspected SARS-CoV-infection, hospitalised in COVID-19 wards at the Sant'Anna University Hospital of Ferrara, were retrospectively included in this single-centre study and their specific bacterial serologies were assessed. Univariate and logistic regression analyses were performed. Results: A total of 1204 individual records were retrieved. Among them, 959 were excluded because of a negative nasopharyngeal swab or missing data; of the eligible 245 patients, 51 were co-infected. Compared to patients with SARS-CoV-2 infection alone, those with Chlamydia pneumoniae or Mycoplasma pneumoniae co-infections had worse respiratory/radiological features and more intensive care unit admissions. However, the co-infection did not result in a higher mortality rate. Conclusions: The present study, comparing clinical, laboratory and radiological findings between patients with COVID-19 vs. those with co-infections (C. pneumoniae or M. pneumoniae) showed that, on admission, these features were worse in co-infected patients, although the mortality rate did not differ between the two groups.

Accuracy of a score predicting the presence of an atypical pathogen in hospitalized patients with moderately severe community-acquired pneumonia

BACKGROUND

Atypical pathogens (AP), present in some patients with community-acquired pneumonia (CAP), are intrinsically resistant to betalactam drugs, the mainstay of empirical antibiotic treatment. Adding antibiotic coverage for AP increases the risk of adverse effects and antimicrobial selection pressure, while withholding such coverage may worsen the prognosis if an AP is causative. A clinical model predicting the presence of AP would allow targeting atypical coverage for patients most likely to benefit.

METHODS

This is a secondary analysis of a multicentric randomized controlled trial that included 580 adults patients hospitalized for CAP. A predictive score was built using independent predictive factors for AP identified through multivariate analysis. Accuracy of the score was assessed using area under the receiver operating curve (AUROC), sensitivity, and specificity.

RESULTS

Prevalence of AP was 5.3%. Age < 75 years (OR 2.7, 95% CI 1.2-6.2), heart failure (OR 2.6, 95% CI 1.1-6.1), absence of chest pain (OR 3.0, 95% CI 1.1-8.2), natremia < 135 mmol/L (OR 3.0, 95% CI 1.4-6.6) and contracting the disease in autumn (OR 2.7, 95% CI 1.3-5.9) were independently associated with AP. A predictive score using these factors had an AUROC of 0.78 (95% CI 0.71-0.85). A score of 0 or 1 (present in 33% of patients) had 100% sensitivity and 35% specificity.

CONCLUSION

Use of a score built on easily obtained clinical and laboratory data would allow safe withholding of atypical antibiotic coverage in a significant number of patients, with an expected positive impact on bacterial resistance and drug adverse effects.

TRIAL REGISTRATION

NCT00818610.

Clinical and computed tomographic features of Legionella pneumonia with negative urine antigen test results

BACKGROUND

Legionella spp. can cause severe pneumonia and most Legionella pneumonia (LP) cases are diagnosed using the urine antigen test (UAT). However, diagnosis of LP with negative UAT results (LPNUAT) is challenging. We investigated the clinical and radiological features of LPNUAT.

METHODS

We retrospectively collected LP cases with positive UAT (LPPUAT) and cases of suspected LP with negative UAT that were examined by Legionella culture between July 2014 and March 2020. We investigated the clinical and CT findings for LP that showed negative UAT results and was diagnosed by culture and compared these findings with those for other pneumonias suspicious for LP with negative results in UAT and Legionella culture (OPSLP).

RESULTS

Eight LPNUAT, 20 LPPUAT, and 19 OPSLP cases were included in this study. There were no significant differences in the clinical and CT findings between LPPUAT and LPNUAT when examined by UAT. In LPNUAT, dyspnea, renal dysfunction, liver dysfunction, and bilateral lesions were more commonly observed and inflammatory changes and the number of affected lobes were significantly higher when examined by culture than when examined by UAT. Comparison to OPSLP, LPNUAT did not show such differences, but rather showed disturbances in consciousness, hyponatremia and rhabdomyolysis. Furthermore, lobar consolidation was observed more frequently and bronchial wall thickening and centrilobular nodules were observed less frequently in LPNUAT.

CONCLUSIONS

LP characteristics such as disturbance of consciousness, hyponatremia, rhabdomyolysis, lobar consolidation, and less bronchial wall thickening and centrilobular nodule contribute to the diagnosis of LP in patients with negative UAT results.

In Vitro Antiviral Activity of Doxycycline against SARS-CoV-2

In December 2019, a new severe acute respiratory syndrome coronavirus (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19), emerged in Wuhan, China. Despite containment measures, SARS-CoV-2 spread in Asia, Southern Europe, then in America and currently in Africa. Identifying effective antiviral drugs is urgently needed. An efficient approach to drug discovery is to evaluate whether existing approved drugs can be efficient against SARS-CoV-2. Doxycycline, which is a second-generation tetracycline with broad-spectrum antimicrobial, antimalarial and anti-inflammatory activities, showed in vitro activity on Vero E6 cells infected with a clinically isolated SARS-CoV-2 strain (IHUMI-3) with median effective concentration (EC₅₀) of 4.5 ± 2.9 µM, compatible with oral uptake and intravenous administrations. Doxycycline interacted both on SARS-CoV-2 entry and in replication after virus entry. Besides its in vitro antiviral activity against SARS-CoV-2, doxycycline has anti-inflammatory effects by decreasing the expression of various pro-inflammatory cytokines and could prevent co-infections and superinfections due to broad-spectrum antimicrobial activity. Therefore, doxycycline could be a potential partner of COVID-19 therapies. However, these results must be taken with caution regarding the potential use in SARS-CoV-2-infected patients: it is difficult to translate in vitro study results to actual clinical treatment in patients. In vivo evaluation in animal experimental models is required to confirm the antiviral effects of doxycycline on SARS-CoV-2 and more trials of high-risk patients with moderate to severe COVID-19 infections must be initiated.

Comparison of serological methods with PCR-based methods for the diagnosis of community-acquired pneumonia caused by atypical bacteria

Background

The diagnosis of community-acquired pneumonia (CAP) caused by Legionella pneumophila, Mycoplasma pneumoniae, and Chlamydophila pneumoniae is traditionally based on cultures and serology, which have special requirements, are time-consuming, and offer delayed results that limit their clinical usefulness of these techniques. We sought to develop a multiplex PCR (mPCR) method to diagnosis these bacterial infections in CAP patients and to compare the diagnostic yields obtained from mPCR of nasopharyngeal aspirates (NPAs), nasopharyngeal swabs (NPSs), and induced sputum (IS) with those obtained with specifc PCR commercial kits, paired serology, and urinary antigen.

Results

A total of 225 persons were included. Of these, 10 patients showed serological evidence of L. pneumophila infection, 30 of M. pneumoniae, and 18 of C. pneumoniae; 20 individuals showed no CAP. The sensitivities were mPCR-NPS = 23.1 %, mPCR-IS = 57.1 %, Seeplex®-IS = 52.4 %, and Speed-oligo®-NPA/NPS = 11.1 %, and the specificities were mPCR-NPS = 97.1 %, mPCR-IS = 77.8 %, Seeplex®-IS = 92.6 %, and Speed-oligo®-NPA/NPS = 96.1 %. The concordance between tests was poor (kappa <0.4), except for the concordance between mPCR and the commercial kit in IS (0.67). In individuals with no evidence of CAP, positive reactions were observed in paired serology and in all PCRs.

Conclusions

All PCRs had good specificity but low sensitivity in nasopharyngeal samples. The sensitivity of mPCR and Seeplex® in IS was approximately 60 %; thus, better diagnostic techniques for these three bacteria are required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12952-016-0047-y) contains supplementary material, which is available to authorized users.

History of antibiotics: from fluoroquinolones to daptomycin (Part 2)

In the Modern Era, physicians attested to the reciprocal influence among a technologically advanced society, rapid scientific progresses in medicine, and the need for new antimicrobials. The results of these changes were not only seen in the prolongation of life expectancy but also by the emergence of new pathogens. We first observed the advent of Gram-negative bacteria as a major source of nosocomial infections. The treatment of these microorganisms was complicated by the appearance and spread of drug resistance. We first focused on the development of two major classes of antimicrobials still currently used for the treatment of Gram-negative bacteria, such as fluoroquinolones and carbapenemes. Subsequently, we directed our attention to the growth of the incidence of infections due to Methicillin-Resistant Staphylococcus aureus (MRSA). Although the first MRSA was already isolated in 1961, the treatment of this new pathogen has been based on the efficacy of vancomycin for more than four decades. Only in the last 15 yr, we assisted in the development of new antimicrobial agents such as linezolid and daptomycin.

Clinical Characteristics and Response to Newer Quinolones inLegionellaPneumonia: A Report of 28 Cases

Twenty-eight (11.6%) out of 241 Spanish patients enrolled in an international phase III clinical trial of mild to moderate community-acquired pneumonia (CAP) comparing gemifloxacin vs. trovafloxacin were diagnosed of Legionnaires' disease. A definite diagnosis was established by seroconversion in 13 patients of whom only 2 had a positive Legionella urinary antigen. The remaining 15 patients were possible Legionella infections based on a single elevated IgG titer (> or = 1:512). All patients had a radiologically confirmed diagnosis of pneumonia, 5 (19%) patients were older than 65, comorbidity was present in 9 (33%), and 10 (36%) had to be hospitalized. Fifteen patients were treated with oral gemifloxacin (320 mg/day) and 13 with oral trovafloxacin (200 mg/day). Overall, clinical success occurred in 25 (89.3%) patients after 7 days of treatment and only 1 patient needed a 14-day treatment. There were only one adverse event withdrawal and one clinical failure, and no patients died. In light of the favorable clinical outcome, the use of newer fluoroquinolones seems adequate for the treatment of suspected or proven Legionella pneumonia.

Distinctive features between community-acquired pneumonia (CAP) due to Chlamydophila psittaci and CAP due to Legionella pneumophila admitted to the intensive care unit (ICU)

The spectrum of community-acquired pneumonia (CAP) due to Chlamydophila psittaci ranges from mild, self-limited CAP, to acute respiratory failure. We performed a retrospective study of 13 consecutive patients with CAP due to C. psittaci and 51 patients with legionellosis admitted in one intensive care unit (ICU) (1993-2011). As compared to patients with legionellosis, patients with psittacosis were younger (median age 48 [38-59] vs. 60 [50-71] years, p = 0.007), less frequently smokers (38 vs. 79 %, p < 0.001), with less chronic disease (15 vs. 57 %, p = 0.02), and longer duration of symptoms before admission (median 6 [5-13] vs. 5 [3-7] days, p = 0.038). They presented with lower Simplified Acute Physiology Score II (median 28 [19-38] vs. 39 [28-46], p = 0.04) and less extensive infiltrates on chest X-rays (median 2 [1-3] vs. 3 [3-4] lobes, p = 0.007). Bird exposure was mentioned in 100 % of psittacosis cases, as compared to 5.9 % of legionellosis cases (p < 0.0001). Extrapulmonary manifestations, biological features, and mortality (15.4 vs. 21.6 %, p = 0.62) were similar in both groups. In conclusion, severe psittacosis shares many features with severe legionellosis, including extrapulmonary manifestations, biological features, and outcome. Psittacosis is an important differential diagnosis for legionellosis, especially in cases of bird exposure, younger age, and more limited disease progression over the initial few days.

The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America

Evidenced-based guidelines for management of infants and children with community-acquired pneumonia (CAP) were prepared by an expert panel comprising clinicians and investigators representing community pediatrics, public health, and the pediatric specialties of critical care, emergency medicine, hospital medicine, infectious diseases, pulmonology, and surgery. These guidelines are intended for use by primary care and subspecialty providers responsible for the management of otherwise healthy infants and children with CAP in both outpatient and inpatient settings. Site-of-care management, diagnosis, antimicrobial and adjunctive surgical therapy, and prevention are discussed. Areas that warrant future investigations are also highlighted.

Microfluidic platform versus conventional real-time polymerase chain reaction for the detection of Mycoplasma pneumoniae in respiratory specimens

Rapid, accurate diagnosis of community-acquired pneumonia (CAP) due to Mycoplasma pneumoniae is compromised by low sensitivity of culture and serology. Polymerase chain reaction (PCR) has emerged as a sensitive method to detect M. pneumoniae DNA in clinical specimens. However, conventional real-time PCR is not cost-effective for routine or outpatient implementation. Here, we evaluate a novel microfluidic real-time PCR platform (Advanced Liquid Logic, Research Triangle Park, NC) that is rapid, portable, and fully automated. We enrolled patients with CAP and extracted DNA from nasopharyngeal wash (NPW) specimens using a biotinylated capture probe and streptavidin-coupled magnetic beads. Each extract was tested for M. pneumoniae-specific DNA by real-time PCR on both conventional and microfluidic platforms using Taqman probe and primers. Three of 59 (5.0%) NPWs were positive, and agreement between the methods was 98%. The microfluidic platform was equally sensitive but 3 times faster and offers an inexpensive and convenient diagnostic test for microbial DNA.

Acute Chlamydia pneumoniae infections in asthmatic and non-asthmatic military conscripts during a non-epidemic period

Chlamydia pneumoniae respiratory tract infections were studied in 512 male military conscripts (123 asthmatic and 389 non-asthmatic) taking part in 180-day service between July 2004 and July 2005 in Kajaani, Finland. Respiratory tract infections requiring a medical consultation were analysed prospectively. At baseline, at end of service, and during each episode of respiratory infection, blood samples were obtained for measurement of C. pneumoniae antibodies. Data concerning the clinical features of each infection episode were collected. Serological evidence of acute C. pneumoniae infection was found in 34 of the 512 conscripts with antibody data available, including 9.8% of the asthmatic subjects and 5.7% of the non-asthmatic subjects (p 0.111). A serological diagnosis could be made for 25 clinical episodes in 24 conscripts. The spectrum of respiratory tract infections included 13 episodes of mild upper respiratory tract infection and seven episodes of sinusitis, with five episodes involving asthma exacerbation. Two of three pneumonias were primary infections. Primary infections were diagnosed in five subjects, and re-infection/reactivation in 19 subjects, with the latter comprising 12 non-asthmatic subjects and seven asthmatic subjects (p 0.180). Prolonged infections were present in six asthmatic subjects and one non-asthmatic subject (p 0.001). A wide variety of respiratory tract infections, ranging from common cold to pneumonia, were associated with serologically confirmed C. pneumoniae infections. Infections were often mild, with common cold and sinusitis being the most common manifestations. Acute, rapidly resolved C. pneumoniae infections were equally common among asthmatic subjects and non-asthmatic subjects, whereas prolonged infections were more common among subjects with asthma.

Legionella pneumophilia serogroup 1 pneumonia recurrence postbone marrow transplantation

Recurrences of Legionnaires' disease have been reported uncommonly and rarely in immunocompromised children. We describe a 9-year-old girl with 2 episodes of culture proven infection with Legionella pneumophila. First episode occurred during induction chemotherapy for acute lymphoblastic leukemia and the second shortly after the bone marrow transplant.

Clinical and bacteriological outcomes in hospitalised patients with community-acquired pneumonia treated with azithromycin plus ceftriaxone, or ceftriaxone plus clarithromycin or erythromycin: a prospective, randomised, multicentre study

This study compared patients with moderate-to-severe community-acquired pneumonia (CAP) requiring hospitalisation, who received initial therapy with either intravenous ceftriaxone plus intravenous azithromycin, followed by step-down to oral azithromycin (n = 135), with patients who received intravenous ceftriaxone combined with either intravenous clarithromycin or erythromycin, followed by step-down to either oral clarithromycin or erythromycin (n = 143). Clinical and bacteriological outcomes were evaluated at the end of therapy (EOT; day 12-16) or at the end of study (EOS; day 28-35). At baseline, mean APACHE II scores were 13.3 and 12.6, respectively, with >50% of patients classified as Fine Pneumonia Severity Index (PSI) category IV or V. Clinical success rates (cure or improvement) in the modified intent-to-treat (MITT) population at EOT were 84.3% in the ceftriaxone/azithromycin group and 82.7% in the ceftriaxone/clarithromycin or erythromycin group. At EOS, MITT success rates (cure only) were 81.7% and 75.0%, respectively. Equivalent success rates in the clinically evaluable population were 83% and 87%, respectively, at EOT, and 79% and 78%, respectively, at EOS. MITT bacteriological eradication rates were 73.2% and 67.4%, respectively, at EOT, and 68.3% vs. 60.9%, respectively, at EOS. Mean length of hospital stay (LOS) was 10.7 and 12.6 days, and the mean duration of therapy was 9.5 and 10.5 days, respectively. The incidence of infusion-related adverse events was 16.3% and 25.2% (p 0.04), respectively. An intravenous-to-oral regimen of ceftriaxone/azithromycin was at least equivalent in efficacy and safety to the comparator regimen and appeared to be a suitable treatment option for hospitalised patients with CAP.

Mycoplasma pneumoniae: usual suspect and unsecured diagnosis in the acute setting

Mycoplasma pneumoniae is one of the most common known bacterial pathogens of the respiratory tract, especially in patients between 5 and 30 years of age. It may be encountered at a relatively high rate in the non-life-threatened fraction of Emergency Department (ED) patients presenting with upper respiratory symptoms or cough. Yet its hallmarks are very non-specific, including a great variety of presentations from mild pharyngitis to potentially life-threatening complications such as the Stevens-Johnson Syndrome. Here, we describe a typical case of pneumonia due to Mycoplasma pneumoniae in a young adult with mild pharyngitis as the leading symptom. Disease presentation, complications, diagnostic means, therapeutic options, and suspicious clinical settings are discussed to provide a review on the clinical aspects of the disease that are important in the ED setting.

Atypical pathogens as etiologic agents in hospitalized patients with community-acquired pneumonia in Korea: a prospective multi-center study

Local epidemiologic data on the etiologies of patients hospitalized with community-acquired pneumonia (CAP) is needed to develop guidelines for clinical practice. This study was conducted prospectively to determine the proportion of atypical bacterial pathogens in adults patients hospitalized with CAP in Korea between October 2001 and December 2002. Microbiological diagnosis was determined by serology for antibodies to Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila. Nucleic acid of M. pneumoniae and C. pneumoniae in respiratory samples and Legionella antigen in urine samples were detected. The study population consisted of 126 patients (71 males, 55 females), averaging 54.6 yr (SD+/-17.8), whose paired sera were available. An etiologic diagnosis for atypical pathogens was made in 18 patients (14.3%): C. pneumoniae 9 (7.1%), M. pneumoniae 8 (6.3%), and L. pneumophila 3 patients (2.4%). Streptococcus preumoniae and other typical pathogens were isolated from 36 patients (28.6%). Of 126 patients, 16 (12.7%) were admitted to intensive care unit and atypical pathogens were identified in 5 patients (31.3%). Initial clinical features of patients with pneumonia due to atypical, typical or undetermined pathogens were indistinguishable. We conclude that atypical pathogens should be seriously considered in hospitalized patients with CAP, when initiating empiric treatment in Korea.

The atypical pneumonias: clinical diagnosis and importance

The most common atypical pneumonias are caused by three zoonotic pathogens, Chlamydia psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever), and three nonzoonotic pathogens, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella. These atypical agents, unlike the typical pathogens, often cause extrapulmonary manifestations. Atypical CAPs are systemic infectious diseases with a pulmonary component and may be differentiated clinically from typical CAPs by the pattern of extrapulmonary organ involvement which is characteristic for each atypical CAP. Zoonotic pneumonias may be eliminated from diagnostic consideration with a negative contact history. The commonest clinical problem is to differentiate legionnaire's disease from typical CAP as well as from C. pneumoniae or M. pneumonia infection. Legionella is the most important atypical pathogen in terms of severity. It may be clinically differentiated from typical CAP and other atypical pathogens by the use of a weighted point system of syndromic diagnosis based on the characteristic pattern of extrapulmonary features. Because legionnaire's disease often presents as severe CAP, a presumptive diagnosis of Legionella should prompt specific testing and empirical anti-Legionella therapy such as the Winthrop-University Hospital Infectious Disease Division's weighted point score system. Most atypical pathogens are difficult or dangerous to isolate and a definitive laboratory diagnosis is usually based on indirect, i.e., direct flourescent antibody (DFA), indirect flourescent antibody (IFA). Atypical CAP is virtually always monomicrobial; increased IFA IgG tests indicate past exposure and not concurrent infection. Anti-Legionella antibiotics include macrolides, doxycycline, rifampin, quinolones, and telithromycin. The drugs with the highest level of anti-Legionella activity are quinolones and telithromycin. Therapy is usually continued for 2 weeks if potent anti-Legionella drugs are used. In adults, M. pneumoniae and C. pneumoniae may exacerbate or cause asthma. The importance of the atypical pneumonias is not related to their frequency (approximately 15% of CAPs), but to difficulties in their diagnosis, and their nonresponsiveness to beta-lactam therapy. Because of the potential role of C. pneumoniae in coronary artery disease and multiple sclerosis (MS), and the role of M. pneumoniae and C. pneumoniae in causing or exacerbating asthma, atypical CAPs also have public health importance.

Epidemiology of community-acquired pneumonia in adult patients at the dawn of the 21st century: a prospective study on the Mediterranean coast of Spain

This study presents data from a prospective study of adult patients with community-acquired pneumonia (CAP). Of 493 patients included in the study, 223 (45.2%) were aged > or = 65 years, and 265 (53.7%) had one or more underlying diseases, mostly chronic obstructive pulmonary disease, diabetes mellitus or dementia. In total, 281 microorganisms were identified in 250 (50.7%) patients, with two or more pathogens detected in 28 (5.7%) cases. Microbial diagnosis varied according to age, severity, co-morbidity and site-of-care, but there was much overlap among groups. Streptococcus pneumoniae was the single most prevalent organism in outpatients, patients admitted to hospital, and patients who died, either as a single pathogen or combined with another organism. Infections caused by 'atypical' pathogens were seen across all groups, including the elderly and patients with co-morbidities. Mortality varied according to the pneumonia severity index (PSI) of the pneumonia patient outcomes research team. Shock (OR 34.48), an age of > 65 years (OR 25) and altered mental status (OR 9.92) were factors associated independently with 30-day mortality. Key findings from this study were the advanced age of the population with CAP, and the high prevalence of dementia as an underlying disease. The study also revealed that microbiological diagnosis of CAP remains problematic. Although certain epidemiological features may help to predict the microbial aetiology, the overlap among groups reduces the usefulness of this information in guiding therapeutic decisions. Greater effort should be made to improve identification methods for microbial pathogens causing CAP.

Community-acquired pneumonia of mixed etiology: prevalence, clinical characteristics, and outcome

Community-acquired pneumonia (CAP) of mixed etiology has increasingly been appreciated in the literature, but its clinical significance remains unknown. The aim of this analysis was to describe the prevalence, clinical characteristics, and outcome of CAP of mixed etiology. Data were obtained from a 2-year prospective study of consecutive patients with CAP in whom an extensive microbiological workup was performed. Predefined strict criteria were used to establish the etiology. A total of 493 patients were included. A single pathogen was detected in 222 (45%) cases and two or more pathogens in 28 (5.7%) cases. Mixed infections were seen across all age groups and in patients treated both in hospital and as outpatients. The most frequent combinations of pathogens were those of a bacterium plus an "atypical" organism (28.6%) and of two bacterial organisms (28.6%). Compared with patients with monomicrobial pneumonia, patients with mixed pneumonia were more likely to have underlying conditions (64% vs. 45%, p=0.04) and dementia (25% vs. 10%, p=0.02). The incidence of a defined series of complications was higher in patients with mixed pneumonia (39.3% vs. 18.6%; OR=2.84; p=0.02). Community-acquired pneumonia of mixed etiology is uncommon. Patients with mixed pneumonia are more likely to have underlying medical conditions, and they may have a more severe course of disease.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

Empiric treatment of ambulatory community-acquired pneumonia: always include treatment for atypical agents

There are no data from proper studies to answer whether it is necessary to include antibiotics that are active against atypical pneumonia agents as part of the empiric therapy of CAP. Until such data are available, clinical judgment and severity of the pneumonic illness are the best guides to empiric antimicrobial therapy.

Re-evaluation of the therapy of severe pneumonia caused by Streptococcus pneumoniae

Pneumonia caused by Streptococcus pneumoniae is the most deadly form of community-acquired pneumonia. The death rate of bacteremic pneumococcal pneumonia has remained constant over the past 50 years. Several retrospective reviews of bacteremic pneumococcal pneumonia suggest that dual therapy with a beta-lactam and a macrolide antimicrobial agent is associated with a lower case fatality rate than therapy with a beta-lactam alone. These studies are reviewed, potential mechanisms are suggested, and future studies are discussed.

Efficacy and safety of sequential moxifloxacin for treatment of community-acquired pneumonia associated with atypical pathogens

In two prospective, randomized studies intravenous (IV)/oral (PO) moxifloxacin (400 mg q.i.d.) was compared to IV/PO antimicrobial comparator agents for the treatment of hospitalized patients with community-acquired pneumonia. Reported here are the pooled data for the sub-population with atypical pathogens. Of 101 intent-to-treat patients with atypical pathogens, a total of 39 moxifloxacin-treated and 47 comparator-treated subjects were microbiologically valid and included in the analysis. Clinical and bacteriological success rates were 95% for the moxifloxacin-treated and 94% for the comparator-treated subjects at the test-of-cure visit. The results indicate IV/PO moxifloxacin (400 mg q.i.d.) is an effective monotherapy for patients with CAP due to atypical pathogens.

Guidelines for Empiric Antimicrobial Prescribing in Community-Acquired Pneumonia

Empiric antimicrobial prescribing for community-acquired pneumonia remains a challenge, despite the availability of treatment guidelines. A number of key differences exist between North American and European guidelines, mainly in the outpatient setting. The North American approach is to use initial antimicrobial therapy, which provides coverage for Streptococcus pneumoniae plus atypical pathogens. Europeans tend to focus on providing pneumococcal coverage with less emphasis on covering for an atypical pathogen. Ambulatory patients without comorbidity are more likely to receive macrolide therapy in North America, whereas in Europe these patients would probably receive a beta-lactam agent. Major issues that are fundamental to this difference include the importance of providing therapy for atypical pathogens and the clinical significance of macrolide-resistant S pneumoniae. Prospective data are required to evaluate which of these two approaches offers clinical superiority.

Clinical diagnosis of Legionella pneumonia revisited: evaluation of the Community-Based Pneumonia Incidence Study Group scoring system

This prospective case-control study sought to identify differences in presentation between Legionella pneumonia (LP) diagnosed by urinary antigen and bacteremic pneumococcal pneumonia (PP), with the aim of assessing the ability of physicians to recognize such differences at admission and validating the Community-Based Pneumonia Incidence Study (CBPIS) Group scoring system for LP diagnosis. Significant differences in presentation were found: male sex, previous receipt of beta-lactam therapy, and temperature >39 degrees C were positively associated with LP; purulent sputum, pleuritic chest pain, and previous upper respiratory tract infection were negatively associated with LP. Physicians considered Legionella to be the most likely diagnosis in 52 (64%) of 81 LP cases and in 8 (6%) of 136 PP cases. Initial administration of a macrolide and rifampin and requests for urinary antigen testing for Legionella at admission were significantly more frequent among patients with LP. Overall, the CBPIS score did not differentiate reliably between LP and PP. Although certain presenting clinical features may allow recognition of LP, it is difficult to express them in a reliable scoring system.

Oral gatifloxacin in outpatient community-acquired pneumonia: results from TeqCES, a community-based, open-label, multicenter study

Gatifloxacin is an 8-methoxy fluoroquinolone with broad activity against respiratory tract pathogens, including those commonly associated with community-acquired pneumonia (CAP). To evaluate the efficacy and safety of oral gatifloxacin 400 mg once daily for seven to 14 days, community-based physicians enrolled adult outpatients with confirmed or suspected CAP in a prospective, single-arm, open-label, noncomparative study. Of 1488 clinically evaluable patients with radiographically confirmed or clinically suspected CAP, 1417 (95.2%) were cured. All strains of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, the most commonly isolated pathogens, were susceptible to gatifloxacin. Penicillin nonsusceptibility was seen in 32.6% of S. pneumoniae isolates, and beta-lactamase production was detected in H. influenzae (26.9%) and M. catarrhalis (88%) isolates. Clinical cure rates of 91%, 94%, and 92% were achieved in patients with S. pneumoniae, H. influenzae, and M. catarrhalis, respectively. All seven patients with fully penicillin-resistant S. pneumoniae (MIC > or =2 micro g/ml) were cured. Gatifloxacin was well tolerated, with the most common drug-related adverse events being nausea (2.8%) and diarrhea (1.7%). Gatifloxacin is effective and well tolerated as empiric therapy for CAP in the outpatient community setting.

Mycoplasma pneumoniae and Chlamydia pneumoniae cause lower respiratory tract disease in paediatric patients

New studies suggest that Mycoplasma pneumoniae and Chlamydia pneumoniae play a more significant role as causes of lower respiratory tract infections in childhood than was previously thought. In particular, the incidence of infections caused by these pathogens is high in children aged less than 5 years, the infections themselves seem to be a possible cause of wheezing, and may present a more complicated course when not treated with adequate antimicrobial agents. However, despite the increasing pathogenic significance of M. pneumoniae and C. pneumoniae, progress in fighting them is hampered by the lack of rapid and standardized diagnostic methods. This not only makes it practically impossible for practitioners to make a specific microbiological diagnosis, but has also had an adverse effect on treatment trials and has generated some questionable results. Carefully randomized and controlled trials are clearly needed to examine the effectiveness of different antibiotics against M. pneumoniae or C. pneumoniae and the optimal duration of therapy in various patient populations.

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.

In vitro activity of levofloxacin against contemporary clinical isolates of Legionella pneumophila, Mycoplasma pneumoniae and Chlamydia pneumoniae from North America and Europe

OBJECTIVE

To assess the activities of levofloxacin and the comparator agents erythromycin, clarithromycin, azithromycin and doxycycline against atypical respiratory pathogens.

METHODS

One hundred and forty-six Legionella pneumophila, 41 Mycoplasma pneumoniae and nine Chlamydia pneumoniae isolates were procured from various culture collections in North America and Europe and tested for susceptibility to the above agents by broth microdilution. The isolates came primarily from clinical sources and were collected from patients between 1995 and 1999.

RESULTS

Against L. pneumophila, levofloxacin was the most active agent, with an MIC(90) of 0.03 mg/L, twofold more active than clarithromycin (0.06 mg/L), 16-fold more active than erythromycin and azithromycin (0.5 mg/L) and 64-fold more active than doxycycline. Against M. pneumoniae, azithromycin (MIC(90) < or = 0.0005 mg/L) was the most active agent. However, two isolates of M. pneumoniae, one from the USA and one from Finland, were macrolide resistant (MIC > or = 4 mg/L), but levofloxacin susceptible (MIC 0.25 mg/L). The geographic origin of L. pneumophila and M. pneumoniae did not affect the MIC range for any antimicrobial agent tested. Against C. pneumoniae, clarithromycin was the most active agent, with an MIC range of < or =0.008-0.03 mg/L.

CONCLUSIONS

Levofloxacin had comparable activity to the other agents tested against the atypical respiratory pathogens, confirming its potential as an alternative for empirical therapy of community-acquired pneumonia.

Induced expression of melittin, an antimicrobial peptide, inhibits infection by Chlamydia trachomatis and Mycoplasma hominis in a HeLa cell line

As the number of pathogenic microbial strains resistant to different antibiotics increases, amphipathic peptides with antimicrobial activity are promising agents for the therapy of infectious diseases. This work deals with the effect of an amphipathic antimicrobial peptide, melittin, expressed within recombinant plasmid vectors, on infection with urogenital pathogens Chlamydia trachomatis and Mycoplasma hominis in HeLa cell culture. Recombinant plasmid constructs with the melittin gene under the control of the tetracycline-responsive promoter of human cytomegalovirus were obtained. We showed inhibition of C. trachomatis and M. hominis infection after the introduction of recombinant plasmid vectors expressing the melittin gene into the infected cell culture.

Association between initial empirical therapy and decreased length of stay among veteran patients hospitalized with community acquired pneumonia

This investigation assessed the impact of initial empirical antimicrobial therapy on the outcome of therapy for community acquired pneumonia (CAP) patients and on patients' length of stay (LOS) in the hospital. Hospital records for 165 patients with pneumonia admitted to the Edward Hines, Jr. VA Hospital between 1 October 1997, and 31 March 2000, were reviewed. Criteria for CAP were met for 92 of 165 patients. Comparisons were made between patients treated with azithromycin and with other parenteral antibiotics (the reference group). No statistical differences were observed between the treatment groups for the risk factors. The azithromycin group patients were slightly older with a mean age of 69 years versus 66 years (P=0.23). Patients treated with parenteral azithromycin had on average, a shorter length of hospitalization namely 4.6 days compared with 9.7 days for patients treated with the other antibiotics (log-rank test, P=0.0001). In order to make the two groups of patients more alike we considered patients' data set without intensive care unit (ICU) admissions. The conclusion was the same namely azithromycin monotherapy was associated with a decreased duration of hospital stay.

Emerging role of Mycoplasma pneumoniae and Chlamydia pneumoniae in paediatric respiratory-tract infections

Increased use of specialised diagnostic techniques over the past 10 years has allowed considerable new information to be obtained concerning Mycoplasma pneumoniae and Chlamydia pneumoniae infections. In children, these pathogens seem to have a more important role in causing respiratory-tract infections than previously thought; they have been associated with wheezing, and they are also frequent in children aged under 5 years. Contrary to original belief, no clinical, laboratory, or radiological findings seem to be unique to M. pneumoniae or C. pneumoniae; furthermore, there is no rapid and cost-effective diagnostic test capable of identifying these pathogens. Appropriate antimicrobial treatment of the infections they cause is needed to reduce the recurrent episodes of wheezing and other respiratory symptoms, to decrease morbidity, and to avoid the spread of the pathogens. However, a number of therapeutic issues remain unsolved.