The aetiology of severe community-acquired pneumonia and its impact on initial, empiric, antimicrobial chemotherapy

Treatment with andrographolide sulfonate provides additional benefits to imipenem in a mouse model of Klebsiella pneumoniae pneumonia

Klebsiella pneumoniae is a primary cause of community-acquired and nosocomial respiratory infections, and K. pneumoniae resistance to the current treatment approach with carbapenem is worsening. Andrographolide is a natural diterpenoid from Andrographis paniculata that was shown to exert anti-inflammatory activity. We herein show that pretreatment with a water-soluble andrographolide sulfonate significantly attenuate lung injury and infiltration of inflammatory cells. Interestingly, mice receiving combined treatment with andrographolide sulfonate displayed perfect survival rate than the mice treatment with imipenem alone, and monocyte chemotactic protein 5 (MCP-5) level was decreased further. These findings suggest that andrographolide sulfonate could as a potential synergist for antibiotic treatment of bacteria-induced inflammation.

Etiology and epidemiology of community-acquired pneumonia in adults requiring hospital admission: A prospective study in rural Central Philippines

BACKGROUND

Community-acquired pneumonia (CAP) is a common cause of morbidity and mortality among adults worldwide. However, the distribution of the etiology of CAP varies from one country to another, with limited data from rural areas.

METHODS

A prospective hospital-based study on adult CAP was conducted in Leyte, Central Philippines from May 2010 to May 2012. Blood, sputum, and nasopharyngeal samples obtained from patients were used to identify pathogens using standard microbiological culture methods and PCR.

RESULTS

Of the 535 patients enrolled, 38% were younger than 50 years old. More than half of the patients had an underlying disease, including pulmonary tuberculosis (22%). The detection rate was higher for bacteria (40%) than viruses (13%). Haemophilus influenzae (12%) was the most commonly detected bacterium and influenza virus (5%) was the most commonly detected virus. The proportion of CAP patients with Mycobacterium tuberculosis infection was higher in the younger age group than in the older age group. Among CAP patients, 14% died during hospitalization, and drowsiness on admission and SpO₂ <90% were independent risk factors for mortality.

CONCLUSIONS

Bacterial infections contribute substantially to the number of hospitalizations among CAP patients in rural Philippines. This study also highlights the importance of treatment of tuberculosis in reducing the burden of adult CAP in the country.

Klebsiella pneumoniae: Going on the Offense with a Strong Defense

Klebsiella pneumoniae causes a wide range of infections, including pneumonias, urinary tract infections, bacteremias, and liver abscesses. Historically, K. pneumoniae has caused serious infection primarily in immunocompromised individuals, but the recent emergence and spread of hypervirulent strains have broadened the number of people susceptible to infections to include those who are healthy and immunosufficient. Furthermore, K. pneumoniae strains have become increasingly resistant to antibiotics, rendering infection by these strains very challenging to treat. The emergence of hypervirulent and antibiotic-resistant strains has driven a number of recent studies. Work has described the worldwide spread of one drug-resistant strain and a host defense axis, interleukin-17 (IL-17), that is important for controlling infection. Four factors, capsule, lipopolysaccharide, fimbriae, and siderophores, have been well studied and are important for virulence in at least one infection model. Several other factors have been less well characterized but are also important in at least one infection model. However, there is a significant amount of heterogeneity in K. pneumoniae strains, and not every factor plays the same critical role in all virulent Klebsiella strains. Recent studies have identified additional K. pneumoniae virulence factors and led to more insights about factors important for the growth of this pathogen at a variety of tissue sites. Many of these genes encode proteins that function in metabolism and the regulation of transcription. However, much work is left to be done in characterizing these newly discovered factors, understanding how infections differ between healthy and immunocompromised patients, and identifying attractive bacterial or host targets for treating these infections.

Can we predict which patients with community-acquired pneumonia are likely to have positive blood cultures?

BACKGROUND

Blood cultures (BC) are commonly ordered during the initial assessment of patients with community-acquired pneumonia (CAP), yet their yield remains low. Selective use of BC would allow the opportunity to save healthcare resources and avoid patient discomfort. The study was to determine what demographic and clinical factors predict a greater likelihood of a positive blood culture result in patients diagnosed with CAP.

METHODS

A structured retrospective systematic chart audit was performed to compare relevant demographic and clinical details of patients admitted with CAP, in whom blood culture results were positive, with those of age, sex, and date-matched control patients in whom blood culture results were negative.

RESULTS

On univariate analysis, eight variables were associated with a positive BC result. After logistic regression analysis, however, the only variables statistically significantly associated with a positive BC were WBC less than 4.5 × 10(9)/L [likelihood ratio (LR): 7.75, 95% CI=2.89-30.39], creatinine >106 μmol/L (LR: 3.15, 95%CI=1.71-5.80), serum glucose<6.1 mmol/L (LR: 2.46, 95%CI=1.14-5.32), and temperature > 38 °C (LR: 2.25, 95% CI =1.21-4.20). A patient with all of these variables had a LR of having a positive BC of 135.53 (95% CI=25.28-726.8) compared to patients with none of these variables.

CONCLUSIONS

Certain clinical variables in patients with CAP admitted to hospitals do appear to be associated with a higher probability of a positive yield of BC, with combinations of these variables increasing this likelihood. We have identified a subgroup of CAP patients in whom blood cultures are more likely to be useful.

The Epidemiology of Alcohol Abuse and Pneumonia

The association between alcohol abuse and pneumonia has been recognized for more than two centuries and represents an enormous health burden worldwide. The first published notation of alcohol as a clinical risk factor for the development of pneumonia is now over 200 years old, and since then there have been over a 1,000 references in the medical literature confirming these observations. Even in this modern era of medicine pneumonia remains a common infection that afflicts over 450 million persons worldwide annually and causes 7 % of all deaths. When one considers that alcohol is the most commonly abused substance in the world, the enormous excessive burden that alcohol contributes to the morbidity and mortality of pneumonia represents a major public health consideration. In this chapter we review the foundational literature that has chronicled the evolution of our understanding of the association between pneumonia and alcohol abuse over the past century. In addition, we discuss some of the specific pathogens that are particularly associated with serious lung infections in individuals with alcohol use disorders. Finally, we consider some of the specific guidelines for the treatment and prevention of pneumonia in the setting of alcohol abuse.

Pneumonia in low and middle income countries: progress and challenges

Pneumonia remains the leading cause of childhood mortality and the most common reason for adult hospitalisation in low and middle income countries, despite advances in preventative and management strategies. In the last decade, pneumonia mortality in children has fallen to approximately 1.3 million cases in 2011, with most deaths occurring in low income countries. Important recent advances include more widespread implementation of protein-polysaccharide conjugate vaccines against Haemophilus influenzae type B and Streptococcus pneumoniae, implementation of case-management algorithms and better prevention and treatment of HIV. Determining the aetiology of pneumonia is challenging in the absence of reliable diagnostic tests. High uptake of new bacterial conjugate vaccines may impact on pneumonia burden, aetiology and empiric therapy but implementation in immunisation programmes in many low and middle income countries remains an obstacle. Widespread implementation of currently effective preventative and management strategies for pneumonia remains challenging in many low and middle income countries.

Mortality indicators in community-acquired pneumonia requiring intensive care in Turkey

BACKGROUND

Severe community-acquired pneumonia (SCAP) is a fatal disease. This study was conducted to describe an outcome analysis of the intensive care units (ICUs) of Turkey.

METHODS

This study evaluated SCAP cases hospitalized in the ICUs of 19 different hospitals between October 2008 and January 2011. The cases of 413 patients admitted to the ICUs were retrospectively analyzed.

RESULTS

Overall 413 patients were included in the study and 129 (31.2%) died. It was found that bilateral pulmonary involvement (odds ratio (OR) 2.5, 95% confidence interval (CI) 1.1-5.7) and CAP PIRO score (OR 2, 95% CI 1.3-2.9) were independent risk factors for a higher in-ICU mortality, while arterial hypertension (OR 0.3, 95% CI 0.1-0.9) and the application of non-invasive ventilation (OR 0.2, 95% CI 0.1-0.5) decreased mortality. No culture of any kind was obtained for 90 (22%) patients during the entire course of the hospitalization. Blood, bronchoalveolar lavage, and non-bronchoscopic lavage cultures yielded enteric Gram-negatives (n=12), followed by Staphylococcus aureus (n=10), pneumococci (n=6), and Pseudomonas aeruginosa (n=6). For 22% of the patients, none of the culture methods were applied.

CONCLUSIONS

SCAP requiring ICU admission is associated with considerable mortality for ICU patients. Increased awareness appears essential for the microbiological diagnosis of this disease.

SPLUNC1/BPIFA1 contributes to pulmonary host defense against Klebsiella pneumoniae respiratory infection

Epithelial host defense proteins comprise a critical component of the pulmonary innate immune response to infection. The short palate, lung, nasal epithelium clone (PLUNC) 1 (SPLUNC1) protein is a member of the bactericidal/permeability-increasing (BPI) fold-containing (BPIF) protein family, sharing structural similarities with BPI-like proteins. SPLUNC1 is a 25 kDa secretory protein that is expressed in nasal, oropharyngeal, and lung epithelia, and has been implicated in airway host defense against Pseudomonas aeruginosa and other organisms. SPLUNC1 is reported to have surfactant properties, which may contribute to anti-biofilm defenses. The objective of this study was to assess the importance of SPLUNC1 surfactant activity in airway epithelial secretions and to explore its biological relevance in the context of a bacterial infection model. Using cultured airway epithelia, we confirmed that SPLUNC1 is critically important for maintenance of low surface tension in airway fluids. Furthermore, we demonstrated that recombinant SPLUNC1 (rSPLUNC1) significantly inhibited Klebsiella pneumoniae biofilm formation on airway epithelia. We subsequently found that Splunc1(-/-) mice were significantly more susceptible to infection with K. pneumoniae, confirming the likely in vivo relevance of this anti-biofilm effect. Our data indicate that SPLUNC1 is a crucial component of mucosal innate immune defense against pulmonary infection by a relevant airway pathogen, and provide further support for the novel hypothesis that SPLUNC1 protein prevents bacterial biofilm formation through its ability to modulate surface tension of airway fluids.

Klebsiella pneumoniae and type 3 fimbriae: nosocomial infection, regulation and biofilm formation

The Gram-negative opportunistic pathogen Klebsiella pneumoniae is responsible for causing a spectrum of nosocomial and community-acquired infections. Globally, K. pneumoniae is a frequently encountered hospital-acquired opportunistic pathogen that typically infects patients with indwelling medical devices. Biofilm formation on these devices is important in the pathogenesis of these bacteria, and in K. pneumoniae, type 3 fimbriae have been identified as appendages mediating the formation of biofilms on biotic and abiotic surfaces. The factors influencing the regulation of type 3 fimbrial gene expression are largely unknown but recent investigations have indicated that gene expression is regulated, at least in part, by the intracellular levels of cyclic di-GMP. In this review, we have highlighted the recent studies that have worked to elucidate the mechanism by which type 3 fimbrial expression is controlled and the studies that have established the importance of type 3 fimbriae for biofilm formation and nosocomial infection by K. pneumoniae.

Bacteria-mediated acute lung inflammation

Mouse models of acute lung inflammation are critical for understanding the role of the innate immune response to pathogen associated molecular patterns, bacteria, and sepsis in humans. Bacterial infections in the lung elicit a range of immune reactions, depending on the pathogen, the level of exposure and the effectiveness of the host response. In general, mice have proven to be an acceptable surrogate model organism for studying specific aspects of human lung pathogenesis, including localized and systemic inflammation, necrotizing pneumonia, bacteriemia, and survival. Here, we describe a highly versatile model utilizing the gram-negative bacterium Klebsiella pneumoniae. Following a single challenge with this bacterium, mice develop a robust Th1 mediated immune response and clinically relevant disease progression. While these protocols have been optimized for K. pneumoniae, they can be applied to any gram-positive or gram-negative organism of interest.

Optimizing Treatment Outcomes in Severe Community-Acquired Pneumonia

Severe community-acquired pneumonia (CAP) is a life-threatening condition that requires intensive care unit (ICU) admission. Clinical presentation is characterized by the presence of respiratory failure, severe sepsis, or septic shock. Severe CAP accounts for approximately 5-35% of hospital-treated cases of pneumonia with the majority of patients having underlying comorbidities. The most common pathogens associated with this disease are Streptococcus pneumoniae, Legionella spp., Haemophilus influenzae, and Gram-negative enteric rods. Microbial investigation is probably helpful in the individual case but is likely to be more useful for defining local antimicrobial policies. The early and rapid initiation of empiric antimicrobial treatment is critical for a favorable outcome. It should include intravenous beta-lactam along with either a macrolide or a fluoroquinolone. Modifications of this basic regimen should be considered in the presence of distinct comorbid conditions and risk factors for specific pathogens. Other promising nonantimicrobial new therapies are currently being investigated. The assessment of severity of CAP helps physicians to identify patients who could be managed safely in an ambulatory setting. It may also play a crucial role in decisions about length of hospital stay and time of switching to oral antimicrobial therapy in different groups at risk. The most important adverse prognostic factors include advancing age, male sex, poor health of patient, acute respiratory failure, severe sepsis, septic shock, progressive radiographic course, bacteremia, signs of disease progression within the first 48-72 hours, and the presence of several different pathogens such as S. pneumoniae, Staphylococcus aureus, Gram-negative enteric bacilli, or Pseudomonas aeruginosa. However, some important topics of severity assessment remain controversial, including the definition of severe CAP. Prediction rules for complications or death from CAP, although far from perfect, should identify the majority of patients with severe CAP and be used to support decision-making by the physician. They may also contribute to the evaluation of processes and outcomes of care for patients with CAP.

Prevalence of plasmid mediated bla(TEM-1) and bla(CTX-M-15) type extended spectrum beta-lactamases in patients with sepsis

OBJECTIVE

To characterize the bacterial pathogens in patients having gram negative septicaemia. Further, to evaluate the antimicrobial resistance and underlying molecular mechanisms in these strains.

METHODS

A total number of 70 cases of gram negative sepsis were included in this prospective, open labeled, observational study. Standard methods for isolation and identification of bacteria were used. Antimicrobial susceptibility and ESBL testing was performed by the standard disc diffusion method. PCR amplification was performed to identify bla(CTX-M), bla(SHV) and bla(TEM) type ESBLs. Conjugation experiments were performed to show resistant marker transfer.

RESULTS

The most prevalent isolates Escherichia coli (E. coli) 58.6%, Klebsiella Spp. 32.9% and Pseudomonas 8.6%, were resistant to most of the antimicrobials including cefazolin, ceftriaxone, cefuroxime, ampicillin and co-trimoxazole but sensitive to imipenem and meropenem. ESBL and MBL production was seen 7.3% and 12.2% of E. coli isolates respectively. Three isoaltes were found to have bla(CTX-M-15) and two of them also showed bla(TEM-1) type enxyme. Whereas, none of them showed bla(SHV). Conjugation experiments using J-53 cells confirmed these resistant markers as plasmid mediated.

CONCLUSIONS

This work highlights the molecular epidemiology of escalating antimicrobial resistance and likely switch over of bla(CTX-M-15) type extended spectrum beta-lactamases by bla(TEM) type ESBLs in India. Further, the antimicrobial resistance by horizontal gene transfer was predominant among Enterobacteraceae in the community setting.

Antimicrobial susceptibility of gram-negative pathogens isolated from patients with complicated intra-abdominal infections in South African hospitals (SMART Study 2004-2009): impact of the new carbapenem breakpoints

BACKGROUND

The Study for Monitoring Antimicrobial Resistance Trends (SMART) follows trends in resistance among aerobic and facultative anaerobic gram-negative bacilli (GNB) isolated from complicated intra-abdominal infections (cIAIs) in patients around the world.

METHODS

During 2004-2009, three centralized clinical microbiology laboratories serving 59 private hospitals in three large South African cities collected 1,218 GNB from complicated intra-abdominal infections (cIAIs) and tested them for susceptibility to 12 antibiotics according to the 2011 Clinical Laboratory Standards Institute (CLSI) guidelines.

RESULTS

Enterobacteriaceae comprised 83.7% of the isolates. Escherichia coli was the species isolated most commonly (46.4%), and 7.6% of these were extended-spectrum β-lactamase (ESBL)-positive. The highest ESBL rate was documented for Klebsiella pneumoniae (41.2%). Overall, ertapenem was the antibiotic most active against susceptible species for which it has breakpoints (94.6%) followed by amikacin (91.9%), piperacillin-tazobactam (89.3%), and imipenem-cilastatin (87.1%), whereas rates of resistance to ceftriaxone, cefotaxime, ciprofloxacin, and levofloxacin were documented to be 29.7%, 28.7%, 22.5%, and 21.1%, respectively. Multi-drug resistance (MDR), defined as resistance to three or more antibiotic classes, was significantly more common in K. pneumoniae (27.9%) than in E. coli (4.9%; p<0.0001) or Proteus mirabilis (4.1%; p<0.05). Applying the new CLSI breakpoints for carbapenems, susceptibility to ertapenem was reduced significantly in ESBL-positive E. coli compared with ESBL-negative isolates (91% vs. 98%; p<0.05), but this did not apply to imipenem-cilastatin (95% vs. 99%; p=0.0928). A large disparity between imipenem-cilastatin and ertapenem susceptibility in P. mirabilis and Morganella morganii was documented (24% vs. 96% and 15% vs. 92%, respectively), as most isolates of these two species had imipenem-cilastatin minimum inhibitory concentrations in the 2-4 mcg/mL range, which is no longer regarded as susceptible.

CONCLUSIONS

This study documented substantial resistance to standard antimicrobial therapy among GNB commonly isolated from cIAIs in South Africa. With the application of the new CLSI carbapenem breakpoints, discrepancies were noted between ertapenem and imipenem-cilastatin with regard to the changes in their individual susceptibilities. Longitudinal surveillance of susceptibility patterns is useful to guide recommendations for empiric antibiotic use in cIAIs.

Defining severe pneumonia

Pneumonia is an important clinical and public health problem. Identification and prediction of severe pneumonia are significant concerns. Attempts to define severe pneumonia should recognize that different purposes are served by different definitions; no single definition meets all needs. At present, several prediction models have been proposed or validated. Biomarkers are not yet ready for routine use. The authors recommend careful consideration of the implications of any given definition of pneumonia severity. Outcome studies are needed to integrate human and health care system factors with the application of pneumonia severity definitions.

Assessment of hypermucoviscosity as a virulence factor for experimental Klebsiella pneumoniae infections: comparative virulence analysis with hypermucoviscosity-negative strain

Background

Klebsiella pneumoniae displaying the hypermucoviscosity (HV) phenotype are considered more virulent than HV-negative strains. Nevertheless, the emergence of tissue-abscesses-associated HV-negative isolates motivated us to re-evaluate the role of HV-phenotype.

Results

Instead of genetically manipulating the HV-phenotype of K. pneumoniae, we selected two clinically isolated K1 strains, 1112 (HV-positive) and 1084 (HV-negative), to avoid possible interference from defects in the capsule. These well-encapsulated strains with similar genetic backgrounds were used for comparative analysis of bacterial virulence in a pneumoniae or a liver abscess model generated in either naïve or diabetic mice. In the pneumonia model, the HV-positive strain 1112 proliferated to higher loads in the lungs and blood of naïve mice, but was less prone to disseminate into the blood of diabetic mice compared to the HV-negative strain 1084. In the liver abscess model, 1084 was as potent as 1112 in inducing liver abscesses in both the naïve and diabetic mice. The 1084-infected diabetic mice were more inclined to develop bacteremia and had a higher mortality rate than those infected by 1112. A mini-Tn5 mutant of 1112, isolated due to its loss of HV-phenotype, was avirulent to mice.

Conclusion

These results indicate that the HV-phenotype is required for the virulence of the clinically isolated HV-positive strain 1112. The superior ability of the HV-negative stain 1084 over 1112 to cause bacteremia in diabetic mice suggests that factors other than the HV phenotype were required for the systemic dissemination of K. pneumoniae in an immunocompromised setting.

Defining and predicting severe community-acquired pneumonia

PURPOSE OF REVIEW

Community-acquired pneumonia is a significant clinical and public health problem. Defining and predicting severe pneumonia is difficult but important.

RECENT FINDINGS

Several new predictive models and more sophisticated approaches to describing pneumonia severity have been recently proposed, with subsequent validation in varied patient populations. Early data suggest that biomarkers may be useful in the future.

SUMMARY

Definitions of pneumonia severity depend on the relevant clinical or public health question. A health services reference definition seems most useful in most settings. The Infectious Disease Society of America/American Thoracic Society 2007 guidelines and SMART-COP are two recent promising methods for predicting severe pneumonia at the time of presentation. The traditional pneumonia severity index and Confusion Uremia Respiratory rate Blood pressure (CURB)-65 models are less useful. Accurate assessment of severity has important implications for triage, outcome, and defining populations for research applications. Novel biomarkers, while somewhat promising, do not yet have a validated role in pneumonia severity assessment.

Endogenous Klebsiella endophthalmitis associated with Klebsiella pneumoniae pneumonia

PURPOSE

To investigate the management, bacterial strains, antibiotic sensitivities, and visual outcomes in patients with Klebsiella pneumoniae pneumonia and endogenous Klebsiella endophthalmitis.

METHODS

Data were collected for treatments, antibiotic sensitivity patterns, and final visual outcomes.

RESULTS

The study included 10 eyes of 9 patients with a median age of 42 years (range, 0-86 years). Diabetes mellitus was the most common comorbid risk factor (n = 5, 56%). Nine eyes (90%) were treated with intravitreal antibiotics, and one with pars plana vitrectomy and intravitreal antibiotics. One eye achieved a favorable visual acuity of 20/20; however, 6 eyes developed vision of no light perception, including 2 of evisceration. Two nosocomial K. pneumoniae isolates were extended-spectrum-beta-lactamase-producing strains, which demonstrated the resistance to amikacin and ceftazidime.

CONCLUSIONS

Ophthalmologists and physicians should be aware of Klebsiella pneumonia as a possible cause of endogenous endophthalmitis, and endogenous Klebsiella endophthalmitis usually causes poor visual outcomes.

NLRP3 (NALP3, Cryopyrin) facilitates in vivo caspase-1 activation, necrosis, and HMGB1 release via inflammasome-dependent and -independent pathways

Bacterial infection elicits a range of beneficial as well as detrimental host inflammatory responses. Key among these responses are macrophage/monocyte necrosis, release of the proinflammatory factor high-mobility group box 1 protein (HMGB1), and induction of the cytokine IL-1. Although the control of IL-1beta has been well studied, processes that control macrophage cell death and HMGB1 release in animals are poorly understood. This study uses Klebsiella pneumonia as a model organism because it elicits all three responses in vivo. The regulation of these responses is studied in the context of the inflammasome components NLRP3 and ASC, which are important for caspase-1 activation and IL-1beta release. Using a pulmonary infection model that reflects human infection, we show that K. pneumonia-induced mouse macrophage necrosis, HMGB1, and IL-1beta release are dependent on NLRP3 and ASC. K. pneumoniae infection of mice lacking Nlrp3 results in decreased lung inflammation and reduced survival relative to control, indicating the overall protective role of this gene. Macrophage/monocyte necrosis and HMGB1 release are controlled independently of caspase-1, suggesting that the former two responses are separable from inflammasome-associated functions. These results provide critical in vivo validation that the physiologic role of NLRP3 and ASC is not limited to inflammasome formation.

Virulence characteristics of Klebsiella and clinical manifestations of K. pneumoniae bloodstream infections

Differences in clinical manifestations are due to virulence factors expressed by the organism.

We studied 455 consecutive episodes of Klebsiella pneumoniae bacteremia occurring in 7 countries. Community-acquired pneumonia and an invasive syndrome of liver abscess, meningitis, or endophthalmitis occurred only in Taiwan and South Africa. Infections by K1 and K2 capsular serotype, the mucoid phenotype, and aerobactin production were important determinants of virulence. The mucoid phenotype was seen in 94% of isolates in patients with community-acquired pneumonia and in 100% of isolates that caused the invasive syndrome in Taiwan and South Africa, compared with only 2% of isolates elsewhere. Mortality of mice injected with mucoid strains (69%) was strikingly higher than that occurring in mice injected with nonmucoid strains (3%, p<0.001). Differences in clinical features of bacteremic infection with K. pneumoniae are due to the virulence factors expressed by the organism.

Severe community-acquired pneumonia: approach to therapy

Despite substantial progress in therapeutic options, severe community-acquired pneumonia (CAP) remains a significant cause of morbidity and mortality worldwide. Recognising the clinical importance of CAP over the past several years, different medical societies and health organisations in different countries have proposed specific guidelines for the management of CAP. Early and rapid initiation of antimicrobial therapy has been advocated for a favourable outcome. Treatment is empirical as the diagnostic yield for potential pathogens does not exceed 50%. Dual therapy is emerging as the preferred therapy for severe CAP. The regimen is based on an epidemiological approach with emphasis on covering both typical and atypical pathogens. Non-antimicrobial adjuvant therapies including non-invasive ventilation and immunomodulatory agents are emerging as promising area for future development.

100 years of respiratory medicine: pneumonia

In this review, we aim to lead the readers through the historical highlights of pathophysiological concepts and treatment of pneumonia. Understanding the aetiology, the risk factors and the pathophysiology influenced our management approaches to pneumonia. Pneumonia is still associated with significant morbidity and mortality, presents in a variety of healthcare settings and imposes a considerable cost to healthcare services. Guidelines have been issued by international and national scientific societies in order to spread the scientific knowledge on this important disease and to improve its management.

Severe community-acquired pneumonia: an Australian perspective

BACKGROUND

Severe community-acquired pneumonia (CAP) is a common disease with a relatively high mortality. The initial treatment is empirical, based on a broad range of potential pathogens. There are minimal published data describing microbiological causes of pneumonia in Australia.

AIMS

To describe the aetiology and characteristics of severe CAP in patients requiring intensive care unit (ICU) admission, to identify factors predicting mortality and to audit current practices of investigation and antibiotic management of these patients from an Australian perspective.

METHODS

A retrospective analysis of patient case notes was performed for 96 consecutive patients admitted to two ICU with severe CAP. Data recorded included patient demographics, comorbidities, antimicrobial treatment, investigations and outcome (mortality, length of stay).

RESULTS

Overall, mortality was 32%. A microbiological diagnosis was made in 46% of patients. The most frequent causative organisms were Streptococcus pneumoniae (13 cases), influenza A (9), Haemophilus influenzae (5) and Staphylococcus aureus (4); aerobic Gram-negative bacilli collectively accounted for five cases. Blood cultures were positive in 20% of patients. Seventy patients (73%) required mechanical ventilation and 61 patients (63%) required inotropic support. Laboratory abnormalities including acute renal failure, metabolic acidosis and coagulopathy were frequent. Factors associated with mortality on multivariate analysis were age, antibiotic administration prior to hospital presentation, delay in hospital antibiotic administration of more than 4 h, and presence of multilobar or bilateral consolidation on chest X-ray.

CONCLUSIONS

Severe CAP requiring ICU admission was associated with a mortality rate of 32%, despite appropriate antimicrobial therapy including a beta-lactam and a macrolide antibiotic in most cases. Causative organisms identified were similar to those found in previous studies. High rates of viral causes (28% of identified pathogens) were noted. Low rates of legionellosis and other atypical causes were found, most probably due to a lack of systematic testing for these agents.

The changing pathogens of complicated parapneumonic effusions or empyemas in a medical intensive care unit

OBJECTIVES

To assess the incidence, pathogens, and outcome of complicated parapneumonic effusions or empyemas in a medical intensive care unit (MICU) patients with pleural effusions.

DESIGN AND SETTING

Prospective study of febrile MICU patients with pleural effusion carried out in a tertiary care hospital between April 2001 and September 2003.

PATIENTS

The study included 175 patients with a temperature above 38 degrees for more than 8 h with evidence of pleural effusion confirmed by chest radiography and ultrasound.

INTERVENTION

Routine thoracentesis and effusion cultures.

RESULTS

The prevalence of complicated parapneumonic effusions or thoracic empyemas in febrile MICU patients with pleural effusions was 45% (78/175). A total of 78 micro-organisms were isolated from the pleural fluid of 58 patients (positive microbiological culture 74%) including aerobic Gram-negative (n=45), aerobic Gram-positive (n=23), anaerobic (n=5), Myobacterium tuberculosis (n=3), and Candida (n=2). The infection-related mortality rate of complicated parapneumonic effusions or empyemic patients in the MICU was 41% (32/78).

CONCLUSION

The development of complicated parapneumonic effusions or thoracic empyemas in MICU patients is a high-mortality disease. The increasing incidence of aerobic Gram-negative pathogens in empyema has become a more urgent problem.

[Clinical picture and prognostic factors for severe community-acquired pneumonia in adults admitted to the intensive care unit]

OBJECTIVE

In Chile very little information is available on severe community-acquired pneumonia treated in intensive care units. This study describes the clinical picture, prognostic factors, and treatment of adult patients admitted to the intensive care unit for severe community-acquired pneumonia.

PATIENTS AND METHODS

A total of 113 consecutive patients were included in this prospective, descriptive study.

RESULTS

The mean (SD) age of the 113 patients was 73 (15). Of these, 95% had associated comorbidity, and 81% were in the high-risk classes of the Pneumonia Severity Index. Etiology was identified in 31%, and the most common pathogens were Streptococcus pneumoniae (40%), gram negative bacilli (17%), and Mycoplasma pneumoniae (6%). The main complications were the need for mechanical ventilation (45%), septic shock (26%), heart failure (24%), and arrhythmias (15%). Mortality at 30 days was 16.8%, and multivariate analysis revealed the following factors to be associated with a greater risk of death: acute renal failure (odds ratio: 5.1), and glycemia above 300 mg/dL (odds ratio: 7.2).

CONCLUSIONS

The patients with severe pneumonia admitted to the intensive care unit are elderly, with a high level of comorbidity and complications, but most survive.

[A comparison of moxifloxacin and amoxicillin in the treatment of community-acquired pneumonia in Latin America: results of a multicenter clinical trial]

Since community-acquired pneumonia (CAP) is a common disease with a high morbidity rate, it is important to obtain information concerning its etiology and susceptibility to antibiotics across different geographic areas. This study presents data obtained in 5 Latin American counties in the course of an international clinical trial that evaluated the efficacy and safety of treatment with either moxifloxacin or amoxicillin administered for 10 days to patients suspected of having CAP caused by a pneumococcal infection. Details are given of the pathogens identified, the patterns of sensitivity to antibiotics observed, and the clinical and microbiological results obtained.A total of 84 patients were studied, of whom 70 (83.3%) were evaluated at the end of the trial to determine the efficacy and safety of the treatment received. Gram-positive bacteria were found in samples from 29 patients (80.5%). The pathogen was Streptococcus pneumoniae in 28 of those cases (77.7%). Gram-negative bacteria were found in 7 patients (19.4%), the most common being Haemophilus influenzae in 3 patients (8.3%). The presence of atypical microorganisms was detected in 18 of the 70 patients (25%), mainly Mycobacterium pneumoniae (n=11), and in 6 cases (8.5%) the infection was mixed. Ten strains of S. pneumoniae (35.7%) were shown to be susceptible to penicillin, 2 (7.1%) were highly resistant, and 16 (57.1%) showed moderate resistance. The clinical success rate at the final visit after treatment was 94.1% for moxifloxacin and 91.7% for amoxicillin. The results of this trial demonstrate a high prevalence of S. pneumoniae with reduced susceptibility to penicillin in patients with CAP in Latin America. It also revealed a high incidence of atypical pathogens and mixed infection in 8.6% of patients. This information should be taken into account when establishing protocols for empirical treatment of CAP in Latin America.

Community-acquired pneumonia in the emergency department: a practical approach to diagnosis and management

Pneumonia is one of the most common conditions for which patients seek emergency care. It is a challenging infection in that the spectrum of illness ranges from the nontoxic patient appropriate for outpatient antibiotics to the critically ill patient requiring intensive care hospitalization. Current data and diagnostic technology provide the emergency physician with the tools for an appropriately rapid evaluation and consideration of the differential diagnosis. Key critical thinking and application of published findings allow for intelligent empirical antibiotic treatment and risk stratification for the best disposition. Although antibiotic-resistant organisms increasingly are being identified, patients continue to benefit from early institution of standard ED treatment. Coverage for atypical organisms improves patient response and outcome. Finally, identification and treatment of the complications of pneumonia and accompanying sepsis must be considered by the ED physician when evaluating critically ill patients.

[Respiratory infections in adults hospitalized in internal medicine and pneumology departments. DIRA (Adult Respiratory Infection Day) study]

INTRODUCTION

Respiratory tract infections (RIs) are frequent processes that can require hospitalization or affect already hospitalized patients. The Foundation for the Study of Infection has promoted the DIRA (Adult Respiratory Infection Day) Project, with the aim of investigating and assessing the impact of this problem, particularly in Internal Medicine and Pneumology Departments.

METHODS

Prospective prevalence study involving 158 physicians in 100 Internal Medicine and Pneumology Departments. Data were collected on predetermined days, once every three months (total of four data sets) and included information on number of patients attended, number of patients with infection, and epidemiologic, clinical, microbiologic and treatment characteristics of patients with RI.

RESULTS

A total of 3,596 patients were hospitalized at the four time points. Among these, 39.1% presented clinical symptoms consistent with infection and 34.3% of these were RIs. The mean age of RI patients was 65.6 years, 68.8% were males, 84.1% had an underlying disease (most frequently chronic obstructive pulmonary disease) and 25.1% had one or more predisposing factors. Pneumonia was the most frequent diagnosis (41.3% of RIs). RI was documented microbiologically in 15.8% of cases. Antibiotic treatment was applied in 99.7% of patients with acute bronchitis and 81.8% of those with upper respiratory tract infection; penicillins were the most frequent treatment. Data are presented by diagnosis.

CONCLUSIONS

A substantial rate of respiratory infections was found in patients admitted to hospital Internal Medicine and Pneumology Departments, with pneumonia being the most frequent. There was a paucity of microbiologic documentation. It is likely that antibiotic treatment was not justified in the majority of patients with upper respiratory tract infections. A combination of two or more antimicrobial agents was used in about half of cases.

The contribution of blood cultures to the clinical management of adult patients admitted to the hospital with community-acquired pneumonia: a prospective observational study

STUDY OBJECTIVE

To assess the clinical usefulness of blood cultures (BCs) in the management of patients hospitalized with community-acquired pneumonia (CAP).

DESIGN

A prospective, observational study to investigate the contribution of BCs to the management and outcomes of adult patients presenting with CAP.

SETTING

Nineteen Canadian hospitals.

PATIENTS

Adults admitted to the hospital with CAP between January 1, 1998, and July 31, 1998.

INTERVENTIONS

The courses of therapy in patients for whom BC results yielded organisms considered to be clinically significant were analyzed to determine whether the BCs had contributed to management or outcome.

MEASUREMENTS AND RESULTS

Forty-three of 760 patients had significantly positive BC results. Patients with CAP who had BCs performed had a 1.97% chance (15 of 760 patients) of having a change of therapy directed by BC results. Patients in whom BCs yielded positive results had a 34.8% chance (15 of 43 patients) of having a change in therapy determined by BC results, and had a 58.1% chance (25 of 43 patients) of having a course of therapy contraindicated by BC results. Severity of illness, as measured by the pneumonia severity index, correlated poorly with the yield of BCs. BC results were positive in 8.0% of patients in risk classes I and II, 6.2% of patients in risk class III, 4.6% of patients in risk class IV, and 5.2% of patients in risk class V.

CONCLUSION

BCs have limited usefulness in the routine management of patients admitted to the hospital with uncomplicated CAP.

Community-acquired Klebsiella pneumoniae bacteremia: global differences in clinical patterns

We initiated a worldwide collaborative study, including 455 episodes of bacteremia, to elucidate the clinical patterns of Klebsiella pneumoniae. Historically, community-acquired pneumonia has been consistently associated with K. pneumoniae. Only four cases of community-acquired bacteremic K. pneumoniae pneumonia were seen in the 2-year study period in the United States, Argentina, Europe, or Australia; none were in alcoholics. In contrast, 53 cases of bacteremic K. pneumoniae pneumonia were observed in South Africa and Taiwan, where an association with alcoholism persisted (p=0.007). Twenty-five cases of a distinctive syndrome consisting of K. pneumoniae bacteremia in conjunction with community-acquired liver abscess, meningitis, or endophthalmitis were observed. A distinctive form of K. pneumoniae infection, often causing liver abscess, was identified, almost exclusively in Taiwan.

Carriage of gram-negative bacilli in young Brazilian children with community-acquired pneumonia

BACKGROUND

Gram-negative bacilli are not infrequently encountered as etiologic organisms of pneumonia in children in warm-climate countries.

OBJECTIVES

To investigate the nasopharyngeal carriage rate and antimicrobial susceptibility patterns of gram-negative bacilli colonizing children with community-acquired pneumonia in Fortaleza, Brazil.

METHODS

A single nasopharyngeal specimen was collected from children 2 months to 5 years of age presenting at one of the three children's hospitals in Fortaleza and fulfilling the World Health Organization criteria for pneumonia. Randomly recruited healthy children from public daycare centers and immunization clinics served as controls.

RESULTS

The study included 912 children, 482 (53%) with pneumonia and 430 (47%) controls. Aerobic gram-negative bacilli were seen in 79 (16%) of the 482 children with pneumonia and 51 (12%) of the 430 healthy controls. Nonfermentative gram-negative bacilli were seen in 85 (18%) of children with pneumonia and 54 (13%) of healthy controls. Neither gender, nutritional status, season, previous hospital admission nor antibiotic use was associated with carriage with gram-negative bacilli. However, pneumonia was associated with increased carriage, whereas concomitant colonization with Streptococcus pneumoniae or Haemophilus influenzae was associated with decreased carriage with gram-negative bacilli. Only 36% of all Escherichia species and 76% of all Klebsiella isolates were susceptible to cotrimoxazole; 90% of all Acinetobacter species were susceptible to gentamicin.

CONCLUSION

Nasopharyngeal carriage with gram-negative bacilli, in particular with Acinetobacter species, is common and associated with a clinical diagnosis of community-acquired pneumonia in children in Fortaleza, Brazil.

Prognostic factors in severe community-acquired pneumonia in patients without co-morbid illness

OBJECTIVES

We wished to determine the prognostic factors and the impact of initial empirical antibiotic therapy on the outcome of severe community-acquired pneumonia in patients without underlying co-morbid illness.

METHODOLOGY

This is a retrospective record review of consecutive patients with severe community-acquired pneumonia who were divided into those with and without underlying co-morbid illness.

RESULTS

There were 182 patients including 112 primary (no co-morbid illness) and 70 secondary (underlying co-morbid illness) pneumonias. The overall mortality was 41.8% and there were no differences in APACHE II score or mortality when comparing cases with primary (37.5%) and secondary infections (48.6%). The mortality was significantly higher in patients with negative microbiology. Univariate analysis identified a number of parameters and various antibiotic regimens, which appeared to be associated with a significantly poorer outcome. On multivariate analysis multilobar pulmonary consolidation, need for mechanical ventilation, inotropes and dialysis were documented to be independent predictors of mortality. Only in their absence could different antibiotic regimens be shown to have an apparent impact on outcome and further analysis suggested that the reason for these differences related predominantly to differences in the severity of the infection.

CONCLUSIONS

Markers of disease severity appear to be the most important predictors of outcome in patients with severe community-acquired pneumonia.

The role of atypical pathogens in community-acquired pneumonia

The atypical pathogens in community-acquired pneumonia traditionally have included Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella spp. Recent studies documenting their epidemiology and clinical characteristics have shown that these organisms are indistinguishable from the pneumococcus. Furthermore, therapy no longer depends on the specific bacterial cause of community-acquired pneumonia. Etiologic diagnosis is still difficult, although new methods are becoming available. This article focuses on these issues and on why the term atypical is no longer meaningful.

Community-acquired pneumonia: etiology, epidemiology, and outcome at a teaching hospital in Argentina

OBJECTIVE

To survey the etiology and epidemiology of community-acquired pneumonia (CAP) in relation to age, comorbidity, and severity and to investigate prognostic factors.

DESIGN

Prospective epidemiologic study, single center.

SETTING

University hospital at Buenos Aires, Argentina.

PATIENTS

Outpatients and inpatients fulfilling clinical criteria of CAP.

INTERVENTIONS

Systematic laboratory evaluation for determining the etiology, and clinical evaluation stratifying patients into mild, moderate, and severe CAP (groups 1 to 3), a clinical rule used for hospitalization.

RESULTS

During a 12-month period, 343 patients (mean age, 64.4 years; range, 18 to 102 years) were evaluated. We found 167 microorganisms in 144 cases (yield, 42%). Streptococcus pneumoniae, the most common pathogen, was isolated in 35 cases (24%). Mycoplasma pneumoniae, present in 19 (13%), was second in frequency in group 1; Haemophilus influenzae, present in 17 cases (12%), was second in group 2; and Chlamydia pneumoniae, present in 12 cases (8%), was second in group 3. Etiology could not be determined on the basis of clinical presentation; identifying the etiology had no impact on mortality. Some findings were associated with specific causative organisms and outcome. A significantly lower number of nonsurvivors received adequate therapy (50% vs 77%).

CONCLUSIONS

Age, comorbidities, alcohol abuse, and smoking were related with distinct etiologies. PaO(2) to fraction of inspired oxygen ratio < 250, aerobic Gram-negative pathogen, chronic renal failure, Glasgow score < 15, malignant neoplasm, and aspirative pneumonia were associated with mortality by multivariate analysis. Local microbiologic data could be of help in tailoring therapeutic guidelines to the microbiologic reality at different settings. The stratification schema and the clinical rule used for hospitalization were useful.

Severe community-acquired pneumonia. Risk factors and follow-up epidemiology

The aim of the study was to determine risk factors for severe community-acquired pneumonia (CAP) as well as to compare microbial patterns of severe CAP to a previous study from our respiratory intensive care unit (ICU) originating from 1984 to 1987. Patients admitted to the ICU according to clinical judgment were defined as having severe CAP. For the study of risk factors, a hospital-based case-control design was used, matching each patient with severe CAP to a patient hospitalized with CAP but not requiring ICU admission. Microbial investigation included noninvasive and invasive techniques. Overall, 89 patients with severe CAP were successfully matched to a control patient. The presence of an alcohol ingestion of >/= 80 g/d (odds ratio [OR] 3.9, 95% confidence interval [CI] 1.4 to 10.6, p = 0.008) was found to be an independent risk factor for severe CAP and prior ambulatory antimicrobial treatment (OR 0.37, 95% CI 0.17 to 0.79, p = 0.009) to be protective. Streptococcus pneumoniae (24%) continued to be the most frequent pathogen; however, 48% of strains were drug-resistant. "Atypical" bacterial pathogens were significantly more common (17% versus 6%, p = 0.006) and Legionella spp. less common (2% versus 14%, p = 0.004) than in our previous study, whereas gram-negative enteric bacilli (GNEB) and Pseudomonas aeruginosa continued to represent important pathogens (6% and 5%, respectively). Our findings provide additional evidence for the importance of the initiation of early empiric antimicrobial treatment for a favorable outcome of CAP. Variations of microbial patterns are only in part due to different epidemiological settings. Therefore, initial empiric antimicrobial treatment will also have to take into account local trends of changing microbial patterns.

Severe community-acquired pneumonia

Severe CAP is a life-threatening condition defined by the presence of respiratory failure or symptoms of severe sepsis or septic shock. It accounts for approximately 10% of hospitalized patients with CAP. The majority of patients with severe pneumonia have underlying comorbid illnesses, with COPD, alcoholism, chronic heart disease, and diabetes mellitus being the most frequent. S. pneumoniae, Legionella spp, GNEB (especially K. pneumoniae), H. influenzae, S. aureus/spp, Mycoplasma pneumoniae, respiratory viruses (especially influenza viruses), and P. aeruginosa represent the most important causative organisms of severe CAP. Rapid initiation of appropriate antimicrobial treatment is crucial for a favorable outcome. Initial antimicrobial treatment should be based on an epidemiological (empiric) approach. Microbial investigation may be helpful in the individual case but is probably more useful to define local antimicrobial policies based on local epidemiologic and susceptibility patterns. Mortality rates range from 21% to 54%. The most important prognostic factors include general health state of the patient, appropriateness of initial antimicrobial treatment, and the existence of bacteremia, as well as factors reflecting severe respiratory failure, severe sepsis, septic hypotension or shock, and the extent of infiltrates in chest radiograph. Initial antimicrobial treatment should consist of a second (or third) generation cephalosporin and erythromycin. Modifications of this basic regimen should be considered in the presence of distinct comorbid conditions and risk factors for distinct pathogens. Promising new approaches of nonantimicrobial treatment, including noninvasive ventilation, treatment of hypoxemia, and immunomodulation, are under investigation.