Pathogens In Community-acquired Pneumonia Research Articles

Antimicrobial drug-resistant microbes associated with hospitalized community-acquired and healthcare-associated pneumonia: A multi-center study in Taiwan

Community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP) may be caused by potential antimicrobial drug-resistant (PADR) microbes. The aims of this study were to evaluate the incidences and risk factors associated with PADR microbes observed in patients with pneumonia occurring outside the hospital setting in Taiwan. We conducted a retrospective study of patients with CAP or HCAP admitted to six medical centers in the northern, central, and southern regions of Taiwan in 2007. The pathogens were evaluated by microbiological specimens within 72 hours after admission. Thepatients' comorbidities, pathogens, and outcomes were evaluated. The risk factors of PADR microbes were identified by logistic regression analysis. The enrolled patients exhibited HCAP (n=713) and CAP (n=933). The pathogens associated with HCAP (n=383) and CAP (n=441) included Pseudomonas spp. (29%vs. 10%, p<0.001), Klebsiella spp. (24% vs. 25%, p=0.250), Escherichia coli (6% vs. 8%, p=0.369), Haemophilus influnezae (3% vs. 7%, p=0.041), Streptococcus pneumoniae (2% vs. 6%, p=0.003) and methicillin-resistant Staphylococcus aureus (MRSA) (8% vs. 4%, p=0.008). The core pathogens of CAP and HCAP differed among the three regions of Taiwan. PADR microbes, including Pseudomonas spp. (n=191), Acinetobacter spp. (n=41), MRSA (n=49) and cefotaxime- or ceftazidime-resistant Enterbacteriaceae (n=25), were isolated from 13% of patients with CAP and 23% of patients with HCAP. Previous hospitalization, and neoplastic and neurological diseases were significant risk factors for acquiring PADR microbes. PADR microbes were common in patients with HCAP and CAP in Taiwan. Broad-spectrum antibiotics targeting PADR microbes should be administered to patients who have undergone previous hospitalization and who exhibit neurological disorders and/or malignancies.

The Role of Atypical Pathogens in Community-Acquired Pneumonia

The term atypical pneumonia was first used in 1938, and by the 1970s it was widely used to refer to pneumonia due to Mycoplasma pneumoniae, Legionella pneumophila (or other Legionella species), and Chlamydophila pneumoniae. However, in the purest sense all pneumonias other than the classic bacterial pneumonias are atypical. Currently many favor abolition of the term atypical pneumonia.This review categorizes atypical pneumonia pathogens as conventional ones; viral agents and emerging atypical pneumonia pathogens. We emphasize viral pneumonia because with the increasing availability of multiplex polymerase chain reaction we can identify the agent(s) responsible for viral pneumonia. By using a sensitive assay for procalcitonin one can distinguish between viral and bacterial pneumonia. This allows pneumonia to be categorized as bacterial or viral at the time of admission to hospital or at discharge from the emergency department and soon thereafter further classified as to the etiology, which should be stated as definite or probable.

Concomitant Pulmonary Tuberculosis in Hospitalized Healthcare-Associated Pneumonia in a Tuberculosis Endemic Area: A Multi-center Retrospective Study

BackgroundIn tuberculosis (TB) endemic areas, Mycobacterium tuberculosis is an important but easily misdiagnosed pathogen in community-acquired pneumonia (CAP). However, the occurrence of concomitant pulmonary tuberculosis (PTB) in hospitalized healthcare-associated pneumonia (HCAP) has never been investigated.Methods and FindingsSeven hundred and one hospitalized HCAP and 934 hospitalized CAP patients from six medical centers in Taiwan were included in this nationwide retrospective study. Concomitant PTB was defined as active PTB diagnosed within 60 days of admission due to HCAP or CAP. The predictors for concomitant PTB and the impact of PTB on the outcomes of pneumonia were investigated. Among the enrolled subjects, 21/701 (3%) of the HCAP patients and 25/934 (2.7%) of the CAP patients were documented to have concomitant PTB. In multivariate analysis, a history of previous anti-TB treatment (OR = 5.84, 95% CI: 2.29–20.37 in HCAP; OR = 3.33, 95% CI: 1.09–10.22 in CAP) and escalated pneumonia severity index (PSI) scores (OR = 1.014, 95% CI: 1.002–1.026, in HCAP; OR = 1.013, 95% CI: 1.001–1.026, in CAP) were independent predictors for concomitant PTB in both CAP and HCAP patients. Regarding treatment outcomes, HCAP patients with concomitant PTB were associated with more acute respiratory failure within 48 hours of admission (47.6% vs. 22.6%, p = 0.008), higher intensive care unit admission rate (61.9% vs. 35.7%, p = 0.014), longer hospitalization (39.6±34.1 vs. 23.7±27 days, p = 0.009), and higher in-hospital mortality (47.6% vs. 26.3%, p = 0.03) than those without concomitant PTB. Exposure to certain groups of antibiotics for the treatment of pneumonia was not associated with the occurrence of concomitant PTB.ConclusionsIn HCAP patients, the occurrence of concomitant PTB is comparable with that in CAP patients and associated with higher PSI scores, more acute respiratory failure, and higher in-hospital mortality.

Methicillin-Resistant Staphylococcus aureus and Community-Acquired Pneumonia: An Evolving Relationship

Methicillin-Resistant Staphylococcus aureus and Community-Acquired Pneumonia: An Evolving Relationship

Evaluation of Ceftaroline Activity versus Ceftriaxone against Clinical Isolates of Streptococcus pneumoniae with Various Susceptibilities to Cephalosporins in an In Vitro Pharmacokinetic/Pharmacodynamic Model

Drug resistance in Streptococcus pneumoniae, a frequent pathogen in community-acquired pneumonia, is increasing. Ceftaroline (active metabolite of ceftaroline fosamil) is a broad-spectrum intravenous cephalosporin with activity in vitro against drug-resistant Gram-positive organisms. We investigated ceftaroline at 600 mg every 12 h (q12h) (maximum concentration of the free, unbound drug in serum [fC(max)] is 15.2 μg/ml, and half-life [T(1/2)] is 2.5 h) versus ceftriaxone at 1 g q24h (fC(max) = 23 μg/ml, T(1/2) = 8 h) against six clinical S. pneumoniae isolates in a one-compartment in vitro pharmacokinetic/pharmacodynamic 96-h model (starting inoculum of 10(7) CFU/ml). Differences in CFU/ml (at 24 to 96 h) were evaluated by analysis of variance with a Tukey's post hoc test. Bactericidal activity was defined as a ≥ 3 log(10) CFU/ml decrease from the initial inoculum. Ceftaroline MICs were 0.06, 0.015, ≤ 0.008, 0.25, 0.25, and 0.5 μg/ml, and ceftriaxone MICs were 0.5, 0.25, 0.25, 4, 4, and 8 μg/ml for SP 1477, SP 669, SP 132, SP 211, SP 90, and SP 1466, respectively. Against the ceftaroline- and ceftriaxone-susceptible strain SP 1477, ceftaroline displayed sustained bactericidal activity (3 to 96 h, -5.49 log(10) CFU/ml) and was significantly (P ≤ 0.012) better than ceftriaxone (72 to 96 h, -2.03 log(10) CFU/ml). Against the ceftriaxone-resistant strains, ceftaroline displayed sustained bactericidal activity at 96 h and was significantly better than ceftriaxone (SP211 [-5.91 log(10) CFU/ml, P ≤ 0.002], SP 90 [-5.26 log(10) CFU/ml, P ≤ 0.008], and SP1466 [-5.14 log(10) CFU/ml, P ≤ 0.042]). Ceftaroline was the more effective drug and displayed sustained bactericidal activity. Ceftaroline fosamil may provide a therapeutic option to treat ceftriaxone-resistant S. pneumoniae infections.

Protease-activated receptor-1 impairs host defense in murine pneumococcal pneumonia: a controlled laboratory study

IntroductionStreptococcus pneumoniae is the most common causative pathogen in community-acquired pneumonia. Protease-activated receptor-1 (PAR-1) is expressed by multiple cell types present in the lungs and can be activated by various proteases generated during acute inflammation. The cellular effect of PAR-1 activation partially depends on the specific protease involved. We here determined the role of PAR-1 in the host response during murine pneumococcal pneumonia.MethodsWild-type (WT) and PAR-1 knockout (KO) mice were infected intranasally with viable S. pneumoniae and observed in a survival study or euthanized at 6, 24 or 48 hours of infection.ResultsPAR-1 KO mice had a better survival early after infection compared to WT mice. Moreover, PAR-1 KO mice had lower bacterial loads in lungs and blood at 24 hours and in spleen and liver at 48 hours after infection. This favorable response was accompanied by lower lung histopathology scores and less neutrophil influx in PAR-1 KO mice.ConclusionPAR-1 impairs host defense during murine pneumococcal pneumonia.

Respiratory syncytial virus (RSV) community-acquired pneumonia (CAP) in a hospitalized adult with human immunodeficiency virus (HIV) mimicking influenza A and Pneumocystis ( carinii) jiroveci pneumonia (PCP)

Background Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in young children, the elderly, and immunocompromised hosts, but RSV is a rare cause of community-acquired pneumonia (CAP) in hospitalized adults with human immunodeficiency virus (HIV). In patients with HIV, CAP is most frequently attributable to the usual bacterial respiratory pathogens that cause CAP in immunocompetent hosts, eg, Streptococcus pneumoniae or Hemophilus influenzae. Adults with HIV are also predisposed to intracellular CAP pathogens, ie, Mycoplasma tuberculosis, Salmonella spp., Pneumocystis (carinii) jiroveci (PCP), cytomegalovirus, and Legionella spp. This year, co-circulating in the community during influenza season were strains of human seasonal influenza A (H3N2) and swine influenza A (H1N1). During the influenza season, in adults hospitalized with HIV, the diagnostic possibilities should include influenza-like illnesses, eg, human parainfluenza virus types 3 and 4, human metapneumovirus, and pertussis. Case Report We present an adult with HIV, hospitalized for an influenza-like illness during influenza season. The differential diagnosis of CAP in this patient included influenza A and PCP. Conclusion We report on an adult patient with HIV with CAP that mimicked influenza and PCP, and was attributable to RSV.

Renal transplant with bronchiolitis obliterans organizing pneumonia (BOOP) attributable to tacrolimus and herpes simplex virus (HSV) pneumonia

BackgroundSolid organ transplants (SOTs) may be complicated by a wide variety of infectious and noninfectious pulmonary disorders. Transplant patients receive immunosuppressive drugs to prevent rejection, but these drugs also predispose them to infection. Because immunosuppressive therapy impairs T-lymphocyte function, ie, cell-mediated immunity, such therapy, not surprisingly, predisposes patients to intracellular pulmonary pathogens. Community-acquired pneumonia (CAP) in patients with SOT usually involves one of the common typical or atypical bacterial CAP pathogens infecting immunocompetent hosts. The most frequent intracellular CAP pathogens in SOTs during immunosuppressive therapy are viral, eg, cytomegalovirus (CMV), respiratory syncytial virus (RSV), and herpes simplex virus (HSV). In addition, intracellular fungal pathogens are also common in patients with SOTs during immunosuppressive therapy, eg, Pneumocystis (carinii) jiroveci pneumonia (PCP). In addition, a variety of noninfectious disorders are not uncommon in patients with SOTs, including bronchiolitis obliterans organizing pneumonia (BOOP). Bronchiolitis obliterans organizing pneumonia may be associated with a variety of infectious agents, or may be attributable to drugs, including some immunosuppressive agents. MethodsThe clinical approach to CAP in patients with SOTs may be based on the appearance of the chest x-ray (CXR) or chest computed tomography scan, combined with the degree of hypoxemia (ie, the A-a gradient). Patients with SOTs and with a normal or nearly normal CXR and a high degree of hypoxemia (A-a gradient, >35) most often have an early viral pneumonia, eg, CMV or early PCP. If the CXR reveals bilateral patchy interstitial infiltrates and severe hypoxemia, the differential diagnosis is limited to moderate or severe viral pneumonia or PCP. Patients with SOTs and presenting with diffuse infiltrates and mild to moderate hypoxemia (A-a gradient, <35) are usually prone to noninfectious disorders, eg, congestive heart failure, pulmonary embolism, or drug-induced pneumonias. In patients with SOTs and CAP with focal or lobar infiltrates, the distribution of pathogens is the same as in immunocompetent hosts, ie, either a bacterial or atypical CAP pathogen. Case Report and ConclusionA renal transplant patient developed bilateral patchy interstitial infiltrates with severe hypoxemia during hospitalization. The most likely differential diagnostic possibilities included PCP and BOOP. Bronchoalveolar lavage was performed to rule out PCP, and indicated cytopathic effects diagnostic of HSV pneumonia. Lung biopsy pathology confirmed the diagnosis of BOOP. In reviewing the patient’s medications, we surmised that tacrolimus may have caused BOOP. The tacrolimus was discontinued, and the patient received acyclovir for HSV pneumonia.

Cumulative clinical experience from over a decade of use of levofloxacin in community-acquired pneumonia: critical appraisal and role in therapy

Levofloxacin is the synthetic L-isomer of the racemic fluoroquinolone, ofloxacin. It interferes with critical processes in the bacterial cell such as DNA replication, transcription, repair, and recombination by inhibiting bacterial topoisomerases. Levofloxacin has broad spectrum activity against several causative bacterial pathogens of community-acquired pneumonia (CAP). Oral levofloxacin is rapidly absorbed and is bioequivalent to the intravenous formulation such that patients can be conveniently transitioned between these formulations when moving from the inpatient to the outpatient setting. Furthermore, levofloxacin demonstrates excellent safety, and has good tissue penetration maintaining adequate concentrations at the site of infection. The efficacy and tolerability of levofloxacin 500 mg once daily for 10 days in patients with CAP are well established. Furthermore, a high-dose (750 mg) and short-course (5 days) of once-daily levofloxacin has been approved for use in the US in the treatment of CAP, acute bacterial sinusitis, acute pyelonephritis, and complicated urinary tract infections. The high-dose, short-course levofloxacin regimen maximizes its concentration-dependent antibacterial activity, decreases the potential for drug resistance, and has better patient compliance.

Progress on the treatment of mycoplasma pneumoniae pneumonia

Mycoplasma pneumoniae is the common pathogen of community-acquired pneumonia in children. In recent years,the incidence of mycoplasma pneumoniae pneumonia(MPP) has increased year by year. And it is found that case reports about intractable MPP at home and abroad have also significantly increased. The treatments of MPP become the focus in clinical physicians. This paper summarized about progress of MPP in antibiotic therapy,immune therapy and other ancillary treatment. Key words: Mycoplasma pneumoniae; Pneumonia; Antibiotic; Immune treatment

Elderly Patients with Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) is a common infectious disease that still causes substantial morbidity and mortality. Elderly people are frequently affected, and several issues related to care of this condition in the elderly have to be considered. This article reviews current recommendations of guidelines with a special focus on aspects of the care of elderly patients with CAP. The most common pathogen in CAP is still Streptococcus pneumoniae, followed by other pathogens such as Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella species. Antimicrobial resistance is an increasing problem, especially with regard to macrolide-resistant S. pneumoniae and fluoroquinolone-resistant strains. With regard to β-lactam antibacterials, resistance by H. influenzae and Moraxella catarrhalis is important, as is the emergence of multidrug-resistant Staphylococcus aureus. The main management decisions should be guided by the severity of disease, which can be assessed by validated clinical risk scores such as CURB-65, a tool for measuring the severity of pneumonia based on assessment of confusion, serum urea, respiratory rate and blood pressure in patients aged ≥65 years. For the treatment of low-risk pneumonia, an aminopenicillin such as amoxicillin with or without a β-lactamase inhibitor is frequently recommended. Monotherapy with macrolides is also possible, although macrolide resistance is of concern. When predisposing factors for special pathogens are present, a β-lactam antibacterial combined with a β-lactamase inhibitor, or the combination of a β-lactam antibacterial, a β-lactamase inhibitor and a macrolide, may be warranted. If possible, patients who have undergone previous antibacterial therapy should receive drug classes not previously used. For hospitalized patients with non-severe pneumonia, a common recommendation is empirical antibacterial therapy with an aminopenicillin in combination with a β-lactamase inhibitor, or with fluoroquinolone monotherapy. With proven Legionella pneumonia, a combination of β-lactams with a fluoroquinolone or a macrolide is beneficial. In severe pneumonia, ureidopenicillins with β-lactamase inhibitors, broad-spectrum cephalosporins, macrolides and fluoroquinolones are used. A combination of a broad-spectrum β-lactam antibacterial (e.g. cefotaxime or ceftriaxone), piperacillin/tazobactam and a macrolide is mostly recommended. In patients with a predisposition for Pseudomonas aeruginosa, a combination of piperacillin/tazobactam, cefepime, imipenem or meropenem and levofloxacin or ciprofloxacin is frequently used. Treatment duration of more than 7 days is not generally recommended, except for proven infections with P. aeruginosa, for which 15 days of treatment appears to be appropriate. Further care issues in all hospitalized patients are timely administration of antibacterials, oxygen supply in case of hypoxaemia, and fluid management and dose adjustments according to kidney function. The management of elderly patients with CAP is a challenge. Shifts in antimicrobial resistance and the availability of new antibacterials will change future clinical practice. Studies investigating new methods to detect pathogens, determine the optimal antimicrobial regimen and clarify the duration of treatment may assist in further optimizing the management of elderly patients with CAP.

Healthcare-associated pneumonia: the state of evidence to date

As evidence about the importance of correct choice of empiric therapy in the setting of pneumonia accumulates, balancing antibiotic spectrum against the risk of selecting for resistant organisms gains importance. Healthcare-associated pneumonia (HCAP) defines a set of risk factors to underscore the probability of a resistant etiologic pathogen, requiring broader spectrum treatment than is generally needed in community-acquired pneumonia (CAP). Controversies persist as to whether HCAP is a useful designation for diagnosis, treatment and outcome prediction. HCAP represents a discrete syndrome, where offending organisms and outcomes differ from those for CAP. However, HCAP designation is neither a sensitive nor a specific system to predict the presence of a resistant organism. Several other instruments have been developed that require prospective validation. Recent findings that CAP guideline-concordant antibiotic treatment among HCAP patients does not alter outcomes is confounded by the emerging understanding that culture-negative HCAP may be successfully treated with therapy targeted at CAP pathogens. Because HCAP is an important emerging syndrome, a systematic approach to its study is critical. As evidence in this area evolves, it remains important for investigators and clinicians to identify knowledge gaps and to set the research agenda to resolve multiple unanswered questions.

A SPECTRUM OF CAUSATIVE BACTERIAL PATHOGENS IN COMMUNITY-ACQUIRED PNEUMONIA IN MULTIDISCIPLINARY HOSPITALS OF SMOLENSK

A spectrum of causative bacterial pathogens in community-acquired pneumonia in multidisciplinary hospitals of Smolensk

Recombinant human tissue factor pathway inhibitor exerts anticoagulant, anti‐inflammatory and antimicrobial effects in murine pneumococcal pneumonia

Streptococcus (S.) pneumoniae is the most common causative pathogen in community-acquired pneumonia and a major cause of sepsis. Recombinant human tissue factor pathway inhibitor (rh-TFPI) attenuates sepsis-induced coagulation and has been evaluated in clinical trials involving patients with sepsis and community-acquired pneumonia. To examine the effect of rh-TFPI on coagulation, inflammation and bacterial outgrowth in S. pneumoniae pneumonia in mice, with or without concurrent antibiotic treatment. Pneumonia was induced by intranasal inoculation with S. pneumoniae. Mice were treated with placebo, rh-TFPI, ceftriaxone or rh-TFPI combined with ceftriaxone. Early (8 h) and late (24 h) initiated treatments were evaluated. Samples were obtained 24 or 48 h after infection, for early and late initiated treatment, respectively. In vitro, placebo or rh-TFPI was added to a suspension of S. pneumoniae. Rh-TFPI reduced pneumonia-induced coagulation; rh-TFPI with ceftriaxone further attenuated coagulation relative to ceftriaxone alone. Rh-TFPI inhibited accumulation of neutrophils in lung tissue and reduced the levels of several cytokines and chemokines in lungs and plasma in mice not treated with antibiotics; in these animals, rh-TFPI initiated 24 h after infection decreased pulmonary bacterial loads. In vitro, rh-TFPI also inhibited growth of S. pneumoniae. Therapeutic rh-TFPI attenuates coagulation, inflammation and bacterial growth during pneumococcal pneumonia, whereby the latter two effects only become apparent in the absence of concurrent antibiotic treatment.

Clinical Study Concerning the Relationship between Community-Acquired Pneumonia and Viral Infection in Northern Thailand

The etiological agents associated with community-acquired pneumonia (CAP) in Thailand have been studied extensively in bacterial pathogens, but not in viral pathogens. To clarify the association of viral pathogens with CAP, we conducted a comprehensive study of viral and bacterial pathogens in patients with CAP. We enrolled 119 hospitalized patients with CAP in Nakornping Hospital, Chiang Mai, Thailand between 2006 and 2008. The severity of pneumonia was classified and the risk factors for death were estimated. Bacterial and fungal pathogens were determined from specimens taken from blood and sputum, and viral pathogens were identified from nasopharyngeal specimens by RT-PCR using primers specific for 7 respiratory viruses. Overall, 29 patients were HIV-infected and 90 patients were non-HIV-infected. The microbial pathogens most commonly isolated among HIV-infected patients were: 4 Klebsiella pneumoniae, 4 Mycobacterium tuberculosis and 3 Haemophilus influenzae. Among non-HIV infected patients, predominant microbial pathogens were: 6 Pseudomonas aeruginosa, 5 Haemophilus influenzae and 4 Klebsiella pneumoniae. As for viral pathogens for CAP, influenza virus was identified from 2 HIV-infected patients and 5 non-HIV infected patients. In addition, human rhinovirus (HRV) and respiratory syncytial virus (RSV) were identified from 2 patients each among non-HIV-infected patients. Our study demonstrates that the most common viral agent was influenza virus (5%), followed by HRV (2%) and RSV (2%) among CAP patients in northern Thailand. The underlying chronic obstructive pulmonary disease (COPD) seems to be correlated with the severity of illness.

Community Acquired Pneumonia

Community-acquired pneumonia (CAP) is a major cause of morbidity, of mortality, and of expenditure of medical resources. The etiology and antimicrobial susceptibility of CAP pathogens can differ by country. Treatment guidelines need to reflect the needs of individual countries based on pathogen susceptibility studies. Recent treatment guidelines for CAP in Korea were published by the Joint Committee of the Korean Academy of Tuberculosis and Respiratory Diseases, the Korean Society for Chemotherapy, and the Korean Society of Infectious Diseases. In this article, the etiologies, diagnoses, treatments for CAP will be reviewed and compared to the recent published Korean guidelines for CAP treatment.

Detection of Mycoplasma pneumoniae in different respiratory specimens

Mycoplasma pneumoniae (M. pneumoniae) is an important community-acquired pneumonia pathogen. Serological test and polymerase chain reaction (PCR) assay are the two main laboratory tests to detect M. pneumoniae now. Little information was compared about the sensitivity and specificity of PCR using different specimens including bronchoalveolar lavage (BAL) and nasopharyngeal aspirate (NPA). The aim of the present study was to evaluate diagnostic values of different specimens by fluorescence quantitative real-time PCR and to find clinical features helpful to diagnose M. pneumoniae pneumonia (MPP). Four hundred and six hospitalized pneumonia children were studied. M. pneumoniae DNA in NPA and BAL samples were detected by fluorescence quantitative real-time PCR. M. pneumoniae-specific IgM was tested by ELISA. MPP were diagnosed based on positive M. pneumoniae-specific IgM in 101 (24.9%) children. The median ages of MPP and non-MPP children were 4.1 and 2.4 years, respectively, with significant difference between them (p < 0.001). Laboratory results including leukocyte count, neutrophil percentage, immunoglobulins, except serum IgM, subgroups of T lymphocyte, and BAL cell count had no significant differences in MPP and non-MPP. BAL macrophage cell percentage was lower in BAL-PCR positive children (p = 0.003), while BAL neutrophil percentage was higher in BAL-PCR positive children (p = 0.007). PCR from NPA and BAL were similar in diagnostic parameters, including sensitivity, specificity, PPV, and NPV (78.6%, 63.4%, 39.8%, and 90.6% for NPA-PCR, respectively; 70.3%, 58.7%, 36.0%, and 85.6% for BAL-PCR, respectively). NPA is better than BAL as PCR sample in MPP diagnosis for similar performance in PCR assay, cheap, and less invasive. BAL is useful in defining local inflammatory condition. Age is the only prefigurative factor in MPP.

Human parainfluenza virus type 3 (HPIV 3) viral community-acquired pneumonia (CAP) mimicking swine influenza (H1N1) during the swine flu pandemic

Background The swine influenza (H1N1) pandemic began in Mexico in 2009 and quickly spread worldwide. During the H1N1 pandemic, many patients were admitted to the Winthrop-University Hospital with influenza-like illnesses (ILIs). Many hospitalized adults had H1N1 pneumonia diagnosed by laboratory or clinical criteria. However, the laboratory diagnosis of H1N1 was problematic. The rapid influenza (QuickVue A/B [Quidel, San Diego, CA]) test frequently showed false-negative results. Reverse transcriptase-polymerase chain reaction (RT-PCR), the definitive test for H1N1, was restricted or unavailable, or results were reported after they were clinically relevant. Because of difficulties making a laboratory diagnosis of H1N1, Winthrop-University Hospital’s Infectious Disease Division developed clinical criteria to diagnose H1N1 when rapid influenza diagnostic test (RIDT) results were negative. It also became clear that some patients with negative RIDT and RT-PCR H1N1 clearly had H1N1 pneumonia on a clinical basis. There have been patients who died of H1N1 pneumonia with negative RIDT and RT-PCR H1N1 but had postmortem lung specimens positive for H1N1 by RT-PCR. Methods During the flu pandemic, the main diagnostic and infection control problems were to differentiate ILIs from H1N1. Unlike admitted adults hospitalized with ILIs, clinical H1N1 pneumonia patients with negative RIDT results but had dry cough, myalgias, temperatures greater than 102°F, and a negative chest x-ray without focal segmental/lobar infiltrates. With the use of the Winthrop-University Hospital’s Infectious Disease Division diagnostic H1N1 triad, patients with H1N1 had the above plus 3 of the following 4 laboratory abnormalities: relative lymphopenia, thrombocytopenia, elevated serum transaminases, or elevated creatine phosphokinase. It was important to rapidly and accurately diagnose H1N1 to place such patients on proper precautions and initiate oseltamivir therapy. Results As the H1N1 pandemic progressed, it became clear that there were some infectious diseases that mimicked H1N1 pneumonia (eg, Legionnaires’ disease). We describe the case of a 61-year-old man who presented with an ILI with dry cough, fever, myalgias, and shortness of breath. His rapid influenza A test result was negative, and specimens for RT-PCR for H1N1 were ordered. On admission, he had relative lymphopenia, thrombocytopenia, and an elevated creatine phosphokinase. His chest x-ray showed no focal segmental or lobar infiltrates. The patient was placed on influenza precautions and administered oseltamivir. During the patient’s hospital course, the RT-PCR for H1N1 was reported negative. His respiratory fluorescent antibody viral panel was negative for influenza A, influenza B, metapneumoviruses, respiratory syncytial virus, and adenoviruses but positive for human parainfluenza virus type 3 (HPIV 3). Conclusions Clinicians should be aware of other causes of community-acquired pneumonia that may mimic H1N1 pneumonia. In our experience, the most common mimics of H1N1 pneumonia are Legionnaires’ disease or HPIV 3 in adults, and metapneumovirus or respiratory syncytial virus in children. In adult patients who present with an ILI and negative RIDT results, we suggest that respiratory secretions specimens be obtained for respiratory fluorescent antibody viral testing pending RT-PCR for H1N1 results. HPIV 3, known to be an important community-acquired pneumonia pathogen in transplant recipients and immunosuppressed patients, is also an important pathogen in immunocompetent adults. In normal adult hosts, the clinical presentation of HPIV 3 pneumonia may clinically closely mimic H1N1 pneumonia.

Atypical pathogens in adult patients admitted with community-acquired pneumonia

To investigate the current status of atypical pathogen associated infections in community-acquired pneumonia (CAP) in adults, and their clinical attributes. Clinical data, sputum specimens from acute phase, and paired sera from acute- and convalescent-phases of CAP in 153 adult patients were collected from May 2005 to May 2008 in multiple medical centers. Chlamydia pneumoniae (Cpn) IgG antibody, and Legionella pneumophila (LP) mixed IgG, IgA and IgM antibodies were determined by indirect immuno-fluorescent assay. Mycoplasma pneumoniae (Mpn) mixed IgG, IgA and IgM antibodies were determined by passive agglutination assay. All the sputum specimens were routinely cultured for bacterial isolation. Fifty-two (34%) out of the 153 cases were diagnosed as atypical CAP per the paired serum-antibody assay. Forty-seven of the 52 atypical CAP cases were infected by one atypical pathogen, 38 with Cpn, 4 with Mpn, and 5 with LP, while 5 out of the 52 atypical CAP cases were infected by 2 pathogens, Cpn and Mpnin 2, Cpn and LP in 3 cases. Eleven cases (21.2%) out of the 52 patients with atypical pneumonia were complicated with bacterial infection. Except peripheral white blood count was significant increased in the group of typical (bacterial only) pneumonia (WBC > 10 × 10⁹)/L, P = 0.03), all the other clinical parameters did not show statistically significant difference between the typical and the atypical pneumonia groups. Our data suggest that Chlamydia pneumoniae, Mycoplasma pneumoniae and Legionella pneumophila are common pathogens of adult CAP. Chlamydia pneumoniae might be the most frequent atypical pathogen associated with atypical CAP.

Evolving trends in Streptococcus pneumoniae resistance: implications for therapy of community-acquired bacterial pneumonia

Pneumonia is a major infectious disease associated with significant morbidity, mortality and utilisation of healthcare resources. Streptococcus pneumoniae is the predominant pathogen in community-acquired pneumonia (CAP), accounting for 20–60% of bacterial cases. Emergence of multidrug-resistant S. pneumoniae has become a significant problem in the management of CAP. Although pneumococcal conjugate vaccine usage in children has led to significant decreases in morbidity and mortality due to S. pneumoniae in all age groups, disease management has been further complicated by the unexpected increase in resistant serotypes, such as 19A, in some regions. Until rapid and accurate diagnostic tests become available, initial treatment of CAP will remain empirical. Thus, selection of appropriate antimicrobial therapy for CAP must be based on prediction of the most likely pathogens and their local antimicrobial susceptibility patterns. This article reviews information on antimicrobial resistance patterns amongst S. pneumoniae and implications for managing CAP.