Life-threatening hemoptysis in adults with community-acquired pneumonia due to Panton-Valentine leukocidin-secreting Staphylococcus aureus

Staphylococcus aureus Pneumonia in Can Tho, Vietnam: Clinical Characteristics, Antimicrobial Resistance Profile and Risk Factors of Mortality

INTRODUCTION

Staphylococcus aureus (S. aureus) is an important pathogen in both community-acquired and hospital-acquired pneumonia. S. aureus pneumonia has a high mortality rate and serious complications. Resistance to multiple antibiotics is a major challenge in the treatment of S. aureus pneumonia. Understanding the antibiotic resistance profile of S. aureus and the risk factors for mortality can help optimize antibiotic regimens and improve patient outcomes in S. aureus pneumonia.

METHODS

A prospective cohort study of 118 patients diagnosed with S. aureus pneumonia between May 2021 and June 2023 was conducted, with a 30-day follow-up period. Demographic information, comorbidities, Charlson Comorbidity Index, clinical characteristics, outcomes, and complications were collected for each enrolled case. The data were processed and analyzed using R version 3.6.2.

RESULTS

S. aureus pneumonia has a 30-day mortality rate of approximately 50%, with complication rates of 22% for acute respiratory distress syndrome (ARDS), 26.3% for septic shock, and 14.4% for acute kidney injury (AKI). Among patients with methicillin-resistant S. aureus (MRSA) pneumonia treated with vancomycin (n = 40), those with a vancomycin minimum inhibitory concentration (MIC) ≤ 1 had significantly higher cumulative survival at day 30 compared to those with MIC ≥ 2 (log-rank test p = 0.04). The prevalence of MRSA among S. aureus isolates was 84.7%. Hemoptysis, methicillin resistance, acidosis (pH < 7.35), and meeting the Infectious Diseases Society of America/American Thoracic Society (IDSA/ATS) criteria for severe pneumonia were significantly associated with mortality in a multivariate Cox regression model based on the adaptive least absolute shrinkage and selection operator (LASSO).

CONCLUSIONS

S. aureus pneumonia is a severe clinical condition with high mortality and complication rates. MRSA has a high prevalence in Can Tho City, Vietnam. Hemoptysis, methicillin resistance, acidosis (pH < 7.35), and meeting the IDSA/ATS criteria for severe pneumonia are risk factors for mortality in S. aureus pneumonia.

Molecular Epidemiology of Community-Acquired Methicillin-Resistant Staphylococcus aureus and Clinical Characteristics of Different Sites of Infection

Purpose

Since community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized, the molecular epidemiology of CA-MRSA in China has been diverse. It is unclear whether different sites of CA-MRSA infection differ in antimicrobial resistance and clinical characteristics. The purpose of this study was to identify the molecular types, virulence factors and antimicrobial resistance of CA-MRSA strains and to analyze the clinical characteristics of different sites of CA-MRSA infection.

Methods

26 CA-MRSA strains were screened from Beijing Chao-Yang Hospital from 2014 to 2022. SCCmec type, MLST type, spa type, Panton-Valentine leukocidin (PVL), hemolysin α (Hla), phenolic soluble regulatory protein α (PSMα), toxic shock syndrome toxin-1 (TSST-1), and enterotoxin (SE) A to E were detected by PCR and gene sequencing. Antimicrobial susceptibility tests and the clinical features of CA-MRSA infection cases were collected for statistical analysis.

Results

The predominant type of CA-MRSA was ST59-t437-IV. New non-epidemic types, SCCmec VII, were also found. PVL was seen in 65.4% of CA-MRSA strains and TSST-1 was only be detected in 3.8% of CA-MRSA strain which caused poor prognosis. There were three types of infections: pneumonia (61.5%), infective endocarditis (7.7%), and skin and soft tissue infections (SSTIs) (30.8%). CA-MRSA pneumonia cases were secondary to influenza infection (37.5%). Patients with CA-MRSA-associated infective endocarditis were more likely to have underlying cardiac diseases. Patients with CA-MRSA-associated SSTIs were more likely to have a history of diabetes mellitus, and strains in this group were more susceptible to erythromycin and clindamycin.

Conclusion

ST59-t437-IV was the primary CA-MRSA type in our research and in China. We proposed that TSST-1 might be one of the indicators to predict the severity and prognosis of CA-MRSA infection. Different sites of CA-MRSA infection had difference in antibiotics susceptibility testing and underlying diseases of patients. It could provide a new perspective on treating different types of CA-MRSA infection.

Diffuse alveolar hemorrhage in infants: Report of five cases

Diffuse alveolar hemorrhage (DAH) is a rare life-threatening condition in children. In this entity, the bleeding originates from the pulmonary microvasculature as a result of microvascular damage leading to blood leakage into the alveolar spaces. DAH can occur as an isolated medical entity or may be associated with other organ system injury or dysfunction. The classic triad of symptoms includes hemoptysis, anemia and diffuse pulmonary infiltrates. Hemoptysis is the usual presenting symptom but is not constant. A variety of diseases is associated with the development of DAH. Current classification organize the etiologies of diffuse alveolar hemorrhage based on the presence of severe immune disorders (such as systemic vasculitis and collagenosis) or non-immunodeficiency disorders (with an identified cardiac or non-cardiac origin, or idiopathic). The five cases of DAH presented in this study were all diagnosed in full-term infants, four males and one female, with normal neonatal adaptation and without family history of notable diseases. In all cases the diagnosis was made between the age of three and eighteen weeks-old. Moreover, all five patients, at the time of diagnosis, presented with hemoptysis, mild or severe dyspnea, anemia and abnormal chest X-rays. Consequently, the diagnosis of DAH was strongly suspected and, eventually, confirmed by bronchoscopy. Additional laboratory tests, as well as selected serologic and radiographic studies were performed in order to identify a specific etiology. The final diagnoses reflect a variety of causes: infections, idiopathic pulmonary hemosiderosis, accidental suffocation and Heiner syndrome. Treatment included oral corticosteroids except from one patient that received antimicrobial therapy.

[Pulmonary hemorrhage in rheumatic diseases]

In the article, we report the causes of pulmonary hemorrhage (PH) according to the literature data and own experience, with an emphasis on patients suffering from rheumatic diseases. Methods of diagnosis and modern approaches to the treatment of PH are analyzed.

Potential Factors Affected Safety and Efficacy of Transcatheter Plug Closure for Pediatric Hemoptysis with Anomalous Bronchial Arteries

OBJECTIVE

To evaluate the safety and efficacy of interventional care in pediatric hemoptysis for anomalous bronchial arteries (BAs) and to identify the potential factors resulting in hemoptysis recurrence.

METHODS

20 children complained of hemoptysis were diagnosed with anomalous BAs. All patients received transcatheter plug occlusion in Department of Cardiology, Children's Hospital of Chongqing Medical University. The safety and efficacy were evaluated according to clinical symptoms and images monitoring of enrolled subjects grouped as recurrence group and nonrecurrence group. The potential factors causing hemoptysis recurrence were reviewed and summarized.

RESULTS

No deaths were recorded in a follow-up. Otherwise, hemoptysis recurrence was found in 8 subjects for 14 times, accounting for about 40%. Compared with nonrecurrence group, it indicated a statistical significance in hemoglobin levels (P=0.049), mycoplasma pneumonia particle assays (MP-PA) titers (P=0.030), and number of anomalous BAs (P=0.020). Meanwhile, 50% recurrent scenarios were associated with a respiratory infection by microbiological assessment before transcatheter plug occlusion. The repeat occlusion was applied for unclosed BAs leading to visual recurrent hemoptysis, the average interval time of which was 5.4 ± 3.6 mon.

CONCLUSION

The data from this retrospective study have shown that transcatheter plug occlusion is a relatively safe procedure with a low mortality. The number of abnormal BAs has been identified as a highly significant predictor of recurrence, and the role of MP and other potential factors should be verified in a multicenter, larger sample size, and randomized controlled trial.

The prevalence of complications of pneumonia among adults admitted to a tertiary care center in Riyadh from 2010-2017

BACKGROUND

Pneumonia, the commonest lower respiratory tract infection, can result in respiratory and non-respiratory complications. Few studies have reported on the prevalence of many complications.

OBJECTIVES

Identify the prevalence of 18 complications of pneumonia and compare complication rates by age group and type of pneu.monia. Identify most prevalent comorbidities, the effect of the number of comorbidities on the presence of complications, and the association between specific comorbidities and specific complications.

DESIGN

Retrospective, cross-sectional prevalence study.

SETTING

Tertiary care center in Riyadh.

PATIENTS AND METHODS

The target population were patients aged 17 years and older, of different nationalities and both genders, diagnosed with pneumonia during the period of 2010 to 2017. Selection was by stratified sampling by year of admission.

MAIN OUTCOME MEASURES

Complications of pneumonia.

SAMPLE SIZE

800.

RESULTS

Complications were observed in 427 patients (53.4%). The complications were respiratory in 258 patients (32%), sepsis and septic shock in 186 (23%), cardiac in 125 (16%), neurological in 5 (0.6%), and cholestatic jaundice in 2 (0.3%). Pleural effusion was the commonest complication, observed in 230 patients. There was a significant difference (P less than .001) between the complication rates in older patients compared to younger (60% as compared to 41%). For the type of pneumonia, there was a significant difference (P less than .001) between community-acquired pneumonia and hospital-acquired pneumonia in the presence of complications (OR=2.41, 95% CI for OR=1.66, 3.49). The number of comorbidities was significantly associated with the presence of complications (P=.001) for those with multiple comorbidities (46% for patients with no comorbid illnesses versus 68% in patients with three or more comorbidities).

CONCLUSION

These results suggest that Saudi Arabia needs to establish better prevention and intervention programs, especially for the high-risk groups identified in this study: older patients, patients with hospital-acquired pneumonia and patients with two or more comorbidities.

LIMITATIONS

Retrospective design and single-centered.

CONFLICT OF INTEREST

None.

Severe Hemoptysis Associated with Bacterial Pulmonary Infection: Clinical Features, Significance of Parenchymal Necrosis, and Outcome

PURPOSE

Severe hemoptysis (SH) associated with non-tuberculosis bacterial lower respiratory tract infection (LRTI) is poorly described, and the efficacy of the usual decision-making process is unknown. This study aimed at describing the clinical, radiological patterns, mechanism, and microbiological spectrum of SH related to bacterial LRTI, and assessing whether the severity of hemoptysis and the results of usual therapeutic strategy are influenced by the presence of parenchymal necrosis.

METHODS

A single-center analysis of patients with SH related to bacterial LRTI from a prospective registry of consecutive patients with SH admitted to the intensive care unit of a tertiary referral center between November 1996 and May 2013.

RESULTS

Of 1504 patients with SH during the study period, 65 (4.3%) had SH related to bacterial LRTI, including non-necrotizing infections (n = 31), necrotizing pneumonia (n = 23), pulmonary abscess (n = 10), and excavated nodule (n = 1). The presence of parenchymal necrosis (n = 34, 52%) was associated with a more abundant bleeding (volume: 200 ml [70-300] vs. 80 ml [30-170]; p = 0.01) and a more frequent need for endovascular procedure (26/34; 76% vs. 9/31; 29%; p < 0.001). Additionally, in case of parenchymal necrosis, the pulmonary artery vasculature was involved in 16 patients (47%), and the failure rate of endovascular treatment was up to 25% despite multiple procedures.

CONCLUSIONS

Bacterial LRTI is a rare cause of SH. The presence of parenchymal necrosis is more likely associated with bleeding severity, pulmonary vasculature involvement, and endovascular treatment failure.

Community-Acquired Pneumonia in the Asia-Pacific Region

Community-acquired pneumonia (CAP) is an important cause of mortality and morbidity worldwide. Aging population, dense urbanization, and poor access to health care make the Asia-Pacific region vulnerable to CAP. The high incidence of CAP poses a significant health and economic burden in this region. Common etiologic agents in other global regions including Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Chlamydophila pneumoniae, Staphylococcus aureus, and respiratory viruses are also the most prevalent pathogens in the Asia-Pacific region. But the higher incidence of Klebsiella pneumoniae and the presence of Burkholderia pseudomallei are unique to the region. The high prevalence of antimicrobial resistance in S. pneumoniae and M. pneumoniae has been raising the need for more prudent use of antibiotics. Emergence and spread of community-acquired methicillin-resistant S. aureus deserve attention, while the risk has not reached significant level yet in cases of CAP. Given a clinical and socioeconomic importance of CAP, further effort to better understand the epidemiology and impact of CAP is warranted in the Asia-Pacific region.

Expression of Panton-Valentine leukocidin mRNA among Staphylococcus aureus isolates associates with specific clinical presentations

Panton-Valentine leukocidin (PVL; gene designation lukF/S-PV) is likely an important virulence factor for Staphylococcus aureus (S. aureus), as qualitative expression of the protein correlates with severity for specific clinical presentations, including skin and soft tissue infections (SSTIs). Development of genetic approaches for risk-assessment of patients with S. aureus infections may prove clinically useful, and whether lukF/S-PV gene expression correlates with specific clinical presentations for S. aureus has been largely unexplored. In the present study, we quantified lukS-PV mRNA among 96 S. aureus isolates to determine whether expression levels correlated with specific clinical presentations in adults and children. Expression level of lukS-PV mRNA among isolates from skin and soft tissue infections (SSTIs) was significantly greater than among isolates from blood stream infection (BSIs), and expression level of lukS-PV mRNA among BSI isolates from children was significantly greater than for BSI isolates among adults. Moreover, expression level of lukS-PV mRNA among community-acquired (CA) isolates was significantly greater than for hospital-acquired (HA) isolates. These data justify additional studies to determine the potential clinical utility for lukS-PV mRNA quantification as a predictive tool for severity of S. aureus infection.

Severe leukopenia in Staphylococcus aureus-necrotizing, community-acquired pneumonia: risk factors and impact on survival

Background

Necrotizing pneumonia attributed to Panton-Valentine leukocidin-positive Staphylococcus aureus has mainly been reported in otherwise healthy children and young adults, with a high mortality rate. Erythroderma, airway bleeding, and leukopenia have been shown to be predictive of mortality. The objectives of this study were to define the characteristics of patients with severe leukopenia at 48-h hospitalization and to update our data regarding mortality predicting factors in a larger population than we had previously described.

Methods

It was designed as a case-case study nested in a cohort study. A total of 148 cases of community-acquired, necrotizing pneumonia were included. The following data were collected: basic demographic information, medical history, signs and symptoms, radiological findings and laboratory results during the first 48 h of hospitalization. The study population was divided into 2 groups: (1) with severe leukopenia (leukocyte count ≤3,000 leukocytes/mL, n=62) and (2) without severe leukopenia (>3,000 leukocytes/mL, n=86).

Results

Median age was 22 years, and the male-to-female gender ratio was 1.5. The overall in-hospital mortality rate was 41.2%. Death occurred in 75.8% of severe leukopenia cases with median survival time of 4 days, and in 16.3% of cases with leukocyte count >3,000/mL (P<0.001). Multivariate analysis indicated that the factors associated with severe leukopenia were influenza-like illness (adjusted odds ratio (aOR) 4.45, 95% CI (95% confidence interval) 1.67-11.88, P=0.003), airway bleeding (aOR 4.53, 95% CI 1.85-11.13, P=0.001) and age over 30 years (aOR 2.69, 95% CI 1.08-6.68, P=0.033). A personal history of furuncles appeared to be protective (OR 0.11, 95% CI 0.01-0.96, P=0.046).

Conclusion

S. aureus-necrotizing pneumonia is still an extremely severe disease in patients with severe leukopenia. Some factors could distinguish these patients, allowing better initial identification to initiate adapted, rapid administration of appropriate therapy.

Effects of linezolid on suppressing in vivo production of staphylococcal toxins and improving survival outcomes in a rabbit model of methicillin-resistant Staphylococcus aureus necrotizing pneumonia

BACKGROUND

 Linezolid is recommended for treatment of pneumonia and other invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA). The premise underlying this recommendation is that linezolid inhibits in vivo production of potent staphylococcal exotoxins, including Panton-Valentine leukocidin (PVL) and α-hemolysin (Hla), although supporting evidence is lacking.

METHODS

 A rabbit model of necrotizing pneumonia using MRSA clone USA300 was used to compare therapeutic effects of linezolid (50 mg/kg 3 times/day) and vancomycin (30 mg/kg 2 times/day) administered 1.5, 4, and 9 hours after infection on host survival outcomes and in vivo bacterial toxin production.

RESULTS

 Mortality rates were 100% for untreated rabbits and 83%-100% for vancomycin-treated rabbits. In contrast, mortality rates were 25%, 50%, and 100% for rabbits treated with linezolid 1.5, 4, and 9 hours after infection, respectively. Compared with untreated and vancomycin-treated rabbits, improved survival of rabbits treated 1.5 hours after infection with linezolid was associated with a significant decrease in bacterial counts, suppressed bacterial production of PVL and Hla, and reduced production of the neutrophil-chemoattractant interleukin 8 in the lungs.

CONCLUSIONS

 Across the study interval, only early treatment with linezolid resulted in significant suppression of exotoxin synthesis and improved survival outcomes in a rabbit model of MRSA necrotizing pneumonia.

Cystic fibrosis: management of haemoptysis

Haemoptysis is a common complication in cystic fibrosis (CF), occurring in approximately 9% of the population. Massive haemoptysis is associated with older patients, more severe disease and carries a high mortality rate. Despite this there are few robust published studies of effective treatments and knowledge of the precise pathogenesis is limited. Current guidelines for treatment from the Cystic Fibrosis Foundation (CFF) are based on consensus opinion of experts. Patients with massive haemoptysis who do not respond to initial medical treatments should undergo bronchial artery embolization. This will control the bleeding in the majority of cases but recurrence rates are high and there are little data to support long-term improved outcomes. Surgery is a last resort in patients with CF.

Frequency and clinical association of Panton-Valentine leukocidin-positive Staphylococcus aureus isolates: a study from Kuwait

OBJECTIVE

This study was undertaken to determine the frequency of Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus among strains isolated in our laboratory and to study the association of PVL-positive strains with clinical disease.

MATERIALS AND METHODS

A total of 291 S. aureus isolates obtained from different clinical specimens from June 1, 2009, to March 31, 2010, at the Farwania Hospital Laboratory were investigated for antimicrobial susceptibility, carriage of genes for PVL, and SCCmec elements. Antimicrobial susceptibility testing was performed by standard methods. The presence of mecA genes for PVL SCCmec typing was determined by PCR.

RESULTS

Of the 291 S. aureus isolates, 89 (30.6%) were methicillin-resistant S. aureus (MRSA), whereas 202 (69.4%) were methicillin susceptible (MSSA). Genes for PVL were detected in 13 (14.6%) and 24 (12.0%) of the MRSA and MSSA isolates, respectively. The majority of the PVL-producing MRSA and MSSA were isolated from 12 (30.7%) and 19 (21.8%) cases of skin and soft tissue infections (SSTI), respectively. Although both MSSA and MRSA strains were uniformly susceptible to rifampicin, teicoplanin, and vancomycin, multidrug resistance was observed among PVL-producing and nonproducing MRSA isolates. Both MRSA types carried SCCmec type III, IV, IVc, and V genetic elements.

CONCLUSION

This study revealed the presence of genes for PVL in both MSSA and MRSA, associated mostly with SSTI and respiratory tract infections, supporting previous observations that PVL production is widespread among S. aureus strains obtained from different clinical sources.

Infectious diseases causing diffuse alveolar hemorrhage in immunocompetent patients: a state-of-the-art review

Diffuse alveolar hemorrhage (DAH) represents a syndrome that can complicate many clinical conditions and may be life-threatening, requiring prompt treatment. It is recognized by the signs of acute- or subacute-onset cough, hemoptysis, diffuse radiographic pulmonary infiltrates, anemia, and hypoxemic respiratory distress. DAH is characterized by the accumulation of intra-alveolar red blood cells originating most frequently from the alveolar capillaries. It must be distinguished from localized pulmonary hemorrhage, which is most commonly due to chronic bronchitis, bronchiectasis, tumor, or localized infection. Hemoptysis, the major sign of DAH, may develop suddenly or over a period of days to weeks; this sign may also be initially absent, in which case diagnostic suspicion is established after sequential bronchoalveolar lavage reveals worsening red blood cell counts. The causes of DAH can be divided into infectious and noninfectious, the latter of which may affect immunocompetent or immunodeficient patients. Pulmonary infections are rarely reported in association with DAH, but they should be considered in the diagnostic workup because of the obvious therapeutic implications. In immunocompromised patients, the main infectious diseases that cause DAH are cytomegalovirus, adenovirus, invasive aspergillosis, Mycoplasma, Legionella, and Strongyloides. In immunocompetent patients, the infectious diseases that most frequently cause DAH are influenza A (H1N1), dengue, leptospirosis, malaria, and Staphylococcus aureus infection. Based on a search of the PubMed and Scopus databases, we review the infectious diseases that may cause DAH in immunocompetent patients.

Diffuse alveolar hemorrhage in immunocompetent patients: etiologies and prognosis revisited

BACKGROUND

Diffuse alveolar hemorrhage (DAH) represents a diagnostic challenge of acute respiratory failure. Prompt identification of the underlying cause of DAH and initiation of appropriate treatment are required in order to prevent acute respiratory failure and irreversible loss of renal function. More than 100 causes of DAH have been reported. However, the relative frequency and the differential presentation of those causes have been poorly documented, as well as their respective prognosis.

METHODS

We retrospectively reviewed the charts of 112 consecutive patients hospitalized for DAH in a tertiary referral center over a 30-year period.

RESULTS

Twenty-four causes of DAH were classified into four etiologic groups: immune (n = 39), congestive heart failure (CHF; n = 33), miscellaneous (n = 26), and idiopathic DAH (n = 14). Based on this classification, clinical and laboratory features of DAH differed on hospital admission. Patients with immune DAH had more frequent pulmonary-renal syndrome (p < 0.001), extra-pulmonary symptoms (p < 0.01), and lower blood hemoglobin level than others (p < 0.001). Patients with CHF-related DAH were older and received more anticoagulant treatments than others (p < 0.05). Those with miscellaneous causes of DAH exhibited a shorter prodromal phase (p < 0.001) and had more frequent hemoptysis >200 mL (p < 0.05). Patients with idiopathic DAH had more bronchoalveolar lavage siderophages (p < 0.01). In-hospital mortality was 24.1%, ranging from 7.1% in patients with idiopathic DAH to 36.4% in those with CHF.

CONCLUSIONS

Arbitrary classification of DAH in four etiologic groups gives the opportunity to underline distinct presentations and outcomes of various causes of DAH.

Post-influenza pneumonia caused by the USA300 community-associated methicillin-resistant Staphylococcus aureus in Korea

Panton-Valentine leukocidin (PVL)-positive USA300 clone has been the most successful community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) clone spreading in North America. In contrast, PVL-negative ST72-CA-MRSA has been predominant in Korea, and there has been no report of infections by the USA300 strain except only one case report of perianal infection. Here, we describe the first case of pneumonia caused by the USA300 strain following pandemic influenza A (H1N1) in Korea. A 50-year-old man was admitted with fever and cough and chest radiograph showed pneumonic consolidation at the right lower lung zone. He received a ventilator support because of respiratory failure. PCR for pandemic influenza A (H1N1) in nasopharyngeal swab was positive, and culture of sputum and endotracheal aspirate grew MRSA. Typing of the isolate revealed that it was PVL-positive, ST 8-MRSA-SCCmec type IV. The analysis of the PFGE patterns showed that this isolate was the same pulsotype as the USA300 strain.

Community-acquired necrotizing pneumonia due to methicillin-sensitive Staphylococcus aureus secreting Panton-Valentine leukocidin: a review of case reports

BACKGROUND

Community-acquired necrotizing pneumonia caused by Panton-Valentine leukocidin (PVL)-secreting Staphylococcus aureus is a highly lethal infection that mainly affects healthy children and young adults. Both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) may carry the PVL-phage, but the majority of publications relate to community-associated methicillin-resistant S. aureus (CA-MRSA) or mixed patient groups. This study focuses on necrotizing pneumonia due to methicillin-sensitive S. aureus strains, with the purpose to determine factors associated with outcome.

METHODS

We report a patient with PVL secreting MSSA necrotizing pneumonia and performed a systematic review of similar case in the literature. We analyzed factors associated with outcome.

RESULTS

A total of 32 patient descriptions were retained for analysis. Septic shock (p = 0.007), influenza-like prodrome (p = 0.02), and the absence of a previous skin and soft-tissue infection (p = 0.024) were associated with fatal outcome. In multivariate analysis, influenza-like prodrome (odds ratio (OR), 7.44; 95% confidence interval (CI), 1.24-44.76; p = 0.028) and absence of previous skin and soft-tissue infection (OR, 0.09; 95% CI, 0.01-0.86; p = 0.036) remained significant predictors of death.

CONCLUSIONS

Influenza-like prodrome may be predictive of adverse outcome in PVL-secreting MSSA necrotizing pneumonia. In contrast, previous skin and soft-tissue infection may be associated with improved prognosis.

Methicillin-resistant Staphylococcus aureus in a Canadian intensive care unit: Delays in initiating effective therapy due to the low prevalence of infection

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) infection in intensive care units (ICUs) has increased dramatically in prevalence in recent years, and is associated with increased morbidity, mortality and cost of care. The aim of the present study was to describe the epidemiology and outcomes of MRSA infection in the general systems ICU at the University of Alberta Hospital in Edmonton, Alberta.

METHODS

A retrospective cohort analysis of patients infected with MRSA in a general systems ICU was conducted from January 1, 1997, to August 15, 2005.

RESULTS

Forty-six cases of MRSA were identified, of which 36 (78.3%) were infected. The most common admitting diagnoses included respiratory failure (41.7%) and sepsis or septic shock (36.1%). Infection was hospital acquired in 58.3% of cases (10 cases ICU acquired), with a median time to infection of 11 days. The most common sites of infection were the respiratory tract, skin and blood. Median lengths of stay were 13 days in the unit and 27 days in-hospital. Crude mortality was 55.6%. Time to appropriate antimicrobial treatment was delayed in 80.5% of patients. Four prototypical Canadian MRSA (CMRSA) strains were identified by pulsed-field gel electrophoresis. Hospital-acquired strains were predominantly CMRSA-2 (59%), indicating that this clone circulates at the University of Alberta Hospital.

CONCLUSIONS

MRSA infection remains uncommon at the University of Alberta Hospital, resulting in delays in instituting appropriate antimicrobial therapy. To date, only a few community-acquired strains have been noted. ICU acquisition of MRSA remains rare, with only 10 cases over the past nine years. The majority of hospital-acquired strains were CMRSA-2.

Methicillin-resistant Staphylococcus aureus: a community health threat

Methicillin-resistant Staphylococcus aureus (MRSA), one of the most common causes of infections, has been traditionally recognized as a nosocomial pathogen. However, in recent years, its epidemiology has radically changed, being now observed even more frequently in the community, and accounting for > 50% of staphylococcal infections in the US outpatient setting. Community-acquired (CA)-MRSA strains typically cause infections among otherwise healthy individuals, with risk factors differing from those of nosocomial MRSA. The clinical manifestations may range from a furuncle to life-threatening infections, such as necrotizing fasciitis and pneumonia. The antibiotic treatment of these infections may also differ because CA-MRSA strains often retain susceptibility to antimicrobials other than glycopeptides and newer agents. Moreover, the production of toxins, such as the Panton-Valentine leukocidin (PVL), should influence the antibiotic choice because in these cases the use of a combination therapy with antimicrobial agents able to decrease toxin production is suggested. There are still many unanswered key questions regarding the epidemiology, prevention, and treatment of CA-MRSA infections. This article reviews current knowledge of CA-MRSA.

DNA microarray based detection of genes involved in safety and technologically relevant properties of food associated coagulase-negative staphylococci

Aim of the work was to design a polynucleotide based DNA microarray as screening tool to detect genes in food associated coagulase-negative staphylococci (CNS). A focus was laid on genes with potential health concern and technological relevance. The microarray contained 220 probes for genes encoding antibiotic resistances, hemolysins, toxins, amino acid decarboxylases (e.g. biogenic amine formation), binding proteins to extracellular matrix (ECM), lipases, proteases, stress response factors, or nitrate dissimilation. Hybridization of genomic DNA isolated from 32 phenotypically characterized CNS permitted to detect numerous genes, corresponding with the phenotype. However, numerous hybridization signals were obtained for genes without any detectable phenotype. The antibiotic resistance genes blaZ, lnuA, and tetK involved in ß-lactam, lincomycin and tetracycline resistance, respectively, were rarely identified in CNS, however, all species contained some strains with such resistance genes. Decarboxylase genes involved in biogenic amine formation were detected regularly in Staphylococcus carnosus, S. condimenti, S. piscifermentans and S. equorum, but was rarely correlated with the phenotype. The same applied for the fibrinogen (clf) and fibronectin (fbp) binding protein genes, whose phenotype (binding assay) was only correlated in S. equorum and Staphylococcus succinus. Although some CNS showed hemolytic activity and enterotoxin production (Immunoblot) the corresponding genes could not be verified. Technological relevant genes such as proteases or lipases revealed good hybridization signals. In addition, genes involved in nitrate dissimilation (nre, nar, nir), catalase (kat), or superoxide dismutase (sod) were well detected. Interestingly, genes involved in dissimilatory nitrate reduction were more prevalent in strains of S. carnosus, S. condimenti and S. piscifermentans than of S. equorum, S. succinus and S. xylosus.

Factors associated with the outcome of life-threatening necrotizing pneumonia due to community-acquired Staphylococcus aureus in adult and adolescent patients

BACKGROUND

Although community-acquired Staphylococcus aureus pneumonia with highly virulent Panton-Valentine leukocidin (PVL)-positive strains, a severe disease with significant lethality, is rare, especially in adult and adolescent patients, recent reports highlight that these infections are on the rise.

OBJECTIVES

To describe the demographic and clinical features of reported cases of life-threatening community-acquired S. aureus pneumonia with usually PVL-positive strains in adult and adolescent patients, to evaluate the variables related to death, and to select a more appropriate antimicrobial treatment for this potentially deadly disease.

METHODS

We summarized all of the 92 reported cases and our case. The effect of 5 variables on mortality was measured using logistic regression.

RESULTS

S. aureus community-acquired pneumonia (CAP) with usually PVL-positive strains is a severe disease with significant lethality, i.e. 42.9%; a short duration of the time from the onset of symptoms to death, i.e. 5.5 ± 10.1 days, and prolonged hospital admissions, i.e. 33.2 ± 29.5 days. Seventy-three cases have been tested for the gene for PVL, and 71 strains have been found to carry the PVL gene. Logistic regression analysis showed that leucopenia (p = 0.002), influenza-like symptoms or laboratory-confirmed influenza (p = 0.011), and hemoptysis (p = 0.024) were the factors associated with death. Antibiotic therapies inhibiting toxin production were associated with an improved outcome in these cases (p = 0.007).

CONCLUSIONS

Physicians should pay special attention to those patients who acquired severe CAP during influenza season and have flu-like symptoms, hemoptysis, and leucopenia, and they should consider S. aureus more frequently among the possible pathogens of severe CAP. Empiric therapy for severe CAP with this distinct clinical picture should include coverage for S. aureus. Targeted treatment with antimicrobials inhibiting toxin production appears to be a more appropriate selection.

Treatment of pulmonary exacerbations in adult cystic fibrosis patients: a review

Cystic fibrosis (CF) is a complex multisystemic disease requiring specialized care. It is characterized by progressive pulmonary decline, with intermittent worsening of lung function, often called pulmonary exacerbations. Eighty-five percent of all deaths from CF are a result of pulmonary disease, and pulmonary exacerbations are associated with decline in lung function. Treating pulmonary exacerbations requires a multifaceted approach and includes a multidisciplinary team composed of a physician, nurse, respiratory therapist, physical therapist, and nutritionist. Recently, the Cystic Fibrosis Foundation published guidelines addressing the comprehensive treatment of pulmonary exacerbations. This article outlines the treatment goals established by these guidelines, including the evaluation and treatment of comorbid conditions (eg, CF-related diabetes) and serious complications associated with CF exacerbations (eg, pneumothorax). Proper treatment of pulmonary exacerbations in CF patients will continue to improve their health and quality of life.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Prevalence of Genes Encoding Bi-Component Leukocidins among Clinical Isolates of Methicillin Resistant Staphylococcus aureus

BACKGROUND

Staphylococcus aureus has been recognized as a major human pathogen and is the major cause of nosocomial infections. Gamma-toxin, leukocidin and other bi-component toxins are a family of proteins encoded by the hlg and luk-PV, respectively. Panton-Valentine leukocidin (PVL) is an example of these toxins and causes leukocyte destruction and tissue necrosis. The aim of this study was to determine the prevalence of bi-component leukocidin in Methicillin Resistant Staphylococcus aureus (MRSA) isolates in staphylococcal infections.

METHODS

Collectively, 143 isolates of S. aureus were obtained from Tehran University of Medical Sciences hospitals and confirmed with biochemical tests. Then polymerase chain reaction was used to detect luk-PV loci and luk-E/D. Coagulase gene was used as internal control. The antibiotic susceptibility patterns of isolates were determined using disk diffusion method.

RESULTS

Out of 149 S. aureus isolates 24.2% were luk-PV positive and 73.8% were luk-E/D positive.

CONCLUSION

There was PVL positive MRSA isolates with high prevalence in evaluated hospitals. The diseases from these bacteria are with extensive necrosis, leucopenia and even death. We desire that, prevent from progress and death by diagnosis and right treatment.

Five cases of bacterial endocarditis after furunculosis and the ongoing saga of community-acquired methicillin-resistant Staphylococcus aureus infections

Bacterial endocarditis secondary to Panton-Valentine leukocidin producing community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections is rare. We report 5 previously healthy patients who presented with endocarditis after developing furunculosis due to CA-MRSA. A retrospective chart review of all patients with MRSA positive blood cultures was conducted over a 12-month period. Patients with multiple positive blood cultures within 72 h of admission and who had no risk factors for MRSA acquisition were included. Modified Duke's criteria were used to define bacterial endocarditis. PCR detection of Panton-Valentine leukocidin (PVL) genes as well as SCCmec typing was performed. In addition, strain typing of MRSA isolates was performed utilizing pulsed-field gel electrophoresis. Five out of a total of 193 patients had features consistent with CA-MRSA infections and met modified Duke's criteria for bacterial endocarditis. Blood culture isolates were found to be PVL gene positive and carried the type IV SCCmec element. PFGE confirmed that skin isolate was identical to the isolate cultured from his blood. Bacterial endocarditis in patients with CA-MRSA furunculosis is an emerging entity. In areas where CA-MRSA skin infections are prevalent, inappropriate initial antibiotics remain a major problem and may result in significant morbidity.

Fatal Staphylococcus aureus haemorrhagic pneumonia producing Panton-Valentine leucocidin

We present 2 cases of community acquired S. aureus pneumonia carrying Panton Valentine leucocidin (PVL). These cases illustrate this clinical entity characterized by a younger and healthier population than usual staphylococcal pneumonias and complicated by a 75% mortality rate. We also discuss the diagnosis and therapeutic difficulties.

Aetiology, diagnosis and management of infective causes of severe haemoptysis in intensive care units

PURPOSE OF THE REVIEW

Infective causes of severe haemoptysis have progressively shifted to causes related to chronic inflammatory lung diseases. Physicians should, however, recognize the most common of them, for example necrotizing parenchymal infections, tuberculosis and mycetoma.

RECENT FINDINGS

The recent increase in the incidence of a devastating Panton-Valentine leukocidin-associated staphylococcal pneumonia has reminded us of the crucial role of prompt diagnosis and management. General supportive care should be administered to prevent asphyxiation in addition to starting appropriate antibiotics as soon as possible. Once the bleeding has been controlled, the diagnostic strategy should integrate a detailed medical history, physical examination, Gram stain of the respiratory specimens and chest radiograph. Computed tomography scan has dramatically improved the diagnosis and the treatment of infective causes of severe haemoptysis by assessing the cause and mechanism(s) of haemoptysis. Although bronchial arteries are the major source of bleeding, nonbronchial systemic and pulmonary arteries' involvement should be feared, especially in haemoptysis related to tuberculosis and mycetoma.

SUMMARY

Endovascular therapy should be first attempted to control the bleeding and then elective surgery performed in case of localized lesion and adequate pulmonary function. Fibreoptic bronchoscopy with broncho-alveolar lavage remains the cornerstone of diagnosis in immunocompromised hosts with haemoptysis and in the rare cases of alveolar haemorrhage related to infectious diseases.

Panton-Valentine Leukocidin associated with community acquired methicillin resistant Staphylococcus aureus: a case report and review of interim guidelines

We report a case of community acquired methicillin resistant Staphylococcus aureus pneumonia. The causative organism was positive for the toxin Panton-Valentine Leukocidin. This resulted in a severe pneumonia requiring a prolonged stay on our intensive care unit. This infection is becoming more common in the United Kingdom. It can cause a far more aggressive illness than the hospital acquired infection with a high mortality if it becomes an invasive infection. The Department of Health has recently produced interim guidelines for its treatment which we have also reviewed.

Community-associated methicillin-resistant Staphylococcus aureus

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged over the last decade across the United States and the world, becoming a major pathogen in many types of community-acquired infections. Although most commonly associated with minor skin and soft tissue infections, such as furuncles, CA-MRSA also can cause necrotizing fasciitis, pyomyositis, osteoarticular infections, and community-acquired pneumonia. This article discusses the epidemiology, diagnosis, and management of these infections from the perspective of the emergency physician.

Toxigenicity in Staphylococcus aureus and Coagulase-Negative Staphylococci: Epidemiological and Molecular Aspects

Representatives of the Staphylococcus genus are the most common pathogens found in hospital environments, and they are etiological agents for a large variety of infections. Various virulence factors are responsible for the symptoms and severity of infections caused by Staphylococcus aureus. Among them are staphylococcal enterotoxins (SEs), which cause staphylococcal food poisoning, and toxic shock syndrome toxin-1 (TSST-1). Some reports indicate that TSST-1 and staphylococcal enterotoxins are also produced by coagulase-negative staphylococci (CNS). The present review aimed to discuss general aspects of staphylococcal toxins as well as the epidemiology, genetics and detection of toxins in Staphylococcus aureus and coagulase-negative staphylococci, since these microorganisms are becoming more and more frequent in nosocomial infections.

Pulmonary complications in adult patients with cystic fibrosis

Early diagnosis, treatments of acute exacerbations, and chronic therapies have all improved the lifespan of cystic fibrosis patients; however, the natural history remains one of worsening bronchiectasis and obstructive airways impairment. The progression of disease leads to eventual respiratory failure, but some will have other acute respiratory complications that require intervention. In this report, we review the most common life-threatening respiratory complications of cystic fibrosis, including pneumothorax, massive hemoptysis, and respiratory failure.

Community-associated CMRSA-10 (USA-300) is the predominant strain among methicillin-resistant Staphylococcus aureus strains causing skin and soft tissue infections in patients presenting to the emergency department of a Canadian tertiary care hospital

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen first described among individuals with no contact with health care facilities. The purpose of this study was to determine the proportion of CA-MRSA, defined by pulsed field gel electrophoresis (PFGE), in MRSA skin and soft tissue infections presenting to the Emergency Department (ED). We also aimed to describe the laboratory and clinical characteristics of CA-MRSA infections. From June 1, 2001 to May 30, 2005, MRSA isolates from skin and soft tissue infections presenting to the ED were reviewed. They were characterized by antibiotic susceptibilities and PFGE, and the presence of staphylococcal cassette chromosome (SCC) mec type IVa and Panton-Valentine leukocidin (PVL) genes was assessed on representative isolates. The medical records were reviewed to define risk factors. There were 95 isolates available for analysis, of which 58 (61%) were CMRSA-10 (USA-300), the predominant clone from 2003 onward. All representative isolates (24%) tested in this group had PVL genes and SCCmec type IVa. Their antibiogram showed 100% susceptibility to trimethoprim-sulfamethoxazole, rifampin, and fusidic acid, and 79% to clindamycin. Clinical comparison of CMRSA-10 vs. hospital PFGE type strains showed 22% vs. 60%, respectively, for recent antibiotic use (p < 0.0001), 26% vs. 6%, respectively, for intravenous drug use (p < 0.05), and 57% vs. 6%, respectively, for soft tissue abscess (p < 0.001). CMRSA-10 is a major pathogen in skin and soft tissue abscesses in our ED. It has a characteristic susceptibility, and was associated with intravenous drug use, but not with recent antibiotic usage.

Diagnosis and treatment of Panton–Valentine leukocidin (PVL)-associated staphylococcal pneumonia

Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus is emerging as a serious problem worldwide. Whilst usually causing skin and soft-tissue infections, particularly recurrent abscesses, there has in the last 10 years been an increase in the incidence of an associated devastating pneumonia affecting previously healthy young people and associated with a very high mortality. There are no evidence-based guidelines to consult for the management of PVL-associated staphylococcal pneumonia. The literature contains less than 100 cases, with widely differing antimicrobial therapies and the occasional use of other adjunctive therapies such as intravenous immunoglobulin, activated protein C and extracorporeal membrane oxygenation. This literature review focuses on the salient features of diagnosis and management, with particular attention to the choice of antimicrobials.

Factors Predicting Mortality in Necrotizing Community-Acquired Pneumonia Caused by Staphylococcus aureus Containing Panton-Valentine Leukocidin

BACKGROUND

Necrotizing pneumonia due to Panton-Valentine leukocidin-producing strains of Staphylococcus aureus is associated with a high mortality rate. We sought factors associated with vital outcome in 50 cases occurring from 1986 through 2005.

METHODS

We compared the clinical and biological characteristics of 50 patients according to their vital outcome and examined the characteristics of the corresponding S. aureus isolates.

RESULTS

The overall mortality rate was 56%, and the median survival time was 10 days. All of the deaths were attributed to S. aureus infection and were secondary to refractory shock and/or respiratory failure. Fatal outcome was associated with classical severity factors, such as the need for mechanical ventilation or inotrope support, and with onset of the acute respiratory distress syndrome. Airway bleeding was strongly associated with fatal outcome (P=.002). Patients who had focal staphylococcal infection before the onset of pneumonia had a significantly lower mortality rate (P=.002). The main biological feature associated with death was leukopenia (P<.001). In multivariate analysis, leukopenia and erythroderma occurring within the first 24 h after admission to the hospital were independently associated with fatal outcome. Erythroderma was not associated with toxic shock syndrome toxin.

CONCLUSIONS

Airway bleeding, erythroderma, and leukopenia are associated with fatal outcome from Panton-Valentine leukocidin-positive S. aureus necrotizing pneumonia. More work is needed to develop more efficacious therapy against this highly lethal disease.

Comparative genomics and DNA array-based genotyping of pandemic Staphylococcus aureus strains encoding Panton-Valentine leukocidin

Within the last few years, methicillin-resistant Staphylococcus aureus (MRSA) strains encoding Panton-Valentine leukocidin (PVL) have emerged and spread worldwide. This epidemic can be attributed to a small number of distinct clones. The present study used a novel assay, based on multiplex linear DNA amplification and subsequent microarray hybridisation, to simultaneously detect all relevant exotoxins, antimicrobial resistance determinants and the allelic variants of agr. The genes of the staphylococcal exotoxin-like (set) locus were also included for typing purposes. This assay, together with multilocus sequence typing (MLST) and spa typing, was applied to 56 clinical isolates and reference strains representing all major pandemic PVL-MRSA lineages, as well as to phylogenetically-related strains and putative ancestors. Array hybridisation results allowed the assignment of isolates to clonal groups, which were in accordance with MLST and spa typing data. Ten distinct clonal groups of PVL-MRSA (ST1, ST5, ST8, ST22, ST30, ST59/359, ST80/583, ST88, ST93 and ST152), including 12 MLST types, were identified and analysed with regard to resistance determinants and genes coding for exotoxins. The array hybridisation data confirmed that pandemic PVL-positive strains originate from very diverse genetic backgrounds, and provided insights into the evolution of some lineages. The DNA microarray technique provides a valuable epidemiological tool for the detailed characterisation of clinical isolates and comparison of strains at a global level.

Microarray-based characterisation of a Panton-Valentine leukocidin-positive community-acquired strain of methicillin-resistant Staphylococcus aureus

Recent years have witnessed the emergence of novel methicillin-resistant Staphylococcus aureus (MRSA) strains that produce the potent toxin Panton-Valentine leukocidin (PVL). PVL-positive strains can cause complicated skin infections or necrotising pneumonia with high mortality, and these strains have the potential for epidemic spread in the community. In 2004-2005, two case clusters and two isolated cases were observed in eastern Saxony and southern Brandenburg. These were the first known infections with PVL-positive community-acquired MRSA (caMRSA) in this part of Germany. The isolates belonged to agr type III, spa type 44 or spa type 131, and showed a SmaI macrorestriction pattern that corresponded to caMRSA of clonal group ST80. The isolates were susceptible to levofloxacin, macrolides, clindamycin, gentamicin and vancomycin. Most isolates showed resistance to tetracycline and fusidic acid because of the presence of the tetK and far1 genes. A novel plasmid (designated pUB102) harbouring far1, tetK and blaZ was characterised and partially sequenced. Microarray analysis revealed that the caMRSA isolates harboured genes encoding several bi-component toxins (lukF/S-PVL, lukD/E, lukS/F plus hlgA, and another putative leukocidin homologue). Neither tst1 nor genes for enterotoxins A-Y were detected, but the isolates harboured several staphylococcal enterotoxin-like toxin genes (set genes), as well as genes encoding an epidermal cell differentiation inhibitor (edinB) and exfoliative toxin D (etD). Comparative analysis of other isolates from Australia, Germany, Switzerland and the UK showed that these isolates were representative of a widespread clone of caMRSA.

Therapies and vaccines for emerging bacterial infections: learning from methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging bacterial infection worldwide, and community-acquired MRSA (CA-MRSA) infection, which has increased dramatically in frequency in many areas, is of particular clinical and public health concern. CA-MRSA outbreaks and severe infections have been reported more frequently in children, often manifesting in one of two distinct clinical syndromes, furunculosis or necrotizing pneumonia. This article outlines the molecular biology of MRSA, how molecular biology has contributed to the understanding of MRSA infections, current therapy and prevention of MRSA, and the prospects for a vaccine against S aureus.

[Staphylococcus aureus infections: new challenges from an old pathogen]

Staphylococcus aureus is a versatile organism with several virulent characteristics and resistance mechanisms at its disposal. It is also a significant cause of a wide range of infectious diseases in humans. S. aureus often causes life-threatening deep seated infections like bacteremia, endocarditis and pneumonia. While traditionally confined mostly to the hospital setting, methicillin-resistant S. aureus (MRSA) is now rapidly becoming rampant in the community. Community-acquired MRSA is particularly significant because of its potential for unchecked spread within households and its propensity for causing serious skin and pulmonary infections. Because of the unfavorable outcome of many MRSA infections with the standard glycopeptide therapy, new antimicrobial agents belonging to various classes have been introduced and have been evaluated in clinical trials for their efficacy in treating resistant staphylococcal infections. A number of preventive strategies have also been suggested to contain the spread of such infections. In this review, we address the recent changes in the epidemiology of S. aureus and their impact on the clinical manifestations and management of serious infections. We also discuss new treatment modalities for MRSA infections and emphasize the importance of preventive approaches.