Ventilator-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) Pneumonia in a Patient with a Negative MRSA Nasal Swab

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is associated with high morbidity and mortality. Recently, MRSA testing by nasal swab has been utilized to "exclude" pneumonia caused by MRSA, given its high negative-predictive value (NPV). We present, however, a case of MRSA pneumonia diagnosed by endotracheal aspirate culture (EAC) in a patient with a negative MRSA nasal swab. CASE REPORT A 58-year-old woman presented with septic shock and respiratory failure. Chest X-ray (CXR) on admission was unrevealing; however, computed tomography (CT) revealed multifocal pneumonia. Intensive Care Unit (ICU)-level care was required for mechanical ventilation and vasopressors. She initially improved with treatment of community-acquired pneumonia (CAP) and was extubated on hospital day 6; however, she then developed a fever, tachycardia, and respiratory distress necessitating re-intubation later that day. Repeat CXR demonstrated a new left lower lobe infiltrate. Blood cultures were drawn and vancomycin and cefepime were started to cover for ventilator-associated pathogens. An EAC and nasal swab were collected to test for MRSA. The next day (day 7), the MRSA nasal swab returned negative, and vancomycin was discontinued. Our patient continued to experience fevers, worsening leukocytosis, and ongoing vasopressor need. On hospital day 9, the EAC results were obtained, and were positive for MRSA. Vancomycin was restarted and our patient recovered. CONCLUSIONS Negative MRSA nasal screening may be considered grounds to de-escalate empiric MRSA antibiotics if MRSA prevalence is low. However, in critically ill patients with high risk and suspicion for MRSA pneumonia, discontinuing empiric MRSA coverage should be done with caution or clinicians should wait until respiratory culture results are obtained before de-escalating antibiotics.

Association of Staphylococcus aureus Colonization and Pneumonia in the Intensive Care Unit

IMPORTANCE

Carriage of Staphylococcus aureus is associated with S aureus infection. However, associations between S aureus carriage and the development of S aureus intensive care unit (ICU) pneumonia (SAIP) have not been quantified accurately, and interpretation of available data is hampered because of variations in definitions.

OBJECTIVE

To quantify associations of patient-related and contextual factors, including S aureus colonization status, with the occurrence of SAIP.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted in ICUs of 30 hospitals in 11 European countries, geographically spread across 4 regions. Among patients with an anticipated length of stay 48 hours or longer who were undergoing mechanical ventilation at ICU admission, S aureus colonization was ascertained in the nose and lower respiratory tract. From this group, S aureus-colonized and noncolonized patients were enrolled into the study cohort in a 1:1 ratio. Data analysis was performed from May to November 2019.

MAIN OUTCOMES AND MEASURES

SAIP was defined as any pneumonia during the ICU stay developing 48 hours or more after ICU admission with S aureus isolated from lower respiratory tract specimens or blood samples. The incidence of SAIP was derived in the study cohort and estimated on the weighted incidence calculation for the originating overarching population, while taking competing events into account. Weighted risk factor analysis was performed using Cox multivariable regression.

RESULTS

The study cohort consisted of 1933 patients (mean [SD] age, 62.0 [16.0] years); 1252 patients (64.8%) were men, and 950 patients (49.1%) were S aureus carriers at ICU admission. In all, 304 patients (15.7%) developed ICU-acquired pneumonia, of whom 131 patients (6.8%) had SAIP. Weighted SAIP incidences were 11.7 events per 1000 patient-days in the ICU for S aureus-colonized patients and 2.9 events per 1000 patient-days in the ICU for noncolonized patients (overall incidence, 4.9 events per 1000 patient-days in the ICU). The only factor independently associated with SAIP was S aureus colonization status at ICU admission (cause-specific hazard ratio, 3.6; 95% CI, 2.2-6.0; P < .001). There were marked regional differences in SAIP incidence and cause-specific hazard ratios for colonization status.

CONCLUSIONS AND RELEVANCE

SAIP incidence was 4.9 events per 1000 ICU patient-days for patients undergoing mechanical ventilation at ICU admission (or shortly thereafter). The daily risk of SAIP was 3.6 times higher in patients colonized with S aureus at ICU admission compared with noncolonized patients.

Childhood pneumonia in low-and-middle-income countries: An update

OBJECTIVES

To review epidemiology, aetiology and management of childhood pneumonia in low-and-middle-income countries.

DESIGN

Review of published English literature between 2013 and 2019.

RESULTS

Pneumonia remains a major cause of morbidity and mortality. Risk factors include young age, malnutrition, immunosuppression, tobacco smoke or air pollution exposure. Better methods for specimen collection and molecular diagnostics have improved microbiological diagnosis, indicating that pneumonia results from several organisms interacting. Induced sputum increases microbiologic yield for Bordetella pertussis or Mycobacterium tuberculosis, which has been associated with pneumonia in high TB prevalence areas. The proportion of cases due to Streptococcus pneumoniae and Haemophilus influenzae b has declined with new conjugate vaccines; Staphylococcus aureus and H. influenzae non-type b are the commonest bacterial pathogens; viruses are the most common pathogens. Effective interventions comprise antibiotics, oxygen and non-invasive ventilation. New vaccines have reduced severity and incidence of disease, but disparities exist in uptake.

CONCLUSION

Morbidity and mortality from childhood pneumonia has decreased but a considerable preventable burden remains. Widespread implementation of available, effective interventions and development of novel strategies are needed.

Prevalence of Staphylococcus aureus and Use of Antistaphylococcal Therapy in Children Hospitalized with Pneumonia

Within a cohort of >2,000 children hospitalized with community-acquired pneumonia, staphylococcal pneumonia was rare (1%) but associated with adverse in-hospital outcomes. Despite this low prevalence, use of antistaphylococcal antibiotics was common (24%). Efforts are needed to minimize overuse of antistaphylococcal antibiotics while also ensuring adequate treatment for pathogen-specific diseases.

Methicillin-Resistant Staphylococcus aureus Pneumonia in Critically Ill Trauma and Burn Patients: A Retrospective Cohort Study

BACKGROUND

The timing and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in trauma patients are not well characterized. This information is critical for the selection of appropriate empiric antibiotics. The objective of this study was to determine the incidence of MRSA pneumonia in early-onset and late-onset pneumonia and to identify risk factors for MRSA in the trauma-burn intensive care unit (ICU).

PATIENTS AND METHODS

We conducted a retrospective cohort study from January 2012 to March 2015 of patients in the trauma and burn ICU with clinical and microbiologic evidence of pneumonia. Demographics, injury type and severity, co-morbidities, antimicrobial agents, and MRSA nasal colonization at ICU admission were extracted from the medical record. A multi-variable exact logistic regression was performed to assess predictors of MRSA pneumonia.

RESULTS

Eighty patients with 88 episodes of pneumonia were included in the cohort. Ten patients had MRSA pneumonia, an overall incidence of 11.4% of pneumonia episodes with a median onset of seven days. The proportion of MRSA pneumonia episodes was not significantly different in early-onset (<5 days) or late-onset pneumonia, and there were no statistically significant risk factors for developing MRSA pneumonia. The majority of patients with MRSA had at least one known risk factor including homelessness, substance abuse, and receipt of broad-spectrum antibiotic agents.

CONCLUSIONS

The 11.4% overall incidence of MRSA pneumonia in this trauma-burn cohort was similar to what has been reported in other trauma populations, although MRSA was equally likely to be identified in early- and late-onset pneumonia. Our results suggest that risk factors other than duration of hospitalization may be important considerations in the decision to initiate MRSA-active empiric therapy for pneumonia in the trauma-burn ICU.

Antimicrobial susceptibility patterns of community- and hospital-acquired methicillin-resistant Staphylococcus aureus from United States Hospitals: results from the AWARE Ceftaroline Surveillance Program (2012-2014)

Among 8437 methicillin-resistant Staphylococcus aureus (MRSA) isolates collected from 143 medical centers in the United States (2012-2014), 7116 and 1321 were reported as community-acquired (CA) and hospital-acquired (HA) MRSA, respectively. CA-/HA-MRSA were most often isolated from patients with skin and skin structure infections (SSSI; 68.4/26.9%), pneumonia (13.7/49.0%) and bacteremia (10.0/17.7%). Overall, susceptibility rates were generally lower among HA-MRSA compared to CA-MRSA strains, especially for clindamycin (44.6 vs. 66.1%) and levofloxacin (21.4 vs. 35.5%). Also, susceptibility rates were lower for these two compounds among isolates from pneumonia compared to SSSI and bacteremia. Ceftaroline was broadly active against 98.0% of CA-MRSA and 94.3% of HA-MRSA (MIC50/90, 1μg/mL for both; no resistant isolate) overall, with little variation among infection type subsets.

Methicillin-sensitive Staphylococcus aureus CC398 in intensive care unit, France

During testing for Staphylococcus aureus in an intensive care unit in France in 2011, we found that methicillin-sensitive S. aureus clonal complex 398 was the most frequent clone (29/125, 23.2%). It was isolated from patients (5/89, 5.6%), health care workers (2/63, 3.2%), and environmental sites (15/864,1.7%). Results indicate emergence of this clone in a hospital setting.

Bacteriology of aspiration pneumonia in patients with acute coma

Loss of protective airway reflexes in patients with acute coma puts these patients at risk of aspiration pneumonia complicating the course of the primary disease. Available data vary considerably with regard to bacteriology, role of anaerobic bacteria, and antibiotic treatment. Our objective was to research the bacteriology of aspiration pneumonia in acute coma patients who were not pre-treated with antibiotics or hospitalized within 30 days prior to the event. We prospectively analyzed 127 patient records from adult patients admitted, intubated and ventilated to a tertiary medical intensive care unit with acute coma. Bacteriology and antibiotic resistance testing from tracheal aspirate sampled within 24 h after admission, blood cultures, ICU scores (APACHE II, SOFA), hematology, and clinical chemistry were assessed. Patients were followed up until death or hospital discharge. The majority of patients with acute coma suffered from acute cardiovascular disorders, predominantly myocardial infarction, followed by poisonings, and coma of unknown cause. In a majority of our patients, microaspiration resulted in overt infection. Most frequently S. aureus, H. influenzae, and S. pneumoniae were isolated. Anaerobic bacteria (Bacteroides spec., Fusobacteria, Prevotella spec.) were isolated from tracheal aspirate in a minority of patients, and predominantly as part of a mixed infection. Antibiotic monotherapy with a 2nd generation cephalosporin, or a 3rd generation gyrase inhibitor, was most effective in our patients regardless of the presence of anaerobic bacteria.

A retrospective case series of 44 patients with community-acquired Staphylococcus aureus pneumonia

AIM

Staphylococcus aureus (S. aureus) community-acquired pneumonia (CAP) is a potentially devastating and life-threatening infection. Early detection and appropriate treatment is important to prevent morbidity and death. The aim of this case series was to investigate the patient demographics, clinical features, antibiotic treatment and complications of cases of community-acquired S. aureus pneumonia occurring in the Wellington region.

METHOD

The case records of patients with radiographically confirmed community-acquired pneumonia and laboratory evidence to support S. aureus as the causative organism admitted to Wellington Regional Hospital over a 5-year period (2007-2012) were retrospectively reviewed.

RESULTS

A total of 48 presentations in 44 patients met the inclusion criteria. The majority of patients (63.6%) had underlying comorbidities. Although the mean CURB65 score was only one and fever was uncommon, 30% of patients were admitted to ICU and 16% died in hospital. Significant infective complications occurred in 48% with new lung cavitation in 20%.

CONCLUSION

This series of patients with staphylococcal pneumonia confirms the significant morbidity and mortality of the infection. A low CURB65 score and lack of objective fever should not detract from the possibility of S. aureus. The presence of bacteraemia in patients with S. aureus pneumonia needs to be regarded as a potentially deleterious finding that may necessitate a change in treatment.

Epidemiology and outcome of pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) in Canadian hospitals

Background

MRSA remains a leading cause of hospital-acquired (HAP) and healthcare-associated pneumonia (HCAP). We describe the epidemiology and outcome of MRSA pneumonia in Canadian hospitals, and identify factors contributing to mortality.

Methods

Prospective surveillance for MRSA pneumonia in adults was done for one year (2011) in 11 Canadian hospitals. Standard criteria for MRSA HAP, HCAP, ventilator-associated pneumonia (VAP), and community-acquired pneumonia (CAP) were used to identify cases. MRSA isolates underwent antimicrobial susceptibility testing, and were characterized by pulsed-field gel electrophoresis (PFGE) and Panton-Valentine leukocidin (PVL) gene detection. The primary outcome was all-cause mortality at 30 days. A multivariable analysis was done to examine the association between various host and microbial factors and mortality.

Results

A total of 161 patients with MRSA pneumonia were identified: 90 (56%) with HAP, 26 (16%) HCAP, and 45 (28%) CAP; 23 (14%) patients had VAP. The mean (± SD) incidence of MRSA HAP was 0.32 (± 0.26) per 10,000 patient-days, and of MRSA VAP was 0.30 (± 0.5) per 1,000 ventilator-days. The 30-day all-cause mortality was 28.0%. In multivariable analysis, variables associated with mortality were the presence of multiorgan failure (OR 8.1; 95% CI 2.5-26.0), and infection with an isolate with reduced susceptibility to vancomycin (OR 2.5, 95% CI 1.0-6.3).

Conclusions

MRSA pneumonia is associated with significant mortality. Severity of disease at presentation, and infection caused by an isolate with elevated MIC to vancomcyin are associated with increased mortality. Additional studies are required to better understand the impact of host and microbial variables on outcome.

Risk factors for methicillin-resistant Staphylococcus aureus in patients with community-onset and hospital-onset pneumonia

OBJECTIVES

The risk factors for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia have not been fully characterized and are likely to be different depending on whether infection is acquired in the community or the hospital.

METHODS

We conducted a case-control study of 619 adults hospitalized between 2005 and 2010 with either MRSA or methicillin-sensitive S. aureus (MSSA) pneumonia. Patients with a respiratory culture within 48 h of hospitalization had community-onset pneumonia whereas patients with a culture collected after this time point had hospital-onset pneumonia.

RESULTS

Among patients with community-onset disease, the risk for MRSA was increased by tobacco use (OR 2.31, CI 1.23-4.31), chronic obstructive pulmonary disease (OR 3.76, CI 1.74-8.08), and recent antibiotic exposure (OR 4.87, CI 2.35-10.1) in multivariate analysis while patients with hospital-onset disease had an increased MRSA risk with tobacco use (OR 2.66, CI 1.38-5.14), illicit drug use (OR 3.52, CI 2.21-5.59), and recent antibiotic exposure (OR 2.04, CI 3.54-13.01). Hospitalization within the prior three months was associated with decreased risk (OR 0.64, CI 0.46-0.89) in multivariate analysis.

CONCLUSIONS

This study suggests there are common and distinct risk factors for MRSA pneumonia based on location of onset. The decreased risk for MRSA pneumonia associated with recent hospitalization is unexpected and warrants further investigation.

SUMMARY

This case-control study showed that there are common and distinct risk factors associated with MRSA pneumonia depending on whether the infection onset is in the hospital or in the community. Recent hospitalization was unexpectedly shown to be associated with decreased risk for MRSA pneumonia and warrants further investigation.

Community acquired methicillin resistant Staphylococcus aureus pneumonia: an update for the emergency and intensive care physician

Pneumonia caused by community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) among individuals without healthcare-associated (HA) risk factors was first recognized a decade ago. CA-MRSA has now been established as a pathogen responsible for rapidly progressive, frequently fatal disease manifesting as necrotizing pneumonia, severe sepsis and necrotizing fasciitis. The frequency of occurrence, risk factors, and optimal treatment of CA-MRSA pneumonia remain unclear and vary significantly across countries. CA-MRSA is resistant to β-lactam antimicrobials due to the acquisition of novel methicillin resistance genetic cassettes. Additionally many CA-MRSA strains produce Panton-Valentine leukocidin (PVL), due to which they probably exceed the virulence of hospital-acquired MRSA isolates (HA-MRSA). CA-MRSA pneumonia requires early suspicion -especially in young otherwise healthy individuals with rapidly evolving clinical picture presenting with cavitary consolidation, bilateral infiltrates, pleural effusion and hemoptysis. Prompt hospitalization and aggressive treatment with intravenous antibiotics is warranted to improve outcomes. Therapeutic approach for severe CA-MRSA infections and particularly pneumonia is generally the same as that for invasive HA-MRSA infections. New anti-MRSA agents and possible combinations are of great importance to be evaluated in the future.

Ventilator-associated pneumonia due to meticillin-resistant Staphylococcus aureus: risk factors and outcome in a large general hospital

BACKGROUND

Data about risk factors and impact on outcome of methicillin-resistant S. aureus (MRSA) in unselected patients with ventilator-associated pneumonia (VAP) are limited.

AIM

To assess predisposing factors and outcome of VAP due to MRSA in a large teaching institution.

METHODS

Prospective study carried out over four years in the three adult ICUs of our hospital. Patients with MRSA-VAP were compared with those with bacterial VAP due to other microorganisms.

FINDINGS

Overall, 474 episodes of bacterial VAP were collected. Significant differences between MRSA-VAP (111) and VAP due to other microorganisms (363) were found for median age (68 vs. 62 years), median APACHE II score (12 vs. 11), neurosurgery (5.4% vs. 13.8%), abdominal surgery (35% vs. 19%), prior treatment with any antibiotic (82.9% vs. 64.5%) and with imipenem (24% vs. 11%) at present admission before VAP, and pleural effusion (12% vs. 5%). Multivariate analysis adjusted for confounding factors showed that higher APACHE II score, prior treatment with any antibiotic and pleural effusion were independent risk factors for MRSA. As for treatment and outcome, the differences between MRSA-VAP and other VAP were inadequate empiric treatment (70% vs. 53%), median cost of antibiotics per episode (€974 vs. €726), and in-hospital mortality (60% vs. 47%). At multivariate analysis, however, MRSA was not found to be an independent risk factor for mortality.

CONCLUSION

MRSA is a common cause of VAP. Underlying conditions predispose to its high mortality.

A novel core genome-encoded superantigen contributes to lethality of community-associated MRSA necrotizing pneumonia

Bacterial superantigens (SAg) stimulate T-cell hyper-activation resulting in immune modulation and severe systemic illnesses such as Staphylococcus aureus toxic shock syndrome. However, all known S. aureus SAgs are encoded by mobile genetic elements and are made by only a proportion of strains. Here, we report the discovery of a novel SAg staphylococcal enterotoxin-like toxin X (SElX) encoded in the core genome of 95% of phylogenetically diverse S. aureus strains from human and animal infections, including the epidemic community-associated methicillin-resistant S. aureus (CA-MRSA) USA300 clone. SElX has a unique predicted structure characterized by a truncated SAg B-domain, but exhibits the characteristic biological activities of a SAg including Vβ-specific T-cell mitogenicity, pyrogenicity and endotoxin enhancement. In addition, SElX is expressed by clinical isolates in vitro, and during human, bovine, and ovine infections, consistent with a broad role in S. aureus infections of multiple host species. Phylogenetic analysis suggests that the selx gene was acquired horizontally by a progenitor of the S. aureus species, followed by allelic diversification by point mutation and assortative recombination resulting in at least 17 different alleles among the major pathogenic clones. Of note, SElX variants made by human- or ruminant-specific S. aureus clones demonstrated overlapping but distinct Vβ activation profiles for human and bovine lymphocytes, indicating functional diversification of SElX in different host species. Importantly, SElX made by CA-MRSA USA300 contributed to lethality in a rabbit model of necrotizing pneumonia revealing a novel virulence determinant of CA-MRSA disease pathogenesis. Taken together, we report the discovery and characterization of a unique core genome-encoded superantigen, providing new insights into the evolution of pathogenic S. aureus and the molecular basis for severe infections caused by the CA-MRSA USA300 epidemic clone.

Staphylococcus aureus is a global pathogen, responsible for an array of different illnesses in humans and animals. In particular, community-associated methicillin-resistant S. aureus (CA-MRSA) strains of the pandemic USA300 clone have the capacity to cause lethal human necrotizing pneumonia, but the molecular basis for the enhanced virulence remains unclear. Bacterial superantigens (SAg) stimulate T-cell hyper-activation resulting in severe systemic illnesses such as toxic shock syndrome (TSS). However, all S. aureus SAgs identified to date are encoded by mobile genetic elements found only in a proportion of clinical isolates. Here, we report the discovery of a unique core genome-encoded SAg (SElX) which was acquired by an ancestor of the S. aureus species and which has undergone genetic and functional diversification in pathogenic clones infecting humans and animals. Importantly, we report that SElX made by pandemic USA300 contributes to lethality in a rabbit model of human necrotizing pneumonia revealing a novel virulence determinant of severe CA-MRSA infection.

[MecA and pvl genes detection in Staphylococcus aureus strains isolated from lower respiratory tract infections]

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. On the other hand, methicillin-resistant S. aureus (MRSA) is one of the high-risk and potential multi-drug resistant microorganisms.

OBJECTIVES

The aim of this study was to investigate the prevalence of mecA and pvl genes in S. aureus strains isolated from lower respiratory tract infections and to assess the antibiotic resistance profile of these strains.

MATERIAL AND METHOD

The antibiotic susceptibility testing was performed by the disk diffusion method according to CLSI recommendations in 32 consecutive non-repeated S. aureus strains isolated from sputum specimens and endotracheal aspirates of hospitalized patients over the period from January 2005 to December 2009. Only 20 strains (2008-2009) were tested for the presence of mecA and pvl genes by real-time PCR and detection with specific fluorescence probes.

RESULTS

Of the 32 S. aureus isolates, 68.7% were MRSA. MRSA strains showed higher resistance rates to gentamicin, tetracycline, rifampicin, fluoroquinolones comparing to the methicillin susceptible ones. Only one strain produced pvl; it was isolated from a 7 year old child with lethal sepsis with pulmonary and meningeal secondary localisations.

CONCLUSIONS

Glicopeptides and linezolid are therapeutic options indicated in the treatment of staphylococcal pneumonia produced either by MRSA strains or pvl positive S. aureus strains.

[Necrotizing pneumonia by community-acquired, methicillin-resistant Staphylococcus aureus in Colombia]

The emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) as a cause of severe infections has been described in the recent years. In 2006, the first report of skin and soft tissue infection by CA-MRSA was published in Colombia. Herein, two additional cases of CA-MRSA are reported with a clinical course characterized by rapid progression, prolonged stay in the intensive care unit and complication of pneumonia with the onset of empyema. Both adult patients developed acute renal failure, and were treated with linezolide; the subsequent clinical response showed adequate treatment response. Molecular characterization of the isolates indicated the presence of the mecA gene carrying the cassette SCCmec type IV and the production of the toxin panton-valentine leukocidin.

[Risk factors associated with the presence of pneumonia in patients with brain injury]

INTRODUCTION

Pneumonia in patients with head trauma occurs commonly; however, few data are available to evaluate the effects of the infection on the prognosis.

OBJECTIVE

The incidence and microbiological findings were described, and the associated risk factors were established with the appearance of pneumonia in patients with severe brain trauma.

MATERIALS AND METHODS

A prospective cohort study was conducted that included 39 patients with severe brain trauma and who required mechanical ventilation; initially, none had pneumonia. These patients were observed during a 24-month period in an attempt to discern the principal risk factors associated with the onset of pneumonia.

RESULTS

Pneumonia occurred in 31 (80%) of the 39 patients, and 28 of these presented early pneumonia. The most frequent germ in patients with pneumonia was Staphylococcus aureus with a percentage of the 42.4%. In the multivariate analysis, the single statistically significant risk factor was the presence of hypotension and vasopressor support with a RR = 27.9 (95% CI = 1.0-749.9, p < 0.05). No significant differences in the days of mechanical ventilation or mortality in both groups. The major mortality-associated risk factor in patients with pneumonia was a low Glasgow score at admittance with an OR = 2.19 (95% CI 1.03 - 4.65), p < 0.05.

CONCLUSIONS

The incidence of pneumonia in patients with severe brain trauma is high; however, its appearance does not affect the prognosis. The single significant risk factor was the presence of hypotension and vasopressor support.

Community-acquired staphylococcal pneumonia

OBJECTIVE

Staphylococcal pneumonia typically presents high rates of morbidity and mortality. It typically occurs in cases of influenza (airborne transmission) or during episodes of bacteremia (blood-borne transmission).

METHODS

A retrospective and descriptive study was conducted in patients admitted to our hospital between January of 1992 and December of 2003. All of he patients included had been diagnosed with community-acquired pneumonia caused by Staphylococcus aureus. All were older than 14 years of age, and none were intravenous drug users.

RESULTS

Community-acquired pneumonia was identified in 332 cases, of which 24 (7.3%) were identified as cases of staphylococcal pneumonia. Age ranged from 14 to 89 years. Fifteen patients were male, and nine were female. Twelve patients met the criteria for severe pneumonia. Chest X-rays showed unilateral consolidation in 14 cases, bilateral consolidation in 10, pleural effusion in 15, rapid radiological progression of pulmonary lesions in 14, cavitation in 6 and pneumothorax in 1. Most of the patients presented comorbidities, of which diabetes mellitus was the most common. Twelve patients presented complications such as empyema and septic shock. Four patients died, translating to a mortality rate of 16.6% in our sample.

CONCLUSIONS

The clinical presentation of pneumonia caused by S. aureus is similar to that of pneumonia caused by other etiological agents. Radiological findings, epidemiological data and risk factors provide important clues to the diagnosis. These factors are important for clinical suspicion, since S. aureus is not typically addressed in empirical treatment.

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.

[Community-acquired methicillin-resistant Staphylococcus aureus infections in a hospital for acute diseases]

Community-acquired methicillin-resistant Staphylococcus aureus infections in a hospital for acute diseases. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens associated with nosocomial infections. However, most recently, MRSA has arisen as an emerging community pathogen, causing serious infections, mainly among young patients. We herein describe 33 cases of infections caused by community-acquired MRSA (C-MRSA), diagnosed between May 2005 and June 2006, at "Eva Perón" Hospital. The isolations were retrospectively studied. Methicillin resistance was confirmed by means of the detection of the mecA gene, and the genes for two virulence factors (Panton-Valentine Leucocidin -PVL- and gamma-haemolysin) as well as the cassette mec type were screened by PCR. All the patients were previously healthy. Four patients under 12, presented bacteremia, one had serious pneumonia, and the three remaining patients had osteoarticular infections; all the patients over 12, had skin and soft tissue infections without systemic damage. The C-MRSA strains harboured cassette mec type IV, and the PVL and gamma-haemolysin genes. They were methicillin-resistant, with no other associated resistances. It is important to consider the presence of these community- acquired strains in order to develop strategies for their correct treatment.

[Comparison of nursing home-acquired pneumonia with community-acquired elderly pneumonia]

To clarify whether the environment of a nursing home affects the clinical features of patients with pneumonia, we compared the characteristics of 103 patients (nursing home group) who suffered from pneumonia at a nursing home with 153 elderly patients with the same background (community group) who lived in their own home. Although there were no significant differences in CRP, WBC, and body temperature at admission and duration of hospitalization, the degree of independency of the nursing home group was significantly lower than the community group. As the degree of independency became worse, the length of hospitalization extended and mortality increased. Bacteriological findings of sputum culture showed that methicillin-resistant Staphylococcus aureus (MRSA) was cultured in 20 cases (19%) of the nursing home group and 18 cases (13%) of the community group. In isolated analysis of total care cases, MRSA positive rates were similar in the nursing home group (17/58; 29%) and the community group (8/30; 27%). Only 1 case with penicillin-susceptible Streptococcus pneumoniae (PSSP) was found in the nursing home group, however 7 species of PSSP were cultured in the community group, including 5 self-help cases. Pseudomonas aeruginosa was cultured in 8 patients of each group, and most of them were total care cases. We concluded that the difference in frequency and species of bacteria depended on the condition of patients, rather than the environment, and differences in conditions might lead to differences in clinical features.

[Detection of group B streptococcus in the cases died of neonatal pneumonia]

OBJECTIVE

From the 1970s, group B streptococci (GBS) have been widely recognized as an important pathogen in neonatal infectious disease, and it emerged as the leading cause of neonatal morbidity and mortality in the Western world. However, there are few data on the prevalence of neonatal GBS infections in China. The aim of this retrospective study was to estimate whether GBS is an important pathogen in severe neonatal pneumonia, and to develop a method for detection of GBS infections in fatal neonatal pneumonia.

METHODS

A total of 234 neonatal cases (0 - 28 days) died in Beijing Children's Hospital from 1953 to 2004 were enrolled in this study. They were divided into two groups. Two hundred cases diagnosed as neonatal pneumonia were assigned to study group and the remaining 34 cases died of neonatal hemolysis or surgical operation without any confirmed infectious diseases were designated as control group. Formalin-fixed, paraffin-embedded lung tissues were used as source for total genomic DNA extraction. PCR and Southern blot analyses were applied to detect GBS specific cfb gene target sequence. And the clinical data of these cases were reviewed as well.

RESULTS

In the study group, 52 cases were detected positive for GBS DNA by PCR (26%), 130 cases were positive by Southern blot (65%). In the control group, 1 case was detected positive GBS DNA by PCR (3%), and 6 cases were positive by Southern blot (18%). The positive rate was significantly lower in the control group than that in the study group (PCR, chi(2) = 8.82, P < 0.01; Southern blot, chi(2) = 26.77, P < 0.01). The positive rate in the neonates younger than 7 days (early-onset) was significantly higher than that in neonates older than 7 days (late-onset) (PCR: 37% vs. 13%, chi(2) = 15.537, P < 0.01; Southern blot: 72% vs. 52%, chi(2) = 4.37, P < 0.05). In the positive early-onset cases, 39% of whom were born prematurely (29/74). Out of the 200 cases, 75 had complete clinical data. Neither blood nor lung culture for GBS was performed in any of these cases. But risk factors were identified for 35 cases, such as premature delivery, low birth weight, premature rupture of the membrane and abnormal amniotic fluid. GBS was positive in all these cases. Severe apnea appeared to be a common symptom and was present in most of the early-onset GBS-positive cases, while cough and wheezing were found in most of the late-onset GBS-positive cases. In the control group, one PCR positive case was suffered from malignant teratoma. The other 5 positive cases confirmed by Southern blot were diagnosed as kernicterus, hepatoma, aproctia complicating with cysti-urethral fistula, neonatal physio logical bleeding and aproctia complicated with archo-perineal fistula.

CONCLUSION

Group B Streptococcus is an important pathogen in fatal neonatal pneumonia, especially in early-onset cases. southern blot may be a sensitive method to detect GBS infection in archival tissues. In the clinical work, more attention should be paid to the neonates with GBS risk factors. And GBS detection and prevention in neonates should be put into clinical practice.

Methicillin-resistant Staphylococcus aureus: a new community-acquired pathogen?

PURPOSE OF REVIEW

The main goal of this review is to describe the emergence of methicillin-resistant Staphylococcus aureus (MRSA) as a community pathogen.

RECENT FINDINGS

Community-acquired MRSA has emerged as an important infection in the community setting. It has primarily been associated with skin and soft-tissue infections, but can also cause severe pulmonary infections, including pneumonia and empyema. Community-acquired MRSA is typically more susceptible to a wider class of antibiotics than healthcare-associated MRSA. Community-acquired MRSA is also more virulent compared with healthcare-associated MRSA isolates. Community-acquired MRSA usually contains the gene encoding Panton-Valentive leukocidin, which is a toxin that creates lytic pores in the cell membranes of neutrophils and induces the release of neutrophil chemotactic factors that promote inflammation and tissue destruction. The optimal antibiotic treatment for Panton-Valentive leukocidin-positive community-acquired MRSA is unknown; however, antibiotics with activity against MRSA and the ability to inhibit toxin production may be optimal (linezolid or clindamycin for susceptible isolates).

SUMMARY

Clinicians should be aware of the emergence of community-acquired MRSA as an important cause of serious infections arising in the community setting. Appropriate antibiotic therapy should be initiated as soon as infection with this pathogen is suspected.

Suspected ventilator-associated pneumonia in cardiac patients admitted to the coronary care unit

OBJECTIVE

To determine the incidence, risk factors, associated pathogens, and outcome of ventilator-associated pneumonia (VAP) in patients admitted to a coronary care unit (CCU).

PATIENTS AND METHODS

This retrospective cohort study was performed in the CCU of a single tertiary medical center. Patients who were admitted to the CCU between March 23, 2002, and May 25, 2003, and who required invasive mechanical ventilation for more than 48 hours were included.

RESULTS

Of the 92 patients who met the study criteria, 17 (18.5%; 95% confidence interval, 11.9%-27.6%) developed VAP. The incidence of VAP was 36.3 (95% confidence interval, 21.1-58.1) per 1000 days of mechanical ventilation. There were no statistically significant differences in demographics, presence of chronic obstructive pulmonary disease, or use of continuous intravenous sedatives or neuromuscular blockers between patients with and without VAP. The most commonly isolated organisms were methicillin-sensitive Staphylococcus aureus, Sphingomonas paucimobilis, and Stenotrophomonas maltophilia. The median length of stay in the CCU for patients with VAP was 10 days compared to 6 days for patients without VAP (P < .01). Eight (47%) of the 17 patients with VAP died compared to 29 (39%) of 75 patients without VAP (P = .52).

CONCLUSIONS

The incidence of VAP in the CCU is similar to or higher than that reported in other intensive care units. The development of VAP in CCU patients is associated with a prolonged CCU stay but not with an increased hospital mortality.

Antibiotic management of ventilator-associated pneumonia due to antibiotic-resistant gram-positive bacterial infection

Gram-positive cocci, in particular Staphylococcus aureus, account for as much as one-third of all cases of hospital-acquired pneumonia, and treatment has become increasingly complex as the proportion of resistant isolates has increased. Methicillin-resistant S. aureus is of particular concern because this pathogen is now associated with hospital-acquired, ventilator-associated, community-acquired, and healthcare-associated pneumonia. Antibiotic therapy for ventilator-associated pneumonia is challenging because it can be caused by multiple pathogens, which can be resistant to multiple drugs. This article reviews the epidemiology of ventilator-associated pneumonia and describes options for antibiotic treatment. Particular attention is paid to pneumonia due to methicillin-resistant S. aureus. Studies suggest that vancomycin, the traditional treatment for ventilator-associated pneumonia, may not be the best option for this type of pneumonia and that other antibiotics, such as linezolid and clindamycin, might be better choices. New antibiotics with activity against methicillin-resistant S. aureus are under investigation and may soon become available for clinical use. Studies are needed to define the optimal choice of antibiotic for pneumonias caused by this organism, and these choices will need to be balanced with the need to minimize the emergence of resistance.

Neumonía nosocomial causada por Staphylococcus aureus resistente a meticilina

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common cause of hospital acquired pneumonia (HAP) and the second most frequently isolated pathogen from patients who die from HAP. High-risk units for MRSA colonization such as intensive care (ICU's) are the most affected. Multiple risk factors for transmission of MRSA have been identified, including colonization pressure and severity of illness at ICU admission. On the other hand, the most important predisposing factor for MRSA infection is prolonged mechanical ventilation and/or previous antibiotic therapy. Controlling the spread of MRSA remains a major challenge for hospitals. Screening programs, together with contact precautions for cases with MRSA and judicious antimicrobial use are major factors for a successful control. Early appropriate initial therapy is of crucial importance and improves outcome. The standard therapy has been glycopeptides but, in spite of its in vitro activity, mortality in critically ill patients treated with glycopeptides has consistently been reported high, mainly due to their poor lung penetration. Linezolid shows better clinical cure and survival rates, but further studies are needed. As the treatment options for MRSA pneumonia are limited and inadequate, development of more effective drugs is mandatory.

Epidemiology, treatment, and outcomes of nosocomial bacteremic Staphylococcus aureus pneumonia

OBJECTIVE

To describe outcomes associated with nosocomial bacteremic Staphylococcus aureus pneumonia (NBSAP) and to determine whether delay in adequate antimicrobial treatment is a risk factor for negative clinical and microbiological outcomes.

DESIGN

Retrospective cohort analysis.

SETTING

This study was conducted at Detroit Receiving Hospital and University Health Center, which is a 279-bed, level 1 trauma center in Detroit, MI.

PATIENTS

All episodes of NBSAP identified from January 1, 1999, to April 30, 2004.

RESULTS

Of 206 patients identified over a 5-year period with positive blood and respiratory cultures for S aureus, 60 patients met strict clinical, radiographic, and microbiological criteria for NBSAP. The overall mean (+/- SD) characteristics include the following: age, 55.5 +/- 15.0 years; acute physiology and chronic health evaluation II score, 20 (range, 3 to 41); ICU at onset, 93.3%; mechanical ventilation, 83.3%; length of stay (LOS) prior to NBSAP, 9 days (range, 2 to 81 days); methicillin-resistant S aureus (MRSA) rate, 70%; and all-cause hospital and infection-related mortality (IRM), 55.5% and 40.0%, respectively. Overall, S aureus pneumonia developed late in the patient's hospital stay in ICU patients previously receiving mechanical ventilation and was associated with high crude mortality and IRM rates. No significant difference existed with respect to mortality or infection-related LOS between patients who had received early appropriate antibiotic therapy vs those who had received delayed appropriate antibiotic therapy at the onset of pneumonia or in patients with methicillin-sensitive S aureus pneumonia vs those with MRSA pneumonia.

CONCLUSION

IRM from NBSAP is high, and standard therapies evaluated at the time of this study resulted in poor clinical outcomes. Delayed therapy was not found to be a predictor of adverse outcomes; however, this lack of ability to detect a difference may be a product of small sample size. These findings suggest that newer agents with enhanced clinical activity in NBSAP are needed and that these should be evaluated in a real-world setting, where outcomes of the most ill patients can be assessed.

[Staphylococcal pneumonia]

In January to December 2000, a total of 15 (8.8%) patients with staphylococcal community-acquired pneumonia (CAP), 13 (27.7%) patients with staphyloccocal nosocomial pneumonia (NP) that occurred at general units (GU), and 9 (50%) patients with GU that occurred under artificial ventilation (AV) at intensive care units (ICU) were followed up. Meticillin-resistant S. aureus strains were isolated in 6.7, 38.5, and 55.6% of cases, respectively. As compared with pneumococcal CAP, staphyloccocal CAP were more frequently characterized by the severe course of the disease (46.7% versus 15.4%), bilateral lesion (33.3% versus 5.1%), and the presence of complications (66.7% versus 30.8%). Staphyloccocal NP that had occurred at GU, as compared to that at ICU also showed the severe course of the disease (46.2% versus 2.9%), bilateral lesion (30.7% versus 0%), and developed complications (75% versus 25%). Staphylococcal NP developed under AV at ICU had no specific features as compared with NP of another etiology. Oxacillin and first-second-generation cephalosporins remain to be the drugs of choice when meticillin-sensitive S. aureus strains are isolated; lincomycin and erythromycin being alternative agents against these strains. Glycopeptides are the drugs of choice when meticillin-resistant S. aureus strains are isolated, its alernatives are linesolide or rifampicin. High mortality rates due to staphylococcal pneumonia are preserved. These are 7.1% in CAP, 7.7 and 66.7 in staphylococcal NP occurring at GU and under AV at ICU, respectively.

Staphylococcus aureus bacteremic pneumonia: differences between community and nosocomial acquisition

OBJECTIVE

The aim of the study was to ascertain the clinical and epidemiologic characteristics of patients with nosocomial or community-acquired Staphylococcus aureus bacteremic pneumonia.

METHODS

A prospective study of 134 cases diagnosed between January 1990 and December 1995 was performed.

RESULTS

Fifty cases involved primary bacteremic pneumonias, of which 80% were nosocomial (the majority, 72%, in intensive care unit patients, of whom 57% were post-surgery). Of the 84 cases of secondary pneumonia, 36 were non-intravenous drug users (78% nosocomial, of whom 43% were in the intensive care unit), and 48 cases were intravenous drug users (98% community-acquired).

CONCLUSIONS

Nosocomial S. aureus bacteremic pneumonia was especially frequent in intensive care unit patients (68.1%), and community-acquired pneumonia in intravenous drug users (72.3%). In non-intravenous drug users, clinical outcome and mortality were similar for nosocomial and community-acquired pneumonia.

Vaccine development for capsulate bacteria causing pneumonia

Pneumonia strikes the extremes of the age spectrum, causing maximal death and disability in children and the elderly. Despite its worldwide impact, there is a paucity of epidemiologic data regarding its incidence and the causative organisms. The two leading causes of bacterial pneumonia in childhood are Streptococcus pneumoniae (SP) and Haemophilus influenzae type b (Hib). SP is the major cause of pneumonia beyond the newborn period. In neonates, Group B Streptococcus (GBS) remains a major cause of sepsis and pneumonia despite recent reductions due to targeted perinatal antibiotic prophylaxis. Hib vaccine can prevent pneumonia in developing countries. SP conjugate vaccine prevents X-ray confirmed pneumonia in low incident populations, but protection appears more marginal in high incident populations. Non-vaccine SP serotypes have demonstrated increased carriage and mucosal disease, but not invasive disease following vaccination. GBS vaccines are in the early stages of clinical development as prenatal or antenatal vaccines.

[Influence of nutritional status on development of nosocomial pneumonia in case of acute decompensation of chronic obstructive pulmonary diseases]

OBJECTIVE

The aim of this retrospective study was to assess the incidence of nutritional status on the development of nosocomial pneumonia in patients with chronic obstructive pulmonary disease (COPD) suffering an acute episode of respiratory failure requiring ventilatory assistance.

PATIENTS AND METHODS

The study included 48 patients with COPD who were hospitalized in an intensive care unit for acute respiratory failure requiring ventilatory assistance. Nutritional status was assessed within 24 hours of admission to the intensive care unit. Body weight, tricipital skin fold, brachial muscle circumference, creatinuria-waist index, plasma levels of albumin, transferrin, transthyretin and retinol-binding protein, the Multitest and lymphocyte counts were recorded. The diagnosis of nosocomial pneumonia was based on recognized criteria: occurrence more than 48 hours after admission, Andrews' criteria for bacterial pneumonia and bacteriological proof.

RESULTS

Nineteen of the 48 patients developed nosocomial pneumonia. The nutritional parameters at admission to intensive care were not significantly different between patients who developed nosocomial pneumonia and those who remained free of lung infection. The duration of ventilatory assistance and total stay in the intensive care unit were significantly longer in patients who developed nosocomial pneumonia.

CONCLUSION

This study showed that in patients with COPD who undergo ventilatory assistance for acute decompensation, the development of nosocomial pneumonia was not correlated with nutritional status admission.

Clarithromycin in the management of community-acquired pneumonia

OBJECTIVE

To review the epidemiology and diagnosis of community-acquired pneumonia (CAP) and examine factors that influence the choice of empiric antimicrobial therapy.

BACKGROUND

CAP remains a common disease with substantial associated morbidity and mortality. Outpatient management of patients with CAP has become increasingly complex because of the availability of newer antimicrobial agents, evolving patterns of resistance, and the increasing recognition of atypical pathogens. Although Streptococcus pneumoniae remains a commonly encountered pathogen, the development and increasing prevalence of antibiotic resistance has become an area of concern, especially in outpatients. The newer macrolide antimicrobial drugs-clarithromycin and azithromycin-are effective against commonly encountered pathogens, are well tolerated, and have an established tolerability profile, although the low serum levels achieved by azithromycin hinder its use in patients with suspected bacteremia.

METHODS

A MEDLINE search was performed of English-language articles published from 1990 to 2000 on the treatment of CAP. This article reviews the treatment of CAP, with emphasis on the use of clarithromycin.

CONCLUSION

Although laboratory surveillance studies have reported macrolide-resistant S. pneumoniae, recent evidence defining the mechanism of this resistance, coupled with the pharmacokinetic properties of the macrolide agents, suggests that the actual rate of clinical macrolide resistance is low.

Primary staphylococcal pneumonia in young children: a review of 100 cases

Staphylococcus aureus (S. aureus) is responsible for a small proportion of acute respiratory infections in children. Nevertheless a high index of suspicion is required because of the potential for rapid progression, the need for antibiotics different to those routinely administered in the treatment of pneumonia, and the high incidence of complications. There are few data from developing countries. The objective of this retrospective review was to document the natural history of primary staphylococcal pneumonia at Red Cross Childrens' Hospital in Cape Town over a 7-year period (1989-1995). Staphylococcal pneumonia was defined as acute pneumonia with microbiological evidence of S. aureus or with characteristic radiological features. One hundred patients were identified. The median age was 5 months, 78 patients being below one year of age. Cough and fever were present in almost all patients at the time of presentation. Tachypnoea, recession, dullness, and crepitations were commonly elicited signs. Initial chest radiographs revealed empyema, pleural effusion, or pyopneumothorax in 67 patients. A further 26 patients developed such changes on subsequent chest radiographs. Pneumatocoeles were identified in 37 patients--most of these were only noted on radiographs taken some days after admission. Microbiological confirmation was obtained in 92 cases. S. aureus was isolated in 23/98 blood cultures, 62/67 pleural aspirates, and from tracheal aspirates in 16 cases. Intercostal drains were inserted in 67 cases and 20 children underwent thoracotomy. The case fatality rate was 7 per cent. This study shows that primary staphylococcal pneumonia is chiefly a disease of infants. Symptoms and signs were similar as for other forms of acute pneumonia, although in the majority of cases chest radiographs taken at the time of admission suggested the diagnosis. Treatment with antibiotics and drainage of empyema resulted in a good outcome in the majority of cases.

[Pleuropulmonary staphylococcal infection in infants, in a hospital environment in Ouagadougou (Burkina Faso)]

We observed 36 cases of pleuropulmonary staphylococcal infection (PPS) in infants aged 0 to 30 months, during a prospective study carried out between April 1st 1995 and March 31 1996 at the Pediatrics Department of Ouagadougou University Hospital. PPS accounted for 0.5% of all hospital admissions and 11.6% of all acute basal respiratory infections in children aged less than 30 months. Slightly more boys than girls were affected, with a sex ratio of 1.2. We identified the classic triad of symptoms: cough-fever-polypnea, associated with abdominal ballooning and a change in general condition. On X rays, the typical images showing parenchymatous bubbles were the second most frequent observation (27.8%) after parenchymatous opacities (69.5%). The most frequently used antibiotics were oxacillin (Bristopen), gentamycin (Gentallin) and cefuroxime-axetil (Zinnat). The prognosis of PPS is poor, with a high mortality rate (27.8%) and a risk of pleural recurrence. Being very young, late hospitalization, malnutrition and leukopenia were identified as factors indicating a poor prognosis. Recygling of health care personnel for the management of acute respiratory infections, a decrease in malnutrition and an improvement in vaccination cover are essential if the mortality and morbidity of acute respiratory infections, and PPS in particular, are to be reduced.

[Non-tuberculous bacterial pleuropneumopathies in children in Abidjan]

We carried out a retrospective study to investigate epidemiological and clinical aspects of patient management in a hospital environment. We studied 90 cases of non-tuberculous bacterial pleuropneumopathies in children, observed over a 5-year period, from January 1 1991 to December 31 1995, at the Pediatric Medical Unit of Yopougon University Hospital. Diagnosis was based on the association of an infectious syndrome with respiratory and digestive disorders, and was confirmed by X ray. Bacteria were isolated from pleural pus and identified in fifty-one cases. Non-tuberculous bacterial pleuropneumopathies accounted for 5.22% of all pneumopathies in children, and the sex ratio for the patients affected was 1.9. Protein and energy malnutrition, anemia, being very young and climatic factors (harmattan and rainy seasons) were identified as major risk factors. The three main bacteria identified were Staphylococcus aureus (21 cases), Streptococcus pneumoniae (19 cases) and Haemophilus influenzae (6 cases). In this series of patients, 20% of the Staphylococcus aureus strains isolated were methicillin-resistant. Patients were generally treated with a combination of penicillin A and M and aminoside, with or without a pleural drain. The outcome was favorable in 77.8% of cases, with no severe sequelae detected by X ray. Six of the children died. Bacterial pneumopathies are still common in Sub-Saharan Africa and the patient being very young is indicative of a poor prognosis.

Epidemiology of ventilator-acquired pneumonia based on protected bronchoscopic sampling

We performed a prospective observational cohort study of the epidemiology and etiology of nosocomial pneumonia in 358 medical ICU patients in two university-affiliated hospitals. Protected bronchoscopic techniques (protected specimen brush and bronchoalveolar lavage) were used for diagnosis to minimize misclassification. Risk factors for ventilator-associated pneumonia were identified using multiple logistic regression analysis. Twenty-eight cases of pneumonia occurred in 358 patients for a cumulative incidence of 7.8% and incidence rates of 12.5 cases per 1, 000 patient days and 20.5 cases per 1,000 ventilator days. Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Hemophilus species made up 65% of isolates from the lower respiratory tract, whereas only 12.5% of isolates were enteric gram-negative bacilli. Daily surveillance cultures of the nares, oropharynx, trachea, and stomach demonstrated that tracheal colonization preceded ventilator-associated pneumonia in 93.5%, whereas gastric colonization preceded tracheal colonization for only four of 31 (13%) eventual pathogens. By multiple logistic regression, independent risk factors for ventilator- associated pneumonia were admission serum albumin <= 2.2 g/dl (odds ratio [OR] 5.9; 95% confidence interval [CI] 2.0-17.6; p = 0.0013), maximum positive end-expiratory pressure >= 7.5 cm H2O (OR, 4.6; 95% CI, 1.4 to 15.1; p = 0.012), absence of antibiotic therapy (OR, 6.7; 95% CI, 1.8 to 25.3; p = 0.0054), colonization of the upper respiratory tract by respiratory gram-negative bacilli (OR, 3.4; 95% CI, 1.1 to 10.1; p = 0.028), pack-years of smoking (OR, 2.3 for 50 pack-years; 95% CI, 1. 2 to 4.2; p = 0.012), and duration of mechanical ventilation (OR, 3. 4 for 14 d; 95% CI, 1.5 to 7.8; p = 0.0044). Several of these risk factors for ventilator-associated pneumonia appear amenable to intervention.

[Staphylococcal pneumonia--analysis of material from patients treated at the Hospital for Lung Diseases in the years 1981-1994]

Retrospective analysis of staphylococcal pneumonia was made in 182 patients, aged 18-88 years /61% more than 60 years old/ treated in hospital in years 1981-1994. Majority of these patients had various concomitant diseases, mostly chronic bronchitis and lung cancer. Strains of Staphylococcus aureus were sensitive mainly to amoxycillin--clavulanic acid, roxitromycin, amikacin, netilmicin, clindamycin, cefamandol, chloramphenicol, rifampicin and resistant mostly to penicillin /90% of strains/, ampicillin, tetracyclines. In many cases initial antibacterial treatment was inadequate in relation to sensitivity pattern of staphylococci--hence many changes of antibiotics were observed in the course of the therapy. Newer antistaphylococcal drugs were applied only in the last years of the study. Despite these therapeutical drawback outcome of staphylococcal pneumonia was good in 85% of patients; 14% of patients died /mainly as a consequence of comorbidities/. Successful therapy of staphylococcal pneumonia requires early recognition of possibility of infection due to Staphylococcus aureus and adjustment of drugs to probable or actual sensitivity of these pathogens.

Clinical and epidemiological findings in mechanically-ventilated patients with methicillin-resistant Staphylococcus aureus pneumonia

Over the 5-year period from 1990 to 1994, a prospective cohort study was conducted to define the clinical and epidemiological characteristics of ventilator-associated methicillin-resistant Staphylococcus aureus (MRSA) pneumonia acquired during a large-scale outbreak of MRSA infection. Of 2411 mechanically ventilated patients, 347 (14.4%) acquired MRSA, 220 (63.4%) had MRSA positive respiratory tract samples and 41 (18.6%) developed ventilator-associated MRSA pneumonia. The overall attack rate for ventilator-associated MRSA pneumonia was 1.56 episodes/1000 ventilator days, but annual attack rates varied according to the trend of the outbreak (range 4.9-0.2). In comparison with methicillin-sensitive Staphylococcus aureus (MSSA), which was implicated in 98 episodes of ventilator-associated pneumonia, MRSA caused exclusively late-onset ventilator-associated pneumonia, while MSSA caused both early-onset [55 of 98 (56.1%) episodes] and late-onset [43 of 98 (43.8%) episodes] ventilator-associated pneumonia. Logistic regression analysis of all patients with Staphylococcus aureus pneumonia revealed intubation for more than 3 days (odds ratio (OR),1.11; confidence interval (CI):1.03-1.18) and prior bronchoscopy (OR,5.8; CI,1.85-18.19) to be independent variables associated with MRSA pneumonia. The results indicate that MRSA ventilator-associated pneumonia is a frequent complication in intensive care patients, manifesting itself as late-onset pneumonia in patients who have been intubated for prolonged periods and/or have often undergoing previous bronchoscopy.

Pulmonary complications of HIV infection: autopsy findings

STUDY OBJECTIVES

To describe the pulmonary complications in patients with HIV infection, and the changes in the incidence of these complications over a 12-year period.

DESIGN

Retrospective review of autopsy records.

SETTING

Two university-affiliated medical centers.

PATIENTS

We studied autopsy findings from 233 patients with HIV infection who died between 1985 and 1996. Demographic data, risk factors for HIV infection, and the lengths of hospital stay were obtained. The histologic and microbiological findings of the respiratory system, and the extrapulmonary organ involvement by Kaposi's sarcoma (KS), Pneumocystis carinii, Mycobacterium tuberculosis, and Mycobacterium avium complex were reviewed.

RESULTS

Ninety-two percent of the patients were black and 75% were male. The two most common identified risk factors for HIV infection were homosexuality (34%) and injection drug use (27%). Bacterial pneumonia was the most frequent pulmonary complication (42%). The two most common causes of bacterial pneumonia were Pseudomonas aeruginosa and Staphylococcus aureus. P carinii pneumonia (PCP) was found in 24%, with extrapulmonary involvement in 13%. Pulmonary mycobacterial infections were seen in 33%, with multiple extrapulmonary involvement. The most common site affected by KS was the lung. Of all pulmonary complications, only the incidence of PCP decreased over the 12-year period.

CONCLUSIONS

Recognizing the high incidence rate of bacterial pneumonia, the high frequency of pulmonary KS and the not uncommon occurrence of extrapulmonary P carinii infection in patients with HIV helps in improving their care.

[A molecular and epidemiology study in patients with ventilator-associated pneumonia]

OBJECTIVE

To evaluate causative agents in patients with ventilator-associated (VA) pneumonia epidemiologically, then to provide useful suggestion for diagnosis and treatment of VA pneumonia.

METHOD

Prospectively, a protected specimens brush was used to obtain the secretion of lower respiratory tract of 65 patients, who had been receiving mechanical ventilation or tracheostomy for more than 72 hours. At the same time, other samples were collected from the relevant places, including pharyngeal and gastric juice of patients as well as other persons, ward's air. The secretion obtained were cultured with a quantitative method. Then all bacteria isolated were studied with the analysis of pattern of plasmids and chromosomal restriction endonuclease.

RESULT

It was showed that the route of infection of the Gram-negative bacilli in VA pneumonia (19 cases) was intrinsic, a retrograde colonization from patient's stomach, that was the pattern of clonization from stomach to pharynx, then into lower respiratory tract, and the Gram-positive staphylococcus spread mainly through the ward's air, then directly into lower respiratory tract, or extrinsic (20 cases).

CONCLUSION

The Gram-positive staphylococcus is also major disease-producing germs in VA pneumonia, and the infection routes of G+ and G- bacteria might be different.

Reducing the incidence of ventilator-related pneumonia

Ventilator-related pneumonia is costly not only in terms of treatment, equipment, and length of stay but also in terms of patient morbidity and mortality. From October 1995 through March 1996 an increase in ventilator-related pneumonia cases, of which 83% were caused by methicillin-resistant Staphylococcus aureus (MRSA), was noted at a Veterans Affairs medical center. A multidisciplinary team based on the TQI model and using TQI tools, methodology, and principles of problem solving was subsequently formed to look into ventilator-related pneumonia. The team's data collection and analysis efforts identified numerous opportunities for improvement. The primary outcome has been a decrease in the incidence of ventilator-related pneumonia that has resulted in substantial cost savings.

Bacteremic nosocomial pneumonia. A 7-year experience in one institution

STUDY OBJECT

To describe the epidemiology, microbiology, and outcome of nosocomial pneumonia with secondary bloodstream infection.

DESIGN

Prospective cohort study.

SETTING

Tertiary care Canadian teaching hospital.

PATIENTS

Inpatients.

MEASUREMENT

All inpatient blood cultures were concurrently monitored over an 89 month period. Following chart review, patients experiencing nosocomial bloodstream infection due to pneumonia were identified. A standardized definition of pneumonia was used.

RESULTS

One hundred forty-nine episodes occurred in 145 patients, 0.66/1,000 hospital admissions, 8.4% of all nosocomial bloodstream infections. No change in rate occurred in the study period. Fifty-four percent of episodes developed in one of seven ICUs. Staphylococcus aureus was the most frequently identified etiologic organism (27%). The ICU and non-ICU cases did not differ in etiology. No organism became more prevalent during the study period. Twenty percent of patients died within 1 week of first positive culture; episodes associated with Pseudomonas species had a much higher mortality rate (45%) than other infections (14%) (p = 0.002). The ICU and non-ICU infections had a similar mortality rate.

CONCLUSION

Pneumonia is an important cause of nosocomial bloodstream infection, but it is not increasing in frequency or changing in etiology in our institution. The ICUs are a major contributor to this problem but have the same case short-term mortality rate and microbial etiology as non-ICU cases. Cases associated with Pseudomonas have a much higher mortality rate.