Pathogens in the lower respiratory tract of intensive care unit patients: impact of duration of hospital care and mechanical ventilation

Identification of Streptococcus pneumoniae in hospital-acquired pneumonia in adults

Hospital-acquired pneumonia (HAP) is often more severe and life-threatening than community-acquired pneumonia (CAP). The role of Streptococcus pneumoniae in CAP is well-understood, but its role in HAP is unclear. The objective of this study was to summarize the available literature on the prevalence of S. pneumoniae in HAP episodes. We searched MEDLINE for peer-reviewed articles on the microbiology of HAP in individuals aged ≥18 years, published between 2008 and 2018. We calculated pooled estimates of the prevalence of S. pneumoniae in episodes of HAP using a random-effects, inverse-variance-weighted meta-analysis. Forty-seven of 1908 articles met the inclusion criteria. Bacterial specimen isolation techniques for microbiologically defined HAP episodes included bronchoalveolar lavage, protective specimen brush, tracheobronchial aspirate and sputum, as well as blood culture. Culture was performed in all studies; five studies also used urine antigen detection (5/47; 10.6%). S. pneumoniae was identified in 5.1% (95% confidence interval (CI): 3.8-6.6%) of microbiologically defined HAP episodes (N = 20), with 5.4% (95% CI: 4.3-6.7%, N = 29) in ventilator-associated HAP and 6.0% (95% CI: 4.1-8.8%, N = 6) in non-ventilator-associated HAP. S. pneumoniae was identified in 5.3% (95% CI: 4.5-6.3%) of HAP occurring in the intensive care unit (ICU, N = 41) and in 5.6% (95% CI: 3.3-9.5%, N = 5) outside the ICU. A higher proportion of early-onset HAP (10.3%; 95% CI: 8.3-12.8%, N = 16) identified S. pneumoniae as compared with late-onset HAP (3.3%; 95% CI: 2.5-4.4%, N = 16). In conclusion, S. pneumoniae was identified by culture in 5.1% of microbiologically defined HAP episodes. The importance of HAP as part of the disease burden caused by S. pneumoniae merits further research.

Multidrug-Resistant Infections Among Hospitalized Adults With Community-Acquired Pneumonia In An Indonesian Tertiary Referral Hospital

Objectives

To evaluate the clinical and microbiological appearance among hospitalized pneumonia patients focusing on resistance and risk factors for mortality in a referral hospital.

Patients and methods

The study was an observational retrospective study on patients with CAP from 2014 to 2016 at Dr Soetomo referral hospital of Surabaya, Indonesia. All positive cultures with antimicrobial susceptibility results from blood and respiratory specimens were included. Patients infected with drug-susceptible pathogens and MDR organisms were also assessed in terms of clinical characteristics, day-3 clinical improvement, and 14-day mortality.

Results

Of 202 isolates, 181 possessed antimicrobial susceptibility data. S. pneumoniae was the most prevalent pathogen causing CAP (18.3%). Most patients were empirically treated with ceftriaxone (n=75; 41.4%). Among beta-lactam antibiotics, the susceptibility to the third-generation cephalosporins remained relatively high, between 67.4% and 82.3%, compared with the other beta-lactams such as amoxicillin/clavulanate and ampicillin/sulbactam (a sensitivity rate of 36.5% and 47.5, respectively). For carbapenem antibiotics, imipenem and meropenem susceptibility was 69.6% and 82.3% respectively. Approximately 22% of isolates were identified as MDR that showed significant differences in clinical outcomes of 14-day mortality rates (p<0.001). Notably, patients with day-3 improvement had a lower risk of mortality (OR= 0.06; 95% CI= 0.02–0.19).

Conclusion

One-fifth of causative agents among hospitalized CAP cases were identified as MDR organisms. The pathogens of MDR and non-MDR CAP remain susceptible to the third-generation cephalosporins. Together with additional consideration of culture findings and Pneumonia Severity Index (PSI) assessment, a 3-day clinical assessment is essential to predict the prognosis of 14-day mortality.

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Worldwide variation in Pseudomonas associated ventilator associated pneumonia. A meta-regression

PURPOSE

The objective here is to define the extent and possible reasons for geographic variation in Pseudomonas aeruginosa associated with Ventilator Associated Pneumonia (VAP).

METHODS

A random effects meta-regression model of Pseudomonas associated VAP incidence within the published literature was undertaken incorporating group level factors such trauma admission, year of publication and use of bronchoscopic sampling towards VAP diagnosis.

RESULTS

Pseudomonas associated VAP incidence was reported in 162 studies from seven worldwide regions published over 30 years. The highest incidence is among reports from the Middle East and Mediterranean being respectively 6.8; 5.2-9.0 (mean; 95% CI) and 6.9; 5.4-8.8 per 1000 mechanical ventilation (MV) days, versus that from North American ICU's (3.7; 2.3-5.9). In a meta-regression model, the variation in the incidence of Pseudomonas associated VAP was not significantly associated with bronchoscopic sampling in the diagnosis of VAP (p = 0.12) nor with admission to a trauma ICU (p = 0.13).

CONCLUSION

Pseudomonas associated VAP incidence among reports from six geographic regions worldwide varies by less than twofold with some decline by year of publication. Trauma ICU admission is a significant factor underlying variations in incidence of VAP overall but not Pseudomonas associated VAP.

Characterizing non-linear effects of hospitalisation duration on antimicrobial resistance in respiratory isolates: an analysis of a prospective nationwide surveillance system

OBJECTIVES

Our objective was to systematically study the influence of length of hospital stay on bacterial resistance in relevant respiratory tract isolates.

METHODS

Using prospective epidemiological data from the National Swiss Antibiotic Resistance Surveillance System, susceptibility testing results for respiratory isolates retrospectively retrieved from patients hospitalised between 2008 and 2014 were compiled. Generalized additive models were used to illustrate resistance rates relative to hospitalisation duration and to adjust for co-variables.

RESULTS

In all, 19 622 isolates of six relevant and predominant species were included. Resistance patterns for the predominant species showed a species-specific and antibiotic-resistance-specific profile in function of hospitalisation duration. The oxacillin resistance profile in Staphylococcus aureus isolates was constantly increasing (monophasic). The pattern of resistance to cefepime in Pseudomonas aeruginosa was biphasic with a decreasing resistance rate for the first 5 days of hospitalisation and an increase for days 6-30. A different biphasic pattern occurred in Escherichia coli regarding amoxicillin-clavulanic acid resistance: odds/day increased for the first 7 days of hospitalisation and then remained stable for days 8-30. In the adjusted models epidemiological characteristics such as age, ward type, hospital type and linguistic region were identified as relevant co-variables for the resistance rates. The contribution of these confounders was specific to the individual species/antibiotic resistance models.

CONCLUSIONS

Resistance rates do not follow a dichotomic pattern (early versus late nosocomial) as suggested by current hospital-acquired pneumonia treatment guidelines. Duration of hospitalisation rather appears to have a more complex and non-linear relationship with bacterial resistance in hospital-acquired pneumonia, also depending on host and environmental factors.

High incidence of post-injury pneumonia in intensive care-treated trauma patients

INTRODUCTION

Trauma patients are susceptible to post-injury infections. We investigated the incidence, as well as risk factors for development of pneumonia in intensive care unit (ICU)-treated trauma patients. In addition, we report pathogens identified in patients that developed pneumonia.

METHODS

The study cohort consisted of 322 trauma patients admitted to the ICU at a level-one trauma centre following initial resuscitation. Patients 15 years or older with an ICU stay of more than 24 h were included. We investigated pre-hospital and hospital parameters during the first 24 h after admission and their possible association with pneumonia within 10 days of ICU admission.

RESULTS

Majority of the patients were male (78%) and the median age was 41 years. The overall degree of injury was high with a median Injury Severity Score (ISS) of 24. Overall 30-day mortality was 9%. Eighty-five (26%) patients developed pneumonia during their first 10 days in the ICU. Univariate logistic regression revealed that intubation in the field, shock, Glasgow Coma Scale (GCS) 3-8, major surgery within 24 h after admission, massive transfusion and ISS > 24 were all risk factors for subsequent development of pneumonia. In the multivariable model, only GCS 3-8 was identified as an independent risk factor. In 42 out of the 85 cases of pneumonia, the diagnosis was defined by significant growth of at least one pathogen where Enterobacteriaceae and Staphylococcus aureus were the most common.

CONCLUSIONS

Pneumonia is a common complication among ICU-treated trauma patients. Reduced consciousness is an independent risk factor for development of pneumonia after severe injury.

Epidemiology and outcomes of ventilator-associated pneumonia in northern Brazil: an analytical descriptive prospective cohort study

BACKGROUND

Ventilator-associated pneumonia (VAP) is considered the most common nosocomial infection in the intensive care unit (ICU), but its features are not fully known in many hospitals in Brazil. We identified clinical and epidemiological aspects associated with VAP in an intensive care unit (ICU) in a general public hospital in northern Brazil and performed an analytical descriptive prospective cohort study.

METHODS

We analyzed data from thirty-three patients who developed VAP while in the ICU. Clinical and epidemiological data of patients were obtained and tracheal secretions were submitted to culture. Microbial isolates were identified and evaluated for resistance against antimicrobial agents by using the automated Vitek 2 system.

RESULTS

The frequency of VAP was 26.2% in patients submitted to invasive mechanical ventilation for at least 48 hours, and death occurred in 78.8% of cases. Only the presence of comorbidity showed a significant association (P = 0.029) with death. The most commonly found bacteria were Pseudomonas aeruginosa, Acinetobacter spp., and Enterobacteriaceae. We also found a frequency of 54.5% of multiresistant bacteria associated with VAP, and previous antibiotic therapy was used in 97% of patients.

CONCLUSIONS

VAP in our ICU presented with a high frequency and was mainly caused by multiresistant bacteria. Implementation of rational protocols for the use of antibacterial agents and rapid delivery of culture and susceptibility test results are essential. This may help decrease VAP-related mortality rates by multiresistant bacteria in the ICU.