Hospital-acquired pneumonia: epidemiology, etiology, and treatment

A 7-year study of severe hospital-acquired pneumonia requiring ICU admission

OBJECTIVE

To examine the characteristics, prognostic factors, and outcome of patients with severe hospital-acquired pneumonia admitted to the ICU.

DESIGN AND SETTING

Prospective observational clinical study in two medical-surgical ICUs with 16 and 20 beds

PATIENTS AND PARTICIPANTS

During a 7-year period all hospitalized patients requiring admission to either ICU for hospital-acquired pneumonia were followed up.

MEASUREMENTS AND RESULTS

We diagnosed 96 episodes of severe hospital-acquired pneumonia, and in 67 cases a causal diagnosis was made. Most episodes were late-onset pneumonia. Gram-negative micro-organisms were isolated in 51% of episodes diagnosed, and Pseudomonas aeruginosa was the most frequent pathogen isolated (24%). Clearly significant variations happened between hospitals, particularly affecting the incidence of Aspergillus spp. and Legionella pneumophila. Forty-nine patients developed septic shock (51%). Fifty-one patients died (53%). Aspergillosis and pneumonia due to P. aeruginosa were associated with the highest mortality. Septic shock (OR: 14.27) and chronic obstructive pulmonary disease (OR: 6.11) were independently associated with a poor prognosis.

CONCLUSIONS

Patients with severe hospital-acquired pneumonia admitted to the ICU present high mortality. The presence of septic shock and chronic obstructive pulmonary disease in conjunction with specific microorganisms are associated with a poor prognosis. Local epidemiological data combined with a patient-based approach may allow a more accurate therapy decision making.

Incidence of adult immunization for influenza and pneumonia in a preadmission testing unit

Health care-associated (nosocomial) infection is now more common in surgical patients than surgical-site or wound infection. Elderly patients and those having abdominal, neck, cardiac, or other thoracic procedures are at the highest risk. Pneumococcal pneumonia and influenza are the fifth leading cause of mortality in the elderly population. In the United States, only 54% of persons older than 65 years have received a pneumococcal vaccine, whereas approximately 67% have been immunized for influenza. In this study, interviews were conducted with 160 elderly patients seen in the preadmission testing unit of a large community hospital. Results showed immunization rates of 57% for pneumonia and 76% for influenza. Similar to findings of previous studies, minorities were less likely to be immunized than whites. Of those who were not immunized for pneumonia or could not recall their immunization status, 71% stated they had not been offered immunization. Sixty-four percent stated they would take the vaccine to prevent pneumonia if it were offered. Of those patients who were not immunized for influenza, 54% had not been offered this protection and 41% stated they would take the influenza vaccine if offered. Although vaccination rates of participants in the present study surpassed the 1998 national baseline for noninstitutionalized adults, there is much opportunity for improvement. Perianesthesia nurses have an important role in reducing surgical patients' risks of developing health care-associated pneumonia and invasive bacteremia by assessing the patient's immunization status and being proactive in helping surgical patients obtain appropriate vaccinations. Routine documentation of a vaccination history for pneumococcal pneumonia and influenza during preadmission testing and use of a standard protocol for educating and immunizing those who lack this protection are strategies that can be easily implemented by nurses practicing in perianesthesia settings such as ambulatory surgical sites and preadmission testing units. This practice would foster achievement of the Healthy People 2010 goal of 90% vaccination rates for persons at high risk for these deadly diseases.

Aerobic Gram-negative Bacillary Pneumonia

Gram-negative bacilli (GNB) are a common cause of severe hospital-acquired pneumonia. Due to changes in the health care environment and selective antimicrobial pressure, these bacteria also are becoming a more common cause of pneumonia in venues outside of the traditional hospital setting and are increasingly resistant to antimicrobial agents. Risk factors for acquisition of GNB allow the clinician to efficiently identify patients who are likely to have pneumonia due to these pathogens. Available diagnostic techniques have a limited capacity to accurately detect GNB pulmonary infection. Yet, a pathogen specific diagnosis and knowledge of local resistance patterns are quintessential elements in formulating an effective treatment plan. This article reviews the epidemiologic characteristics, pathogenesis, and current management issues of GNB pneumonia.

Pulmonary administration of perfluorodecaline- gentamicin and perfluorodecaline- vancomycin emulsions

The aim of this study was to examine pharmacokinetics and pulmonary antibiotic tissue concentrations (PATC) of gentamicin and vancomycin after intrapulmonary administration of a perfluorodecaline (PFD)-gentamicin and a PFD-vancomycin emulsion during partial liquid ventilation (PLV). PLV was initiated in 19 healthy rabbits and 18 surfactant-depleted rabbits. The animals were randomized to receive either 5 mg/kg gentamicin and 15 mg/kg vancomycin intravenously, or 5 mg/kg gentamicin intrapulmonary, or 15 mg/kg vancomycin intrapulmonary. Antibiotic plasma levels were measured after 15, 30, 45, and 60 min, and hourly thereafter. After 5 h animals were sacrificed and lungs were removed to evaluate PATC and histology. PATC were significantly higher after intrapulmonary administration of both gentamicin and vancomycin. In healthy rabbits, peak plasma concentrations were lower and 5 h plasma concentrations were higher after intrapulmonary administration, whereas plasma concentrations were not different in surfactant-depleted rabbits. There were no differences in lung histology, hemodynamics, lung mechanics, or gas exchange between the treatment groups. We conclude that during PLV, higher PATC can be achieved after intrapulmonary administration of PFD-antibiotic emulsions compared with intravenous administration of the same dose without apparent short-term adverse effects. We speculate that intrapulmonary antibiotic administration during PLV may be beneficial in treating severe pneumonia.

The occurrence of ventilator-associated pneumonia in a community hospital: risk factors and clinical outcomes

STUDY OBJECTIVES

To prospectively identify the occurrence of ventilator-associated pneumonia (VAP) in a community hospital, and to determine the risk factors for VAP and the influence of VAP on patient outcomes in a nonteaching institution.

DESIGN

Prospective cohort study.

SETTING

A medical ICU and a surgical ICU in a 500-bed private community nonteaching hospital: Missouri Baptist Hospital.

PATIENTS

Between March 1998 and December 1999, all patients receiving mechanical ventilation who were admitted to the ICU setting were prospectively evaluated.

INTERVENTION

Prospective patient surveillance and data collection.

RESULTS

During a 22-month period, 3,171 patients were admitted to the medical and surgical ICUs. Eight hundred eighty patients (27.8%) received mechanical ventilation. VAP developed in 132 patients (15.0%) receiving mechanical ventilation. Three hundred one patients (34.2%) who received mechanical ventilation died during hospitalization. Logistic regression analysis demonstrated that tracheostomy (adjusted odds ratio [AOR], 6.71; 95% confidence interval [CI], 3.91 to 11.50; p < 0.001), multiple central venous line insertions (AOR, 4.20; 95% CI, 2.72 to 6.48; p < 0.001), reintubation (AOR, 2.88; 95% CI, 1.78 to 4.66; p < 0.001), and the use of antacids (AOR, 2.81; 95% CI, 1.19 to 6.64; p = 0.019) were independently associated with the development of VAP. The hospital mortality of patients with VAP was significantly greater than the mortality of patients without VAP (45.5% vs 32.2%, respectively; p = 0.004). The occurrence of bacteremia, compromised immune system, higher APACHE (acute physiology and chronic health evaluation) II scores, and older age were identified as independent predictors of hospital mortality.

CONCLUSIONS

These data suggest that VAP is a common nosocomial infection in the community hospital setting. The risk factors for the development of VAP and risk factors for hospital mortality in a community hospital are similar to those identified from university-affiliated hospitals. These risk factors can potentially be employed to develop local strategies for the prevention of VAP.

CLINICAL IMPLICATIONS

ICU clinicians should be aware of the risk factors associated with the development of VAP and the impact of VAP on clinical outcomes. More importantly, they should cooperate in the development of local multidisciplinary strategies aimed at the prevention of VAP and other nosocomial infections.

Experience with a clinical guideline for the treatment of ventilator-associated pneumonia

OBJECTIVE

To evaluate a clinical guideline for the treatment of ventilator-associated pneumonia.

DESIGN

Prospective before-and-after study design.

SETTING

A medical intensive care unit from a university-affiliated, urban teaching hospital.

PATIENTS

Between April 1999 and January 2000, 102 patients were prospectively evaluated.

INTERVENTIONS

Prospective patient surveillance, data collection, and implementation of an antimicrobial guideline for the treatment of ventilator-associated pneumonia.

MEASUREMENTS AND MAIN RESULTS

The main outcome evaluated was the initial administration of adequate antimicrobial treatment as determined by respiratory tract cultures. Secondary outcomes evaluated included the duration of antimicrobial treatment for ventilator-associated pneumonia, hospital mortality, intensive care unit and hospital lengths of stay, and the occurrence of a second episode of ventilator-associated pneumonia. Fifty consecutive patients with ventilator-associated pneumonia were evaluated in the before period and 52 consecutive patients with ventilator-associated pneumonia were evaluated in the after period. Severity of illness using Acute Physiology and Chronic Health Evaluation II (25.8 +/- 5.7 vs. 25.4 +/- 8.1, p =.798) and the clinical pulmonary infection scores (6.6 +/- 1.0 vs. 6.9 +/- 1.2, p =.105) were similar for patients during the two treatment periods. The initial administration of adequate antimicrobial treatment was statistically greater during the after period compared with the before period (94.2% vs. 48.0%, p <.001). The duration of antimicrobial treatment was statistically shorter during the after period compared with the before period (8.6 +/- 5.1 days vs. 14.8 +/- 8.1 days, p <.001). A second episode of ventilator-associated pneumonia occurred statistically less often among patients in the after period (7.7% vs. 24.0%, p =.030).

CONCLUSIONS

The application of a clinical guideline for the treatment of ventilator-associated pneumonia can increase the initial administration of adequate antimicrobial treatment and decrease the overall duration of antibiotic treatment. These findings suggest that similar types of guidelines employing local microbiological data can be used to improve overall antibiotic utilization for the treatment of ventilator-associated pneumonia.

Continuous versus intermittent administration of ceftazidime in intensive care unit patients with nosocomial pneumonia

A prospective, randomized pilot study was undertaken to compare the efficacy of continuous versus intermittent ceftazidime in ICU patients with nosocomial pneumonia. Ceftazidime was administered either as a 3 g/day continuous infusion (CI) or an intermittent infusion (II) of 2 g every 8 h. In addition, all patients received concomitant once-daily tobramycin. The demographics of the evaluable patients (n = 35) were similar between the groups: age (years), CI 46 +/- 16, II 56 +/- 20; Apache score, CI 14 +/- 4, II 16 +/- 6; time (days) from admission to diagnosis, CI 9 +/- 6, II 9 +/- 6. Clinical efficacy, defined as cure/improvement was similar between groups [n (%), CI 16/17 (94), II 15/18 (83)], while microbiological response was also comparable [n (%), CI 10/13 (76), II 12/15 (80)]. Minimal inhibitory concentrations (MICs) for all isolates were measured throughout the treatment course; there was no development of resistance during therapy for either regimen. While limited clinical data exist, our results suggest that the use of ceftazidime by CI administration maintains clinical efficacy, optimizes the pharmacodynamic profile and uses less antibiotic compared with the standard 2 g every 8 h intermittent dosing regimen.

Postoperative nosocomial pneumonia: nurse-sensitive interventions

Nosocomial pneumonia (NP) is well documented as the second most common nosocomial infection. It is now more common in surgical patients than surgical-site or wound infection. Healthcare implications of NP include not only increased patient morbidity and mortality, but also increased use of healthcare resources. The advanced practice nurse plays an integral role in the prevention and minimization of NP across healthcare settings. This article focuses on postoperative NP after abdominal, cardiac, or thoracic surgery in the non-mechanically ventilated patient and discusses the diagnostic assessment, risk factors, and potential nurse-sensitive interventions to prevent or minimize this complication. Ideas for potential nursing research related to these risk factors are described.

Linezolid (PNU-100766) versus vancomycin in the treatment of hospitalized patients with nosocomial pneumonia: a randomized, double-blind, multicenter study

Linezolid, the first oxazolidinone, is active against gram-positive bacteria, including multidrug-resistant strains. This multinational, randomized, double-blind, controlled trial compared the efficacy, safety, and tolerability of linezolid with vancomycin in the treatment of nosocomial pneumonia. A total of 203 patients received intravenous linezolid, 600 mg twice daily, plus aztreonam, and 193 patients received vancomycin, 1 g intravenously twice daily, plus aztreonam for 7-21 days. Clinical and microbiological outcomes were evaluated at test of cure 12-28 days after treatment. Clinical cure rates (71 [66.4%] of 107 for linezolid vs. 62 [68.1%] of 91 for vancomycin) and microbiological success rates (36 [67.9%] of 53 vs. 28 [71.8%] of 39, respectively) for evaluable patients were equivalent between treatment groups. Eradication rates of methicillin-resistant Staphylococcus aureus and safety evaluations were similar between treatment groups. Resistance to either treatment was not detected. Linezolid is a well-tolerated, effective treatment for adults with gram-positive nosocomial pneumonia.

Inadequate antimicrobial treatment: an important determinant of outcome for hospitalized patients

Inadequate antimicrobial treatment, generally defined as microbiological documentation of an infection that is not being effectively treated, is an important factor in the emergence of infections due to antibiotic-resistant bacteria. Factors that contribute to inadequate antimicrobial treatment of hospitalized patients include prior antibiotic exposure, use of broad-spectrum antibiotics, prolonged length of stay, prolonged mechanical ventilation, and presence of invasive devices. Strategies to minimize inadequate treatment include consulting an infectious disease specialist, using antibiotic practice guidelines, and identifying quicker methods of microbiological identification. In addition, clinicians should determine the prevailing pathogens that account for the community-acquired and nosocomial infections identified in their hospitals. Clinicians can improve antimicrobial treatment by using empirical combination antibiotic therapy based on individual patient characteristics and the predominant bacterial flora and their antibiotic susceptibility profiles. This broad-spectrum therapy can then be narrowed when initial culture results are received. Further study evaluating the use of antibiotic practice guidelines and strategies to reduce inadequate treatment is necessary to determine their impact on patient outcomes.

Antibiotic agents in the elderly

Changes that occur in the pharmacology of drugs in the elderly must be considered in the use of antimicrobial agents. Although absorption of orally administered drugs is not affected in a significant way, renal function decreases, drug-drug interactions increase, compliance with regimens may be decreased, and drug toxicity is increased. The most frequent infections occurring in the elderly are pneumonia, urinary tract infection, and soft-tissue infection. CDAD is usually a complication of antibiotic therapy. Pneumonia can be categorized as community-acquired, LTCF, and hospital-acquired. Therapeutic approaches vary according to which of these sites is involved. Urinary tract infection is divided into upper tract infection, lower tract infection, and asymptomatic bacteriuria. Upper tract infection is treated for a longer period than lower tract infection; with few exceptions, asymptomatic bacteriuria is usually not treated. Soft-tissue infection is usually caused by an infected pressure ulcer or cellulitis (which may be a complication of a diabetic foot ulcer or an ulcer due to peripheral vascular disease). These infections have different microbial causes and require different therapeutic approaches.

Frequency of occurrence and antimicrobial susceptibility patterns for pathogens isolated from latin american patients with a diagnosis of pneumonia: results from the SENTRY antimicrobial surveillance program (1998)

The correct empiric choice of antimicrobial therapy in the treatment of pneumonia in hospitalized patients has established itself as a major therapeutic challenge to clinicians. Selection of an inappropriate antimicrobial agent could lead to increased rates of mortality and morbidity. Characteristics of pathogens responsible for this infection such as species prevalence, overall antimicrobial resistance rates, and mechanisms of detected resistance could serve as an invaluable resource to clinicians in making such therapeutic selections. This report addresses the aforementioned problems/needs by analysis of 712 strains isolated from the lower respiratory tract of patients hospitalized with a diagnosis of pneumonia in 10 Latin American medical centers in the SENTRY Antimicrobial Surveillance Program (1998). The four most frequently isolated pathogens (no/% of total) were: Pseudomonas aeruginosa (191/26.8%), Staphylococcus aureus (171/24.0%), Klebsiella spp. (86/12.1%), and Acinetobacter spp. (75/10.5%); representing nearly 75.0% of all isolates. More than 40 antimicrobial agents (23 reported) were tested against these isolates by reference broth microdilution methodology, and susceptibility profiles were established. The nonfermentative Gram-negative bacteria (P. aeruginosa and Acinetobacter spp.) exhibited high levels of resistance to the agents tested. Amikacin (77.5% susceptible) was the most active drug tested against P. aeruginosa 50.0% against the Acinetobacter spp. isolates. Based on published interpretive criteria, over 22.0% of the Klebsiella spp. and 12.5% of the Escherichia coli were classified as extended spectrum beta-lactamase (ESBL) producers. Of the cephalosporin class compounds tested against the Klebsiella spp. and E. coli isolates, cefepime demonstrated the highest rates of susceptibility (84.9% and 91.7%, respectively). This compound also fared well against the Enterobacter spp. isolates, inhibiting 88.2% of the isolates tested, many of which were resistant to ceftazidime and ceftriaxone. Resistance to oxacillin among the S. aureus isolates was nearly 50. 0%, with vancomycin, teicoplanin, and the streptogramin combination quinupristin/dalfopristin inhibiting all isolates. Several clusters of multiply resistant organisms were also observed, and further characterization by ribotyping and pulsed-field gel electrophoresis established possible patient-to-patient spread. The results of this study indicate that rates of resistance among respiratory tract pathogens continue to rise in Latin America, with specific concerns for the high prevalence of nonfermentative Gram-negative bacteria isolated, oxacillin resistance rates in S. aureus, and the epidemic dissemination of multiply-resistant strains in several medical centers. International surveillance programs (SENTRY) should assist in the control of escalating antimicrobial resistance in this geographic area.

A comparative analysis of patients with early-onset vs late-onset nosocomial pneumonia in the ICU setting

STUDY OBJECTIVE

To compare the clinical outcomes of critically ill patients developing early-onset nosocomial pneumonia (NP; ie, within 96 h of ICU admission) and late-onset NP (ie, occurring after 96 h of ICU admission).

DESIGN

Prospective cohort study.

SETTING

A medical ICU and a surgical ICU from a university-affiliated urban teaching hospital.

PATIENTS

Between July 1997 and November 1998, 3, 668 patients were prospectively evaluated.

INTERVENTION

Prospective patient surveillance and data collection.

RESULTS

Four hundred twenty patients (11.5%) developed NP. Early-onset NP was observed in 235 patients (56.0%), whereas 185 patients (44.0%) developed late-onset NP. Among patients with early onset NP, 114 patients (48. 5%) spent at least 24 h in the hospital prior to ICU admission, compared to 57 patients (30.8%) with late-onset NP (p = 0.001). One hundred eighty-three patients (77.9%) with early-onset NP received antibiotics prior to the development of NP, as compared to 162 patients (87.6%) with late-onset NP (p = 0.010). The most common pathogens associated with early-onset NP were Pseudomonas aeruginosa (25.1%), oxacillin-sensitive Staphylococcus aureus (OSSA; 17.9%), oxacillin-resistant S aureus (ORSA; 17.9%), and Enterobacter species (10.2%). P aeruginosa (38.4%), ORSA (21.1%), Stenotrophomonas maltophilia (11.4%), OSSA (10.8%), and Enterobacter species (10.3%) were the most common pathogens associated with late-onset NP. The ICU length of stay was significantly longer for patients with early-onset NP (10.3 +/- 8.3 days; p < 0.001) and late-onset NP (21. 0 +/- 13.7 days; p < 0.001), as compared to patients without NP (3.5 +/- 3.2 days). Hospital mortality was significantly greater for patients with early-onset NP (37.9%; p = 0.001) and late-onset NP (41.1%; p = 0.001) compared to patients without NP (13.1%).

CONCLUSIONS

Both early-onset and late-onset NP are associated with increased hospital mortality rates and prolonged lengths of stay. The pathogens associated with NP were similar for both groups. This may be due, in part, to the prior hospitalization and use of antibiotics in many patients developing early-onset NP. These data suggest that P aeruginosa and ORSA can be important pathogens associated with early-onset NP in the ICU setting. Additionally, clinicians should be aware of the common microorganisms associated with both early-onset NP and late-onset NP in their hospitals in order to avoid the administration of inadequate antimicrobial treatment.