The antibiotic treatment of community-acquired, atypical, and nosocomial pneumonias

Mycoplasma Pneumoniae Associated with Stevens Johnson Syndrome

We describe a case of Mycoplasma pneumoniae chest infection associated with Stevens Johnson syndrome. The patient had extensive epidermal bullous vesicles, oropharyngeal and genital ulceration and required prolonged ventilation due to respiratory failure. Mycoplasma pneumoniae infections are often asymptomatic but can involve multiple organ systems. Respiratory tract involvement is generally benign though 3 to 10% of patients develop clinical pneumonia. Secondary skin reactions are common (20 to 25%), although few patients infected develop Stevens Johnson syndrome. It has been suggested that Mycoplasma pneumoniae may be the most common infectious cause of Stevens Johnson syndrome.

Can we predict which patients with community-acquired pneumonia are likely to have positive blood cultures?

BACKGROUND

Blood cultures (BC) are commonly ordered during the initial assessment of patients with community-acquired pneumonia (CAP), yet their yield remains low. Selective use of BC would allow the opportunity to save healthcare resources and avoid patient discomfort. The study was to determine what demographic and clinical factors predict a greater likelihood of a positive blood culture result in patients diagnosed with CAP.

METHODS

A structured retrospective systematic chart audit was performed to compare relevant demographic and clinical details of patients admitted with CAP, in whom blood culture results were positive, with those of age, sex, and date-matched control patients in whom blood culture results were negative.

RESULTS

On univariate analysis, eight variables were associated with a positive BC result. After logistic regression analysis, however, the only variables statistically significantly associated with a positive BC were WBC less than 4.5 × 10(9)/L [likelihood ratio (LR): 7.75, 95% CI=2.89-30.39], creatinine >106 μmol/L (LR: 3.15, 95%CI=1.71-5.80), serum glucose<6.1 mmol/L (LR: 2.46, 95%CI=1.14-5.32), and temperature > 38 °C (LR: 2.25, 95% CI =1.21-4.20). A patient with all of these variables had a LR of having a positive BC of 135.53 (95% CI=25.28-726.8) compared to patients with none of these variables.

CONCLUSIONS

Certain clinical variables in patients with CAP admitted to hospitals do appear to be associated with a higher probability of a positive yield of BC, with combinations of these variables increasing this likelihood. We have identified a subgroup of CAP patients in whom blood cultures are more likely to be useful.

Clinical practice guidelines for hospital-acquired pneumonia and ventilator-associated pneumonia in adults

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are important causes of morbidity and mortality, with mortality rates approaching 62%. HAP and VAP are the second most common cause of nosocomial infection overall, but are the most common cause documented in the intensive care unit setting. In addition, HAP and VAP produce the highest mortality associated with nosocomial infection. As a result, evidence-based guidelines were prepared detailing the epidemiology, microbial etiology, risk factors and clinical manifestations of HAP and VAP. Furthermore, an approach based on the available data, expert opinion and current practice for the provision of care within the Canadian health care system was used to determine risk stratification schemas to enable appropriate diagnosis, antimicrobial management and nonantimicrobial management of HAP and VAP. Finally, prevention and risk-reduction strategies to reduce the risk of acquiring these infections were collated. Future initiatives to enhance more rapid diagnosis and to effect better treatment for resistant pathogens are necessary to reduce morbidity and improve survival.

Procalcitonin-guided antibiotic use versus a standard approach for acute respiratory tract infections in primary care: study protocol for a randomised controlled trial and baseline characteristics of participating general practitioners [ISRCTN73182671]

BACKGROUND

Acute respiratory tract infections (ARTI) are among the most frequent reasons for consultations in primary care. Although predominantly viral in origin, ARTI often lead to the prescription of antibiotics for ambulatory patients, mainly because it is difficult to distinguish between viral and bacterial infections. Unnecessary antibiotic use, however, is associated with increased drug expenditure, side effects and antibiotic resistance. A novel approach is to guide antibiotic therapy by procalcitonin (ProCT), since serum levels of ProCT are elevated in bacterial infections but remain lower in viral infections and inflammatory diseases. The aim of this trial is to compare a ProCT-guided antibiotic therapy with a standard approach based on evidence-based guidelines for patients with ARTI in primary care.

METHODS/DESIGN

This is a randomised controlled trial in primary care with an open intervention. Adult patients judged by their general practitioner (GP) to need antibiotics for ARTI are randomised in equal numbers either to standard antibiotic therapy or to ProCT-guided antibiotic therapy. Patients are followed-up after 1 week by their GP and after 2 and 4 weeks by phone interviews carried out by medical students blinded to the goal of the trial. Exclusion criteria for patients are antibiotic use in the previous 28 days, psychiatric disorders or inability to give written informed consent, not being fluent in German, severe immunosuppression, intravenous drug use, cystic fibrosis, active tuberculosis, or need for immediate hospitalisation. The primary endpoint is days with restrictions from ARTI within 14 days after randomisation. Secondary outcomes are antibiotic use in terms of antibiotic prescription rate and duration of antibiotic treatment in days, days off work and days with side-effects from medication within 14 days, and relapse rate from the infection within 28 days after randomisation.

DISCUSSION

We aim to include 600 patients from 50 general practices in the Northwest of Switzerland. Data from the registry of the Swiss Medical Association suggests that our recruited GPs are representative of all eligible GPs with respect to age, proportion of female physicians, specialisation, years of postgraduate training and years in private practice.

Efficacy and safety of oral and early-switch therapy for community-acquired pneumonia: a randomized controlled trial

PURPOSE

We sought to determine the safety, efficacy, and cost of oral therapy for patients with community-acquired pneumonia. In patients with nonsevere pneumonia, conventional (parenteral) treatment was compared with the oral route; in patients with severe pneumonia, conventional treatment was compared with early switch from parenteral to oral therapy.

SUBJECTS AND METHODS

We randomly assigned 85 hospitalized patients with nonsevere pneumonia to one of two groups: 41 received oral antimicrobials from admission, and 44 received parenteral antimicrobials until they had been afebrile for 72 hours before switching to oral treatment. We randomly assigned 103 patients with severe pneumonia who had initially been treated with parenteral antimicrobials to one of two groups: 48 were switched to oral therapy after 48 hours of treatment (early switch), and 55 received a full 10-day course of parenteral antibiotics.

RESULTS

Among patients with nonsevere pneumonia, there were no deaths in the oral treatment group, and one death (2%) in the parenteral treatment group (95% confidence interval [CI] for between-group [oral minus parenteral] difference: -7% to 2%, P = 0.3). The time to resolution of morbidity was < or =5 days in 34 (83%) patients in the oral treatment group and 39 (88%) patients in the parenteral treatment group (P = 0.5); there were treatment failures in 4 (10%) patients in the oral treatment group and 14 (32%) patients in the parenteral treatment group (P = 0.02). Among patients with severe pneumonia, there was one (2%) death in the early-switch group and no deaths in the full course of parenteral antibiotics groups (95% CI for between-group [early switch vs. full course] difference: -2% to 6%, P = 0.5). The time to resolution of morbidity was < or =5 days in 38 (79%) patients in the early-switch group and 41 (75%) in the full-course group (P = 0.3). There were 12 (25%) treatment failures in the early-switch group and 13 (24%) in the full-course group (P = 0.9). There were fewer adverse events in the oral and early-switch groups, primarily due to lower rates of infusion-related phlebitis. Significant cost savings, mainly due to a shorter hospitalization, occurred among patients with severe pneumonia in the early-switch group.

CONCLUSION

Inpatients with nonsevere community-acquired pneumonia can be effectively and safely treated with oral antimicrobials from the time of admission, whereas those with severe pneumonia can be treated with early-switch therapy.

Management of patients with infectious diseases in an emergency department observation unit

Pneumonia, cellulitis, and pyelonephritis are discussed in this review because they are the most common infections requiring hospital care, and they all have significant death or complication rates and broad differential diagnoses. They also demonstrate many of the considerations that could be applied to other infections appropriate for OU care. Table 11 lists additional infections that are good candidates for OU care. A key to successful OU management of infection is early consultation with the primary care physicians and appropriate specialists when one is setting up the unit, designing its guidelines, and when treating specific patients. Because individual patient outcomes are not predictable, increasing the absolute numbers treated and successfully discharged from observation can necessarily increase the percentage of OU patients that are hospitalized. In essence, a group who would be hospitalized from the ED is transferred to observation status, where most avoid hospital admission. Because some patients fail to respond, develop complications, or demonstrate alternative diagnoses, many troubles can be avoided when the primary care and specialist physicians have collaborated in the observation treatment decisions. These guidelines have been presented as a starting point. It is clear that more research targeted at this group of patients is required to refine current practice. As for everything else in medicine, there is no doubt that many of the specific recommendations made here will become obsolete in no time.

Community-acquired pneumonia. Diagnostic and therapeutic approach

Optimal empiric therapy of CAP is with appropriate monotherapy (e.g., doxycycline, levofloxacin). Combination therapy is problematic because of potential side effects and high cost. Empiric coverage should have a high degree of activity against both typical and atypical pathogens. The antibiotic selected should have an excellent side-effect profile and be relatively inexpensive. Clinicians should be selective in their choice of antibiotic for CAP and choose an antimicrobial that has little or no resistance potential, is relatively inexpensive, and permits i.v.-to-PO switch monotherapy.

Nosocomial pneumonia. Diagnostic and therapeutic considerations

Many patients with presumed nosocomial pneumonia probably have infiltrates on the chest radiograph, fever, and leukocytosis resulting from noninfectious causes. Because of the high mortality and morbidity associated with nosocomial pneumonias, however, most clinicians treat such patients with a 2-week empiric trial of antibiotics. Before therapy is initiated, the clinician should rule out other causes of pulmonary infiltrates, fever, and leukocytosis that mimic a nosocomial pneumonia (e.g., pre-existing interstitial lung disease, primary or metastatic lung carcinomas, pulmonary emboli, pulmonary drug reactions, pulmonary hemorrhage, collagen vascular disease affecting the lungs, or congestive heart failure). If these disorders can be eliminated from diagnostic consideration, a 2-week trial of empiric monotherapy is indicated. The clinician should treat cases of presumed nosocomial pneumonia as if P. aeruginosa were the pathogen. Although P. aeruginosa is not the most common cause of nosocomial pneumonia, it is the most virulent pulmonary pathogen associated with nosocomial pneumonia. Coverage directed against P. aeruginosa is effective against all other aerobic gram-negative bacillary pathogens causing hospital-acquired pneumonia. The clinician should select an antibiotic for empiric monotherapy that is highly effective against P. aeruginosa, has a good side-effect profile, has a low resistance potential, and is relatively inexpensive in terms of its cost to the institution. The preferred agents for empiric monotherapy for nosocomial pneumonia are cefepime, meropenem, and piperacillin. Single organisms are responsible for nosocomial pneumonia, not multiple pathogens. S. aureus rarely, if ever, causes nosocomial pneumonia but is mentioned frequently in studies based on cultures of respiratory tract secretions. S. aureus, unless accompanied by a necrotizing pneumonia with rapid cavitation within 72 hours, in the sputum indicates colonization rather than infection and should not be addressed therapeutically. Antibiotics associated with a high resistance potential should not be used as monotherapy or included in combination therapy regimens (i.e., ceftazidime, ciprofloxacin, imipenem, or gentamicin). Combination therapy is more expensive than monotherapy and is indicated only when P. aeruginosa is extremely likely, based on its characteristic clinical presentation, or is proved by tissue biopsy. Therapy should not be based on respiratory secretion cultures regardless of technique. Optimal combination regimens include cefepime or meropenem plus levofloxacin or piperacillin or aztreonam or amikacin. Nosocomial pneumonias usually are treated for 14 days. Lack of radiographic or clinical response to appropriate empiric nosocomial pneumonia monotherapy after 14 days suggests an alternate diagnosis. In these patients, a tissue biopsy specimen should be obtained to determine the cause of the persistence of pulmonary infiltrates unresponsive to appropriate antimicrobial therapy.

Differential diagnosis between community-acquired pneumonia and non-pneumonia diseases of the chest in the emergency ward

Background: The differential diagnosis of community-acquired pneumonia and some non-pneumonia diseases involving the chest may sometimes be cumbersome. Adding some objective variables to the diagnostic strategy may be helpful.We evaluated the main objective variables that are usually available in the emergency ward and that may be valuable in this differential diagnosis. Methods: We recorded epidemiological, clinical, and analytical data, as well as that obtained from physical examination, from 284 consecutive patients diagnosed in the emergency ward as having community-acquired pneumonia. The diagnosis was reviewed by the investigators applying pre-set diagnostic criteria. Statistical analysis was then performed comparing data from patients with a definitive diagnosis of community-acquired pneumonia with those with a final diagnosis of non-pneumonia disease excluding acute exacerbations of chronic bronchitis. Results: In the univariate analysis, C-reactive protein (difference of means 93 mg/l; 95% C.I. 47, 140), erythrocyte sedimentation rate (d.m. 19 mm/h; 95% C.I. 3, 35), leukocyte count (d.m. 3.5x10(9)/l; 95% C.I. 0.5, 6.4), and temperature (d.m. 0.5 degrees C; 95% C.I. 0.1, 0.9) discriminated between community-acquired pneumonia and non-pneumonia diseases. In the multivariate analysis, only C-reactive protein remained in the equation. Conclusions: C-reactive protein, erythrocyte sedimentation rate, leukocyte count, and temperature were measurable variables that proved to be useful in the differential diagnosis between community-acquired pneumonia and non-pneumonia diseases. C-reactive protein appears to be the most suitable for this purpose.

The cost-effectiveness of a hypothetical respiratory syncytial virus vaccine in the elderly

To determine if specific levels of vaccine cost and effectiveness exist that would support eventual respiratory syncytial virus (RSV) vaccine use in the elderly, a cost-effectiveness study was conducted comparing yearly administration of a hypothetical RSV vaccine among the 65-year-old US cohort to medical management of disease. Using base case assumptions - including a vaccine effectiveness against RSV-related hospitalization and death of 80% and a vaccine cost of US$33 - vaccine would result in 0.7 additional days of healthy life at a cost of US$9.82 per person. The cost per quality-adjusted life-year gained equaled US$5342 and remained reasonable over a wide range of vaccine cost and effectiveness. RSV vaccine would be cost-effective for the elderly population, with cost-effectiveness ratios similar to those for influenza vaccine.

Azithromycin: single 1.5 g dose in the treatment of patients with atypical pneumonia syndrome--a randomized study

An open comparative study was undertaken in order to assess the efficacy and safety of a single dose of azithromycin in the treatment of community-acquired atypical pneumonia. A total of 100 adult patients with atypical pneumonia syndrome were randomized to receive 1.5 g of azithromycin as a single dose, or 500 mg once daily for 3 days. The presence of Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, Coxiella burnetii, and Legionella pneumophila infection was diagnosed by serological tests. Control clinical examinations were performed 72 h, 10-12 days and 4 weeks after treatment initiation. Among 96 patients (48 in each group) who were evaluable for clinical efficacy M. pneumoniae infection was confirmed in 24, C. pneumoniae in nine, C. psittaci in five, C. burnetii in six, and L. pneumophila in five. Forty-seven patients (97.9%) in each group were cured. Side effects were observed in two patients in the single-dose group, and one patient in the 3-day group. In conclusion, a single 1.5 g dose of azithromycin may be an alternative to the standard 3-day azithromycin regimen in the treatment of outpatients with atypical pneumonia syndrome.

Efficacy and safety of high dose intravenous ciprofloxacin in the treatment of bacterial pneumonia. Italian Ciprofloxacin Study Group

One hundred and fifty three hospitalized patients were enrolled in an open, prospective, multi-center study on the efficacy and safety of intravenous ciprofloxacin (400 mg i.v., b.i.d.) for acute bacterial pneumonia: 93 (63%) patients were valid for efficacy out of 148 valid for intention-to-treat analysis. The most commonly isolated organisms from 93 valid-for-efficacy patients were Pseudomonas aeruginosa (17%), Haemophilus influenzae and parainfluenzae (17%), Streptococcus aureus (14%) and Streptococcus pneumoniae (11%). Cure was achieved in 89/93 (95.7%) valid-for-efficacy patients; effective eradications were obtained in 42 (45%) and presumed eradications in 48 (52%) of the 93 patients. Mild or moderate adverse events (AE) occurred in 13/153 (8.5%) patients assessable for safety; all but one AE were rapidly reversible and only one treatment-stop (0.65%) was decided. The treatment of acute bacterial pneumonias with high-dose parenteral ciprofloxacin appears to be efficacious and well tolerated.

Programs promoting timely sequential antimicrobial therapy: an American perspective

Interventional programs promoting the timely conversion of intravenous to oral antimicrobial therapy have been reported from several hospitals in the U.S.A. and elsewhere. Factors influencing the initiation and conduct of these programs include technological advances, changes in health care delivery or reimbursement, publication of supportive clinical data and growth of clinical pharmacy services. Successful programs employ comprehensive, multidisciplinary strategies to contain antimicrobial-related expenditures using interventions based on structured criteria. Future emphasis on cost-effective drug therapy, advances in computer-based information technology and development of care maps can have favourable influences on the growth of these programs in the U.S.A.

Infections in nonleukopenic compromised hosts (diabetes mellitus, SLE, steroids, and asplenia) in critical care

Acutely ill patients who are immunocompromised but not neutropenic most commonly are: (1) diabetic; (2) on chronic high-dose steroid therapy; (3) have lupus; or (4) have impaired or absent splenic function. These patients often present in the CCU because of the severity of their infection. Differential diagnosis may be approached by first considering the patient's underlying disease, i.e., SLE. The next step in the diagnostic process is to appreciate the immune defect associated with these disorders. The nature of the immune defect determines which clinical pathogens are related to the immune defect. Pathogens are associated with a sterotyped pattern of organ involvement. The object of the diagnostic analysis is to determine the most likely organism affecting a particular organ system, given the defect in host defenses associated with the patient's underlying illness. In this way, a useful clinical diagnosis can be made rapidly, and appropriate clinical specimens obtained for diagnostic testing. Often empiric therapy must be started pending the results of diagnostic testing. In such situations, empiric therapy ordinarily is directed against the bacterial pathogens most likely to cause disease relevant to the patient's impaired defenses. Specific therapy for unusual or exotic pathogens should not be empiric and should be based on demonstration of a pathogenic role by the microorganism. In the case of miliary tuberculosis or invasive fungal disease, a case may be made for early empiric therapy to cover these organisms if there is sufficient clinical suspicion based on the presenting signs and symptoms as well as the pattern of organ involvement. As with all infections, but particularly in immunocompromised patients, the early initiation of appropriate antimicrobial therapy is essential and often life-saving.

Severe community-acquired pneumonia

Community-acquired pneumonia (CAP) is likely to be severe in the very elderly, and clinically significant in those with hepatic/ renal insufficiency, cardiopulmonary disease, or, impaired host defenses. Pathogens in mild, moderately severe, and severe CAP are the same. These pathogens determine prognosis, complications, and duration of therapy. Empiric antimicrobial therapy should be based on likely pathogens, not severity of illness which affects the potency but not spectrum of antibiotic selected.

Penicillin dosing for pneumococcal pneumonia

Most textbook authors still endorse penicillin G as the specific antibiotic of choice for pneumococcal pneumonia. However, problems with early precise etiologic diagnosis of pneumonia and the emergence of drug-resistant pneumococci cause penicillin to be seldom used for this purpose today. A third explanation for the infrequent use of penicillin is lack of clear consensus dosing guidelines. Emergence of pneumococci resistant to the newer cephalosporins and concerns about overuse of vancomycin, however, have prompted renewed interest in the development of precise, rapid methods for diagnosis of pneumococcal pneumonia with the implication that penicillin might be used more frequently. We review several issues concerning penicillin dosing: intermittent vs continuous therapy, high dose vs low dose, relationship of dose to resistance, and cost-effective pharmacology. An optimum "high-dose" regimen for life-threatening pneumococcal pneumonia in a 70-kg adult consists of a 3 million unit (mu) loading dose followed by continuous infusion of 10 to 12 mu of freshly prepared drug every 12 h. The maintenance dose should be reduced in elderly patients and in patients with renal failure according to the following formula: dose (mu/24 h = 4+[creatinine clearance divided by 7]). This regimen provides a penicillin serum level of 16 to 20 microg/mL, which should suffice for all but the most highly resistant strains (minimum inhibitory concentration > or = 4 microg/mL). Newer cephalosporins and vancomycin can be reserved for patients with suspected meningitis or endocarditis or for localities in which highly resistant pneumococci are known to be prevalent.

Radiographic pulmonary infiltrates

The finding of a pulmonary infiltrate on chest radiograph may represent a spectrum of pathologic entities in the acutely ill hospitalized adult. Timely intervention depends on the advanced practice nurse's ability to devise a differential diagnosis based on the characteristics of the infiltrate and the clinical setting. Pulmonary infiltrates are described as interstitial or alveolar, diffuse or focal. Their presentation may be chronic or acute in nature. Understanding the nuances of chest radiographic interpretation provides the foundation on which the infiltrate is described and is therefore the first step in establishing the differential diagnosis. Thorough clinical assessment and thoughtful requisition of diagnostic studies are used to discriminate the disorders found in the differential diagnosis. Using an organized approach to describe the radiographic abnormality and define its clinical context, the advanced practice nurse can efficiently establish a diagnosis so that the work of treatment may begin.

A predictive model for the treatment approach to community-acquired pneumonia in patients needing ICU admission

OBJECTIVE

To create a predictive model for the treatment approach to community-acquired pneumonia (CAP) in patients needing Intensive Care Unit (ICU) admission.

DESIGN

Multicenter prospective study.

SETTING

Twenty-six Spanish ICUs.

PATIENTS

One hundred seven patients with CAP, all of them with accurate etiological diagnosis, divided in three groups according to their etiology in typical (bacterial pneumonia), Legionella and other atypical (Mycoplasma, Chlamydia spp. and virus). For the multivariate analysis we grouped Legionella and other atypical etiologies in the same category.

METHODS

We recorded 34 variables including clinical characteristics, risk factors and radiographic pattern. We used a multivariate logistic regression analysis to find out a predictive model.

RESULTS

We have the complete data in 70 patients. Four variables: APACHE II, (categorized as a dummy variable) serum sodium and phosphorus and "length of symptoms" gave an accurate predictive model (c = 0.856). From the model we created a score that predicts typical pneumonia with a sensitivity of 90.2% and specificity 72.4%.

CONCLUSION

Our model is an attempt to help in the treatment approach to CAP in ICU patients based on a predictive model of basic clinical and laboratory information. Further studies, including larger numbers of patients, should validate and investigate the utility of this model in different clinical settings.

Fever in the intensive care unit

In the ICU, fever can be expected to accompany an extensive number of conditions of both infectious and noninfectious etiologies. It is crucial to identify the precise cause of fever, because certain conditions in either category may be life-threatening, whereas others require no treatment at all. It is important to rule out the most common infections that may be present based on historical and physical signs and symptoms and epidemiologic factors. The extent of evaluation should be based on the likelihood of the disease process being present and is highly variable for each individual patient. Therefore, "routine fever work-up" should not be advocated. If overt infection is not found upon initial evaluation, antibiotics should be withheld if possible. Alternatively, in the unstable patient, empiric therapy may be started, and if no infection is evident, it may be stopped within a reasonable time frame. In no case should prolonged antibiotics be given for presumed but unproven infection. Thorough knowledge of the more common infectious and noninfectious conditions, as well as the awareness of less frequent ones and their predisposing risk factors, is essential for adequate evaluation of the febrile ICU patient. Likewise, familiarity with the techniques used for diagnosis of these infections and their appropriate interpretation and limitations in specific instances is immensely helpful to the clinician providing appropriate care for the critically ill patient.