Pneumonia
Karlowsky JA, Thornsberry C, Jones ME, Evangelista AT, Critchley IA, Sahm DF; TRUST Surveillance Program. Factors associated with relative rates of antimicrobial resistance among Streptococcus pneumoniae in the United States: results from the TRUST Surveillance Program (1998-2002). Clin Infect Dis. 2003;36:963-970. Abstract This is a report from Tracking Resistance in the US Today (TRUST) surveillance program for 1998 through 2002. There were 27,828 isolates from 240 participating institutions in 45 states. The results are summarized in Table 7 , which shows minimal changes over the 4 seasons reviewed.
Comment: The results in this study are not surprising when considering those reported by others. The most remarkable observation is the low rate of resistance associated with ceftriaxone and levofloxacin.
Murdoch DR. Nucleic acid amplification tests for the diagnosis of pneumonia. Clin Infect Dis. 2003;36:1162. Abstract The author provides an invited article on the molecular diagnostic techniques, primarily PCR, for rapid detection of the pathogen in patients with pneumonia. The greatest enthusiasm is for its use to detect the atypical agents: Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella. This technology can be used for detecting S pneumoniae, but it is not possible to separate colonization vs infection. For Pneumocystis carinii, there have been several reports, which are promising, but there is concern about specificity. For viruses, the author anticipates use primarily in the immunosuppressed host with pneumonia. These results are summarized in Table 8 .
Fernandez-Sabe N, Carratala J, Roson B, et al. Community-acquired pneumonia in very elderly patients: causative organisms, clinical characteristics, and outcomes. Medicine (Baltimore). 2003;82:159-169. Abstract This is an observational study from Barcelona concerning 1474 adult patients hospitalized with community-acquired pneumonia, with a specific interest in persons > 80 years of age for comparison with younger patients. Concurrent diseases that were more common in the older group included chronic lung disease, chronic heart disease, and dementia. The most common pathogen was S pneumoniae, which was recovered in 23% of both groups. A review of the 343 patients with pneumococcal pneumonia showed no important differences in presentation for those > 80 years and those younger, in terms of the frequency of sudden onset of symptoms, chills, purulent sputum, or "the classical bacterial pneumonia syndrome" (defined as 3 or more of the following: acute onset, chills, pleurisy, and purulent sputum). The observations that showed significant differences included a higher rate of aspiration pneumonia in the very elderly (10% vs 5%). The elderly showed a reduced frequency of Legionella (1% vs 8%), reduced frequency of Mycoplasma pneumoniae or Chlamydia pneumoniae (1% vs 7%), and a higher mortality rate (15% vs 6%). These data are summarized in Table 9 .
Comment: This is another of several reports on community-acquired pneumonia, but it is one of the few that addresses the issue of findings and outcome in persons over 80 years of age, sometimes referred to as "the elderly elderly." The average age in this group was 85 years, and the average in the comparison group was 60 years. It is often stated that pneumonia is more subtle in the elderly, but this did not appear to be the case, at least with the analysis of those who had pneumococcal pneumonia. There was a modest reduction in the frequency of fever at presentation (22% vs 32%).
Sisk JE, Whang W, Butler JC, Sneller VP, Whitney CG. Cost-effectiveness of vaccination against invasive pneumococcal disease among people 50 through 64 years of age: role of comorbid conditions and race. Ann Intern Med. 2003;138:960. Abstract Current guidelines recommend pneumococcal vaccine for persons ≥ 65 years and for persons at increased risk due to chronic illness including cardiovascular disease, pulmonary disease, diabetes, cirrhosis, and alcoholism. The authors, from the CDC, address the issue of cost-effectiveness of vaccination of immunocompetent persons aged 50 to 64 years, based on protection against invasive disease including bacteremia and meningitis. The results showed a cost of $2477 per quality-adjusted life-year for low-risk black people and $8195 for low-risk nonblack people. They conclude that policy makers and clinicians should consider extending routine pneumococcal vaccine to persons aged 50 to 64 years, especially for black people. They acknowledge that a major limitation in their recommendations is the lack of information on the effectiveness of revaccination, which is an important factor since risk increases with age.
Comment: There has been substantial controversy regarding Pneumovax based on multiple studies, which have failed to demonstrate benefit in preventing pneumonia or pneumococcal pneumonia.[19] More recently there have been 2 studies that suggest the benefit of Pneumovax is for the prevention of invasive pneumococcal disease.[20] Thus, the study by Sisk and associates was restricted to the cost-benefit of preventing pneumococcal bacteremia or meningitis. Several points worth emphasizing are:
The cost-effectiveness was substantially greater in black people based on prior studies that show the incidence of invasive pneumococcal disease is 2-5 times higher in this group compared with white people.[21] Not included in the analysis was a subset analysis for smokers, who have a 4-fold increase in rates of invasive pneumococcal disease.[22]
A notable limitation in the study is the fact that the duration of protection after vaccination is not known, although it is common practice to reimmunize at 5- to 10-year intervals, and the American College of International Physicians (ACIP) has recommended routine reimmunization at 75 years.
The editorial was authored by Pierce Gardner,[23] who raises the question about the possibility that early immunization may blunt the response to future vaccination, at the time when invasive disease is more likely due to age-associated risk. However, his overall impression is one of endorsing the concept of "harmonizing" influenza and pneumococcal immunizations at 50 years with possibly the highest priority for blacks, Native Americans, Alaska natives, and smokers, in addition to those who have the previously described predisposing chronic diseases.
Karlowsky JA, et al. Susceptibilities to levofloxacin in Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis clinical isolates from children: results from 2000-2001 and 2001-2002 TRUST Studies in the United States. Antimicrob Agent Chemother. 2003;47:1790. Abstract Tracking Resistance in the United States Today (TRUST) surveillance studies is a consortium of 281 clinical microbiology laboratories that provide clinical isolates for in vitro sensitivity tests under sponsorship of Ortho-McNeil Pharmaceuticals. The present report includes S pneumoniae isolates from 2834 children and 10,966 adults for 2000-2002. The results are shown in Table 10 , which provides data for persons aged 18-64 years for 2000-01 in comparison with 2001-02; also provided are results for children under age 2 years for 2001-02.
The authors conclude that 99.9% of pediatric isolates of S pneumoniae were susceptible to levofloxacin, making this "...a treatment option for pediatric patients ..."
Comment: These results make an interesting comparison with the results noted above for Canada. The author emphasizes the potential utility of fluoroquinolones in children based on the results noted in the table, which shows virtually all strains were susceptible. However, some have speculated that one of the reasons that fluoroquinolones have retained good activity against S pneumoniae is that it has not been used in children due to the contraindication for persons < 17 years. Nevertheless, there is increasing evidence of safety of these drugs in children, and it appears that they will be used in the future. The table clearly illustrates the relatively high rates of resistance in children < 2 years compared with adults, which illustrates the concern.
El-Solh AA, et al. Microbiology of severe aspiration pneumonia in institutionalized elderly. Am J Respir Crit Care Med. 2003;167:1650. Abstract This study prospectively reviews the microbiology of severe aspiration pneumonia in 95 patients of ≥ 65 years of age who were residents of long-term-care facilities admitted to the intensive care unit at the University of Buffalo Hospital. Microbiology studies included blood cultures and quantitative culture of bronchoalveolar lavage (BAL). Of the 95 patients, 54 had at least 1 microbe recovered in a concentration exceeding 103/mL. Of 67 pathogens in these 54 patients, the predominant organisms were gram-negative enteric bacilli (GNB, 49%), followed by anaerobic bacteria (16%) and S aureus (12%). Separate analysis of the group with anaerobes vs aerobes showed a similar mortality (36% vs 33%) and a similar "Plaque Index" (2.3 vs 2.2). The authors conclude that anaerobic bacteria are not common in this setting and suggest that "... adding anaerobic coverage for aspiration pneumonia in institutionalized elders needs to be re-examined."
Comment: The paper is interesting in the sense that it is a prospective study of aspiration pneumonia, something that is relatively rare, and it uses BAL as the method for microbial diagnosis. However, conclusions regarding the paucity of anaerobes is limited because: (1) there is no information about preceding antibiotics, especially at the nursing home (since this would totally negate the validity of negative anaerobic cultures); (2) it is unclear whether this laboratory has the expertise for anaerobic recovery (all prior reports of the role of anaerobes in lung disease were done by laboratories that had substantial publications to validate expertise in recovering these fastidious organisms); and (3) it is not clear that BAL is a valid method to study anaerobic lung infections (prior reports always used transthoracic needle aspirates, transtracheal aspirates, or the single report of bronchoscopy with the protected swab and quantitation). It is unfortunate that Gram stains were not reported to correlate with results, and the lack of any pathogens in the 41 culture-negative cases is unexplained, unless these were "chemical pneumonia" not requiring any antibiotics. In addition, the plaque index is not really a good indicator of any anaerobic infections since it is the gingival crevice that is important. Finally, the author makes the erroneous statement justifying the study that the Infectious Diseases Society of America (IDSA) guidelines for community-acquired pneumonia (CAP) recommend "...anaerobic coverage for patients with pneumonia with poor dentition who are at risk for aspiration or those living in a nursing home." The IDSA guidelines have not addressed the issue of "nursing home pneumonia," and my own prior recommendations have been for treatment directed against GNB and S aureus in nosocomial pneumonia, including nursing home pneumonia. Despite these criticisms, it is refreshing to see a study of pneumonia in the nursing home, since this is an area of relative neglect compared with pneumonia acquired in other settings.
Medscape Infectious Diseases. 2003;5(2) © 2003 Medscape
Cite this: July 15, 2003 - Medscape - Jul 24, 2003.
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