Community acquired pneumonia in elderly peopleBMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7146.1690 (Published 06 June 1998) Cite this as: BMJ 1998;316:1690
Current British guidelines need revision
- S J Wort, Specialist registrar,
- T R Rogers, Professor
- Deaprtment of Infectious Diseases, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN
Community acquired pneumonia is the most common reason for acute admission to hospital, with an estimated 50 000 cases occurring each year in the United Kingdom.1 Over 90% of these patients are aged over 65 years and the associated mortality is 16-40%.2 Streptococcus pneumoniae is still the most common causative organism, probably responsible for up to 40% of cases; Mycoplasma pneumoniae (3-23%), Haemophilus influenzae (5-8%), and Legionella pneumophila (3-6%) are the next commonest.2 “Atypical” pathogens are, however, becoming more prominent in old people, and current guidelines on antibiotic treatment may not be appropriate in this age group.
Until recently pneumonia due to atypical pathogens has been considered uncommon in old people: a review of 11 studies of pneumonia identified Chlamydia and Coxiella spp as the cause in only 2% of patients aged over 65.2 However, recent studies have documented Chlamydia pneumoniae in up to 26% of cases, which suggest it is the second commonest cause of pneumonia in this age group.3 Increased recognition of its role is probably due to improved methods of detection, although these are not widely available in diagnostic microbiology laboratories.
C pneumoniae was first described as a cause of pneumonia in 1985. Most infections due to this organism are believed to occur early in life and result in mild disease, although reinfection in elderly people can cause more severe disease.4 Pneumonia caused by C pneumoniae is often difficult to diagnose, with an insidious course and absence of leucocytosis.4 It seems to be a common cause of pneumonia in long term institutions,5 suggesting nosocomial transmission.
For uncomplicated pneumonia of unknown cause, of mild to moderate severity, the British Thoracic Society guidelines recommend an aminopenicillin—for example, amoxycillin or ampicillin—or benzylpenicillin.1 For severe pneumonia a second or third generation cephalosporin plus high dose erythromycin is recommended. These guidelines may not, however, be wholly appropriate in elderly people.
Firstly, the use of cephalosporins in hospital, including in elderly people, has increased greatly, although some of this may have been due to misinterpretation of the guidelines. Excessive use of these antibiotics has been implicated in the increased incidence of diarrhoea and colitis due to Clostridium difficile. 6 7 Although most antibiotics can promote Cl difficile diarrhoea, this is greater with cephalosporins.6 In addition, they are likely to select for other antibiotic resistant hospital pathogens such as vancomycin resistant enterococci. Either cefotaxime or cefuroxime has been recommended by the British Thoracic Society because of concern about penicillin resistance in S pneumoniae. However, the current rate of resistance (penicillin minimum inhibitory concentration >0.1 mg/l) for England and Wales is estimated to be only 3.8%,8 although regional variations exist. Furthermore, little evidence exists that such levels of resistance are clinically relevant in pneumococcal pneumonia providing adequate doses of penicillin are given.9 Thus there is little need to use a cephalosporin as first line treatment for community acquired pneumonia, although the local epidemiology of penicillin resistance should be considered. Amoxycillin or ampicillin remains first choice oral treatment10 with co-amoxiclav as an alternative for better activity against H influenzae; intravenous penicillin is recommended for more severe cases unless local resistance patterns preclude it, and only then should a cephalosporin be used.
Secondly, in view of the role of C pneumoniae and its resistance to β lactam antibiotics, the addition of erythromycin should always be considered unless the laboratory can rapidly exclude it. Finally, evidence is growing that newer macrolides, such as clarithromycin, are better than erythromycin in their extended antibacterial range of action and increased activity against C pneumoniae. They cause fewer gastrointestinal side effects and can be given in twice or even single daily regimens.11 Several fluoroquinolones also have a similar range of activity. Of these, sparfloxacin has been shown to be as effective as more established antibiotics, although photosensitivity was a problem.12 Clinical trials are under way to evaluate these and other new fluoroquinolones as monotherapy in community acquired pneumonia. The results may be relevant to future guidelines.