A key finding was that many patients received treatment with excessively broad-spectrum antibiotics, particularly gentamicin and cephalosporins, relative to the severity of their pneumonia as judged using the CRB-65 criteria, and the recommendations in the national guidelines. In comparison, most patients fulfilled the criteria for SIRS; according to the medical records, this was often used to justify empirical treatment. The CRB-65 criteria have been shown to be superior to SIRS for identifying patients who have pneumonia with low mortality risk, and who can thus be treated outside hospital. However, there is debate as to whether patients with low CRB-65 scores but with hypoxaemia or high levels of comorbidity should be considered for admission, and whether the CRB-65 criteria may not therefore be optimal for assessing severity and prognosis (12, 13). Other studies have compared the CRB-65 criteria with SIRS as well as the new sepsis criteria, 'quick sepsis-related organ failure assessment' (qSOFA) (14). They concluded that CRB-65 and qSOFA are better than SIRS for initial assessment of patients with pneumonia, and that CRB-65 and qSOFA are equally good for assessing severity, but that the CRB-65 criteria are better than qSOFA for predicting mortality at initial assessment (15, 16).
CRB-65 scores were not specified in any of the medical records that we reviewed. We interpret this as indicating that few were familiar with the rating system. The qSOFA criteria were not included in the national guidelines and were therefore not applied. However, it is possible that our findings with respect to empirical antibiotic treatment may have been different had the qSOFA criteria been in use in 2015, and that these criteria could in future help ensure that more patients receive empirical treatment in accordance with the recommendations in the national guidelines.
The use of gentamicin and cephalosporins should be limited for several reasons, but may be justified in cases of suspected sepsis or severe pneumonia. Gentamicin should then be given in preference to cephalosporins since gentamicin has a faster onset of bactericidal action and results in less development of resistance (17). Doctors were, however, good at discontinuing gentamicin after 1–2 doses in our patients.
For H. influenzae, resistance rates to amoxicillin and ampicillin were more than twice as high as those in the latest report from NORM (Norwegian Surveillance System for Antimicrobial Drug Resistance), and 21 (70 %) patients with H. influenzae pneumonia did not receive covering empirical treatment (5). This may indicate a need to consider adjusting the guidelines for treatment of H. influenzae based on the local pattern of resistance. On the other hand, most pneumonias caused by H. influenzae are mild and the bacterium rarely passes into the bloodstream (18). None of our patients died.
According to the CRB-65 criteria, 38 (76 %) patients who received penicillin received too high a dose. Many of them did not have their dose reduced; of those who did, the adjustment was usually carried out only upon discharge. This is consistent with the results of an intervention study by Høgli et al. (19), in which penicillin doses were reduced by 10 % without compromising treatment outcomes. The bactericidal ability of beta-lactam antibiotics depends on the length of time for which their concentration is above the minimum inhibitory concentration (MIC) and not on the peak concentration (20). To achieve sufficient bactericidal efficacy, the concentration should be above the MIC more than 50 % of the time, and penicillin should ideally be taken four times a day. Increasing the dosage of penicillin in cases of pneumonia does not usually increase bactericidal efficacy (8, 20). There should therefore be greater emphasis on selecting the correct dosage to avoid unnecessary ecological and toxic adverse effects (8).
Of the patients in our study, 62 (89 %) had their treatment changed to narrower spectrum antibiotics once the microbiological agent and its resistance status had been determined. This shows that the testing was followed up, and that efforts were made to provide treatment that was as narrow-spectrum and targeted as possible when the agent was known and the patient's clinical condition allowed. This would seem to suggest a good level of awareness and knowledge of these issues among doctors at the department.
Eight (11 %) patients stated that they had a penicillin allergy. This figure is consistent with several other studies (19, 21). However, the actual prevalence of severe penicillin allergy (type 1) is thought to be less than 0.05 % (22). We may therefore assume that our figures do not reflect reality, but this is difficult to judge as the reaction was not described adequately in the medical records. We call for greater emphasis on the overdiagnosis of penicillin allergy to avoid unnecessary use of broad-spectrum antibiotics (21, 23).
Treatment duration was not in accordance with the recommendations in the guidelines. This is consistent with the results of the intervention study by Høgli et al., in which treatment duration was successfully reduced by one day (19). However, this reduction proved to be short-lived. Høgli et al. commented that the doctors responsible for the treatment did not feel comfortable shortening the treatment course and did not appear sufficiently up-to-date regarding the latest recommendations on treatment duration. We believe that these factors may also have contributed to our finding of excessive treatment duration. Three-day treatment for mild to moderate pneumonia and five-day treatment for severe pneumonia have been shown to be non-inferior to treatment for seven to ten days in terms of clinical success rate, symptoms and mortality up to 30 days post-discharge, provided that patients show a clinical response (24, 25). In addition, short-course antibiotic treatment offers benefits in terms of reduced development of resistance, reduced costs and increased patient compliance (26). The use of new biomarkers such as procalcitonin has also been shown to help shorten pneumonia treatment by several days, but these are not yet in use by our department (27). Our findings of incomplete compliance with the guidelines in terms of risk assessment, dosage and duration of antibiotic treatment, as well as overdiagnosis of penicillin allergy, illustrate that it often takes a long time for findings from research to be implemented in clinical practice, and that there is a need for greater focus on adopting the latest evidence-based practices to ensure that patients receive the best possible treatment (28).