***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND Therapy with antibiotics influences recovery only in selected cases of COPD exacerbations . We evaluated the efficacy and safety of procalcitonin guidance compared to st and ard therapy with antibiotic prescriptions in patients experiencing exacerbations of COPD . METHODS A total of 208 consecutive patients requiring hospitalization for COPD exacerbation were r and omized at the index exacerbation to procalcitonin-guided or st and ard antibiotic therapy . Patients receiving procalcitonin-guided therapy were treated with antibiotics according to serum procalcitonin levels ; st and ard-therapy patients received antibiotics according to the attending physician . The primary outcome was the antibiotic exposure at the index exacerbation and the subsequent antibiotic requirement for COPD exacerbation within 6 months . Secondary outcomes were clinical recovery , symptom scores , length of hospitalization , ICU stay , death , lung function , exacerbation rate , and time to next exacerbation . RESULTS At the index exacerbation , procalcitonin guidance reduced antibiotic prescription ( 40 % vs 72 % , respectively ; p < 0.0001 ) and antibiotic exposure ( relative risk [ RR ] , 0.56 ; 95 % confidence interval [ CI ] , 0.43 to 0.73 ; p < 0.0001 ) compared to st and ard therapy . Moreover , procalcitonin guidance at the index exacerbation allowed a significant sustained reduction in total antibiotic exposure for up to 6 months ( RR , 0.76 ; 95 % CI , 0.64 to 0.92 ; p = 0.004 ) . Clinical outcome and improvement in FEV(1 ) at 14 days and 6 months did not differ between groups . Within 6 months , the exacerbation rate ( 0.62 vs 0.64 , respectively ) , the rehospitalization rate ( 0.21 vs 0.24 , respectively ) , and mean ( + /- SD ) time to the next exacerbation ( 70.0 + /- 46.1 vs 70.4 + /- 51.9 days , respectively ; p = 0.523 ) were similar in both groups . CONCLUSIONS Procalcitonin guidance for exacerbations of COPD offers a sustained advantage over st and ard therapy in reducing antibiotic use for up to 6 months with a number-needed-to-treat of 3 BACKGROUND Reduced duration of antibiotic treatment might contain the emergence of multidrug-resistant bacteria in intensive care units . We aim ed to establish the effectiveness of an algorithm based on the biomarker procalcitonin to reduce antibiotic exposure in this setting . METHODS In this multicentre , prospect i ve , parallel-group , open-label trial , we used an independent , computer-generated r and omisation sequence to r and omly assign patients in a 1:1 ratio to procalcitonin ( n=311 patients ) or control ( n=319 ) groups ; investigators were masked to assignment before , but not after , r and omisation . For the procalcitonin group , antibiotics were started or stopped based on predefined cut-off ranges of procalcitonin concentrations ; the control group received antibiotics according to present guidelines . Drug selection and the final decision to start or stop antibiotics were at the discretion of the physician . Patients were expected to stay in the intensive care unit for more than 3 days , had suspected bacterial infections , and were aged 18 years or older . Primary endpoints were mortality at days 28 and 60 ( non-inferiority analysis ) , and number of days without antibiotics by day 28 ( superiority analysis ) . Analyses were by intention to treat . The margin of non-inferiority was 10 % . This trial is registered with Clinical Trials.gov , number NCT00472667 . FINDINGS Nine patients were excluded from the study ; 307 patients in the procalcitonin group and 314 in the control group were included in analyses .  Mortality of patients in the procalcitonin group seemed to be non-inferior to those in the control group at day 28 ( 21.2 % [ 65/307 ] vs 20.4 % [ 64/314 ] ; absolute difference 0.8 % , 90 % CI -4.6 to 6.2 ) and day 60 ( 30.0 % [ 92/307 ] vs 26.1 % [ 82/314 ] ; 3.8 % , -2.1 to 9.7 ) . Patients in the procalcitonin group had significantly more days without antibiotics than did those in the control group ( 14.3 days [ SD 9.1 ] vs 11.6 days [ SD 8.2 ] ; absolute difference 2.7 days , 95 % CI 1.4 to 4.1 , p<0.0001 ) . INTERPRETATION A procalcitonin-guided strategy to treat suspected bacterial infections in non-surgical patients in intensive care units could reduce antibiotic exposure and selective pressure with no apparent adverse outcomes . FUNDING Assistance Publique-Hôpitaux de Paris , France , and Brahms , Germany Can procalcitonin testing reduce antibiotic prescribing for respiratory infections ? SIR — Christ-Crain and colleagues have recently reported that procalcitonin ( PCT ) testing can reduce significantly antibiotic prescribing ( from 83 % in the control group down to 44 % with PCT-guided treatment ) in patients admitted with a lower respiratory tract infection ( LRTI ) [ 1 ] . Clearly , achieving such a large reduction in antibiotic prescribing , and with no deleterious effect on clinical outcomes as in this study , would be extremely desirable in all health care setting s. In the UK , both methicillin-resistant Staphylococcus aureus ( MRSA ) and Clostridium difficile are important nosocomial infections , which recently have attracted much attention by both the media and the Department of Health . Antibiotic usage in hospitals has been shown to be a risk factor for both C. difficile [ 2 ] and MRSA [ 3 , 4 ] , as well as for antibiotic resistance in other bacterial species . Because of the common risk factors , the same preventative strategies , including control of antibiotic usage , can reduce both MRSA and C. difficile [ 5 ] . Recently , there have been reports of both increasing numbers of C. difficile and an increasing case-fatality ratio [ 6 , 7 ] . Inflammatory markers may help to identify patients who require antibiotics , and PCT may be preferable to C-reactive protein ( CRP ) testing . The main advantage of PCT is its faster response to inflammatory insults such as bacterial sepsis : as a result , PCT is both more sensitive and more specific than CRP in the diagnosis of bacterial infection [ 8 ] . We decided to conduct an assessment of whether the excellent results by Christ-Crain could be obtained in routine use , that is , outside the r and omised trial setting s typically associated with high level of enthusiasm and commitment . As our assessment was not a r and omised trial , we primarily aim ed at auditing the proportion of patients receiving antibiotics despite a low PCT test result , using as st and ard the low antibiotic usage ( 10.4 % ) achieved by Christ-Crain et al. [ 1 ] for this category of patients in their r and omised trial . Methods The Microbiology Department took a Kryptor analyser on a temporary loan for over a period of 2 months ( February and March 2005 ) and conducted 188 tests for care of the elderly patients ( aged 70 years and above ) and 31 for chest medicine patients . Before the testing started , a protocol had been distributed and meetings had been arranged with the physicians in these two units . All physicians in these two units were encouraged to utilise the PCT result , as well as PURPOSE The aim of this study was to determine the safety of targeted antibiotic therapy ( TT ) in ventilator-associated pneumonia ( VAP ) . MATERIAL S AND METHODS This was a secondary analysis from a multicenter trial of 740 patients with suspected VAP r and omized to bronchoscopy or endotracheal aspirate cultures ; all received empirical broad-spectrum antibiotics .  Patients were grouped by whether they received TT , defined as tailoring or discontinuing antibiotics in response to enrolment culture results . RESULTS For patients with a positive culture ( n = 412 ) , baseline demographics , clinical progression of infection and multiple organ dysfunction scores ( MODS ) , and mortality were similar for those on TT ( n = 320 ) or those who did not receive TT ( NoTT ) ( n = 92 ) . The TT group had more days alive and off broad-spectrum antibiotics ( 14.5 vs 13.2 , P = .04 ) . In patients with a negative culture ( n = 327 ) , those on TT ( n = 230 ) had similar baseline demographics , less frequent final adjudicated diagnosis of VAP ( 63.0 % vs 76.3 % , P = .02 ) , and less severe clinical progression of infection and MODS compared with NoTT ( n = 97 ) . The TT group had more days alive and off broad-spectrum antibiotics ( 15.9 vs 13.1 , P < .001 ) , lower delta MODS ( 2.0 vs 3.0 , P = .01 ) , fewer mechanical ventilation days ( 9.8 vs 14.7 , P = .03 ) , and similar mortality compared to NoTT . CONCLUSIONS Targeted therapy is associated with less antibiotic use and no evidence of harm in the management of patients with VAP RATIONALE In patients with community-acquired pneumonia , guidelines recommend antibiotic treatment for 7 to 21 d. Procalcitonin is elevated in bacterial infections , and its dynamics have prognostic implication s. OBJECTIVE To assess procalcitonin guidance for the initiation and duration of antibiotic therapy in community-acquired pneumonia . METHODS In a r and omized intervention trial , 302 consecutive patients with suspected community-acquired pneumonia were included . Data were assessed at baseline , after 4 , 6 , and 8 d , and after 6 wk . The control group ( n = 151 ) received antibiotics according to usual practice . In the procalcitonin group ( n = 151 ) , antibiotic treatment was based on serum procalcitonin concentrations as follows : strongly discouraged , less than 0.1 microg/L ; discouraged , less than 0.25 microg/L ; encouraged , greater than 0.25 microg/L ; strongly encouraged , greater than 0.5 microg/L. The primary endpoint was antibiotic use ; secondary endpoints were measures of clinical , laboratory , and radiographic outcome . RESULTS At baseline , both groups were similar regarding clinical , laboratory , and microbiology characteristics , and Pneumonia Severity Index .  Procalcitonin guidance reduced total antibiotic exposure ( relative risk , 0.52 ; 95 % confidence interval , 0.48 - 0.55 ; p < 0.001 ) , antibiotic prescriptions on admission ( 85 vs. 99 % ; p < 0.001 ) , and antibiotic treatment duration ( median , 5 vs. 12 d ; p < 0.001 ) compared with patients treated according to guidelines . After adjustment for Pneumonia Severity Index , the hazard ratio of antibiotic discontinuation was higher in the procalcitonin group than in the control group ( 3.2 ; 95 % confidence interval , 2.5 to 4.2 ) . Outcome was similar in both groups , with an overall success rate of 83 % . CONCLUSIONS Procalcitonin guidance substantially reduces antibiotic use in community-acquired pneumonia . These findings may have important clinical and public health implication Recent studies have suggested that procalcitonin ( PCT ) is a safe marker for the discrimination between bacterial and viral infection , and that PCT-guided treatment may lead to substantial reductions in antibiotic use . The present objective was to evaluate the effect of a single PCT measurement on  antibiotic use in suspected lower respiratory tract infections ( LRTIs ) in a Danish hospital setting . In a r and omized , controlled intervention study , 223 adult patients admitted to the hospital because of suspicion of LRTI were included with 210 patients available for analysis . Patients were r and omized to either PCT-guided treatment or st and ard treatment . Antibiotic treatment duration in the PCT group was based on the serum PCT value at admission . The cut-off point for recommending antibiotic treatment was PCT > or = 0.25 microg/L. Physicians could overrule treatment guidelines . The mean duration of hospital stay was 5.9 days in the PCT group vs. 6.7 days in the control group ( p 0.22 ) . The mean duration of antibiotic treatment during hospitalization in the PCT group was 5.1 days on average , as compared to 6.8 days in the control group ( p 0.007 ) . In a subgroup analysis of chronic obstructive pulmonary disease patients , the mean length of stay was reduced from 7.1 days in the control group to 4.8 days in the PCT group ( p 0.009 ) . It was concluded that the determination of a single PCT value at admission in patients with suspected LRTIs can lead to a reduction 
    Output:
    
Procalcitonin-guided antibiotic therapy is associated with a reduction in antibiotic usage that , under certain assumptions , may reduce overall costs of care .