Guideline for Antibiotic Use in Adults with Community-acquired Pneumonia.

Community-acquired pneumonia is common and important infectious disease in adults. This work represents an update to 2009 treatment guideline for community-acquired pneumonia in Korea. The present clinical practice guideline provides revised recommendations on the appropriate diagnosis, treatment, and prevention of community-acquired pneumonia in adults aged 19 years or older, taking into account the current situation regarding community-acquired pneumonia in Korea. This guideline may help reduce the difference in the level of treatment between medical institutions and medical staff, and enable efficient treatment. It may also reduce antibiotic resistance by preventing antibiotic misuse against acute lower respiratory tract infection in Korea.

Introduction

1. Background of guidelines

Clinical practice guidelines based on evidence-based medicine promote evidence-based, objective, and efficient medical practices. Numerous evidence-based clinical practice guidelines have also been developed, including the treatment guideline for community-acquired pneumonia developed in 2009. Additional data about the distribution of the causative bacteria of community-acquired pneumonia and antibiotic resistance have been obtained since then, and various guidelines about the diagnosis, treatment, and prevention of pneumonia have also been developed abroad. It has therefore become necessary to revise the current guideline on community-acquired pneumonia in Korea.

Antibiotic resistance has recently been raised as a serious public health issue worldwide. This is because whereas resistant bacteria that cannot be removed with existing antibiotics are increasing in number, less and less novel antibiotics are being developed. The issue of antibiotic resistance is much more serious in Korea than in other countries, with major causative bacteria having the highest antibiotic resistance in the former worldwide. Antibiotic resistance is proportional to the level of antibiotic misuse. The level of antibiotic use in Korea is higher than the average level of antibiotic use worldwide. The rate of prescribing antibiotics for infections that do not require antibiotic treatment is also higher in Korea than in other countries.

The present clinical practice guideline provides revised recommendations on the appropriate diagnosis, treatment, and prevention of community-acquired pneumonia. This guideline may help reduce the difference in the level of treatment between medical institutions and medical staff, and enable efficient treatment. It may also reduce antibiotic resistance by preventing antibiotic misuse against acute lower respiratory tract infection in Korea.

2. Development process of diagnosis and treatment guidelines

1) Guideline development committee

An antibiotic treatment guideline development committee for lower respiratory tract infection in adults was formed in November 2016. The committee included as many associated medical institutions as possible.

Committee members recommended by the Korean Society for Chemotherapy, the Korean Society of Infectious Diseases, the Korea Academy of Tuberculosis and Respiratory Diseases, the Korean Association of Family Medicine, the Korean Medical Practitioners Association, and the National Evidence-based Healthcare Collaborating Agency participated in the development of this guideline.

2) Guideline target and scope

This guideline sets forth fundamental principles of antibiotic use against community-acquired pneumonia in adults aged 19 years or older, taking into account the current situation regarding community-acquired pneumonia in Korea as of March 2017.

3) Method of literature search

Studies published in English in the last 10 years were searched. OVID-MEDLINE and OVID-EMBASE were used to search for foreign studies, and KMBase and KoreaMed were used to search domestic studies. Clinical practice guidelines were searched on NGC, G-I-N, and KoMGI. The search date is February 10th, 2017.

4) Recommendation and evidence levels

The level of recommendation was divided into “Strong, Weak”, and the level of evidence was divided into “High, Moderate, Low, Very low”. The level of recommendation and the level of evidence were determined using an unofficially agreed method. A consensus was deemed reached if over 70% of the participating committee members agreed.

(1) Level of recommendation

① Strong: Benefits evidently outweigh costs or loss, or costs and loss evidently outweigh benefits.

② Weak: Level of evidence is low, or there is no clear difference between benefits and loss.

(2) Level of evidence

① High: The possibility that the level of certainty about the estimated value of an effect will change in future studies is very low.

② Moderate: Future studies will have an important influence on the level of certainty about the estimated value of an effect, and the value may change.

③ Low: Future studies are highly likely to affect the level of certainty about the estimated value of an effect, and the value is highly likely to change.

④ Very low: An effect cannot be estimated with certainty.

5) Guideline developmental process

This clinical practice guideline was developed using the adaptation method. First, 22 key questions (KQ) to be included in the guideline were selected. The key questions followed the population intervention, comparison, and outcome (PICO) principle. During the literature search process, experts used systematic search equations to search a total of 1,699 studies based on their contents. Experts reviewed the titles and abstracts of studies whose original copies were available, and selected 17 studies. Of these, a total of four clinical practice guidelines that addressed the key questions to be included in this guideline extensively were selected.

The qualities of these four domestic and foreign clinical practice guidelines were assessed using an assessment scale developed by the Clinical Practice Guideline Expert Committee of the Korean Academy of Medical Sciences, namely, the K-AGREE 2.0 (Korean version of AGREE 2.0). Twelve committee members who were educated on the assessment method through a workshop run by experts assessed the selected studies. Two guidelines which the British Thoracic Society (BTS) guidelines for the management of community acquired pneumonia in adults (updated in 2009) and the guidelinea for the management of adult lower respiratory tract infections (updated in 2011) by the Joint Taskforce of the European Respiratory Society and European Society for Clinical Microbiology and Infectious Diseases were selected for review. Ultimately a total of four clinical practice guidelines including a domestic guideline published in 2009 and a consensus guideline on the management of community-acquired pneumonia in adults published by the Infectious Diseases Society of America/American Thoracic Society (IDSA/ATS) in 2007, which were the adaptation targets for domestic guidelines, were selected as adaptation targets.

The guideline developed by the Guideline Development Committee through internal meetings was presented in the spring academic conferences held by the Korean Society for Chemotherapy and the Korean Society of Infectious Diseases in 2017. The guideline was revised and improved based on what was discussed at the conferences. Further revisions were made based on expert opinions gathered during a public hearing participated in by experts from each related association to complete the guideline development.

6) Limitations and future to do’s

This guideline has been developed using the adaptation method due to time limitations. Although some of the foreign clinical practice guidelines from which this guideline was adapted were scheduled for revisions in the near future, they were not presented during the developmental period, and could not be used in the development of this guideline. This guideline will undergo minor revisions as soon as the revised versions of these guidelines are published. This guideline will also be revised every 4-5 years to reflect recent study results both outside and inside Korea.

7) Support

This guideline has been developed with funds from the Government’s Policy Research Projects of the Disease Control Centre in 2016. The committee members who participated in the guideline development were not influenced by any government branches, academic societies, pharmaceutical companies, or interest groups.

Summary of guidelines on antibiotic use for community-acquired pneumonia

Guideline for Antibiotic Use in Adults with Community-acquired Pneumonia

Current status regarding causative bacteria of pneumonia

1. Causative bacteria of community-acquired pneumonia

Most antibiotic treatments for pneumonia depend on the empirical method. Since the distribution of causative bacteria and antibiotic resistance vary between countries, it is necessary to develop an appropriate antibiotic treatment guideline based on domestic epidemiological data [12]. This guideline summarizes domestic research findings on the causative bacteria of community-acquired pneumonia affecting Korean adults, and the current level of antibiotic resistance in Korea.

Community-acquired pneumonia is caused by various bacteria. Similar distributions of these bacteria are seen between Korea and other countries. Bacteria such as Streptococcus pneumoniae, and Haemophilus influenzae, and Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila, which are classified as causative bacteria of atypical pneumonia, and respiratory bacteria can cause pneumonia. However, it is difficult to differentiate between these causative bacteria in the early period after hospital admission. Study findings about the major causative bacteria of community-acquired pneumonia in Korea are summarized in Table 1. The most important causative bacteria of bacterial pneumonia are S. pneumoniae. They account for 27-69% of all causative bacteria of bacterial pneumonia [345678910]. Haemophilus or Moraxella, which are respiratory pathogens, commonly cause pneumonia in patients with a lung disease. The prevalence of these bacteria varies greatly in domestic data possibly because the separation and identification of these bacteria are difficult. Staphylococcus aureus are also relatively common causative bacteria. They commonly occur after an influenza epidemic. Enteric Gram negative bacilli or Pseudomonas aeruginosa pneumonia commonly occur in patients who have underlying lung diseases, who have alcohol addiction, or who have frequently undergone antibiotic treatment. Domestic data show the ratio of Gram-negative bacteria including Klebsiella pneumoniae and P. aeruginosa to be relatively high. This may be because most domestic studies have been conducted in tertiary university hospitals, and therefore, a large number of patients who are frequently admitted to a hospital for chronic respiratory diseases were included. Studies have reported mixed infections caused by two or more microorganisms to be relatively common. These infections include mixed infections caused by atypical causative bacteria of pneumonia. Distributions of causative bacteria may change depending on underlying diseases and risk factors.

Table 1

The distribution of the major causative bacteria of community-acquired pneumonia in Korean adults

		Jeong et al [7]	Seong et al [4]	Chong et al [10]	Choi et al [9]	Yoo et al [3]	Kim et al [5]	Kang et al [6]	Jeon et al [8]
No. of patients		519	275	619	2,221	693	456	212	175
No. of causative bacteria isolated		122	105	131	568	191	250	62	63
Gram-positive bacteria
	Streptococcus pneumoniae	59 (48.4)	44 (41.9)	52 (39.7)	276 (48.6)	51 (26.7)	88 (35.2)	43 (69.4)	21 (33.3)
	Staphylococcus aureus	13 (10.7)	10 (9.5)	8 (6.1)	109 (19.2)	21 (11.0)	5 (2.0)	8 (12.9)	9 (14.3)
	Streptococcus species	8 (6.6)	5 (4.8)	1 (0.8)	9 (1.6)	5 (2.6)	5 (2.0)	-	-
Gram-negative bacteria
	Klebsiella pneumoniae	14 (11.5)	6 (5.7)	26 (19.8)	105 (18.5)	17 (8.9)	7 (2.8)	3 (4.8)	13 (20.6)
	Pseudomonas aeruginosa	11 (9.0)	10 (9.5)	11 (8.4)	83 (14.6)	22 (11.5)	2 (0.8)	2 (3.2)	4 (6.3)
	Hemophilus influenzae	7 (5.7)	1 (1.0)	1 (0.8)	105 (18.5)	10 (5.2)	5 (2.0)	7 (11.3)	7 (11.1)

Data are shown in percentage (%).

M. pneumoniae, C. pneumoniae, and L. pneumophila are the major causative bacteria of atypical pneumonia. Of the recently published studies on community-acquired pneumonia in Korea, very few have investigated the incidence of atypical pneumonia and its causative bacteria. A large number of published studies have been conducted at a single institution, or use a retrospective design. Therefore, the prevalence of atypical pneumonia in Korea and clinical significance can only be assessed with limited accuracy. In a domestic study on pneumonia, Mycoplasma, C. pneumoniae, and Legionella accounted for 6.3-9.2%, 7.1-13.2%, and 0.5-3% of all cases of pneumonia [111213]. Legionella were especially more common for cases of moderate to severe pneumonia requiring ICU admission compared with other atypical pneumococcal bacteria.

Respiratory virus induces pneumonia in children, as well as community-acquired pneumonia in adults. Rapid antigen tests for influenzas and respiratory syncytial virus (RSV) have recently been introduced and used in clinical settings. Multiplex reverse transcriptase polymerase chain reaction (RT-PCR) has also been used against various respiratory viruses. In a recent study involving 456 adults with community-acquired pneumonia, multiplex RT-PCR was performed for 327 patients. Respiratory viruses were detected in 60 patients (18.3%) [5]. Influenza virus was the most common (n = 23, 38%), followed by RSV (n = 9, 15%), rhinovirus (n = 7, 12%), coronavirus (n = 6, 10%), adenovirus (n = 6, 10%), metapneumovirus (n = 5, 8%), parainfluenza virus (n = 3, 5%) [6]. When a respiratory virus test was performed on patients with community-acquired pneumonia hospitalized in ICU, more than one type of respiratory virus was detected in 72 of 198 patients (36.4%) for whom RT-PCR was performed [14]. Rhinovirus was the most common (n = 17, 23.6%), followed by parainfluenza (n = 15, 20.8%), metapneumovirus (n = 13, 18.1%), influenza virus (n = 12, 16.7%), RSV (n = 10, 13.9%), coronavirus (n = 4. 5.6%), and adenovirus (n = 1, 1.4%) [14]. Other causative bacteria of atypical pneumonia in Korea include Mycobacterium tuberculosis, non-tuberculous mycobacteria, Orientia tsutsugamushi, Leptospira, Coxiella burnetii. Since the prevalence of tuberculosis is still quite high, the possibility of tuberculosis being one of the causes of pneumonia must always be considered. When a patient shows delayed response to antibiotic treatment, or has underlying diseases such as diabetes, chronic obstructive respiratory disease, chronic kidney diseases, and long-term steroid use, tuberculosis must be considered as a possible cause of pneumonia. In addition, pneumonia caused by M. tuberculosis can occur as typical bacterial pneumonia or atypical pneumonia. Since tsutsugamushi disease and leptospirosis, which are febrile illnesses that usually occur in the fall, are sometimes accompanied by atypical pneumonia, when a patient has a febrile illness accompanied by pneumonia in the fall, pneumonia must be differentiated with the possibility of febrile illnesses in mind. Furthermore, as there have been reports of pneumonia caused by C. burnetii in Korea, it is necessary to differentiate C. burnetii, which may possibly be the causative bacteria of pneumonia in persons who come in close direct or indirect contact with livestock. Table 2 lists common causative bacteria of community-acquired pneumonia by epidemiological characteristics and risk factors [15]. Table 3 summarizes common clinical characteristics associated with certain causative bacteria [16].

Table 2

Common causative bacteria of community-acquired pneumonia by epidemiological characteristics and risk factors

Risk factors and epidemiological characteristics	Common causative bacteria
Alcohol addiction	Streptococcus pneumoniae, oral anaerobes, Klebsiella pneumoniae, Acinetobacter species, Mycobacterium tuberculosis
Chronic obstructive pulmonary disease, smoking	Haemophilus influenzae, Pseudomonas aeruginosa, Legionella species, S. pneumoniae, Moraxella catarrhalis, Chlamydophila pneumonia
Smoking	Gram-negative enteric pathogens, oral anaerobes
Lung abscess	Oral anaerobes, M. tuberculosis, atypical mycobacteria
Exposure to birds	Chlamydophila psittaci (if poultry: avian influenza)
Exposure to farm animals	Coxiella burnetii (Q fever)
Influenza epidemic	Influenza virus, S. pneumoniae, Staphylococcus aureus, H. influenza
Long-term coughing or vomiting after coughing	Bordetella pertussis
Structural anomalies of the lung (e.g. bronchodilation)	Pseudomonas aeruginosa, Burkholderia cepacia, Staphylococcus aureus
Use of intravenous medications	S. aureus, anaerobes, M. tuberculosis, S. pneumonia
Bronchial obstruction	Anaerobes, S. pneumoniae, H. influenzae, S. aureus

Table 3

Common clinical characteristics associated with specific causative bacteria

Causative bacteria	Common clinical characteristics
Streptococcus pneumoniae	Age, underlying diseases, acute progress, fever, pleuritic chest pain
Bacteremic S. pneumoniae	Female gender, alcohol addiction, diabetes, chronic obstructive pulmonary disease, dry cough
Legionella pneumophila	Relatively young female, smoker, having no underlying diseases, diarrhea, neurological symptoms, severe pneumonia, multiple organ dysfunctions (e.g. liver dysfunction, kidney dysfunction, etc.)
Mycoplasma pneumoniae	Young age, previous history of antibiotic use, multiple organ dysfunction is uncommon
Chlamydophila pneumoniae	Symptoms that persisted for a long period before hospital admission, headache

2. Antibiotic resistance of the major causative bacteria of community-acquired pneumonia in Korea

S. pneumoniae isolated in Korea have been reported to be highly resistant against penicillin. In an investigation on antibacterial resistance measured according to the antimicrobial susceptibility testing standards, S. pneumoniae were moderately or highly resistant to penicillin [17]. However, as experts claimed that there is no association between clinical outcomes of pneumonia caused by penicillin-resistant S. pneumoniae and antibiotic resistance against penicillin, the antimicrobial susceptibility testing standards by the Clinical and Laboratory Standards Institute (CLSI) of the United States were revised in January 2008. According to the previous standards, S. pneumoniae are deemed to be susceptible to penicillin if MIC ≤0.06 μg/mL, moderately resistant if MIC=0.1-1.0 μg/mL, and highly resistant if MIC ≥2.0 μg/mL. The revised standards deem the bacteria to be susceptible if MIC ≤2.0 μg/mL, moderately resistant if MIC=4.0 μg/mL, and highly resistant if MIC ≥8.0 μg/mL. When the revised standards are used, the antibacterial resistance against pencilling drops to below 10%. Table 4 summarizes the current antibiotic resistance of S. pneumoniae strains isolated in Korea. While then antibiotic resistance against penicillin and ceftriaxone is reported to be low at 10% or below, that against erythromycin and azithromycin are still high at 73-81% [1819202122]. Antibiotic resistance against fluoroquinolones is still quite low, but gradually increasing. Antibiotic resistance against levofloxacin and moxifloxacin is reported at 0.8-8.2%, and 0.9-1.0%, respectively [1820].

Resistance against ampicillin due β-lactamase production is common in H. influenzae. In a domestic study that analysed 544 bacterial strains, the antibiotic resistance against ampicillin, cefuroxime, clarithromycin, cefaclor, and amoxicillin/clavulanate was 58.5%, 23.3%, 18.7%, 17.0%, and 10.4%, respectively [23]. This study did not identify bacterial strains that are resistant to levofloxacin and cefotaxime. In another study that analysed 229 bacterial strains, the antibiotic resistance against ampicillin high at 58.1%, and that against cefaclor, clarithromycin, amoxicillin/clavulanate, cefixime, and levofloxacin was 41.4%, 25.8%, 13.5%, 10.9%, and 1.3%, respectively [24].

Not many studies have analysed the antibiotic susceptibility of M. pneumoniae in Korea. In a study that examined M. pneumoniae isolated from respiratory organ samples of pediatric patients in 2000-2011, genes related to macrolide resistance was detected in 31.4% of the samples, and this rate was reported to increase every year [25]. In another study using respiratory organ samples from pediatric patients, genes related to macrolide resistance were found in 17.6% of the samples of M. pneumoniae [26]. Although the ratio of methicillin-resistant S. aureus (MRSA) in community-acquired S. aureus infection has been increasing in Korea, systematic research on the role of MRSA in community-acquired pneumonia is lacking [272829].

New method of diagnosing pneumonia

1. Respiratory virus PCR

Methods of respiratory virus testing include the culture test, rapid antigen test, immunofluorescence, enzyme immunoassay test, and PCR. PCR is more sensitive than the culture test, or the enzyme immunoassay test [30]. This strength of PCR makes it advantageous for adult patients with a smaller number of nasopharyngeal virus compared with pediatric patients [3132]. Multiplex RT-PCR is useful for simultaneously testing various respiratory viruses, and is frequently used today [33].

PCR can test various respiratory organ samples including nasopharyngeal samples, sputum, airway aspirates, and bronchoalveolar lavage fluid [3132]. In most studies on pneumonia caused by respiratory viruses, virus testing was performed using samples from the upper airway. Nasal swabs are the most commonly used method to detect viruses, and are more sensitive than throat swabs in adults [31].

In 20-40% of patients with community-acquired pneumonia, respiratory viruses are detected by PCR [34353637]. Rhinovirus is the most commonly detected, and other respiratory viruses such as influenza, metapneumovirus, RSV, parainfluenza virus, and coronavirus are also relatively commonly detected [3839].

However, positive results of upper airway samples do not necessarily indicate viral infection, and positive PCR results do not indicate that pneumonia was caused by a respiratory virus. Furthermore, although respiratory viruses can induce pneumonia by themselves, they may simple be a predisposing factor of pneumonia [40]. Therefore, the possibility of bacterial pneumonia cannot be disregarded simply because respiratory bacteria were detected in the PCR test. In fact, respiratory viruses are detected in 20% of patients diagnosed with bacterial pneumonia [40].

It is unclear whether the use of antiviral agents is necessary or not when respiratory viruses aside from influenza are detected, and it is difficult to diagnose viral pneumonia based on positive results only [33]. With the costs of tests and various factors taken into consideration [33], it may be useful to perform the PCR test to detect respiratory viruses when a patient is suspected of having pneumonia caused by respiratory viruses based on clinical symptoms or radiographic findings.

2. Legionella, Mycoplasma, Chlamydophila PCR

1) Legionella PCR

Whereas the Legionella urinary antigen test can only diagnose the L. pneumophila serogroup 1, PCR can diagnose all serogroups, and thus has higher sensitivity for Legionella diagnosis. In a recent systematic review, the sensitivity of the Legionella PCR test using respiratory organ samples was 97.4%, and its specificity was 98.6% [41]. Legionella PCR may be performed using nasopharyngeal samples or nasal swabs when no sputum is secreted even in the induced sputum analysis, but this testing method has a lower diagnosis rate compared with when sputum samples are used [4243].

2) Mycoplasma PCR

Various serological tests have been traditionally used to diagnose Mycoplasma. These tests may fail to detect antibodies in the early period after infection [4445], and IgM antibody reactions may not occur in adults aged 40 years or older [46]. Mycoplasma PCR, which uses various respiratory organ samples has higher sensitivity, has higher sensitivity than serological tests [47], and has similar sensitivity to that of Legionella PCR [48]. Just as Legionella PCR, Mycoplasma PCR has a lower diagnosis rate with nasopharyngeal samples than with sputum samples [49].

3) Chlamydophila PCR

Serological tests for Chlmydophila have lower specificity compared with PCR [50], and may report false negative in the early period after infection as is the case with Mycoplasma infection [51]. For this reason, PCR may be more useful than serological tests for diagnosing Chlmydophila infection. Although the sensitivity of Chlamydophila PCR has not been accurately measured, Chlamydophila PCR is reported to have high specificity [52].

3. Chest CT

Chest computed tomography (CT) is the most accurate test for assessing parenchymal anomalies. Radiographic findings indicative of pneumonia may be observed even when no anomalies are observed on chest X-rays [53]. Chest CT is more accurate than chest X-rays in the diagnosis of complications such as pleuritis and pulmonary necrosis [5455] and in the exclusive diagnosis and differential diagnosis of non-infectious lung diseases such as atelectasis, pulmonary infarction, tumor, and interstitial lung disease that may exhibit similar characteristics as those of pneumonia on X-rays [56575859]. Since CT findings can vary depending on the identity of the causative bacteria of pneumonia, CT is useful for identifying causative bacteria [56606162]. CT findings suggestive of mycobacteria that must be differentiated from common pneumonia, and of fungal lung infection can also be obtained [566364].

However, due to the relatively high cost and danger of irradiation compared with those of chest X-rays [65], CT must be selectively performed in cases where the differentiation of accompanying diseases such as pulmonary embolism is necessary, fungal infection is suspected, it is difficult to check for lung infiltration on chest X-rays due to other underlying lung diseases, and it is difficult to check for pneumonia complications due to lack of response to pneumonia treatment [33].

4. Chest ultrasounds

Chest ultrasounds are used in the diagnosis of various lung diseases such as pneumothorax, hydrothorax, and pulmonary enema, as well as pneumonia [66]. According to a recent systematic review and meta-analysis using the data of 1,172 patients diagnosed with pneumonia, chest ultrasounds had excellent sensitivity and specificity of 94% and 96%, respectively, in the diagnosis of pneumonia [67].

Compared to chest X-rays, chest ultrasounds do not pose the burden of radiation exposure, can be performed right next to the patient, can be performed on pregnant women, and can more accurately diagnose lung consolidation and hydrothorax [666768]. It is also useful for evaluating hydrothorax, which can occur as a complication of pneumonia. It can diagnose septation within hydrothorax more accurately than CT [69]. Septation is indicative of birous strands between the parietal and visceral pleura, as well as inefficient drainage through the drainage tube [56].

A trained examiner must perform ultrasounds to obtain accurate results. Although a problem of interexaminer reproducibility may arise [70], chest ultrasounds may be useful for diagnosing and assessing pneumonia in situations where it is impossible to take chest X-rays (i.e. it is difficult to transfer a patient to the examination room because the patient is pregnant or immobile).

Diagnosis of pneumonia

KQ 1. For adults who may have contracted community-acquired pneumonia, are the tests used to identify causative helpful for selecting therapeutic antibiotics?

Recommendation

Use an appropriate testing method to identify the causative bacteria of pneumonia when a patient is diagnosed with moderate or severe community-acquired pneumonia (level of recommendation: strong, level of evidence: low).

Selectively perform tests according to age, underlying diseases, severity markers, epidemiological factors, and current history of antibiotic use when treating outpatients with community-acquired pneumonia of low severity (level of recommendation: strong, level of evidence: low).

It is advisable to perform blood culture, and sputum Gram smear and culture tests before antibiotic administration for patients with community-acquired pneumonia who require hospitalization (level of recommendation: strong, level of evidence: low).

Key points

Although microbial tests have low sensitivity for community-acquired pneumonia, they are still required for reasons related to appropriate antibiotic use, public health and epidemiological importance, and provision of information about causative bacteria within communities.

For outpatients who are suspected of having antibiotic-resistant bacteria or bacteria that are difficult to treat empirically using common antibiotics, perform sputum gram smear and culture.

For all inpatients with pneumonia, it is recommended to perform blood culture, and sputum gram smear and culture tests before antibiotic treatment as long as they are clinically indicated.