Efficacy and safety of isavuconazole against deep-seated mycoses: A phase 3, randomized, open-label study in Japan.

OBJECTIVES: Isavuconazole is a convenient triazole antifungal agent with a broad antifungal spectrum. A randomized, open-label study (ClinicalTrials.gov, NCT03471988) was conducted to evaluate the efficacy and safety of isavuconazole in Japanese patients with deep-seated mycoses. PATIENTS AND METHODS: In Cohort A, patients with aspergillosis (chronic pulmonary aspergillosis and invasive aspergillosis) were randomized in a 2:1 ratio to isavuconazole or voriconazole, and in Cohort B, patients with cryptococcosis and mucormycosis were assigned to isavuconazole for up to 84 days of treatment. The overall outcome was evaluated according to the clinical, radiological, and mycological responses at Days 42 and 84 and at the end of treatment (EOT). RESULTS: A total of 103 participants were enrolled and received the study drug. The overall response rate of patients with chronic pulmonary aspergillosis in the isavuconazole (52 patients) and voriconazole (27 patients) groups was 82.7% and 77.8% at EOT, respectively. The response rate in patients with cryptococcosis (10 patients, isavuconazole group only) was 90.0%. One of three participants with invasive aspergillosis and one of three participants with mucormycosis responded in the isavuconazole group. In the safety evaluation, the incidence of adverse events in participants with chronic pulmonary aspergillosis was similar in both groups. Adverse drug reactions were reported in 32 (61.5%) patients receiving isavuconazole and 23 (85.2%) patients receiving voriconazole. CONCLUSIONS: Isavuconazole showed efficacy and safety in Japanese patients with chronic pulmonary aspergillosis and cryptococcosis, for which the drug is not currently indicated.

Candidatus Mycoplasma haemohominis in Human, Japan.

Hemotropic mycoplasmas are common pathogens in animals, but it remains unclear what role these pathogens play in human infections. We report clinical and biologic characterization of Candidatus Mycoplasma haemohominis infection in a 42-year-old man in Japan. The patient had severe hemophagocytic syndrome 1 month after an accidental needlestick injury. Metagenomic deep sequencing identified Candidatus M. haemohominis and determined its draft genome for an isolate from serum of the patient. A high copy number of the Candidatus M. haemohominis genome was detected in serum and bone marrow samples. Electron microscopy examination showed morphologic characteristics of Candidatus M. haemohominis. Levofloxacin monotherapy induced resistance caused by a gyrase A gene mutation in the quinolone resistance-determining region, but a combination treatment with moxifloxacin and minocycline was effective. We identified Candidatus M. haemohominis in a patient who had life-threatening symptoms related to multiple organ infection. Human infection with this mycoplasma might occur more frequently than has been generally recognized.

Daily practice and prognostic factors for pneumonia caused by methicillin-resistant Staphylococcus aureus in Japan: A multicenter prospective observational cohort study.

Pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) is associated with poor clinical outcomes. We surveyed clinical outcomes of MRSA pneumonia in daily practice to identify risk factors for the clinical failure and mortality in patients with MRSA pneumonia. This multicenter prospective observational study was performed across 48 Japanese medical institutions. Adult patients with culture-positive MRSA pneumonia were recruited and treated with anti-MRSA antibiotics. The relationships between clinical and microbiological characteristics and clinical outcomes at test of cure (TOC) or 30-day all-cause mortality were analyzed. In total, 199 eligible patients, including nursing and healthcare-associated pneumonia (n = 95), hospital-acquired pneumonia (n = 76), and community-acquired pneumonia (n = 25), received initial treatment with anti-MRSA agents such as vancomycin (n = 135), linezolid (n = 36), or teicoplanin (n = 22). Overall clinical failure rate at TOC and the 30-day mortality rate were 51.1% (48/94 patients) and 33.7% (66/196 patients), respectively. Multivariable logistic regression analyses for vancomycin-treated populations revealed that abnormal white blood cell count (odds ratio [OR] 4.34, 95% confidence interval [CI] 1.31-14.39) was a risk factor for clinical failure and that no therapeutic drug monitoring (OR 3.10, 95% CI 1.35-7.12) and abnormally high C-reactive protein level (OR 3.54, 95% CI 1.26-9.92) were risk factors for mortality. In conclusion, this study provides evidence that majority of MRSA pneumonia patients are initially treated with vancomycin in Japan, and the absence of therapeutic drug monitoring for vancomycin is significantly associated with the mortality in patients with MRSA pneumonia.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of japanese society of chemotherapy, the japanese association for infectious diseases, and the japanese society for clinical microbiology in 2016: General view of the pathogens' antibacterial susceptibility.

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from the patients in Japan was conducted by the Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2016. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period between February 2016 and August 2016 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical Laboratory Standards Institute. Susceptibility testing was evaluated in 1062 strains (143 Staphylococcus aureus, 210 Streptococcus pneumoniae, 17 Streptococcus pyogenes, 248 Haemophilus influenzae, 151 Moraxella catarrhalis, 134 Klebsiella pneumoniae, and 159 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was 48.3%, and those of penicillin-susceptible S. pneumoniae was 99.5%. Among H. influenzae, 14.1% of them were found to be ß-lactamase-producing ampicillin-resistant strains, and 41.1% to be ß-lactamase-non-producing ampicillin-resistant strains. Extended spectrum ß-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo ß-lactamase were 4.5% and 0.6%, respectively.

Essential human resources for antimicrobial stewardship teams in Japan: Estimates from a nationwide survey conducted by the Japanese Society of Chemotherapy.

Implementation of antimicrobial stewardship programs (ASPs) with multidisciplinary antimicrobial stewardship teams (ASTs) is critical for appropriate antimicrobial use at healthcare facilities. Although the Japanese medical reimbursement system was revised to allow fees for ASP implementation, several concerns remain, including understaffing and enforcement of the recommendations on ASTs and ASPs in practice. Furthermore, there are no recommendations on full-time equivalents (FTEs) of the core members in ASTs in Japan. This committee report presents our recommendations on ASTs based on an analysis of the nationwide survey on implemented ASPs and staff FTEs at 1358 healthcare facilities conducted by the Japanese Society of Chemotherapy. Our report provides a directive for structural and financial support of ASTs and should aid in planning for the enhancement of AST practices and the organization of new ASTs.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for clinical microbiology in 2014: General view of the pathogens' antibacterial susceptibility.

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from the patients in Japan was conducted by Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2014. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period between January 2014 and April 2015 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical Laboratory Standards Institute. Susceptibility testing was evaluated in 1534 strains (335 Staphylococcus aureus, 264 Streptococcus pneumoniae, 29 Streptococcus pyogenes, 281 Haemophilus influenzae, 164 Moraxella catarrhalis, 207 Klebsiella pneumoniae, and 254 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was 43.6%, and those of penicillin-susceptible S. pneumoniae was 100%. Among H. influenzae, 8.2% of them were found to be ß-lactamase-producing ampicillin-resistant strains, and 49.1% to be ß-lactamase-non-producing ampicillin-resistant strains. Extended spectrum ß-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo ß-lactamase were 9.2% and 0.4%, respectively.

High burden of Aspergillus fumigatus infection among chronic respiratory diseases.

Aspergillus fumigatus (AF) is a ubiquitous fungus in our environment and causes severe airway disorders. Chronic respiratory diseases (CRDs) are a series of chronic airway and lung diseases. Although both are chronic disorders, however, the relationships between AF and CRDs are still unclear. Therefore, we examined 104 Aspergillus species (spp.) isolated samples in our hospital during three consecutive years to further elucidate the relationships between Aspergillus spp. and CRDs. Based on sample isolates, we then grouped these into two groups, AF and non-AF, to retrospectively analyse the clinical features and to clarify the relationships between AF and CRDs. Importantly, the manifestation of CRD was more frequent in the AF group than in the non-AF group ( p = 0.035). Among CRDs, lung fibrosis was more evident in the AF group ( p = 0.025). Moreover, diabetes mellitus was tended to be evident in AF group than non-AF group ( p = 0.035). In conclusion, CRDs, especially lung fibrosis, were highly prevalent in AF group than non-AF group.

Serotype distribution of Streptococcus pneumoniae isolated from adult respiratory tract infections in nationwide Japanese surveillances from 2006 to 2014.

BACKGROUND AND OBJECTIVE: Reports on the efficacy of pneumococcal conjugate vaccines (PCVs) have been received from many countries. However, in countries where the 7-valent PCV (PCV7) and 13-valent PCV (PCV13) were introduced, overall coverage of the serotypes by the vaccine gradually decreased due to pneumococcal serotype replacement. The aim of this study is to assess the distribution of pneumococcal serotypes and to also provide basic data on adult respiratory infection in Japan. METHODS: We analyzed 1086 Streptococcus pneumoniae strains that had been isolated from respiratory tract infection specimens in adult patients from 2006 to 2014. Capsular typing was performed by the Quellung reaction and multiplex PCR. RESULTS: Among all 1086 strains, serotype 3 was the most common and was identified in 160 strains (14.7%), followed by serotypes 19F, 6B, 19A and 23F. From 2006-10 to 2012-14, the coverage rate of PCV7 tended to gradually decrease. Particularly, serotypes 6B and 19F of penicillin non-susceptible strains decreased. On the other hand, serotypes 19A and 15A of penicillin non-susceptible strains increased. However, coverage by PCV13 of penicillin-resistant S. pneumoniae (PRSP) (penicillin G minimum inhibitory concentration ≥2 µg/mL) remained high (88.7% [2006-10], 88.0% [2012-14]). CONCLUSIONS: In Japan, PCV13 vaccination of adults became available from June 2014. Our study demonstrated that most PRSP (88.0%) still remain covered by PCV13. At present, the introduction of PCV13 in adult clinical practice seems to be highly significant. However, there is a possibility that the distribution has been changing, and careful screening should be continued in the future.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2012: General view of the pathogens' antibacterial susceptibility.

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from the patients in Japan was conducted by Japanese Society of Chemotherapy, Japanese association for infectious diseases and Japanese society for Clinical Microbiology in 2012. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period between January and December in 2012 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical Laboratory Standard Institutes. Susceptibility testing was evaluated in 1236 strains (232 Staphylococcus aureus, 225 Streptococcus pneumoniae, 16 Streptococcus pyogenes, 231 Haemophilus influenzae, 147 Moraxella catarrhalis, 167 Klebsiella pneumoniae and 218 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was 51.3%, and those of penicillin-intermediate S. pneumoniae was 0.4%. Among H. influenzae, 5.6% of them were found to be ß-lactamase-producing ampicillin-resistant strains, and 37.2% to be ß-lactamase-non-producing ampicillin-resistant strains. Extended spectrum ß-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo ß-lactamase were 4.2% and 3.2%, respectively. Continuous national surveillance is important to determine the actual situation of the resistance shown by bacterial respiratory pathogens to antimicrobial agents.

Analysis of Staphylococcal Toxins and Clinical Outcomes of Methicillin-Resistant Staphylococcus aureus Bacteremia.

It is well known that methicillin-resistant Staphylococcus aureus (MRSA) produces many virulence factors, such as hemolysins, leukocidins, proteases, enterotoxins, exfoliative toxins, and immune-modulatory factors. The aim of study was to identify staphylococcal pathogenicity that may affect the prognosis of patients with MRSA bacteremia. We obtained 149 MRSA strains from blood cultures between January 2009 and December 2014 in our institution. We collected information on patient characteristics, laboratory data, staphylococcal toxin genes, and susceptibility of the strain toward anti-MRSA agent and analyzed them as factors contributing to 30-d mortality. The "survival" and "dead" groups consisted of 103 and 46 patients, respectively. Multiple logistic regression analysis showed a four-fold increase in the risk of mortality in patients exhibiting isolated MRSA with staphylococcal enterotoxins (SEs) genes as well as toxic shock syndrome toxin-1 (TSST-1) genes [odds ratio: 3.89; 95% confidence interval: 1.20-12.60; p=0.024]. Kaplan-Meier analysis also showed significantly higher mortality in patient with isolated MRSA with SEs and TSST-1 genes. After adjusting for confounders, the coexistence of SEs and TSST-1 were independently associated with the 30-d mortality compared with treatment and susceptibility. The coexistence of superantigenic toxin genes greatly affects the clinical course and prognosis of patients with MRSA bacteremia.

Effect of interventions by an antimicrobial stewardship team on clinical course and economic outcome in patients with bloodstream infection.

BACKGROUND: Bloodstream infections (BSIs) represent one of the most severe and clinically important conditions in the hospital setting. We have organized an interdisciplinary antimicrobial stewardship team (AST) at our hospital and performed consultations focusing on BSI patients since 2013. This study aimed to evaluate the impact of AST interventions on the diagnosis, treatment, and clinical outcomes of BSI patients. METHODS: We conducted a retrospective quasi-experimental study of BSI patients at a single Japanese university hospital. AST provided recommendations to attending physicians regarding appropriate diagnosis, therapy, and management of BSI patients after reviewing medical charts. RESULTS: We identified a total of 308 cases of BSI from January to December, 2012 (pre-intervention group) and 324 cases of BSI from April, 2013 to March, 2014 (post-intervention group). No significant differences in the in-hospital mortality or 30-day mortality rates were observed between both the groups. Inappropriate therapy was initiated in a significantly lower proportion of patients in the post-intervention group (18.5% vs. 11.4%; P = 0.012). Multivariate analysis confirmed that inappropriate therapy was significantly associated with in-hospital mortality (odds ratio, 2.62; 95% confidence interval, 1.42-4.82; P = 0.002). CONCLUSIONS: An interdisciplinary AST intervention approach decreases the use of inappropriate therapy and may improve clinical outcomes in BSI patients.

Dendritic cell-based immunization ameliorates pulmonary infection with highly virulent Cryptococcus gattii.

Cryptococcosis due to a highly virulent fungus, Cryptococcus gattii, emerged as an infectious disease on Vancouver Island in Canada and surrounding areas in 1999, causing deaths among immunocompetent individuals. Previous studies indicated that C. gattii strain R265 isolated from the Canadian outbreak had immune avoidance or immune suppression capabilities. However, protective immunity against C. gattii has not been identified. In this study, we used a gain-of-function approach to investigate the protective immunity against C. gattii infection using a dendritic cell (DC)-based vaccine. Bone marrow-derived dendritic cells (BMDCs) efficiently engulfed acapsular C. gattii (Δcap60 strain), which resulted in their expression of costimulatory molecules and inflammatory cytokines. This was not observed for BMDCs that were cultured with encapsulated strains. When Δcap60 strain-pulsed BMDCs were transferred to mice prior to intratracheal R265 infection, significant amelioration of pathology, fungal burden, and the survival rate resulted compared with those in controls. Multinucleated giant cells (MGCs) that engulfed fungal cells were significantly increased in the lungs of immunized mice. Interleukin 17A (IL-17A)-, gamma interferon (IFN-γ)-, and tumor necrosis factor alpha (TNF-α)-producing lymphocytes were significantly increased in the spleens and lungs of immunized mice. The protective effect of this DC vaccine was significantly reduced in IFN-γ knockout mice. These results demonstrated that an increase in cytokine-producing lymphocytes and the development of MGCs that engulfed fungal cells were associated with the protection against pulmonary infection with highly virulent C. gattii and suggested that IFN-γ may have been an important mediator for this vaccine-induced protection.

Terminal-stage prognostic analysis in candidemia.

BACKGROUND: Candidemia has an extremely high mortality rate but is not always the direct cause of death. Therefore, determining the effect of candidemia on death is extremely difficult. METHODS: We investigated prognostic factors in patients with culture-proven candidemia at 2 Japanese university teaching hospitals from April 2009 through May 2013. To examine the effects of comorbid conditions, the Charlson comorbidity index was determined, and patients were subjectively classified into 3 clinical prognostic stages (terminal [death expected within 1 month], semiterminal [death expected within 6 months], and nonterminal [expected to live more than 6 months]). The Cox proportional hazard model was used for univariate and multivariate analyses of factors possibly affecting survival. RESULTS: On univariate analysis, factors identified as associated with an increased mortality rate were: admission to an internal medicine department, Candida glabrata, immunosuppression, hypotension, hypoxemia, and a terminal prognostic stage. Factors associated with a decreased mortality rate were: serum albumin, endophthalmitis investigation, and nonterminal prognostic stage. The mortality rate was significantly related to the prognostic stage on multivariate analysis (P < 0.0001), was increased by age (P = 0.0014), and was decreased by a delayed start of antifungal therapy (P = 0.0374). CONCLUSION: In contrast to earlier studies, the present study has found that later antifungal usage is associated with a decreased mortality rate in cases of candidemia. More important than candidemia in causing the deaths of patients with candidemia were the patients' background and comorbidity status. Therefore, rigorous methods should be used when investigating causes of death in terminally ill patients with candidemia.

Efficacy and safety of intravenous sulbactam/ampicillin 3 g 4 times daily in Japanese adults with moderate to severe community-acquired pneumonia: a multicenter, open-label, uncontrolled study.

Although sulbactam/ampicillin (SBT/ABPC) 3 g 4 times daily (QID) is widely used worldwide for patients with moderate to severe community-acquired pneumonia (CAP), the 3 g QID regimen was not available in Japan. In fact, there has been no evidence from a formal clinical study regarding the efficacy and safety of SBT/ABPC 3 g QID in these patients. We report the first results of a multicenter, unblinded, non-comparative, phase 3 study of SBT/ABPC 3 g QID in Japanese adults with moderate to severe CAP. Forty-seven subjects with moderate to severe CAP were enrolled and received SBT/ABPC 3 g QID intravenously for 3-14 days. The clinical responses assessed by the data review committee (DRC) were the primary endpoints. The secondary endpoints included the bacteriological responses assessed by the DRC. The clinical efficacy rate at the test of cure (TOC) was 94.6%. The bacterial eradication rate at TOC was 91.7%. Causative pathogens were isolated from sputum sample taken at baseline in 28 subjects (59.6%). Common causative pathogens included Streptococcus pneumoniae (14 strains), Haemophilus influenzae (9 strains), and Moraxella catarrhalis (8 strains). The clinical efficacy rate and the bacterial eradication rate at TOC of the common pathogens were, respectively, 92.3% and 90.0% in subjects with S. pneumoniae, 83.3% and 75.0% in subjects with H. influenzae, and 87.5% and 87.5% in subjects with M. catarrhalis. All treatment-related adverse events were mild or moderate in severity. SBT/ABPC 3 g QID was well tolerated and demonstrated excellent clinical and bacteriological responses. ClinicalTrials.gov Identifier: NCT01189487.

Correlations between extent of X-ray infiltration and levels of serum C-reactive protein in adult non-severe community-acquired pneumonia.

Pneumonia cases can vary in both severity and chest X-ray findings. Elevated C-reactive protein (CRP) levels may be an indicator of disease severity. We retrospectively evaluated factors correlated with the extent of chest X-ray infiltration both in community-acquired pneumonia (CAP) and a subgroup of cases with pneumococcal pneumonia. In a clinical study that evaluated the efficacy of sitafloxacin, 137 patients with CAP had been previously enrolled. In our study, 75 patients with pneumococcal pneumonia were identified among these 137 CAP patients. The extent of chest X-ray infiltration was scored and correlations with age, sex, body temperature, white blood cell (WBC) count, and CRP levels were analyzed using multivariate analysis with logistic regression. Significant correlations were observed between the extent of chest X-ray infiltration and CRP levels in both CAP and pneumococcal pneumonia. Our data indicates that CRP is a valuable and informative resource that could reflect the severity of pneumonia in cases of both CAP and pneumococcal pneumonia.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2010: General view of the pathogens' antibacterial susceptibility.

The nationwide surveillance on antimicrobial susceptibility of bacterial respiratory pathogens from patients in Japan, was conducted by Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases and Japanese Society for Clinical Microbiology in 2010. The isolates were collected from clinical specimens obtained from well-diagnosed adult patients with respiratory tract infections during the period from January and April 2010 by three societies. Antimicrobial susceptibility testing was conducted at the central reference laboratory according to the method recommended by Clinical and Laboratory Standard Institutes using maximum 45 antibacterial agents. Susceptibility testing was evaluable with 954 strains (206 Staphylococcus aureus, 189 Streptococcus pneumoniae, 4 Streptococcus pyogenes, 182 Haemophilus influenzae, 74 Moraxella catarrhalis, 139 Klebsiella pneumoniae and 160 Pseudomonas aeruginosa). Ratio of methicillin-resistant S. aureus was as high as 50.5%, and those of penicillin-intermediate and -resistant S. pneumoniae were 1.1% and 0.0%, respectively. Among H. influenzae, 17.6% of them were found to be ß-lactamase-non-producing ampicillin (ABPC)-intermediately resistant, 33.5% to be ß-lactamase-non-producing ABPC-resistant and 11.0% to be ß-lactamase-producing ABPC-resistant strains. Extended spectrum ß-lactamase-producing K. pneumoniae and multi-drug resistant P. aeruginosa with metallo ß-lactamase were 2.9% and 0.6%, respectively. Continuous national surveillance of antimicrobial susceptibility of respiratory pathogens is crucial in order to monitor changing patterns of susceptibility and to be able to update treatment recommendations on a regular basis.

Linezolid-resistant Staphylococcus aureus isolated from 2006 through 2008 at six hospitals in Japan.

Limited use of linezolid for treating methicillin-resistant Staphylococcus aureus (MRSA) infection was approved in Japan in 2006. We report here the status of linezolid-resistant MRSAs in Japan. Eleven linezolid-resistant clinical isolates from 11 patients at six hospitals were collected from 2006 through 2008. The minimal inhibitory concentration (MIC) of linezolid in these strains varied from 8 to 64 µg/ml. All strains had at least one G2576T mutation in the chromosomal gene(s) encoding domain V of the 23S ribosomal RNA (rRNA). Chromosomal DNA encoding five copies of the domain V region was analyzed by polymerase chain reaction (PCR). Strains with the linezolid MICs of 64, 32, 16, and 8 µg/ml had the G2576T mutation(s) in four, three (or four), two, and one copy of the 23S rRNA genes, respectively. These results suggest that the level of linezolid resistance seems to be roughly correlated with the number of mutations in the genes encoding 23S rRNA. DNA samples from all 11 strains were subjected to pulsed-field gel electrophoresis and were classified into seven independent clones having >92% identity. Among the 11 patients, five had been treated with linezolid and the remainder, in two hospitals, had no history of prior linezolid use. The results suggested possible nosocomial infections by linezolid-resistant MRSA.

A molecular analysis of quinolone-resistant Haemophilus influenzae: validation of the mutations in Quinolone Resistance-Determining Regions.

The mechanism of quinolone-resistance is considered to be amino acid mutations in the type II topoisomerase. We validated the genetic mechanisms of quinolone resistance in Haemophilus influenzae. We obtained 29 H. influenzae strains from a nationwide surveillance program in Japan (including 11 quinolone-resistant strains [moxifloxacin: MFLX or levofloxacin MIC ≥2 µg/ml]). We analyzed the sequences of the Quinolone Resistance-Determining Regions (QRDRs) in GyrA, GyrB, ParC and ParE. Furthermore, we induced resistance in susceptible strains by exposing them to quinolone, and investigated the relationship between mutations in the QRDRs and the MICs. Five amino acid substitutions in GyrA (at Ser84 and Asp88) and ParC (at Gly82, Ser84 and Glu88) were found to be closely related to the MICs. The strains with a MFLX MIC of 0.125-1 and 2-4 µg/ml had one and two mutations, respectively. The strains with a MFLX MIC of ≥8 µg/ml had three or more mutations. The strains with induced resistance with MFLX MICs of 0.5-1 and ≥2 µg/ml also had one and two mutations, respectively. We confirmed that these five mutations strongly contribute to quinolone resistance and found that the degree of resistance is related to the number of the mutations. In addition, the three strains of 18 susceptible strains (16.7%) also had a single mutation. These strains may therefore be in the initial stage of quinolone resistance. Currently, the frequency of quinolone-resistant H. influenzae is still low. However, as has occurred with ß-lactams, an increase in quinolone use may lead to more quinolone-resistant strains.

Contradiction between in vitro and clinical outcome: intravenous followed by oral azithromycin therapy demonstrated clinical efficacy in macrolide-resistant pneumococcal pneumonia.

UNLABELLED: We conducted a multicenter, unblinded, non-comparative, phase 3 trial of azithromycin-intravenous therapy followed by oral administration in Japanese adults to evaluate clinical efficacy and safety against community-acquired pneumonia in order to obtain regulatory approval for the intravenous formulation in Japan. Azithromycin (500 mg, once daily) was intravenously administered for 2-5 days followed by oral 500 mg once daily administration to complete a total of 7-10 days treatment in 102 adults with moderate-to-severe community-acquired pneumonia. The efficacy rate in the Clinical Per Protocol Set overall was 84.5% (60/71 subjects) on Day 15 (primary analysis). The most common causative pathogen was Haemophilus influenzae (17 strains), followed by Streptococcus pneumoniae (14 strains), Moraxella catarrhalis (5 strains) and Mycoplasma pneumoniae (5 strains). Eleven of 14 S. pneumoniae isolates were resistant to azithromycin (MIC ≥2.0 µg/ml), of which 5 strains with a relatively low MIC of <32 µg/ml had only mef A gene and 6 strains with a high MIC of >64 µg/ml had only the erm B gene except for 2 isolates having both the mef A and erm B genes. Despite dominance of macrolide-resistant strains in Japan, clinical efficacy and bacterial eradication were achieved in 10 of 11 patients (90.9%). Intravenous-to-oral azithromycin therapy demonstrated excellent clinical and bacteriological effects on moderate-to-severe pneumococcal pneumonia despite a high MIC and resistance gene development. This discrepancy is referred to as the "in vivo-in vitro paradox". The current study results provide an insight into this paradox. REGISTRATION NUMBER: NCT00809328.