Comparison of MALDI-TOF mass spectrometry and rpoB gene sequencing for the identification of clinical isolates of Aeromonas spp.

Aeromonas spp., widely present in rivers and soil, cause mild gastroenteritis, severe septicemia, and soft tissue infections in humans. Treatment of these infections require accurate identification of pathogenic Aeromonas spp. However, identification at the species level using conventional methods is highly challenging. In this study, we aimed to compare the accuracy of two different approaches developed for bacterial identification: (i) housekeeping gene sequencing (rpoB) in conjunction with phylogenetic analysis and (ii) matrix-assisted laser desorption ionization mass spectrometry-time of flight (MALDI-TOF MS) (MALDI Biotyper and VITEK MS), for differentiating Aeromonas spp. We analyzed 58 Aeromonas isolates recovered from patients at different medical institutions in Japan using both identification methods. The rpoB sequencing method was the most accurate, identifying all Aeromonas isolates at the species level. Meanwhile, the MALDI Biotyper system correctly identified 53 (91.4%) isolates at the genus level and an additional 30 (51.7%) at the species level. The VITEK MS system correctly identified 58 (100%) isolates at the genus level and an additional 34 (58.6%) at the species level. Thus, MALDI Biotyper and VITEK MS accurately identified isolates at the genus level, but differences were found in the accuracy of identification of species. However, the low cost and ease of analysis make MALDI-TOF MS-based methods strong candidates for use in clinical laboratories that require easy-to-use identification methods.

Nosocomial infections caused by vancomycin-resistant Enterococcus in a Japanese general hospital and molecular genetic analysis.

INTRODUCTION: Vancomycin-resistant Enterococcus (VRE) is a rare bacterium in Japan, but an outbreak due to nosocomial transmission in medical facilities has been reported in recent years. Here, we report the outbreak of vanA vancomycin-resistant Enterococcus faecium (VREfm) in multiple wards of Nara Prefectural General Medical Center in 2019 and results of the molecular epidemiology analysis. METHODS: An aggressive screening program was conducted after the first VREfm was detected in a patient in the A ward. During the outbreak, 6000 rectal swab samples were screened for VRE by culture. Isolates from 60 patients with VREfm detected were clustered using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). RESULTS: PFGE revealed a cluster consisting of three major clusters and four multi-strains. The first major cluster consisted of 26 isolates, the second consisted of 10 isolates, the third consisted of 6 isolates, and the remaining 4 clusters consisted of 2 isolates. MLST identified an allele profile (ST80) in most clusters of clone types P01-P06 but an allele profile (ST992) in cluster P07. CONCLUSION: Based on the PFGE pattern, this case was considered to be a nosocomial infection due to multiple clones. Later, in addition to screening, sharing of hospital information, cohorting of patients and staff, and strengthening of environmental cleanup were carried out, and horizontal infection was suppressed.

A case of Bordetella trematum and Kerstersia gyiorum infections in a patient with congestive dermatitis.

Bordetella trematum and Kerstersia gyiorum are rare gram-negative bacilli that are not frequently detected in human infections. In this report, we describe a case of a 48-year-old man who presented to our hospital with an infected wound on his leg. Discharges from the cracks of the granulation were collected and evaluated in our microbiology laboratory. Gram staining of the specimen showed polymorphonuclear leukocytes and abundant gram-negative bacilli. Three types of colonies were isolated on blood agar and were identified as B. trematum and Alcaligenes faecalis using VITEK MS. Moreover, K. gyiorum and B. trematum were identified and confirmed via 16S ribosomal RNA (rRNA) gene sequencing. The patient successfully recovered following application of meropenem antibacterial therapy and surgical debridement. This is the first reported case of complex wound infection caused by both B. trematum and K. gyiorum. Identification of B. trematum has recently been made possible by routine bacterial identification using matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS). However, K. gyiorum isolation is still rare, and species identification requires 16S rRNA sequencing. Thus, this case highlighted the importance of using multiple methods, such as MALDI-TOF MS and 16S rRNA gene sequencing, for identification of rarely isolated species from clinical specimens.

Burden of Pediatric Central Nervous System Infection and Cost-Benefit Simulation of Multiplex Polymerase Chain Reaction in Japan.

To investigate the clinical use of multiplex polymerase chain reaction (mPCR) in Japan, epidemiological and clinical data for central nervous infections are needed. Here, we report on the epidemiology and economic burden of central nervous system infections and a simulation of the cost-benefit analysis of the Filmarray® Meningitis/Encephalitis (FAME) test for possible clinical use in Japan. We performed FAME tests on samples from 27 patients with pleocytosis aged between 0 and 20 years seen in six community hospitals in Nara and Osaka prefectures. All clinical management procedures were performed without knowledge of the mPCR test results. We analyzed the clinical data and calculated the required reduction in average length of stay for the FAME test to be cost-beneficial. Among the 27 cases, the FAME test revealed causal pathogens in 13 cases (48.1%). The average medical and social costs per case were ¥299,118 ($2,719.2) and ¥171,768 ($1,561.5), respectively. The minimal needed reduction in average length of stay for the FAME test to be cost-beneficial was 0.32- 0.86 days per meningitis case. The result can be informative for evaluating the cost-effectiveness of the clinical use of the FAME test in Japan.

The Epidemiology of Admission-Requiring Pediatric Respiratory Infections in a Japanese Community Hospital Using Multiplex PCR.

Respiratory tract infections (RTIs) are the most common diseases globally among children. This study aimed to assess the epidemiology of admission-requiring pediatric RTI cases and evaluate the effect of the pathogen type on the length of hospital stay (LOS) using the FilmArray® respiratory panel, a multiplex PCR test. The age-specific distribution and seasonality of viruses were investigated between March 26, 2018 and April 12, 2019. Multivariable linear regression analyses were performed to evaluate the effect of pathogen type and coinfection on LOS. Among 153 hospitalized RTI patients, respiratory syncytial virus was the leading cause of hospitalization in infants < 12 months of age (27.7%). Human metapneumovirus and parainfluenza virus were also major causes of hospitalization in patients aged 2-3 years (22.6% and 22.6%, respectively). In the multivariable linear regression model excluding rhinovirus/enterovirus, there was a significant association between viral coinfection and longer LOS (p = 0.012), while single viral infection of any type was not positively correlated with LOS. This study revealed the epidemiology of admission-requiring pediatric RTIs.

The impact analysis of a multiplex PCR respiratory panel for hospitalized pediatric respiratory infections in Japan.

BACKGROUND: Rapid molecular diagnosis of infections has contributed to timely treatments and antimicrobial stewardship. However, the benefit and cost-effectiveness vary in each country or community because they have different standard practices and health care systems. In Japan, rapid antigen tests (RATs) have been frequently used for pediatric respiratory infections. We investigated the impact and cost-effectiveness of a multiplex PCR (mPCR) respiratory panel for pediatric respiratory infections in a Japanese community hospital. METHODS: We replaced RATs with an mPCR respiratory panel (FilmArray®) for admitted pediatric respiratory infections on March 26, 2018. We compared the days of antimicrobial therapy (DOT) and length of stay (LOS) during the mPCR period (March 2018 to April 2019) with those of the RAT period (March 2012 to March 2018). RESULTS: During the RAT and mPCR periods, 1132 and 149 patients were analyzed. The DOT/case was 12.82 vs 8.56 (p < 0.001), and the LOS was 8.18 vs 6.83 days (p = 0.032) in the RAT and mPCR groups, respectively. The total costs during admissions were ∖258,824 ($2331.7) and ∖243,841 ($2196.8)/case, respectively. Pathogen detection rates were 30.2% vs 87.2% (p < 0.001). CONCLUSION: Compared to conventional RATs, the mPCR test contributed to a reduction in the DOT and LOS in a Japanese community hospital for admission-requiring pediatric respiratory infections. However, a proper stewardship program is essential to further reduce the unnecessary usage of antimicrobials.

A simple and feasible antimicrobial stewardship program in a neonatal intensive care unit of a Japanese community hospital.

BACKGROUND: Although tertiary hospitals have successfully introduced ASPs by antimicrobial stewardship teams, lots of community hospitals without pediatric infectious disease specialists have difficulty implementing ASP. We present a successful implementation of simple and feasible NICU antimicrobial stewardship program in a Japanese community hospital. METHOD: We developed a protocol of antimicrobial treatment in our NICU department and have implemented the protocol from September 2017. The protocol consists of start and stop of criteria antimicrobial treatment, weekend report of blood culture result from microbiology department and stopping ordering antimicrobials beforehand for the next day. We compared days of therapy (DOT) during the post-implementation period (September 2017 to August 2018) with that of pre-implementation period (March 2013 to August 2017). RESULT: In pre- and post-ASP implementation periods, 913 and 194 patients were analyzed. DOT was 175.1 and 41.6/1000 patient-days, respectively (p < 0.001) with 76.2% reduction. The percentage of neonates who had any antimicrobials and the percentage of prolonged antimicrobial treatments among neonates who had any antimicrobials decreased significantly (55.3% vs 20.6%, p < 0.001 and 65.0% vs 32.5%, p < 0.001). The protocol compliance rates were also significantly different (55.4% vs 95.4%; p < 0.001). The methicillin-resistant rate of S.aureus rates were significantly reduced in post-ASP period (31.1% vs 12.9%; p = 0.002). CONCLUSION: This ASP program was easily implemented in a NICU department of a community hospital and significantly reduced antimicrobial prescription. This kind of simple protocol may be successfully scaled-up in resource limited community hospitals without no pediatric infectious disease specialists or antimicrobial stewardship team.

Efficacy of routine catheter tip culture in a neonatal intensive care unit.

BACKGROUND: Routine catheter tip cultures are not recommended because some cases of colonization, such as with Staphylococcus aureus, can lead to subsequent bacteremia. To evaluate the safety of colonization without antimicrobial treatment, as well as the effectiveness of routine catheter tip cultures in the neonatal intensive care unit (NICU), we performed a retrospective data analysis in a Japanese community hospital. METHODS: We reviewed all peripherally inserted central venous catheter tip culture results from the NICU ward between April 2012 and June 2017 and noted outcome (i.e. antimicrobial treatment or subsequent infection). We then performed a cost analysis for routine catheter tip culturing on patients who were symptom free during the study period. RESULTS: Of the 93 positive cases in 80 patients from 1,051 catheter tip cultures, seven patients had suspected infection and were treated with antimicrobials. The other 73 symptom-free, positive patients had no subsequent or exacerbated symptoms indicative of an infection, and did not have antimicrobial treatment. The total cost for catheter tip culturing during the study period was ¥548 731. After excluding patients with symptoms of infection at the time of culture, the efficacy of routine catheter tip cultures on symptom-free patients was estimated to be zero. CONCLUSION: Symptom-free colonization did not affect clinician management in this study, and all colonized patients without suspected infection were safely managed without antimicrobials. Furthermore, routine catheter tip culturing was not cost-effective; therefore, this practice may be no longer recommended in the NICU.