A View on 20 Years of Antimicrobial Resistance in Japan by Two National Surveillance Systems: The National Epidemiological Surveillance of Infectious Diseases and Japan Nosocomial Infections Surveillance

The Ministry of Health, Labour and Welfare (MHLW) of Japan has conducted two national surveillance systems for approximately 20 years to monitor antimicrobial resistance (AMR) in bacteria: the National Epidemiological Surveillance of Infectious Diseases (NESID) and the Japan Nosocomial Infections Surveillance (JANIS). Data accumulated for 20 years by these two surveillance systems have helped depict the epidemiology of the representative AMR bacteria in Japan chronologically. The epidemiology of methicillin-resistant Staphylococcus aureus teaches us that once AMR bacteria have established their high endemicity, controlling such AMR bacteria requires time and is challenging. On the other hand, the epidemiology that multidrug-resistant Acinetobacter sp. exhibits when a strict containment policy for AMR bacteria was introduced in the early phase of its emergence and spread reveals that it is possible to control it. Detailed epidemiology provided by these two different national surveillance systems in Japan enabled us to set up the goal for controlling each AMR bacteria at the hospital level to the prefecture/national level. It is the public health authorities' responsibility to maintain a good surveillance system for AMR bacteria and share the data and findings with healthcare professionals and academicians.

Genomic analysis of antibiotic resistance for Acinetobacter baumannii in a critical care center

Aim

Acinetobacter baumannii is commonly associated with outbreaks and antibiotic‐resistant nosocomial infection. This study aimed to determine the relationship between antibiotic resistance and genotypes of A. baumannii.

Methods

A study was undertaken in the critical care center (CCC) of Juntendo University Urayasu Hospital (Urayasu, Japan) between January 2012 and September 2015. Antimicrobial susceptibility tests were carried out according to the Clinical and Laboratory Standards Institute guidelines. All A. baumannii isolates were verified to carry carbapenemase genes and the ISAba1 element using polymerase chain reaction. The genetic relationship of all A. baumannii isolates was determined by pulsed‐field gel electrophoresis and multilocus sequence typing.

Results

During the study period, 1634 patients were admitted to the CCC. Acinetobacter baumannii was detected in 43 patients (average age, 58 ± 19 years; 67.4% men). Six patients were determined to be extensively drug‐resistant A. baumannii and 21 patients determined to be multidrug‐resistant A. baumannii. Antimicrobial susceptibility linked genotypes of A. baumannii. Molecular characterization by pulsed‐field gel electrophoresis and multilocus sequence typing showed that closely related clones of A. baumannii had spread in the CCC.

Conclusion

Resistance to antimicrobial drugs was significantly associated with certain A. baumannii genotypic types and molecular types. Thus, we might be able to predict whether the genotype has spread in the CCC or not when the susceptibility is examined, facilitating the appropriate isolation of patients.

Comparative analysis of the pathogenicity between multidrug-resistant Acinetobacter baumannii clinical isolates: isolation of highly pathogenic multidrug-resistant A. baumannii and experimental therapeutics with fourth-generation cephalosporin cefozopran

Introduction

The pathogenicity of fatal-outbreak Acinetobacter baumannii isolates has not been fully investigated. This study aimed to compare the pathogenicity between A. baumannii clinical isolates, including multidrug-resistant A. baumannii (MDRA).

Materials and methods

Antibiotic susceptibility was determined by the broth microdilution method, and drug-resistant genes were characterized by PCR and sequencing. The pathogenicity of A. baumannii and antibiotic responses were evaluated using the Galleria mellonella infection model. Clinical isolates from an A. baumannii outbreak at our hospital were categorized using the pulse-field gel electrophoresis. Of the 16 isolated A. baumannii clones, 12 clones were resistant to carbapenems (meropenem and imipenem), of which 10 clones were also resistant to amikacin and ciprofloxacin (MDRAs). MDRAs had OXA-51-like β-lactamase gene harboring an insertion sequence in the promoter region and armA gene encoding 16S rRNA methyltransferase.

Results

Carbapenem- and/or amikacin-resistant A. baumannii were more pathogenic than carbapenem- and/or amikacin-sensitive A. baumannii in G. mellonella. MDRA isolate TK1033 was more virulent than other A. baumannii isolates. However, TK1033 was sensitive to the fourth-generation cephalosporin cefozopran in addition to minocycline, tigecycline, and polymyxins (colistin and polymyxins B) in vitro and in vivo in the MDRA-G. mellonella infection model.

Conclusion

Differences in pathogenicity among carbapenem-resistant A. baumannii clones are consistent with heterogeneous clinical outcomes. Strain TK1033, isolated frequently during the outbreak, was the most virulent, whereas preoutbreak isolate TK1032 was less virulent than other A. baumannii isolates. Infection by high-virulence isolates may be more prevalent during outbreaks. These strains may prove valuable for investigating MDRA virulence and novel therapeutics.

A Epidemiological Investigation of a Nosocomial Outbreak of Multidrug-Resistant Acinetobacter baumannii in a Critical Care Center in Japan, 2011-2012

In 2011, a multidrug-resistant Acinetobacter baumannii (MDRAB) outbreak occurred at a Japanese critical care center (CCC) in a tertiary care hospital. Multidrug-resistance in Japan is defined as resistance to the antimicrobials amikacin, carbapenem, and fluoroquinolone. We conducted a retrospective epidemiological investigation of this outbreak to identify the risk factors for MDRAB respiratory tract acquisition in this hospital. Cases were defined as hospitalized patients with MDRAB-positive cultures at least 3 days post admission to the CCC between June 1, 2011 and April 20, 2012. Fifteen MDRAB cases were identified, including 3 with infection and 12 with colonization. This case-control study demonstrated that hypoalbuminemia along with carbapenem administration were associated with MDRAB respiratory tract acquisition. Pulsed-field gel electrophoresis analysis and multilocus sequence typing using MDRAB isolates suggested a clonal dissemination of MDRAB strains with sequence type 74 occurred primarily among patients admitted to the CCC. From April 16, 2012, a decreased isolation rate of MDRAB in the hospital occurred after the implementation of the following infection control measures: closing the emergency room, discontinuing admission to the CCC, isolating patients with MDRAB colonization or infection to single room status, and conducting environmental cleaning. No MDRAB cases were detected between March 23 and April 20, 2012.

Genotyping of Acinetobacter baumannii strains isolated at a Japanese hospital over five years using targeted next-generation sequencing

Acinetobacter baumannii is a Gram-negative bacterial agent involved in nosocomial infections. In this five-year retrospective study, phylogenetic relationships among carbapenem-resistant A. baumannii strains that were isolated at Teikyo University Hospital in Tokyo metropolis, Japan, were explored. A panel of 72 carbapenem-resistant A. baumannii strains that isolated from January 2006 until August 2010 was studied. Next-Generation sequencing (NGS) was employed to perform large-scale genotyping of these isolates. They were separated, according to the time of isolation, into two genetically distinct groups, one correspondent to strains of the outbreak reported to local public health department in 2010 and the other contained strains from earlier isolations, suggesting different origins of the isolates. Moreover, taxa in each group showed two main clustering patterns. Multilocus sequence typing (MLST) study on 8 isolates from the last outbreak showed that they were from one sequence type, 92, displaying less discriminatory power comparing to large-sequence typing. The clonal lineage profiles produced in this retrospective study will be used as a reference database to compare future isolations of A. baumannii. This study demonstrates the power of NGS in conducting epidemiological researches, allowing a high resolution genotyping.

Mandatory public reporting of healthcare-associated infections in developed countries: how can developing countries follow?

The threat posed by increased transmission of drug-resistant pathogens within healthcare settings and from healthcare settings to the community is very real and alarming. Although the developed world has taken strong steps to curb this menace, there has been little pressure on developing countries to take any corrective action. If the reporting of alarming rates of healthcare-associated infections (HCAIs) from hospitals in India and many other developing countries was made mandatory, it would help to force stakeholders (e.g. healthcare workers, legislators, administrators and policy makers in hospitals) to acknowledge and tackle the problem. This would introduce quality control in a long neglected area of health care, and enable patient empowerment which is practically non-existent in India. Healthcare institutions should commit towards enforcing 'zero tolerance' towards lapses in prevention of HCAIs. Public pressure would force the Indian Government to acknowledge the problem, and to allocate more funds to improve resources and infrastructure; this could substantially elevate the standard of health care given to the average Indian. Despite the numerous challenges, overall public benchmarking of HCAIs is a commendable goal that would go a long way towards tackling this menace in developing countries such as India.

Infection control in healthcare settings in Japan

In Japan, the practice of infection control in healthcare settings has a short history of less than 3 decades. Before that, infection control practices were far from perfect and even ignored. This review summarizes changes in infection control in Japan since the 1980s and offers some comparisons with practices in foreign countries, especially the United States. Infection control is far better now than 25 years ago, but there remain fundamental issues that limit the development of better infection control practices. These problems include insufficient funding and human resources due to the socialized healthcare insurance system in Japan and the lack of interest in infection control research.

Multidrug-resistant Acinetobacter spp.: increasingly problematic nosocomial pathogens

Pathogenic bacteria have increasingly been resisting to antimicrobial therapy. Recently, resistance problem has been relatively much worsened in Gram-negative bacilli. Acinetobacter spp. are typical nosocomial pathogens causing infections and high mortality, almost exclusively in compromised hospital patients. Acinetobacter spp. are intrinsically less susceptible to antibiotics than Enterobacteriaceae, and have propensity to acquire resistance. A surveillance study in Korea in 2009 showed that resistance rates of Acinetobacter spp. were very high: to fluoroquinolone 67%, to amikacin 48%, to ceftazidime 66% and to imipenem 51%. Carbapenem resistance was mostly due to OXA type carbapenemase production in A. baumannii isolates, whereas it was due to metallo-β-lactamase production in non-baumannii Acinetobacter isolates. Colistin-resistant isolates were rare but started to be isolated in Korea. Currently, the infection caused by multidrug-resistant A. baumannii is among the most difficult ones to treat. Analysis at tertiary care hospital in 2010 showed that among the 1,085 isolates of Acinetobacter spp., 14.9% and 41.8% were resistant to seven, and to all eight antimicrobial agents tested, respectively. It is known to be difficult to prevent Acinetobacter spp. infection in hospitalized patients, because the organisms are ubiquitous in hospital environment. Efforts to control resistant bacteria in Korea by hospitals, relevant scientific societies and government agencies have only partially been successful. We need concerted multidisciplinary efforts to preserve the efficacy of currently available antimicrobial agents, by following the principles of antimicrobial stewardship.

Bactericidal activities of woven cotton and nonwoven polypropylene fabrics coated with hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus"

Background

Bacteria from the hospital environment, including linens and curtains, are often responsible for hospital-associated infections. The aim of the present study was to evaluate the bactericidal effects of fabrics coated with the hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite “Earth-plus”.

Methods

Bactericidal activities of woven and nonwoven fabrics coated with Earth-plus were investigated by the time-kill curve method using nine bacterial strains, including three Staphylococcus aureus, three Escherichia coli, and three Pseudomonas aeruginosa strains.

Results

The numbers of viable S. aureus and E. coli cells on both fabrics coated with Earth-plus decreased to below 2 log₁₀ colony-forming units/mL in six hours and reached the detection limit in 18 hours. Viable cell counts of P. aeruginosa on both fabrics coated with Earth-plus could not be detected after 3–6 hours. Viable cells on woven fabrics showed a more rapid decline than those on nonwoven fabrics. Bacterial cell counts of the nine strains on fabrics without Earth-plus failed to decrease even after 18 hours.

Conclusion

Woven cotton and nonwoven polypropylene fabrics were shown to have excellent antibacterial potential. The woven fabric was more bactericidal than the nonwoven fabric.

Lytic myophage Abp53 encodes several proteins similar to those encoded by host Acinetobacter baumannii and phage phiKO2

Acinetobacter baumannii is an important Gram-negative opportunistic pathogen causing nosocomial infections. The emergence of multiple-drug-resistant A. baumannii isolates has increased in recent years. Directed toward phage therapy, a lytic phage of A. baumannii, designated Abp53, was isolated from a sputum sample in this study. Abp53 has an isometric head and a contractile tail with tail fibers (belonging to Myoviridae), a latent period of about 10 min, and a burst size of approximately 150 PFU per infected cell. Abp53 could completely lyse 27% of the A. baumannii isolates tested, which were all multiple drug resistant, but not other bacteria. Mg(2+) enhanced the adsorption and productivity of, and host lysis by, Abp53. Twenty Abp53 virion proteins were visualized in SDS-polyacrylamide gel electrophoresis, with a 47-kDa protein being the predicted major capsid protein. Abp53 has a double-stranded DNA genome of 95 kb. Sequence analyses of a 10-kb region revealed 8 open reading frames. Five of the encoded proteins, including 3 tail components and 2 hypothetical proteins, were similar to proteins encoded by A. baumannii strain ACICU. ORF1176 (one of the tail components, 1,176 amino acids [aa]), which is also similar to tail protein gp21 of Klebsiella phage phiKO2, contained repeated domains similar to those within the ACICU_02717 protein of A. baumannii ACICU and gp21. These findings suggest a common ancestry and horizontal gene transfer during evolution. As phages can expand the host range by domain duplication in tail fiber proteins, repeated domains in ORF1176 might have a similar significance in Abp53.