The impact of carbapenem shortage and stewardship countermeasures on antimicrobial practice at a tertiary care center.

We evaluated the impact of carbapenem shortage on antimicrobial practice and patient outcome at a tertiary care center. During the shortage, hospital antimicrobial practice could be safely managed through additional antimicrobial stewardship measures including treatment guidance and mandatory preauthorization. Antimicrobial shortage may present a unique opportunity for promoting antimicrobial stewardship.

Chromosomal integration and location on IncT plasmids of the blaCTX-M-2 gene in Proteus mirabilis clinical isolates.

Analysis of five CTX-M-2-producing Proteus mirabilis isolates in Japan demonstrated that bla(CTX-M-2) was located on the chromosome in four isolates and on IncT plasmids in three isolates, including two isolates that also carried the gene on the chromosome. In all four isolates with chromosomal bla(CTX-M-2), ISEcp1 was responsible for the integration of the gene into the chromosome. Three different sites in the P. mirabilis genomic sequence were utilized as integration sites.

A peptide based on homologous sequences of the ß-barrel assembly machinery component BamD potentiates antibiotic susceptibility of Pseudomonas aeruginosa.

OBJECTIVES: The ß-barrel assembly machinery (BAM) complex plays a critical role in outer membrane protein (OMP) biogenesis. The outer membrane (OM) of Pseudomonas aeruginosa is centrally involved in mechanisms of antibiotic resistance. This study aimed to identify effects of a synthetic peptide based on conserved sequences in the putative BamA-binding region of BamD, focusing on antibiotic susceptibility and OMP characteristics in P. aeruginosa. METHODS: We synthesized a peptide FIRL (Phe-Ile-Arg-Leu-CONH(2)) with a sequence related to that of the BamD protein. We assessed antibiotic susceptibility of P. aeruginosa PAO1 using the chequerboard method and a time-kill assay. Changes in OMPs and in OM permeability were examined using SDS-PAGE, western blot analysis and nitrocefin assays. The combined effects of the peptide and antibiotics were investigated using a mouse pneumonia model. RESULTS: Although the peptide alone exerted no antimicrobial effect, it reduced the MICs of colistin, levofloxacin, erythromycin, vancomycin and rifampicin for P. aeruginosa PAO1 by 4-fold or more. Time-kill tests revealed bacterial numbers were significantly reduced after 2 h of incubation with the peptide plus colistin or levofloxacin. Moreover, in the presence of the peptide, expression of OprM was reduced by a third, and OM permeability was increased. The combination of the peptide (2.08 mg/kg) and colistin (1.25 mg/kg) significantly reduced P. aeruginosa by more than 1 log cfu/mL in a mouse pneumonia model. CONCLUSIONS: We show, for the first time, that a synthetic peptide based on homologous sequences of BamD can potentiate antibiotic susceptibility of P. aeruginosa.

Molecular characterization of carbapenem-non-susceptible Acinetobacter spp. in Japan: predominance of multidrug-resistant Acinetobacter baumannii clonal complex 92 and IMP-type metallo-ß-lactamase-producing non-baumannii Acinetobacter species.

We conducted an epidemiological study concerning carbapenem-non-susceptible clinical isolates of Acinetobacter spp. in Japan by molecular procedures including carbapenemase gene identification and amplified ribosomal DNA restriction analysis. Among 598 clinically isolated Acinetobacter spp. in 2007, 27 (4.5%) were non-susceptible to carbapenems. Most carbapenem-non-susceptible Acinetobacter baumannii (13/14) belonged to clonal complex (CC) 92, harbored bla (OXA-51-like) genes, including novel bla (OXA-206), downstream of ISAba1, and were recovered mainly from the Kanto region. Carbapenem-non-susceptible A. baumannii CC92 isolates were further divided by pulsed-field gel electrophoresis into two groups, one of which was characterized by the presence of bla (OXA-23). One A. baumannii CC276 isolate carried bla (IMP-1) and bla (OXA-58). Almost all non-baumannii Acinetobacter isolates (12/13), including Acinetobacter pittii (formerly Acinetobacter genomic species 3) and Acinetobacter nosocomialis (formerly Acinetobacter genomic species 13TU), produced IMP-type metallo-ß-lactamases, and were recovered from various regions in Japan. This is the first report describing the nationwide molecular epidemiology of carbapenem-non-susceptible Acinetobacter spp. with genomic species-level identification in Japan.

Genotyping of skin and soft tissue infection (SSTI)-associated methicillin-resistant Staphylococcus aureus (MRSA) strains among outpatients in a teaching hospital in Japan: application of a phage-open reading frame typing (POT) kit.

We aimed to elucidate the current epidemiological features of outpatient skin and soft tissue infection (SSTI)-associated methicillin-resistant Staphylococcus aureus (MRSA) in Japan. Altogether, we evaluated the performance of a phage-open reading frame typing (POT) kit for genotyping these MRSA strains. We collected 57 MRSA strains from all outpatients with SSTIs attending a teaching hospital in Japan. Drug susceptibility measurement and genotyping including SCCmec typing, spa typing, multilocus sequence typing, pulsed-field gel electrophoresis, and commercial POT-kit were performed. The majority of strains (39 strains, 68 %) had the SCCmec-II element. Seventeen strains (30 %) with SCCmec-IV accounted for the second largest population. Strains with SCCmec-IV and SCCmec-V appeared multiclonal, and a predominance of Panton-Valentine leukocidin (PVL) gene-negative CC8/spa-CC008 strains, as well as the first isolate of an ST93 strain in Japan, was observed among them. Only one USA300 strain was identified. Strains with SCCmec-IV and SCCmec-V were significantly susceptible to antimicrobials. The PVL gene was found in 5 SCCmec-IV strains and 1 SCCmec-V strain. The POT-kit successfully predicted the SCCmec type in 54 strains (95 %), and typing by POT1 scores was highly concordant with SCCmec typing and spa typing. Moreover, three PVL-positive strains fell into a particular POT type (POT scores, 106-77-113). Simpson's index of the POT-kit was 0.977. In conclusion, the present study clarified the multiclonal nature of outpatient SSTI-associated MRSA in a teaching hospital in Japan. These data also underscore the utility of the POT-kit for non-outbreak surveillance through its simple platform consisting of two multiplex PCRs without sequencing.

Development of an enzyme-linked immunosorbent assay system to determine the presence of antibodies specific for taxane structures.

Taxanes, which are widely used in treatment of numerous cancer types, are well-known to induce hypersensitivity reactions (HSR), especially in the case of paclitaxel. Although the cause of the HSR is commonly thought to be a non-immunological direct effect of the diluent which is used to dissolve paclitaxel, some reports suggest the possibility of the presence of an immunological reaction to the common taxane structure. The aim of this study was to establish a method to determine the presence of anti-taxane antibodies in body fluids of patients who have previously received paclitaxel, in order to estimate the risk of the occurrence of HSR to other taxane compounds, such as docetaxel. To prepare an enzyme-linked immunosorbent assay (ELISA) plate for determining taxanes, 10-deacetylbaccatin III (DAB) was first succinylated by use of dimethylaminopyridine and succinic anhydride in dried pyridine. After the succinylation reaction, three different products were obtained, and these were confirmed as 7-succinoyl DAB (7-DAB), 10-succinoyl DAB (10-DAB), and 7,10-disuccinoyl DAB (7,10-DAB) by (1)H-NMR analysis. Each of these three products was conjugated with bovine serum albumin (BSA), and adsorbed on an ELISA plate. By using a commercially available anti-taxane monoclonal antibody as a model antibody, the detection limit of the anti-taxane antibodies on the 7-DAB-BSA-, 10-DAB-BSA-, and 7,10-DAB-BSA-conjugated ELISA plate was estimated as 0.3, 1 and 10 ng/ml, respectively. The ELISA system established in this study may therefore be useful for estimating the risk of HSR to taxanes in a patient prior to the use of these drugs.

Risk factors for and role of OprD protein in increasing minimal inhibitory concentrations of carbapenems in clinical isolates of Pseudomonas aeruginosa.

PURPOSE: This study examined the risk factors for, and molecular mechanisms underlying, the increase in carbapenem minimum inhibitory concentrations (MICs) in clinical isolates of Pseudomonas aeruginosa. METHODOLOGY: Consecutive clinical isolates of P. aeruginosa were collected. The MicroScan WalkAway system detected more than fourfold increases in the MICs of carbapenems in P. aeruginosa isolates serially recovered from some patients during their clinical course. The clinical risk factors associated with this increase were examined by multiple logistic regression analysis. Western blot analysis and nucleotide sequencing of the oprD gene of 19 clonally related and paired P. aeruginosa isolates from the same patients were undertaken to examine the mechanisms underlying the increase in MICs. RESULTS: The results showed that prior use of carbapenems (OR, 2.799; 95 % CI, 1.088-7.200; P=0.033) and the use of ventilators or tracheostomies (OR, 2.648; 95 % CI, 1.051-6.671; P=0.039) were risk factors for increased carbapenem MICs. Analysis of the underlying mechanisms revealed that loss of functional OprD protein due to mutation of the oprD gene tended to occur in P. aeruginosa isolates with imipenem MICs of more than 8 µg ml-1; a reduction in OprD expression was observed in P. aeruginosa isolates with imipenem MICs of 4 or 8 µg ml-1. This difference in the resistance mechanism was not correlated with the MICs of meropenem. CONCLUSION: This difference in the resistance mechanism of P. aeruginosa indicates a critical breakpoint at an imipenem MIC of 8 µg ml-1, in accordance with EUCAST criteria. Reducing carbapenem use will prevent P. aeruginosa clinical isolates from developing resistance to carbapenems.

The first point prevalence survey of health care-associated infection and antimicrobial use in a Japanese university hospital: A pilot study.

BACKGROUND: Point prevalence surveys (PPSs) in Japanese hospitals have not yet been reported. The purpose of this pilot PPS study was to evaluate the epidemiology of health care-associated infections (HAIs) and antimicrobial use in a Japanese tertiary university hospital. METHODS: A 1-day, cross-sectional PPS was performed at a Japanese university hospital. Data on demographics, active HAIs, and antimicrobial use of all inpatients were collected using a data collection form. RESULTS: Of 841 patients, 85 (10.1%) had 90 active HAIs, and 308 patients (36.6%) were administered 494 antimicrobials. Among the 90 HAIs and 58 pathogens, the most frequent infection and isolated pathogen were pneumonia (20.0%) and Enterobacteriaceae (27.6%), respectively. Of the 118 antimicrobials used for treatment of HAIs, carbapenems were the most frequently administered category of antimicrobials (22.9%). In regard to antimicrobials for surgical prophylaxis, 37 of 119 (31.1%) were administered to patients on postoperative day 3 or later, and 48 of 119 (40.3%) were administered orally. CONCLUSIONS: The incidence of HAIs is higher than in other developed countries. The social and medical situation in Japan may affect patient demographics, active HAIs, and antimicrobial use. Multicenter PPSs are necessary to uncover the real epidemiology of HAIs and antimicrobial use in Japan.

Successful treatment of fulminant community-acquired Pseudomonas aeruginosa necrotizing pneumonia in a previously healthy young man.

This report presents a case of fulminant community-acquired Pseudomonas aeruginosa necrotizing pneumonia in a previously healthy young man, including an analysis of the virulence of the P.aeruginosa isolated from the patient. The patient was successfully treated with intensive care and antibiotic treatment. This study analyzed the pathogenicity of the isolated strain both in vivo (using a mouse pneumonia model) and in vitro (using biofilm production), but could not explain how an otherwise healthy young man developed such severe community-acquired P.aeruginosa pneumonia. Although rare in community-acquired pneumonia, P.aeruginosa infection should be considered in patients with severe rapidly progressive pneumonia.

Evaluation of antimicrobial susceptibility for ß-lactams against clinical isolates from 51 medical centers in Japan (2008).

This antimicrobial resistance surveillance study was performed in 51 medical centers in Japan over an 11-year period. The susceptibilities of 4228 strains including Escherichia coli (491 strains), Klebsiella spp. (462 strains), Enterobacter spp. (459 strains), Citrobacter freundii (358 strains), indole-positive Proteus spp. (386 strains), Serratia spp. (443 strains), Acinetobacter spp. (327 strains), Pseudomonas aeruginosa (473 strains), oxacillin-susceptible Staphylococcus aureus (481 strains), and coagulase-negative staphylococci (CoNS; 348 strains) were tested with 7 ß-lactams (cefepime, cefpirome, ceftazidime, cefoperazone/sulbactam, imipenem, and piperacillin for gram-negative bacteria, or oxacillin for gram-positive bacteria). No resistance to these ß-lactams (with the exception of ceftazidime) was found in oxacillin-susceptible S. aureus and CoNS. Of the E. coli clinical isolates, 24.6% were resistant to piperacillin, whereas 3.5% or less (cefpirome = 4.5%) were resistant to other ß-lactam agents. Klebsiella spp. isolates were more susceptible to imipenem (99.6%), cefepime (98.7%), ceftazidime (98.5%), cefpirome (97.6%), and cefoperazone/sulbactam (97.6%). Isolates of Enterobacter spp., C. freundii, and Serratia spp. were susceptible to imipenem, cefepime, and cefpirome as well. The sensitivities of these organisms against cefepime and cefoperazone/sulbactam were 100%. Acinetobacter spp. isolates were less resistant to cefoperazone/sulbactam (0.6% resistance), imipenem (0.9%), and ceftazidime (2.8%) compared with other ß-lactam antibiotics tested. Isolates of P. aeruginosa were more susceptible to piperacillin (9.1% resistance), cefoperazone/sulbactam (9.5%), and cefepime (6.6%) compared with ceftazidime (10.8%), cefpirome (16.3%), and imipenem (23.5%). The proportion of strains resistant to ß-lactam antimicrobials has decreased compared with data from 2006 (Diagn. Microbiol. Infect. Dis. 60:177-183), reflecting the reduced consumption of ß-lactams in Japan.