Identification of a mycobacterial hydrazidase, an isoniazid-hydrolyzing enzyme.

There exists decades-old evidence that some mycobacteria, including Mycobacterium avium and Mycobacterium smegmatis, produce hydrazidase, an enzyme that can hydrolyze the first-line antitubercular agent isoniazid. Despite its importance as a potential resistance factor, no studies have attempted to reveal its identity. In this study, we aimed to isolate and identify M. smegmatis hydrazidase, characterize it, and evaluate its impact on isoniazid resistance. We determined the optimal condition under which M. smegmatis produced the highest amount of hydrazidase, purified the enzyme by column chromatography, and identified it by peptide mass fingerprinting. It was revealed to be PzaA, an enzyme known as pyrazinamidase/nicotinamidase whose physiological role remains unknown. The kinetic constants suggested that this amidase with broad substrate specificity prefers amides to hydrazides as a substrate. Notably, of the five tested compounds, including amides, only isoniazid served as an efficient inducer of pzaA transcription, as revealed by quantitative reverse transcription PCR. Moreover, high expression of PzaA was confirmed to be beneficial for the survival and growth of M. smegmatis in the presence of isoniazid. Thus, our findings suggest a possible role for PzaA, and other hydrazidases yet to be identified, as an intrinsic isoniazid resistance factor of mycobacteria.

Differences in severity of bacteraemia caused by hypermucoviscous and non-hypermucoviscous Klebsiella pneumoniae.

BACKGROUND: Klebsiella pneumoniae strains pose a significant threat to public health. Currently, it is inconclusive whether hypermucoviscous K. pneumoniae (hmKp; semi-quantitatively defined by a positive 'string test') bacteraemia is clinically more severe than non-hmKp bacteraemia. Hence, this systematic review and meta-analysis was conducted with the aim of drawing some conclusions on hypermucoviscosity and bacteraemia. METHODS: PubMed and Web of Science databases were searched for all relevant publications from January 2000 to March 2022. The outcome measures were mortality rate and abscess formation. RESULTS: Fourteen observational studies were included in this systematic review, comprising a total of 3092 patients with K. pneumoniae bacteraemia, including 746 (24.1%) patients with hmKp strains. The meta-analysis showed that hmKp bacteraemia did not account for a significant increase in the incidence of all-cause mortality compared with non-hmKp bacteraemia [pooled hazard ratio 1.30, 95% confidence interval (CI) 0.79-2.12; P=0.30]. However, hmKp bacteraemia was associated with a significant increase in the incidence of abscess formation compared with non-hmKp bacteraemia (pooled odds ratio 7.74, 95% CI 4.96-12.06; P<0.00001). CONCLUSIONS: Although mortality may not be dependent on the causative agent, this review reaffirms the importance of the string test to detect hmKp. There is a need for prudent management, especially for patients with hmKp, that should include investigations for liver abscess and/or metastatic spread, and measures for early and proper source control as this can improve the prognosis.

A Culture Supernatant from an Actinomycete sp. Affects Biofilm Formation and Virulence Expression of Candida auris.

The multidrug-resistant pathogen Candida auris is characterized by its aggregation under certain conditions, which affects its biofilm formation, drug susceptibility, and pathogenicity. Although the innate tendency to aggregate depends on the strain, the mechanism regulating C. auris aggregation remains unclear. We found that the culture supernatant from one of the 95 Actinomyces strains isolated from a deep-sea environment (IMAs2016D-66) inhibited C. auris aggregation. The cells grown in the presence of IMAs2016D-66 exhibited reduced hydrophobicity, biofilm formation, and enhanced proteolytic activity. In addition, the efflux pump activity of the fluconazole-resistant C. auris strain LSEM 3673 was stimulated by IMAs2016D-66, whereas no significant change was observed in the fluconazole-susceptible strain LSEM 0643. As the relationship between aggregative tendency and virulence in C. auris is still unclear, IMAs2016D-66 can serve as a tool for investigating regulatory mechanisms of phenotype switching and virulence expression of C. auris. Understanding of phenotype switching may help us not only to understand the pathogenicity of C. auris, but also to design new drugs that target the molecules regulating virulence factors.

Rifampicin exerts anti-mucoviscous activity against hypervirulent Klebsiella pneumoniae via binding to the RNA polymerase ß subunit.

OBJECTIVES: In hypervirulent Klebsiella pneumoniae (hvKP), the hypermucoviscous capsule is known to be a major virulence determinant. We previously discovered that rifampicin (RFP), a bactericidal drug that binds to and inhibits the ß subunit of RNA polymerase (RpoB), elicits anti-mucoviscous activity against hvKP by suppressing rmpA, a regulator of capsule production. Here, we aimed to determine whether RFP exerts this effect at sub-growth-inhibitory concentrations via its binding to RpoB. METHODS: Five spontaneous RFP-resistant mutants (R1-R5) were prepared from an hvKP clinical isolate and subjected to whole genome sequencing and mucoviscosity analyses. Subsequently, a two-step allelic exchange procedure was used to create a rpoB mutant R6 and revertants with wild-type rpoB from R1-R5 (named R1'-R5'). Transcription levels of rmpA and the capsular polysaccharide polymerase gene magA and capsule thickness of R1-R5 and R1'-R5' grown without or with RFP were evaluated by quantitative reverse transcription polymerase chain reaction and microscopic observation using India ink staining. RESULTS: R1-R5 all had non-synonymous point mutations in rpoB and were highly resistant to the bactericidal effects and anti-mucoviscous activity of RFP. While the properties of R6 were similar to those of R1-R5, the responses of R1'-R5' to RFP were identical to those of the wild type. rmpA and magA transcription levels and capsule thickness correlated well with the mucoviscosity levels. CONCLUSIONS: RFP exerts anti-mucoviscous activity by binding to RpoB. The mechanism of how this causes rmpA suppression remains to be explored.

Discovery of a LuxR-type regulator involved in isoniazid-dependent gene regulation in Mycobacterium smegmatis.

OBJECTIVE: Most non-tuberculous mycobacteria exhibit intrinsic resistance against the anti-tuberculosis drug isoniazid (INH). We previously found that a pyrazinamidase/nicotinamidase of Mycobacterium smegmatis, named PzaA, has an enzymatic activity to hydrolyze INH, which may contribute to intrinsic resistance. Furthermore, PzaA expression is strongly induced by INH under nitrogen-depleted conditions, although the precise mechanism of this phenomenon remains unclear. Here, we aimed to reveal the mechanism underlying the INH-dependent induction of PzaA using a transcriptomic approach. METHODS: RNA sequencing was performed to identify INH-inducible genes other than pzaA. 5' rapid amplification of cDNA ends analysis was employed to identify the transcription start sites of INH-induced transcription units. The function of a LuxR-like regulator gene (MSMEI_1050) found within the gene cluster containing pzaA was confirmed by gene deletion and complementation experiments involving INH hydrolysis assay and quantitative reverse transcription PCR. RESULTS: RNA sequencing revealed 23 genes that INH strongly induced under conditions of nitrogen depletion, 17 of which were in a gene cluster containing pzaA. This cluster comprised at least three transcription units, including a non-INH-inducible monocistronic unit containing MSMEI_1050. Deletion of this gene deprived M. smegmatis of the ability to respond to INH, and complementation restored this ability. CONCLUSIONS: MSMEI_1050 plays a key role in INH-dependent gene regulation. The precise mechanism of action is to be determined in future studies.

Siderophore production as a biomarker for Klebsiella pneumoniae strains that cause sepsis: A pilot study.

BACKGROUND/PURPOSE: Klebsiella pneumoniae bacteremia-induced sepsis is a clinically important condition with a high mortality rate and various known virulence factors. However, studies on the association of these virulence factors with the occurrence of K. pneumoniae bacteremia-induced sepsis are scarce. We aimed to investigate clinical variables and virulence factors in patients with K. pneumoniae bacteremia-induced sepsis. METHODS: We retrospectively reviewed the medical records of 76 patients with K. pneumoniae bacteremia between January 2012 and July 2017. Patients were divided into sepsis (n = 25) and non-sepsis (n = 51) groups. Patient background characteristics, antimicrobial regimens, and prognosis were evaluated. We assessed the distribution of virulence factors related to K. pneumoniae, such as mucoviscosity, capsular polysaccharide, and siderophores. Siderophore production levels were determined by measuring the orange halo zone on chrome azurol S agar plate assay. RESULTS: There were no intergroup differences in male-to-female ratio and age. Multivariable analysis revealed that siderophore production level (p < 0.01) was an independent predictor of K. pneumoniae bacteremia-induced sepsis. Furthermore, the optimal cut-off point of siderophore production to predict sepsis was 9.6 mm (sensitivity, 86%; specificity, 76%; AUC, 0.81). CONCLUSION: Siderophore production was an independent predictor of sepsis caused by K. pneumoniae bacteremia. The optimal cut-off point for siderophore production for sepsis occurrence prediction was 9.6 mm. To improve outcomes, patients with K. pneumoniae bacteremia-induced sepsis with high siderophore production levels should be managed prudently.

Genomic characterization of triple-carbapenemase-producing Acinetobacter baumannii.

OBJECTIVES: To characterize Acinetobacter baumannii OCU_Ac16a, a clinical isolate co-harbouring three acquired carbapenemase genes, bla NDM-1, bla TMB-1, and bla OXA-58, and assess the clinical significance of so-called multiple-carbapenemase producers. METHODS: OCU_Ac16a and its close relative, OCU_Ac16b, which lacks the bla NDM-1, were isolated from sputum cultures of a patient at Osaka City University Hospital. We subjected these strains to whole-genome analysis, particularly focusing on the genetic context of each carbapenemase gene. The transmissibility and functionality of each carbapenemase gene were analysed by conjugation and transformation experiments and antimicrobial susceptibility tests. RESULTS: bla TMB-1 was located in a class 1 integron on the chromosome, whereas bla NDM-1 and bla OXA-58 were found on plasmids named pOCU_Ac16a_2 and pOCU_Ac16a_3, respectively. pOCU_Ac16a_2 (which exhibited highly efficient self-transmissibility) and pOCU_Ac16a_3 (which did not show transmissibility but could be introduced into another A. baumannii strain via electroporation) could both confer carbapenem resistance (MICs ≥512 and ≥32 mg/L, respectively) on the recipient strain. The functionality of bla TMB-1 was evident from the high resistance of OCU_Ac16b to ceftazidime and cefepime (MICs ≥256 and 48 mg/L, respectively), and the high resistance of OCU_Ac16a to cefiderocol (MIC 32 mg/L) could be explained by the additive effect of bla NDM-1 and bla TMB-1. CONCLUSIONS: Our data revealed the genomic organization of OCU_Ac16a and demonstrated that all the carbapenemase genes are functional, each contributing to the extremely high broad-spectrum resistance of OCU_Ac16a to ß-lactams. As multiple-carbapenemase producers can be serious health threats as drug-resistant pathogens and disseminators of carbapenemase genes, close attention should be paid to their emergence.

Nutritional status positively impacts humoral immunity against its Mycobacterium tuberculosis, disease progression, and vaccine development.

Nutritional status contributes to the regulation of immune responses against pathogens, and malnutrition has been considered as a risk factor for tuberculosis (TB). Mycobacterium tuberculosis (Mtb), the causative agent of TB, can modulate host lipid metabolism and induce lipid accumulation in macrophages, where the bacilli adopt a dormant phenotype. In addition, serum lipid components play dual roles in the regulation of and protection from Mtb infection. We analyzed the relationship between nutritional status and the humoral immune response in TB patients. We found that serum HDL levels are positively correlated with the serum IgA specific for Mtb antigens. Analysis of the relationship between serum nutritional parameters and clinical parameters in TB patients showed that serum albumin and CRP levels were negatively correlated before treatment. We also observed reduced serum LDL levels in TB patients following treatment. These findings may provide insight into the role of serum lipids in host immune responses against Mtb infection. Furthermore, improving the nutritional status may enhance vaccination efficacy.

Complete Genome Sequence of Acinetobacter baumannii ATCC 19606T, a Model Strain of Pathogenic Bacteria Causing Nosocomial Infection.

Acinetobacter baumannii ATCC 19606T, which is often used in genetic studies as a routine model microorganism, belongs to sequence type 52 (ST52), showing beta-lactam resistance. We present the complete 3.996-Mbp genome sequence (1 chromosome plus 2 plasmids), generated by combining long-read (MinION) and short-read (MiniSeq) sequencing data.

Clinical and virulence factors related to the 30-day mortality of Klebsiella pneumoniae bacteremia at a tertiary hospital: a case-control study.

Klebsiella pneumoniae bacteremia is a critical clinical presentation that is associated with high mortality. However, extremely few studies have investigated the virulence factors related to mortality of K. pneumoniae bacteremia in patients. The present study elucidated clinical and virulence factors associated with the 30-day mortality of K. pneumoniae bacteremia at a tertiary hospital. The medical records of 129 patients with K. pneumoniae bacteremia admitted to Osaka City University Hospital between January 2012 and December 2018 were retrospectively reviewed. Patient background characteristics, antimicrobial regimens, and prognosis were evaluated. Additionally, virulence factors were assessed using multiplex polymerase chain reaction to elucidate their association with K. pneumoniae. The 30-day mortality was 10.9% in patients with K. pneumoniae bacteremia. The male-to-female ratio, age, and underlying disease did not differ between the non-survivor and survivor groups. Multivariate analysis showed that sepsis (odds ratio (OR), 7.46; p = 0.005) and iutA (OR, 4.47; p = 0.046) were independent predictors associated with the 30-day mortality of K. pneumoniae bacteremia. Despite the relatively low 30-day mortality of patients with K. pneumoniae bacteremia, the treatment of those with sepsis and those infected with K. pneumoniae harboring iutA may require careful management for improving their outcomes.

Clinical characteristics of bacteremia caused by hypermucoviscous Klebsiella pneumoniae at a tertiary hospital.

This study aimed to assess the predictive factors of bacteremia due to hypermucoviscous Klebsiella pneumoniae (hvKP), as well as the mortality. The medical records of 114 patients with K. pneumoniae bacteremia who were divided into the hvKP (n = 24) and non-hvKP (n = 90) groups and were retrospectively reviewed. The male-to-female ratio, age, and underlying disease did not differ between the 2 groups. Mortality was higher among patients in the hvKP bacteremia group than in the non-hvKP bacteremia group (29.2% vs 6.7%). Multivariate analysis showed that the independent predictors associated with hvKP bacteremia were abscess (P = 0.01) and no antibiotic exposure (P = 0.02); thus, early assessment of these conditions is important. For patients with a history of abscess and no antibiotic exposure, it is necessary to administer treatment while keeping the risk of hvKP in mind.

Discovery of anti-mucoviscous activity of rifampicin and its potential as a candidate antivirulence agent against hypervirulent Klebsiella pneumoniae.

A recent increase in the incidence of hypervirulent Klebsiella pneumoniae (hvKP) infections, especially those caused by a sublineage of clonal group CG23 (CG23-I), is raising serious health concerns worldwide. The high virulence of hvKP is, at least in part, attributed to the overproduction of capsular polysaccharide (CPS), which is triggered by a positive regulator of capsular polysaccharide synthesis (cps) genes, named rmpA (regulator of mucoid phenotype A). Although extensive research has been conducted on the mechanisms of hvKP virulence, no study has focused on the development of antivirulence therapeutics. This study attempted to identify and validate an antimicrobial agent able to suppress hvKP hypermucoviscosity. A total of 18 commercially available antimicrobial agents, including ß-lactams, quinolones and aminoglycosides, were tested. Rifampicin (RFP) was found to have strong anti-mucoviscous activity against CG23-I hvKP even at subinhibitory concentrations. Polysaccharide extracts from hvKP showed substantially lowered viscosity when cells were grown with RFP. Moreover, microscopic observations demonstrated that RFP treatment results in a drastic reduction in the thickness of the CPS layer around hvKP cells. RFP treatment decreased transcript levels of rmpA and rmpA-regulated cps genes, indicating that RFP suppresses mucoviscosity of hvKP through inhibition of rmpA transcription. These data suggest that RFP may serve as a potential antivirulence agent for refractory hvKP infection.

Mortality caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae bacteremia; a case control study: alert to Enterobacteriaceae strains with high minimum inhibitory concentrations of piperacillin/tazobactam.

This study aimed to assess the prognostic factors of patients with bacteremia due to extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) as well as the antimicrobial susceptibility, particularly to piperacillin/tazobactam (PTZ), among ESBL-PE strains. The medical records of 65 patients with ESBL-PE bacteremia divided into the survivor group (n = 52) and nonsurvivor group (n = 13) were retrospectively reviewed. The male-to-female ratio, age, underlying disease, leukocyte count, C-reactive protein level, and treatment did not differ between the 2 groups. Multivariate analysis showed that the independent predictors associated with hospital mortality of ESBL-PE bacteremia were sepsis (P = 0.047) and febrile neutropenia (P = 0.008); thus, early assessment of these conditions is important. Further, the minimum inhibitory concentration values of ESBL-PE isolates in nonsurvivors tended to be higher than those in survivors. PTZ should be used with caution in cases of ESBL-PE strains with low susceptibility to the drug.

Genome-Based Epidemiological Analysis of 13 Acinetobacter Strains Isolated from Blood Cultures of Hospitalized Patients from a University Hospital in Japan.

The genus Acinetobacter comprises many species that can cause infectious diseases. Despite their importance as nosocomial pathogens, the clinical distributions of individual species or clones are not well understood. In this study, we aimed to characterize 13 Acinetobacter strains isolated from blood cultures from Osaka City University Hospital. We conducted whole-genome sequencing to reveal their genetic background. We also performed PCR-based open reading frame typing (POT) and compared the results with those of multilocus sequence typing (MLST) to confirm its reliability as a genotyping method. Although biochemical analysis suggested that most isolates were A. baumannii, genomic analysis revealed that the collection of Acinetobacter isolates comprised six different species, with non-baumannii Acinetobacter species representing the majority. All strains possessed an inherent ADC-type ß-lactamase gene, whereas the distribution of OXA-type enzymes was limited to A. baumannii, A. pittii, and A. colistiniresistens. While MLST properly discriminated four A. baumannii strains as different clones, POT failed to distinguish three of the four A. baumannii strains from each other, highlighting a potential pitfall that may be encountered when applying POT to non-epidemiological A. baumannii strains.

Longitudinal Evaluation of Humoral Immunity and Bacterial and Clinical Parameters Reveals That Antigen-Specific Antibodies Suppress Inflammatory Responses in Active Tuberculosis Patients.

A novel tuberculosis vaccine to replace BCG has long been desired. However, recent vaccine trials focused on cell-mediated immunity have failed to produce promising results. It is worth noting that most commercially available successful vaccines rely on humoral immunity. To establish a basic understanding of humoral immunity against tuberculosis, we analyzed and evaluated longitudinal levels and avidity of immunoglobulin to various tuberculosis antigens compared with bacterial and clinical parameters during treatment. We found that levels of IgG antibodies against HrpA and HBHA prior to treatment exhibited a positive correlation with bacterial burden. Analysis of changes in CRP during treatment revealed an association with high levels of specific IgG and IgA antibodies against mycobacterial antigens. Levels of CRP prior to treatment were negatively associated with IgG avidity to CFP-10 and MDP1 and IgA avidity to HrpA, while IgA avidity to MDP1 and Acr exhibited a negative correlation with CRP levels after 60 days of treatment. These results may provide insight for the development of a novel tuberculosis (TB) vaccine candidate to induce protective humoral immunity against tuberculosis.

The Pseudomonas aeruginosa Orphan Quorum Sensing Signal Receptor QscR Regulates Global Quorum Sensing Gene Expression by Activating a Single Linked Operon.

Pseudomonas aeruginosa uses two acyl-homoserine lactone signals and two quorum sensing (QS) transcription factors, LasR and RhlR, to activate dozens of genes. LasR responds to N-3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and RhlR to N-butanoyl-homoserine lactone (C4-HSL). There is a third P. aeruginosa acyl-homoserine-lactone-responsive transcription factor, QscR, which acts to dampen or delay activation of genes by LasR and RhlR by an unknown mechanism. To better understand the role of QscR in P. aeruginosa QS, we performed a chromatin immunoprecipitation analysis, which showed this transcription factor bound the promoter of only a single operon of three genes linked to qscR, PA1895 to PA1897. Other genes that appear to be regulated by QscR in transcriptome studies were not direct targets of QscR. Deletion of PA1897 recapitulates the early QS activation phenotype of a QscR-null mutant, and the phenotype of a QscR-null mutant was complemented by PA1895-1897 but not by PA1897 alone. We conclude that QscR acts to modulate quorum sensing through regulation of a single operon, apparently raising the QS threshold of the population and providing a "brake" on QS autoinduction.IMPORTANCE Quorum sensing, a cell-cell communication system, is broadly distributed among bacteria and is commonly used to regulate the production of shared products. An important consequence of quorum sensing is a delay in production of certain products until the population density is high. The bacterium Pseudomonas aeruginosa has a particularly complicated quorum sensing system involving multiple signals and receptors. One of these receptors, QscR, downregulates gene expression, unlike the other receptors in P. aeruginosa QscR does so by inducing the expression of a single operon whose function provides an element of resistance to a population reaching a quorum. This finding has importance for design of quorum sensing inhibitory strategies and can also inform design of synthetic biological circuits that use quorum sensing receptors to regulate gene expression.

Extracytoplasmic diaphorase activity of Streptomyces coelicolor A3(2).

Metabolism and utilization of plant-derived aromatic substances are fundamental to the saprophytic growth of Streptomyces. Here, we studied an enzyme activity reducing 2,6-dichlorophenolindophenol and nitroblue tetrazolium in the culture supernatant of Streptomyces coelicolor A3(2). N-terminal amino acid sequencing of a nitroblue tetrazolium-reducing enzyme revealed that the enzyme corresponds to the SCO2180 product. The protein exhibited a marked similarity with dihydrolipoamide dehydrogenase, the E3 subunit of 2-oxo-acid dehydrogenase complex. A recombinant SCO2180 protein formed a homodimer and exhibited a diaphorase activity catalyzing NADH-dependent reduction of various quinonic substrates. Similar nitroblue tetrazolium-reducing activities were observed for other Streptomyces strains isolated from soil, implying that the diaphorase-catalyzed reduction of quinonic substances widely occurs in the extracytoplasmic space of Streptomyces.

Two-Component Flavin-Dependent Riboflavin Monooxygenase Degrades Riboflavin in Devosia riboflavina.

The actinobacterium Microbacterium maritypicum splits riboflavin (vitamin B2) into lumichrome and d-ribose. However, such degradation by other bacteria and the involvement of a two-component flavin-dependent monooxygenase (FMO) in the reaction remain unknown. Here we investigated the mechanism of riboflavin degradation by the riboflavin-assimilating alphaproteobacterium Devosia riboflavina (formerly Pseudomonas riboflavina). We found that adding riboflavin to bacterial cultures induced riboflavin-degrading activity and a protein of the FMO family that had 67% amino acid identity with the predicted riboflavin hydrolase (RcaE) of M. maritypicum MF109. The D. riboflavina genome clustered genes encoding the predicted FMO, flavin reductase (FR), ribokinase, and flavokinase, and riboflavin induced their expression. This finding suggests that these genes constitute a mechanism for utilizing riboflavin as a carbon source. Recombinant FMO (rFMO) protein of D. riboflavina oxidized riboflavin in the presence of reduced flavin mononucleotide (FMN) provided by recombinant FR (rFR), oxidized FMN and NADH, and produced stoichiometric amounts of lumichrome and d-ribose. Further investigation of the enzymatic properties of D. riboflavina rFMO indicated that rFMO-rFR coupling accompanied O2 consumption and the generation of enzyme-bound hydroperoxy-FMN, which are characteristic of two-component FMOs. These results suggest that D. riboflavina FMO is involved in hydroperoxy-FMN-dependent mechanisms to oxygenize riboflavin and a riboflavin monooxygenase is necessary for the initial step of riboflavin degradation.IMPORTANCE Whether bacteria utilize either a monooxygenase or a hydrolase for riboflavin degradation has remained obscure. The present study found that a novel riboflavin monooxygenase, not riboflavin hydrolase, facilitated this process in D. riboflavina The riboflavin monooxygenase gene was clustered with flavin reductase, flavokinase, and ribokinase genes, and riboflavin induced their expression and riboflavin-degrading activity. The gene cluster is uniquely distributed in Devosia species and actinobacteria, which have exploited an environmental niche by developing adaptive mechanisms for riboflavin utilization.

Successful Treatment of Intestinal Mycosis Caused by a Simultaneous Infection with Lichtheimia ramosa and Aspergillus calidoustus.

A 53-year-old woman was hospitalized due to septic shock after developing pneumococcal pneumonia after undergoing esophageal cancer surgery. Her transverse colon became perforated after receiving antimicrobial chemotherapy; therefore, emergency subtotal colectomy was performed. Fungi detected in both her colon tissue and a drainage sample indicated intestinal mucormycosis. Early intensive treatment with high-dose liposomal amphotericin B was successful, and she was subsequently discharged from the hospital. The fungal isolates were identified to be Lichtheimia ramosa and Aspergillus calidoustus via gene sequencing using panfungal primers as well as species-specific primers against elongation factor 1 and beta-tubulin for detecting Lichtheimia and Aspergillus, respectively.

Clinical Characteristics and Low Susceptibility to Daptomycin in Enterococcus faecium Bacteremia.

Enterococcus faecium has high levels of resistance to multiple antibiotics, and the mortality due to E. faecium bacteremia is high. Accordingly, E. faecium strains with low susceptibility to daptomycin are a concern in clinical practice. This study assessed the predictive factors and prognosis of patients with bacteremia due to E. faecium as well as the antimicrobial susceptibility, particularly to daptomycin, among E. faecium isolates. The medical records of patients admitted to Osaka City University Hospital with E. faecalis (n = 60) and E. faecium (n = 48) bacteremia between January 2011 and March 2016 were retrospectively reviewed. The E. faecalis group (mean age: 62.0 years) included 22 women, and the E. faecium group (mean age: 59.1 years) included 19 women. Predictive factors for infection, prognosis, and isolate antimicrobial susceptibilities were evaluated. The mean Sequential Organ Failure Assessment score and mortality rate did not differ between the two groups. The independent predictors of E. faecium bacteremia in multivariate analysis included quinolone use (p = 0.025), malignancy (p = 0.021), and prolonged hospitalization (p = 0.016). Cardiovascular disease was associated with a reduced risk of E. faecium bacteremia (p = 0.015). Notably, the percentage of E. faecium isolates with low daptomycin susceptibility was higher than that of E. faecalis (8.5% vs. 0%, p = 0.036). Thus, E. faecium should be considered when administering antibiotic therapy to patients with a history of these predictors. Furthermore, the use of daptomycin should be avoided in case of E. faecium with low susceptibility to daptomycin.