In vitro activity of tedizolid against 43 species of Nocardia species.

The purpose of the present study was to evaluate the in vitro activity of tedizolid against several clinically significant species of Nocardia by comparing with that of linezolid. A total of 286 isolates of Nocardia species, including 236 clinical isolates recovered from patients in Japan and 50 strains (43 species) purchased from NITE Biological Resource Center, were studied. Antimicrobial susceptibility testing was performed using the broth microdilution method. For the 286 Nocardia isolates, the minimal inhibitory concentration (MIC)50 and MIC90 values of tedizolid were 0.25 and 0.5 µg/ml, and those of linezolid were 2 and 2 µg/ml, respectively. The distribution of the linezolid/tedizolid ratios (MICs of linezolid/MICs of tedizolid) showed that tedizolid had four- to eight-fold higher activity than linezolid in 96.1% (275/286) of Nocardia isolates. Both the tedizolid and linezolid MIC90 values for Nocardia brasiliensis were two-fold higher than those for the other Nocardia species. Both tedizolid and linezolid had low MIC values, 0.25-1 µg/ml and 0.5-4 µg/ml, respectively, even against nine isolates (five species) that were resistant to trimethoprim/sulfamethoxazole. One Nocardia sputorum isolate showed reduced susceptibility to tedizolid (4 µg/ml). Bioinformatics analysis suggests different resistance mechanisms than the oxazolidinone resistance seen in enterococci and staphylococci.

A Multicenter Study on the Utility of Selective Enrichment Broth for Detection of Group B Streptococcus in Pregnant Women in Japan.

Universal screening for Streptococcus agalactiae, Group B Streptococcus (GBS), in pregnant women is important for preventing severe infectious diseases in neonates. The subculture method using selective enrichment broth has been reported to significantly improve GBS detection in the US; however, this method is not widely practiced in Japan. An insufficiency of large-scale validation is one of the reasons; therefore, we validated the utility of the subculture method in collaboration with multiple facilities. A total of 1957 vaginal-rectal swab specimens were obtained from pregnant women at 35-37 gestational weeks from March 1, 2020 to August 30, 2020 at Fukushima Medical University Hospital, Aiiku Hospital, Kitano Hospital, and the University of the Ryukyus Hospital. Three methods, such as conventional direct agar plating, subculture using selective enrichment broth, and direct latex agglutination (LA) testing with incubated broth were performed for GBS detection and discrepant results were confirmed using real-time PCR. The GBS detection rates for direct agar plating, subculture, and direct LA testing were 18.2% (357/1957), 21.6% (423/1957), and 22.3% (437/1957), respectively. The use of selective enrichment broth showed results in highly-sensitive GBS detection and is therefore recommended for GBS screening to prevent GBS-related infectious diseases in neonates in Japan.

Nocardia sputorum sp. nov., an actinobacterium isolated from clinical specimens in Japan.

Two novel actinobacteria, designated IFM 12276T and IFM 12275, were isolated from clinical specimens in Japan, and their taxonomic positions were investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strains IFM 12276 T and IFM 12275 have completely identical 16S rRNA gene sequences and were closely related to members of the genus Nocardia. The highest 16S rRNA gene sequence similarity was observed to Nocardia beijingensis (99.6 %) and Nocarida sputi (99.6 %), followed by Nocardia niwae (99.3 %) and Nocardia araoensis (99.3 %). The whole-cell hydrolysates of strains IFM 12276T and IFM 12275 contained meso-diaminopimelic acid, arabinose and galactose. The acyl type of muramic acid was N-glycolyl. The predominant isoprenoid quinone was MK-8(H4, ω-cycl.) and the principal polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. Strains IFM 12276T and IFM 12275 contained mycolic acids that co-migrated with those from the type strain of N. niwae. These chemotaxonomic features corresponded to those of the genus Nocardia. Meanwhile, the differences in some phenotypic characteristics, along with the results of average nucleotide identity and digital DNA-DNA hybridization analyses, indicated that strains IFM 12276 T and IFM 12275 should be distinguished from the recognized species of the genus Nocardia. Therefore, these strains represent a novel species of the genus Nocardia, for which the name Nocardia sputorum sp. nov. is proposed. The type strain is IFM 12276T (=NBRC 115477T=TBRC 17096T).

Detection of Clostridioides difficile toxin B gene in clinical stool specimens using rapid diagnostic quenching probe-polymerase chain reaction assay.

We tested the accuracy of quenching probe-polymerase chain reaction (QP-PCR) for detecting Clostridioides difficile toxin B gene (tcdB) in stools from inpatients with suspected C. difficile infection and compared the results with other nucleic acid amplification tests (NAATs). Toxigenic culture results were used as reference for comparison. QP-PCR had comparable diagnostic accuracy with other NAATs and prior bead-beating enabled detection of tcdB in specimens judged as negative, without bead-beating. Taken together, the QP-PCR either with or without bead-beating showed sufficient effectiveness for detecting tcdB in stool specimens.

Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry with Time-of-Flight Peak Analysis for Rapid and Accurate Detection of Group B Streptococcus in Pregnant Women.

Severe infections in neonates caused by Streptococcus agalactiae, Group B Streptococcus (GBS), are often associated with GBS transmission from their mothers during labor or birth. Hence, it is necessary to develop a universal method for screening vaginal-rectal GBS colonization in pregnant women worldwide. A subculture of vaginal-rectal swabs using a selective enrichment broth and an agar plate is conventionally recommended for GBS screening. However, infants born to mothers who are GBS negative on subculture sometimes contract GBS infections. Therefore, we developed another method with high sensitivity for GBS screening. A total of 178 vaginal-rectal swabs from pregnant women were inoculated into the enrichment broth, of which 126 were suspected of containing GBS due to the change in the color of the broth. The subculture results were positive for GBS in 34 (27.0%) swabs. Each broth was then analyzed using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Analysis of the TOF peaks specific to GBS revealed 45 (35.7%) swabs as GBS positive. Of the 11 GBS positive samples on TOF peak analysis but negative on subculture, S. agalactiae gene targets were detected through PCR in 4 samples. MALDI detection with analysis of peaks of TOF (MDAPT) can detect GBS directly from cultured broth with high sensitivity. MDAPT can be an alternative method for GBS screening in pregnant women and contribute to the prevention of severe GBS infectious diseases in neonates. IMPORTANCE As previously reported, 10%-30% of pregnant women carry Streptococcus agalactiae, Group B Streptococcus (GBS), in their vagina or rectum, and approximately 50% of them vertically transmit GBS to their neonates during labor or birth. Moreover, 1%-2% of the GBS-transmitted neonates develop severe GBS infectious diseases, which have a mortality rate of 19.2% in a preterm infant and 2.1% in a full-term infant. Hence, universal screening for GBS colonization in pregnant women is conducted worldwide using the subculture procedure; however, infants born to GBS negative mothers sometimes contract GBS infections. Therefore, other laboratory techniques are required for detecting GBS more accurately. The proposed method "MALDI detection with analysis of peaks of TOF (MDAPT)" detects GBS directly from cultured broth with high sensitivity. Therefore, it can be an alternative method for GBS screening in pregnant women, thereby contributing to the prevention of severe GBS infectious diseases in neonates.

Identification and antimicrobial susceptibility profiles of Nocardia species clinically isolated in Japan.

The aims of the present study were to profile the antimicrobial susceptibility patterns of a diverse range of Nocardia species isolated in Japan, and to determine the ability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for species/complex identification. Identification of 153 clinical isolates was performed by full-length 16S rRNA gene sequencing as a reference method to evaluate the usefulness of MALDI-TOF MS identification. Antimicrobial susceptibility testing (AST) for 14 antibiotics was performed using the broth microdilution method against 146 of the isolates. Among the total 153 clinical isolates, Nocardia farcinica complex (25%) was the most common species, followed by Nocardia cyriacigeorgica (18%), Nocardia brasiliensis (9%), Nocardia nova (8%), and Nocardia otitidiscaviarum (7%). Among 150 isolates identified to the species/complex level by 16S rRNA gene sequencing, MALDI-TOF MS with the use of a supplemental Nocardia library (JMLD library ver.ML01) correctly identified 97.3% (n = 146) to the species/complex level and 1.3% (n = 2) to the genus level. Among the 146 Nocardia isolates that underwent AST, the susceptibilities were 100% to linezolid, 96% to amikacin, 94% to trimethoprim-sulfamethoxazole, and 76% to imipenem. None of the trimethoprim-sulfamethoxazole-resistant isolates carried either plasmid-mediated sulfonamide-resistant genes (sul1, sul2) or trimethoprim-resistant genes (dfrA).

Complete Genome Sequence of Multidrug-Resistant Strain Nocardia wallacei FMUON74, Isolated from a Sputum Culture.

Nocardia wallacei is one of the members of the N. transvalensis complex which possess a highly unique susceptibility pattern. Here, we describe the closed complete genome sequence of the multidrug-resistant strain N. wallacei FMUON74, which was obtained using a hybrid approach combining Nanopore long-read sequencing and Illumina and DNBseq short-read sequencing.

Validation of MALDI-TOF MS devices in reanalysis of unidentified pathogenic bacteria detected in blood cultures.

In hospital microbial laboratories, morphological and biochemical analyses are performed to identify pathogenic microbes;however, these procedures lack rapidity and accuracy. Recently, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has been clinically utilized, and is expected to enable rapid and accurate microbial identification. We aimed to validate two MALDI-TOF MS devices available in Japan: the VITEK-MS (BioMérieux) and the Microflex LT (Bruker Daltonics). Clinically isolated bacteria, 100 samples in all, detected in blood cultures but incompletely identified by conventional procedures, were reanalyzed using the two devices. The VITEK-MS and Microflex LT, respectively, identified 49% (49/100) and 80% (80/100) of the tested bacteria at the species level, as well as 96% (96/100) and 95% (95/100) at the genus level. Among those reidentified strains, 26% (26/100) at the species level and 88% (88/100) at the genus level were concordant with each other, though three strains were unmatched. Moreover, four bacterial strains were unable to be identified using the VITEK-MS, versus five using the Microflex LT. MALDI-TOF MS devices can provide more rapid and accurate bacterial identification than ever before;however, the characteristics of each system were slightly different;therefore, it is necessary to understand the difference in performance of MALDI-TOF MS models.

Amyloid precursor protein 770 is specifically expressed and released from platelets.

Platelets not only play an essential role in hemostasis after vascular injury but are also involved in the development of coronary artery disease (CAD) and cerebrovascular lesions. Patients with CAD and cerebral ischemia are recommended to undergo antiplatelet therapy, but they have an increased incidence of major bleeding complications. Both assessment of the platelet activation status and response to antiplatelet therapy in each patient are highly desired. ß-Amyloid precursor protein (APP) 770 is expressed in vascular endothelial cells, and its extracellular region, a soluble form of APP770 (sAPP770, also called nexin-2), is proteolytically cleaved for shedding. Abundant sAPP770 is also released from activated platelets. In this study, we used peripheral blood samples from patients with CAD and control subjects and evaluated sAPP770 as a specific biomarker for platelet activation. First, the plasma levels of sAPP770 correlated well with those of the soluble form CD40 ligand (CD40L), an established biomarker for platelet activation. Additionally, flow cytometry analysis using peripheral blood cells showed that CD40L expression is up-regulated in activated T cells, whereas APP770 expression is negligible in all blood cell types except platelets. Following stimulation with collagen or ADP, aggregating platelets immediately released sAPP770. Finally, patients with dual antiplatelet therapy showed significantly lower levels of plasma sAPP770 than those with no therapy. Taken together, our data show that plasma sAPP770 could be a promising biomarker for platelet activation.

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.

Laboratory surveillance of antimicrobial resistance and multidrug resistance among Streptococcus pneumoniae isolated in the Kinki region of Japan, 2001-2015.

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced among children in Japan in 2010. There are no long-term multicenter surveillance studies of antimicrobial resistance in S. pneumoniae before and after the introduction of PCV7. Therefore, we examined chronological trends in antimicrobial resistance among 4534 strains of S. pneumoniae isolated from both children and adults in the Kinki region of Japan during 2001-2015. High-level penicillin and third-generation cephalosporin resistance in S. pneumoniae increased among both children and adults during the period before the introduction of PCV7 (2001-2010). Besides penicillin and cephalosporin, pneumococcal carbapenem and macrolide resistance increased among children. The rate of resistance to these antibiotics was higher among children than among adults. The introduction of PCV7 decreased the rate of non-susceptibility to ß-lactam antibiotics and the rate of multidrug resistant S. pneumoniae among children, but not among adults.

Evaluation of the FilmArray Blood Culture Identification Panel on Detection of Pathogenic Microorganisms in Positive Blood Cultures: the First Clinical Report in Japan.

FilmArray (FA) is a multiplex PCR-based desktop microbial detection system. The blood culture identification (BCID) panel is an adaptable panel for FA, which diagnoses sepsis and/or systemic infections by detecting 14 bacterial species, 4 bacterial genera, 1 bacterial family, 5 yeast species, and 3 antimicrobial resistance genes (mecA, Klebsiella pneumoniae carbapenemase [KPC], and vanA/B) in positive blood cultures within 1 h. We retrospectively evaluated the FA-BCID panel using 54 positive blood cultures, in which 57 bacterial and 3 yeast strains were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The FA-BCID panel revealed 59 microorganisms in 53 samples; this performance was similar to that of MALDI-TOF MS analysis; however, 1 bacterium in 1 sample was not detected. In addition, mecA genes were detected in 12 Staphylococcus species, which all manifested methicillin resistance in susceptibility testing, whereas genes KPC and vanA/B were not detected, in agreement with the results of antimicrobial susceptibility testing. Although more information on antimicrobial resistance, including activity of IMP-metallo-ß-lactamases, is required in Japan, the FA-BCID panel can detect pathogenic microorganisms in positive blood cultures rapidly, and this method could be beneficial for proper treatment of sepsis and/or systemic infections, especially in small hospitals.

Endogenous Fusarium Endophthalmitis During Treatment for Acute Myeloid Leukemia, Successfully Treated with 25-Gauge Vitrectomy and Antifungal Medications.

Endogenous fungal endophthalmitis (EFE) caused by disseminated fusariosis is a rare condition that generally has a poor outcome, even with intensive therapy. Here, we describe a case in which this type of EFE was diagnosed with vitreous sampling and was successfully treated with 25-gauge vitrectomy and antifungals, including liposomal amphotericin B and voriconazole. A 16-year-old male patient undergoing treatment for acute myeloid leukemia complained of eye pain and blurred vision in his right eye. Treatment was initiated for a vitreous opacity, possibly associated with herpetic retinitis, but the patient worsened and he was referred to us. Right-eye visual acuity was limited to light perception. We suspected endogenous endophthalmitis and performed 25-gauge vitrectomy with antibiotic perfusion of ceftazidime, vancomycin, and voriconazole. Vitreous culturing revealed the presence of Fusarium solani species complex, and enhanced computed tomography revealed disseminated fusariosis lesions in the lung, spleen, and the soft tissue of the left upper arm. The patient received antifungal treatment with liposomal amphotericin B and voriconazole, and these conditions were eliminated. Visual acuity recovered to 20/400 after additional vitrectomy for tractional retinal detachment and was maintained at this level during the 6-month follow-up period. The success of our treatment allowed the capture of optical coherence tomography images of the retina during fusarium-associated endogenous endophthalmitis and the follow-up period. Furthermore, this case showed that immediate vitrectomy for suspected EFE and intensive treatment can lead to a good clinical outcome.

Endophthalmitis associated with Purpureocillium lilacinum during infliximab treatment for surgically induced necrotizing scleritis, successfully treated with 27-gauge vitrectomy.

PURPOSE: To report a case of endophthalmitis associated with Purpureocillium lilacinum (P. lilacinum) during infliximab treatment for surgically induced necrotizing scleritis, successfully treated with 27-gauge vitrectomy. METHODS: A single case report. RESULTS: A 71-year-old man who had undergone immunosuppressive therapy, including infliximab, for surgically induced necrotizing scleritis (SINS) in his left eye complained of visual disturbance and eye pain in the eye. He had a past history of surgery for recurrent pterygium: pterygium excision, amnion transplantation with mitomycin C and limbal transplantation. Visual acuity in the left eye was counting fingers at 30 cm, and intraocular pressure was 3.0 mmHg. Slit-lamp examination revealed the presence of anterior chamber cells (3+), and a B-mode ultrasound scan showed a vitreous opacity. We made a diagnosis of endophthalmitis and performed 27-gauge microincision vitrectomy surgery (27GMIVS) with antibiotic perfusion of ceftazidime, vancomycin and voriconazole. Intraoperative findings included a fungus-like ball-shaped opacity in the vitreous, and a close-to-normal retinal appearance. A vitreous body culture identified the presence of P. lilacinum. After 2 months of antibacterial and antifungal therapy, inflammation decreased and visual acuity recovered to 20/100. CONCLUSIONS: This is the first report of a case of endophthalmitis associated with P. lilacinum during infliximab treatment for SINS. Scleral thinning due to necrotizing scleritis, especially during immunosuppressive therapy, is a risk factor for endophthalmitis. We found that 27GMIVS was a useful strategy for such a challenging clinical situation.

A Chronic Respiratory Pasteurella multocida Infection Is Well-Controlled by Long-Term Macrolide Therapy.

A 57-year-old woman with severe bronchiectasis frequently received antibiotics, including penicillin, for acute exacerbations due to Pasteurella multocida. Although the bacteria showed a decrease in antibiotic susceptibility, her symptoms and X-ray findings became stable, and severe exacerbations were not observed for the last few years after a low-dose erythromycin treatment was started. The development of a respiratory infection with Pasteurella multocida is relatively uncommon, but it can be controlled by immunomodulation which is associated with long-term macrolide therapy.

Predominance of PCR-ribotypes, 018 (smz) and 369 (trf) of Clostridium difficile in Japan: a potential relationship with other global circulating strains?

Global spread and evolutionary links of an epidemic Clostridium difficile strain (PCR-ribotype 027) have been noted in recent decades. However, in Japan, no outbreaks caused by type 027 have been reported to date. A total of 120 C. difficile isolates from patients at 15 hospitals during non-outbreak seasons between 2011 and 2013 as well as 18 and 21 isolates collected from two hospitals in 2010 and 2009, respectively, in outbreak periods in Japan, were examined. Among these 120 isolates, Japan-ribotypes smz and ysmz (subtype variant of smz) were the most predominant (39.2 %) followed by Japan-ribotype trf (15.8 %). Types smz/ysmz and trf were also concurrently predominant at two hospitals in the outbreak settings. Out of the five binary toxin-positive isolates observed, only one was PCR-ribotype 027 and another PCR-ribotype 078. Type smz was later found to correspond to PCR-ribotype 018. High rates of resistance against gatifloxacin, moxifloxacin, erythromycin and clindamycin were observed in the PCR-ribotype 018 isolates. Interestingly, all trf isolates were toxin A-negative, toxin B-positive, but they did not correspond to PCR-ribotype 017, thus being assigned a new ribotype (PCR-ribotype 369). In conclusion, PCR-ribotypes 018 (smz) and 369 (trf) were identified as major circulating strains in both outbreak and non-outbreak settings in Japan. Given their epidemiological relevance, molecular investigations are warranted to clarify potential evolutionary links with related strains found elsewhere, such as PCR-ribotypes 018 and 017 from Europe and North America.

Validation of a phage-open reading frame typing kit for rapid identification of methicillin-resistant Staphylococcus aureus (MRSA) transmission in a tertiary hospital.

Surveillance is very important to prevent the nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA), and infection sources and routes have historically been identified using molecular and epidemiological genotyping with pulsed-field gel electrophoresis. However, phage-open reading frame typing (POT) has recently been developed. Here, we investigated whether POT would be useful to survey MRSA outbreaks and transmission. We therefore applied POT to 91 MRSA isolates detected in cultures from inpatients at our hospital between May and October 2014. Among the 91 isolates, 12 POT types comprising 38 isolated MRSA strains were considered as overlapping. Five of them were detected in different wards, whereas the remaining seven were found in the same ward, including the emergency department. Three of seven POT number 93-155-111 strains were detected in the surgical ward, and all of four POT number 93-157-61 strains were detected in the cardiosurgical ward. These data suggested that transmission of the MRSA strains with the same POT-types from the same wards was nosocomial, and that POT accurately and rapidly identified MRSA strains, which allowed effective control of infection and transmission.

Invasive pulmonary aspergillosis due to Aspergillus lentulus: Successful treatment of a liver transplant patient.

We report a patient with severe invasive pulmonary fungal infection caused by Aspergilllus lentulus, which was identified by genetic analysis, following liver transplantation. The patient was initially suspected to have Aspergilllus fumigatus infection, but worsened clinically despite antifungal therapy appropriate for that species. The patient survived after accurate diagnosis, and detailed drug susceptibility testing led to adequate therapy, demonstrating the importance of performing these investigations for severely immunocompromised patients, including organ transplant recipients.

In vitro evaluations of topical agents to treat Acanthamoeba keratitis.

PURPOSE: To evaluate the effectiveness of topical agents for the treatment of Acanthamoeba keratitis (AK). DESIGN: Laboratory research. PARTICIPANTS: Fifty-six Acanthamoeba isolates from 56 patients with clinically proven AK were studied. METHODS: The effectiveness of 7 agents against Acanthamoeba cysts was determined in vitro. The agents were 1.0% povidone-iodine, 0.05% benzalkonium chloride (BZC), 0.02% chlorhexidine gluconate (CHG), 0.1% propamidine isethionate, 0.02% polyhexamethylene biguanide (PHMB), 5.0% natamycin, and 1.0% voriconazole (VRCZ). These concentrations are those recommended for patients. In addition, 10-fold dilutions of each of the agents were tested. After exposing the cysts to each agent at 35°C for 1 hour or 24 hours, the agents were removed by centrifugal washing. The exposed cysts were observed by optical microscopy for 7 days. In addition, the fine structures of the exposed isolates were examined by transmission electron microscopy (TEM). The genotype of the isolates was determined by 18S rDNA fragment sequencing. MAIN OUTCOME MEASURES: The in vitro susceptibility was determined by complete growth inhibition, and the morphologic appearance was determined by TEM. The genotypes of the 56 isolates were determined by 18S rDNA fragment sequencing. RESULTS: The Acanthamoeba cysts were most susceptible to natamycin, followed by povidone-iodine, BZC, PHMB, propamidine, and CHG. None of the strains was susceptible to VRCZ. The susceptibilities to PHMB and CHG may be time dependent and to propamidine may be concentration dependent. Transmission electron microscopy showed changes in the inner structure of the cysts exposed to natamycin and povidone-iodine. The Acanthamoeba genotype was T4 in 52 isolates, and cysts with the same genotype had different agent susceptibilities. CONCLUSIONS: Natamycin and povidone-iodine had excellent cysti-static (or cystcidal) effects, and PHMB and propamidine did not. There was no correlation between agent effectiveness and Acanthamoeba genotype. Therefore, susceptibility tests of isolates are needed to choose the most appropriate agent, and our results can be a guideline for choosing the most appropriate agent for immediate empirical treatment of AK.

Susceptibility of various oral antibacterial agents against extended spectrum ß-lactamase producing Escherichia coli and Klebsiella pneumoniae.

With the increase in extended spectrum ß-lactamase (ESBL)-producing bacteria in the community, cases are often seen in which treatment of infectious diseases with oral antimicrobial agents is difficult. Therefore, we measured the antimicrobial activities of 14 currently available oral antimicrobial agents against ESBL-producing Escherichia coli and Klebsiella pneumoniae. Based on the standard of the Clinical and Laboratory Standards Institute (CLSI), E. coli showed high susceptibility rates of 99.4% to faropenem (FRPM). In terms of fluoroquinolones, the susceptibility rate of E. coli to levofloxacin (LVFX) was low at 32.2%, whereas it showed a good susceptibility rate of 93.1% to sitafloxacin (STFX). With respect to other antimicrobial agents, susceptibility rates to fosfomycin (FOM) and colistin (CL) were more than 90% each, whereas rates of the two antimicrobial agents expected as therapeutic agents, minocycline (MINO) and sulfamethoxazole-trimethoprim (ST), were low at 62.4% and 44.3%, respectively. Based on the CLSI standard, K. pneumoniae showed high susceptibility rates to ceftibuten (CETB) (91.89%), LVFX (86.49%), and STFX (94.6%), indicating that K. pneumoniae showed higher rates than those of E. coli, particularly to fluoroquinolones. Comparison of susceptibility rates according to E. coli genotype showed that many antimicrobial agents existed to which the CTX-M-9 group showed high susceptibility rates. However, there were many agents to which the CTX-M-1 group showed low susceptibility rates, particularly to CETB (51.1%) and LVFX (17.0%). Although there was no significant difference by genotype between FRPM, STFX, and FOM, a significant difference was observed between LVFX, MINO, and ST. Antibiotic-resistant bacteria with highly pathogenic strains have spread in the community, appropriate use of oral antimicrobial agents is required.