Molecular epidemiology, in vitro susceptibility and exoenzyme screening of Malassezia clinical isolates

Introduction. Malassezia folliculitis (MF) and pityriasis versicolor (PV) are common dermatoses caused by Malassezia species. Their molecular epidemiology, drug susceptibility and exoenzymes are rarely reported in China. Aim. To investigate the molecular epidemiology, drug susceptibility and enzymatic profile of Malassezia clinical isolates. Methodology. Malassezia strains were recovered from MF and PV patients and healthy subjects (HS) and identified by sequencing analysis. The minimum inhibitory concentrations (MICs) of nine antifungals (posaconazole, voriconazole, itraconazole, fluconazole, ketoconazole, miconazole, bifonazole, terbinafine and caspofungin) and tacrolimus, the interactions between three antifungals (itraconazole, ketoconazole and terbinafine) and tacrolimus, and the extracellular enzyme profile were evaluated using broth and checkerboard microdilution and the Api-Zym system, respectively. Results. Among 392 Malassezia isolates from 729 subjects (289 MF, 218 PV and 222 HS), Malassezia furfur and Malassezia globosa accounted for 67.86 and 18.88 %, respectively. M. furfur was the major species in MF and PV patients and HS. Among 60M. furfur and 50M. globosa strains, the MICs for itraconazole, posaconazole, voriconazole and ketoconazole were <1 μg ml−1. M. furfur was more susceptible to itraconazole, terbinafine and bifonazole but tolerant to miconazole compared with M. globosa (P<0.05). Synergistic effects between terbinafine and itraconazole or between tacrolimus and itraconazole, ketoconazole or terbinafine occurred in 6, 7, 6 and 9 out of 37 strains, respectively. Phosphatases, lipases and proteases were mainly secreted in 51 isolates. Conclusions. Itraconazole, posaconazole, voriconazole and ketoconazole are theagents against which there is greatest susceptibility. Synergistic effects between terbinafine and itraconazole or tacrolimas and antifungals may be irrelevant to clinical application. Overproduction of lipases could enhance the skin inhabitation of M. furfur.

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Emergence of multidrug-resistantMycobacterium simiae: An in vitro study from a regional tuberculosis reference laboratory in Iran

10.1101/549428 ◽

2019 ◽

Author(s):

Mohammad Javad Nasiri ◽

Sirus Amini ◽

Zahra Nikpor ◽

Samaneh Arefzadeh ◽

Mohammad Mosavi ◽

...

Keyword(s):

Drug Testing ◽

In Vitro Study ◽

Drug Susceptibility ◽

Multidrug Resistant ◽

Drug Susceptibility Testing ◽

Clinical Isolates ◽

Reference Laboratory ◽

In Vitro Susceptibility ◽

Susceptibility Patterns

AbstractIntroductionMycobacterium simiaeis an emerging pathogen in Iran and little is known about drug susceptibility patterns of this pathogen.Materials and methodsTwenty five clinical isolates ofM. simiaefrom 80 patients with confirmed NTM pulmonary disease were included in this study. For drug susceptibility testing (DST), proportional and broth microdilution methods were used according to the clinical and laboratory standards institute (CLSI) guideline.ResultsAll clinical isolates ofM. simiaewere resistant to isoniazid, rifampicin, ethambutol, streptomycin, amikacin, kanamycin, ciprofloxacin and clarithromycin. They also were highly resistant to ofloxacin (80%). Susceptibility to ofloxacin was only noted in the 5 isolates.ConclusionsClinical isolates ofM.simiaewere multidrug resistant, and had different drug susceptibility patterns than previously published studies. DST results can assist in selecting more appropriate treatment regimens. Newer drugs with proven clinical efficacy correlating with in vitro susceptibility should be substituted with first- and second line anti-TB drug testing.

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In vitro susceptibility of clinical isolates ofBacteroides fragilis andBacteroides thetaiotaomicron in Japan

European Journal of Clinical Microbiology & Infectious Diseases ◽

10.1007/bf01967801 ◽

1992 ◽

Vol 11 (11) ◽

pp. 1069-1073 ◽

Cited By ~ 8

Author(s):

K. Watanabe ◽

K. Ueno ◽

N. Kato ◽

Y. Muto ◽

K. Bandoh ◽

...

Keyword(s):

Clinical Isolates ◽

In Vitro Susceptibility

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Molecular Epidemiology and Antifungal Susceptibility of Trichophyton Isolates in Greece: Emergence of Terbinafine-Resistant Trichophytonmentagrophytes Type VIII Locally and Globally

Journal of Fungi ◽

10.3390/jof7060419 ◽

2021 ◽

Vol 7 (6) ◽

pp. 419

Author(s):

Maria Siopi ◽

Ioanna Efstathiou ◽

Konstantinos Theodoropoulos ◽

Spyros Pournaras ◽

Joseph Meletiadis

Keyword(s):

Molecular Epidemiology ◽

Antifungal Susceptibility ◽

Reference Method ◽

Cross Resistance ◽

Squalene Epoxidase ◽

In Vitro Susceptibility ◽

Type Viii ◽

In Vitro Antifungal Susceptibility ◽

Resistance Rates

Trichophyton isolates with reduced susceptibility to antifungals are now increasingly reported worldwide. We therefore studied the molecular epidemiology and the in vitro antifungal susceptibility patterns of Greek Trichophyton isolates over the last 10 years with the newly released EUCAST reference method for dermatophytes. Literature was reviewed to assess the global burden of antifungal resistance in Trichophyton spp. The in vitro susceptibility of 112 Trichophyton spp. molecularly identified clinical isolates (70 T. rubrum, 24 T. mentagrophytes, 12 T. interdigitale and 6 T. tonsurans) was tested against terbinafine, itraconazole, voriconazole and amorolfine (EUCAST E.DEF 11.0). Isolates were genotyped based on the internal transcribed spacer (ITS) sequences and the target gene squalene epoxidase (SQLE) was sequenced for isolates with reduced susceptibility to terbinafine. All T. rubrum, T. interdigitale and T. tonsurans isolates were classified as wild-type (WT) to all antifungals, whereas 9/24 (37.5%) T. mentagrophytes strains displayed elevated terbinafine MICs (0.25–8 mg/L) but not to azoles and amorolfine. All T. interdigitale isolates belonged to ITS Type II, while T. mentagrophytes isolates belonged to ITS Type III* (n = 11), VIII (n = 9) and VII (n = 4). All non-WT T. mentagrophytes isolates belonged to Indian Genotype VIII and harbored Leu393Ser (n = 5) and Phe397Leu (n = 4) SQLE mutations. Terbinafine resistance rates ranged globally from 0–44% for T. rubrum and 0–76% for T. interdigitale/T. mentagrophytes with strong endemicity. High incidence (37.5%) of terbinafine non-WT T. mentagrophytes isolates (all belonging to ITS Type VIII) without cross-resistance to other antifungals was found for the first time in Greece. This finding must alarm for susceptibility testing of dermatophytes at a local scale particularly in non-responding dermatophytoses.

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In Vitro Activities of Daptomycin against 2,789 Clinical Isolates from 11 North American Medical Centers

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.45.6.1919-1922.2001 ◽

2001 ◽

Vol 45 (6) ◽

pp. 1919-1922 ◽

Cited By ~ 115

Author(s):

Arthur L. Barry ◽

Peter C. Fuchs ◽

Steven D. Brown

Keyword(s):

Clinical Isolates ◽

In Vitro Activity ◽

Broth Microdilution ◽

In Vitro Susceptibility ◽

Medical Centers ◽

Mueller Hinton ◽

Calcium Cations ◽

Important Exception ◽

Mueller Hinton Broth

ABSTRACT The in vitro activity of daptomycin is affected by the concentration of calcium cations in the test medium. Mueller-Hinton broth is currently adjusted to contain 10 to 12.5 mg of magnesium per liter and 20 to 25 mg of calcium per liter, but for testing of daptomycin, greater concentrations of calcium (50 mg/liter) are recommended to better resemble the normal concentration of ionized calcium in human serum. Two levels of calcium were used for broth microdilution tests of 2,789 recent clinical isolates of gram-positive bacterial pathogens. MICs of daptomycin were two- to fourfold lower when the broth contained additional calcium. For most species, however, the percentages of strains that were inhibited by 2.0 μg of daptomycin per ml were essentially identical with the two broth media. Enterococci were the important exception; i.e., 92% were inhibited when tested in calcium-supplemented broth but only 35% were inhibited by 2.0 μg/ml without the additional calcium. This type of information should be considered when selecting criteria for defining in vitro susceptibility to daptomycin.

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In vitro susceptibility of Mycoplasma hominis clinical isolates to tetracyclines, quinolones and macrolides

Diagnostic Microbiology and Infectious Disease ◽

10.1016/s0732-8893(02)00459-5 ◽

2002 ◽

Vol 44 (4) ◽

pp. 359-361 ◽

Cited By ~ 17

Author(s):

Zmira Samra ◽

Shoshana Rosenberg ◽

Yigal Soffer

Keyword(s):

Mycoplasma Hominis ◽

Clinical Isolates ◽

In Vitro Susceptibility

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Impact of susceptibility to injectable antibiotics on the treatment outcomes of Mycobacterium abscessus pulmonary disease

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab215 ◽

2021 ◽

Author(s):

Youngmok Park ◽

Yea Eun Park ◽

Byung Woo Jhun ◽

Jimyung Park ◽

Nakwon Kwak ◽

...

Keyword(s):

Treatment Outcomes ◽

Pulmonary Disease ◽

Drug Susceptibility ◽

Mycobacterium Abscessus ◽

Beta Lactams ◽

In Vitro Susceptibility ◽

Referral Hospitals ◽

Microbiological Cure ◽

Culture Conversion

Abstract Objectives Current guidelines recommend a susceptibility-based regimen for Mycobacterium abscessus subspecies abscessus pulmonary disease (MAB-PD), but the evidence is weak. We aimed to investigate the association between treatment outcomes and in vitro drug susceptibility to injectable antibiotics in MAB-PD patients. Methods We enrolled MAB-PD patients treated with intravenous amikacin and beta-lactams for ≥4 weeks at four referral hospitals in Seoul, South Korea. Culture conversion and microbiological cure at one year were evaluated based on susceptibility to injectable antibiotics among patients treated with those antibiotics for ≥ 2 weeks. Results A total of 82 patients were analysed. The mean age was 58.7 years, and 65.9% were women. Sputum culture conversion and microbiological cure were achieved in 52.4% and 41.5% of patients, respectively. Amikacin was the most common agent to which the M. abscessus subspecies abscessus isolates were susceptible (81.7%); 9.8% and 24.0% of the isolates were resistant to cefoxitin and imipenem, respectively. The clarithromycin-inducible resistance (IR) group (n = 65) had a lower microbiological cure rate than the clarithromycin-susceptible group (35.4% vs. 64.7%). The treatment outcomes appeared to be similar regardless of in vitro susceptibility results with regard to intravenous amikacin, cefoxitin, imipenem, and moxifloxacin. In the subgroup analysis of the clarithromycin-IR group, the treatment outcomes did not differ according to antibiotic susceptibility. Conclusions We did not find evidence supporting the use of susceptibility-based treatment with intravenous amikacin and beta-lactams in patients with MAB-PD. Further research would be required.

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1593. Antimicrobial Activity of Ceftazidime-Avibactam and Comparator Agents Against OXA-48 β-lactamase–Producing Enterobacterales Collected in International Medical Centers, Including the United States, in 2017–2018

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.1773 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S793-S793

Author(s):

Lynn-Yao Lin ◽

Dmitri Debabov ◽

William Chang

Keyword(s):

Antimicrobial Agents ◽

The United States ◽

Resistance Mechanisms ◽

Clinical Isolates ◽

Surveillance Program ◽

Multiple Resistance ◽

In Vitro Susceptibility ◽

Medical Centers ◽

Custom Made

Abstract Background OXA-48 is a carbapenemase with low-level hydrolytic activity toward cephalosporins. This study evaluated in vitro activities of ceftazidime-avibactam (CAZ-AVI), meropenem (MEM), meropenem-vaborbactam (MVB), ceftolozane-tazobactam (C/T), and other antimicrobial agents against 113 OXA-48-producing Enterobacterales with multiple resistance mechanisms collected in a 2017–2018 global surveillance program. Methods Nonduplicate clinical isolates of 113 Enterobacterales were collected from medical centers in 25 countries in 2017–2018. In vitro susceptibility tests were performed by broth microdilution with a custom-made panel consisting of CAZ-AVI, ceftazidime (CAZ), MEM, MVB, C/T, colistin (COL), gentamicin (GEN), levofloxacin (LEV), and amikacin (AMK). Whole genome sequencing or quantitative PCR data were used to analyze resistance mechanisms, such as OXA-48, extended-spectrum β-lactamase (ESBL), original-spectrum β-lactamase (OSBL), and AmpC β-lactamase. Clinical and Laboratory Standards Institute breakpoints were applied for susceptibility interpretations. Results Of 113 OXA-48–producing clinical isolates, 20 carried OXA-48 alone. The remaining 93 isolates carried additional β-lactamases, including 63 with ESBL (CTX-M-15) + OSBL (SHV, TEM), 15 with AmpC (DHA, AAC, CMY) + ESBL (CTX-M-15), and 15 with OSBL (SHV, TEM). 99.1% (all but 1) of all isolates tested were susceptible to CAZ-AVI, whereas 71.7%, 17.7%, and 14.2% were susceptible to MVB, MEM, and C/T, respectively. Among isolates harboring multiple resistance mechanisms (OXA-48 + ESBL + OSBL; n=63), 98.4%, 69.8%, 11.1%, and 7.9% were susceptible to CAZ-AVI, MVB, MEM, and C/T, respectively. Among isolates carrying OXA-48 + AmpC + ESBL + OSBL (n=15), 100%, 66.7%, 13.3%, and 13.3% were susceptible to CAZ-AVI, MVB, MEM, and C/T, respectively (Table). Aminoglycosides (AMK and GEN) and other β-lactams (eg, CAZ) were 20%–90% active against these isolates. COL was the second most effective comparator, inhibiting 83.2% of these isolates. Table Conclusion CAZ-AVI was the most effective agent in this study compared with other antibiotics, including β-lactams, β-lactam–β-lactamase inhibitor combinations, aminoglycosides, and COL, against OXA-48-producing Enterobacterales carrying multiple β-lactamases. Disclosures Lynn-Yao Lin, MS, AbbVie (Employee) Dmitri Debabov, PhD, AbbVie (Employee) William Chang, BS, AbbVie (Employee)

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