Novel selective medium for the isolation ofcorynebacterium kroppenstedtiifrom heavily colonised clinical specimens

Abstract

<jats:sec><jats:title>Aims</jats:title><jats:p>Granulomatous mastitis due to <jats:italic>Corynebacterium kroppenstedtii</jats:italic> is an increasingly recognised cause of an indolent and distressing mastitis in non-lactating females. This slow-growing lipophilic organism is not reliably isolated using routine culture methods. A novel selective culture medium (CKSM) is designed to optimise the isolation of this organism from clinical specimens.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>CKSM contains 10% galactose and Tween 80 (10%) to enhance the growth of <jats:italic>C. kroppenstedtii</jats:italic>, fosfomycin (100 µg/mL) to suppress the other bacteria, and differentiate <jats:italic>C. kroppenstedtii</jats:italic> from non-<jats:italic>kroppenstedtii</jats:italic> lipophilic corynebacteria by esculin hydrolysis. The medium was evaluated for its ability to support the growth of <jats:italic>C. kroppenstedtii</jats:italic>, selection and differentiation of <jats:italic>C. kroppenstedtii</jats:italic> from other bacteria in non-sterile clinical specimens.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p><jats:italic>C. kroppenstedtii</jats:italic> grew as 1–2 mm colonies with black halo on CKSM within 72 hours of incubation, compared with barely visible pinpoint colonies on routine blood agars. During the four-month period of evaluation with 8896 respiratory specimens, 103 breast specimens, 1903 female genital tract specimens, 617 newborn surface swabs and 10 011 miscellaneous specimens, 186 <jats:italic>C. kroppenstedtii</jats:italic> were isolated, including 127 (1.4%) respiratory and 59 (0.5%) miscellaneous specimens, 184 of them were found only on CKSM. Besides the three (2.9%) positive breast specimens, 27 (1.4%) high vaginal and endocervical swabs, and 11 (1.8%) surface swabs of newborns were positive for <jats:italic>C. kroppenstedtii</jats:italic>.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>CKSM is a useful addition to routine agar media for the isolation of <jats:italic>C. kroppenstedtii,</jats:italic> and will be helpful for studying the epidemiology and transmission of this unusual <jats:italic>Corynebacterium</jats:italic> causing granulomatous mastitis.</jats:p></jats:sec>

Classification of 27 Corynebacterium kroppenstedtii -Like Isolates Associated with Mastitis in China and Descriptions of C. parakroppenstedtii sp. nov. and C. pseudokroppenstedtii sp. nov

“…On account of the lipophilic nature, the addition of a lipid component, such as Tween80, is often used to improve the culture yield. A medium that contains galactose, Tween 80, and fosfomycin has been specifically designed for the isolation of C. kroppenstedtii ( 20 ). The accurate identification of Corynebacterium species has become more reliable with the availability of MALDI-TOF MS and molecular techniques in the clinical laboratory ( 21 ).…”

Cystic Neutrophilic Granulomatous Mastitis: A Clinicopathological Study With 16s rRNA Sequencing for the Detection of Corynebacteria in Formalin-Fixed Paraffin-Embedded Tissue

“…A novel selective medium for isolation of C kroppenstedtii has recently been developed, which contains galactose and Tween 80 with fosfomycin. 48 The identification of these organisms has improved due to the availability of newer methods like MALDI-TOF and next-generation sequencing technologies like 16s rRNA gene sequencing. 16s rRNA sequencing has been used for accurate identification of Corynebacterium species from pus cultures 1 and some authors have also developed C kroppenstedtii -specific PCR assays.…”

The Myth of Idiopathic Granulomatous Mastitis

“…34 Highly selective agar promote growth and isolation from cases infected with Corynebacterium. 37 The present work has detected that Corynebacterium should be considered as an important prognostic factor for idiopathic granulomatous mastitis [IGM] recurrence. Therefore, meticulous and careful microbiological assessment is recommended for all inflammatory breast lesions suspicious of idiopathic granulomatous mastitis [IGM].…”