Mycoplasma Contamination of Cel Cultures: Detection and Eradication
Cell culture is a vital component of biological and medical research. It is used in numerous applications
including the investigation of cell physiology, the testing of chemical compounds on specific cel types,
the synthesis of valuable biologicals, and the creation of genetically-modified animals. Contamination of
cell cultures can profoundly affect research results by decreasing cell growth, altering phenotypic and
metabolic characteristics, inhibiting differentiation, and cell death. Mycoplasma sp.
are the most
common contaminants detected in cell cultures (Table 1).
Lactic dehydrogenase elevating virus (LDEV) 1.1 Parvoviruses
Lymphocytic choriomeningitis virus (LCMV)
. Prevalence of cel culture contaminants detected in 19,666
samples submitted to RADIL in 2009.
belong to the class Mollicutes, which includes over 100 species of Mycoplasma
very closely related genus, Acholeplasma
(1). The most prevalent Mycoplasma
contaminants of cultured cells are Mycoplasma orale
, Mycoplasma hyorhinis
, Mycoplasma arginini
, Mycoplasma fermentans, Mycoplasma hominis
and Acholeplasma laidlawi
(2). Infections of cell
cultures with Mycoplasma pulmonis
, the Mycoplasma
species most commonly found in rodents, can
occur, but are extremely rare. Detection
Among bacterial infections, Mycoplasma
contamination poses a particular challenge because it does not conspicuously overgrow the cell culture, can only be detected using special assays, and is resistant to many commonly used antibiotics. Thus, contaminations may be insidious al owing continued undetected propagation of Mycoplasma
, which is then spread to other cultures within the laboratory, and may be further disseminated by interchange of cell lines among laboratories. It is important to
employ rigorous testing to identify Mycoplasma
infected cell lines. Many methods have been used to
detect Mycoplasma sp.
including staining techniques, electron microscopy, biochemical and
immunological tests, and some hybridization assays (3). These methods can be complicated and time
consuming, may only detect a few Mycoplasma
species, have a low sensitivity, be difficult to interpret,
or require specialized equipment. Recently, PCR assays have been developed to detect the presence of Mycoplasma
sp. IDEXX RADIL’s Mycoplasma
assay is highly sensitive, detecting as little as 1-10
organisms, and employs two distinct PCR assays which amplify different regions of the genome. Positive
results with both primers provide a high level of confidence that all lines are infected with Mycoplasama. Diagnostic testing results are available within 5 business days after receipt of samples
at IDEXX RADIL’s secure website. Additional y, an email is sent to the submitter as soon as results are
Samples may be submitted as pellets of cells in growth medium or phosphate buffered saline or vials of
frozen cells with cryoprotectant. The IDEXX RADIL’s assay detects all species of Mycoplasma
infect cell cultures and includes Acholeplasma laidlawi
and Spiroplasma mirum
, two other members of
the Mollicutes class that also can contaminate cultured cells (Table 2).
. Bacteria detected by RADIL’s PCR assay.
contamination of cell cultures adversely affects research. Once detected, it is important to
eradicate the infection to prevent further spread of the contaminant. Many of the antibiotics commonly
used in cell culture are ineffective against Mycoplasma
, but several anti-Mycoplasma
been developed that are available commercially. The infection can be completely eliminated by
autoclaving the infected cultures and replacing them with fresh stocks, however, that is not possible if
the entire cell line has been contaminated or if it is an irreplaceable culture. There are four general
categories of antibiotics that can be used to eliminate contamination (Table 3).
Mode of Action
Effect on bacteria Treatment period
. Antibiotics used in the eradication of Mycoplasma contamination (4).
It is recommended that cells be passaged an additional 3-5 times after treatment in the absence of
antibiotics and then retested for Mycoplasma to ensure that the infection has cleared.
Note: The prophylactic use of anti-Mycoplasma antibiotics is not recommended because it involves
more manipulation of the culture which could compromise sterile technique and the bacteria could
develop resistance to the antibiotic. References
1. Author unknown. “Mycoplasma
: The Insidious Invader of Cell Cultures”. InvivoGen Insight.
InvivoGen, November/December 2005. Web. 9 May 2011.
2. Drexler HG, Uphoff CC. “Mycoplasma contamination of cell cultures: Incidence, sources, effects,
detection, elimination, prevention”. Cytotechnology
3. Drexler HG, Uphoff CC. “Contamination of cell cultures, Mycoplasma.” Encyclopedia of Cel
Eds. E Spier, B Griffiths, AH Scragg. Wiley, New York, 2000. 609-627.
4. Uphoff CC, Meyer C, Drexler HG. “Elimination of mycoplasma from leukemia-lymphoma cell
lines using antibiotics”. Leukemia
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