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Published on: December 12, 2011
[Bacterial culture of donor semen before and after cryopreservation: A preliminary study]
Ling Wan1, Ling Chen1, Jing Huang1
1Human Sperm Bank, Chongqing Research Institute of Population and Family Planning Science and Technology, Chongqing 400020, China.
Objective:
To investigate the factors causing bacterial contamination of donor semen during cryopreservation.
Methods:
Based on the WHO Laboratory Manual for the Examination and Processing of Human Semen (5th ed), we diluted donor semen samples with sperm cryopreservation medium in a 1∶1 (v/v) ratio. Before the experiment, we cultured bacteria in the sperm cup, sperm cryopreservation medium and Columbia blood a-gar medium to ensure sterile growth. We also conducted bacterial culture of 3,112 semen samples before and after freezing and, according to the number of bacterial colonies (NBC), divided them into a normal group (NBC before freezing <104 cfu/ml and >NBC after freezing) and an abnormal group (NBC before freezing ≥104 cfu/ml and ≥ NBC after freezing, or NBC before freezing < NBC after freezing), followed by bacterial species identification of the suspected colonies.
Results:
Of the 3 112 donor semen samples, 2 458 (78.98%) were included in the normal, and the other 654 (21.02%) in the abnormal group (263 ［8.45%］ with NBC before freezing ≥104 cfu/ml and ≥ NBC after freezing, and 391 ［12.56%］ with NBC before freezing < NBC after freezing). In the suspected colonies, 217 (6.97%) strains of bacteria were isolated and identified, mainly including Staphylococcus epidermidis (23.96%), Staphylococcus haemolyticus (16.59%), Corynebacterium minutissimum (11.52%), Staphylococcus aureus (7.37%), and Enterococcus faecalis (5.99%).
Conclusions:
The bacteria detected in the donor semen mainly included Staphylococcus epidermidis, Staphylococcus haemolyticus, Corynebacterium minutissimum, Staphylococcus aureus and Enterococcus faecalis. Many factors may cause bacterial contamination of donor semen during cryopreservation, which can be reduced by employing sterile, clean and dry materials, appropriate semen preservation methods, normalized experimental environment, and standard operating procedures.
Insights
Bacterial contamination in donor semen during cryopreservation is a significant issue, with common culprits including Staphylococcus epidermidis and Staphylococcus aureus. Implementing sterile techniques and standardized procedures can effectively reduce contamination risks.
Area of Science:
- Reproductive biology
- Microbiology
- Semen cryopreservation
Background:
- Bacterial contamination poses a risk to the integrity of donor semen during cryopreservation.
- Understanding the sources and types of bacteria is crucial for improving semen processing and storage.
Purpose of the Study:
- To identify the factors contributing to bacterial contamination in donor semen during the cryopreservation process.
- To determine the prevalence and types of bacteria found in cryopreserved donor semen.
Main Methods:
- Analysis of 3,112 donor semen samples before and after cryopreservation.
- Bacterial culture and colony counting to categorize samples as normal or abnormal based on bacterial load.
- Identification of bacterial species from contaminated samples.
Main Results:
- 21.02% of samples showed bacterial contamination post-cryopreservation.
- The most prevalent bacteria identified were Staphylococcus epidermidis (23.96%), Staphylococcus haemolyticus (16.59%), Corynebacterium minutissimum (11.52%), Staphylococcus aureus (7.37%), and Enterococcus faecalis (5.99%).
Conclusions:
- Common bacterial contaminants in donor semen include Staphylococcus species, Corynebacterium minutissimum, and Enterococcus faecalis.
- Minimizing contamination requires strict adherence to sterile materials, appropriate preservation techniques, controlled environments, and standardized operating procedures.
