P-167 Bacterial contamination of embryo culture medium in conventional in vitro fertilisation versus ICSI
Authors: Berkes-Bara É , Nemes A , Beáta D , Joó K , Murber Á , Urbancsek J , Fancsovits P 
Published: June 2023

Abstract

Study question
Our aim is presenting a clinical case of pregnancy using intracytoplasmatic sperm injection with bacterial contamination of embryo culture after failed conventional in vitro fertilisation.

Summary answer
Intracytoplasmatic sperm injection (ICSI) can be an effective and safe method to prevent embryo culture infection in case of microbial contamination of semen.

What is known already
Contamination of embryo culture is rare, but can be detrimental. The most common sources are semen and follicular fluid. We currently have no standard protocols for monitoring biological fluids. Semen often contains bacteria even if hygiene rules for collection are followed. Most studies found no significant difference in the effectiveness of in vitro fertilisation treatment in the presence or absence of bacteriospermia. This can be explained by sperm preparation techniques, antibiotic content of culture media and use of ICSI. Most centres advise against contaminated embryo transfers, but some achieved pregnancy after removing the zona pellucida or using ICSI.

Study design, size, duration
This is a case report of two consecutive in vitro fertilisation - ICSI cycles at the Division of Assisted Reproduction, Department of Obstetrics and Gynecology, Semmelweis University, Budapest in 2022.

Participants/materials, setting, methods
First we performed conventional in vitro fertilisation in a couple with secondary infertility because of oligoasthenozoospermia. For the second time we suggested ICSI due to bacterial growth observed in the embryo culture medium. Microbiological analyses were carried out. We video-recorded the cytoplasmic infection of one oocyte following ICSI with time-lapse microscopy.

Main results and the role of chance
After conventional in vitro fertilisation we observed a proliferation of rods in the embryo culture medium. The control culture medium was sterile. The semen and infected embryo culture medium contained Escherichia coli and Staphylococcus hominis. The oocytes did not fertilize and degenerated. The husband was asymptomatic and did not have alteration in physical examination therefore he was not treated with antibiotics. In next cycle we performed ICSI. 2 of 14 oocytes fertilized normally and developed into high-quality blastocysts. One embryo was transferred resulting in live birth and one embryo was cryopreserved. We video-documented proliferation of bacteria in one fertilised oocyte but not in the others. Infected oocyte was removed from culture and its culture medium showed Escherichia coli and Cutibacterium acnes. Fungal culture and sexually transmitted diseases were negative. The semen only contained Escherichia coli. The cervix culture was negative. Escherichia coli was resistant to gentamicin contained in culture medium.

Limitations, reasons for caution
We only had one case of bacterial contamination in 30 years and therefore can not conclude to the routine use of ICSI if microbial infections of biological fluids are present.

Wider implications of the findings
ICSI can be offered to patients with bacterial contamination of semen and can help reducing the risk of infection of embryo culture. We can prevent the disadvantages of excessive antibiotic treatments. New guidelines are needed how to handle bacterial contamination of embryo culture media.

Trial registration number
not applicable