Towards an optimal luteal support modality in agonist triggered cycles: a randomized clinical trial

STUDY QUESTION

In ICSI patients with high risk of ovarian hyperstimulation syndrome (OHSS), are antagonist cycles triggered by gonadotropin releasing hormone (GNRH) agonist with a specialized luteal support regimen associated with comparable ongoing pregnancy rate (OPR) and less OHSS than those triggered by hCG?

SUMMARY ANSWER

In antagonist ICSI cycles, GnRH agonist triggering with a specialized luteal support regimen is associated with comparable OPR to those triggered by hCG but may be less likely to be associated with OHSS.

WHAT IS KNOWN ALREADY

In IVF/ICSI protocols, exogenous hCG was used for years as a substitute of the endogenous LH surge. However, because of its longer half life, hCG is associated with more risk of OHSS, especially in high risk women. For this reason, GnRH agonist triggering was introduced. There is, however, no consensus on the best protocol for luteal support on agonist triggered cycles.

STUDY DESIGN, SIZE, DURATION

Randomized controlled open label trial including 190 participants recruited from June 2015 to March 2016 in a private fertility center. Participants were divided into 2 equal groups; GnRH agonist trigger and hCG trigger. Randomization was done using identical sealed envelope technique.

PARTICIPANTS/MATERIALS, SETTING, METHODS

One hundred ninety women, predicted to have high response, were randomized on the day of final oocyte maturation into two equal groups: group (A), GnRH agonist trigger followed by specialized regimen (1500 IU hCG) at time of oocyte retrieval plus oral estradiol and intramuscular progesterone during luteal phase; and group (B), 5000 IU of hCG with luteal support (oral estradiol and vaginal progesterone).

MAIN RESULTS AND THE ROLE OF CHANCE

The 2 groups were comparable in baseline characteristics. OPR per randomized patient was comparable in the 2 groups {49/95 (51.6%) in group A, and 50/95 (52.6%) in group B ((P = 0.88); RR = 0.980, 95% CI: 0.75-1.29)}. Considerable (moderate + severe) OHSS was higher in group B (13/95 [14%] versus 5/95 [5%] P = 0.047; uncorrected Chi-square test). Upon performing multivariate regression analysis for predicting OHSS, number of follicles ≥11 mm on trigger day was the only independent predictor (P = 0.0004).

LIMITATIONS, REASONS FOR CAUTION

Strict selection criteria limit generalization of results. The study was powered for pregnancy rate not OHSS, so that the strength of evidence on OHSS prediction is weak.

WIDER IMPLICATIONS OF THE FINDINGS

We recommend the use of GnRH agonist plus the specialized luteal phase support in high responders with high risk of OHSS undergoing IVF/ICSI cycles. This protocol achieved a similar ongoing pregnancy to hCG triggering and may be less likely to result in moderate to severe OHSS.

STUDY FUNDING/COMPETING INTEREST(S)

None.

TRIAL REGISTRATION NUMBER

PACTR 201506001132105.

TRIAL REGISTRATION DATE

24/6/2015.

DATE OF FIRST PATIENT’S ENROLLMENT

26/6/2015.

An integron cassette carrying dfr1 with 90-bp repeat sequences located on the chromosome of trimethoprim-resistant isolates of Campylobacter jejuni

The frequent occurrence of high-level trimethoprim resistance in clinical isolates of Campylobacter jejuni was shown to be related to the acquisition of foreign resistance genes (dfrl or dfr9 or both) coding for resistant variants of the enzyme dihydrofolate reductase, the target of trimethoprim. The dfr1 gene detected on the chromosome of 40 different clinical strains of C. jejuni was studied further regarding structure and genetic organization. Most of the dfr1 genes were found as integron cassettes inserted in the chromosome. In 36% of the examined isolated, the dfr1 gene showed identity to that previously characterized in trimethoprim-resistant Escherichia coli. In 40% of the cases, however, a variant of the dfr1 gene containing a 90-bp direct repeat was detected, and in 5% of the isolates, the repeat-containing dfr1 variant was found to occur in the form of two cassettes in tandem in an integron context. The existence of the 90-bp repeat within the coding sequence of the dfr1gene was found to play a role in the adaptation of C. jejuni to ambient concentrations of trimethoprim.

Sulfonamide resistance in clinical isolates of Campylobacter jejuni: mutational changes in the chromosomal dihydropteroate synthase

The characterization of the genetic basis of sulfonamide resistance in Campylobacter jejuni was attempted. The resistance determinant from a sulfonamide-resistant strain of C. jejuni was cloned and was found to show 42% identity with the folP gene (which codes for dihydropteroate synthase, the target of sulfonamides) of the related bacterium Helicobacter pylori. The sequences of the areas surrounding the folP gene in C. jejuni showed similarity to those of the areas surrounding the corresponding gene in H. pylori. The folP gene of C. jejuni, which mediates the resistance, was observed to show particular features when it was compared to other known folP genes. One of these features is the presence of two pairs of direct repeats (15 and 27 bp) within the coding sequence of the gene. Comparison of the C. jejuni folP genes that mediate susceptibility and resistance revealed the occurrence of mutations that changed four amino acid residues. Resistance of C. jejuni to sulfonamides could be associated with one or several of these four mutational substitutions, which all occurred in the five different resistant isolates studied. The codon for one of these changed amino acids was found to be located in the second direct repeat within the coding sequence of the gene. The change made the repeat perfect. The transformation of both the resistance and the susceptibility variants of the gene into an Escherichia coli folP knockout mutant was found to complement the dihydropteroate synthase deficiency, confirming that the characterized sulfonamide resistance determinant codes for the C. jejuni dihydropteroate synthase enzyme. Kinetic measurements established different affinities of sulfonamide for the dihydropteroate synthase enzyme isolated from the resistant and susceptible strains. In conclusion, sulfonamide resistance in C. jejuni was shown to be associated with mutational changes in the chromosomally located gene for dihydropteroate synthase, the target of sulfonamides.

High-level resistance to trimethoprim in clinical isolates of Campylobacter jejuni by acquisition of foreign genes (dfr1 and dfr9) expressing drug-insensitive dihydrofolate reductases

The pathogenic bacterium Campylobacter jejuni has been regarded as endogenously resistant to trimethoprim. The genetic basis of this resistance was characterized in two collections of clinical isolates of C. jejuni obtained from two different parts of Sweden. The majority of these isolates were found to carry foreign dfr genes coding for resistant variants of the dihydrofolate reductase enzyme, the target of trimethoprim. The resistance genes, found on the chromosome, were dfr1 and dfr9. In about 10% of the strains, the dfr1 and dfr9 genes occurred simultaneously. About 10% of the examined isolates were found to be negative for these dfr genes and showed a markedly lower trimethoprim resistance level than the other isolates. The dfr9 and dfr1 genes were located in the context of remnants of a transposon and an integron, respectively. Two different surroundings for the dfr9 gene were characterized. One was identical to the right-hand end of the transposon Tn5393, and in the other, the dfr9 gene was flanked by only a few nucleotides of a Tn5393 sequence. The insertion of the dfr9 gene into the C. jejuni chromosome could have been mediated by Tn5393. The frequent occurrence of high-level trimethoprim resistance in clinical isolates of C. jejuni could be related to the heavy exposure of food animals to antibacterial drugs, which could lead to the acquisition of foreign resistance genes in naturally transformable strains of C. jejuni.

Rapid emergence of high-level resistance to quinolones in Campylobacter jejuni associated with mutational changes in gyrA and parC

Quinolone resistance in clinical isolates of Campylobacter jejuni in Sweden increased more than 20-fold at the beginning of the 1990s. Resistance to 125 microgram of ciprofloxacin per ml in clinical isolates was associated with chromosomal mutations in C. jejuni leading to a Thr-86-Ile substitution in the gyrA product and a Arg-139-Gln substitution in the parC product.

Macrolide resistance in Helicobacter pylori: mechanism and stability in strains from clarithromycin-treated patients

Helicobacter pylori strains from seven patients treated with clarithromycin were investigated for development, mechanism, and stability of resistance. Genetic relatedness between pre- and posttreatment isolates was shown by arbitrary primed PCR. Clarithromycin resistance was associated with A-to-G transitions at either position 2143 or 2144 or at both positions 2116 and 2142. In four cases, the mutations were homozygous. The Cla(r) phenotype was stable after 50 subcultivations in vitro. No erythromycin-modifying enzymes or rRNA methylases were found by biological assays, PCR and sequencing, or cloning methods.