Genomic epidemiology of Staphylococcus aureus isolated from bloodstream infections in South America during 2019 supports regional surveillance.

Staphylococcus aureus remains one of the leading causes of infections worldwide and a common cause of bacteraemia. However, studies documenting the epidemiology of S. aureus in South America using genomics are scarce. We hereby report on the largest genomic epidemiology study to date of both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) in South America, conducted by the StaphNET-SA network. We characterised 404 genomes recovered from a prospective observational study of S. aureus bacteraemia in 58 hospitals from Argentina, Bolivia, Brazil, Paraguay and Uruguay between April and October 2019. We show that a minority of S. aureus isolates are phenotypically multi-drug resistant (5.2%), but more than a quarter are resistant to macrolide-lincosamide-streptogramin B (MLSb). MSSA were more genetically diverse than MRSA. Lower rates of associated antimicrobial resistance in community-associated(CA)-MRSA versus hospital-associated (HA)-MRSA were found in association with three S. aureus genotypes dominating the MRSA population: CC30-MRSA-IVc-t019-lukS/F-PV+, CC5-MRSA-IV-t002-lukS/F-PV- and CC8-MRSA-IVc-t008-lukS/F-PV+-COMER+. These are historically from a CA origin, carry on average fewer antimicrobial resistance determinants, and often lack key virulence genes. Surprisingly, CC398-MSSA-t1451-lukS/F-PV- related to the CC398 human-associated lineage is widely disseminated throughout the region, and is described here for the first time as the most prevalent MSSA lineage in South America. Moreover, CC398 strains carrying ermT (largely responsible for the MLSb resistance rates of MSSA strains: inducible iMLSb phenotype) and sh_fabI (related to triclosan resistance) were recovered from both CA and HA origin. The frequency of MRSA and MSSA lineages differed between countries but the most prevalent S. aureus genotypes are high-risk clones widely distributed in the South American region without a clear country-specific phylogeographical structure. Therefore, our findings underline the need for continuous genomic surveillance by regional networks such as StaphNET-SA. This article contains data hosted by Microreact.

Milk let-down in goats can be influenced by the type of stimuli applied or to which goats are exposed during suckling and hand milking.

The present experiments on goats were conducted with the aim of verifying (a) whether the identity of the goat kids can affect the characteristics of milk let-down during suckling (Study 1) and (b) whether the presence of the goat kids may improve the milk let-down during hand milking (Study 2). In Study 1, 16 lactating goats with twins and 12 with single kids were used. Dams with single goat kids ejected more milk when suckling their kids at Days 5 and 20 of lactation, than when suckling aliens. Dams with twins ejected more milk when suckling their own kids than aliens only at Day 5 of lactation. Taking into account all the dams, they ejected more milk with more fat, protein, and lactose during suckling their own litter than when suckling aliens. In Study 2, when dams (n = 13) were hand milked in the presence of their own litter or in its absence, they ejected more milk with more fat, protein, and lactose than when milked in the presence of alien kids. We conclude that milk let-down in goats can be influenced by the type of stimuli applied or to which they are exposed to during suckling and milking.

Previous sexual experience does not improve estrous behavior and ovulatory activity in seasonally anestrous goats in contact with photostimulated bucks

Sexually inexperienced ewes display lower estrous behavior during the first contact with rams. The objective of this study was to determine whether sexually inexperienced anestrous females display estrous behavior and ovulatory activity as the sexually experienced females, and with restricted sexual experience exposed to photo-stimulated bucks. Six bucks were rendered sexually active during the non-breeding season by exposure to artificially long days (16 h of light and 8 h of darkness per day) for 2.5 months. The first group, sexually experienced females (n = 10) had physical contact with two vasectomized bucks, and mating was allowed; the second group, with restricted sexual experience (n = 10) had contact with two vasectomized bucks through a wire-mesh fence and mating was prevented; the third group, sexually inexperienced females (n = 9) was totally isolated from bucks. At 14-month-old the females were exposed to photostimulated bucks for 15 days. The proportion of females that displayed estrous behavior, ovulations, short and normal ovulatory cycles, and pregnancy rates did not differ between sexually experienced, with restricted sexual experience, and sexually inexperienced (P > 0.05, in all variables). Similarly, the ovulation rate did not differ between the three groups of females (P > 0.05). However, the interval from introduction of the bucks to the first estrus was shorter in sexually inexperienced females (P < 0.05). Therefore, sexually inexperienced anestrous females displayed estrous behavior, ovulation, and pregnancy rate similar to those displayed by sexually experienced and with restricted sexual experience when exposed to photo-stimulated bucks through the male effect.

Previous sexual experience does not improve estrous behavior and ovulatory activity in seasonally anestrous goats in contact with photostimulated bucks

Sexually inexperienced ewes display lower estrous behavior during the first contact with rams. The objective of this study was to determine whether sexually inexperienced anestrous females display estrous behavior and ovulatory activity as the sexually experienced females, and with restricted sexual experience exposed to photo-stimulated bucks. Six bucks were rendered sexually active during the non-breeding season by exposure to artificially long days (16 h of light and 8 h of darkness per day) for 2.5 months. The first group, sexually experienced females (n = 10) had physical contact with two vasectomized bucks, and mating was allowed; the second group, with restricted sexual experience (n = 10) had contact with two vasectomized bucks through a wire-mesh fence and mating was prevented; the third group, sexually inexperienced females (n = 9) was totally isolated from bucks. At 14-month-old the females were exposed to photostimulated bucks for 15 days. The proportion of females that displayed estrous behavior, ovulations, short and normal ovulatory cycles, and pregnancy rates did not differ between sexually experienced, with restricted sexual experience, and sexually inexperienced (P > 0.05, in all variables). Similarly, the ovulation rate did not differ between the three groups of females (P > 0.05). However, the interval from introduction of the bucks to the first estrus was shorter in sexually inexperienced females (P < 0.05). Therefore, sexually inexperienced anestrous females displayed estrous behavior, ovulation, and pregnancy rate similar to those displayed by sexually experienced and with restricted sexual experience when exposed to photo-stimulated bucks through the male effect.(AU)

In dual-purpose subtropical goats, 1 h of extra-light given from 16 to 17 h after dawn (pulse of light) in winter stimulates milk yield.

This research communication addresses the hypothesis that in dual-purpose goats, exposure to 1 h of extra-light given from 16 to 17 h after dawn (pulse of light) in winter stimulates milk yield. One group of goats was maintained under natural short photoperiod (natural day; ND (n = 7)). Another group of lactating females was submitted to an artificial long-day photoperiod consisting of 16 h light and 8 h darkness (long days; LD (n = 7)). A third group of females received one single hour of extra-light 16 h after the fixed dawn (pulse of light; PL (n = 6)). Goats from LD and PL yielded 30% more milk than goats from ND. Mean percentages of fat, protein and lactose contents in milk did not differ between the 3 groups at any stage of lactation, but these components in grams/day were higher in goats from PL than in the others two groups within the first 45 d of lactation. In conclusion, dual-purpose lactating goats that started their lactation during natural short days, the daily exposition to a 1-h pulse of light is sufficient to stimulate milk yield compared to females maintained under natural short photoperiod.

Sexually inexperienced anestrous goats are able to exhibit sexual behaviours exposed to sexually active bucks

The aim of this study was to determine whether sexually inexperienced females could display proceptivity and receptivity behaviours as the experienced, in the first exposure to males. Three groups of females (n=9 each) were used: i) sexually inexperienced, ii) with complete sexual experience, and iii) with limited sexual experience. Three male goats were subjected to photoperiodic treatment for 2.5 months of long days to stimulate their sexual activity during the natural sexual rest (March-April). During anestrous season, females were exposed to photo-stimulated males. Sexual behaviours were recorded during the first three days post-introduction of the males into female groups, in two daily periods of 20 min each. Sexually inexperienced females and those with complete sexual experience showed higher tail wagging than those with limited sexual experience (P<0.001). Sexually inexperienced females displayed higher female-female sniffing and emission of urine than those groups with complete and limited sexual experience (P<0.001 and P<0.05, respectively). Females with limited sexual experience displayed higher female-female mounts than those groups inexperienced and with complete sexual experience (P<0.05). In addition, females with complete sexual experience displayed higher female-male sniffing than those groups inexperienced and with limited sexual experience (P<0.001). Receptivity behaviour did not differ between female groups (P>0.05). We concluded that sexually inexperienced anestrous females display proceptivity and receptivity behaviours as those sexually experienced exposed to photo-stimulated males.(AU)

Sexually inexperienced anestrous goats are able to exhibit sexual behaviours exposed to sexually active bucks

The aim of this study was to determine whether sexually inexperienced females could display proceptivity and receptivity behaviours as the experienced, in the first exposure to males. Three groups of females (n=9 each) were used: i) sexually inexperienced, ii) with complete sexual experience, and iii) with limited sexual experience. Three male goats were subjected to photoperiodic treatment for 2.5 months of long days to stimulate their sexual activity during the natural sexual rest (March-April). During anestrous season, females were exposed to photo-stimulated males. Sexual behaviours were recorded during the first three days post-introduction of the males into female groups, in two daily periods of 20 min each. Sexually inexperienced females and those with complete sexual experience showed higher tail wagging than those with limited sexual experience (P0.05). We concluded that sexually inexperienced anestrous females display proceptivity and receptivity behaviours as those sexually experienced exposed to photo-stimulated males.

Male goat vocalizations stimulate the estrous behavior and LH secretion in anestrous goats that have been previously exposed to bucks.

We investigated whether live vocalizations emitted by bucks interacting with anestrous females stimulate secretion of LH, estrous behavior and ovulation in anestrous goats. In experiment 1, bucks rendered sexually active by exposure to long days followed by natural photoperiod were exposed in a light-proof-building to five anestrous females. Buck vocalizations were reproduced through a microphone-amplifier-loudspeaker system to an open pen where one group of goats (n=6) was exposed for 10 days to these live vocalizations. Another group of females (n=6) was isolated from males and vocalizations. The proportion of goats displaying estrous behavior was significantly higher in females exposed to buck vocalizations than in females isolated from males. The proportion of goats that ovulated did not differ between the 2 groups (exposed to males versus isolated). In experiment 2, female goats that either had previous contact with males (n=7), or no previous contact with males (n=7) were exposed to live buck vocalizations, reproduced as described in experiment 1, for 5 days. The number and amplitude of LH pulses did not differ between groups before exposition to buck vocalizations. Five days of exposure to male vocalizations significantly increased LH pulsatility only in females that had previous contact with males, while LH pulse amplitude was not modified. We concluded that live buck vocalizations can stimulate estrous behavior and LH secretion in goats if they have had previous contact with bucks.

Lack of sexual experience does not reduce the responses of LH, estrus or fertility in anestrous goats exposed to sexually active males.

We investigated whether LH secretion, estrous behavior and fertility would differ between sexually inexperienced and experienced anestrous goats exposed to the males. Male goats were rendered sexually active during the reproductive rest season by exposure to 2.5 months of artificial long days. Two groups of anovulatory sexually inexperienced and sexually experienced does were exposed to males during 15 days (n = 20 per group). LH pulsatility was determined every 15 min from 4h before to 8h after introducing males (Day 0). Estrous behavior was recorded twice daily. Pregnancy rates were determined on Day 50. Fertility was determined at parturition. Male sexual behavior was registered on days 1 and 2 during 1h. Before introducing the males, the number of LH pulses did not differ between groups. After introduction of the males, all females increased their LH pulsatility, but the number of pulses did not differ between sexually inexperienced and experienced goats. The proportion of females displaying estrous behavior with a high pregnancy rate and fertility did not differ between inexperienced and experienced goats. The sexual behavior of the males did not differ significantly between those interacting with sexually inexperienced or experienced goats. We conclude that goats can show substantial endocrine and reproductive responses to males, even in the absence of previous sexual experience, when sexually active bucks are used.

Male sexual behavior contributes to the maintenance of high LH pulsatility in anestrous female goats.

The objective of this study was to determine the importance of male sexual behavior in stimulating LH secretion in anovulatory female goats. Two groups of females (n=10 per group) were each exposed to a buck in sexual rest and submitted to natural daylength. In one group, the buck was awake, whereas in the other group, it was sedated to prevent its sexual behavior. Two other groups of goats (n=10 per group) were exposed to sexually active bucks that had been exposed to 2.5 months of long days. In one group, the buck was awake, and in the other group, it was sedated. LH secretion was determined every 15 min from 4 h before introducing the bucks to 8 h after, then every 15 min again from 20 to 24 h after introducing the bucks. The bucks submitted to natural daylength did not stimulate LH secretion (P>0.05), whether they were sedated or not. In contrast, both the awake and the sedated light-treated bucks induced an increase (P<0.05) of LH pulsatility in the first 4 h following their introduction. However, pulsatility remained elevated until 24 h in the females exposed to the light-treated awake buck, whereas in the group with the light-treated sedated buck, pulsatility diminished (P<0.05) after the first 4 h of stimulation by the buck. In conclusion, the sexual behavior of males contributes to the maintenance of a high LH pulsatility up to 24 h after introduction into a group of anovulatory goats.