Comparison of direct-plating and broth-enrichment culture methods for detection of potential bacterial pathogens in respiratory secretions

Occurrence of "under-the-radar" antibiotic resistance in anthropogenically affected produce

With global climate change, treated-wastewater irrigation and manure amendment are becoming increasingly important in sustainable agriculture in water- and nutrient-stressed regions. Yet, these practices can potentially disseminate pathogens and antimicrobial resistance determinants to crops, resulting in serious health risks to humans through the food chain. Previous studies demonstrated that pathogen and antimicrobial resistance indicators from wastewater and manure survive poorly in the environment, suggesting that ecological barriers prevent their dissemination. However, we recently found that these elements can persist below detection levels in low quality treated wastewater-irrigated soil, and potentially proliferate under favorable conditions. This "under-the-radar" phenomenon was further investigated here, in treated wastewater-irrigated and poultry litter-amended lettuce plants, using an enrichment platform that resembles gut conditions, and an analytical approach that combined molecular and cultivation-based techniques. Enrichment uncovered clinically relevant multidrug-resistant pathogen indicators and a myriad of antibiotic resistance genes in the litter amended and treated wastewater-irrigated lettuce that were not detected by direct analyses, or in the enriched freshwater irrigated samples. Selected resistant E. coli isolates were capable of horizontally transferring plasmids carrying multiple resistance genes to a susceptible strain. Overall, our study underlines the hidden risks of under-the-radar pathogen and antimicrobial resistance determinants in anthropogenically affected agroenvironments, providing a platform to improve quantitative microbial risk assessment models in the future.

Electrostatic microfiltration (EM) enriches and recovers viable microorganisms at low-abundance in large-volume samples and enhances downstream detection

Rapid and sensitive detection of pathogens in various samples is crucial for disease diagnosis, environmental surveillance, as well as food and water safety monitoring. However, the low abundance of pathogens (<10 CFU) in large volume (1 mL-1 L) samples containing vast backgrounds critically limits the sensitivity of even the most advanced techniques, such as digital PCR. Therefore, there is a critical need for sample preparation that can enrich low-abundance pathogens from complex and large-volume samples. This study develops an efficient electrostatic microfiltration (EM)-based sample preparation technique capable of processing ultra-large-volume (≥500 mL) samples at high throughput (≥10 mL min-1). This approach achieves a significant enrichment (>8000×) of extremely-low-abundance pathogens (down to level of 0.02 CFU mL-1, i.e., 10 CFU in 500 mL). Furthermore, EM-enabled sample preparation facilitates digital amplification techniques sensitively detecting broad pathogens, including bacteria, fungi, and viruses from various samples, in a rapid (≤3 h) sample-to-result workflow. Notably, the operational ease, portability, and compatibility/integrability with various downstream detection platforms highlight its great potential for widespread applications across diverse settings.

Use of cytobrush for bacteriological and cytological diagnosis of endometritis in mares

Background and Aim

A combined microbial and cytological examination of uterine samples is the main diagnostic method for endometritis in mares. This study aimed to describe a procedure for using the same uterine cytobrush (CB) for both bacteriological and cytological evaluation.

Material and Methods

The procedure consists of rolling the CB onto a sterilized glass slide immediately after collection and before the transfer into a sterile saline solution. In Experiment 1, a comparison between bacteriological results of the cotton swab (CS) and CB or pellet was made in 10 mares; in Experiment 2, bacteriological and cytological results were compared between different processing methods of CB in 28 mares; in other 6 mares, a CB was processed for cytology only, to investigate the reasons for the low cellularity of the pellet.

Results

The agreement between culture results from the CB and CS was evaluated, and a comparison between the cytological data obtained by different processing methods of CB was performed. The perfect agreement between the CB and CS microbiological results was found. The described procedure enables useful diagnostic smears for cytology. Moreover, the seeding of both the tip of CB and the saline solution used for the transport produced accurate bacteriological results.

Conclusion

The protocol described in this study for the use of CB for both cytological and bacteriological analysis could be used for the diagnosis of endometritis. To maximize diagnostic sample quality, cytology slides must be prepared with meticulous care in the field to preserve cellular integrity and minimize artifacts.

Bacterial growth comparison of vaccine and non-vaccine type Streptococcus pneumoniae in different enrichment broths

Broth enrichment is used to enhance pneumococcal carriage detection. Identifying serotypical growth difference during enrichment can prevent detection biases. We discovered, using supplemented Todd-Hewitt broth (0.5% yeast extract) at 4-h incubation and supplemented Brain Heart Infusion broth at 5-h incubation, provide no significant growth difference between vaccine and non-vaccine types.

Pneumococcal Carriage in Burkina Faso After 13-Valent Pneumococcal Conjugate Vaccine Introduction: Results From 2 Cross-sectional Population-Based Surveys

Background

Burkina Faso, a country in Africa’s meningitis belt, introduced 13-valent pneumococcal conjugate vaccine (PCV13) in October 2013, with 3 primary doses given at 8, 12 and 16 weeks of age. To assess whether the new PCV13 program controlled pneumococcal carriage, we evaluated overall and serotype-specific colonization among children and adults during the first 3 years after introduction.

Methods

We conducted 2 population-based, cross-sectional, age-stratified surveys in 2015 and 2017 in the city of Bobo-Dioulasso. We used standardized questionnaires to collect sociodemographic, epidemiologic, and vaccination data. Consenting eligible participants provided nasopharyngeal (all ages) and oropharyngeal (≥5 years only) swab specimens. Swab specimens were plated onto blood agar either directly (2015) or after broth enrichment (2017). Pneumococci were serotyped by conventional multiplex polymerase chain reaction. We assessed vaccine effect by comparing the proportion of vaccine-type (VT) carriage among colonized individuals from a published baseline survey (2008) with each post-PCV survey.

Results

We recruited 992 (2015) and 1005 (2017) participants. Among children aged <5 years, 42.8% (2015) and 74.0% (2017) received ≥2 PCV13 doses. Among pneumococcal carriers aged <1 year, VT carriage declined from 55.8% in 2008 to 36.9% in 2017 (difference, 18.9%; 95% confidence interval, 1.9%–35.9%; P = .03); among carriers aged 1–4 years, VT carriage declined from 55.3% to 31.8% (difference, 23.5%; 6.8%–40.2%; P = .004); and among participants aged ≥5 years, no significant change was observed.

Conclusion

Within 3 years of PCV13 implementation in Burkina Faso, we documented substantial reductions in the percentage of pneumococcal carriers with a VT among children aged <5 years, but not among persons aged ≥5 years. More time, a change in the PCV13 schedule, or both, may be needed to better control pneumococcal carriage in this setting.