Analysis of two sequential SARS-CoV-2 outbreaks on a haematology-oncology ward and the role of infection prevention.

Two SARS-CoV-2 nosocomial outbreaks occurred on the haematology ward of our hospital. Patients on the ward were at high risk for severe infection because of their immunocompromised status. Whole Genome Sequencing proved transmission of a particular SARS-CoV-2 variant in each outbreak. The first outbreak (20 patients/31 healthcare workers (HCW)) occurred in November 2020 and was caused by a variant belonging to lineage B.1.221. At that time, there were still uncertainties on mode of transmission of SARS-CoV-2, and vaccines nor therapy were available. Despite HCW wearing II-R masks in all patient contacts and FFP-2 masks during aerosol generating procedures (AGP), the outbreak continued. Therefore, extra measures were introduced. Firstly, regular PCR-screening of asymptomatic patients and HCW; positive patients were isolated and positive HCW were excluded from work as a rule and they were only allowed to resume their work if a follow-up PCR CT-value was ≥30 and were asymptomatic or having only mild symptoms. Secondly, the use of FFP-2 masks was expanded to some long-lasting, close-contact, non-AGPs. After implementing these measures, the incidence of new cases declined gradually. Thirty-seven percent of patients died due to COVID-19. The second outbreak (10 patients/2 HCW) was caused by the highly transmissible omicron BA.1 variant and occurred in February 2022, where transmission occurred on shared rooms despite the extra infection control measures. It was controlled much faster, and the clinical impact was low as the majority of patients was vaccinated; no patients died and symptoms were relatively mild in both patients and HCW.

Chlamydia trachomatis intra-bacterial and total plasmid copy number in clinical urogenital samples.

Chlamydia trachomatis (CT) increases its plasmid numbers when stressed, as occurs in clinical trachoma samples. Most CT tests target the plasmid to increase the test sensitivity, but some only target the chromosome. We investigated clinical urogenital samples for total plasmid copy numbers to assess its diagnostic value and intra-bacterial plasmid copy numbers to assess its natural variation. Both plasmid and chromosome copies were quantified using qPCR, and the plasmid:chromosome ratio (PCr) calculated in two cohorts: (1) 383 urogenital samples for the total PCR (tPCr), and (2) 42 vaginal swabs, with one half treated with propium-monoazide (PMA) to prevent the quantification of extracellular DNA and the other half untreated to allow for both tPCr and intra-bacterial PCr (iPCr) quantification. Mann-Whitney U tests compared PCr between samples, in relation to age and gender. Cohort 1: tPCr varied greatly (1-677, median 16). Median tPCr was significantly higher in urines than vaginal swabs (32 vs. 11, p < 0.001). Cohort 2: iPCr was more stable than tPCr (range 0.1-3 vs. 1-11). To conclude, tPCr in urogenital samples was much more variable than previously described. Transport time and temperature influences DNA degradation, impacting chromosomal DNA more than plasmids and urine more than vaginal samples. Data supports a plasmid target in CT screening assays to increase clinical sensitivity.

Genital and anal Chlamydia trachomatis bacterial load in concurrently infected women: a cross-sectional study.

OBJECTIVES: Most international STI guidelines recommend Chlamydia trachomatis anorectal testing in women after self-reported sexual exposure or symptoms in women. However, it has been shown that the prevalence of anorectal C. trachomatis is as high (7%-17 %) in women who do not report anorectal intercourse (AI) as in women who do. This study assessed the correlation between the genital and anorectal C. trachomatis load in concurrently infected women for increased microbiological insight. METHODS: A convenience sample of 105 women with a concurrent (genital and anorectal) C. trachomatis infection was included from the STI clinic in South Limburg, the Netherlands. Women provided self-collected vaginal and anorectal swabs. The C. trachomatis load was quantified with qPCR and the human cell load was assessed to ensure sample adequacy. Genital and anorectal C. trachomatis loads were divided into tertiles for comparison. The χ2 test and linear regression were used to compare genital and anorectal C. trachomatis loads and identify determinants associated with load. RESULTS: The overall median C. trachomatis load was higher in genital (median 5.3 log10C. trachomatis/ml) than anorectal samples (median 3.4, p ≤ 0.001), but both loads were within the same range. The genital and anal load categories were not related within one woman (p = 0.99), both in women with and without AI. The anorectal C. trachomatis load was in the same or higher load category than the genital load in 56% of women without AI, and 79% of women with AI. CONCLUSIONS: Although no cut-off for clinical relevance is known, an anorectal C. trachomatis load in the same or higher load category than the genital C. trachomatis load is likely to be clinically relevant. Other measurements should also be taken into account, such as leucocytes or bacterial viability to distinguish infection from contamination or exposure.

Natural Course of Chlamydia trachomatis Bacterial Load in the Time Interval between Screening and Treatment in Anogenital Samples.

INTRODUCTION: Although Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection worldwide, little is known about the natural course of the bacterial load during infection. We investigated the natural course of the bacterial load in the interval between screening and returning for treatment in genital and anorectal CT-infections. MATERIALS & METHODS: CT-positive patients, visiting our STI-clinic in the Netherlands from June 2011-January 2014, provided a second urogenital and/or anorectal sample when returning for treatment (diagnostic sample = T1; treatment sample = T2). Patient-record provided data about the days between samples and the date of last unsafe sex. Included patients were ≥18 years old, HIV-negative and did not report antibiotic use in the study-interval. CT load was quantified using qPCR. CT load was log-transformed, and a CT load difference (Δ-CT load) of >1 log was deemed clinically relevant. Chi-square test compared load category distributions over time (decrease/equal/increase), between sample types. RESULTS: 274 patients provided 296 paired samples. Majority of samples had a stable CT load in the interval T1-T2 (66.3%, 73.1% and 48.6% for vaginal swabs, urine and anorectal swabs resp. p = 0.07). Load decreased in 17-41% of patients, while ±10% of patients showed an increase in CT load. No association between Δ-CT load and the interval T1-T2 was observed. Large variations can be seen in CT load at T1 and over time. DISCUSSION: The majority (±90%) of patients have a stable or decreasing CT load in the time interval between screening and returning for treatment. The number of days between sampling was not associated with change in CT load. In the first month after the last unsafe sex, only stable CT loads were seen. Our data seems to indicate that when most patients visit an STI-clinic, recommended 2 weeks after infection, the infection has already been established or is in its downward phase.