Short-term associations between Legionnaires' disease incidence and meteorological variables in Belgium, 2011-2019.

The number of reported cases with Legionnaires' disease (LD) is increasing in Belgium. Previous studies have investigated the associations between LD incidence and meteorological factors, but the Belgian data remained unexplored. We investigated data collected between 2011 and 2019. Daily exposure data on temperature, relative humidity, precipitation and wind speed was obtained from the Royal Meteorological Institute for 29 weather stations. Case data were collected from the national reference centre and through mandatory notification. Daily case and exposure data were aggregated by province. We conducted a time-stratified case-crossover study. The 'at risk' period was defined as 10 to 2 days prior to disease onset. The corresponding days in the other study years were selected as referents. We fitted separate conditional Poisson models for each day in the 'at risk' period and a distributed lag non-linear model (DLNM) which fitted all data in one model. LD incidence showed a yearly peak in August and September. A total of 614 cases were included. Given seasonality, a sequence of precipitation, followed by high relative humidity and low wind speed showed a statistically significant association with the number of cases 6 to 4 days later. We discussed the advantages of DLNM in this context.

In Vitro Susceptibility of Burkholderia cepacia Complex Isolated from Cystic Fibrosis Patients to Ceftazidime-Avibactam and Ceftolozane-Tazobactam.

We tested the in vitro susceptibility of ceftazidime-avibactam and ceftolozane-tazobactam and 13 other antibiotics against 91 Burkholderia cepacia complex (BCC) strains isolated from cystic fibrosis patients since 2012. The highest susceptibility (82%) was found for trimethoprim-sulfamethoxazole. Eighty-one and 63% of all BCC strains were susceptible to ceftazidime-avibactam and ceftolozane-tazobactam, respectively. For temocillin, ceftazidime, piperacillin-tazobactam, and meropenem, at least 50% of the strains were susceptible. B. stabilis seems to be more resistant than other BCC species.

Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe.

BACKGROUND: Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001. METHODS: Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)-infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0. RESULTS: The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%-9.5%) in 2008-2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones. CONCLUSIONS: Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected.

Design and validation of a qPCR assay for accurate detection and initial serogrouping of Legionella pneumophila in clinical specimens by the ESCMID Study Group for Legionella Infections (ESGLI).

Prompt detection of Legionella pneumophila is essential for rapid investigation of legionellosis. Furthermore, as the majority of L. pneumophila infections are caused by serogroup 1 (sg1) strains, rapid identification of such strains can be critical in both routine and outbreak scenarios. The ESCMID Study Group for Legionella Infections (ESGLI) was established in 2012 and immediately identified as a priority the validation of a reliable, easy to perform and interpret, cost-effective qPCR assay to standardise the detection of L. pneumophila DNA amongst members. A novel L. pneumophila assay targeting the mip gene was designed and combined with previously published methodologies amplifying the sg1 marker (wzm) and the green fluorescent protein gene (gfp) internal process control. The resulting triplex assay was validated internationally on the three qPCR platforms used by the majority of European Legionella reference laboratories: ABI 7500 (Life Technologies), LightCycler 480 Instrument II (Roche) and Rotor-Gene Q (Qiagen). Clinical and EQA specimens were tested together with a large panel of strains (251 in total) to validate the assay. The assay proved to be 100% specific for L. pneumophila and sg1 DNA both in silico and in vitro. Efficiency values for mip and wzm assays ranged between 91.97 and 97.69%. Limit of detection values estimated with 95% confidence were adopted for mip and wzm assays on all three qPCR platforms. Inhibition was not observed. This study describes a robust assay that could be widely implemented to standardise the molecular detection of L. pneumophila among ESGLI laboratories and beyond.

Sequence-based typing of Legionella pneumophila serogroup 1 clinical isolates from Belgium between 2000 and 2010.

Sequence-based typing (SBT) is a discriminatory method widely used to genotype Legionella pneumophila strains. A total of 86 clinical L. pneumophila serogroup 1 (sg1) isolates, collected between January 2000 and December 2010 in the two Belgian National Reference Centres for Legionella pneumophila, were genotyped using the internationally standardised SBT protocol of the European Working Group for Legionella Infections (EWGLI). The isolates could be classified into 31 different sequence types (ST, index of diversity: 0.879). The obtained STs were submitted to the EWGLI SBT-database for L. pneumophila. In our study, ST47 (27.9%) and ST1 (19.8%) were the most frequently detected STs. The detected profiles were a combination of both frequently isolated and unique STs, and of both worldwide distributed and more local strains. Two STs, ST880 and ST881, were new to the EWGLI database. In conclusion, we characterised L. pneumophila sg1 isolates with the SBT method, and created a Belgian profile database that will be useful for future epidemiological studies.

Production of recombinant antigens of Ureaplasma parvum serotypes 3 and 6 for development of a serological assay.

Recombinant antigens of Ureaplasma parvum serotypes 3 and 6 were produced in order to develop a serological assay for Ureaplasma antibody detection. The genes of the multiple banded antigen (MBA) were amplified by PCR and cloned in a pTrcHis TOPO plasmid. Purified recombinant proteins were evaluated in Western blotting and enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies and human sera. Our approach was successful in the production of the recombinant MBAs (rMBAs) for serotypes 3 and 6. The antigens tested positive with serotype-specific monoclonal antibodies in Western blotting and in ELISA. Prominent reactions were detected with the rMBAs and their homologous monoclonal antibodies. Strong cross-reactions were visible in ELISA between rMBA 3 and the monoclonal antibodies from the other U. parvum serotypes. A weak cross-reaction was seen with rMBA 3 and the monoclonal antibody from serotype 4. rMBA 6 showed cross-reaction only with the monoclonal antibody from U. parvum serotype 1. Fifty-one percent of the sera obtained from culture-positive women reacted with one or both rMBAs. Only three (15%) of the sera from culture-negative women reacted with the rMBA. The positive reactions were observed only with rMBA 6. These preliminary tests showed the potential usefulness of the rMBAs produced for detecting an antibody response against Ureaplasma antigens.

Development of an enzyme-linked immunosorbent assay for serotyping ureaplasma urealyticum strains using monoclonal antibodies.

Ureaplasma urealyticum comprises 14 serotypes. The existing serotyping methods all use polyclonal antibodies. These methods are time-consuming and labor-intensive, and they cannot always be performed on primary isolates; in addition, the results are difficult to interpret. We developed a new enzyme-linked immunosorbent assay (ELISA) method using serotype-specific monoclonal antibodies (MAbs) to enable the serotyping of U. urealyticum isolates from primary broth cultures. Each of the 14 serotype reference strains was tested against 14 selected MAbs. Homologous reactions were very strong, while heterologous reactions were negligible. Three cross-reactions were observed: MAb 5 cross-reacted with serotype 2, MAb 14 cross-reacted with serotype 3, and MAb 8 cross-reacted with serotype 13. Despite the cross-reactions observed, all the serotype reference strains of U. urealyticum could be identified and differentiated using a combination of MAbs. Reproducibility was analyzed with a fractionated antigenic preparation and with several freshly prepared antigens of the same strain. No significant interrun variation was found with the fractionated antigen, but significant variations in optical density (OD) values were found when freshly prepared antigens were tested. However, the variation in OD values did not influence the overall interpretation of the ELISA: reactions with homologous MAbs were always prominent compared to those of the negative controls. This newly developed ELISA using MAbs seems promising for serotyping of U. urealyticum clinical isolates.

Development of monoclonal antibodies against Ureaplasma urealyticum serotypes and their use for serotyping clinical isolates.

Monoclonal antibodies (MAbs) against Ureaplasma urealyticum serotype 2, 5, 7, 8, 10, 11, 12, and 13 reference strains were developed. The reactivities of these MAbs with the 14 serotype reference strains was verified by colony immunofluorescence assay and Western blot assay. MAbs against serotypes 2, 7, 10, 11, and 12 were serotype specific, whereas MAbs against serotypes 5, 8, and 13 showed cross-reactivity. All MAbs against serotype 5 were cross-reactive with serotype 2, and one showed, in addition, cross-reactivity to serotypes 9 and 10. Mutual cross-reactivities were observed between MAbs against serotypes 8 and 13. The usefulness of the MAbs for the serotyping of U. urealyticum strains was evaluated by serotyping 21 selected clinical isolates. A complete set of MAbs (the newly developed MAbs and the previously described MAbs against serotypes 1, 3, 4, 6, 9, and 14) as well as a complete set of polyclonal antibodies (PAbs), PAbs 1 to 14, were used. MAbs were able to identify 18 of 21 isolates including 2 isolates with mixed serotypes. Polyreactivity, which occurred with 19 of the 21 isolates with PAbs, was not observed by the use of MAbs. MAbs seem to be a more valuable tool than PAbs for serotyping and could help in investigating a possible link between the expression or variability of the serotype-specific antigens and pathogenicity.