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Blood cultures detected as positive by the automated system but negative by microscopy and subculture are considered as "false-positives." Several causes have been identified, including hyperleukocytosis or the presence of fastidious bacteria, but as many cases remain unexplained we aimed to investigate the false positives occurring in our laboratory. We retrospectively collected data on blood cultures received over a period of 12 months to determine factors associated with the false-positive vials. We then prospectively validated our findings on the false-positive results occurring over a 3.5-month period. We finally applied scanning electron microscopy (SEM) on 63 false positives and molecular approaches on a subset of them. In the retrospective study, 154 (85%) of the 181 false-positive identified were positive following less than 4 h of incubation and were considered as "early false-positives." By performing ROC curves on these early false positives, we demonstrate that the absolute number of leukocytes is in fact the most discriminating factor of early false positivity (p < 0.001). This phenomenon can be the consequence of either a high blood culture volume (p < 0.001) or hyperleukocytosis (p < 0.001). In the prospective study, the use of a threshold of 219 million of leukocytes per vial enabled the identification of 97% of the early false positives. Finally, SEM and specific qPCR enabled three additional identifications while 16S rRNA/nanopore sequencing enabled the detection of Helicobacter cinaedi bacteremia and a polymicrobial infection. A high absolute number of leukocytes in blood cultures explains most false positives, thereby making it possible to target additional microbiological investigations. [ABSTRACT FROM AUTHOR]

We studied retrospectively 651 PCR-confirmed Bartonella infections diagnosed at the French reference center for bartonellosis from 2014 to 2019. The most common form was cat-scratch disease (89%) followed by endocarditis (9%). Disseminated forms (2%) mainly presented as bacillary angiomatosis or peliosis hepatis in solid organ transplant recipients. [ABSTRACT FROM AUTHOR]

We aimed to compare respiratory pathogen carriage by PCR during three different time periods in 2020 in sheltered homeless people in Marseille, France. The overall prevalence of respiratory pathogen carriage in late March–early April (69.9%) was significantly higher than in late April (42.3%) and mid-July (45.1%). Bacterial carriage significantly decreased between late March–early April and late April. SARS-CoV-2 was detected only in late March–early April samples (20.6%). Measures aiming at mitigating SARS-CoV-2 transmission were effective and also impacted bacterial carriage. Seasonal variations of bacterial carriage between winter and summer in this population were not marked. [ABSTRACT FROM AUTHOR]

ELISA and chemiluminescence serological assays for COVID-19 are currently incorporating only one or two SARS-CoV-2 antigens. We developed an automated Western immunoblotting as a complementary serologic assay for COVID-19. The JessTM Simple Western system, an automated capillary-based assay, was used, incorporating an inactivated SARS-CoV-2 lineage 20a strain as the source of antigen, and total immunoglobulins (IgG, IgM, IgA) detection. In total, 602 sera were tested including 223 from RT-PCR-confirmed COVID-19 patients, 76 from patients diagnosed with seasonal HCoVs and 303 from coronavirus-negative control sera. We also compared this assay with the EUROIMMUN® SARS-CoV-2 IgG ELISA kit. Among 223 sera obtained from RT-PCR-confirmed COVID-19 patients, 180/223 (81%) exhibited reactivity against the nucleocapsid and 70/223 (31%) against the spike protein. Nucleocapsid reactivity was further detected in 9/76 (14%) samples collected from patients diagnosed with seasonal HCoVs and in 15/303 (5%) coronavirus-negative control samples. In the subset of sera collected more than 2 weeks after the onset of symptoms, the sensitivity was 94% and the specificity 93%, the latter value probably reflecting cross-reactivity of SARS-CoV-2 with other coronaviruses. The automated Western immunoblotting presented a substantial agreement (90%) with the compared ELISA (Cohen's Kappa=0.64). Automated Western immunoblotting may be used as a second line test to monitor exposure of people to HCoVs including SARS-CoV-2. [ABSTRACT FROM AUTHOR]

The objective of this study is to determine the acquisition of multidrug-resistant (MDR) bacteria and antibiotic resistance-encoding genes by French Hajj pilgrims and associated risk factors. Pilgrims traveling during the 2017 and 2018 Hajj were recruited. All pilgrims underwent two successive systematic nasopharyngeal and rectal swabs, pre- and post-Hajj. Specific culture media were used to screen for MDR bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant bacteria, and extended spectrum beta-lactamase producing Enterobacteriaceae (ESBL-E). qPCR was used to identify antibiotic resistance-encoding genes from cultured isolates. Direct screening of genes encoding for colistin resistance (mcr-1, 2, 3, 4, 5, and 8) from nasopharyngeal and rectal swabs was performed using qPCR, and positive qPCR results were simultaneously tested by sequencing. There were 268 pilgrims included. The percentage of pilgrims acquiring MDR bacteria during the Hajj was 19.4%. A total of 81 strains were isolated (1 carbapenem-resistant Acinetobacter baumannii, 12 MRSA, and 68 ESBL-E). ESBL-E strains were found in rectal samples of 6.0% pilgrims pre-Hajj and of 16.4% pilgrims post-Hajj. Only 0.4% pilgrims were positive for CARB post-Hajj and 1.9% carried nasal MRSA pre- and post-Hajj. In addition, 23 (8.6%) post-Hajj rectal swabs were positive for mcr genes (19 mcr-1 gene and 4 mcr-4 gene). No significant association was found between co-factors and acquisition of MDR bacteria or mcr genes. MDR bacteria and genes are acquired by pilgrims during the Hajj mass gathering. Rationalization of antibiotic consumption and implementation of measures to prevent transmission of bacteria among pilgrims during the event are of paramount importance. [ABSTRACT FROM AUTHOR]

The acquisition of enteric pathogens and risk factors for Hajj-associated diarrhea in Hajj pilgrims is poorly documented. Pilgrims from Marseille participating in the Hajj in 2016–2018 underwent successive systematic rectal swabbing before and after their travel. Carriage of the main enteric pathogens was assessed by real-time PCR. Baseline demographics, adherence to individual preventive measures, gastrointestinal symptoms, and treatments were recorded. A total of 376 pilgrims were included. The median age was 62.0 years. During the Hajj, 18.6% presented at least one gastrointestinal symptom, 13.8% had diarrhea, and 36.4% had acquired at least one enteric pathogen. Enteropathogenic Escherichia coli (EPEC) and Enteroaggregative E. coli (EAEC) were the pathogens most frequently acquired by pilgrims (17.6% and 14.4%, respectively). Being female was associated with increased frequency of gastrointestinal symptoms during the pilgrimage (aOR = 2.38, p = 0.004). Enterohemorrhagic Escherichia coli (EHEC) acquisition was associated with a four-fold higher risk of reporting at least one gastrointestinal symptom and diarrhea (aOR = 3.68 and p = 0.01 and aOR = 3.96 and p = 0.01, respectively). Pilgrims who suffered from diarrhea were more likely to wash their hands more often (aOR = 2.07, p = 0.03) and to be either overweight (aOR = 2.71, p = 0.03) or obese (aOR = 2.51, p = 0.05). Enteric bacteria such as E. coli that are frequently associated with traveler's diarrhea due to the consumption of contaminated food and drink were frequently found in pilgrims. Respecting strict measures regarding food and water quality during the Hajj and adherence to preventive measures such as good personal hygiene and environmental management will help reduce the burden of gastrointestinal infections at the event. [ABSTRACT FROM AUTHOR]

Previous reports have suggested that children are less affected than adults by SARS-CoV-2. We analyzed SARS-CoV-2 diagnoses between February 27, 2020, and March 14, 2020, and mortality among positive patients in Marseille university hospitals. Of 4050 tested individuals, 228 were positive. Deaths occurred in 2/99 documented cases (both > 85 year-old). Children were majorly asymptomatic. Incidence increased by 7.4-fold between 1–5 and 45–65 years then decreased. It was significantly lower among 0–1 year- (0%) and 1–5 (1.1%) and 5–10 (3.6%)-year-old children than among subjects > 18 years (6.5%). Viral loads did not differ between children and adults. Children may not contribute significantly to virus circulation. [ABSTRACT FROM AUTHOR]

Homeless people are often exposed to unhygienic environments as well as to animals carrying arthropods which both transmit zoonotic infections and human louse-borne pathogens. We attempted to determine the prevalence of antibodies against several vector-borne and zoonotic pathogens among homeless adults living in Marseille. During the 2005–2015 period, we collected sera samples from 821 homeless adults living in shelters. Antibodies against Bartonella quintana, Bartonella henselae, Borrelia recurrentis, Coxiella burnetii, Francisella tularensis (with a cut-off of 1:100), Rickettsia akari, Rickettsia conorii, Rickettsia felis, Rickettsia prowazekii, and Rickettsia typhi (with a cut-off of 1:64) were searched by microimmunofluorescence (MIF). MIF-positive serum samples were confirmed by cross-adsorption to characterise cross-reacting antigens and immunoblotting. Positive sera by Western blot were further tested using qPCR. We evidenced a prevalence of 4.9% seroreactivity to at least one pathogen including phase II C. burnetii (2.1%), B. quintana (1.7%), R. conorii (0.4%), R. prowazekii (0.4%), R. typhi (0.1%), B. recurrentis (0.1%), and F. tularensis (0.1%). No DNA from any pathogens was detected. A comparison with studies conducted prior to the 2000–2003 period showed a decrease in the overall seroprevalence of several vector-borne and zoonotic infections. [ABSTRACT FROM AUTHOR]

Infectious meningitis is a medical urgency and rapid detection of the causative pathogen into the cerebrospinal fluid (CSF) is mandatory to guide the management of patients. We compared the performances of the multiplexed PCR FilmArray® ME panel with standard microbiological analyses, for rapid diagnosis of infectious meningitis. All the CSF samples received in our routine laboratory for the diagnosis of infectious meningitis were prospectively analyzed by the FilmArray® ME panel for the detection of fourteen targets in parallel to standard routine real-time PCR assays and bacterial culture. We reviewed clinical and biological records of patients for whom a discrepant result was obtained to achieve a definite diagnosis. Among 1124 CSF samples tested over a 43-week period, 113 (10.1%) and 87 (7.74%) were positive using the FilmArray® ME panel and the standard techniques, respectively. Among 40 CSF samples which yielded discrepant results, 34 were positive only using the FilmArray® ME panel and 6 were positive only using standard techniques. A total of 16/34 (47.1%) FilmArray® ME panel−positive CSF, and 6/6 (100%) of standard technique−positive CSF were interpreted as true positive. We were able to estimate the sensitivity, the specificity, the positive predictive value, and the negative predictive value of the FilmArray® ME panel at 94.2%, 98.2%, 84.3%, and 99.4%, respectively. The FilmArray® ME panel is an efficient tool for the rapid diagnosis of infectious meningitis at the point-of-care. Its higher sensitivity compared with that of standard molecular biology and culture techniques yields an increase of true positive diagnosis. [ABSTRACT FROM AUTHOR]

Coxiella burnetii cardiovascular prosthetic infections are associated with high morbidity and mortality and represent a major health problem due to the lack of standardized management. We were confronted with a C. burnetii infection on Bentall-De Bono prosthesis characterized by a history of vascular infection with relapse that prompted us to screen for cases of C. burnetii on Bentall-De Bono vascular prosthesis monitored in our center. We screened patients between 1991 and 2019, from the French national reference center for Q fever. A microbiological criterion in addition to a lesional criterion was necessary to diagnose C. burnetii persistent vascular infection. Two thousand five hundred and eighty two patient were diagnosed with Coxiella burnetii infection and 160 patients with persistent C. burnetii vascular infection prosthesis, 95 of whom had a vascular prosthesis, including 12 with Bentall-De Bono prosthesis. Among patients with persistent C. burnetii prosthetic vascular infection, patients with Bentall-De Bono prostheses were significantly more prone to develop complications such as aneurysm, fistula, and abscess (62 versus 32%, two-sided Chi-square test, p = 0.04). All but one patient were treated with doxycycline and hydroxychloroquine for a mean (± standard deviation) period of 29.4 ± 13.6 months. Among the 12 patients, 5 had cardio-vascular complications, and 5 had prolonged antibiotherapy with doxycycline and hydroxychloroquine. Patients with C. burnetii vascular infection on Bentall-De Bono tend to be at high risk of developing complications (fistula, aneurysm, abscess, death). Surgery is rarely performed. Clinical, serological, and PET scanner imaging follow-up is recommended. [ABSTRACT FROM AUTHOR]

Vaginosis is a dysbiotic condition of the vaginal cavity that has deleterious effects during pregnancy. The role of methanogens in this disease is unknown since current methods of investigation are not appropriate for the search of methanogens. We prospectively investigated the presence of methanogens in vaginal specimens collected from 33 women thereafter diagnosed with bacterial vaginosis and 92 women thereafter diagnosed without bacterial vaginosis (control group) by direct microscopic examination and fluorescent in situ hybridization, PCR-sequencing, and real-time PCR and isolation and culture. These investigations found only one methanogen, Methanobrevibacter smithii, exclusively in 97% bacterial vaginosis specimens and in two intermediate microbiota specimens. M. smithii was detected microscopically in 2/20 specimens analyzed, by PCR-based observations in 34/125 specimens with 99% sequence similarity with the reference 16S rRNA and mcrA gene sequences and was cultured in 9/40 specimens. These data suggest that the detection of M. smithii could be used as a biomarker for the laboratory diagnosis of bacterial vaginosis. [ABSTRACT FROM AUTHOR]

Since effective empirical antibiotic therapy is a key factor for survival, local antibiotic resistance epidemiology is critical. We aimed to identify current trends in antibiotic resistance for key antibiotics obtained over 16 years (2001-2016) for invasive infections corresponding to empirical treatment in a large hospital centre in Marseille, France.From January 2014 to December 2016, we have collected all data on antibiotic susceptibility from public laboratory hospitals, and a retrospective analysis was performed on key antibiotics in blood cultures since 2001. A total of 99,932 antibiotic susceptibility testings (ASTs) were analysed, and proportion of pan-drug resistant (PDR = resistant to all antibiotics tested) and extensively drug-resistant (XDR = resistant to all except for two classes) strains were < 0.03 and 0.5%, respectively. Between 2001 and 2016, we found an increase of resistance to third-generation cephalosporins for E. coli invasive strains (0% vs 17.8%; p < 10−5) and K. pneumoniae (8% vs 35.4%; p = 0.001) along with a decrease of methicillin-resistant S. aureus strains (31% vs 19.8%; p = 0.006). Moreover, during the 3-year period, a significant increase of wild-type strains, susceptible to all antibiotics tested, was observed in invasive infections. Regarding bacteraemia involving Enterobacteriaceae and S. aureus, empirical therapy is effective in > 99% cases. Active epidemiological surveillance is necessary because antibiotic resistance remains unpredictable. [ABSTRACT FROM AUTHOR]

The nasopharynx is the primary site of colonization by respiratory pathogen that constitutes the port of entrance in the respiratory tract. The role of mucosal respiratory microbiota in infection has been recently emphasized; therefore, we aimed to assess if a specific respiratory microbiota profile was associated with symptomatic infection and/or with presence of respiratory viruses. We performed a case-control study to characterize the healthy respiratory microbiota and its alteration during acute viral infections. Next-generation sequencing of the 16S rRNA gene was applied to 225 nasopharyngeal samples from 177 patients with viral respiratory infection and 48 matched healthy controls. We evidenced an important decrease of bacterial alpha-diversity in patients with symptomatic respiratory infection and a loss of the healthy core microbiota, specifically anaerobes and Prevotella spp. Moreover, eight respiratory pathogens were enriched in these patients, including Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, Dol osigranulum pigrum and Corynebacterium propinquum/pseudodiphtheriticum, whose role in respiratory infection is unclear. The asymptomatic carrier of influenza harbors a microbiota similar to healthy subjects, suggesting a critical role of microbiota in the clinical expression of viruses. These data suggest that the commensal microbiota plays a significant role in susceptibility to viral infection. The frequent co-detection of virus and bacteria raises the question of a strategy to prevent bacterial disease, focusing on the prevention of nasopharyngeal colonization through effective antibiotic treatment. In addition to antibiotics, further studies should test preventive or therapeutic interventions for maintaining or restoring a healthy nasopharyngeal microbiota. [ABSTRACT FROM AUTHOR]

In 2009, the European Centre for Disease Prevention and Control (ECDC) estimated that multidrug-resistant (MDR) bacterial infections were responsible for 25,000 extra-deaths per year. In 2015, another report estimated that 12,500 extra-deaths were attributable to MDR bacteria every year in France. Recently, the United Nations claimed that resistance to antimicrobials was a global scourge, forecasting 10 million deaths in 2050. Surprisingly, our antibiotic resistance surveillance system in Marseille, France, did not allowed us to observe similar trends. We herein compared our data on extremely drug-resistant (XDR)/pandrug-resistant (PDR) patient extra-deaths to evaluations and predictions from these reports. First, we retrospectively collect and analyze antibiotic resistance data produced by our settings between November 2009 and March 2015 to look for 30-day deaths attributable to XDR/PDR strains belonging to 11 bacterial species/genus. In parallel, we performed a PubMed literature search to look for articles published prior to July 2016 and describing human deaths due to PDR strains. Overall, 35,723 patients were infected by at least one bacterial species/genus of interest and 85 by XDR/PDR strains. Of these patients, only one death was attributable to a XDR bacterial infection in a patient with strong comorbidities and two consecutive septic shocks. Our literature review shows that only four articles described human deaths due to PDR bacteria. All together, these data allowed us to conclude that there is a large discrepancy between the real count of deaths attributable to XDR/PDR bacteria and alarmist predictions. [ABSTRACT FROM AUTHOR]

Current technological level made possible the quick identification and culture of the SARS-CoV-2, an emerging coronavirus that caused until March 3, 2020, 90,870 confirmed cases of infections, with outside China a still limited spread (10,556 cases) and low mortality (166 deaths) (https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200303-sitrep-43-covid-19.pdf?sfvrsn=2c21c09c%5f2). This nasopharyngeal swab sample arrived at 8:30 pm in our clinical microbiology and virology laboratory at IHU Méditerranée Infection, which has been performing the routine diagnosis of SARS-CoV-2, 24 h a day, 7 days a week since the end of January 2020 for all suspected cases of Covid-19 (the SARS-CoV-2-associated disease). We carried out SARS-CoV-2 RNA detection by two first-line real-time reverse transcription (RT)-PCR assays [[9]], one of which (SpikeP ps80) was developed in-house as soon as the first SARS-CoV-2 genome (GenBank Accession no. [Extracted from the article]

In a preliminary clinical study, we observed that the combination of hydroxychloroquine and azithromycin was effective against SARS-CoV-2 by shortening the duration of viral load in Covid-19 patients. It is of paramount importance to define when a treated patient can be considered as no longer contagious. Correlation between successful isolation of virus in cell culture and Ct value of quantitative RT-PCR targeting E gene suggests that patients with Ct above 33–34 using our RT-PCR system are not contagious and thus can be discharged from hospital care or strict confinement for non-hospitalized patients. [ABSTRACT FROM AUTHOR]

Molecular methods have been considered to be the gold standard for the diagnosis of infectious lymphadenitis. However, culture remains critical in the case of low bacterial concentrations. We used molecular assays and culture to examine fresh lymph node biopsies from patients with suspected infectious lymphadenopathy. We analyzed 1762 lymph node biopsies of which 522 (30%) samples were found positive by real-time PCR; the most commonly amplified bacteria were Bartonella henselae (n = 438, 84%), Francisella tularensis (n = 46, 9%), and Mycobacterium spp. (n = 29, 6%). PCR amplification and sequencing of the 16S rDNA were positive for 359 (20%) lymph node specimens including mainly B. henselae (n = 167, 47%), Staphylococcus spp. (n = 77, 21%), and Streptococcus spp. (n = 41, 11%). In total, 351 lymph nodes were cultured on agar plates and 77 (22%) were positive. Significantly more lymph nodes infected by Gram-positive easy-growing agents were diagnosed by culture (n = 45) than by 16S rDNA PCR (p = 0.02). Culture remains critical for the diagnosis of easy-growing bacteria and mycobacteria; clinicians should be aware that a negative molecular result does not imply absence of infection. [ABSTRACT FROM AUTHOR]

Despite advances in medical, surgical, and critical care, infective endocarditis (IE) remains associated with considerable morbidity and mortality. We evaluated the performance of the Marseille score, including clinical data and biological tests obtained within 2 h, to identify patients at high risk of IE in order to initiate early antimicrobial treatment. This was secondarily confirmed using modified ESC criteria combined with molecular testing and (18)fluorodeoxyglucose-positron emission tomography/computed tomography as diagnostic tools. In a prospective cohort study, we enrolled 484 patients with cardiovascular predisposition and clinical suspicion of IE from 2011 to 2013. The final diagnosis was definite IE in 123 patients and possible IE in 107. Marseille score was calculated adding one point for each present parameter (range 0-9). This score includes clinical, epidemiological (male, fever, splenomegaly, clubbing, vascular disease and stroke) and biological criteria (Leucocytes >10,000/mm3, sedimentation rate (SR) > 50/mm or C reactive protein >10 mg/L and hemoglobin <100 g/l). A score of 2 or more performed best in predicting IE in patients with predisposing heart lesions. Sensitivity was better on left-side heart lesions (94%) than on right-side heart lesions (85%) (p = 0.04) and better for valvulopathy (94%) than intra cardiac devices (84%) (p = 0.02). The predictive positive value of prosthetic valves was greater than that of native valves (p = 0.02). Using our simple Marseille score combined with our standardized diagnostic procedures would help improve IE management by focusing on early empiric treatment within 2 h of admission for patients with cardiac predisposition factors. [ABSTRACT FROM AUTHOR]

As such, we proposed vaginal self-sampling in women who experienced miscarriage or other pregnancy problems, and we tested the samples for pathogens known to be responsible for miscarriages or other pregnancy problems in rural West Africa. We obtained no vaginal samples positive for I L. monocytogenes i among the healthy women, and among the samples from women who experienced miscarriage, 2/43 (4.6%) were positive for I L. monocytogenes i . [Extracted from the article]

An erratum to this paper has been published: https://doi.org/10.1007/s10096-020-04047-8. [ABSTRACT FROM AUTHOR]