Contribution of PCR to Differential Diagnosis between Patients with Whipple Disease and Tropheryma whipplei Carriers.

Differentiation between Whipple disease (WD) patients and patients carrying Tropheryma whipplei but suffering from disease other than WD ("carriers") remains complex. We aimed to evaluate T. whipplei PCR among patients with WD and carriers in a large cohort at our referral clinical microbiology laboratory. This is an observational retrospective cohort study, including all patients between 2008 and 2020 with at least one positive result for T. whipplei using the real-time PCR RealCycler TRWH-UX kit. A total of 233 patients were included: 197 were considered carriers, and 36 had WD. Among the WD patients, 32 underwent biopsies, of which 18 (56%) had a positive periodic acid-Schiff (PAS) staining. Among the 27 duodenal biopsy specimens, 13 (48%) were PAS positive. PCR results before antibiotic treatment were positive in both feces and saliva in 16/21 WD (76%) patients and 68/197 (35%) carriers (P < 0.001). Duodenal biopsy specimens yielded positive PCR in 20/22 (91%) WD patients and 27/72 (38%) carriers (P < 0.001). The cycle threshold (CT) value detected in duodenal biopsy specimens from WD patients was significantly lower than that of carriers (P < 0.001), regardless of the PAS staining results. For a diagnosis of WD, duodenal PCR sensitivity and specificity at a CT value below 30 were 52.4% and >99.9%, respectively. The high specificity of duodenal PCR with low CT values may help confirming the diagnosis of WD, especially in patients with negative PAS results in digestive biopsy specimens, who represent half of all patients. A low PCR CT value from a duodenal biopsy specimen provides valuable guidance, especially in patients with PAS-negative results.

Molecular Diagnosis of Invasive Aspergillosis and Detection of Azole Resistance by a Newly Commercialized PCR Kit.

Aspergillus fumigatus is the main species responsible for aspergillosis in humans. The diagnosis of aspergillosis remains difficult, and the rapid emergence of azole resistance in A. fumigatus is worrisome. The aim of this study was to validate the new MycoGENIE A. fumigatus real-time PCR kit and to evaluate its performance on clinical samples for the detection of A. fumigatus and its azole resistance. This multiplex assay detects DNA from the A. fumigatus species complex by targeting the multicopy 28S rRNA gene and specific TR34 and L98H mutations in the single-copy-number cyp51A gene of A. fumigatus The specificity of cyp51A mutation detection was assessed by testing DNA samples from 25 wild-type or mutated clinical A. fumigatus isolates. Clinical validation was performed on 88 respiratory samples obtained from 62 patients and on 69 serum samples obtained from 16 patients with proven or probable aspergillosis and 13 patients without aspergillosis. The limit of detection was <1 copy for the Aspergillus 28S rRNA gene and 6 copies for the cyp51A gene harboring the TR34 and L98H alterations. No cross-reactivity was detected with various fungi and bacteria. All isolates harboring the TR34 and L98H mutations were accurately detected by quantitative PCR (qPCR) analysis. With respiratory samples, qPCR results showed a sensitivity and specificity of 92.9% and 90.1%, respectively, while with serum samples, the sensitivity and specificity were 100% and 84.6%, respectively. Our study demonstrated that this new real-time PCR kit enables sensitive and rapid detection of A. fumigatus DNA and azole resistance due to TR34 and L98H mutations in clinical samples.

Acquired Flucytosine Resistance during Combination Therapy with Caspofungin and Flucytosine for Candida glabrata Cystitis.

Treatment of Candida glabrata cystitis remains a therapeutic challenge, and an antifungal combination using flucytosine is one option. We describe two patients with refractory C. glabrata cystitis who failed flucytosine combined with caspofungin with early-acquired high-level resistance to flucytosine due to nonsense mutations in the FUR1 gene. Rapidly acquired flucytosine resistance with microbiological failure should discourage combination of caspofungin and flucytosine during urinary candidiasis.

Bacterial pathogens associated with hidradenitis suppurativa, France.

Hidradenitis suppurativa (HS) is a skin disease characterized by recurrent nodules or abscesses and chronic suppurating lesions. In the absence of clear pathophysiology, HS is considered to be an inflammatory disease and has no satisfactory medical treatment. Recently, prolonged antimicrobial treatments were shown to improve or resolve HS lesions. We prospectively studied the microbiology of 102 HS lesions sampled from 82 patients using prolonged bacterial cultures and bacterial metagenomics on 6 samples. Staphylococcus lugdunensis was cultured as a unique or predominant isolate from 58% of HS nodules and abscesses, and a polymicrobial anaerobic microflora comprising strict anaerobes, milleri group streptococci, and actinomycetes was found in 24% of abscesses or nodules and in 87% of chronic suppurating lesions. These data show that bacteria known to cause soft tissue and skin infections are associated with HS lesions. Whether these pathogens are the cause of the lesions or are secondary infectious agents, these findings support targeted antimicrobial treatment of HS.

Successful identification of clinical dermatophyte and Neoscytalidium species by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Dermatophytes are keratinolytic fungi responsible for a wide variety of diseases of glabrous skin, nails, and hair. Their identification, currently based on morphological criteria, is hindered by intraspecies morphological variability and the atypical morphology of some clinical isolates. The aim of this study was to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as a routine tool for identifying dermatophyte and Neoscytalidium species, both of which cause dermatomycoses. We first developed a spectral database of 12 different species of common and unusual dermatophytes and two molds responsible for dermatomycoses (Neoscytalidium dimidiatum and N. dimidiatum var. hyalinum). We then prospectively tested the performance of the database on 381 clinical dermatophyte and Neoscytalidium isolates. Correct identification of the species was obtained for 331/360 dermatophytes (91.9%) and 18/21 Neoscytalidium isolates (85.7%). The results of MALDI-TOF MS and standard identification disagreed for only 2 isolates. These results suggest that MALDI-TOF MS could be a useful tool for routine and fast identification of dermatophytes and Neoscytalidium spp. in clinical mycology laboratories.

Horizontal transmission of Streptococcus pneumoniae in the surgical ward: a rare source of nosocomial wound infection.

Streptococcus pneumoniae is rarely isolated from nosocomial infections. We report an outbreak of 4 nosocomial-acquired surgical site infections due to S pneumoniae after retropubic simple prostatectomy. The likely source was detected in the rhinopharynx of the surgeon. After the implementation of recommendations, no new cases have been recorded.

Rapid identification of Staphylococci isolated in clinical microbiology laboratories by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) of intact bacteria yields a reproducible spectrum depending upon growth conditions, strain, or species. Using whole viable bacteria we describe here the application of MALDI-TOF-MS to the identification of coagulase-negative staphylococci (CoNS). Our aim was, once a bacterium has been recognized as Micrococcaceae, to identify peaks in the spectrum that can be used to identify the species or subspecies. MALDI-TOF-MS was performed using bacteria obtained from one isolated colony. One reference strain for each of the 23 clinically relevant species or subspecies of Micrococcaceae was selected. For each reference strain, the MALDI-TOF-MS profile of 10 colonies obtained from 10 different passages was analyzed. For each strain, only peaks that were conserved in the spectra of all 10 isolated colonies and with a relative intensity above 0.1 were retained, thus leading to a set of 3 to 14 selected peaks per strain. The MALDI-TOF-MS profile of 196 tested strains was then compared with that of the set of selected peaks of each of the 23 reference strains. In all cases the best hit was with the set of peaks of the reference strain belonging to the same species as that of the tested strain, thus demonstrating that the 23 sets of selected peaks can be used as a database for the rapid species identification of CoNS. Similar results were obtained using four different growth conditions. Extending this strategy to other groups of relevant pathogenic bacteria will allow rapid bacterial identification.

Microbiological diagnosis of empyema in children: comparative evaluations by culture, polymerase chain reaction, and pneumococcal antigen detection in pleural fluids.

BACKGROUND: Pleural empyema is an increasingly reported complication of pneumonia in children. Microbiological diagnostic tests for empyema by culture frequently have false-negative results due to previous administration of antibiotics. Molecular diagnosis by broad-range 16S ribosomal DNA (rDNA) polymerase chain reaction (PCR) and rapid pneumococcal antigen detection are reliable tools, but their diagnostic value has not been clearly established for pleural fluid samples. Pneumococcal antigen detection has only been validated for urine and cerebrospinal fluid samples. METHODS: Over 4 years, pleural fluid specimens were collected from 78 children with pleural empyema. Standard culture, pneumococcal antigen detection by latex agglutination (Pastorex; Bio-Rad) and immunochromatographic testing (Binax NOW Streptococcus pneumoniae), and 16S rDNA PCR were performed on these specimens. Pneumococcal identification by 16S rDNA PCR and sequencing was confirmed by pneumolysin PCR. RESULTS: Of the 78 cases of pleural empyema, 60 (77%) were microbiologically documented by culture or 16S rDNA PCR. Of the 40 pneumococcal empyema cases, 17 (43%) were only diagnosed by PCR and 23 with PCR and culture. The sensitivity and specificity of the latex antigen detection (with the use of culture and/or PCR as the test standard) were 90% and 95%, respectively. The immunochromatographic test detected pneumococcal antigens in 3 additional specimens for which latex agglutination results were negative, thereby increasing the sensitivity of antigen detection. CONCLUSIONS: Pneumococcal antigen detection in pleural fluid specimens from children provides a rapid and sensitive method of diagnosis of pneumococcal empyema, which can be confirmed by specific pneumolysin PCR when culture results are negative. Broad-range 16S rDNA PCR has value in detecting bacterial agents responsible for culture-negative pleural empyema.

Age-related prevalence and distribution of nontuberculous mycobacterial species among patients with cystic fibrosis.

We studied the prevalence and species distribution of nontuberculous mycobacteria (NTM) in relation to age in 385 patients with cystic fibrosis (CF) (mean age +/- standard deviation [range], 12.0 +/- 6.1 [1 to 24] years; sex ratio, 0.53) attending three Parisian centers. The overall prevalence of NTM in sputum was 8.1% (31 out of 385). The following NTM were isolated (n = 33): Mycobacterium abscessus (n = 13, 39.4%), Mycobacterium avium complex (MAC) (n = 7, 21.2%), Mycobacterium gordonae (n = 6, 18.2%), and other (n = 7, 21.2%). Sixteen patients met the American Thoracic Society microbiological criteria for NTM infection, including 11 patients positive for M. abscessus, 4 for MAC, and 1 for MAC and Mycobacterium kansasii. The overall prevalence of NTM was significantly lower in patients under 15 years old than for patients equal to or more than 15 years old (4.8 versus 14.9%, respectively; P = 0.001). M. abscessus was isolated at all ages, while MAC was not recovered before 15 years (prevalence of 0.0 and 5.2% in patients aged 1 to 14 and 15 to 24, respectively; P = 0.001).

Accuracy of phenotypic and genotypic testing for identification of Streptococcus pneumoniae and description of Streptococcus pseudopneumoniae sp. nov.

We have identified an unusual group of viridans group streptococci that resemble Streptococcus pneumoniae. DNA-DNA homology studies suggested that a subset of these isolates represent a novel species that may be included in the S. oralis-S. mitis group of viridans group streptococci. We suggest that this novel species be termed Streptococcus pseudopneumoniae. A combination of phenotypic and genetic reactions allows its identification. S. pseudopneumoniae strains do not have pneumococcal capsules, are resistant to optochin (inhibition zones, less than 14 mm) when they are incubated under an atmosphere of increased CO2 but are susceptible to optochin (inhibition zones, >14 mm) when they are incubated in ambient atmospheres, are not soluble in bile, and are positive by the GenProbe AccuProbe Pneumococcus test. The bile solubility test is more specific than the optochin test for identification of S. pneumoniae. Genetic tests for pneumolysin (ply) and manganese-dependent superoxide dismutase (sodA) and identification tests with a commercial probe, AccuProbe Pneumococcus, do not discriminate between the new species and S. pneumoniae.

Recurrent pneumococcal meningitis in a splenectomised HIV-infected patient.

BACKGROUND: Streptococcus pneumoniae is a major cause of human disease, especially in pre-school children and elderly people, as well as in special risk groups such as asplenic, antibody deficient patients, or presenting disruption of natural barriers. The occurrence of pneumococcal disease has increased with the onset of the HIV epidemic and the emergence of drug-resistance. CASE PRESENTATION: We report the case of an HIV-1-infected patient who experienced three episodes of recurrent pneumococcal meningitis over a 4-year period, despite chemoprophylaxis and capsular vaccination. CONCLUSIONS: Efficacy of anti-pneumococcal chemoprophylaxis and vaccination in HIV-infected patients are discussed in the light of this particular case.

Genetic basis of antibiotic resistance in Streptococcus agalactiae strains isolated in a French hospital.

The genetic basis of antibiotic resistance in 113 unrelated group B streptococci was studied by PCR. Ninety-four strains were resistant to tetracycline-minocycline, and tet(M) was detected in 85% of these isolates. Seventeen erythromycin-resistant strains contained the erm(B), erm(TR), or mef(A) gene. Eleven strains exhibited high-level resistance to kanamycin due to the presence of the aphA3 gene; eight of these strains were also highly resistant to streptomycin; aad-6-related sequences were detected in seven strains.

Use of 16S rRNA gene sequencing for identification of nonfermenting gram-negative bacilli recovered from patients attending a single cystic fibrosis center.

During 1999, we used partial 16S rRNA gene sequencing for the prospective identification of atypical nonfermenting gram-negative bacilli isolated from patients attending our cystic fibrosis center. Of 1,093 isolates of nonfermenting gram-negative bacilli recovered from 148 patients, 46 (4.2%) gave problematic results with conventional phenotypic tests. These 46 isolates were genotypically identified as Pseudomonas aeruginosa (19 isolates, 12 patients), Achromobacter xylosoxidans (10 isolates, 8 patients), Stenotrophomonas maltophilia (9 isolates, 9 patients), Burkholderia cepacia genomovar I/III (3 isolates, 3 patients), Burkholderia vietnamiensis (1 isolate), Burkholderia gladioli (1 isolate), and Ralstonia mannitolilytica (3 isolates, 2 patients), a recently recognized species.

Taxonomic dissection of the Streptococcus bovis group by analysis of manganese-dependent superoxide dismutase gene (sodA) sequences: reclassification of 'Streptococcus infantarius subsp. coli' as Streptococcus lutetiensis sp. nov. and of Streptococcus bovis biotype 11.2 as Streptococcus pasteurianus sp. nov.

The taxonomic dissection of the Streptococcus bovis-Streptococcus equinus group was carried out upon obtaining sequences for the manganese-dependent superoxide dismutase gene (sodA) of the type strains of S. bovis, Streptococcus caprinus, S. equinus, Streptococcus gallolyticus, Streptococcus infantarius, Streptococcus macedonicus and Streptococcus waius. The sodA sequences of 29 streptococcal strains of animal and human origin that were related to S. bovis were also sequenced. A phylogenetic analysis of the sodA sequences revealed that the S. bovis-S. equinus group comprises five different clusters that correspond to five distinct species. The type strains of S. bovis and S. equinus were associated in the same cluster, corresponding to the species S. equinus. The type strains of S. caprinus, S. gallolyticus, S. macedonicus and S. waius were associated in the same cluster, which defined a single species containing S. gallolyticus and its junior synonym S. caprinus, and S. macedonicus and its junior synonym S. waius. The two subspecies thought to constitute the species S. infantarius, namely S. infantarius subsp. infantarius and 'S. infantarius subsp. coli', were located in two distinct clusters. One of these clusters defined the species S. infantarius and included the type strain of S. infantarius subsp. infantarius. The other cluster defined 'S. infantarius subsp. coli', leading to the proposal of its reclassification as the novel species Streptococcus lutetiensis (NEM 782T = CIP 106849T). The remaining cluster comprised all of the strains previously identified as belonging to S. bovis biotype 11.2, leading to the proposal to reassign these strains to the novel species Streptococcus pasteurianus (NEM 1202T = CIP 107122T). The results of the phylogenetic analysis were confirmed by DNA-DNA hybridization experiments, thus demonstrating that sequence databases of defined DNA targets, such as sodA, may constitute a valuable alternative approach for modern bacterial systematics.

Native valve endocarditis due to Enterococcus hirae.

Enterococcus hirae is a rare isolate in clinical specimens. We describe a case of native aortic-valve endocarditis that was caused by Enterococcus hirae in a 72-year-old man. This is the first reported case of endocarditis due to this organism.