Implementation of an antibiotic resistance surveillance tool in Madagascar, the TSARA project: a prospective, observational, multicentre, hospital-based study protocol.

INTRODUCTION: Antimicrobial resistance (AMR) has become a significant public health threat. Without any interventions, it has been modelled that AMR will account for an estimated 10 million deaths annually by 2050, this mainly affects low/middle-income countries. AMR has a systemic negative perspective affecting the overall healthcare system down to the patient's personal outcome. In response to this issue, the WHO urged countries to provide antimicrobial stewardship programmes (ASPs). ASPs in hospitals are a vital component of national action plans for AMR, and have been shown to significantly reduce AMR, in particular in low-income countries such as Madagascar.As part of an ASP, AMR surveillance provides essential information needed to guide medical practice. We developed an AMR surveillance tool-Technique de Surveillance Actualisée de la Résistance aux Antimicrobiens (TSARA)-with the support of the Mérieux Foundation. TSARA combines bacteriological and clinical information to provide a better understanding of the scope and the effects of AMR in Madagascar, where no such surveillance tool exists. METHODS AND ANALYSIS: A prospective, observational, hospital-based study was carried out for data collection using a standardised data collection tool, called TSARA deployed in 2023 in 10 hospitals in Madagascar participating in the national Malagasy laboratory network (Réseau des Laboratoires à Madagascar (RESAMAD)). Any hospitalised patient where the clinician decided to take a bacterial sample is included. As a prospective study, individual isolate-level data and antimicrobial susceptibility information on pathogens were collected routinely from the bacteriology laboratory and compiled with clinical information retrieved from face-to-face interviews with the patient and completed using medical records where necessary. Analysis of the local ecology, resistance rates and antibiotic prescription patterns were collected. ETHICS AND DISSEMINATION: This protocol obtained ethical approval from the Malagasy Ethical Committee n°07-MSANP/SG/AGMED/CNPV/CERBM on 24 January 2023. Findings generated were shared with national health stakeholders, microbiologists, members of the RESAMAD network and the Malagasy academic society of infectious diseases.

Using a multiplex serological assay to estimate time since SARS-CoV-2 infection and past clinical presentation in malagasy patients.

Background: The world is facing a 2019 coronavirus (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this context, efficient serological assays are needed to accurately describe the humoral responses against the virus. These tools could potentially provide temporal and clinical characteristics and are thus paramount in developing-countries lacking sufficient ongoing COVID-19 epidemic descriptions. Methods: We developed and validated a Luminex xMAP® multiplex serological assay targeting specific IgM and IgG antibodies against the SARS-CoV-2 Spike subunit 1 (S1), Spike subunit 2 (S2), Spike Receptor Binding Domain (RBD) and the Nucleocapsid protein (N). Blood samples collected periodically for 12 months from 43 patients diagnosed with COVID-19 in Madagascar were tested for these antibodies. A random forest algorithm was used to build a predictive model of time since infection and symptom presentation. Findings: The performance of the multiplex serological assay was evaluated for the detection of SARS-CoV-2 anti-IgG and anti-IgM antibodies. Both sensitivity and specificity were equal to 100% (89.85-100) for S1, RBD and N (S2 had a lower specificity = 95%) for IgG at day 14 after enrolment. This multiplex assay compared with two commercialized ELISA kits, showed a higher sensitivity. Principal Component Analysis was performed on serologic data to group patients according to time of sample collection and clinical presentations. The random forest algorithm built by this approach predicted symptom presentation and time since infection with an accuracy of 87.1% (95% CI = 70.17-96.37, p-value = 0.0016), and 80% (95% CI = 61.43-92.29, p-value = 0.0001) respectively. Interpretation: This study demonstrates that the statistical model predicts time since infection and previous symptom presentation using IgM and IgG response to SARS-CoV2. This tool may be useful for global surveillance, discriminating recent- and past- SARS-CoV-2 infection, and assessing disease severity. Fundings: This study was funded by the French Ministry for Europe and Foreign Affairs through the REPAIR COVID-19-Africa project coordinated by the Pasteur International Network association. WANTAI reagents were provided by WHO AFRO as part of a Sero-epidemiological "Unity" Study Grant/Award Number: 2020/1,019,828-0 P·O 202546047 and Initiative 5% grant n°AP-5PC-2018-03-RO.

Management of patients with pulmonary mycobacteriosis in France: a multicenter retrospective cohort study.

BACKGROUND: Recent studies report very low adherence of practitioners to ATS/IDSA recommendations for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD), as well as a great variability of practices. Type of management could impact prognosis. METHODS: To evaluate management and prognosis of patients with NTM-PD cases with respect to ATS recommendations, we conducted a multicenter retrospective cohort study (18 sentinel sites distributed throughout France), over a period of six years. We collected clinical, radiological, microbiological characteristics, management and outcome of the patients (especially death or not). RESULTS: 477 patients with NTM-PD were included. Respiratory comorbidities were found in 68% of cases, tuberculosis sequelae in 31.4% of patients, and immunosuppression in 16.8% of cases. The three most common NTM species were Mycobacterium avium complex (60%), M. xenopi (20%) and M. kansasii (5.7%). Smear-positive was found in one third of NTM-PD. Nodulobronchiectatic forms were observed in 54.3% of cases, and cavitary forms in 19.1% of patients. Sixty-three percent of patients were treated, 72.4% of patients with smear-positive samples, and 57.5% of patients with smear-negative samples. Treatment was in adequacy with ATS guidelines in 73.5%. The 2-year mortality was 14.4%. In the Cox regression, treatment (HR = 0.51), age (HR = 1.02), and M. abscessus (3.19) appeared as the 3 significant independent prognostic factors. CONCLUSION: These findings highlight the adequacy between French practices and the ATS/IDSA guidelines. Treatment was associated with a better survival.

Drug-resistant TB prevalence study in 5 health institutions in Haiti.

OBJECTIVES: Tuberculosis (TB) is the leading infectious cause of death in the world. Multi-drug resistant TB (MDR-TB) is a major public health problem as treatment is long, costly, and associated to poor outcomes. Here, we report epidemiological data on the prevalence of drug-resistant TB in Haiti. METHODS: This cross-sectional prevalence study was conducted in five health centers across Haiti. Adult, microbiologically confirmed pulmonary TB patients were included. Molecular genotyping (rpoB gene sequencing and spoligotyping) and phenotypic drug susceptibility testing were used to characterize rifampin-resistant MTB isolates detected by Xpert MTB/RIF. RESULTS: Between April 2016 and February 2018, 2,777 patients were diagnosed with pulmonary TB by Xpert MTB/RIF screening and positive MTB cultures. A total of 74 (2.7%) patients were infected by a drug-resistant (DR-TB) M. tuberculosis strain. Overall HIV prevalence was 14.1%. Patients with HIV infection were at a significantly higher risk for infection with DR-TB strains compared to pan-susceptible strains (28.4% vs. 13.7%, adjusted odds ratio 2.6, 95% confidence interval 1.5-4.4, P = 0.001). Among the detected DR-TB strains, T1 (29.3%), LAM9 (13.3%), and H3 (10.7%) were the most frequent clades. In comparison with previous spoligotypes studies with data collected in 2000-2002 and in 2008-2009 on both sensitive and resistant strains of TB in Haiti, we observed a significant increase in the prevalence of the drug-resistant MTB Spoligo-International-Types (SIT) 137 (X2 clade: 8.1% vs. 0.3% in 2000-02 and 0.9% in 2008-09, p<0.001), 5 (T1 clade: 6.8% vs 1.9 in 2000-02 and 1.7% in 2008-09, P = 0.034) and 455 (T1 clade: 5.4% vs 1.6% and 1.1%, P = 0.029). Newly detected spoligotypes (SIT 6, 7, 373, 909 and 1624) were also recorded. CONCLUSION: This study describes the genotypic and phenotypic characteristics of DR-TB strains circulating in Haiti from April 2016 to February 2018. Newly detected MTB clades harboring multi-drug resistance patterns among the Haitian population as well as the higher risk of MDR-TB infection in HIV-positive people highlights the epidemiological relevance of these surveillance data. The importance of detecting RIF-resistant patients, as proxy for MDR-TB in peripheral sites via molecular techniques, is particularly important to provide adequate patient case management, prevent the transmission of resistant strains in the community and to contribute to the surveillance of resistant strains.

Prevalence, Risk Factors, and Genetic Characterization of Extended-Spectrum Beta-Lactamase Escherichia coli Isolated From Healthy Pregnant Women in Madagascar.

Antimicrobial resistance is a major public health concern worldwide affecting humans, animals and the environment. However, data is lacking especially in developing countries. Thus, the World Health Organization developed a One-Health surveillance project called Tricycle focusing on the prevalence of ESBL-producing Escherichia coli in humans, animals, and the environment. Here we present the first results of the human community component of Tricycle in Madagascar. From July 2018 to April 2019, rectal swabs from 492 pregnant women from Antananarivo, Mahajanga, Ambatondrazaka, and Toamasina were tested for ESBL-E. coli carriage. Demographic, sociological and environmental risk factors were investigated, and E. coli isolates were characterized (antibiotic susceptibility, resistance and virulence genes, plasmids, and genomic diversity). ESBL-E. coli prevalence carriage in pregnant women was 34% varying from 12% (Toamasina) to 65% (Ambatondrazaka). The main risk factor associated with ESBL-E. coli carriage was the rainy season (OR = 2.9, 95% CI 1.3-5.6, p = 0.009). Whole genome sequencing was performed on 168 isolates from 144 participants. bla CTX-M-15 was the most frequent ESBL gene (86%). One isolate was resistant to carbapenems and carried the bla NDM-5 gene. Most isolates belonged to commensalism associated phylogenetic groups A, B1, and C (90%) and marginally to extra-intestinal virulence associated phylogenetic groups B2, D and F (10%). Multi locus sequence typing showed 67 different sequence types gathered in 17 clonal complexes (STc), the most frequent being STc10/phylogroup A (35%), followed distantly by the emerging STc155/phylogroup B1 (7%), STc38/phylogroup D (4%) and STc131/phylogroup B2 (3%). While a wide diversity of clones has been observed, SNP analysis revealed several genetically close isolates (n = 34/168) which suggests human-to-human transmissions. IncY plasmids were found with an unusual prevalence (23%), all carrying a bla CTX-M-15. Most of them (85%) showed substantial homology (≥85%) suggesting a dissemination of IncY ESBL plasmids in Madagascar. This large-scale study reveals a high prevalence of ESBL-E. coli among pregnant women in four cities in Madagascar associated with warmth and rainfall. It shows the great diversity of E. coli disseminating throughout the country but also transmission of specific clones and spread of plasmids. This highlights the urgent need of public-health interventions to control antibiotic resistance in the country.

First genetic characterisation of multidrug-resistant Mycobacterium tuberculosis isolates from Algeria.

OBJECTIVES: To characterise the genotypes of multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) isolated in Algeria, where there is a low MDR-MTB incidence rate. METHODS: Ten MDR isolates and one resistant to isoniazid were investigated by PCR-Sanger sequencing for 10 loci involved in resistance. Amplicon-based next generation sequencing (NGS) of 15 loci was additionally performed on isolates harbouring novel mutations. RESULTS: Sanger and amplicon-NGS provided the same results as with GenoType kits. Mutations known to be associated with resistance were described for most isolates: rpoB S531L in seven of 10 rifampicin-R MTB isolates, katG S315T in nine of 11 isoniazid-R, and promoter inhA c-15t in three of 11, embB M306V or M306I in two of two ethambutol-R, rpsL K43R in four of eight or rrs a514c associated with gidB L16R in streptomycin-R, gyrA A90V in the ofloxacin-R pre-XDR isolate. New and rare mutations were also described in rpoB (deletion 512-513-514), katG (S315R, M126I/ R496L), gidB (V124G, E92A, V139A, G37V), and gyrA (P8A). Mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) profiles were similar for three isolates (lineage Cameroon), indicating a possible clonal diffusion in epidemiologically unrelated patients. CONCLUSIONS: Resistant MTB isolates in Algeria harbour resistance genotypes similar to other countries, but some rare patterns may result from selection and transmission processes inherent to the country.

Mycobacterium bolletii Lung Disease in Cystic Fibrosis.

BACKGROUND: The cystic fibrosis (CF) pathogen, Mycobacterium abscessus complex, covers three subspecies: M. abscessus, M. massiliense, and M. bolletii. There are no clinical outcome data concerning M. bolletii. Our aim was to characterize M. bolletii lung infections in patients with CF. METHODS: We included patients with M. bolletii lung infection recorded between 1994 and 2012 in France. Data were collected from the CF registry, medical records, and questionnaires submitted to the CF primary physician. Strains were typed by multilocus sequence typing analysis. RESULTS: Fifteen cases were identified in nine CF centers. Nine patients (60%) presented with nontuberculous mycobacterial pulmonary disease. Follow-up of 13 patients showed a trend to more rapid decline in FEV1 in the first year of colonization (-9.4%; SD 19.3) in comparison with noninfected control subjects (-2.3%; SD 12.1) (P = .16). Twelve patients were treated, and 11 received oral macrolides. Treatment-induced eradication occurred in five patients (41.7%). Four patients died (26.7%), including one patient with fatal nontuberculous mycobacterial pulmonary disease. Inducible macrolide resistance was demonstrated in all strains. Patients always harbored unique strains. CONCLUSIONS: Our study reports the largest study cohort of CF patients infected with M. bolletii. M. bolletii infection affects both children and young adults, is most often symptomatic, and may be fatal. Macrolide-based therapies have poor effectiveness. There is no evidence of patient-to-patient transmission.

Clinical characteristics, risk factors, and outcome of tuberculosis in kidney transplant recipients: A multicentric case-control study in a low-endemic area.

OBJECTIVES: Tuberculosis (TB) is a rare but life-threatening infection after solid organ transplant. The present study was undertaken to assess the clinical features, risk factors, and outcome of TB after kidney transplantation in a low-prevalence area. METHODS: We conducted a retrospective study, describing all kidney transplant recipients diagnosed with TB between 2005 and 2015 in 3 French centers. For each TB case, 2 controls without TB were identified and matched by center, age, transplant date, and birth country. Risk factors associated with TB were identified and survival estimated. RESULTS: Thirty-two cases and 64 control patients were included among 3974 transplantations. The prevalence of TB was 0.83%. Median age at the time of diagnosis was 64 years; 75% were born in a high TB prevalence country, but only 3 had received isoniazid prophylaxis for latent TB infection. TB occurred at a median of 22 months after transplantation. On diagnosis, 66% had disseminated infection. Median duration of treatment was 9 months. Immunosuppressive therapy changes were necessary in all patients because of drug-drug interactions. Among cases, 5 deaths occurred during follow-up (median duration: 41 months), one directly related with TB. Survival was significantly lower in transplant recipients with TB, as compared to controls (P = .001). No predictive factors of tuberculosis after transplantation were statistically significant in univariate analysis. CONCLUSION: TB in kidney transplant recipients is a rare and late event, but is associated with significantly reduced survival. Our results emphasize the need for systematic screening for LTBI, followed by IPT in high-risk patients.

Comparison of Saramis 4.12 and IVD 3.0 Vitek MS Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry for Identification of Mycobacteria from Solid and Liquid Culture Media.

During the last decade, many investigators have studied matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for identification of mycobacteria. Diverse and contradictory results indicated that optimal level for routine testing has not been reached yet. This work aimed to assess Vitek MS through two distinct versions, Saramis v4.12 RUO and the IVD v3.0, under conditions close to routine laboratory practice. Overall, 111 mycobacterial isolates were subjected to protein extraction and same spectra were matched against both databases. The IVD v3.0 database proved to be superior to Saramis v4.12 and its identification rates remarkably increased, from 67% to 94% for isolates grown on Middlebrook 7H10 solid medium and from 62% to 91% for isolates grown on mycobacterial growth indicator tube (MGIT) liquid medium. With this new version, IVD v3.0, MALDI-TOF MS might be integrated into routine clinical diagnostics, although molecular techniques remain mandatory in some cases.

Evaluation of the new GenoType NTM-DR kit for the molecular detection of antimicrobial resistance in non-tuberculous mycobacteria.

Objectives: Non-tuberculous mycobacteria (NTM) are emerging pathogens causing difficult-to-treat infections. We tested a new assay (GenoType NTM-DR) that detects natural and acquired resistance mechanisms to macrolides and aminoglycosides in frequently isolated NTM species. Methods: Performance was assessed on 102 isolates including reference strains [16 Mycobacterium avium , 10 Mycobacterium intracellulare , 8 Mycobacterium chimaera , 15 Mycobacterium chelonae and 53 Mycobacterium abscessus (including subsp. abscessus isolates, 18 with a t28 in erm(41) and 10 with a c28, 13 subsp. bolletii isolates and 12 subsp. massiliense isolates)]. Genotypes were determined by PCR sequencing of erm(41) and rrl for clarithromycin resistance and of the 1400-1480 rrs region for aminoglycoside resistance. Phenotypes were determined by MIC microdilution. Results: GenoType NTM-DR yielded results concordant with Sanger sequencing for 100/102 (98%) isolates. The erm(41) genotypic pattern was accurately identified for M. abscessus isolates . Mutations in rrl were detected in 15 isolates (7 M. avium complex, 5 M. abscessus and 3 M. chelonae ) with acquired clarithromycin resistance harbouring rrl mutations (a2057c, a2058g, a2058t or a2059c). Mutations in rrs were detected in five isolates with amikacin resistance harbouring the rrs mutation a1408g. In two isolates, the NTM-DR test revealed an rrl mutation (initial sequencing being WT), which was confirmed by re-sequencing. The test results were concordant with phenotypic susceptibility testing in 96/102 (94.1%) isolates, with four clarithromycin-resistant and two amikacin-resistant isolates not harbouring mutations. Conclusions: The GenoType NTM-DR test is efficient in detecting mutations predictive of antimicrobial resistance in M. avium complex, M. abscessus and M. chelonae.

Selection of Resistance to Clarithromycin in Mycobacterium abscessus Subspecies.

Mycobacterium abscessus is an emerging pathogen against which clarithromycin is the main drug used. Clinical failures are commonly observed and were first attributed to acquired mutations in rrl encoding 23S rRNA but were then attributed to the intrinsic production of the erm(41) 23S RNA methylase. Since strains of M. abscessus were recently distributed into subspecies and erm(41) sequevars, we investigated acquired clarithromycin resistance mechanisms in mutants selected in vitro from four representative strains. Mutants were sequenced for rrl, erm(41), whiB, rpIV, and rplD and studied for seven antibiotic MICs. For mutants obtained from strain M. abscessus subsp. abscessus erm(41) T28 sequevar and strain M. abscessus subsp. bolletii, which are both known to produce effective methylase, rrl was mutated in only 19% (4/21) and 32.5% (13/40) of mutants, respectively, at position 2058 (A2058C, A2058G) or position 2059 (A2059C, A2059G). No mutations were observed in any of the other genes studied, and resistance to other antibiotics (amikacin, cefoxitin, imipenem, tigecycline, linezolid, and ciprofloxacin) was mainly unchanged. For M. abscessus subsp. abscessus erm(41) C28 sequevar and M. abscessus subsp. massiliense, not producing effective methylase, 100% (26/26) and 97.5% (39/40) of mutants had rrl mutations at position 2058 (A2058C, A2058G, A2058T) or position 2059 (A2059C, A2059G). The remaining M. abscessus subsp. massiliense mutant showed an 18-bp repeat insertion in rpIV, encoding the L22 protein. Our results showed that acquisition of clarithromycin resistance is 100% mediated by structural 50S ribosomal subunit mutations for M. abscessus subsp. abscessus erm(41) C28 and M. abscessus subsp. massiliense, whereas it is less common for M. abscessus subsp. abscessus erm(41) T28 sequevar and M. abscessus subsp. bolletii, where other mechanisms may be responsible for failure.

Infections caused by Mycobacterium abscessus: epidemiology, diagnostic tools and treatment.

INTRODUCTION: Mycobacterium abscessus is an emerging mycobacteria that is responsible for lung diseases and healthcare-associated extrapulmonary infections. Recent findings support its taxonomic status as a single species comprising 3 subspecies designated abscessus, bolletii and massiliense. We performed a review of English-language publications investigating all three of these subspecies. Areas covered: Worldwide, human infections are often attributable to environmental contamination, although the isolation of M. abscessus in this reservoir is very rare. Basic research has demonstrated an association between virulence and cell wall components and cording, and genome analysis has identified gene transfer from other bacteria. The bacteriological diagnosis of M. abscessus is based on innovative tools combining molecular biology and mass spectrometry. Genotypic and phenotypic susceptibility testing are required to predict the success of macrolide (clarithromycin or azithromycin)-based therapeutic regimens. Genotyping methods are helpful to assess relapse and cross-transmission and to search for a common source. Treatment is not standardised, and outcomes are often unsatisfactory. Expert commentary: M. abscessus is still an open field in terms of clinical and bacteriological research. Further knowledge of its ecology and transmission routes, as well as host-pathogen interactions, is required. Because the number of human cases is increasing, it is also necessary to identify more active treatments and perform clinical trials to assess standard effective regimens.

Standardized interpretation of antibiotic susceptibility testing and resistance genotyping for Mycobacterium abscessus with regard to subspecies and erm41 sequevar.

OBJECTIVES: The objective of this study was to provide standardized antibiotic susceptibility testing (AST) for Mycobacterium abscessus with regard to subspecies. METHODS: One hundred and sixty-five clinical isolates were tested for susceptibility to 15 antibiotics using a commercial microdilution method, at two reading times: (i) early reading time (ERT), when the growth control was first positive; and (ii) late reading time (LRT), of 14 days, for detecting inducible resistance. In addition, genes or mutations involved in resistance were studied [erm(41), rrl and rrs]. RESULTS: Three patterns were observed for clarithromycin: (i) MIC >16 mg/L at ERT (median 5 days) for 15 isolates [10 subsp. abscessus erm(41) sequevar T28, 3 subsp. bolletii and 2 subsp. massiliense] among which 9 harboured an a2058g/c rrl mutation; (ii) MIC ≤16 mg/L at ERT, but >16 mg/L at LRT, for 106 isolates [84 abscessus erm(41) T28 and 22 bolletii] showing intrinsic inducible resistance; and (iii) MIC ≤4 mg/L at ERT and LRT for 44 isolates [18 abscessus erm(41) C28 and 26 massiliense]. Amikacin MIC was >64 mg/L for eight isolates [five abscessus erm(41) T28, two massiliense and one bolletii] among which seven harboured the a1408g rrs mutation, but ≤64 mg/L for the remaining isolates without mutation. For the other antibiotics, only one WT pattern was observed, with cefoxitin, tigecycline and linezolid showing MIC values compatible with susceptibility. CONCLUSIONS: Standard AST can predict clarithromycin and amikacin resistance using interpretation rules with regard to subspecies. For other antibiotics, since only one pattern is observed, there is no need for systematic phenotypic or genotypic testing.

Human infections due to nontuberculous mycobacteria: the infectious diseases and clinical microbiology specialists' point of view.

Nontuberculous mycobacteria (>150 species such as Mycobacterium avium, Mycobacterium kansasii, Mycobacterium chelonae and Mycobacterium abscessus) are opportunistic pathogens causing lung and extrarespiratory infections, beside M. ulcerans and M. marinum that are pathogens causing specific skin and soft tissue infections. Disseminated infections occur only in severe immunosuppressed conditions such as AIDS. The diagnosis is based on repeated isolations of the same mycobacterium associated with clinical and radiological signs, and the absence of tuberculosis. Precise species identification is obtained by molecular biology. Therapeutic antibiotic regimens differ with regard to the mycobacterial species that are involved. Prevention of iatrogenic infections relies on using sterile water in all injections, healthcare and cosmetic occupations. Future perspectives are to set effective antibiotic regimens tested in randomized therapeutic trials.

A case of postoperative breast infection by Mycobacterium fortuitum associated with the hospital water supply.

This report describes the first known laboratory-confirmed case of Mycobacterium fortuitum breast infection related to the hospital water supply. The source of the M fortuitum infection was identified by repetitive extragenic palindromic sequence-based polymerase chain reaction genotyping. In addition, we discuss appropriate infection control measures to minimize patient exposure to waterborne pathogens, in particular, in the context of nontuberculous mycobacteria, which is difficult to eradicate from the water supply network.

Classification algorithm for subspecies identification within the Mycobacterium abscessus species, based on matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Mycobacterium abscessus, as a species, has been increasingly implicated in respiratory infections, notably in cystic fibrosis patients. The species comprises 3 subspecies, which can be difficult to identify. Since they differ in antibiotic susceptibility and clinical relevance, developing a routine diagnostic tool discriminating Mycobacterium abscessus at the subspecies level is a real challenge. Forty-three Mycobacterium abscessus species isolates, previously identified by multilocus sequence typing, were analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A subspecies identification algorithm, based on five discriminating peaks, was drawn up and validated by blind identification of a further 49 strains, 94% of which (n = 46) were correctly identified. Two M. abscessus subsp. massiliense strains were misidentified as M. abscessus subsp. abscessus, and for 1 other strain identification failed. Inter- and intralaboratory reproducibility tests were conclusive. This study presents, for the first time, a classification algorithm for MALDI-TOF MS identification of the 3 M. abscessus subspecies. MALDI-TOF MS proved effective in discriminating within the M. abscessus species and might be easily integrated into the workflow of microbiology labs.

Clonal relationship and differentiation among Mycobacterium abscessus isolates as determined using the semiautomated repetitive extragenic palindromic sequence PCR-based DiversiLab system.

Mycobacterium abscessus is a rapidly growing mycobacterium that causes respiratory tract infections in predisposed patients, such as those with cystic fibrosis and nosocomial skin and soft tissue infections. In order to investigate the clonal relationships between the strains causing epidemic episodes, we evaluated the discriminatory power of the semiautomated DiversiLab (DL) repetitive extragenic palindromic sequence PCR (REP-PCR) test for M. abscessus genotyping. Since M. abscessus was shown to be composed of subspecies (M. abscessus subsp. massiliense, M. abscessus subsp. bolletii, and M. abscessus subsp. abscessus), we also evaluated the ability of this technique to differentiate subspecies. The technique was applied to two collections of clinical isolates, (i) 83 M. abscessus original isolates (43 M. abscessus subsp. abscessus, 12 M. abscessus subsp. bolletii, and 28 M. abscessus subsp. massiliense) from infected patients and (ii) 35 repeated isolates obtained over 1 year from four cystic fibrosis patients. The DL REP-PCR test was standardized for DNA extraction, DNA amplification, and electrophoresis pattern comparisons. Among the isolates from distinct patients, 53/83 (62%) isolates showed a specific pattern, and 30 were distributed in 11 clusters and 6 patterns, with 2 to 4 isolates per pattern. The clusters and patterns did not fully correlate with multilocus sequence typing (MLST) analysis results. This revealed a high genomic diversity between patients, with a discriminatory power of 98% (Simpson's diversity index). However, since some isolates shared identical patterns, this raises the question of whether it is due to transmission between patients or a common reservoir. Multiple isolates from the same patient showed identical patterns, except for one patient infected by two strains. Between the M. abscessus subspecies, the indexes were <70%, indicating that the DL REP-PCR test is not an accurate tool for identifying organisms to the subspecies level. REP-PCR appears to be a rapid genotyping method that is useful for investigating epidemics of M. abscessus infections.

Xpert GBS assay for rapid detection of group B streptococcus in gastric fluid samples from newborns.

The Xpert GBS real-time PCR assay was applied to gastric fluid samples from 143 newborns, and it detected group B streptococcus (GBS) within 1 h for 16 (11.2%) cases, while microscopic examination detected only 2 cases. The sensitivity and specificity of the Xpert GBS were 80% and 100%, respectively, with regard to 20 cases of GBS colonization or infection. Concordance of Xpert GBS results versus culture was 92.3%. This test detects in a timely manner newborns at risk for invasive GBS disease.

Evaluation of the ßLacta test, a rapid test detecting resistance to third-generation cephalosporins in clinical strains of Enterobacteriaceae.

For decades, third-generation cephalosporins (3GC) have been major drugs used to treat infections due to Enterobacteriaceae; growing resistance to these antibiotics makes the rapid detection of such resistance important. The ßLacta test is a chromogenic test developed for detecting 3GC-resistant isolates from cultures on solid media within 15 min. A multicenter prospective study conducted in 5 French and Belgian hospitals evaluated the performance of this test on clinical isolates. Based on antibiotic susceptibility testing, strains resistant or intermediate to cefotaxime or ceftazidime were classified as 3GC resistant, and molecular characterization of this resistance was performed. The rates of 3GC resistance were 13.9% (332/2,387) globally, 9.4% in Escherichia coli (132/1,403), 25.6% in Klebsiella pneumoniae (84/328), 30.3% in species naturally producing inducible AmpC beta-lactamases (109/360), and 5.6% in Klebsiella oxytoca and Citrobacter koseri (7/124). The sensitivities and specificities of the ßLacta test were, respectively, 87.7% and 99.6% overall, 96% and 100% for E. coli and K. pneumoniae, and 67.4% and 99.6% for species naturally producing inducible AmpC beta-lactamase. False-negative results were mainly related to 3GC-resistant strains producing AmpC beta-lactamase. Interestingly, the test was positive for all 3GC-resistant extended-spectrum beta-lactamase-producing isolates (n = 241). The positive predictive value was 97% and remained at ≥96% for prevalences of 3GC resistance ranging between 10 and 30%. The negative predictive values were 99% for E. coli and K. pneumoniae and 89% for the species producing inducible AmpC beta-lactamase. In conclusion, the ßLacta test was found to be easy to use and efficient for the prediction of resistance to third-generation cephalosporins, particularly in extended-spectrum beta-lactamase-producing strains.