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Mycobacterium avium isolates resistant to clarithromycin and azithromycin have been recovered from patients undergoing antibiotic therapy. Comparison of DNA fingerprints of sensitive and resistant isolates showed that resistance resulted from mutation of the original, sensitive isolate in five of seven patients. In the other two patients, the clarithromycin-resistant isolates were unrelated to the sensitive isolate, suggesting that the resistant isolate resulted from either superinfection or selection of a resistant strain from a polyclonal population. Investigation of the mechanisms of clarithromycin and azithromycin resistance in M. avium showed that high-level resistance resulted from a point mutation at position A-2058 in the 23S rRNA. Based on this finding, a rapid screen for clarithromycin-resistance in M. avium was developed based on PCR. Twenty-three clinical isolates were analyzed, seven of which were clarithromycin-resistant. The target product was amplified only in clarithromycin-resistant strains, all of which had mutations at position 2058. A polyuridylic acid (poly U)-dependent in vitro translation system from M. avium was developed to investigate the effect of antibiotics on protein synthesis. Clarithromycin was an effective inhibitor of protein synthesis in cell-free extracts of a susceptible M. avium strain, whereas a high-level resistant strain was less susceptible to clarithromycin in vitro. Mixtures of extracts from sensitive and resistant strains showed a pattern of clarithromycin inhibition similar to the resistant strain, suggesting that resistance may be dominant in partial diploids. Three M. avium strains exhibiting step-wise, intermediate resistance to azithromycin were characterized in comparison to the sensitive parent. All strains were similar in hydrophobicity, growth medium requirements, and growth response to temperature. The azithromycin-resistant strains were resistant to several unrelated agents, including ciprofloxacin, rifabutin, and ethidium bromide. Addition of carbonyl cyanide m-chlorophenylhydrazone (CCCP) did not lower minimal inhibitory concentrations (MICs) for ciprofloxacin or ethidium bromide. Cell-free extracts of the strains were as sensitive to azithromycin in vitro as the parent strain. The results rule out inactivation, efflux, and mutations in the target as resistance mechanisms, and suggest intermediate resistance may be due to altered permeability of the cell wall or membrane. / Ph. D.

Claritromicina e clofazimina têm sido utilizadas no tratamento da hanseníase e tuberculose e também em infecções pelo complexo Mycobacterium avium, complicação comum em pacientes que se encontram em estágios avançados da síndrome da imunodeficiência adquirida (SIDA). Como os dados sobre a toxicidade de esquemas terapêuticos que incluem estes fármacos são escassos, o presente estudo teve como objetivo determinar os efeitos adversos destas terapias, por meio da avaliação dos parâmetros hematológicos, hemostáticos e bioquímicos e a correlação destes parâmetros com as doses testadas e destas com a concentração plasmática dos medicamentos administrados, intraperitonealmente, em ratos machos Wistar, em monoterapia, em regime de doses única (50, 100 e 200mg/kg de peso) e múltipla (100mg/kg). Clofazimina, em regime de dose única, provocou aumento no número de eritrócitos e redução dos índices eritrocitométricos VCM e CHCM. Em regime de dose múltipla, claritromicina provocou aumento de leucócitos e de células mono e polimorfonucleares. Ambos os fármacos, em dose única, parecem inverter a proporção entre células mono e polimorfonucleares. Foi observado aumento do número de células polimorfonucleares e células em degeneração, ocasionados tanto por clofazimina como pela claritromicina. Em regime de dose única, clofazimina e claritromicina prolongaram o TP. Claritromicina, quando administrada em dose múltipla, causou este mesmo efeito e também o prolongamento do TTPA. Os resultados da avaliação da função hepática mostraram resultados inconclusivos com relação às dosagens de AST, ALT e fosfatase alcalina, porém, foi observado aumento dos níveis plasmáticos de ?-GT provocado pela clofazimina, em regime de dose única. Claritromicina induziu aumento dos níveis de ?-GT, em regime de doses única e múltipla, e provocou elevação de bilirrubinas total e direta, em dose única. Houve aumento das concentrações plasmáticas dos fármacos à medida que as doses administradas aumentaram, apesar da claritromicina exibir um comportamento farmacocinético não-linear. Portanto, clofazimina e claritromicina provocam alterações hematológicas, hemostáticas e bioquímicas e os resultados de concentração plasmática são valiosos para avaliação de efeitos adversos em estudos comparativos de monoterapia e associação entre os medicamentos. / Clarithromycin and clofazimine have been used to treat leprosy and tuberculosis as well as infections of Mycobacterium avium complex, an ordinary complication in patients who are in advanced stage of Acquired Immunodeficiency Syndrome (AIDS). As the data about the toxicity of therapeutic schemes including those drugs are scarce, this research had the aim to determine the adverse effects of those therapies, through the evaluation of hematological, hemostatic and biochemical parameters and the relationship between these parameters and doses tested and between doses and plasma concentrations of drugs administered intraperitoneally, in male Wistar rats, in monotherapy, in single (50, 100 and 200mg/kg body wt), and multiple (100mg/kg body wt) doses regime. Clofazimine, in single dose regime, increased the number of erythrocytes, and it decreased the red cells indices MCV and MCHC. In multiple dose regime, clarithromycin increased the number of leukocytes and mononuclear and polymorphonuclear cells. Both the drugs, in single dose, seem to invert the proportion between mononuclear and polymorphonuclear cells. It was observed an increase in the number of polymorphonuclear cells and cells under degeneration caused by clofazimine and clarithromycin. In single dose regime, clofazimine and clarithromycin prolonged PT. When clarithromycin was administered in multiple dose, it brought about this same effect and also it prolonged aPTT. The results of hepatic function evaluation showed inconclusive results about AST, ALT and alkaline phosphatase levels, but it was observed an increase of U-GGT plasma levels provoked by clofazimine, in single dose regime. Clarithromycin brought about an increase of U-GGT plasma levels, in single and multiple dose regime, and caused an increase of total and direct bilirrubin, in single dose. An increase of plasma concentration of drugs was observed as administered doses were increased, though clarithromycin has nonlinear pharmacokinetics behavior. Therefore, clofazimine and clarithromycin induce hematological, hemostatic and biochemical alterations and the results of plasmatic concentration are valuable to evaluate adverse effects in comparative research of monotherapy and association between drugs.

Σκοπός της παρούσας μελέτης ήταν η διερεύνηση της εξωκυττάριας συγκέντρωσης και του βαθμού διεισδυτικότητας των νεότερων μακρολίδων στο υγρό περιεχόμενο του ιγμορείου άντρου, εντός των πρώτων 24 ωρών από την χορήγηση σε ασθενείς με οξεία παραρρινοκολπίτιδα, χρησιμοποιώντας ως μοντέλα την κλαριθρομυκίνη και αζιθρομυκίνη. Σε 36 ασθενείς με οξεία ιγμορίτιδα συλλέχθηκαν δείγματα υγρού από το ιγμόρειο άντρο και ορού αίματος 2,4,6,8 και 12 ώρες ή 2,6,12 και 24 ώρες μετά την χορήγηση τριών δόσεων ρ.ο. κλαριθρομυκίνης 500 mg δις ημερησίως ή δύο δόσεων ρ.ο. αζιθρομυκίνης 500 mg άπαξ ημερησίως αντίστοιχα. Οι συγκεντρώσεις των φαρμάκων στα δυο βιολογικά υγρά προσδιορίσθηκαν με την υγρή χρωματογραφία υψηλής απόδοσης με φθοριομετρική ανίχνευση, ενώ επίσης εκτιμήθηκε το pH σε όλα τα δείγματα υγρού παραρρίνιων. Η μέση συγκέντρωση κλαριθρομυκίνης στο υγρό παραρρίνιων κόλπων ήταν σημαντικά υψηλότερη από την αντίστοιχη της αζιθρομυκίνης (2,47 mg/l έναντι 0,65 mg/l), ενώ ο μέσος βαθμός διεισδυτικότητας στο υγρό του ιγμόρειου άντρου,εκφρασμένος ως η αναλογία των συγκεντρώσεων φαρμάκου στον ιστό και στον ορό αίματος, ήταν παρόμοια για τα δύο αντιβιοτικά (115 % και 120% αντίστοιχα). Σε ασθενείς με οξεία παραρρινοκολπίτιδα, η κλαριθρομυκίνη και η αζιθρομυκίνη παρουσιάζουν επαρκή διεισδυτικότητα στο υγρό του ιγμόρειου άντρου για την εκρίζωση στελεχών streptococcus pneumoniae ευαίσθητων στην ερυθρομυκίνη. Με βάση τις συγκρίσιμες δραστικότητες τους in vitro, την επίδραση του pH του υγρού του ιγμόρειου άντρου και το προφίλ διεισδυτικότητας στο συγκεκριμένο υγρό, συμπεραίνουμε ότι ανάμεσα στα ευαίσθητα στην ερυθρομυκίνη στελέχη streptococcus pneumoniae, η κλαριθρομυκίνη θα πλεονεκτούσε σε σχέση με την αζιθρομυκίνη στην εκρίζωση των στελεχών χαμηλής αντίστασης. / The aim of this study was to investigate the extracellular concentration and the degree of sinus fluid penetration of newer macrolides, during the first 24-48 hours of treatment in patients with acute bacterial rhinosinusitis (ABRS), choosing clarithromycin and azithromycin as model antibiotics. An open, noninterventional pharmacokinetic study was performed at a tertiary teaching hospital. In 36 outpatients with ABRS, sinus fluid aspirates and serum samples were collected 2, 4, 6, 8 and 12 hours or 2, 6, 12 and 24 hours after the administration of three doses of oral clarithromycin, 500mg, twice daily or two doses of oral azithromycin, 500 mg, once daily, respectively. Drug concentrations were determined in both matrices by high-performance liquid chromatography (HPLC) with fluorometric detection ,and the pH was estimated for all sinus fluid samples. The average clarithromycin sinus fluid concentration was found to be significantly higher than the corresponding azithromycin concentration (2.47mg/L versus 0.65 mg/L), while the extent of the average sinus fluid penetration, expressed by the ratio of drug concentration in tissue versus serum, was similar for both drugs (115% and 120% respectively). In patients with ABRS, clarithromycin and azithromycin, present adequate penetration into sinus fluid to eradicate erythromycin-sensitive strains of S. pneumoniae. Considering their comparative in vitro activity, the sinus fluid pH effect and their sinus fluid penetration profile, we may conclude that among the erythromycin-resistant S. pneumoniae strains, clarithromycin might be advantageous over azithromycin in eradicating some of the low-level resistant strains.

Claritromicina e clofazimina têm sido utilizadas no tratamento da hanseníase e tuberculose e também em infecções pelo complexo Mycobacterium avium, complicação comum em pacientes que se encontram em estágios avançados da síndrome da imunodeficiência adquirida (SIDA). Como os dados sobre a toxicidade de esquemas terapêuticos que incluem estes fármacos são escassos, o presente estudo teve como objetivo determinar os efeitos adversos destas terapias, por meio da avaliação dos parâmetros hematológicos, hemostáticos e bioquímicos e a correlação destes parâmetros com as doses testadas e destas com a concentração plasmática dos medicamentos administrados, intraperitonealmente, em ratos machos Wistar, em monoterapia, em regime de doses única (50, 100 e 200mg/kg de peso) e múltipla (100mg/kg). Clofazimina, em regime de dose única, provocou aumento no número de eritrócitos e redução dos índices eritrocitométricos VCM e CHCM. Em regime de dose múltipla, claritromicina provocou aumento de leucócitos e de células mono e polimorfonucleares. Ambos os fármacos, em dose única, parecem inverter a proporção entre células mono e polimorfonucleares. Foi observado aumento do número de células polimorfonucleares e células em degeneração, ocasionados tanto por clofazimina como pela claritromicina. Em regime de dose única, clofazimina e claritromicina prolongaram o TP. Claritromicina, quando administrada em dose múltipla, causou este mesmo efeito e também o prolongamento do TTPA. Os resultados da avaliação da função hepática mostraram resultados inconclusivos com relação às dosagens de AST, ALT e fosfatase alcalina, porém, foi observado aumento dos níveis plasmáticos de ?-GT provocado pela clofazimina, em regime de dose única. Claritromicina induziu aumento dos níveis de ?-GT, em regime de doses única e múltipla, e provocou elevação de bilirrubinas total e direta, em dose única. Houve aumento das concentrações plasmáticas dos fármacos à medida que as doses administradas aumentaram, apesar da claritromicina exibir um comportamento farmacocinético não-linear. Portanto, clofazimina e claritromicina provocam alterações hematológicas, hemostáticas e bioquímicas e os resultados de concentração plasmática são valiosos para avaliação de efeitos adversos em estudos comparativos de monoterapia e associação entre os medicamentos. / Clarithromycin and clofazimine have been used to treat leprosy and tuberculosis as well as infections of Mycobacterium avium complex, an ordinary complication in patients who are in advanced stage of Acquired Immunodeficiency Syndrome (AIDS). As the data about the toxicity of therapeutic schemes including those drugs are scarce, this research had the aim to determine the adverse effects of those therapies, through the evaluation of hematological, hemostatic and biochemical parameters and the relationship between these parameters and doses tested and between doses and plasma concentrations of drugs administered intraperitoneally, in male Wistar rats, in monotherapy, in single (50, 100 and 200mg/kg body wt), and multiple (100mg/kg body wt) doses regime. Clofazimine, in single dose regime, increased the number of erythrocytes, and it decreased the red cells indices MCV and MCHC. In multiple dose regime, clarithromycin increased the number of leukocytes and mononuclear and polymorphonuclear cells. Both the drugs, in single dose, seem to invert the proportion between mononuclear and polymorphonuclear cells. It was observed an increase in the number of polymorphonuclear cells and cells under degeneration caused by clofazimine and clarithromycin. In single dose regime, clofazimine and clarithromycin prolonged PT. When clarithromycin was administered in multiple dose, it brought about this same effect and also it prolonged aPTT. The results of hepatic function evaluation showed inconclusive results about AST, ALT and alkaline phosphatase levels, but it was observed an increase of U-GGT plasma levels provoked by clofazimine, in single dose regime. Clarithromycin brought about an increase of U-GGT plasma levels, in single and multiple dose regime, and caused an increase of total and direct bilirrubin, in single dose. An increase of plasma concentration of drugs was observed as administered doses were increased, though clarithromycin has nonlinear pharmacokinetics behavior. Therefore, clofazimine and clarithromycin induce hematological, hemostatic and biochemical alterations and the results of plasmatic concentration are valuable to evaluate adverse effects in comparative research of monotherapy and association between drugs.

Submitted by NAIRA MARIA REBELATTO BECHARA ANDERE null (nairaandere@hotmail.com) on 2016-01-25T17:55:36Z No. of bitstreams: 1 DISSERTAÇÃO VERSÃO BIBLIOTECA 2.pdf: 565381 bytes, checksum: 5dd2c824058fd7cf7771ace43cb0c34a (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-01-27T12:03:13Z (GMT) No. of bitstreams: 1 andere_nmrb_me_prud_par.pdf: 311280 bytes, checksum: 666ddf37e738a3ca488e4b697c9c212f (MD5) / Made available in DSpace on 2016-01-27T12:03:13Z (GMT). No. of bitstreams: 1 andere_nmrb_me_prud_par.pdf: 311280 bytes, checksum: 666ddf37e738a3ca488e4b697c9c212f (MD5) Previous issue date: 2016-01-07 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O presente estudo clínico controlado randomizado teve como objetivo avaliar a resposta clínica periodontal e os possíveis efeitos adversos da utilização da claritromicina (CLM) associada à terapia mecânica periodontal no tratamento de pacientes com periodontite agressiva generalizada. Para tal, foram selecionados 40 pacientes apresentando periodontite agressiva generalizada que foram distribuídos aleatoriamente, dentro de dois grupos: grupo claritromicina com 20 indivíduos que receberam RAR associado à claritromicina (500 mg – 12/12 horas) durante 3 dias; grupo placebo com 20 indivíduos que receberam RAR associado ao placebo. Foram avaliados profundidade de sondagem (PS), ganho de nível de inserção clínica (NIC) e sangramento à sondagem no baseline, 3 e 6 meses após o procedimento. Quanto aos resultados, ambos os tratamentos obtiveram melhorias clínicas em relação ao baseline, com diferença estatisticamente significativa apenas para redução em PS à favor do grupo claritromicina. Concluímos que o uso da claritromicina associado à terapia mecânia mostra-se superior à terapia padrão ouro para o tratamento de periodontite agressiva generalizada. / The present randomized, clinical trial aimed to assess the periodontal clinical response and the possible adverse effects of the clarithromycin combined to periodontal mechanical therapy in the treatment of patients with generalized aggressive periodontitis. To this, 40 patients were select and randomly assigned into two groups: Group clatithromycin with 20 subjects received SRP associated with clarithromycin (500 mg – 12/12 hours) for 3 days; group placebo with 20 subjects received SRP associated with placebo. Probing depth (PD), gain in clinical attachment level (CAL) and bleeding probing were evaluated at baseline, 3 and 6 months post- operatively. As results, both treatments had clinical benefits better than baseline, just differing statistically to PD reduction for the clarithromycin group. It may be concluded that the use of clarithromycin associated with mechanical treatment is better than the gold standard for the treatment of generalized aggressive periodontitis.

京都大学 / 0048 / 新制・課程博士 / 博士(社会健康医学) / 甲第22384号 / 社医博第106号 / 新制||社||医11(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 妹尾 浩, 教授 古川 壽亮, 教授 中川 一路 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DFAM

Bacterial resistance is a formidable 21st-century global public health threat. If left unaddressed, we risk moving toward a “post-antibiotic era.” While resistance is a natural consequence of antibiotic use, the rate at which pathogenic bacteria have evaded multiple classes of drugs has markedly outpaced the introduction of new ones. New antibiotics are desperately needed to fill this void. Macrolides are one of the safest and most effective drug classes in medicine; however, resistance has compromised efficacy. To date, three generations have been developed with only the lattermost targeting bacterial resistance. Single next-generation macrolides will not keep pace with the inevitable onset of resistance; thus, there is a critical need to greatly accelerate the procurement of multiple future-generation antibiotics to tackle both current and future resistance mechanisms. My research is to meet this need by designing, synthesizing, and evaluating a novel, future-generation macrolide antibiotics that will serve as an armamentarium to be individually deployed on demand. In the previous research in Andrade group, we synthesized and evaluated various desmethyl ketolide analogs. The fact that 4-desmethyl telithromycin was fourfold less potent than telithromycin against A2058G mutants indicated replacing the 4-Me with hydrogen (i.e., desmethylation) to avoid a steric clash with the 2-amino group of G2058 was insufficient in rescuing bioactivity. Guided by MD simulation, we concluded a logical, superior alternative strategy was the replacement of the 4-Me group with one possessing a smaller vdW radius and capable of establishing favorable interactions with both wild-type and A2058G mutant ribosomes. Specifically, we reasoned that 4-fluoro solithromycin would be ideal candidate. The hypothesis was that the 4-fluoro moiety would engage in dipole-dipole interactions (C-F---H) with the exocyclic 2-amino group of guanine, which is based on accumulated evidence that strategic placement of organofluorine can strongly impact potency, selectivity, and physicochemical properties. In addition, the axially disposed of 4-fluorine would provide conformational stabilization from a gauche effect with the vicinal O5 group. The novel synthetic routes to unexplored desosamine analogs at the C3’-amino substituent to the macrolide antibiotic would play a role in bioactivity and resistance. Hofmann reaction was employed to execute the same 2,3-epoxide ring opening method without removing desosamine and re-glycosylating. This markedly reduces the steps, time, and cost involved in preparing novel desosamine-modified analogs. Significantly, this route enables the first synthesis of N,N’-disubstituted desosamine analogs from an epoxide, which was utilized to prepare novel analogs of clarithromycin. The application of in situ click chemistry toward the discovery of novel macrolide antibiotics first required the synthesis of suitable azide and aryl alkyne reactants. Alkyne partners were procured by commercial vendors or chemical synthesis. We targeted two logical, validated positions to tether the side chains, specifically N11 on the macrolactone and N3’ of desosamine. The first (N11) has been the most utilized. Moreover, extensive structure-activity relationships have revealed a four-carbon tether is ideal. Based on the solithromycin−E.coli X-ray structure, I designed, synthesized, and evaluated dehydro solithromycin, which possesses an (E)-alkene in the side-chain. The use of an unsaturated side chain would conformationally preorganize the bi-aryl side chain in order to pay the entropic penalty and thus favorably contribute to the overall binding. An insightful observation made from MD simulationed ribosomes bound with to solithromycin revealed that the interaction of the side-chain includes H-binding as well as π-stacking. The hypothesis was that employing tethered side-chains bearing motifs that maximize H-bonding and π-stacking would be superior antibiotics for treating resistant bacterial strains bearing erm¬-mediated N6 methyl and dimethylated ribosomes. To test this hypothesis, we developed various analogs with different alkynes by introducing different functional groups at the 3 and 5 positions on the aromatic ring. Another desosamine sugar modification is bis-azide. To date, the use of a two side chain strategy has not been reported. To access the requisite bis-azides, we employed a tactic the oxidative demethylation and alkylation of desosamine to afford bis-click solithromycin analogs. / Chemistry

Claritromicina era considerada um antibiótico de escolha para infecções causadas pelo complexo Mycobacterium abscessus, entretando, recentemente falhas no tratamento com este antibiótico têm sido reportadas. A resistência adquirida a claritromicina está relacionada à mutações pontuais que acarretam substituição da adenina na posição 2058 ou na posição 2059 na região do gene rrl que codifica o domínio peptidil transferase do rRNA 23S. Um mecanismo secundário de resistência à claritromicina tem sido descrito como resistência induzida, que é conferida pelo polimorfismo T/C no nucleotídeo 28 do gene erm(41). A resistência adquirida pode ser detectada em até 3 dias de incubação do M. abscessus com a claritromicina enquanto que a resistência induzida requer mais do que 5 dias de incubação. Por outro lado, o uso de marcadores moleculares para detecção de resistência adquirida e induzida no complexo M. abscessus têm sido propostos. O objetivo desse estudo foi avaliar o perfil de suscetibilidade e os marcadores moleculares de resistência à claritromicina no complexo M. abscessus. Um total de 42 isolados de um estudo prévio de vigilância, entre os anos 2007 e 2013 foram utilizados. O perfil de suscetibilidade para a claritromicina foi determinado por microdiluição em caldo com leituras em 3, 5, 7 e 14 dias. Mutações nos genes rrl e erm(41) foram avaliados por PCR com primers específicos e posterior sequenciamento. Resistência à claritromicina, em até 3 dias de incubação, foi observada em 31 dos 42 (73,8%) isolados. Resistência induzida à claritromicina foi observada em 6 de 11 (54,5%) isolados que apresentaram resistência após 5 ou 7 dias de incubação. Todos os isolados com resistência induzida foram M. abscessus subsp. massiliense. Além disso, todos os 28 isolados de M. abscessus subsp. massiliense apresentaram deleção em erm(41). Apenas cinco isolados foram sensíveis à claritromicina após 14 dias de incubação. Nenhum dos 42 isolados apresentaram mutação pontual na região de peptidil transferase do rRNA 23S e todos os isolados apresentaram o polimorfismo T/C no nucleotídeo 28 do gene erm(41). Os dados deste estudo indicam a falta de correlação dos marcadores moleculares com a expressão de resistência à claritromicina. / Infections due to Mycobacterium abscessus complex used to respond to clarithromycin treatment but more recently treatment failure with this antibiotic has been reported. Acquired resistance to clarithromycin is related to substitutions at the adenine either at position 2058 or at position 2059 in a region of the rrl gene encoding to the peptidyltransferase domain of the 23S rRNA. A secondary mechanism related to clarithromycin resistance has been described as an inducible resistance, conferred by T/C polymorphism at the 28th nucleotide in erm(41) gene. Acquired resistance can be detected up to 3 days of incubation of the M. abscessus with the clarithromycin while inducible resistance requires more than 5 days of incubation. Molecular markers to detect acquired and inducible resistance in M. abscessus complex isolates were proposed. This study evaluated the profile of susceptibility and the molecular markers of clarithromycin resistance in M. abscessus complex. A total of 42 isolates from a previous surveillance study (2007 to 2013) were used in this study. The susceptibility profile for clarithromycin was determined by broth microdilution with reads at 3, 5, 7 and 14 days. Mutations in rrl and erm(41) genes were evaluated by PCR with specific primers followed by sequencing. Clarithromycin resistance, up to 3 days of incubation, was observed in 31 of 42 (73.8%) isolates. Inducible clarithromycin resistance was observed in 6 of 11 (54.5%) isolates which presented resistance only after 5 or 7 days of incubation. All isolates with inducible resistance were identified as M. abscessus subsp. massiliense. Moreover, all 28 M. abscessus subsp. massiliense had a deletion in erm(41). Only five isolates proved to be susceptible to clarithromycin after 14 days of incubation. None of the 42 isolates presented a point mutation in the peptidyltransferase region of the 23S rRNA (rrl) and all isolates presented the T/C polymorphism at the 28th nucleotide of the erm(41) gene. The data of this study indicates a lack of correlation of molecular markers of clarithromycin resistance for both acquired and inducible resistance to clarithromycin.