Macrolide-lincosamide-streptogramin B resistance phenotypes and their associated genotypes in Staphylococcus aureus isolates from a tertiary level public hospital of Uruguay / Fenotipos de resistencia a macrólidos lincosamidas-estreptograminas B y sus genotipos asociados en Staphylococcus aureus aislados en un hospital público de nivel terciario en Uruguay

Abstract This study was undertaken to investígate the resistance phenotypes to macrolide-lincosamide-streptogramin B (MLSb) antibiotics and their associated genotypes in isolates of Staphylococcus aureus. We analyzed one hundred, consecutive, non-duplicate isolates (methicillin-susceptible MSSA, n = 53 and methicillin-resistant MRSA, n =47) obtained from var-ious clinical samples between July 2012 to December 2013. The resistance profile to MLSb antibiotics was determined by phenotypic methods and the resistance genes were detected by PCR assays. All of the isolates were subjected to pulsed-field gel electrophoresis (SmaI-PFGE). The overall prevalence of resistance to MLSb antibiotics was 38% and the resistance phenotype distribution was as follows: cMLSb, 22%; iMLSB, 10%; MSb, 5% and L, 1%. We detected ermA, ermC, ermB and mrsA/B genes in these resistant isolates. The single ermA gene was commonly observed mainly in those with a cMLSb R phenotype, whereas the combination ermA and ermC was more commonly observed in isolates with inducible expression. The patterns of SmaI-PFGE suggest a great genetic diversity in both MRSA and MSSA resistant to MLSb antibiotics. The results demonstrate the local presence of S. aureus resistant to MLSb antibiotics and its most frequently described responsible genes. Some of these isolates, especially those with the iMLSB phenotype, may be associated with therapeutic failure. Therefore, efforts should be directed to the correct detection of all MLSb resistant isolates using appropriate laboratory tests. PFGE results reveal a wide spread of resistance genes rather than the circulation of S. aureus clones resistant to MLSb antibiotics.

Resumen Los objetivos de este estudio fueron investigar en Staphylococcus aureus la presencia de fenotipos resistentes a los antibióticos macrólidos, lincosamidas y estreptograminas tipoB (MLSb) y conocer sus genotipos responsables. Analizamos 100 aislamientos consecutivos, no duplicados (53 sensibles a meticilina [MSSA] y 47 resistentes a meticilina [MRSA]), obtenidos entre 2012 y 2013 a partir de diferentes muestras clínicas. El perfil de resistencia a los antibióticos MLSb fue determinado por métodos fenotípicos y los genes de resistencia se detectaron por PCR. Todos los aislamientos fueron comparados por SmaI-PFGE. La prevalencia global de resistencia a los antibióticos MLSB fue del 38% y la distribución de los fenotipos de resistencia fue la siguiente: cMLSB, 22%; iMLSB, 10%; MSB, 5%; L, 1%. Se detectaron los genes ermA, ermC y mrsA/B en los aislamientos resistentes. El gen ermA se observó, sobre todo, en aislamientos con fenotipo resistente constitutivo R (cMLSB), mientras que la combinación ermA y ermC se detectó principalmente en aislamientos con resistencia inducible (iMLSB). Los patrones de Smal-PFGE sugieren una gran diversidad genética en los aislamientos resistentes a los antibióticos MLSb, tanto MRSA como MSSA. Los resultados demuestran la presencia local de S. aureus resistentes a los antibióticos MLSB y de sus genes responsables más frecuentemente descritos. Estos cultivos, especialmente aquellos con fenotipo resistente iMLSB, pueden asociarse con fallas terapéuticas. Por lo tanto, los esfuerzos deben dirigirse a la correcta detección de todos los cultivos resistentes a MLSB utilizando pruebas de laboratorio adecuadas. Los resultados de Smal-PFGE sugieren una amplia diseminación de genes de resistencia, más que la circulación de clones resistentes a los antibióticos MLSB.

Analysis of Resistance to Macrolide–Lincosamide–Streptogramin B Among mecA-Positive Staphylococcus Aureus Isolates

OBJECTIVES: Genetic determinants conferring resistance to macrolide, lincosamide, and streptogramin B (MLSB) via ribosomal modification such as, erm, msrA/B and ereA/B genes are distributed in bacteria. The main goals of this work were to evaluate the dissemination of MLSB resistance phenotypes and genotypes in methicillin-resistant Staphylococcus aureus (MRSA) isolates collected from clinical samples. METHODS: A total of 106 MRSA isolates were studied. Isolates were recovered from 3 hospitals in Tehran between May 2016 to July 2017. The prevalence of MLSB-resistant strains were determined by D-test, and then M-PCR was performed to identify genes encoding resistance to macrolides, lincosamides, and streptogramins in the tested isolates. RESULTS: The frequency of constitutive resistance MLSB, inducible resistance MLSB and MSB resistance were 56.2%, 22.9%, and 16.6%, respectively. Of 11 isolates with the inducible resistance MLSB phenotype, ermC, ermB, ermA and ereA were positive in 81.8%, 63.6%, 54.5% and 18.2% of these isolates, respectively. In isolates with the constitutive resistance MLSB phenotype, the prevalence of ermA, ermB, ermC, msrA, msrB, ereA and ereB were 25.9%, 18.5%, 44.4%, 0.0%, 0.0%, 11.1% and 0.0%, respectively. CONCLUSION: Clindamycin is commonly administered in severe MRSA infections depending upon the antimicrobial susceptibility findings. This study showed that the D-test should be used as an obligatory method in routine disk diffusion assay to detect inducible clindamycin resistance in MRSA so that effective antibiotic treatment can be provided.

Fenotipos de resistencia a meticilina, macrólidos y lincosamidas en Staphylococcus aureus aislados de un hospital de Valledupar, Colombia / Phenotype Resistance to Methicillin, Macrolides and Lincosamides in Staphylococcus Aureus, Isolated in a Hospital in Valledupar, Colombia / Fenótipos de resistência à meticilina, macrolídeos e lincosamidas em Staphylococcus aureus isolados de um hospital de Valledupar, Colombia

Introducción: las infecciones por S. aureus meticilino resistentes son un problema de salud pública por el perfil de multirresistencia que presenta este patógeno. Objetivo: determinar el fenotipo de resistencia a meticilina, macrólidos y lincosamidas en cepas de S. aureus. Materiales y métodos: se analizaron 50 cepas de S. aureus aisladas de muestras clínicas de pacientes del Hospital Rosario Pumarejo de López en la ciudad de Valledupar. Las pruebas de susceptibilidad a meticilina, eritromicina y clindamicina se realizaron por los métodos microdilución en caldo y difusión en agar. Se determinó la resistencia a meticilina mediante la técnica agar dilución y la resistencia inducible a clindamicina, con la prueba del D-Test. Resultados: la resistencia a meticilina fue del 50%, se evidenciaron cinco fenotipos en los macrólidos y lincosamidas analizados: el fenotipo con sensibilidad a eritromicina y clindamicina (78%), fenotipo con resistencia a eritromicina y clindamicina (16%), que presentan resistencia constitutiva para ambos antimicrobianos MLSBc, liderando los fenotipos de resistencia; el fenotipo con sensibilidad intermedia a ambos antimicrobianos (2%), el fenotipo con resultado intermedio para eritromicina y sensibilidad a clindamicina (2%) y el fenotipo con resistencia a eritromicina y sensibilidad a clindamicina (2%), que presentan resistencia inducible a clindamicina MLSBi, con prueba test D positiva. Conclusiones: la resistencia inducible para macrólidos, lincosamidas y streptograminas no se detecta usando los test de susceptibilidad antimicrobiana estándar. La no identificación de esta resistencia inducible puede conducir a falla del tratamiento con clindamicina.

Introduction: Infections with methicillin-resistant S. aureus are a public health problem due to the multi-resistance profile presented by this pathogen. Objective: To determine resistance phenotypes to methicillin, macrolides and lincosamides in S. aureus. Materials and methods: 50 S. aureus strains, isolated from patients of the Hospital Rosario Lopez Pumarejo in the city of Valledupar, were analyzed. Susceptibility tests to methicillin, erythromycin and clindamycin were performed using microdilution and agar diffusion methods. Methicillin resistance was determined through agar dilution technique and inducible clindamycin resistance D-Test. Results: Methicillin resistance reached 50%, five phenotypes were established in the analyzed macrolides and lincosamides: phenotype sensitive to erythromycin and clindamycin (78%); phenotype resistant to erythromycin and clindamycin (16%) with constitutive resistance for both cMLSB antimicrobials, which lead the resistance phenotypes; phenotype with intermediate resistance to both antimicrobials (2%); the intermediate result phenotype resistant to erythromycin and clindamycin (2%); and the RS phenotype resistant to erythromycin and sensitive to clindamycin (2%) that show inducible iMLSB clindamycin resistance with positive D test. Conclusions: The inducible resistance to macrolides, lincosamides and streptogramines is not established through the standard antimicrobial susceptibility test. Not identifying the inducible resistance can lead to clindamycin treatment failure.

Introdução: As infeções por S. aureus meticilino resistentes são um problema de saúde pública pelo perfil de multirresistência que apresenta este patógeno. Objetivo: Determinar o fenótipo de resistência à meticilina, macrolídeos e lincosamidad em cepas de S. aureus. Materiais e métodos: Analisaram-se 50 cepas de S. aureus isoladas de amostras clínicas de pacientes do Hospital Rosario Pumarejo de López na cidade de Valledupar, Colômbia. A susceptibilidade à meticilina, eritromicina e clindamicina se realizaram pelos métodos microdiluição em caldo e difusão em ágar. Determinou-se a resistência à meticilina mediante a técnica ágar diluição e a resistência induzível a clindamicina, com a prova D-Test. Resultados: A resistência a meticilina foi de 50%, se evidenciaram cinco fenótipos nos macrolídeos e lincosamidas analisados: o fenótipo com sensibilidade à eritromicina e clindamicina (78%), fenótipo com resistência à eritromicina e clindamicina (16%), que apresentam resistência constitutiva para ambos os antimicrobianos MLSBc, liderando os fenótipos de resistência; o fenótipo com sensibilidade intermedia a ambos os antimicrobianos (2%), o fenótipo com resultado intermédio para a eritromicina e sensibilidade à clindamicina (2%) e o fenótipo com resistência a eritromicina e sensibilidade à clindamicina (2%), que apresentam resistência induzível à clindamicina MLSBi, com prova test D positiva. Conclusões: A resistência induzível para macrolídeos, lincosamidas e streptograminas não se detecta usando os testes de susceptibilidade antimicrobiana standard. A não identificação desta resistência induzível pode conduzir à falha do tratamento com clindamicina.

Phenotypic and molecular characterization of resistance to macrolides, lincosamides and type B streptogramin of clinical isolates of Staphylococcus spp. of a university hospital in Recife, Pernambuco, Brazil

Abstract Introduction There is a mechanism of macrolide resistance in Staphylococcus spp. which also affects the lincosamides and type B streptogramins characterizing the so-called MLSB resistance, whose expression can be constitutive (cMLSB) or inducible (iMLSB) and is encoded mainly by ermA and ermC genes. The cMLSB resistance is easily detected by susceptibility testing used in the laboratory routine, but iMLSB resistance is not. Therapy with clindamycin in cases of infection with isolated iMLSB resistance may fail. Objective To characterize the phenotypic (occurrence of cMLSB and iMLSB phenotypes) and molecular (occurrence of ermA and ermC genes) profiles of MLSB resistance of clinical isolates of susceptible and methicillin-resistant Staphylococcus aureus and CNS (coagulase-negative Staphylococcus) from patients of a university hospital, in Pernambuco. Methods The antimicrobial susceptibility of 103 isolates was determined by the disk diffusion technique in Mueller–Hinton agar followed by oxacillin screening. The iMLSB phenotype was detected by D test. Isolates with cMLSB and iMLSB phenotypes were subjected to polymerase chain reaction (PCR) for the detection of ermA and ermC genes. Results The cMLSB and iMLSB phenotypes were respectively identified in 39 (37.9%) and five (4.9%) isolates. The iMLSB phenotype was found only in four (10.8%) methicillin-susceptible S. aureus and one (4.5%) methicillin-resistant S. aureus. In the 44 isolates subjected to PCR, four (9.1%) only ermA gene was detected, a lower frequency when compared to only ermC 17 (38.6%) gene and to one (2.3%) isolate presenting both genes. Conclusion In the Staphylococcus spp. analyzed, the ermC gene was found more often than the ermA, although the iMLSB phenotype had been less frequent than the cMLSB. It was important to perform the D test for its detection to guide therapeutic approaches.

The prevalence of genotypes that determine resistance to macrolides, lincosamides, and streptogramins B compared with spiramycin susceptibility among erythromycin-resistant Staphylococcus epidermidis

Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, can be regarded as potential reservoirs of resistance genes for pathogenic strains, e.g., Staphylococcus aureus. The aim of this study was to assess the prevalence of different resistance phenotypes to macrolide, lincosamide, and streptogramins B (MLSB) antibiotics among erythromycin-resistant S. epidermidis, together with the evaluation of genes promoting the following different types of MLSB resistance:ermA, ermB, ermC,msrA, mphC, and linA/A’. Susceptibility to spiramycin was also examined. Among 75 erythromycin-resistantS. epidermidis isolates, the most frequent phenotypes were macrolides and streptogramins B (MSB) and constitutive MLSB (cMLSB). Moreover, all strains with the cMLSB phenotype and the majority of inducible MLSB (iMLSB) isolates were resistant to spiramycin, whereas strains with the MSB phenotype were sensitive to this antibiotic. The D-shape zone of inhibition around the clindamycin disc near the spiramycin disc was found for some spiramycin-resistant strains with the iMLSB phenotype, suggesting an induction of resistance to clindamycin by this 16-membered macrolide. The most frequently isolated gene was ermC, irrespective of the MLSB resistance phenotype, whereas the most often noted gene combination wasermC, mphC, linA/A’. The results obtained showed that the genes responsible for different mechanisms of MLSB resistance in S. epidermidis generally coexist, often without the phenotypic expression of each of them.

Prevalence of resistance phenotypes in Staphylococcus aureus and coagulase-negative isolates of venous ulcers of primary healthcare patients / Prevalência de fenótipos de resistência em Staphylococcus aureus e coagulase negativos isolados de úlceras venosas de pessoas atendidas na atenção primária

INTRODUCTION: In venous ulcers, the presence of Staphylococcus aureus and coagulase-negative staphylococcus resistance phenotypes can aggravate and limit the choices for treatment. METHODS: Staphylococcus isolated from 69 patients (98 ulcers) between October of 2009 and October of 2010 were tested. The macrolide, lincosamide, streptogramin B (MLS B) group resistance phenotype detection was performed using the D-test. Isolates resistant to cefoxitin and/or oxacillin (disk-diffusion) were subjected to the confirmatory test to detect minimum inhibitory concentration (MIC), using oxacillin strips (E-test®). RESULTS: The prevalence of S. aureus was 83%, and 15% of coagulase-negative staphylococcus (CoNS). In addition were detected 28% of methicillin-resistant Staphylococcus aureus (MRSA) and 47% of methicillin-resistant coagulase-negative staphylococcus (MRCoNS). Among the S. aureus, 69.6% were resistant to erythromycin, 69.6% to clindamycin, 69.6% to gentamicin, and 100% to ciprofloxacin. Considering the MRSA, 74% were highly resistant to oxacillin, MIC ≥ 256µg/mL, and the MLS Bc constitutive resistance predominated in 65.2%. Among the 20 isolates sensitive to clindamycin, 12 presented an inducible MLS B phenotype. Of the MRCoNS, 71.4%were resistant to erythromycin, ciprofloxacin and gentamicin. Considering the isolates positive for β-lactamases, the MIC breakpoint was between 0.5 and 2µg/mL. CONCLUSIONS: The results point to a high occurrence of multi-drug resistant bacteria in venous ulcers in primary healthcare patients, thus evidencing the need for preventive measures to avoid outbreaks caused by multi-drug resistant pathogens, and the importance of healthcare professionals being able to identifying colonized versus infected venous ulcers as an essential criteria to implementing systemic antibacterial therapy.

INTRODUÇÃO: Em úlceras venosas, a presença de Staphylococcus aureus e coagulase negativo com fenótipos de resistência pode constituir fator agravante e limita as opções terapêuticas. MÉTODOS: Foram avaliados estafilococos isolados de 69 pacientes, representando 98 úlceras no período de outubro de 2009 a outubro de 2010. A detecção fenotípica da resistência ao grupo macrolide, lincosamide, streptogramin B (MLS B) foi realizada pelo D-test. Isolados resistentes a cefoxitina e/ou oxacilina (disco-difusão) foram submetidos ao teste confirmatório para detecção da minimum inhibitory concentration (MIC), empregando fitas de oxacilina (E-test®). RESULTADOS: A prevalência de S. aureus foi de 83% e de 15% de coagulase-negative staphylococcus (CoNS). Identificou-se 28% de methicillin-resistant Staphylococcus aureus (MRSA) e 47% de methicillin-resistant coagulase-negative staphylococcus (MRCoNS). Entre o S. aureus, 69,6% apresentaram resistência a eritromicina, 69,6% a clindamicina, 69,6% a gentamicina e 100% a ciprofloxacina. Setenta e quatro por cento dos MRSA apresentaram elevado nível de resistência a oxacilina, MIC ≥ 256µg/mL, e em 65,2% predominou a resistência constitutiva MLS Bc. Dos 20 isolados sensíveis a clindamicina, 12 apresentaram fenótipo MLS B induzível. Um total de 71,4% dos MRCoNS apresentaram resistência a eritromicina, ciprofloxacina e gentamicina. Dos isolados positivos para a enzima β-lactamases, as MIC tiveram breakpoint entre 0,5 a 2µg/mL. CONCLUSÕES: Os resultados sinalizam elevada ocorrência de bactérias multirresistentes em úlceras venosas de pacientes recebendo atenção primária, evidenciando a necessidade de medidas preventivas que evitem surtos causados por patógenos resistentes a múltiplas drogas e a importância dos profissionais em discernir infecção de colonização em úlcera venosa, critério fundamental na indicação antibioticoterapia sistêmica.

Determinación de staphylococcus aureus meticilino resistente de la comunidad (Sarm-com) en dos hospitales de Guatemala / Determination of methicillin resistant staphylococcus aureus community (Sarm-com) in two hospitals in Guatemala

El objetivo de este trabajo fue determinar cepas de Stapylococcus aureus meticilino resistente de la comunidad (SARM-com) en aislamientos provenientes de infecciones de la piel de pacientes del Hospital Roosevelt y hospital nacional Pedro de Betancourt de Guatemala. Para ello se realizó un estudio exploratorio de tipo descriptivo el cual consistió en un muestreo de 12 semanas en el laboratorio de microbiología del hospital Roosevelt y del hospital nacional Pedro de Betancourt. Se recolectaron las cepas que cumplieron con los siguientes criterios: haber sido identificadas como S. aureus, que presentaran resistencia a todos los betalactámicos, por medio de la resistencia a oxacilina y como resistencia variable a macrólidos y lincosamidas...

The Trend of Antibiotic Production in Korea during 1981~2003 / 감염과화학요법

BACKGROUND: It is difficult to know the actual situation of antibiotic usage in Korea. We investigated the trend of antibiotic production every five years from 1981 to 2003 by using two parameters:the cost and the amount of antibiotics produced in Korea. MATERIALS AND METHODS: We analysed the data from "Annual Products of Medicine" published by Korea Pharmaceutical Manufactures Association. All antibiotics were classified into generic names, and the cost and the amount of antibiotic produced were compared with the results from previous years. RESULTS: The total production cost and the amount of antibiotics increased since 1980 and by 2003, it was 1,306 billion won and 965 tons respectively. However, the increasing rate of production cost has slowed down since 2000. Among all antibiotics produced in Korea, cephalosporins recorded the highest production cost, reaching 595 billion won (45.6%) in 2003. Cephalosporins made the largest portion of the total amount:252 tons (26.2%). Both 3rd and 4th generation cephlosporins have increased gradually. The second most frequently produced antibiotics in terms of amount were penicillins, although it decreased by 25% since 1998. Aminoglycosides showed similar production cost, but the production amount decreased compared to that of 1998. The production amount of quinolones had skyrocketed to 641% from 1998. Tetracyclines, lincosamides, and chloramphenicols insignificantly decreased in both production cost and amount. CONCLUSION: There seems to be an increase of antibiotics in production cost and amount in Korea, but the overall increasing rate of the cost has slowed down since 2000. The newer and more expensive antibiotics have grown in production.

The Trend of Antibiotic Production in Korea during 1981~2003 / 감염과화학요법

BACKGROUND: It is difficult to know the actual situation of antibiotic usage in Korea. We investigated the trend of antibiotic production every five years from 1981 to 2003 by using two parameters:the cost and the amount of antibiotics produced in Korea. MATERIALS AND METHODS: We analysed the data from "Annual Products of Medicine" published by Korea Pharmaceutical Manufactures Association. All antibiotics were classified into generic names, and the cost and the amount of antibiotic produced were compared with the results from previous years. RESULTS: The total production cost and the amount of antibiotics increased since 1980 and by 2003, it was 1,306 billion won and 965 tons respectively. However, the increasing rate of production cost has slowed down since 2000. Among all antibiotics produced in Korea, cephalosporins recorded the highest production cost, reaching 595 billion won (45.6%) in 2003. Cephalosporins made the largest portion of the total amount:252 tons (26.2%). Both 3rd and 4th generation cephlosporins have increased gradually. The second most frequently produced antibiotics in terms of amount were penicillins, although it decreased by 25% since 1998. Aminoglycosides showed similar production cost, but the production amount decreased compared to that of 1998. The production amount of quinolones had skyrocketed to 641% from 1998. Tetracyclines, lincosamides, and chloramphenicols insignificantly decreased in both production cost and amount. CONCLUSION: There seems to be an increase of antibiotics in production cost and amount in Korea, but the overall increasing rate of the cost has slowed down since 2000. The newer and more expensive antibiotics have grown in production.

The Trend of Antibiotics Usage in Korea during 1981-1998 / 감염

BACKGROUND: With the time course, the cost and the amounts of produced antibiotics are increasing but it is difficult to get the exact data and there were limitations to know the trend of antibiotics usage. So we examined the trend of antibiotics usage every five year during 1981-1998 by using two parameters; the cost and the amount of antibiotics produced in South Korea. METHODS: We used the data from 'Annual products of medicine' published by Korea Pharmaceutical Manufactures Association. Every antibiotics were classified to generic names, and the cost and the amounts of produced antibiotics were compared each year. RESULTS: In 1998, the total cost of produced antibiotics was 1,150 billion won and the amount was 708.6 ton. The cost was increased by 20.0% compared to that of 1995. Cephalosporins made the largest proportion of the cost in antibiotic production that was 43.8% (503.3 billion won) in 1998. With the time course proportion of the third and the second generation cephalosporins were increased. Penicillins made the largest proportion (46%) of the total amount and were produced 325.7 ton. Among them, aminopenicillins were 86% of the total cost of penicillins and 95% of the total amount of penicillins. Especially the cost of aminopenicillins with beta-lactamase inhibitor was 2.3 times increased since 1993 thus made the major cause of increase. Quinolones were increased 2.1 times and macrolides were increased 2.2 times in production cost for 5 years. Tetracyclines, lincosamides and chloramphenicols were decreased in both production cost and amount, but penicillins and macrolides were increased in production cost even though production amounts were decreased. CONCLUSION: There seemed to be an increase in the cost and the amount of antibiotic production in Korea. Especially productions of newer drugs such as aminopenicillins with beta-lactamase inhibitor, third generation cephalosporins, some of macrolides and carbapenems were increased remarkably. And the use of glycopetides, anti-fungal agents, and antiviral agents were increasing also. Some drugs were thought to be an inappropriate use. More epidemiologic study and the guidelines for the proper use of antibiotics are needed.