Evaluation of in-vitro susceptibility of ß-lactam-resistant Gram-negative bacilli to ceftazidime-avibactam and ceftolozane-tazobactam from clinical samples of a general hospital in southern Brazil

ABSTRACT Background: The spread of carbapenemase- and extended-spectrum β-lactamase (ESBL)-producing gram-negative bacilli (GNB) represent a global public health threat that limits therapeutic options for hospitalized patients. This study aimed to evaluate the in-vitro susceptibility of β-lactam-resistant GNB to ceftazidime-avibactam (C/A) and ceftolozane-tazobactam (C/T), and investigate the molecular determinants of resistance. Methods: Overall, 101 clinical isolates of Enterobacterales and Pseudomonas aeruginosa collected from a general hospital in Brazil were analyzed. Susceptibility to the antimicrobial agents was evaluated using an automated method, and the minimum inhibitory concentrations (MIC50/90) of C/A and C/T were determined using Etest®. The β-lactamase-encoding genes were investigated using polymerase chain reaction. Results: High susceptibility to C/A and C/T was observed among ESBL-producing Enterobacterales (100% and 97.3% for CLSI and 83.8% for BRCAST, respectively) and carbapenem-resistant P. aeruginosa (92.3% and 87.2%, respectively). Carbapenemase-producing Klebsiella pneumoniae exhibited high resistance to C/T (80%- CLSI or 100%- BRCAST) but high susceptibility to C/A (93.4%). All carbapenem-resistant K. pneumoniae isolates were susceptible to C/A, whereas only one isolate was susceptible to C/T. Both antimicrobials were inactive against metallo-β-lactamase-producing K. pneumoniae isolates. Resistance genes were concomitantly identified in 44 (44.9%) isolates, with bla CTX-M and bla SHV being the most common. Conclusions: C/A and C/T were active against microorganisms with β-lactam-resistant phenotypes, except when resistance was mediated by metallo-β-lactamases. Most C/A- and C/T-resistant isolates concomitantly carried two or more β-lactamase-encoding genes (62.5% and 77.4%, respectively).

Perfil fenotípico de resistência à colistina e tigeciclina em um hospital público no Brasil / Phenotypical profile of colistin and tigecycline resistance in a public hospital in Brazil / Perfil fenotípico de resistencia a la colistina y tigeciclina en un hospital público de Brasil

Justificativa e objetivos: Infecções Relacionadas à Assistência à Saúde (IRAS) causadas por bacilos Gram negativos multirresistentes (BGN-MDR) são consideradas um problema de saúde pública e um impacto nas taxas de mortalidade nas Unidades de Terapia Intensiva (UTI). O objetivo deste estudo foi verificar o perfil fenotípico de resistência à colistina e à tigeciclina, consideradas como último recurso terapêutico aos BGN-MDR. Métodos: Os dados foram coletados nas fichas de busca ativa do serviço de controle de infecções e prontuários médicos de pacientes internados em duas UTIs de um hospital público de Joinville, entre janeiro de 2016 e junho de 2017. Resultados: Ocorreram 256 IRAS por BGN, acometendo principalmente o gênero masculino (62%), com mediana de idade de 65 anos. Entre os BGN, 37% expressaram MDR; sendo as espécies mais frequentes: Klebsiella pneumoniae e (47%), Acinetobacter baumannii (23%) e Stenotrophomonas maltophilia (11%). A resistência de BGN-MDR à colistina e tigeciclina foi de 5% e de 12%, respectivamente; 5% dos isolados foram resistentes aos dois antibióticos. A taxa de óbito entre os pacientes com IRAS por BGN-MDR resistentes à colistina foi mais alta (60%) que aquelas à tigeciclina (45%). Conclusão: K. pneumoniae e A. baumannii produtores de carbapenemases, resistentes a colistina e tigeciclina prevaleceram entre os BGN-MDR, e estiveram associadas a maioria dos óbitos. Essas observações, junto com o alto uso de carbapenêmicos na terapia empírica, mostra a necessidade do uso racional de antimicrobianos.(AU)

Background and objectives: Healthcare-associated Infections (HAIs) caused by multidrug-resistant Gram-negative bacilli (GNB-MDR) are considered a public health problem and have an impact on mortality rates in Intensive Care Units (ICU). The aim of this study was to verify the phenotypic profile of resistance to colistin and tigecycline, considered as the last antimicrobial choice to treat BGNMDR infections. Methods: Data were collected on the active search records of the infection control service and medical records of patients admitted to two ICUs at a public hospital in Joinville between January 2016 and June 2017. Results: There were 256 HAIs caused by GNB, mainly affecting males (62%), with a median age of 65 years. Among GNBs, 37% expressed MDR; the most frequent species were: Klebsiella pneumoniae (47%), Acinetobacter baumannii (23%) and Stenotrophomonas maltophilia (11%). The resistance of GNB-MDR to colistin and tigecycline was 5% and 12%, respectively; 5% of the isolates were resistant to both antibiotics. The death rate among patients with HAIs caused by colistin-resistant GNB-MDR was higher (60%) than those to tigecycline (45%). Conclusion: Carbapenemase-producing K. pneumoniae and A. baumannii, resistant to colistin and tigecycline, prevailed among GNB-MDRs, and were associated with most deaths. These observations, coupled with the high use of carbapenems in empirical therapy, show the need for rational use of antimicrobials.(AU)

Justificación y objetivos: Las Infección nosocomial (IHs) causadas por bacilos Gram negativos multirresistentes (BGN-MDR) se consideran un problema de salud pública y un impacto en las tasas de mortalidad en las Unidades de Terapia Intensiva (UTI). El objetivo de este estudio fue verificar el perfil fenotípico de resistencia a la colistina ya la tigeciclina, consideradas como último recurso terapéutico a los BGN-MDR. Métodos: Los datos fueron recolectados en las fichas de búsqueda activa del servicio de control de infecciones y prontuarios médicos de pacientes internados en dos UTIs de un hospital público de Joinville, entre enero de 2016 y junio de 2017. Resultados: Ocurrieron 256 IHs por BGN, que afectan principalmente al género masculino (62%), con mediana de edad de 65 años. Entre los BGN, el 37% expresó MDR; siendo las especies más frecuentes: Klebsiella pneumoniae (47%), Acinetobacter baumannii (23%) y Stenotrophomonas maltophilia (11%). La resistencia de BGN-MDR a la colistina y tigeciclina fue del 5% y del 12%, respectivamente; 5% de los aislados fueron resistentes a los dos antibióticos. La tasa de muerte entre los pacientes con IH causadas por los BGN-MDR resistentes la colistina fue más alta (60%) que aquellas a tigeciclina (45%). Conclusión: K. pneumoniae y A. baumannii productoras de carbapenemases, resistentes la colistina y la tigeciclina, fueron más frecuentes entre los BGN-MDR y su asociación estuvo presente en la mayoría de las muertes. Estas observaciones, junto con el alto uso de carbapenems en la terapia empírica, muestran la necesidad de un uso racional de los antimicrobianos.(AU)

Earliest identification of New Delhi metallo-ß-lactamase 1 (NDM-1) in Acinetobacter pittii in Brazil

Abstract We report the occurrence in Brazil of the bla NDM-1 gene in Acinetobacter pittii, prior to the previously described first reports regarding the species Providencia rettgeri and Enterobacter hormaechei. Clinical isolates were investigated by polymerase chain reaction followed by bidirectional sequencing, and species was confirmed by 16S rDNA sequencing and matrix-assisted laser desorption-ionization time-of-flight spectrometry. A. pittii carrying bla NDM-1 was confirmed in a patient with no national or international travel history, or transfer from another hospital. The findings warn of the possibility of silent spread of bla NDM-1 to the community.

The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting

Abstract: INTRODUCTION: Members of the Acinetobacter genus are key pathogens that cause healthcare-associated infections, and they tend to spread and develop new antibiotic resistance mechanisms. Oxacillinases are primarily responsible for resistance to carbapenem antibiotics. Higher rates of carbapenem hydrolysis might be ascribed to insertion sequences, such as the ISAba1 sequence, near bla OXA genes. The present study examined the occurrence of the genetic elements bla OXA and ISAba1 and their relationship with susceptibility to carbapenems in clinical isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. METHODS: Isolates identified over 6 consecutive years in a general hospital in Joinville, Southern Brazil, were evaluated. The investigation of 5 families of genes encoding oxacillinases and the ISAba1 sequence location relative to bla OXA genes was conducted using polymerase chain reaction. RESULTS: All isolates presented the bla OXA-51-like gene (n = 78), and 91% tested positive for the bla OXA-23-like gene (n = 71). The presence of ISAba1 was exclusively detected in isolates carrying the bla OXA-23-like gene. All isolates in which ISAba1 was found upstream of the bla OXA-23-like gene (n = 69) showed resistance to carbapenems, whereas the only isolate in which ISAba1 was not located near the bla OXA-23-like gene was susceptible to carbapenems. The ISAba1 sequence position of another bla OXA-23-like-positive isolate was inconclusive. The isolates exclusively carrying the bla OXA-51-like gene (n = 7) showed susceptibility to carbapenems. CONCLUSIONS: The presence of the ISAba1 sequence upstream of the bla OXA-23-like gene was strongly associated with carbapenem resistance in isolates of the A. calcoaceticus-A. baumannii complex in the hospital center studied.

Antimicrobial resistance profiles and oxacillinase genes in carbapenem-resistant Acinetobacter baumannii isolated from hospitalized patients in Santa Catarina, Brazil

Abstract: INTRODUCTION: Carbapenems are the therapy of choice for treating severe infections caused by the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. We aimed to assess the prevalence and antimicrobial susceptibility profiles of producers of distinct oxacillinases among nosocomial isolates of the A. calcoaceticus-A. baumannii complex in a 249-bed general hospital located in Joinville, Southern Brazil. METHODS: Of the 139 A. baumannii clinical isolates with reduced susceptibility to carbapenems between 2010 and 2013, 118 isolates from varying anatomical sites and hospital sectors were selected for genotypic analysis. Five families of genes encoding oxacillinases, namely blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like, and blaOXA-143-like, wereinvestigated by multiplex polymerase chain reaction (PCR). RESULTS: Most (87.3%) isolates simultaneously carried the blaOXA-23-likeand blaOXA-51-likegenes, whereas three (2.5%) isolates harbored only blaOXA-51-likeones. The circulation of carbapenem-resistant isolates increased during the study period: from none in 2010, to 22 in 2011, 64 in 2012, and 53 in 2013. CONCLUSIONS: Isolates carrying the blaOXA-23-likeand blaOXA-51-likegenes were widely distributed in the hospital investigated. Because of the worsening scenario, the implementation of preventive measures and effective barriers is needed.