The mazEF toxin-antitoxin system as a novel antibacterial target in Acinetobacter baumannii

Although analysis of toxin-antitoxin (TA) systems can be instructive, to date, there is no information on the prevalence and identity of TA systems based on a large panel of Acinetobacter baumannii clinical isolates. The aim of the current study was to screen for functional TA systems among clinical isolates of A. baumannii and to identify the systems’ locations. For this purpose, we screened 85 A. baumannii isolates collected from different clinical sources for the presence of the mazEF, relBE and higBA TA genes. The results revealed that the genes coding for the mazEF TA system were commonly present in all clinical isolates of A. baumannii. Reverse transcriptase-polymerase chain reaction analysis showed that transcripts were produced in the clinical isolates. Our findings showed that TA genes are prevalent, harboured by chromosomes and transcribed within A. baumannii. Hence, activation of the toxin proteins in the mazEF TA system should be investigated further as an effective antibacterial strategy against this bacterium.

Isolation and Identification of Methicillin- Resistant Staphylococcus aureus from Keys of College Students Using Different Detection Methods.

Aims: In this study, the methicillin-resistant Staphylococcus aureus (MRSA) were isolated and identified by using biochemical tests, antibiogram and polymerase chain reaction (PCR) to explore the circulation of MRSA among college students. Study design: Cross-sectional study. Place and Duration of Study: Department of Medical Microbiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia between June 2010 and December 2010. Methodology: A total of 100 samples were collected from keys of college students. There were 39 isolates (39 %) Gram-positive cocci and Catalase positive. 29 (74.36%) were glucose oxidation and fermentation positive. From the 39 isolates, 16 (43.24%) were shown Mannitol Salt Agar (MSA) tests positive. The deoxyribonuclease (DNase) tests and tube coagulase tests with human and rabbit plasma were carried out to improve the efficiency of the MSA test. Results: 7 (43.75%) DNase positive and 2 (12.5%) tube coagulase positive. Both human and rabbit plasma showed similar sensitivity for the tube coagulase tests in this study. However, both isolates with tube coagulase positive were confirmed as S. aureus but not resistant to oxacillin, methicillin, erythromycin and cefoxitin. 2 (66.67%) of 3 (18.75%) isolates which is tube coagulase negative were resistant to erythromycin and 1 (33.33%) of them was resistant to methicillin. Rare strains of S. aureus can be coagulase negative. PCR assay was used. 1 (33.33%) of the coagulase negative isolate resistant to erythromycin was found to have nuc gene, mecA gene, ermC gene, msrA gene, linA gene, and femA gene. The isolate was confirmed as MRSA. Conclusion: In conclusion, PCR technique is more sensitive and reliable than tube coagulase test or antibiogram for the detection of MRSA. And keys were shown to be an important source of MRSA and other bacteria circulation in the community.

Incidence of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae in patients with urinary tract infection / Incidência de Klebsiella pneumoniae produtoras de beta-lactamases de espectro estendido em pacientes com infecção do trato urinário

CONTEXT AND OBJECTIVES: Resistant bacteria are emerging worldwide as a threat to favorable outcomes from treating common infections in community and hospital settings. The present investigation was carried out to study the incidence of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in patients with urinary tract infection in different seasons of the year, in order to determine the prevalence of the genes blaTEM, blaSHV and blaCTX-M, which are responsible for ESBL production among ESBL-producing K. pneumoniae, in three cities in Iran, and to investigate the antimicrobial susceptibility pattern of K. pneumoniae in different seasons. DESIGN AND SETTING: Retrospective study carried out among patients with urinary tract infections in five hospitals in Iran. METHOD: Two hundred and eighty-eight clinical isolates of K. pneumoniae were collected between March 2007 and April 2008 from five hospitals in three cities in Iran. ESBLs were identified by phenotypic and genotypic methods. ESBL-producing Klebsiella pneumoniae were evaluated against non-beta-lactam antibiotics. Genes coding for ESBLs (blaSHV, TEM and CTX-M) were screened. RESULTS: Among the 288 clinical isolates of K. pneumoniae, 37.7 percent, 46.7 percent and 15.6 percent were obtained from hospitals in Ilam, Tehran and Tabriz, respectively, of which 39.4 percent, 50.7 percent and 45.8 percent were ESBL-producing K. pneumoniae in Ilam, Milad and Emam Reza hospitals, respectively. CONCLUSION: According to the results from this study, resistance to third-generation cephalosporins is higher during the cold months than during the warm months.

CONTEXTO E OBJETIVOS: As bactérias resistentes estão surgindo em todo o mundo como uma ameaça ao resultado favorável no tratamento de infecções comuns em ambientes comunitários e hospitalares. O presente estudo foi realizado com o objetivo de avaliar a incidência de Klebsiella pneumoniae produtoras de beta-lactamases de espectro estendido (BLEEs) em pacientes com infecção do trato urinário em diferentes estações do ano, para verificar a prevalência dos genes blaTEM, blaSHV e blaCTX-M responsáveis para a produção de BLEEs em K. pneumoniae productoras de BLEEs, em três cidades do Irã, e investigar o perfil de sensibilidade antimicrobiana de K. pneumoniae em diferentes estações. DESENHO E LOCAL: Estudo retrospectivo realizado em pacientes com infecções do trato urinário em cinco hospitais no Irã. MÉTODO: Duzentos e oitenta e oito isolados clínicos de K. penumoniae foram coletados entre março de 2007 e abril de 2008 em cinco hospitais de três cidades no Irã. BLEEs foram identificados por métodos fenotípicos e genotípicos. K. pneumoniae produtoras de BLEEs foram avaliadas contra antibióticos não beta-lactâmicos. Os genes codificadores de BLEEs (blaSHV, TEM e CTX-M) foram investigados. RESULTADOS: Entre os 288 isolados clínicos de K. pneumoniae, 37,7 por cento, 46,7 por cento e 15,6 por cento eram provenientes dos hospitais em Ilam, Tehran e Tabriz, respectivamente, dos quais 39,4 por cento, 50,7 por cento e 45,8 por cento eram K. pneumoniae produtoras de BLEEs nos hospitais em Ilam, Milad e Eman Reza, respectivamente. CONCLUSÃO: De acordo com os resultados deste estudo, a resistência às cefalosporinas de terceira geração é maior nos meses frios do que nos meses quentes.