scholarly journals Comparison of Tn1546-Like Elements in Vancomycin-Resistant Staphylococcus aureus Isolates from Michigan and Pennsylvania

2005 ◽  
Vol 49 (1) ◽  
pp. 470-472 ◽  
Author(s):  
Nancye C. Clark ◽  
Linda M. Weigel ◽  
Jean B. Patel ◽  
Fred C. Tenover
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Analysis ◽  
Dna Sequence ◽  
Intergenic Region ◽  
Mobile Genetic Element ◽  
Clinical Isolates ◽  
Genetic Element ◽  
Vancomycin Resistant ◽  
High Level ◽  
Genetic Events

ABSTRACT In 2002, the first two clinical isolates of vancomycin-resistant Staphylococcus aureus (VRSA) containing vanA were recovered in Michigan and Pennsylvania. Tn1546, a mobile genetic element that encodes high-level vancomycin resistance in enterococci, was present in both isolates. With PCR and DNA sequence analysis, we compared the Tn1546 elements from each isolate to the prototype Tn1546 element. The Michigan VRSA element was identical to the prototype Tn1546 element. The Pennsylvania VRSA element showed three distinct modifications: a deletion of nucleotides 1 to 3098 at the 5′ end, which eliminated the orf1 region; an 809-bp IS1216V-like element inserted before nucleotide 3099 of Tn1546; and an inverted 1,499-bp IS1251-like element inserted into the vanSH intergenic region. These differences in the Tn1546-like elements indicate that the first two VRSA isolates were the result of independent genetic events.

scholarly journals Mobile-Genetic-Element-Encoded Hypertolerance to Copper ProtectsStaphylococcus aureusfrom Killing by Host Phagocytes

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Marta Zapotoczna ◽  
Gustavo P. Riboldi ◽  
Ahmed M. Moustafa ◽  
Elizabeth Dickson ◽  
Apurva Narechania ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Human Blood ◽  
Immune Cells ◽  
Mobile Genetic Element ◽  
Mobile Genetic Elements ◽  
Clinical Isolates ◽  
Genetic Element ◽  
Methicillin Resistant ◽  
Content Type ◽  
Phagocytic Killing

ABSTRACTPathogens are exposed to toxic levels of copper during infection, and copper tolerance may be a general virulence mechanism used by bacteria to resist host defenses. In support of this, inactivation of copper exporter genes has been found to reduce the virulence of bacterial pathogensin vivo. Here we investigate the role of copper hypertolerance in methicillin-resistantStaphylococcus aureus(MRSA). We show that a copper hypertolerance operon (copB-mco), carried on a mobile genetic element (MGE), is prevalent in a collection of invasiveS. aureusstrains and more widely among clonal complex 22, 30, and 398 strains. ThecopBandmcogenes encode a copper efflux pump and a multicopper oxidase, respectively. Isogenic mutants lackingcopBormcohad impaired growth in subinhibitory concentrations of copper. Transfer of acopB-mco-carrying plasmid to a naive clinical isolate resulted in a gain of copper hypertolerance and enhanced bacterial survival inside primed macrophages. ThecopBandmcogenes were upregulated within infected macrophages, and their expression was dependent on the copper-sensitive operon repressor CsoR. IsogeniccopBandmcomutants were impaired in their ability to persist intracellularly in macrophages and were less resistant to phagocytic killing in human blood than the parent strain. The importance of copper-regulated genes in resistance to phagocytic killing was further elaborated using mutants expressing a copper-insensitive variant of CsoR. Our findings suggest that the gain of mobile genetic elements carrying copper hypertolerance genes contributes to the evolution of virulent strains ofS. aureusthat are better equipped to resist killing by host immune cells.IMPORTANCEMethicillin-resistantStaphylococcus aureus(MRSA) poses a substantial threat to human health worldwide and evolves rapidly by acquiring mobile genetic elements, such as plasmids. Here we investigate how thecopB-mcocopper hypertolerance operon carried on a mobile genetic element contributes to the virulence potential of clinical isolates of MRSA. Copper is a key component of innate immune bactericidal defenses. Here we show that copper hypertolerance genes enhance the survival ofS. aureusinside primed macrophages and in whole human blood. ThecopBandmcogenes are carried by clinical isolates responsible for invasive infections across Europe, and more broadly among three successful clonal lineages ofS. aureus. Our findings show that a gain of copper hypertolerance genes increases the resistance of MRSA to phagocytic killing by host immune cells and imply that acquisition of this mobile genetic element can contribute to the success of MRSA.

scholarly journals Staphylococcus aureus Mutants Isolated via Exposure to Nonfluorinated Quinolones: Detection of Known and Unique Mutations

2001 ◽  
Vol 45 (12) ◽  
pp. 3422-3426 ◽  
Author(s):  
Siddhartha Roychoudhury ◽  
Tracy L. Twinem ◽  
Kelly M. Makin ◽  
Mark A. Nienaber ◽  
Chuiying Li ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Sequence Analysis ◽  
Efflux Pump ◽  
Serial Passage ◽  
Efflux Pump Inhibitor ◽  
In Vitro Development ◽  
Development Of Resistance ◽  
High Level ◽  
Vitro Development

ABSTRACT The in vitro development of resistance to the new nonfluorinated quinolones (NFQs; PGE 9262932, PGE 4175997, and PGE 9509924) was investigated in Staphylococcus aureus. At concentrations two times the MIC, step 1 mutants were isolated more frequently with ciprofloxacin and trovafloxacin (9.1 × 10−8 and 5.7 × 10−9, respectively) than with the NFQs, gatifloxacin, or clinafloxacin (<5.7 × 10−10). Step 2 and step 3 mutants were selected via exposure of a step 1 mutant (selected with trovafloxacin) to four times the MICs of trovafloxacin and PGE 9262932. The step 1 mutant contained the known Ser80-Phe mutation in GrlA, and the step 2 and step 3 mutants contained the known Ser80-Phe and Ser84-Leu mutations in GrlA and GyrA, respectively. Compared to ciprofloxacin, the NFQs were 8-fold more potent against the parent and 16- to 128-fold more potent against the step 3 mutants. Mutants with high-level NFQ resistance (MIC, 32 μg/ml) were isolated by the spiral plater-based serial passage technique. DNA sequence analysis of three such mutants revealed the following mutations: (i) Ser84-Leu in GyrA and Glu84-Lys and His103-Tyr in GrlA; (ii) Ser-84Leu in GyrA, Ser52-Arg in GrlA, and Glu472-Val in GrlB; and (iii) Ser84-Leu in GyrA, Glu477-Val in GyrB, and Glu84-Lys and His103-Tyr in GrlA. Addition of the efflux pump inhibitor reserpine (10 μg/ml) resulted in 4- to 16-fold increases in the potencies of the NFQs against these mutants, whereas it resulted in 2-fold increases in the potencies of the NFQs against the parent.

scholarly journals Staphylococcus aureus Infections in Malaysia: A Review of Antimicrobial Resistance and Characteristics of the Clinical Isolates, 1990–2017

Antibiotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 128 ◽  
Author(s):  
Ainal Mardziah Che Hamzah ◽  
Chew Chieng Yeo ◽  
Suat Moi Puah ◽  
Kek Heng Chua ◽  
Ching Hoong Chew
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Resistance ◽  
Sccmec Type ◽  
Epidemiological Data ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Type Iv ◽  
Resistant Strains ◽  
Vancomycin Resistant ◽  
Comprehensive Surveillance

Staphylococcus aureus is an important nosocomial pathogen and its multidrug resistant strains, particularly methicillin-resistant S. aureus (MRSA), poses a serious threat to public health due to its limited therapeutic options. The increasing MRSA resistance towards vancomycin, which is the current drug of last resort, gives a great challenge to the treatment and management of MRSA infections. While vancomycin resistance among Malaysian MRSA isolates has yet to be documented, a case of vancomycin resistant S. aureus has been reported in our neighboring country, Indonesia. In this review, we present the antimicrobial resistance profiles of S. aureus clinical isolates in Malaysia with data obtained from the Malaysian National Surveillance on Antimicrobial Resistance (NSAR) reports as well as various peer-reviewed published records spanning a period of nearly three decades (1990–2017). We also review the clonal types and characteristics of Malaysian S. aureus isolates, where hospital-associated (HA) MRSA isolates tend to carry staphylococcal cassette chromosome mec (SCCmec) type III and were of sequence type (ST)239, whereas community-associated (CA) isolates are mostly SCCmec type IV/V and ST30. More comprehensive surveillance data that include molecular epidemiological data would enable further in-depth understanding of Malaysian S. aureus isolates.

scholarly journals Vancomycin Sensitivity of Clinical Isolates of Staphylococcus aureus from Patients in Dhaka City, Bangladesh

2012 ◽  
Vol 15 (2) ◽  
pp. 159-163 ◽  
Author(s):  
Mohammad Shahriar ◽  
Sanjida Shahid ◽  
Khusbu Khalil Katha ◽  
Waheeda Nasreen ◽  
Mohiuddin Ahmed Bhuiyan
Keyword(s):  
Staphylococcus Aureus ◽  
Pharmaceutical Journal ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Multiple Drug ◽  
Beta Lactamase ◽  
Antimicrobial Drugs ◽  
Multiple Drug Resistant ◽  
Vancomycin Resistant ◽  
Drug Resistant Strains

Methicillin-resistant Staphylococcus aureus (MRSA), resistant to all antibiotics including vancomycin, has been reported in Japan, USA, Canada and Brazil. Hence, the main objective of this study was to evaluate the possible presence of vancomycin resistant or intermediate Stap. aureus in Dhaka. A total of 122 clinical isolates were collected from different hospitals, clinics and diagnostic centers of the city for about 12 months starting from August 2010 to July 2011.They were identified using standard bacteriological methods. Sensitivity to recommended antibiotics was determined by disc diffusion method. In the present study 74% of total isolates were found to be betalactamase producers by iodometric methods, whereas with Nitrocefin® sticks 80% of the isolates were found to be beta-lactamase producers. All the multiple drug resistant strains were beta-lactamase producers. Out of 122 isolates, although no strains were found vancomycin resistant, 93.44% were found intermediate and only 6.56% showed sensitivity. This study reveals the growing antimicrobial resistance in Bangladesh and refers not to use the antimicrobial drugs that show insufficient sensitivity against Stap. aureus to prevent resistance and associated treatment failure. DOI: http://dx.doi.org/10.3329/bpj.v15i2.12582 Bangladesh Pharmaceutical Journal 15(2): 159-163, 2012

scholarly journals Metronidazole Resistance in Prevotella spp. and Description of a New nim Gene in Prevotella baroniae

2009 ◽  
Vol 54 (1) ◽  
pp. 60-64 ◽  
Author(s):  
C. Alauzet ◽  
F. Mory ◽  
C. Teyssier ◽  
H. Hallage ◽  
J. P. Carlier ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Prolonged Exposure ◽  
Tertiary Care ◽  
Single Copy ◽  
Clinical Isolates ◽  
Teaching Hospitals ◽  
Rrna Gene ◽  
Prolonged Incubation ◽  
Sequence Elements ◽  
High Level

ABSTRACT Nonduplicate clinical isolates of Prevotella spp. recovered from patients hospitalized between 2003 and 2006 in two French tertiary-care teaching hospitals were investigated for their susceptibility to metronidazole and the presence of nim genes. Of the 188 strains tested, 3 isolates displayed reduced susceptibility to metronidazole after 48 h of incubation, while 27 additional isolates exhibited heterogeneous resistance after prolonged incubation; all 30 of the isolates were nim negative. Among the remaining 158 isolates, 7 nim-positive isolates were detected. All of these strains were identified as Prevotella baroniae by 16S rRNA gene sequence analysis and contained a new nim gene, named nimI, as determined by DNA sequence analysis. Chromosomal localization of this single-copy gene was demonstrated in all clinical isolates as well as in type strain P. baroniae DSM 16972 by using Southern hybridization. No known associated insertion sequence elements were detected upstream of the nimI gene in any of the nim-positive strains by PCR mapping. After prolonged exposure to metronidazole, stable resistant subpopulations could be selected in nimI-positive Prevotella isolates (n = 6) as well as in nim-negative Prevotella isolates (n = 6), irrespective of their initial susceptibility to this antibiotic. This study is the first description of a new nitroimidazole resistance gene in P. baroniae which seems to be silent and which might be intrinsic in this species. Moreover, our findings highlight the fact that high-level resistance to metronidazole may be easily induced in both nim-positive and nim-negative Prevotella sp. strains.

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