tetracycline and Acinetobacter-Infections

Topics: Acinetobacter Infections; Anti-Bacterial Agents; Antifungal Agents; Clostridium Infections; Corynebacterium; Drug Synergism; Enteritis; Erythromycin; Escherichia coli Infections; Female; Humans; Infections; Mycobacterium Infections; Mycoses; Neomycin; Penicillins; Respiratory Tract Infections; Staphylococcal Infections; Streptococcal Infections; Streptomycin; Tetracycline; Vaginitis

Acinetobacter baumannii causes high mortality in ventilator-associated pneumonia patients, and antibiotic treatment is compromised by multidrug-resistant strains resistant to β-lactams, carbapenems, cephalosporins, polymyxins, and tetracyclines. Among COVID-19 patients receiving ventilator support, a multidrug-resistant A. baumannii secondary infection is associated with a 2-fold increase in mortality. Here, we investigated the use of the 8-hydroxyquinoline ionophore PBT2 to break the resistance of A. baumannii to tetracycline class antibiotics.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; beta-Lactams; Carbapenems; COVID-19; Drug Resistance, Multiple, Bacterial; Humans; Mice; Microbial Sensitivity Tests; Pandemics; Pneumonia, Ventilator-Associated; Tetracycline; Tigecycline; Zinc

To analyse the genome sequences of four archival Acinetobacter nosocomialis clinical isolates (designated AC13, AC15, AC21 and AC25) obtained from Terengganu, Malaysia in 2011 to determine their genetic relatedness and basis of antimicrobial resistance.. Antimicrobial susceptibility profiles of the A. nosocomialis isolates were determined by disk diffusion. Genome sequencing was performed using the Illumina NextSeq platform.. Genome sequencing of A. nosocomialis isolates led to the discovery of two novel plasmids, one of which encodes the tetA(39) tetracycline-resistant gene in a mobile pdif module. The high degree of genetic relatedness among the three tetracycline-resistant A. nosocomialis isolates is indicative of nosocomial transmission.

Topics: Acinetobacter; Acinetobacter Infections; Anti-Bacterial Agents; Cefotaxime; Cross Infection; Genomics; Humans; Malaysia; Nucleotides; Phylogeny; Plasmids; Tetracycline

The susceptibility of Acinetobacter baumannii exposed to primary antibiotic can be either increased or decreased when exposed to secondary antibiotic. This study was designed to assess the relative fitness, collateral susceptibility and collateral resistance of polymyxin B- (PMB-) adapted A. baumannii to ciprofloxacin (CIP), meropenem (MER), PMB, tetracycline (TET) and tobramycin (TOB). Strains of wild-type A. baumannii KACC 12454 (AB

Topics: Acinetobacter baumannii; Acinetobacter Infections; Adaptation, Biological; Anti-Bacterial Agents; beta-Lactamases; Ciprofloxacin; Drug Collateral Sensitivity; Drug Resistance, Multiple, Bacterial; Humans; Meropenem; Microbial Sensitivity Tests; Polymyxin B; Tetracycline; Tobramycin

Acinetobacter baumannii has emerged as one of the major nosocomial pathogens implicated in variety of severe infections and mortality. It is rapidly developing multi-drug resistance and also possesses surface colonization ability, which make it most difficult to treat through traditional antibiotics. This is an extensive study to describe the antibacterial activity of bacteriagenic silver nanoparticles (AgNPs) against A. baumannii AIIMS 7 in planktonic and biofilm mode. Minimum inhibitory concentration of antibiotics were in the range of 1 to 4096 μg/ml whereas AgNPs inhibited planktonic bacteria at concentration of 16 μg/ml. Fractional inhibitory concentration index revealed the synergistic interaction of AgNPs with doxycycline, tetracycline and erythromycin. Nanoparticles exhibited significant biofilm disruption activity with minimum biofilm eradication concentration of 2 mg/ml. Eradication of mature biofilm was enhanced on exposure to combination of AgNPs and antibiotics. These nanoparticles affected bacterial growth and distorted cellular morphology. Intracellular oxidative stress, induced in presence of AgNPs, also rendered bacteria susceptible to killing by nanoparticles. Besides this, AgNPs were found to interact with thiol-groups, which indicate their potential to interact with cellular proteins to exhibit antimicrobial activity.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Anti-Bacterial Agents; Cross Infection; Doxycycline; Metal Nanoparticles; Microbial Sensitivity Tests; Silver; Tetracycline

The increasing resistance of Acinetobacter baumannii to antibiotics has recently been regarded as a notable therapeutic difficulty. Evaluating resistance rates of some A. baumannii isolates to tetracyclines had an impact on understanding the antibiotic resistance dissemination. By comparing genetic characteristics and relatedness of A. baumannii isolates, we are able to determine the transition dynamics of outbreak isolates.. A total of 72 non-duplicate isolates of A. baumannii were recovered in 2011 and 2015 and minimum inhibitory concentration (MIC) range distribution of the isolates to tetracyclines was performed by broth micro dilution (BMD) assay, and to determine the lineage relatedness of the outbreak isolates repetitive extragenic palindromic element based on polymerase chain reaction (rep-PCR) and international clonal (ICs) investigations were performed.. Resistance rates to tetracycline, doxycycline and minocycline in 2011 were 73, 2 and 0%, while these rates in 2015 increased up to 90, 84 and 52%, respectively. The tetB existed in 100% of all the isolates of both years. tetA was not found in any of the isolates. According to the rep-PCR assays, up to 83% of all isolates clustered distinctly and only 6% of isolates had a common root. The percentage rates of IC1 decreased from 42% in 2011 to 22% in 2015, while those of IC2 increased from 28 to 36%, from 2011 to 2015.. Our data showed that resistance to the first and second generations of tetracyclines is on the rise and the clonal transition dynamics of isolates are in progress in our hospital.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Anti-Bacterial Agents; Bacterial Proteins; beta-Lactamases; Drug Resistance, Multiple, Bacterial; Humans; Iran; Microbial Sensitivity Tests; Molecular Epidemiology; Tetracycline

Acinetobacter baumannii is considered an important nosocomial pathogen worldwide owing to its increasing antibiotic resistance. This study aimed to determine the complete genome sequence of A. baumannii strain A1296 and to perform a comparative analysis among A. baumannii.. The complete genome sequence of A. baumannii A1296 was sequenced on two SMRT cells using P6C4 chemistry on a PacBio Single Molecule, Real-Time (SMRT) RS II instrument. The A1296 genome sequence was annotated using Prokaryotic Genome Automatic Annotation Pipeline (PGAAP), and the sequence type and resistance genes of the strain were analysed.. Here we present the complete genome sequence of A. baumannii strain A1296, belonging to a novel sequence type (ST1469) and isolated from patient in China, that was sensitive to multiple antibiotics. The genome of A. baumannii A1296 was 3810701bp in length, including one circular chromosome and two plasmids. The tet(39) resistance gene was located on the small plasmid in this A. baumannii strain.. The genome sequence of A. baumannii strain A1296 can be used as a reference sequence for comparative analysis aimed at elucidating the acquisition, dissemination and mobilisation of resistance genes among A. baumannii.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Cerebral Hemorrhage; China; Drug Resistance, Multiple, Bacterial; Genome, Bacterial; Humans; Microbial Sensitivity Tests; Molecular Sequence Annotation; Plasmids; Sequence Analysis, DNA; Tetracycline

Adaptive antibiotic resistance is a newly described phenomenon by which Acinetobacter baumannii induces efflux pump activity in response to host-associated environmental cues that may, in part, account for antibiotic treatment failures against clinically defined susceptible strains. To that end, during adaptation to growth in human serum, the organism induces approximately 22 putative efflux-associated genes and displays efflux-mediated minocycline tolerance at antibiotic concentrations corresponding to patient serum levels. Here, we show that in addition to minocycline, growth in human serum elicits A. baumannii efflux-mediated tolerance to the antibiotics ciprofloxacin, meropenem, tetracycline, and tigecycline. Moreover, using a whole-cell high-throughput screen and secondary assays, we identified novel serum-associated antibiotic efflux inhibitors that potentiated the activities of antibiotics toward serum-grown A. baumannii. Two compounds, Acinetobacter baumannii efflux pump inhibitor 1 (ABEPI1) [(E)-4-((4-chlorobenzylidene)amino)benezenesulfonamide] and ABEPI2 [N-tert-butyl-2-(1-tert-butyltetrazol-5-yl)sulfanylacetamide], were shown to lead to minocycline accumulation within A. baumannii during serum growth and inhibit the efflux potential of the organism. While both compounds also inhibited the antibiotic efflux properties of the bacterial pathogen Pseudomonas aeruginosa, they did not display significant cytotoxicity toward human cells or mammalian Ca(2+) channel inhibitory effects, suggesting that ABEPI1 and ABEPI2 represent promising structural scaffolds for the development of new classes of bacterial antibiotic efflux pump inhibitors that can be used to potentiate the activities of current and future antibiotics for the therapeutic intervention of Gram-negative bacterial infections.

Topics: Acetamides; Acinetobacter baumannii; Acinetobacter Infections; Anti-Bacterial Agents; Biological Transport; Calcium Channels; Cell Line; Ciprofloxacin; Drug Resistance, Multiple, Bacterial; HEK293 Cells; Humans; Membrane Transport Proteins; Meropenem; Microbial Sensitivity Tests; Minocycline; Pseudomonas aeruginosa; Sulfonamides; Tetracycline; Tetrazoles; Thienamycins; Tigecycline

Nonmammalian model systems of infection such as Galleria mellonella (caterpillars of the greater wax moth) have significant logistical and ethical advantages over mammalian models. In this study, we utilize G. mellonella caterpillars to study host-pathogen interactions with the gram-negative organism Acinetobacter baumannii and determine the utility of this infection model to study antibacterial efficacy. After infecting G. mellonella caterpillars with a reference A. baumannii strain, we observed that the rate of G. mellonella killing was dependent on the infection inoculum and the incubation temperature postinfection, with greater killing at 37 degrees C than at 30 degrees C (P = 0.01). A. baumannii strains caused greater killing than the less-pathogenic species Acinetobacter baylyi and Acinetobacter lwoffii (P < 0.001). Community-acquired A. baumannii caused greater killing than a reference hospital-acquired strain (P < 0.01). Reduced levels of production of the quorum-sensing molecule 3-hydroxy-C(12)-homoserine lactone caused no change in A. baumannii virulence against G. mellonella. Treatment of a lethal A. baumannii infection with antibiotics that had in vitro activity against the infecting A. baumannii strain significantly prolonged the survival of G. mellonella caterpillars compared with treatment with antibiotics to which the bacteria were resistant. G. mellonella is a relatively simple, nonmammalian model system that can be used to facilitate the in vivo study of host-pathogen interactions in A. baumannii and the efficacy of antibacterial agents.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Disease Models, Animal; Host-Pathogen Interactions; Moths; Quorum Sensing; Virulence

A total of 49 unique clinical isolates of multidrug-resistant (MDR) Acinetobacter baumannii identified at a tertiary medical center in Pittsburgh, Pennsylvania, between August 2006 and September 2007 were studied for the genetic basis of their MDR phenotype. Approximately half of all A. baumannii clinical isolates identified during this period qualified as MDR, defined by nonsusceptibility to three or more of the antimicrobials routinely tested in the clinical microbiology laboratory. Among the MDR isolates, 18.4% were resistant to imipenem. The frequencies of resistance to amikacin and ciprofloxacin were high at 36.7% and 95.9%, respectively. None of the isolates was resistant to colistin or tigecycline. The presence of the carbapenemase gene bla(OXA-23) and the 16S rRNA methylase gene armA predicted high-level resistance to imipenem and amikacin, respectively. bla(OXA-23) was preceded by insertion sequence ISAba1, which likely provided a potent promoter activity for the expression of the carbapenemase gene. The structure of the transposon defined by ISAba1 differed from those reported in Europe, suggesting that ISAba1-mediated acquisition of bla(OXA-23) may occur as an independent event. Typical substitutions in the quinolone resistance-determining regions of the gyrA and parC genes were observed in the ciprofloxacin-resistant isolates. Plasmid-mediated quinolone resistance genes, including the qnr genes, were not identified. Fifty-nine percent of the MDR isolates belonged to a single clonal group over the course of the study period, as demonstrated by pulsed-field gel electrophoresis.

Topics: Academic Medical Centers; Acinetobacter baumannii; Acinetobacter Infections; Amikacin; Base Sequence; beta-Lactamases; Cross Infection; DNA Primers; Drug Resistance, Multiple, Bacterial; Electrophoresis, Gel, Pulsed-Field; Genes, Bacterial; Humans; Microbial Sensitivity Tests; Molecular Epidemiology; Pennsylvania; Polymerase Chain Reaction

The presence of tetracycline (TET) resistance genes was investigated in 49 genotypically related and unrelated multidrug-resistant Acinetobacter baumannii (MDRAB) strains from European hospitals including representatives of pan-European clones I and II. Except for one strain, all MDRAB strains displayed resistance to tetracycline (MIC range of 16 to > 512 microg/ml) but were susceptible (MIC < 4 microg/ml) or exhibited intermediate resistance (MIC of 4-8 microg/ml) to minocycline (MIN). In 37 strains, either tet(A) or tet(B) was detected and one of these strains possessed both tet(A) and tet(M). In addition, all MDRAB strains contained the aspecific efflux gene adeB irrespectively of whether they harbored tet genes or not. Repetitive DNA element (rep)-PCR fingerprinting using the (GTG)5 primer [(GTG)5-PCR] revealed that strains previously assigned to pan-European clones I and II were grouped into two separate clusters. In addition, these clusters also contained strains that had not been typed previously, indicating that (GTG)5-PCR is a valuable method for recognizing putative new members of MDRAB clones. Most, but not all, members of clones I and II were linked to the presence of either tet(A) or tet(B) and displayed different levels of TET resistance with MIC values of 32 to > 512 microg/ml and > 512 microg/ml, respectively. Of these two genes only tet(B) encodes an efflux of both TET and MIN, which was reflected by the relatively high MIC values for MIN (4 microg/ml) shown by the majority of the tet(B)-carrying clone II strains as opposed to the low MIC values for MIN (< 1 microg/ml) displayed by most tet(A)-containing clone I strains. Collectively, our phenotypic and genotypic resistance data support the therapeutic evaluation of second-generation tetracyclines like MIN as promising agents for treating MDRAB infections.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Antiporters; Bacterial Proteins; Cluster Analysis; DNA Fingerprinting; DNA Restriction Enzymes; DNA, Bacterial; Drug Resistance, Multiple, Bacterial; Humans; Membrane Transport Proteins; Microbial Sensitivity Tests; Minocycline; Polymerase Chain Reaction; Repetitive Sequences, Nucleic Acid; Tetracycline; Tetracycline Resistance

Following characterisation by phenotypic tests and amplified ribosomal DNA restriction analysis (ARDRA), 50 tetracycline-resistant (MIC > or = 16 mg/L) Acinetobacter strains from clinical (n = 35) and aquatic (n = 15) samples were analysed by PCR for tetracycline resistance (Tet) determinants of classes A-E. All the clinical strains were A. baumannii; most (33 of 35) had Tet A (n = 16) or B (n = 17) determinants, and only two did not yield amplicons with primers for any of the five tetracycline resistance determinants. The aquatic strains belonged to genomic species other than A. baumannii, and most (12 of 15) did not contain determinants Tet A-E. Strains negative for Tet A-E were also negative for Tet G and M; further analysis of two aquatic strains with specific primers for Tet O and Tet Y and degenerate primers for Tet M-S-O-P(B)-Q also showed negative results. Transfer of tetracycline resistance was tested for 20 strains with three aquatic Acinetobacter strains and Escherichia coli K-12 as recipients. Transfer of resistance was demonstrated between aquatic strains from distinct ecological niches, but not from clinical to aquatic strains, nor from any Acinetobacter strain to E. coli K-12. Most transconjugants acquired multiple relatively small plasmids (<36 kb). Transfer did not occur when DNA from the donor strains was added to the recipient cultures and was not affected by deoxyribonuclease I, suggesting a conjugative mechanism. It is concluded that Tet A and B are widespread among tetracycline-resistant A. baumannii strains of clinical origin, but unknown genetic determinants are responsible for most tetracycline resistance among aquatic Acinetobacter spp. These differences, together with the inability of clinical strains to transfer tetracycline resistance in vitro to aquatic strains, contra-indicate any important flow of tetracycline resistance genes between clinical and aquatic acinetobacter populations.

Topics: Acinetobacter; Acinetobacter Infections; Anti-Bacterial Agents; DNA Primers; DNA Restriction Enzymes; DNA, Ribosomal; Drug Resistance, Microbial; Electrophoresis, Agar Gel; Gene Transfer Techniques; Humans; Plasmids; Polymerase Chain Reaction; Tetracycline; Tetracycline Resistance; Water Microbiology

Topics: Acinetobacter; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Mice; Mice, Inbred Strains; Microbial Sensitivity Tests; Tetracycline; Virulence

Of eight patients with Gram-negative bacillary sternoarticular pyoarthrosis, seven were long-term intravenous heroin abusers. Clinical onset was insidious and a long delay (one month or more) in seeking hospitalization was usually noted. Anterior chest discomfort and painful, restricted homolateral shoulder motion were the chief complaints. Fever and monoarticular arthritis were universally present, Open synovial biopsy examination was frequently required for etiologic diagnosis. Pseudomonas aeruginosa was the most common pathogen isolated. Roentgenographic evidence of associated osteomyelitis was usually seen, but tomography was often necessary to delineate this lesion. Intraoperatively, associated osteomyelitis of the clavicular head and/or sternum was present in all eight cases and a perisynovial and/or retrosternal abscess was found in five patients. Early surgical exploration and prolonged antimicrobial therapy yielded excellent results.

Topics: Acinetobacter Infections; Adult; Arthritis, Infectious; Bacterial Infections; Bacteroides Infections; Carbenicillin; Drainage; Female; Gentamicins; Gram-Negative Aerobic Bacteria; Humans; Male; Pseudomonas Infections; Ribs; Sternoclavicular Joint; Sternocostal Joints; Synovial Fluid; Tetracycline; Tomography, X-Ray

An 11-year-old girl had hyperacute conjunctivitis but was lost to follow-up until nine days later when she returned with a corneal perforation and iris prolapse. A smear at that time showed Gram-negative intracellular diplococci, but subsequent bacteriological study revealed the causative organism to be Mima polymorpha. This apparently is the first documented case of corneal perforation due to Mimeae, and emphasizes that Mimeae can be completely indistinguishable, clinically and on smear, from infection caused by Neisseria. Only a high index of suspicion and the proper bacterial cultures can prevent a possible tragic misdiagnosis.

Topics: Acinetobacter Infections; Child; Conjunctivitis; Eye Diseases; Female; Humans; Iris; Keratitis; Microbial Sensitivity Tests; Penicillin G; Tetracycline

Topics: Acinetobacter; Acinetobacter Infections; Adult; Antibiosis; Diagnosis, Differential; Female; Gentamicins; Humans; Meningoencephalitis; Penicillin Resistance; Penicillins; Sulfonamides; Tetracycline