Discovery of ANT3310, a Novel Broad-Spectrum Serine ß-Lactamase Inhibitor of the Diazabicyclooctane Class, Which Strongly Potentiates Meropenem Activity against Carbapenem-Resistant Enterobacterales and Acinetobacter baumannii.

The diazabicyclooctanes (DBOs) are a class of serine ß-lactamase (SBL) inhibitors that use a strained urea moiety as the warhead to react with the active serine residue in the active site of SBLs. The first in-class drug, avibactam, as well as several other recently approved DBOs (e.g., relebactam) or those in clinical development (e.g., nacubactam and zidebactam) potentiate activity of ß-lactam antibiotics, to various extents, against carbapenem-resistant Enterobacterales (CRE) carrying class A, C, and D SBLs; however, none of these are able to rescue the activity of ß-lactam antibiotics against carbapenem-resistant Acinetobacter baumannii (CRAB), a WHO "critical priority pathogen" producing class D OXA-type SBLs. Herein, we describe the chemical optimization and resulting structure-activity relationship, leading to the discovery of a novel DBO, ANT3310, which uniquely has a fluorine atom replacing the carboxamide and stands apart from the current DBOs in restoring carbapenem activity against OXA-CRAB as well as SBL-carrying CRE pathogens.

In-Vitro Assessment Of The Therapeutic Potential Of Polymyxins And Tigecycline Against Multidrugresistant Acinetobacter Isolates From Infected Wounds.

BACKGROUND: The incidence of multidrug-resistant (MDR), extreme drug resistant (XDR), and pan drug-resistant (PDR) Acinetobacter are increasing throughout the world. The therapeutic management and control of Acinetobacter are difficult due to the emergence of drug resistance and its enduring capacity to survive in the environment. The present study was designed to appraise the efficacy of Polymyxins and Tigecycline against multidrugresistant Acinetobacter isolates from surgical and burn wounds. METHODS: During the study, the specimens were collected from various types of wounds from inpatients and outpatients of the tertiary care hospitals of Lahore, Pakistan in 2017 and 2018. The bacterial pathogens were isolated and identified using standard microbiological procedures and molecular confirmation of Acinetobacter species was examined by PCR using specific primers. The antibiotic susceptibility profiling of Acinetobacter isolates was studied against 18 antibiotics as per Clinical and Laboratory Standards Institute (CLSI) guidelines. RESULTS: The Acinetobacter isolates demonstrated extreme resistance especially to ampicillin/sulbactam, piperacillin/tazobactam, cephalosporins, carbapenems, fluoroquinolones, and aminoglycosides. However, the colistin, polymyxin, and tigecycline remained the most effective antimicrobial agents against Acinetobacter isolates. CONCLUSIONS: The results highlight the extent of drug resistance and therapeutic potential of Polymyxins and Tigecycline for wound infections caused by MDR and XDR Acinetobacter species. The wiser use of antimicrobials, incessant surveillance of antimicrobial resistance, and stringent adherence to infection control guidelines are critical to reducing major outbreaks in the future.

Polyarthritis Caused by Acinetobacter kookii in a Rothschild's Giraffe Calf (Giraffa camelopardalis rothschildi).

We report the first isolation of Acinetobacter kookii from a Rothschild's giraffe calf (Giraffa camelopardalis rothschildi) that had severe polyarthritis. The isolate was resistant to more than one representative of each of four classes of antibiotics (penicillins, macrolides, lincosamides and tetracyclines). As A. kookii has not been previously associated with disease in humans or animals, it may be an emerging opportunistic pathogen posing a threat to immunocompromised patients. Furthermore, as transmission of Acinetobacter spp. with similar patterns of antimicrobial resistance has been previously reported in human and animal populations, special care should be taken when handling infected animals.

Multicentre study of risk factors for mortality in patients with Acinetobacter bacteraemia receiving colistin treatment.

Colistin remains a last-line antibiotic for the treatment of infections by multidrug-resistant Acinetobacter species. However, mortality rates are high in patients with Acinetobacter infection receiving colistin treatment. This multicentre study evaluated whether colistin susceptibility, additional antimicrobial agents or other prognostic factors influenced the clinical outcomes of patients receiving colistin treatment for Acinetobacter bacteraemia. This retrospective study enrolled 122 adults receiving colistin for monomicrobial Acinetobacter bacteraemia at six medical centres in the ACTION Study Group over an 8-year period. Clinical information, antimicrobial susceptibility and colistin resistance determinants were analysed. The primary outcome measure was 14-day mortality. Among 122 patients, 18 and 104 were infected with colistin-resistant (ColR) isolates [minimum inhibitory concentration (MIC) ≥4 mg/L] and colistin-susceptible (ColS) isolates (MIC ≤2 mg/L), respectively. Patients infected with ColR and ColS isolates did not differ significantly with regard to Charlson comorbidity index, invasive procedures, sources of bacteraemia, disease severity and 14-day mortality rate (44.4% vs. 34.6%; P = 0.592). No specific additional antimicrobial agent was independently associated with higher or lower mortality. Coronary artery disease, higher Acute Physiology and Chronic Health Evaluation (APACHE) II score and bacteraemia caused Acinetobacter baumannii were independent risk factors associated with 14-day mortality. Mechanisms of colistin resistance were associated with amino acid variants in the pmrCAB operon. Finally, previously unreported Acinetobacter nosocomialis amino acid variants related to colistin resistance were identified. In conclusion, colistin susceptibility and colistin combination antimicrobial treatment were not associated with decreased 14-day mortality in patients with Acinetobacter bacteraemia receiving colistin treatment.

Comparison of two therapeutic approaches for the management of ventilator-associated pneumonia due to multidrug-resistant Acinetobacter: a randomized clinical trial study.

Management of ventilator-associated pneumonia (VAP) is a puzzling issue for infectious disease specialist. The present clinical trial study was aimed to comparing the effects of injectable colistin plus nebulized colistin and injectable colistin plus nebulized tobramycin on management of patients with VAP due to multidrug-resistant Acinetobacter. VAP patients were randomly divided into two groups (n = 30/each): Group 1 - patients that received intravenous (IV) meropenem, injectable colistin plus nebulized colistin, as a routine treatment, and Group 2 - patients that received IV meropenem, injectable colistin plus nebulized tobramycin. A total of 14 days of therapeutic intervention are required for every case. Follow-up for subjects was performed at five time-points: days 1, 3, 5, 7, and 14 after intervention. Also, a mean of creatinine levels of patients was determined in five times. In the present study, the clinical pulmonary infection score (CPIS) was determined on the basis of points assigned for various clinically manifestations of VAP. Based on our statistical analysis, there was no significant difference between CPIS and creatinine level in both Groups 1 and 2 (p > .05). CPIS and other clinical investigation appeared effectiveness of the treatment with injected colistin plus nebulized tobramycin; on the other hand, the results of present clinical trial showed that aforementioned therapeutic approach can be used as an alternative treatment for the management of infection in VAP patients.

Characterization of Terpene Synthase from Tea Green Leafhopper Being Involved in Formation of Geraniol in Tea (Camellia sinensis) Leaves and Potential Effect of Geraniol on Insect-Derived Endobacteria.

When insects attack plants, insect-derived elicitors and mechanical damage induce the formation and emission of plant volatiles that have important ecological functions and flavor properties. These events have mainly been studied in model plants, rather than crop plants. Our study showed that tea green leafhopper (Empoasca (Matsumurasca) onukii Matsuda), a major pest infesting tea attack significantly induced the emission of geraniol from tea leaves, but did not affect the crude enzyme activity of geraniol synthase in tea leaves. An enzyme extract of E. (M.) onukii specifically produced geraniol from geraniol diphosphate. Furthermore, a terpene synthase (EoTPS) was isolated from E. (M.) onukii. This terpene synthase was able to convert geraniol diphosphate to geraniol in vitro. In addition, geraniol had in vitro ability to inhibit the growth of Acinetobacter johnsonii that is endobacterial isolated from E. (M.) onukii. This information illustrates that elicitors from piercing-sucking insects can induce the formation of volatiles from crop plants and advances our understanding of the roles of plant volatiles in the interaction among crops-insects-microorganisms.

Molecular epidemiology & therapeutic options of carbapenem-resistant Gram-negative bacteria.

Background & objectives: The growing incidence and the wide diversity of carbapenemase-producing bacterial strains is a major concern as only a few antimicrobial agents are active on carbapenem-resistant bacteria. This study was designed to study molecular epidemiology of carbapenem-resistant Gram-negative bacterial (GNB) isolates from the community and hospital settings. Methods: In this study, non-duplicate GNB were isolated from clinical specimens, and phenotypic test such as modified Hodge test, metallo ß-lactamase E-strip test, etc. were performed on carbapenem-resistant bacteria. Multiplex PCR was performed to identify the presence of blaIMP, blaVIM, blaKPC, blaOXA48, blaOXA23, blaSPM, blaGIM, blaSIM and blaNDM. Minimum inhibitory concentration (MIC) of colistin, fosfomycin, minocycline, chloramphenicol and tigecycline was also determined. Results: Of the 3414 GNB studied, carbapenem resistance was 9.20 per cent and maximum resistance (11.2%) was present at tertiary care centre, followed by secondary care (4%) and primary centre (2.1%). Among the carbapenem-resistant bacteria, overall, the most common isolate was Pseudomonas aeruginosa (24%). On multiplex PCR 90.3 per cent carbapenem-resistant isolates were positive for carbapenemase gene. The blaNDM(63%) was the most prevalent gene followed by blaVIM(18.4%). MIC results showed that 88 per cent carbapenem-resistant Enterobacteriaceae were sensitive to fosfomycin, whereas 78 per cent of P. aeruginosa and 85 per cent Acinetobacter spp. were sensitive to colistin. Interpretation & conclusions: Carbapenem resistance in GNB isolates from the community and hospital settings was found to be on the rise and should be closely monitored. In the absence of new antibiotics in pipeline and limited therapeutic options, prudent use of antibiotics and strict infection control practices should be followed in hospital to limit the emergence and spread of multidrug-resistant bacteria.

Molecular Epidemiology of Emerging Carbapenem Resistance in Acinetobacter nosocomialis and Acinetobacter pittii in Taiwan, 2010 to 2014.

This study investigated the molecular epidemiology of carbapenem-resistant Acinetobacter nosocomialis and Acinetobacter pittii (ANAP). Clinical isolates of Acinetobacter spp. collected by the biennial nationwide Taiwan Surveillance of Antimicrobial Resistance program from 2010 to 2014 were subjected to species identification, antimicrobial susceptibility testing, and PCR for detection of carbapenemase genes. Whole-genome sequencing or PCR mapping was performed to study the genetic surroundings of the carbapenemase genes. Among 1,041 Acinetobacter isolates, the proportion of ANAP increased from 11% in 2010 to 22% in 2014. The rate of carbapenem resistance in these isolates increased from 7.5% (3/40) to 22% (14/64), with a concomitant increase in their resistance to other antibiotics. The blaOXA-72 and blaOXA-58 genes were highly prevalent in carbapenem-resistant ANAP. Various genetic structures were found upstream of blaOXA-58 in different plasmids. Among the plasmids found to contain blaOXA-72 flanked by XerC/XerD, pAB-NCGM253-like was identified in 8 of 10 isolates. Conjugations of plasmids carrying blaOXA-72 or blaOXA-58 to A. baumannii were successful. In addition, three isolates with chromosome-located blaOXA-23 embedded in AbGRI1-type structure with disruption of genes other than comM were detected. Two highly similar plasmids carrying class I integron containing blaIMP-1 and aminoglycoside resistance genes were also found. The universal presence of blaOXA-272/213-like on A. pittii chromosomes and their lack of contribution to carbapenem resistance indicate its potential to be a marker for species identification. The increase of ANAP, along with their diverse mechanisms of carbapenem resistance, may herald their further spread and warrants close monitoring.

Overexpression of AdeABC efflux pump associated with tigecycline resistance in clinical Acinetobacter nosocomialis isolates.

OBJECTIVES: Tigecycline non-susceptible Acinetobacter nosocomialis (TNAN) has been discovered in clinical isolates. The resistance-nodulation-cell division (RND)-type efflux system plays a major role in tigecycline non-susceptible Acinetobacter baumannii, but the mechanism in A. nosocomialis remains unknown. Our aim was to analyse the contribution of efflux-based tigecycline resistance in clinical A. nosocomialis isolates collected from multiple medical centres in Taiwan. METHODS: A total of 57 A. nosocomialis isolates, including 46 TNAN and 11 tigecycline-susceptible A. nosocomialis (TSAN) isolates, were analysed. Of these, 46 TNAN isolates were clustered to ST410 (43 isolates) and ST68 (three isolates) by multi-locus sequence typing. RESULTS: The relationship between the RND efflux pump and tigecycline resistance was indirectly verified by successfully reducing tigecycline resistance with NMP, an efflux pump inhibitor. The three RND efflux systems (AdeABC, AdeIJK and AdeFGH) were detected in all clinical isolates. The transcript level of adeB gene increased significantly and was correlated with tigecycline resistance. Moreover, the AdeRS two-component system was further classified into four different types of AdeRS patterns considering the amino acid sequence. Further analysis showed that tigecycline resistance was related to the transcript level of adeB gene and the AdeRS pattern. CONCLUSION: This study showed that the dissemination of TNAN isolates in Taiwan is attributable mainly to the spread of ST410. The AdeABC efflux pump appeared to play an important role in the tigecycline resistance of A. nosocomialis.

Acinetobacter Spp: Resistance and therapeutic decisions at the turn of the novel millennium.

This study was planned to evaluate sample wise isolation and antimicrobial resistant trends of Acinetobacter spp in different departments of a tertiary care hospital. This was a transversal descriptive study, carried out in the clinical microbiology laboratory of the Allama Iqbal Medical College/ Jinnah Hospital, Lahore, Pakistan, during the period of January 2015 to December 2016. Every clinical specimen was processed for bacterial culture and antimicrobial susceptibly testing. A total of 3590 (2015=1780, 2016=1810) clinical specimens were processed. Of the total, only 54.7% were gram-negative, among these Acinetobacter spp were isolated from 10.1% and 16.5% samples respectively in 2015-16 with an overall rate of 24.3%. The highest occurrence of Acinetobacter spp isolates was reported from Intensive care units (ICU) (54%) followed by surgical units (25%) and medical units (16%). It is noteworthy that ICU and internal medicine showed the highest resistance rates, whereas, lower resistance rate was observed for the outdoor patients (OPD). Although collistin showed 0% resistant while ceftriaxone, ciprofloxacin, gentamicin, and tigecycline showed 90%, 68%, 66%, 66% and 62% resistance against Acinetobacter spp. respectively. An alarming increase in the resistance rate of meropenem, cefoperazone/sulbactam, piperacillin/ tazobactam, ciprofloxacin, and imipenem was observed from the year 2015 to 2016. This startling resistance acquired by Acinetobacter spp. within a period of one year, represent very limited therapeutic options left for the infections caused by Acinetobacter spp. Unavailability of effective drugs and limited therapeutic options enforce the health care practitioners to prescribe expensive and broad range antibiotics, which may cause harm to the patient. Therefore, it is need of an hour to better understand the antimicrobial patterns and optimize antimicrobial prescription policies for the control of multidrug-resistant Acinetobacter spp.

Application of Illumina-MiSeq high throughput sequencing and culture-dependent techniques for the identification of microbiota of silver carp (Hypophthalmichthys molitrix) treated by tea polyphenols.

This study evaluated the antimicrobial effects of tea polyphenols (TP) on changes in microbiota composition and quality attributes in silver carp fillets stored at 4 °C. During storage, TP treatment was found to be effective in enhancing sensory quality, inhibiting microbial growth, and attenuating chemical quality deterioration. Meanwhile, the composition of microbiota of silver carp fillets was investigated using culture-dependent and culture-independent methods. Initially, compared to the control, TP obviously decreased the relative abundance of Aeromonas, which allowed Acinetobacter and Methylobacterium to become the dominant microbiota in TP treated fillets on day 0. The controls, 0.5% TP-treated fillets, and 1% TP-treated fillets were rejected by sensory panelists on days 8, 12, and 12, respectively. At the time of sensory rejection, Aeromonas, followed by Acinetobacter and Pseudomonas, became the main spoilers in the control on day 8. However, TP treatment inhibited the growth of Aeromonas and Acinetobacter significantly. Consequently, Aeromonas followed by Pseudomonas and Shewanella became the predominant microbiota in all TP-treated fillets on day 12. Therefore, TP improved the quality of fillets during chilled storage, which was mainly due to their modulating effects on microbiota that resulted in the change in pattern and process of spoilage in fillets.

Antimicrobial effect of copper alloys on Acinetobacter species isolated from infections and hospital environment.

Background: An increased proportion of Gram-negative bacteria have recently been reported among etiologic agents of infection. In Poland, Acinetobacter baumannii is a big problem for hospitals, especially intensive care units. Touch surfaces made from materials with antimicrobial properties, especially copper alloys, are recommended as a supplementary method of increasing biological safety in the hospital environment. Aim of the study: The objective of this study is to determine the susceptibility to selected copper alloys of three clinical Acinetobacter baumannii strains, one Acinetobacter lwoffi and an A. pittii strain isolated from the hospital environment. Material and method: The modification of the Japanese Standard, which the ISO 22196:2011 norm was used for testing antimicrobial properties of CuZn37, CuSn6 and CuNi18Zn20 and Cu-ETP and stainless steel as positive and negative control, respectively. Results: The highest cidal efficiency, expressed as both time and the degree of reduction of the initial suspension density, against all of the tested Acinetobacter strains was found for ETP copper. But, the results of our study also confirmed effective activity (bacteriocidal or bacteriostatic) of copper alloys selected for the study, contrary to the stainless steel. The reduction in bacterial suspension density is significantly different depending on the strain and copper alloy composition. Conslusions: The results of our study confirmed the effective antibacterial activity of copper and its selected alloys against clinical Acinetobacter baumannii and Acinetobacter lwoffii strains, and Acinetobacter pittii strain isolated from the hospital environment.

Uncommon carbapenemase-encoding plasmids in the clinically emergent Acinetobacter pittii.

OBJECTIVES: Two carbapenemase-carrying plasmids, pLS488 (blaOXA-23) and pLS535 (blaOXA-58) from Acinetobacter pittii clinical isolates, were characterized in this study, including their ability to be transferred to Acinetobacter baumannii. METHODS: The clinical isolates were obtained from drainage fluid of a patient with biliary tract cancer and from an exudate of a patient with a hip infection (Portuguese University Hospital, 2012). Isolate characterization included antimicrobial susceptibility tests, carbapenemase production by Blue-Carba, carbapenem-hydrolysing class D ß-lactamase (CHDL) gene search by PCR sequencing, ApaI-PFGE, CHDL genetic location and plasmid size by hybridization and WGS. Plasmid transfer was performed by conjugation or electroporation. RESULTS: pLS488 constitutes the first conjugative plasmid reported to carry a carbapenem resistance gene in A. pittii and is part of a potential new incompatibility group that might also account for the dissemination of OXA-23 in A. baumannii. pLS535 belongs to the Acinetobacter GR7 incompatibility group and presents a new scaffold for OXA-58. This plasmid lacked the machinery for conjugation, but was transferable by electroporation to A. baumannii. Both isolates, which displayed the same PFGE pattern, represent the first report of CHDL-carrying A. pittii in Portuguese hospitals. CONCLUSIONS: Altogether, these results emphasize the importance of A. pittii, or particular A. pittii clones, as a source of resistance genes, facilitating their dissemination among different bacterial species.

Previous Antibiotic Exposure and Antimicrobial Resistance Patterns of Acinetobacter spp. and Pseudomonas aeruginosa Isolated from Patients with Nosocomial Infections.

BACKGROUND: The alarming spread of antibiotic-resistant bacteria causing healthcare-associated infections has been extensively reported in recent medical literature. AIMS: To compare trends in antimicrobial consumption and development of resistance among isolates of Acinetobacter spp. and Pseudomonas aeruginosa that cause hospital infections. STUDY DESIGN: Cross-sectional study. METHODS: A study was conducted in a tertiary healthcare institution in central Serbia, during the 7-year period between January 2009 and December 2015. The incidence rate of infections caused by Acinetobacter or Pseudomonas, as well as their resistance density to commonly used antibiotics, were calculated. Utilization of antibiotics was expressed as the number of defined daily doses per 1000 patient-days. RESULTS: A statistically significant increase in resistance density in 2015 compared to the first year of observation was noted for Acinetobacter, but not for Pseudomonas, to third-generation cephalosporins (p=0.008), aminoglycosides (p=0.005), carbapenems (p=0.003), piperacillin/tazobactam (p=0.025), ampicillin/sulbactam (p=0.009) and tigecycline (p=0.048). CONCLUSION: Our study showed that there is an association between the resistance density of Acinetobacter spp. and utilization of carbapenems, tigecycline and aminoglycosides. A multifaceted intervention is needed to decrease the incidence rate of Acinetobacter and Pseudomonas hospital infections, as well as their resistance density to available antibiotics.

Ni(II) and Cu(II) removal from aqueous solution by a heavy metal-resistance bacterium: kinetic, isotherm and mechanism studies.

The potentiality of a heavy metal-resistance bacterium Acinetobacter sp. HK-1 for removing Ni(II) and Cu(II) ions from aqueous solution and the biosorption mechanism were investigated in this study. The effects of pH, contact time and Ni(II)/Cu(II) concentration on the adsorption process were evaluated and the maximum biosorption capacity of strain HK-1 was found to be 56.65 mg/g for Ni(II) and 157.2 mg/g for Cu(II), respectively. The experimental kinetic data fit well with the pseudo-second-order model (R2 > 0.98) and the biosorption process was best explained by the Langmuir-Freundlich dual model (R2 > 0.97). The morphologies of HK-1 before and after adsorption in a Ni(II)/Cu(II) supplemented system were compared using a scanning electron microscope. After adsorption, the valence state of Ni(II)/Cu(II) was not changed and the formation of nickel/copper phosphate was observed using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. The results of Fourier transform infrared spectroscopy and XPS further indicated that amine, phosphate and carboxyl groups were involved in the biosorption process. Cu(II) biosorption by Acinetobacter sp. was firstly reported. Based on the above results, it can be concluded that Acinetobacter sp. HK-1 has a promising application in Ni(II) and Cu(II) ion removal from industrial wastewater.

An approach to study ultrastructural changes and adaptive strategies displayed by Acinetobacter guillouiae SFC 500-1A under simultaneous Cr(VI) and phenol treatment.

Acinetobacter guillouiae SFC 500-1A, a native bacterial strain isolated from tannery sediments, is able to simultaneously remove high concentrations of Cr(VI) and phenol. In this complementary study, high-resolution microscopy techniques, such as atomic force microscopy (AFM) and transmission electron microscopy (TEM), were used to improve our understanding of some bacterial adaptive mechanisms that enhance their ability to survive. AFM contributed in gaining insight into changes in bacterial size and morphology. It allowed the unambiguous identification of pollutant-induced cellular disturbances and the visualization of bacterial cells with depth sensitivity. TEM analysis revealed that Cr(VI) produced changes mainly at the intracellular level, whereas phenol produced alterations at the membrane level. This strain tended to form more extensive biofilms after phenol treatment, which was consistent with microscopy images and the production of exopolysaccharides (EPSs). In addition, other exopolymeric substances (DNA, proteins) significantly increased under Cr(VI) and phenol treatment. These exopolymers are important for biofilm formation playing a key role in bacterial aggregate stability, being especially useful for bioremediation of environmental pollutants. This study yields the first direct evidences of a range of different changes in A. guillouiae SFC 500-1A which seems to be adaptive strategies to survive in stressful conditions.

Assessing antibiotic therapy effectiveness against the major bacterial pathogens in a hospital using an integrated index.

AIM: To assess the effectiveness of antibiotic therapy against five indicator bacteria in a Chinese hospital using an index-based approach. METHODS: The study population comprises 1031 patients who had one clinically significant bacterial isolate in 2008, 2010 and 2013. Drug resistance index (DRI) based on pathogens was calculated. RESULTS: The adaptive DRIs for Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus decreased, while both adaptive and fixed DRIs for Acinetobacter spp. increased from 2008 to 2013. The adaptive DRIs for Escherichia coli increased from 2008 to 2013, while the fixed DRIs exhibited a decreasing trend. CONCLUSION: DRI could be used to demonstrate the changes of antimicrobial resistance and prescribing over time as a result of evolutionary processes and governmental regulatory interference.

The microbiology of diabetic foot infections in patients recently treated with antibiotic therapy: A prospective study from India.

AIM: Clinicians often treat clinically infected diabetic foot ulcers without information from cultures of the wound. The results of wound cultures may also be affected by previous antibiotic therapy. Thus, we aimed to study the microbial isolates, and antimicrobial sensitivity of previously treated patients with a clinically infected DFU. RESEARCH DESIGN AND METHODS: 293 consecutive patients with clinically infected DFU on prior antimicrobial treatment within the immediate past few days for a duration greater than one week were evaluated for microbial etiology, antibiotic sensitivity and final outcomes. Appropriate tissue samples i.e. purulent drainage, soft-tissue and/ or bone were obtained for aerobic/anaerobic cultures and antimicrobial sensitivities. 71 patients with missing prior antibiotic data were excluded. RESULTS: 313 tissue samples obtained from 222 patients isolated 317 causative organisms. Most of the culture results from tissue specimens were mono-microbial (93.2%) compared to 37% in our previous cohort of 60 patients. Pseudomonas aeruginosa was the most common organism isolated on culture of bone (26.9%) or soft tissue (23.2%) specimen, respectively. Only 23% and 64% of P. aeruginosa isolates and 5.6% and 44% of Acinetobacter sp. were sensitive to quinolones and cephalosporins, respectively. CONCLUSIONS: Clinically infected DFU recently treated with antibiotics have predominant monomicrobial and multi drug-resistant infection. Quinolones as an empirical antibiotic choice may not be appropriate in this setting.

Informing Antibiotic Treatment Decisions: Evaluating Rapid Molecular Diagnostics To Identify Susceptibility and Resistance to Carbapenems against Acinetobacter spp. in PRIMERS III.

The widespread dissemination of carbapenem-resistant Acinetobacter spp. has created significant therapeutic challenges. At present, rapid molecular diagnostics (RMDs) that can identify this phenotype are not commercially available. Two RMD platforms, PCR combined with electrospray ionization mass spectrometry (PCR/ESI-MS) and molecular beacons (MB), for detecting genes conferring resistance/susceptibility to carbapenems in Acinetobacter spp. were evaluated. An archived collection of 200 clinical Acinetobacter sp. isolates was tested. Predictive values for susceptibility and resistance were estimated as a function of susceptibility prevalence and were based on the absence or presence of beta-lactamase (bla) NDM, VIM, IMP, KPC, and OXA carbapenemase genes (e.g., blaOXA-23, blaOXA-24/40, and blaOXA-58 found in this study) against the reference standard of MIC determinations. According to the interpretation of MICs, 49% (n = 98) of the isolates were carbapenem resistant (as defined by either resistance or intermediate resistance to imipenem). The susceptibility sensitivities (95% confidence interval [CI]) for imipenem were 82% (74%, 89%) and 92% (85%, 97%) for PCR/ESI-MS and MB, respectively. Resistance sensitivities (95% CI) for imipenem were 95% (88%, 98%) and 88% (80%, 94%) for PCR/ESI-MS and MB, respectively. PRIMERS III establishes that RMDs can discriminate between carbapenem resistance and susceptibility in Acinetobacter spp. In the context of a known prevalence of resistance, SPVs and RPVs can inform clinicians regarding the best choice for empiric antimicrobial therapy against this multidrug-resistant pathogen.