Beta-lactamase Inhibitor Combinations Research Articles

Impact of an antimicrobial stewardship program indicator on the appropriateness of the empiric antibiotic treatment of urinary source Escherichia coli bacteraemia

A prospective multicentre study was carried out between 2017 and 2021 to assess (1) the appropriateness of the empirical treatment to the local guidelines of urinary source Escherichia coli bacteraemia, (2) the appropriateness of empirical treatment to antibiotic sensitivity results and (3) the degree of error in the local guidelines regarding the antibiotic sensitivity reported in acute care hospitals enrolled in the vigilància de les infeccions relacionades amb l'atenció sanitària de Catalunya program. During the study period, 79.0% of the empirical treatments analysed complied with the guidelines and 88.1% were appropriate in view of the in vitro activity of the isolated strain. The rate of appropriateness rose from 73.8% in 2017 to 81.0% in 2021 (P < 0.001). The degree of error in the recommendations regarding the in vitro activity of the isolated strains was 5.9% and remained stable during the study period. Antibiotic families correctly prescribed according to the guidelines were third-generation cephalosporins (54.9%), carbapenems (16.8%) and combinations of penicillins and beta-lactamase inhibitors (16.4%). Of the 8009 E. coli strains, 19.0% were extended-spectrum beta-lactamases producers, 36.8% were resistant to quinolones and 0.5% were resistant to carbapenems. The broad implementation of an antimicrobial stewardship program with quality indicators of antibiotic use improved compliance to local guidelines in the empiric treatment of urinary tract E. coli bacteraemia. The degree of error in local guidelines was low but higher in more complex hospitals and in healthcare-associated infections. Guidelines need to be constantly updated with the use of epidemiological data, rapid diagnostic tests and the analysis of patient risk factors specific to each geographical area.

Activity of aztreonam-avibactam against Enterobacterales resistant to recently approved beta-lactamase inhibitor combinations collected in Europe, Latin America, and the Asia-Pacific Region (2020–2022)

BackgroundAztreonam-avibactam is under clinical development for treatment of infections caused by carbapenem-resistant Enterobacterales (CRE), especially those resistant to recently approved β-lactamase inhibitor combinations (BLICs). ObjectivesTo evaluate a large collection of CRE isolates, including those non-susceptible to ceftazidime-avibactam, meropenem-vaborbactam, and/or imipenem-relebactam. MethodsOverall, 24 580 Enterobacterales isolates were consecutively collected (1/patient) in 2020–2022 from 64 medical centres located in Western Europe (W-EU), Eastern Europe (E-EU), Latin America (LATAM), and the Asia-Pacific region (APAC). Of those, 1016 (4.1%) were CRE. Isolates were susceptibility tested by broth microdilution. CRE isolates were screened for carbapenemase genes by whole genome sequencing. ResultsAztreonam-avibactam inhibited 99.6% of CREs at ≤8 mg/L. Ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-relebactam were active against 64.6%, 57.4%, and 50.7% of CRE isolates, respectively; most of the non-susceptible isolates carried metallo-beta-lactamases. Aztreonam-avibactam was active against ≥98.9% of isolates non-susceptible to these BLICs. The activity of these BLICs varied by region, with highest susceptibility rates observed in W-EU (76.9% for ceftazidime-avibactam, 72.5% for meropenem-vaborbactam, 63.8% for imipenem-relebactam) and the lowest susceptibility rates identified in the APAC region (39.9% for ceftazidime-avibactam, 37.8% for meropenem-vaborbactam, and 27.5% for imipenem-relebactam). The most common carbapenemase types overall were KPC (44.6% of CREs), NDM (29.9%), and OXA-48–like (16.0%). KPC predominated in LATAM (64.1% of CREs in the region) and W-EU (61.1%). MBL occurrence was highest in APAC (59.5% of CREs in the region), followed by LATAM (34.0%), E-EU (28.9%), and W-EU (23.6%). ConclusionsAztreonam-avibactam demonstrated potent activity against CRE isolates resistant to ceftazidime-avibactam, meropenem-vaborbactam, and/or imipenem-relebactam independent of the carbapenemase produced.

Inoculum effect of CTX-M-15, OXA-48, and KPC-2 producing Klebsiella pneumoniae on meropenem and ceftazidime-avibactam efficacy.

The inoculum effect, characterized by diminished antibacterial activity at high bacterial inocula, is studied in the context of beta-lactam and beta-lactamase inhibitor combinations against beta-lactamase-producing Enterobacterales. The inhibition of ESBL + OXA-48 and KPC enzymes, in combination with ceftazidime, demonstrates encouraging results. In this study, 20 Klebsiella pneumoniae isolates were tested with different inocula (1-5 × 105 and 1-5 × 107cfu/ml) using broth microdilution methods. The inoculum effect was observed in meropenem against OXA-48 + CTX-M-15- and KPC-2-producing isolates but not with ceftazidime/avibactam. Notably, meropenem exhibited inoculum effect against carbapenemase-producing strains, whereas ceftazidime-avibactam remained effective. We conclude that ceftazidime-avibactam is recommended for high-inoculum infections.

Emerging Coproduction of AmpC Beta-lactamase in Extended-spectrum Beta-lactamase-producing Escherichia coli Clinical Isolates in Indonesia

ABSTRACT Introduction: Extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase (AmpC-BL) in Enterobacteriaceae are a global threat. Coproduction of AmpC-BL and ESBL reduces therapeutic options, with more resistance against cephamycin and beta-lactamase inhibitor combinations. This study determines the proportion, incidence, and distribution of AmpC-BL-resistant genes in clinically isolated ESBL-producing Escherichia coli, completing its scarce data in Indonesia. Methods: The samples in this study were ESBL-producing E. coli from blood and urine specimens, confirmed by BD Phoenix semiautomatic examination combined with cefoxitin disk screening method. Confirmation tests of AmpC-BL used the AmpC-disk method and the polymerase chain reaction method. Results: Thirteen (27.8%) of 108 E. coli isolates were nonsusceptible to cefoxitin, and 3 (11.5%) isolates were confirmed to produce AmpC-BL and contained AmpC-BL CITM gene. Of the 3 AmpC-BL and ESBL coproduction isolates, one isolate was a copresentation of ESBL and AmpC-BL genes, namely blaTEM and CITM. Fisher’s exact test showed that the coproduction of AmpC-BL in ESBL-producing isolates was associated with reduced susceptibility to cefoxitin (P = 0.020) and amoxicillin-clavulanate (P = 0.048) compared to isolates producing ESBL alone. The effect of ESBL and AmpC-BL coproduction on reducing susceptibility to carbapenems needs further investigation. Conclusions: AmpC coproduction was found in 3 (2.8%) of 108 ESBL-producing E. coli isolates, and one isolate copresented AmpC-BL and ESBL coding genes blaTEM and CITM. These three isolates were associated with widened antibiotic resistance to cefoxitin and amoxicillin--clavulanate compared to isolates producing ESBL alone.

1949. Activity of Aztreonam-Avibactam against Enterobacterales Resistant to Recently Approved Beta-Lactamase Inhibitor Combinations Collected Worldwide (ex-US; 2020–2022)

Abstract Background Aztreonam-avibactam (ATM-AVI) is under clinical development. Aztreonam is a monobactam stable to hydrolysis by metallo-β-lactamases (MBLs). ATM-AVI has shown activity against MBL-producing, carbapenem-resistant Enterobacterales (CRE) that are resistant to recently approved β-lactamase inhibitor combinations (BLIs) such as ceftazidime-avibactam (CAZ-AVI), meropenem-vaborbactam (MEM-VAB), and imipenem-relebactam (IMI-REL). We evaluated a large collection of CRE isolates nonsusceptible (NS) to these BLIs. Methods 24,580 Enterobacterales isolates were consecutively collected (1/patient) in 2020–2022 from 64 medical centers located in Western Europe (W-EU; 27 centers in 10 countries), Eastern Europe (E-EU; 13 centers in 9 countries), Latin America (LATMA; 8 centers in 6 countries), and the Asia-Pacific region (APAC; 16 centers in 8 countries). Among these isolates, 1,016 (4.1%) were CRE. Isolates were susceptibility tested by CLSI broth microdilution. CRE isolates were screened for carbapenemase (CPE) genes by whole genome sequencing. Results ATM-AVI inhibited 99.6% of CREs (MIC50/90, 0.25/0.5 mg/L) and ≥ 98.9% of CRE isolates NS to CAZ-AVI, MEM-VAB, and/or IMI-REL at ≤8 mg/L (Table). The most active comparators against CREs were CAZ-AVI (64.6%S), MEM-VAB (57.4%S), and IMI-REL (50.7%S). The activity of these BLIs varied widely among region, with highest susceptibility rates observed in W-EU (76.9% for CAZ-AVI, 72.5% for MEM-VAB, 63.8% for IMI-REL), followed by LATAM (65.1% for CAZ-AVI, 70.6% for MEM-VAB, 62.8% for IMI-REL), E-EU (66.6% for CAZ-AVI, 46.7% for MEM-VAB, 43.5% for IMI-REL), and APAC (39.9% for CAZ-AVI, 37.8% for MEM-VAB, 27.7% for IMI-REL). The most common CPE types overall were KPC (44.5% of CREs), NDM (29.8%), and OXA-48-like (16.0%). KPC predominated in LATAM (64.1%) and W-EU (61.1% of CREs). MBL occurrence was highest in APAC (59.5% of CREs), followed by LATAM (34.0%), E-EU (28.9%), and W-EU (23.6%). NDM represented 85.4% of MBLs. Conclusion ATM-AVI demonstrated potent activity against CRE isolates resistant to CAZ-AVI, MEM-VAB, and/or IMI-REL independent of the CPE produced. The activity of recently approved BLIs varied broadly among regions and were very limited in E-EU and APAC. Disclosures Helio S. Sader, MD, PhD, FIDSA, AbbVie: Grant/Research Support|Basilea: Grant/Research Support|Cipla: Grant/Research Support|Paratek: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support Mariana Castanheira, PhD, AbbVie: Grant/Research Support|Basilea: Grant/Research Support|bioMerieux: Grant/Research Support|Cipla: Grant/Research Support|CorMedix: Grant/Research Support|Entasis: Grant/Research Support|Melinta: Grant/Research Support|Paratek: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support Leonard R. Duncan, PhD, AbbVie: Grant/Research Support|Basilea: Grant/Research Support|CorMedix: Grant/Research Support|Melinta: Grant/Research Support|Pfizer: Grant/Research Support John H. Kimbrough, PhD, AbbVie: Grant/Research Support|Basilea: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support Cecilia G. Carvalhaes, MD, PhD, AbbVie: Grant/Research Support|bioMerieux: Grant/Research Support|Cipla: Grant/Research Support|CorMedix: Grant/Research Support|Melinta: Grant/Research Support|Pfizer: Grant/Research Support Rodrigo E. Mendes, PhD, AbbVie: Grant/Research Support|Basilea: Grant/Research Support|Cipla: Grant/Research Support|Entasis: Grant/Research Support|GSK: Grant/Research Support|Paratek: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support

Molecular characterization of IncFII plasmid carrying blaNDM-5 in a Salmonella enterica serovar Typhimurium ST34 clinical isolate in China.

In this study, an IncFII plasmid pIncFII-NDM5 carrying blaNDM-5 was found in carbapenem-resistant Salmonella enterica serovar Typhimurium (S. enterica serovar Typhimurium), which has conjugative transferability and carried blaNDM-5, bleMBL, mph(A), and blaTEM-1 four resistance genes that can mediate resistance to multiple antibiotics including cephalosporins, beta-lactamase inhibitor combinations, carbapenems, and macrolides. Phylogenetic analysis showed that 1104-65 and 1104-75 were closely related to other S. enterica serovar Typhimurium in this area. The above-mentioned S. enterica serovar Typhimurium chromosome carries blaCTX-M-55, qnrS1, and tet(A) genes, so the antibiotic resistance of isolates will be further enhanced after obtaining the pIncFII_NDM5-like plasmid. Meanwhile, we discovered a novel genetic structure of blaNDM-5 mediated by the IS26 composite transposon, which will expand our understanding of the emergence and spread of carbapenem-resistance genes. Altogether, the presence of the IncFII plasmid pIncFII-NDM5 further underscores the need for vigilant surveillance and appropriate infection control measures to mitigate the impact of carbapenem-resistant S. enterica serovar Typhimurium in clinical settings.

Incidence of Ventilator-Associated Pneumonia and its Bacterial Characterization – Intervention Based Prospective Study

Objectives: Ventilator-associated pneumonia (VAP) is a widely recognized and potentially fatal healthcare-related infection that occurs in all high-dependency units. Mechanically ventilated patients are at an elevated risk of developing VAP, which has a high death and morbidity rate. The prevalence of VAP varies greatly depending on the location and diagnostic approach. Radiological and clinical markers impact VAP diagnosis accuracy. Reliable sampling and confirmation of microbes are highly recommended. The purpose of this study was to document the incidence, patient distribution, bacteriological profile, and antibiotic susceptibility pattern of VAP patients. Material and Methods: A prospective observational study was done between January 2016 and December 2019. Critically, ill patients on mechanical ventilation for more than 48 hours were included in the study. Based on the initial baseline, positive end-expiratory pressure, and fraction of inspired oxygen were followed by three-tier VAP criteria as per NSHN guidelines. Results: Out of 1220 VAP-suspected patients (mechanically ventilated), 49 patients developed hospital-acquired VAP. The incidence of VAP significantly reduced from 10.7 to 1.4 VAP/1000 ventilator days with continuous intervention and auditing over some time. Elderly males aged 51–66 years were found to be in higher risk groups. Klebsiella pneumoniae and Pseudomonas aeruginosa were found to be the most common pathogen. The majority of Enterobacterales (79%) were found to be resistant to third-generation cephalosporin, 69% were resistant toward fluoroquinolone and cotrimoxazole, followed by 55% resistance to beta-lactam and beta-lactamase inhibitor combination. Conclusion: Targeted strategies with implementable policies, such as the care bundle approach, will reduce the in-patient days. It might improve patient outcomes and reduce the incidence of VAP.

Lymphadenopathies associated with Cat-Scratch Disease in Turkiye

Aim: Bartonella henselae is the etiologic agent of cat-scratch disease. The disease affects children and young adults. The objective of this study is to analyze the epidemiology, clinical features, and course of this disease in Turkiye. &#x0D; Materials and Methods: Children without immunodeficiency, with relevant clinical signs and symptoms, and positive serology were included in the study. Clinical, demographic and laboratory data of patients diagnosed with cat-scratch disease between October 2018 and February 2021 were evaluated retrospectively.&#x0D; Results: A total of 46 patients were included. The mean age was 132 months (IQR 90- 153 months), and 69.6% (n = 32) were male. There was a history of cat contact in 73.9% of the patients and 43.5% of these were with household cats. Most of the lymphadenopathies were axillary (73.9%), and generalized lymphadenopathy was not observed. The median duration of symptoms before admission was 4 weeks. The median ultrasonographic lymphadenopathy size was 4 cm. The median clinical improvement time was 6.5 weeks. Azithromycin was given in 18 patients and intravenous and/or oral beta-lactamase inhibitor combination therapy in 18 patients while no treatment was necessary in 10 patients.&#x0D; Conclusion: The typical presentation is a solitary, enlarged lymph node, mostly in the axillary region. Bartonella henselae IgG level should be studied prior to invasive procedures. It should be known that cat scratch disease can develop without a history of cat contact. Meanwhile, it should be known that contact with a house cat may cause disease more often than contact with street cats.

Prescribing Pattern of Antibiotics among Hospitalized Patients with Urinary Tract Infection.

Urinary tract infection is one of the most common bacterial infections worldwide. It has become one of the most common cause for the hospitalization and sepsis. It is generally treated with antimicrobial agents and fluids. This study was conducted to study the prescribing pattern of antibiotic among hospitalized patients with urinary tract infection. A descriptive cross-sectional study was conducted in Nepal Medical College Teaching Hospital, Attarkhel, Kathmandu from January 2022 to April 2022. Patients aged 18 years or above of both sex, admitted to various departments with the provisional diagnosis of urinary tract infection prescribed with antibiotics were included in the study. Out of 146 patients admitted with a diagnosis of urinary tract infection, the most commonly prescribed antibiotics during hospital stay were cephalosporin in 102 (69.9%) patients followed by combination of penicillin and beta-lactamase inhibitors (31, 21.2%) and fluoroquinolones (15, 10.3%). Ceftriaxone (78, 53.4%) alone was the most commonly prescribed antibiotic as empirical therapy followed by combination of piperacillin and tazobactam (22, 15.1%). One hundred and forty four (78.6%) patients were prescribed antibiotics from the watch group followed by the access group (21, 11.5 %). E. coli was the most common organism isolated in 29 (76.3%) patients. Cephalosporin was the commonest antibiotic group prescribed in hospitalized patients among which ceftriaxone was commonly prescribed as an empirical therapy. Among AWaRe classification, antibiotics from the watch group were commonly prescribed.

The Prevalence of Multidrug-Resistant Enterobacteriaceae among Neonates in Kuwait.

Increasing numbers of neonates with serious bacterial infections, due to resistant bacteria, are associated with considerable morbidity and mortality rates. The aim of this study was to evaluate the prevalence of drug-resistant Enterobacteriaceae in the neonatal population and their mothers in Farwaniya Hospital in Kuwait and to determine the basis of resistance. Rectal screening swabs were taken from 242 mothers and 242 neonates in labor rooms and wards. Identification and sensitivity testing were performed using the VITEK® 2 system. Each isolate flagged with any resistance was subjected to the E-test susceptibility method. The detection of resistance genes was performed by PCR, and the Sanger sequencing method was used to identify mutations. Among 168 samples tested by the E-test method, no MDR Enterobacteriaceae were detected among the neonates, while 12 (13.6%) isolates from the mothers' samples were MDR. ESBL, aminoglycosides, fluoroquinolones, and folate pathway inhibitor resistance genes were detected, while beta-lactam-beta-lactamase inhibitor combinations, carbapenems, and tigecycline resistance genes were not. Our results showed that the prevalence of antibiotic resistance in Enterobacteriaceae obtained from neonates in Kuwait is low, and this is encouraging. Furthermore, it is possible to conclude that neonates are acquiring resistance mostly from the environment and after birth but not from their mothers.

Effect of ICU quality control indicators on VAP incidence rate and mortality: a retrospective study of 1267 hospitals in China

PurposeTo investigate the effects of ICU quality control indicators on the VAP incidence rate and mortality in China throughout 2019.MethodsThis was a retrospective study. A total of 1267 ICUs from 30 provinces in mainland China were included. Data were collected using the National Clinical Improvement System Data that report ICU information. Ten related quality control indicators were analyzed, including 5 structural factors (patient-to-bed ratio, physician-to-bed ratio, nurse-to-bed ratio, patient-to-physician ratio, and patient-to-nurse ratio), 3 process factors (unplanned endotracheal extubation rate, reintubation rate within 48 h, and microbiology detection rate before antibiotic use), and 2 outcome factors (VAP incidence rate and mortality). The information on the most common infectious pathogens and the most commonly used antibiotics in ICU was also collected. The Poisson regression model was used to identify the impact of factors on the incidence rate and mortality of VAP.ResultsThe incidence rate of VAP in these hospitals in 2019 was 5.03 (2.38, 10.25) per 1000 ventilator days, and the mortality of VAP was 11.11 (0.32, 26.00) %. The most common causative pathogen was Acinetobacter baumannii (in 39.98% of hospitals), followed by Klebsiella pneumoniae (38.26%), Pseudomonas aeruginosa, and Escherichia coli. In 26.90% of hospitals, third-generation cephalosporin was the most used antibiotic, followed by carbapenem (24.22%), penicillin and beta-lactamase inhibitor combination (20.09%), cephalosporin with beta-lactamase inhibitor (17.93%). All the structural factors were significantly associated with VAP incidence rate, but not with the mortality, although the trend was inconsistent. Process factors including unplanned endotracheal extubation rate, reintubation rate in 48 h, and microbiology detection rate before antibiotic use were associated with higher VAP mortality, while unplanned endotracheal extubation rate and reintubation rate in 48 h were associated with higher VAP mortality. Furthermore, K. pneumoniae as the most common pathogen was associated with higher VAP mortality, and carbapenems as the most used antibiotics were associated with lower VAP mortality.ConclusionThis study highlights the association between the ICU quality control (QC) factors and VAP incidence rate and mortality. The process factors rather than the structural factors need to be further improved for the QC of VAP in the ICU.

1693. Meropenem-Xeruborbactam: In Vitro Potency against Gram-Negative Bacteria in Comparison with Marketed and Investigational Beta-lactam (BL)/Beta-lactamase Inhibitor (BLI) Combinations

Abstract Background Several BLI combinations have entered into clinical testing or been approved for use but there are few comparative studies of their in vitro activity. Xeruborbactam (XER, formerly QPX7728) is a cyclic boronate BLI with potent inhibitory activity against serine and metallo-beta-lactamases (MBL). It is in clinical development in combination with meropenem (MEM). The objective of this study was to compare in vitro potency of MEM-XER to that of other investigational and approved BL/BLI combinations in head-to-head testing against recent isolates of carbapenem-resistant Enterobacterales (CRE) and Acinetobacter baumannii (CRAB) as well as Pseudomonas aeruginosa (PA). Methods The test panel of recent worldwide isolates consisted of 507 CRE including 168 MBL producers (157 NDM, 11 VIM, 1 IMP), 506 CRAB, and 506 PA that were representative of current isolates and included 65 MDR (resistant to ≥ 3 antimicrobial classes) strains. MEM-XER was tested with XER at a fixed 8 mg/L conc. and other BL/BLI combinations at their recommended BLI concentrations. MIC testing was conducted blinded to drug identity using CLSI reference methods and controlled using approved quality control bacterial strains and ranges. Results The MIC50 and MIC90 for MEM-XER vs CRE ranged from ≤ 0.03 mg/L to 0.06 mg/L and 0.06 mg/L to 1 mg/L, respectively. MEM-XER and cefepime-taniborbactam (FEP-TANI) were the only BL/BLIs with activity against MBL-producers; based on MIC90, MEM-XER (MIC90 of 1 mg/L) was 16-fold more potent than FEP-TANI (MIC90 of 16 mg/L). MEM-XER and sulbactam-durlobactam (SUL-DUR) were the only agents with high potency against CRAB, with MIC50/MIC90 of 0.5/4 mg/L and 1/2 mg/L. For the representative panel of PA, the potency of MEM-XER, FEP-TAN, ceftolozane-tazobactam (TOL-TAZ), imipenem-relebactam (IMP-REL), and CAZ-AVI was similar with MIC90s ranging between 2-8 mg/L; for the MDR panel, MIC90‘s were &amp;gt; 8 mg/L for all combinations, with MER-XER, IMP-REL, TOL-TAZ, and CAZ-AVI having MIC50’s of 2-4 mg/L. Conclusion Compared to the marketed or investigational BL/BLIs, MEM-XERU had the broadest coverage of carbapenem-resistant gram-negative bacteria, with the most differentiating property being activity against multiple strains of MBL-producing CRE and CRAB. Disclosures Mariana Castanheira, PhD, AbbVie: Grant/Research Support|Cidara: Grant/Research Support|GSK: Grant/Research Support|Melinta: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support Jill Lindley, BS, AbbVie: Grant/Research Support.

In Vitro Efficacy of Tetracyclines Against Multi Drug Resistant Acinetobacter Baumannii Amongst Intensive Care Patients

Objective: To determine the anti-microbial susceptibility and frequency of A.baumannii, especially focusing the efficacy of Doxycycline and Minocycline against multi drug resistant (MDR) and extremely drug resist ant (XDR) A.baumannii in atertiary care hospital.&#x0D; Study Design: It was a descriptive cross sectional study.&#x0D; Place and Duration of Study: Study conducted at the department of Pathology, Armed Forces Institute of Cardiology/National Institute of Heart Diseases (AFIC/NIHD), Rawalpindi Pakistan from Jan 2020 to Dec 2021.&#x0D; Methodology: It was a descriptive cross sectional study conducted at the department of Pathology Armed Forces Institute of Cardiology (AFIC) and National Institute of Heart Diseases, Rawalpindi (NIHD) from Jan 2020 to Dec 2021. Data was collected by non-probability consecutive sampling. Antimicrobial susceptibility was assessed for A.baumanni isolated from hospital setting.&#x0D; Results: 6239 culture specimens were received from different wards of AFIC. Out of these 1439 (23 %) yielded growth of different pathogens. Amongst 1439 positive cultures, 167 (11.6 %) were A.baumannii. Multi drug resistant (MDR) A.baumannii were 9(5.4%), extremely drug resistant (XDR) 152(91%) and pan drug resistant (PDR) were 6(3.6%). Antibiotic susceptibility of A. baumannii revealed highest resistance for cephalosporins and carbapenems about 162(97%), ampicillin and beta lactamase inhibitor combinations about 157(94%), quinolones 152(91%), aminoglycosides 134(80%) and Trimethoprim+sulfamethoxazole 131(78%). The least resistance observed from tetracyclines group of antibiotics which was 34(20%) from Minocycline and 54(32%) from Doxycycline.&#x0D; Conclusion: A high resistant pattern was observed for A.baumanni against cephalosporins, carbapenems, ampicillin, beta lactamase inhibitor combinations, quinolones, aminoglycosides and Trimethoprim+sulfamethoxazole. Comparatively tetracycline antimicrobials i.e. minocycline and doxycycline were found to be less resistant than others to manage MDR and XDR cases.

In Vitro Susceptibility of Colistin Against Multidrug Resistant Klebsiella Pneumoniae Clinical Isolates

Objectives: To determine in-vitro efficacy of colistin against resistant Klebsiella Pneumoniae clinical isolates. &#x0D; Study Design: Cross-sectional study.&#x0D; Place and Duration of Study: Microbiology Department of Pathology Lab, Armed Forces Institute of Cardiology &amp; National Institute of Heart Diseases, Rawalpindi, Pakistan, from Jan 2021 to Dec 2021.&#x0D; Methodology: This cross-sectional study was carried out at the microbiology department of pathology lab, Armed Forces institute of Cardiology &amp; National Institute of Heart Diseases, Rawalpindi through Jan 2021 to Dec 2021. Sampling was done by nonprobability consecutive technique. Antimicrobial susceptibility testing was done for all clinical isolates of KP.&#x0D; Results: A total of 3066 culture and sensitivity requests were received, out of these 663(21.6%) specimens revealed growth of different microorganisms. Amongst 663 culture positive isolates, 150(22.6 %) were identified as KP. Antibiotic susceptibility of KP showed &gt;90% isolates resistant to 3rd &amp; 4th generation cephalosporins, cotrimoxazole, ampicillin+salbactum and coamoxiclav. Aminoglycosides, quinolones, meropenem, aztreonam and tazobactum+pipracillin were found resistant in &gt;80% isolates and doxycycline and imipenem in &gt;70% isolates. Resistance to minocycline was 58%, chloramphenicol 40.7% and Tigecycline 38.7%. The least resistance was noted in Colistin 16%.&#x0D; Conclusion: A very high antimicrobial resistance was observed in KP isolates against penicillins, cephalosporins, ampicillin beta lactamase inhibitor combinations, quinolones, aminoglycosides, carbapenems and cotrimoxazole. Comparatively tigecyclines and chloramphenicol were found to be less resistant than other antimicrobials to manage MDR and XDR cases. Colistin has excellent efficacy against MDR and XDR KP isolates.

Hypermutator strains of Pseudomonas aeruginosa reveal novel pathways of resistance to combinations of cephalosporin antibiotics and beta-lactamase inhibitors.

Hypermutation due to DNA mismatch repair (MMR) deficiencies can accelerate the development of antibiotic resistance in Pseudomonas aeruginosa. Whether hypermutators generate resistance through predominantly similar molecular mechanisms to wild-type (WT) strains is not fully understood. Here, we show that MMR-deficient P. aeruginosa can evolve resistance to important broad-spectrum cephalosporin/beta-lactamase inhibitor combination antibiotics through novel mechanisms not commonly observed in WT lineages. Using whole-genome sequencing (WGS) and transcriptional profiling of isolates that underwent in vitro adaptation to ceftazidime/avibactam (CZA), we characterized the detailed sequence of mutational and transcriptional changes underlying the development of resistance. Surprisingly, MMR-deficient lineages rapidly developed high-level resistance (>256 μg/mL) largely without corresponding fixed mutations or transcriptional changes in well-established resistance genes. Further investigation revealed that these isolates had paradoxically generated an early inactivating mutation in the mexB gene of the MexAB-OprM efflux pump, a primary mediator of CZA resistance in P. aeruginosa, potentially driving an evolutionary search for alternative resistance mechanisms. In addition to alterations in a number of genes not known to be associated with resistance, 2 mutations were observed in the operon encoding the RND efflux pump MexVW. These mutations resulted in a 4- to 6-fold increase in resistance to ceftazidime, CZA, cefepime, and ceftolozane-tazobactam when engineered into a WT strain, demonstrating a potentially important and previously unappreciated mechanism of resistance to these antibiotics in P. aeruginosa. Our results suggest that MMR-deficient isolates may rapidly evolve novel resistance mechanisms, sometimes with complex dynamics that reflect gene inactivation that occurs with hypermutation. The apparent ease with which hypermutators may switch to alternative resistance mechanisms for which antibiotics have not been developed may carry important clinical implications.

Factors Associated with Gram-Negative Bacteremia and Mortality in Neutropenic Patients with Hematologic Malignancies in a High-Resistance Setting.

Patients with hematological malignancies (HMs) have a substantial incidence of febrile neutropenic episodes. Gram-negative bacteremia (GNB) is still the major cause of these episodes. We evaluated the factors associated with GNB and mortality of bacteremic patients with HMs in a high-resistance setting. We conducted a prospective cohort study from March 2018 to June 2019 with 66 bacteremic and 132 non-bacteremic patients. Regression analyses were used to identify factors associated with GNB and 30-day mortality. The mean age was 53.83±15.21 years, and 129 (65.2%) of the patients were male. In multivariable analysis, factors independently associated with GNB were male gender, duration of hospitalization and neutropenia before the febrile neutropenic episode, leukemias and allogeneic transplant recipients, radiotherapy, receiving glucocorticosteroids, colonization with resistant microorganisms. All-cause mortality and 30-day mortality were 47.0% and 30.3% in cases of GNB, compared to non-bacteremic controls 25.0% and 10.6%, respectively. Sepsis, duration of hospitalization before the febrile neutropenic episode, carbapenem-resistant GNB, and inappropriate empirical antibiotic treatment was found as factors associated with 30-day mortality. Prior antibiotic exposure particularly beta-lactamase inhibitor combinations and carbapenems during the past 30 days was more frequent in the bacteremic group. An increasing trend was observed in multidrug-resistant (MDR) bacteria (p=0.03) and carbapenem-resistant Enterobacterales (p=0.02) over the years. By considering the risk factors associated with GNB and 30-day mortality that we detected in our study among neutropenic patients, a personalized approach for the management of febrile neutropenic patients can be designed by means of an effective antimicrobial stewardship program including the appropriate use of broad-spectrum antibiotics.

Characterization, genome analysis and in vitro activity of a novel phage vB_EcoA_RDN8.1 active against multi-drug resistant and extensively drug-resistant biofilm-forming uropathogenic Escherichia coli isolates, India.

We aimed to study host range, stability, genome and antibiofilm activity of a novel phage vB_EcoA_RDN8.1 active against multi-drug resistant (MDR) and extensively drug-resistant (XDR) biofilm-forming uropathogenic Escherichia coli isolates. A novel lytic phage vB_EcoA_RDN8.1 active against UPEC strains resistant to third-generation cephalosporins, fluoroquinolones, aminoglycosides, imipenem, beta-lactamase inhibitor combination and polymyxins was isolated from community raw sewage water of Chandigarh. It exhibited a clear plaque morphology and a burst size of 250. In the time-kill assay, the maximum amount of killing was achieved at MOI 1.0. vB_EcoA_RDN8.1 belongs to the family Autographiviridae, has a genome size of 39.5kb with a GC content of 51.6%. It was stable over a wide range of temperatures and pH. It was able to inhibit biofilm formation which may be related to an endolysin encoded by ORF 19. The vB_EcoA_RDN8.1 is a novel lytic phage that has the potential for inclusion into phage cocktails being developed for the treatment of urinary tract infections (UTIs) caused by highly drug-resistant UPEC. We provide a detailed characterization of a novel lytic Escherichia phage with antibiofilm activity having a potential application against MDR and XDR UPEC causing UTIs.

Clinical Outcome of Discordant Empirical Therapy and Risk Factors Associated to Treatment Failure in Children Hospitalized for Urinary Tract Infections.

With the spread of antibiotic resistance in pediatric urinary tract infections (UTIs), more patients are likely to be started empirically on antibiotics to which pathogens are later found to be resistant (discordant therapy). However, in-vivo effectiveness may be different from in-vitro susceptibility. Aims of this study were to describe clinical outcomes of discordant empirical treatments in pediatric UTIs and to investigate risk factors associated to treatment failure. This observational, retrospective study was conducted on children hospitalized for febrile UTIs with positive urine culture and started on discordant empirical therapy. Failure rates of discordant treatments and associated risk factors were investigated. A total of 142/1600 (8.9%) patients were treated with inadequate empirical antibiotics. Clinical failure was observed in 67/142 (47.2%) patients, with no fatal events. Higher failure rates were observed for combinations of penicillin and beta-lactamase inhibitors (57.1%). Significant risk factors for failure of discordant treatment were history of recurrent UTIs (95% CI: 1.13–9.98, OR: 3.23, p < 0.05), recent use of antibiotics (95% CI: 1.46–21.82, OR: 5.02, p < 0.01), infections caused by Pseudomonas aeruginosa (95% CI: 1.85–62.10, OR: 7.30, p < 0.05), and empirical treatment with combinations of penicillin and beta-lactamase inhibitors (95% CI: 0.94–4.03, OR: 1.94, p = 0.05). This study showed that discordant empirical treatments may still be effective in more than half of pediatric UTIs. Clinical effectiveness varies between different discordant antibiotics in pediatric UTIs, and patients presenting risk factors for treatment failure may need a differentiated empirical approach.

Pharmacokinetic and pharmacodynamic analysis of cefoperazone/sulbactam for the treatment of pediatric sepsis by Monte Carlo simulation.

Pediatric sepsis syndrome is one of the most common reasons for pediatric intensive care unit hospitalization (PICU). Cefoperazone/sulbactam is a time-dependent beta-lactamase inhibitor combination which has been widely used in the treatment of sepsis. But the pharmacokinetic (PK) and pharmacodynamic (PD) data of cefoperazone/sulbactam are unknown in children with sepsis. The present work aimed to determine whether the usual dosing regimens of cefoperazone/sulbactam (1 hour infusion, 50 mg kg-1, every 12 hours) were suitable for these patients in PICU. A total of fourteen patients were enrolled and the PK parameters were estimated by non-compartmental analysis using WinNonlin software. The t1/2 and AUC0-12 of cefoperazone and sulbactam were 3.60 and 1.77 h, and 900.97 and 67.68 h μg mL-1, respectively. The Vd and CL of cefoperazone and sulbactam were 1.65 L and 5.16 L, and 17.41 mL min-1 and 122.62 mL min-1, respectively. The probability of target attainments (PTAs) of cefoperazone at different minimum inhibitory concentrations (MICs) based on the percentage time that concentrations exceed the minimum inhibitory concentration (% T > MIC) value were performed by Monte Carlo simulation and PTA was >90% at MICs ≤16 μg mL-1. The PK/PD profile of dosing regimens tested will assist in selecting the appropriate cefoperazone/sulbactam regimens for these patients. At a target of 80% T > MIC, the usual dosing regimens can provide good coverage for pathogens with MICs of ≤32 μg mL-1. The ratio between cefoperazone and sulbactam at 1 : 1 may be more suitable in pediatric sepsis. Individual dose and therapeutic drug monitoring in clinical practice will help achieve the best therapeutic effect while minimizing toxicity.

Influence of Antimicrobial Stewardship and Molecular Rapid Diagnostic Tests on Antimicrobial Prescribing for Extended-Spectrum Beta-Lactamase- and Carbapenemase-Producing Escherichia coli and Klebsiella pneumoniae in Bloodstream Infection.

ABSTRACTThe objective of this study was to evaluate whether the addition of the Verigene BC-GN molecular rapid diagnostic test to standard antimicrobial stewardship practices (mRDT + ASP) decreased the time to optimal and effective antimicrobial therapy for patients with extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections (BSI) compared to conventional microbiological methods with ASP (CONV + ASP). This was a multicenter, retrospective cohort study evaluating the time to optimal antimicrobial therapy in 5 years of patients with E. coli or K. pneumoniae BSI determined to be ESBL- or carbapenemase-producing by mRDT and/or CONV. Of the 378 patients included (mRDT + ASP, n = 164; CONV + ASP, n = 214), 339 received optimal antimicrobial therapy (mRDT + ASP, n = 161; CONV + ASP, n = 178), and 360 (mRDT + ASP, n = 163; CONV + ASP, n = 197) received effective antimicrobial therapy. The mRDT + ASP demonstrated a statistically significant decrease in the time to optimal antimicrobial therapy (20.5 h [interquartile range (IQR), 17.0 to 42.2 h] versus 50.1 h [IQR, 27.6 to 77.9 h]; P < 0.001) and the time to effective antimicrobial therapy (15.9 h [IQR, 1.9 to 25.7 h] versus 28.0 h [IQR, 9.5 to 56.7 h]; P < 0.001) compared to CONV + ASP, respectively.IMPORTANCE Our study supports the additional benefit of molecular rapid diagnostic test in combination with timely antimicrobial stewardship program (ASP) intervention on shortening the time to both optimal and effective antimicrobial therapy in patients with ESBL- or carbapenemase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections, compared to conventional microbiological methods and ASP. Gram-negative infections are associated with significant morbidity and mortality, often resulting in life-threatening organ dysfunction. Both resistance phenotypes confer resistance to many of our first-line antimicrobial agents with carbapenemase-producing Enterobacterales requiring novel beta-lactam and beta-lactamase inhibitor combinations or other susceptible non-beta-lactam antibiotics for treatment. National resistance trends in a cohort of hospitalized patients at U.S. hospitals during our study period demonstrate the increasing incidence of both resistance phenotypes, reinforcing the generalizability and timeliness of such analysis.