Background: H. pylori (Helicobacter pylori) infections typically occur in early childhood. Although the prevalence of H. pylori in children is lower than that in adults, the eradication rate of this infection in children is relatively low because of resistance. In this study, we analyzed personalized treatment strategies to achieve treatment goals based on H. pylori resistance characteristics. This retrospective single-center study was conducted between January 2019 and December 2022 and enrolled 1,587 children who presented with upper gastrointestinal symptoms and underwent endoscopy. H. pylori culturing and antimicrobial susceptibility testing were performed. Results: Culture-positive results for H. pylori were obtained in 535 children. The resistance rates to clarithromycin (CLA), metronidazole (MET), and levofloxacin (LEV) were 39.8%, 78.1%, and 20.2%, respectively. None of the isolates were resistant to tetracycline (TET), amoxicillin (AMO), or furazolidone (FZD). Double resistance rates to CLA + MET, CLA + LEV, and MET + LEV were 19.1%, 3.0%, and 5.8%, respectively. Notably, triple-resistant to CLA + MET + LEV was 9.7%. Based on susceptibility tests, individualized triple therapy [proton pump inhibitor (PPI) +AMO + CLA/MET] was selected for 380 children with H. pylori sensitive to MET and/or CLA. In 155 children resistant to CLA and MET, bismuth-based quadruple therapy was recommended; for unable to receive bismuth, concomitant therapy was recommended for 14 children (<8 years of age); triple therapy with TET was recommended for 141 children (>8 years of age), with 43 children (>14 years of age) requiring FZD rather than TET. Conclusion: Resistance to H. pylori in Chinese children was relatively poor. Personalized therapy regimens should be based on susceptibility tests and avoided factors associated with treatment failure.

Current global variations exist in Helicobacter pylori (H. pylori) eradication regimens. Triple therapy (TT), bismuth quadruple therapy (BQT), and high-dose dual therapy (HDDT) currently represent the predominant regimens. These regimens diverge in terms of treatment duration, the utilization of susceptibility testing, acid-inhibiting drug administration, and patient education. We conducted a comprehensive systematic literature review on these H. pylori treatment regimens. Our review aims to provide standardized treatment recommendations for H. pylori, reducing the risk of amalgamating findings from diverse eradication regimens. Recent research suggests that the optimal treatment duration for TT and BQT may be 14 and 10 days, respectively. Selecting the appropriate treatment duration for HDDT should rely on regional research evidence, and 14 days may be the optimal duration. The incorporation of susceptibility testing in TT is of paramount importance. In the case of BQT, the absence of susceptibility testing may be considered as an option, contingent upon cost and availability, and should be determined based on local antibiotic resistance patterns and the efficacy of empirical regimens. The type and dosage of acid-inhibiting drug would affect the efficacy of these regimens. Acid-inhibiting drugs should be selected and applied reasonably according to the population and therapies. Adequate patient education plays a pivotal role in the eradication of H. pylori. In regions with accessible local research evidence, the 10-day empirical BQT regimen may be considered a preferred choice for H. pylori eradication.

UNASSIGNED: Klebsiella pneumoniae, a gram-negative bacterium, poses a severe hazard to public health, with many bacterial hosts having developed resistance to most antibiotics in clinical use. The goal of this study was to look into the development of resistance to both ceftazidime-avibactam and carbapenems, including imipenem and meropenem, in a K. pneumonia strain expressing a novel K. pneumoniae carbapenemase-2 (KPC-2) variant, referred to as KPC-49.
UNASSIGNED: After 1 day of incubation of K1 on agar containing ceftazidime-avibactam (MIC = 16/4 mg/L), a second KPC-producing K. pneumoniae strain (K2) was recovered. Antimicrobial susceptibility assays, cloning assays, and whole genome sequencing were performed to analyse and evaluate antibiotic resistance phenotypes and genotypes.
UNASSIGNED: K. pneumoniae strain (K1), that produced KPC-2, was susceptible to ceftazidime-avibactam but resistant to carbapenems. The K2 isolate harboured a novel bla KPC-49 variant, which differs from bla KPC-2 by a single nucleotide (C487A), and results in an arginine-serine substitution at amino acid position 163 (R163S). The mutant K2 strain was resistant to both ceftazidime-avibactam and carbapenems. We demonstrated the ability of KPC-49 to hydrolyse carbapenems, which may be attributed to high KPC-49 expression or presence of an efflux pump and/or absence of membrane pore proteins in K2. Furthermore, blaKPC-like was carried on an IncFII (pHN7A8)/IncR-type plasmid within a TnAs1-orf-orf-orf-orf-orf-orf-ISKpn6-bla KPC-ISKpn27 structure. The bla KPC-like gene was flanked by various insertion sequences and transposon elements, including the Tn3 family transposon, such as TnAs1, TnAs3, IS26, and IS481-ISKpn27.
UNASSIGNED: New KPC variants are emerging owing to sustained exposure to antimicrobials and modifications in their amino acid sequences. We demonstrated the drug resistance mechanisms of the new mutant strains through experimental whole genome sequencing combined with bioinformatics analysis. Enhanced understanding of laboratory and clinical features of infections due to K. pneumoniae of the new KPC subtype is key to early and accurate anti-infective therapy.

UNASSIGNED: To evaluate the performance of five widespread commercial products for colistin and polymyxin B susceptibility testing in China for mcr-positive and -negative Escherichia coli and Klebsiella pneumoniae.
UNASSIGNED: A total of 132 E. coli and 83 K. pneumoniae strains (including 68 mcr-1-positive E. coli and 28 mcr-8-positive K. pneumoniae) were collected. We analysed the performance of colistin susceptibility (with Vitek 2 and Phoenix M50) and the performance of polymyxin B susceptibility (with DL-96II, MA120, and a Polymyxin B Susceptibility Test strip; POL E-strip). Broth microdilution was used as the gold standard. Categorical agreement (CA), essential agreement (EA), major error (ME), and very major error (VME) were calculated for comparisons.
UNASSIGNED: For E. coli, the total CA, EA, ME, and VME to colistin were as follows: Vitek 2, 98.5%/98.5%/0%/2.9%; and Phoenix M50, 98.5%/97.7%/0%/2.9%. The total CA, EA, ME, and VME to polymyxin B were as follows: POL E-strip, 99.2%/63.6%/1.6%/0%; MA120, 70.0%/-/0%/58.8%; and DL-96II, 80.2%/-/1.6%/36.8%. Only Vitek 2 and Phoenix M50 presented satisfactory performances for mcr-1-positive E. coli. For K. pneumoniae, the total CA, EA, ME, and VME to colistin were as follows: Vitek 2, 73.2%/72.0%/0%/61.6%; and Phoenix M50, 74.7%/74.7%/0%/58.3%. The total CA, EA, ME, and VME to polymyxin B were as follows: POL E-strip, 91.6%/74.7%/2.1%/16.7%; MA120, 92.8%/-/2.1%/13.9%; and DL-96II, 92.2%/-/2.1%/8.3%. All systems were unsatisfactory for mcr-8-positive K. pneumoniae. When the susceptibility of mcr-negative strains was tested, all systems presented excellent performance.
UNASSIGNED: Vitek 2 and Phoenix M50 with colistin for E. coli showed acceptable performance regardless of mcr-1 expression, while DL-96II, MA120, and the POL E-strip performed worse for mcr-1-positive strains. Furthermore, mcr-8 greatly affected the performance of all systems with both colistin and polymyxin B for K. pneumoniae isolates.

UNASSIGNED: Unsatisfactory efficacies of currently recommended anti-Mycobacterium abscessus complex (MABC) treatment regimens have led to development of novel drugs to combat MABC infections. In this study, we evaluated in vitro antimicrobial activities of bedaquiline (BDQ) and four oxazolidinones against MABC isolates.
UNASSIGNED: The resazurin microplate assay was performed to determine minimum inhibitory concentrations (MICs) of BDQ and four oxazolidinones, including tedizolid (TZD), sutezolid (SZD), delpazolid (DZD), and linezolid (LZD), against 65 MABC isolates. A checkerboard method was used to investigate efficacies of various antimicrobial drug combinations.
UNASSIGNED: BDQ MICs for MABC isolates ranged from <0.031 to 1 µg/mL, while MIC50 and MIC90 values were 0.125 µg/mL and 0.25 µg/mL, respectively. TZD MIC50 and MIC90 values for MABC isolates were 1 µg/mL and 4 µg/mL, respectively, which were fourfold lower than corresponding LZD values (P < 0.001). DZD MIC90 values for MABC isolates was 8 µg/mL, which were 0.5-fold lower than corresponding LZD values (P < 0.01). MICs of BDQ, SZD, and LZD for M. abscessus subspecies massiliense isolates were significantly lower than corresponding MICs for M. abscessus subspecies abscessus isolates (P < 0.05). Notably, use of oxazolidinones (DZD, SZD, LZD, or TZD) with BDQ against MABC isolates led to reduction of the oxazolidinone median MIC range from 4 to 0.125 µg/mL to 1-0.031 µg/mL.
UNASSIGNED: These results demonstrated excellent BDQ inhibitory activity against MABC isolates. TZD exhibited stronger antimicrobial efficacy against MABC isolates as compared to efficacies of DZD, SZD, and LZD. Importantly, MICs of oxazolidinones were markedly decreased when they were combined with BDQ, thus suggesting that combinations of BDQ and oxazolidinones may be effective treatments for MABC infections.

UNASSIGNED: Nontuberculous mycobacteria (NTM) can cause pulmonary and extrapulmonary diseases. Tedizolid (TZD) is a new oxazolidinone with in vitro activity against NTM such as Mycobacterium avium complex (MAC), Mycobacterium fortuitum, and Mycobacterium abscessus complex. The aim of this study was to evaluate the TZD susceptibility profiles of clinical isolates of NTM.
UNASSIGNED: The microdilution method was used to identify the minimum inhibitory concentration (MIC) of TZD and linezolid (LZD) for 133 clinical NTM isolates. Broth microdilution chequerboard assays were used to investigate the synergistic effects of TZD and three antibiotics on two reference isolates and eleven clinical isolates of NTM.
UNASSIGNED: The TZD MIC50 and MIC90 for M. abscessus complex were 2 and 4 μg/mL, 16 and >32 μg/mL for MAC, respectively. TZD exhibited lower MICs than that of LZD for most NTM, which were positively correlated. Due to the high MIC values of TZD against MAC, it is necessary to conduct drug sensitivity tests before TZD administration. TZD-clarithromycin combination had synergistic response on M. abscessus complex in 3 of the 8 isolates, which lasted only 3-5 days. TZD-cefoxitin had synergistic effect against all five M. fortuitum isolates.
UNASSIGNED: Our study demonstrates that TZD had greater in vitro potency than LZD, and synergy studies suggested that TZD may be an important component of multi-drug treatment regimen.

Ceftazidime-avibactam (CZA), a novel β-lactam/β-lactamase inhibitor combination, has good antibacterial activity against carbapenem-resistant Enterobacterales (CRE) producing class A and C and some class D carbapenemases, but in recent years, the emergence of CZA-resistant Enterobacterales bacteria is growing. Therefore, rapid, accurate, and timely detection of CZA is necessary for clinical anti-infection treatment. In this study, the rapid ResaCeftazidime-avibactam Enterobacterales NP test was developed; its principle is that metabolically active bacteria (CZA-resistant strains) can change resazurin-PrestoBlue, a viability colorant, from blue to purple or pink in the presence of CZA, whereas CZA-susceptible strains cannot. We used 178 Enterobacterales isolates to evaluate the performance of this test. This test allowed the susceptibility of Enterobacterales to CZA to be detected within 4.5 h with an overall performance of 96% category agreement (CA), 7% major errors (MEs), and 0% very major errors (VMEs). Performance for Escherichia coli included 100% CA and 0% MEs and VMEs. Performance for Klebsiella pneumoniae included 99% CA and 2% MEs and 0% VMEs. Performance for Enterobacter cloacae included 87% CA, 25% MEs, and 0% VMEs. Moreover, this test is both economical ($1.0106 per isolate) and convenient, as it only requires basic laboratory equipment. In a word, the rapid ResaCeftazidime-avibactam Enterobacterales NP test is rapid and feasible, which may provide certain backing for the rapid screening and timely treatment of CZA-resistant strains in the clinic.

Avibacterium (Av.) gallinarum is an opportunistic pathogen in poultry, which, however, has also been associated with human disease. There is currently no approved method for antimicrobial susceptibility testing of this pathogen, so this study aimed at developing a harmonized broth microdilution method for Av. gallinarum that is suitable for diagnostic laboratories. For this, the Av. gallinarum CCUG 12391T type strain and 42 field isolates were collected and their species was confirmed by using a species-specific PCR assay and biochemical reactions. To select epidemiologically unrelated isolates, ApaI macrorestriction analysis was performed. Preliminary growth experiments were conducted with six culture media, and based on the results, four media were selected to compile growth curves with four isolates. Independent repetitions of MIC determinations were then performed to evaluate the reproducibility of the values. Cation-adjusted Mueller-Hinton broth (CAMHB) was initially selected as broth medium, but did not show sufficient homogeneity of MICs. Therefore, CAMHB plus 1% chicken serum and 0.0025% NADH was selected and showed a good homogeneity of MICs after 20 h and 24 h of incubation at 35 ± 2°C. This was reflected in essential MIC agreements ranging between 96% and 100%. Testing of a larger Av. gallinarum collection (n = 43) revealed that easily readable MICs could be obtained for the type strain and all isolates. Some Av. gallinarum showed elevated MICs of enrofloxacin (n = 35), nalidixic acid (n = 35), penicillin (n = 2), tetracycline (n = 19), and/or trimethoprim-sulfamethoxazole (n = 1). By using PCR analyses, the following antimicrobial resistance genes were detected: blaTEM, dfrA14, sul2, tet(B), tet(H). The study demonstrated that the proposed medium is suitable for a harmonized broth microdilution susceptibility testing of Av. gallinarum with a recommended incubation time of 20 to 24 h.

Conventional turnaround time (TAT) for positive blood culture (PBC) identification (ID) and antimicrobial susceptibility testing (AST) is 2-3 days. We evaluated the TAT and ID/AST performance using clinical and seeded samples directly from PBC bottles with different commercial approaches: (1) Accelerate Pheno® system (Pheno) for ID/AST; (2) BioFire® FilmArray® Blood Culture Identification (BCID) Panel and/ or BCID2 for ID; (3) direct AST by VITEK® 2 (direct AST); and (4) overnight culture using VITEK® 2 colony AST.
A total of 141 PBC samples were included in this evaluation. Using MALDI-TOF (Bruker MALDI Biotyper) as the reference method for ID, the overall monomicrobial ID sensitivity/specificity are as follows: Pheno 97.9/99.9%; BCID 100/100%; and BCID2 100/100%, respectively. For AST performance, broth microdilution (BMD) was used as the reference method. For gram-negatives, overall categorical and essential agreements (CA/EA) for each method were: Pheno 90.3/93.2%; direct AST 92.6/88.5%; colony AST 94.4/89.5%, respectively. For gram-positives, the overall CA/EAs were as follows: Pheno 97.2/98.89%; direct AST 97.2/100%; colony AST 97.2/100%, respectively. The BCID/BCID2 and direct AST TATs were around 9-20 h (1/9-19 h for ID with resistance markers/AST), with 15 min/sample hands-on time. In comparison, Pheno TATs were around 8-10 h (1.5/7 h for ID/AST) with 2 min/sample hands-on time, maintains a clinically relevant fast report of antibiotic minimal inhibitory concentration (MIC) and allows for less TAT and hands-on time.
In conclusion, to the best of our knowledge, this is the first study conducted as such in Asia; all studied approaches achieved satisfactory performance, factors such as TAT, panel of antibiotics choices and hands-on time should be considered for the selection of appropriate rapid ID and AST of PBC methods in different laboratory settings.

BACKGROUND: Dermatophytes are the most common fungal pathogens causing superficial infections in humans with a high prevalence worldwide. The treatment of these infections is based on the use of topical and systemic antifungal agents. A convenient method with a high predictive value for testing the susceptibilities of dermatophytes is necessary.
OBJECTIVE: To evaluate the ability of the Sensititre YeastOne® in testing the activity of nine antifungal agents against dermatophytes.
METHODS: We compared Sensititre® with reference procedure for anidulafungin (ANID), micafungin sodium (MCF), caspofungin acetate (CAS), 5-fluorocytosine (5FC), posaconazole (PCZ), voriconazole (VCZ), itraconazole (ITZ), fluconazole (FLZ) and amphotericin B (AMB) against 79 dermatophyte isolates, the essential agreement (EA) and categorical agreement (CA) between the two methods were obtained.
RESULTS: The MICs or MECs obtained by the Sensititre® were usually lower than those obtained by the M38-A2. The overall EA between the two methods of nine antifungals was best for 5FC (100%), followed by MCF (94.9%), PCZ (84.8%), AMB (67.1%), FLZ (65.8%), VCZ (63.3%), ANID (29.1%), ITZ (20.3%) and CAS (2.5%). The overall CA between the two methods for all drugs was 100% except for ANID (97.4%), MCF (95%) and PCZ (92.5%). Substantial discrepancies were observed with all drugs except for VCZ and 5FC. The results of M38-A2 in terms of GMIC (or GMEC) and MIC90 (or MEC90) were, in increasing order, as follows: MCF, PCZ, VCZ, ANID, ITZ, CAS, AMB, FLZ and 5FC.
CONCLUSIONS: The Sensititre YeastOne® shows poor EA with the reference method for dermatophytes; therefore, M38-A2 should remain the reference procedure for antifungal susceptibility testing against dermatophytes.