Introduction. Klebsiella spp. are important bacteria that colonize the human intestine, especially in preterm infants; they can induce local and systemic disease under specific circumstances, including inflammatory bowel disease, necrotizing enterocolitis and colorectal cancer.Hypothesis. Klebsiella spp. colonized in the intestine of the neonates in the neonatal intensive care unit (NICU) may be associated with disease and antibiotic resistance, which will be hazardous to the children.Aim. Our aim was to know about the prevalence, antimicrobial resistance and genome characteristics of Klebsiella spp. in neonate carriers.Methodology. Genome sequencing and analysis, and antimicrobial susceptibility testing were mainly performed in this study.Results. The isolation rates of Klebsiella spp. strains were 3.7% (16/436) in 2014 and 4.3% (18/420) in 2021. Cases with intestinal-colonized Klebsiella spp. were mainly infants with low birth weights or those with pneumonia or hyperbilirubinemia. According to the core-pan genomic analysis, 34 stains showed gene polymorphism and a sequence type (ST) of an emerging high-risk clone (ST11). Eight strains (23.5%) were found to be resistant to 2 or more antibiotics, and 46 genes/gene families along with nine plasmids were identified that conferred resistance to antibiotics. In particular, the two strains were multidrug-resistant. Strain A1256 that is related to Klebsiella quasipneumoniae subsp. similipneumoniae was uncommon, carrying two plasmids similar to IncFII and IncX3 that included five antibiotic resistance genes.Conclusion. The prevention and control of neonatal Klebsiella spp. colonization in the NICU should be strengthened by paying increased attention to preventing antimicrobial resistance in neonates.

Tuberculosis (TB) caused by bacteria of the Mycobacterium tuberculosis complex remains one of the most important infectious diseases of mankind. Rifampicin is a first line drug used in multi-drug treatment of TB, however, the necessary duration of treatment with these drugs is long and development of resistance is an increasing impediment to treatment programmes. As a result, there is a requirement for research and development of new TB drugs, which can form the basis of new drug combinations, either due to their own anti-mycobacterial activity or by augmenting the activity of existing drugs such as rifampicin. This study describes a TnSeq analysis to identify mutants with enhanced sensitivity to sub-minimum inhibitory concentrations (MIC) of rifampicin. The rifampicin-sensitive mutants were disrupted in genes of a variety of functions and the majority fitted into three thematic groups: firstly, genes that were involved in DNA/RNA metabolism, secondly, genes involved in sensing and regulating mycobacterial cellular systems, and thirdly, genes involved in the synthesis and maintenance of the cell wall. Selection at two concentrations of rifampicin (1/250 and 1/62 MIC) demonstrated a dose response for mutants with statistically significant sensitivity to rifampicin. The dataset reveals mechanisms of how mycobacteria are innately tolerant to and initiate an adaptive response to rifampicin; providing putative targets for the development of adjunctive therapies that potentiate the action of rifampicin.

The current therapies against gastric pathogen Helicobacter pylori are ineffective in over 20% of patients. Enzymes belonging to the purine salvage pathway are considered as novel drug targets in this pathogen. Therefore, the main aim of the current study was to determine the antibacterial activity of pyridoxal 5\'-phosphate (PLP), an active form of vitamin B6, against reference and clinical strains of H. pylori. Using a broad set of microbiological, physicochemical (UV absorption, LC-MS, X-ray analysis) and in silico experiments, we were able to prove that PLP inhibits adenylosuccinate synthetase (AdSS) from H. pylori by the competition with GTP (IC50eq ∼30 nM). This behaviour was attributed to formation of a Schiff base with a lysine residue (a covalent bond with Lys322 in the GTP binding site of AdSS) and was potentiated by the presence of vitamin C. This antibacterial activity of PLP gives hope for its future use against H. pylori.

Staphylococcus aureus infection and colonization in patients may be transmitted to healthcare providers and the environment and subsequently cause healthcare-associated infections in other patients. Pathogenic S. aureus strains produce virulence factors, such as Panton-Valentine Leukocidin (PVL), that contribute to the severity of infections and aid in their spread. The emergence of antimicrobial resistance (AMR) is additional concern with respect to S. aureus infection. In this study, the virulence genes and antibiotic resistance profiles of S. aureus were characterized from patients\' clinical isolates, healthcare workers\' (HCWs\') nasal colonization screenings, and the environment at a tertiary healthcare hospital in Addis Ababa, Ethiopia. A total of 365 samples were collected from September 2021 to September 2022: 73 patients\' clinical specimens, 202 colonization screenings from HCWs, and 90 hospital environment\'s swabs. Fifty-one (25.2%) HCW and 10/90 (11.1%) environment S. aureus isolates were identified. Among the 134 isolates, 10 (7.5%) were methicillin-resistant S. aureus (MRSA). Three (4.1%), five (9.8%), and two (20.0%) of the MRSA isolates were identified from the patients, HCWs, and the environment, respectively. Overall, 118 (88.1%) were ampicillin and penicillin resistant; 70 (52.2%) were trimethoprim sulfamethoxazole resistant; and 28 (20.9%) were erythromycin resistant. S. aureus isolates from patients were more resistant to antibiotics than isolates from HCWs or the hospital environment (p<0.05). A total of 92/134 (68.6%) isolates possessed the lukfF-PV gene, which was identified in 62 (85.0%), 26 (51.0%), and 4 (40.0%) of the patient, HCWs, and the environment, respectively. The proportion of lukfF-PV gene containing S. aureus isolated from patient samples was statistically significant. Four (40.0%) of the MRSA isolates also had the lukfF-PV gene. The identification of highly AMR and virulence factors from patients, HCWs and the environment is concerning. Further studies are needed to identify potential transmission links and improve infection prevention and control.

BACKGROUND: The optimal duration of regimens for tailored therapy based on genotypic resistance for clarithromycin has yet to be established.
OBJECTIVE: This study was a nationwide, multicenter, randomized trial comparing empirical therapy with tailored therapy based on genotypic resistance for first-line eradication of Helicobacter pylori. We also compared the eradication rates of 7- and 14-day regimens for each group.
METHODS: Patients with H. pylori infection were first randomized to receive empirical or tailored therapy. Patients in each group were further randomized into 7- or 14-day regimens. Empirical therapy consisted of a triple therapy (TT) regimen (twice-daily doses of pantoprazole 40 mg, amoxicillin 1 g, and clarithromycin 500 mg) for 7 or 14 days. Tailored therapy consisted of TT of 7 or 14 days in patients without genotypic resistance. Patients with genotypic resistance were treated with bismuth quadruple therapy (BQT) regimens (twice-daily doses of pantoprazole 40 mg, three daily doses of metronidazole 500 mg, and four times daily doses of bismuth 300 mg and tetracycline 500 mg) for 7 or 14 days. A 13C-urea breath test assessed eradication rates. The primary outcome was eradication rates of each group.
RESULTS: A total of 593 patients were included in the study. The eradication rates were 65.7% (201/306) in the empirical therapy group and 81.9% (235/287) in the tailored therapy group for intention-to-treat analysis (p < 0.001). In the per-protocol analysis, the eradication rates of the empirical therapy and tailored groups were 70.3% (201/286) and 85.5% (235/274) (p < 0.001), respectively. There was no difference in compliance between the two groups. The rate of adverse events was higher in the tailored group compared to the empirical group (p < 0.001).
CONCLUSIONS: Our study confirmed that tailored therapy based on genotypic resistance was more effective than empirical therapy for H. pylori eradication in Korea. However, no significant difference was found between 7- and 14-day regimens for each group. Future studies are needed to determine the optimal duration of therapy for empirical and tailored therapy regimens.

BACKGROUND: The purpose of this study was to look into the presence of plasmid-mediated quinolone resistance (PMQR) genes and biofilm formation in several species of clinical Shigella isolates that were resistant to quinolones.
METHODS: The stool samples of 150 patients (younger than 10 years) with diarrhea were collected in this cross-sectional study (November 2020 to December 2021). After cultivation of samples on Hektoen Enteric agar and xylose lysine deoxycholate agar, standard microbiology tests, VITEK 2 system, and polymerase chain reaction (PCR) were utilized to identify Shigella isolates. The broth microdilution method was used to determine antibiotic susceptibility. PMQR genes including qnrA, qnrB, qnrC, qnrD, qnrE, qnrS, qnrVC, qepA, oqxAB, aac(6\')-Ib-cr, and crpP and biofilm formation were investigated in quinolone-resistant isolates by PCR and microtiter plate method, respectively. An enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) technique was used to determine the clonal relatedness of quinolone-resistant isolates.
RESULTS: A total of 95 Shigella isolates including S. sonnei (53, 55.8%), S. flexneri (39, 41.1%), and S. boydii (3, 3.2%) were identified. The highest resistance rates of the isolates were against ampicillin (92.6%, n = 88/95). Overall, 42 of 95 (44.2%) isolates were simultaneously resistant against two or more quinolones including 26 (61.9%) S. sonnei and 16 (38.1%) S. flexneri. All isolates were multidrug-resistant (resistance to more than 3 antibiotics). The occurrence of PMQR genes was as follows: qnrS (52.4%), qnrA and aac(6\')-Ib-cr (33.3%), and qnrB (19.0%). The prevalence in species was as follows: 61.5% and 37.5% (qnrS), 19.2% and 56.3% (qnrA), 38.5% and 25.0 (aac(6\')-Ib-cr), and 19.2% and 18.8% (qnrB) for S. sonnei and S. flexneri, respectively. The other PMQR genes were not detected. In total, 52.8% (28/53) of quinolone-susceptible and 64.3% (27/42) of quinolone-resistant isolates were biofilm producers. Biofilm formation was not significantly different between quinolone-resistant and quinolone-susceptible isolates (P-value = 0.299). Quinolone-resistant isolates showed a high genetic diversity according to the ERIC-PCR.
CONCLUSIONS: It seems that qnrS, qnrA, and aac(6\')-Ib-cr play a significant role in the quinolone resistance among Shigella isolates in our region. Also the quinolone-resistant S. flexneri and S. sonnei isolates had a high genetic diversity. Hence, antibiotic therapy needs to be routinely revised based on the surveillance findings.

BACKGROUND: The global probiotics dietary supplements market size is continuously growing. To overcome probiotics\' health concerns, metabiotics are recognized as a safer alternative. Aiming to deal with the escalating antimicrobial resistance, the current work demonstrates synergistic metabiotic-antibiotic combinations against antibiotic-resistant pathogens.
METHODS: The probiotic properties of lactic acid bacteria (LAB) strains isolated from 3 commercial dietary supplements were characterized in vitro. The combinations of the cell-free supernatants (CFS) of selected probiotic strains and conventional antibiotics against Staphylococcus aureus and Escherichia coli clinical isolates were evaluated using the time-kill assay. To our knowledge, the current literature lacks sufficient time-kill assay studies revealing the kinetics of such metabiotic-antibiotic combinations against S. aureus and E. coli.
RESULTS: Four LAB strains isolated from dietary supplements as well as two reference strains were included in this study. The isolated LAB strains were identified by MALDI-TOF mass spectrometry as follows: P2: Lactobacillus acidophilus, P3: Lactiplantibacillus plantarum, P4: Lacticaseibacillus rhamnosus, and P5: Pediococcus acidilactici. The identification matched with that annotated by the manufacturers, except for P3. The tested strains could resist the acidic environment at pH 3. Excluding P2, the examined strains showed less than 1 log reduction in survivors upon the addition of reconstituted skimmed milk to pepsin at pH 2 and displayed an acceptable tolerance to 0.3% ox-bile. All the strains tolerated pancreatin. The hydrophobicity and autoaggregation capacities ranged between 7-92% and 36-66%, respectively. P2 was excluded owing to its inferior probiotic potential. Although the remaining strains showed excellent growth at 0.2% phenol, their growth was reduced at higher concentrations. L. plantarum and P. acidilactici strains possessed bile salt hydrolysis activity. The time-kill assay revealed promising synergistic activities of the combinations of CFS of L. rhamnosus P4 with either ceftazidime or gentamicin against E. coli and with only ceftazidime against S. aureus, as well as CFS of P. acidilactici P5 and ceftazidime against S. aureus.
CONCLUSIONS: Strict identification and evaluation of the probiotic strains incorporated in dietary supplements is crucial to ensure their safety and efficacy. The CFS of probiotics could be utilized to formulate novel biotherapeutics targeting problematic pathogens. However, future in vivo studies are required to evaluate the appropriate treatment regimen.

Antibiotics may alter the gut microbiome, and this is one of the mechanisms by which antimicrobial resistance may be promoted. Suboptimal antimicrobial stewardship in Asia has been linked to antimicrobial resistance. We aim to examine the relationship between oral antibiotic use and composition and antimicrobial resistance in the gut microbiome in 1093 Bangladeshi infants. We leverage a trial of 8-month-old infants in rural Bangladesh: 61% of children were cumulatively exposed to antibiotics (most commonly cephalosporins and macrolides) over the 12-month study period, including 47% in the first 3 months of the study, usually for fever or respiratory infection. 16S rRNA amplicon sequencing in 11-month-old infants reveals that alpha diversity of the intestinal microbiome is reduced in children who received antibiotics within the previous 7 days; these samples also exhibit enrichment for Enterococcus and Escherichia/Shigella genera. No effect is seen in children who received antibiotics earlier. Using shotgun metagenomics, overall abundance of antimicrobial resistance genes declines over time. Enrichment for an Enterococcus-related antimicrobial resistance gene is observed in children receiving antibiotics within the previous 7 days, but not earlier. Presence of antimicrobial resistance genes is correlated to microbiome composition. In Bangladeshi children, community use of antibiotics transiently reprofiles the gut microbiome.

To investigate the strain composition and drug resistance characteristics of G+(Gram positive cocci) cocci causing bloodstream infections in the People\'s Hospital of Inner Mongolia Autonomous Region in recent years and provide a basis for the empirical and rational use of drugs for the prevention and treatment of bloodstream infections caused by G+cocci. The strain composition and drug-resistant characteristics of G+cocci isolated from positive blood culture specimens sent to various departments of the Inner Mongolia Autonomous Region People\'s Hospital from January 2015 to December 2022 were retrospectively analyzed, and the higher detection rates of Staphylococcus hominis and Staphylococcus epidermidis, Enterococcus faecium and Enterococcus faecalis, and methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) were examined. MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) were comparatively analyzed for resistance. The resistance data were analyzed by Whonet 5.6 statistical software, the significance of difference was analyzed by SPSS 22.0 software, and the resistance rate was compared by χ2 test. The results showed that 1 209 strains of G+cocci, in terms of the composition ratio, from high to low, were mainly human staphylococci (32.5%,393/1 209), Staphylococcus epidermidis (27.8%, 336/1 209), Staphylococcus aureus (14.9%,180/1 209) and Enterococcus faecalis (10.6%, 128/1 209). Among them, the detection rate of methicillin-resistant Staphylococcus aureus (MRSA) (42.8%, 77/180) was lower than that of methicillin-resistant coagulase-negative staphylococcus (MRCNS) (71.5%, 608/850); and among enterococci, the detection rate of Enterococcus faecalis (71.5%, 128/179) was much higher than that of Enterococcus faecalis (28.5%, 51/179). For drug resistance, the resistance rate to five commonly used antimicrobial drugs, ciprofloxacin, levofloxacin, moxifloxacin, clindamycin and tetracycline, was higher in Staphylococcus hominis than in Staphylococcus epidermidis (χ2=7.152-64.080, P<0.05); however, for the aminoglycoside antimicrobial drug gentamicin, the rate of resistance in Staphylococcus humanus was lower than in Staphylococcus epidermidis, and the difference was statistically significant (χ2=11.895, P<0.05); no strains resistant to linezolid and vancomycin were found in both. Comparison of the resistance rates to seven antimicrobial drugs, gentamicin, rifampicin, ciprofloxacin, levofloxacin, moxifloxacin, clindamycin and tetracycline, was significantly higher in MRSA than in MSSA (χ2=6.169-56.941, P<0.05); however, the resistance rate to cotrimoxazole, MRSA (15.6%, 12/77) was significantly lower than that of MSSA (35.3%, 36/102), and the difference was statistically significant (χ2=5.155, P<0.05); MRSA and MSSA resistant to linezolid and vancomycin were not found. The resistance rate of Enterococcus faecalis to penicillin G and ampicillin was much higher than that of Enterococcus faecalis, and the difference was statistically significant (χ2=22.965, P<0.05), and vancomycin-resistant enterococci (VRE) were not found. In conclusion, for staphylococci, except for individual antibiotics, S.hominis and MRSA were more resistant to most antimicrobial drugs than S. epidermidis and MSSA, showing a multidrug-resistant pattern. For enterococci, except for penicillin G and ampicillin resistance rate, Enterococcus faecalis is much higher than Enterococcus faecalis, the rest of the antimicrobial drugs did not see a significant difference, in addition to vancomycin-resistant enterococci were not detected. Clinicians should pay great attention to the monitoring data of multidrug-resistant G+cocci isolated from blood cultures to provide a basis for empirical and rational use of drugs in the clinic, to effectively prevent and reduce the incidence of bloodstream infections caused by G+cocci.
探讨内蒙古某医院引起血流感染革兰阳性球菌（Gram positive cocci，G+球菌）的菌种构成及耐药特点，为合理用药提供依据。对2015年1月至2022年12月内蒙古自治区人民医院各科室送检血培养阳性标本分离出的G+球菌的菌种构成和耐药情况进行回顾性分析，对检出率较高的人葡萄球菌和表皮葡萄球菌、屎肠球菌和粪肠球菌及甲氧西林耐药金黄色葡萄球菌（MRSA）和甲氧西林敏感的金黄色葡萄球菌（MSSA）的耐药性进行对比分析。耐药数据采用Whonet 5.6统计软件进行分析，差异显著性分析采用SPSS 22.0软件，耐药率比较采用χ2检验。结果显示，1 209株G+球菌，在构成比方面，从高到低主要有人葡萄球菌（32.5%，393/1 209）、表皮葡萄球菌（27.8%，336/1 209）、金黄色葡萄球菌（14.9%，180/1 209）和屎肠球菌（10.6%，128/1 209）。其中，耐甲氧西林金黄色葡萄球菌（MRSA）的检出率（42.8%，77/180）低于耐甲氧西林凝固酶阴性葡萄球菌（MRCNS）的检出率（71.5%，608/850）；肠球菌中，屎肠球菌（71.5%，128/179）的检出率远高于粪肠球菌（28.5%，51/179）。耐药性方面，对环丙沙星、左旋氧氟沙星、莫西沙星、克林霉素和四环素5种常用抗菌药物的耐药率，人葡萄球菌高于表皮葡萄球菌（χ2=7.152~64.080，P<0.05）；但对氨基糖苷类抗菌药物庆大霉素的耐药率，人葡萄球菌低于表皮葡萄球菌，差异有统计学意义（χ2=11.895，P<0.05）；两者均未发现对利奈唑胺和万古霉素耐药的菌株。对庆大霉素、利福平、环丙沙星、左旋氧氟沙星、莫西沙星、克林霉素和四环素7种抗菌药物的耐药率比较，MRSA明显高于MSSA（χ2=6.169~56.941，P<0.05）；但对复方磺胺甲噁唑（药物的成分为磺胺甲噁唑和甲氧苄啶）的耐药率，MRSA（15.6%，12/77）明显低于MSSA（35.3%，36/102），差异有统计学意义（χ2=5.155，P<0.05）；未发现对利奈唑胺和万古霉素耐药的MRSA和MSSA。屎肠球菌对青霉素G和氨苄西林的耐药率远高于粪肠球菌，差异有统计学意义（χ2=22.965，P<0.05）；未发现对万古霉素耐药的肠球菌。综上，对于葡萄球菌，除个别抗生素外，人葡萄球菌、MRSA对大多数抗菌药物的耐药率要高于表皮葡萄球菌和MSSA，呈多重耐药的态势。对于肠球菌，只有对青霉素G和氨苄西林耐药率，屎肠球菌远高于粪肠球菌，其余抗菌药物均未见明显差异，另外未检出对万古霉素耐药的肠球菌。.

The antibacterial oxidative response, which relies on the production of hydrogen peroxide (H2O2) and hypothiocyanite (OSCN-), is a major line of defense protecting the human airway epithelium (HAE) from lesions when infected. The in vitro studies of the oxidative responses are performed mainly by one-shot H2O2 exposure that does not recapitulate the complex H2O2/LPO/SCN- system releasing the reactive oxygen species in airway secretions. A cell-free in vitro assay mimicking this system has been described but was not fully characterized. Here, we comprehensively characterized the hourly H2O2/OSCN- concentrations produced within this in vitro assay and assessed the resistance of Pseudomonas aeruginosa and Staphylococcus aureus clinical strains to the HAE oxidative response. We found that H2O2/OSCN- were steadily produced from 7h and up to 25h, but OSCN- was detoxified in 15 minutes by bacteria upon exposure. Preliminary tests on PA14 showed survival rates at 1-hour post-exposure (hpe) to H2O2 of roughly 50% for 105 and 107 colony-forming unit (CFU)/mL inocula, while 102 and 104 CFU/mL inocula were cleared after one hpe. Thirteen clinical strains were then exposed, highlighting that conversely to P. aeruginosa, S. aureus showed resistance to oxidative stress independently of its antibiotic resistance phenotype. Our results demonstrated how this in vitro assay can be helpful in assessing whether pathogens can resist the antibacterial oxidative HAE response. We anticipate these findings as a starting point for more sophisticated in vitro models that could serve as high-throughput screening for molecules targeting the bacterial antioxidant response.