BACKGROUND: With the widespread use of antibiotics, more attention has been paid to their side effects. We paid extra attention to the impact of antibiotics on children\'s bodies. Therefore, we analyzed the characteristic changes in the gut microbiota of children after antibiotic treatment to explore the pathogenesis of antibiotic-associated diseases in more depth and to provide a basis for diagnosis and treatment.
METHODS: We recruited 28 children with bronchopneumonia in the western district of Zhuhai, China, and divided them into three treatment groups based on antibiotic type. We took stool samples from children before and 3-5 days after antibiotic treatment. 16S rRNA gene sequencing was used to analyze the effects of antibiotic therapy on the gut microbiota of children. Continuous nonparametric data are represented as median values and analyzed using the Wilcoxon rank-sum test.
RESULTS: While alpha diversity analysis found no significant changes in the mean abundance of the gut microbiota of children after a short course of antibiotic treatment, beta diversity analysis demonstrated significant changes in the composition and diversity of the gut microbiota of children even after a short course of antibiotic therapy. We also found that meloxicillin sulbactam can inhibit the growth of Proteobacteria, Bacteroidetes, and Verrucomicrobia, ceftriaxone inhibits Verrucomicrobia and Bacteroides, and azithromycin inhibits Fusobacteria, Actinobacteria, Proteobacteria, and Verrucomicrobia. We further performed a comparative analysis at the genus level and found significantly different clusters in each group. Finally, we found that azithromycin had the greatest effect on the metabolic function of intestinal microbiota, followed by ceftriaxone, and no significant change in the metabolic process of intestinal microbiota after meloxicillin sulbactam treatment.
CONCLUSIONS: Antibiotic treatment significantly affects the diversity of intestinal microbiota in children, even after a short course of antibiotic treatment. Different classes of antibiotics affect diverse microbiota primarily, leading to varying alterations in metabolic function. Meanwhile, we identified a series of intestinal microbiota that differed significantly after antibiotic treatment. These groups of microbiota could be used as biomarkers to provide an additional basis for diagnosing and treating antibiotic-associated diseases.

This case report describes the case of a female infant hospitalized for severe pneumonia. During the treatment process, various antibiotics are used to treat and prevent further infection. The child had a weak physical condition, combined with neuroblastoma, paraneoplastic syndrome, and low immune function, leading to Tsukamurella tyrosinosolvens infection. The treatment was eventually abandoned owing to poor prognosis. This study aims to through the medium, dyeing, electron microscope observation, 16s rRNA and high-throughput sequencing investigated the morphological characteristics, staining properties, electron microscope morphology, antibiotic resistance, and genomic characteristics of Tsukamurella tyrosinosolvens. The aim of the study is to provide data reference for clinical laboratory staff in bacteria identification research, and to provide relevant help for clinicians in diagnosis and treatment.

Ureaplasma parvum, a member of the Mollicutes class, is a rare but significant pathogen in extragenital infections. This case report is the tenth known case of Ureaplasma spp. peritonitis, occurring in a 36-year-old female post extensive surgery for metastatic sigmoid colon adenocarcinoma. Following the intervention, the patient exhibited post-surgical peritonitis with fever despite empirical broad-spectrum antibiotics. Conventional bacterial and fungal cultures remained negative, prompting the use of 16 S rRNA polymerase chain reaction (PCR) for diagnosis. Ureaplasma parvum was detected in both peritoneal and perihepatic fluid samples, and in the urine, leading to the initiation of doxycycline therapy. The patient responded positively to the treatment, with complete resolution of symptoms and no recurrence observed during a four-year follow-up. This report underscores the clinical challenge posed by Ureaplasma spp. due to its resistance to common antibiotics and difficulty in cultivation. It highlights the importance of molecular diagnostics in identifying such pathogens in culture-negative cases and the necessity of considering Ureaplasma spp. especially in female patients with persistent peritonitis post-urogenital procedures or surgeries. The case also reflects on the limited data regarding antimicrobial susceptibility, emphasizing the need for tailored therapeutic approaches based on local resistance patterns and the clinical context. Ultimately, this case contributes valuable insights into the diagnosis and management of Ureaplasma spp. peritonitis, advocating for heightened clinical suspicion and appropriate molecular testing to ensure effective patient outcomes.

Comamonas kerstersii (C. kerstersii) is a Gram-negative bacterium that was initially thought to be non-pathogenic to humans and is abundant in the environment. In recent years, with the availability of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) that enable fast and accurate bacterial identification, there have been increasing number of reports of human infections caused by C. kerstersii, indicating that this organism has emerged as human pathogen. In fact, most clinical isolates of C. kerstersii are recovered from peritoneal liquid, and bacteremia has been infrequently reported. Here, we report a case of bacteremia caused by C. kerstersii in a 28-year-old male patient with acute perforated appendicitis and localized peritonitis and present a comprehensive review of C. kerstersii infections in pathogenic diagnosis and clinical treatment as well as prognosis, thus providing a better understanding of C. kerstersii-related infections.

Listeria monocytogenes, is a Gram-positive facultative intracellular bacterium without spores. It can cause invasive diseases such as septicemia, meningitis, and encephalitis, and has a high mortality rate. This is a report on a recent case of neurolisteriosis isolated from cerebrospinal fluid sample of a patient with diabetes and chronic heart failure in our hospital. The patient initially received the combined treatment of cephalosporin and meropenem (both 1.0 g every 8 hours). We identified the pathogenic organism as L. monocytogenes using three identification methods: mass spectrometry, biochemical assays, and molecular techniques. After determining the pathogenic bacteria, we quickly informed the clinician and suggesting a change in antibiotic treatment and immediately discontinued cephalosporin and meropenem. The patient\'s symptoms were significantly improved after 9 days of penicillin G treatment, and the patient chose to be discharged for personal reasons. In conclusion, certain strains of wild-type Listeria monocytogenes can lead to identification errors that occur across platforms and methods.

Francisella philomiragia is a Gram-negative coccobacillus, which is a very rare human opportunistic pathogen causing pneumonia and systemic infection. It is difficult to identify this bacterium through conventional Gram-staining and biochemical methods due to an amorphous Gram stain appearance after 24 h culture and its relatively fastidious and slow growth giving weak and/or delayed reactions in biochemical tests. It is often misidentified as other bacteria including Haemophilus spp., Pseudomonas aeruginosa, or Sphingomonas paucimobilis. False identification may delay the therapy of the patients and even endanger the patient\'s life. Here, we report a case of a 34-year-old man with acute lymphoblastic leukemia infected by F. philomiragia, which was almost misdiagnosed. This case describes our identification of a patient with a systemic F. philomiragia infection. To our knowledge, this is the first such case reported in China.

Catheter-associated urinary tract infection (CAUTI) is the most common healthcare-associated infection which tends to cause increased length of morbidity, and mortality of patients, in addition to increased bacterial resistance to antibiotics.
In the present study, urinary catheters were collected from a 50-year-old woman suffering from malignancy, bedridden, and having urinary incontinence. These catheters were processed in laboratory for isolation of bacteria using standard procedures.
Microbiological examination of the urinary catheters by biochemical, physiological, and VITEK 2 compact system revealed bacterial infection caused by Micrococcus lylae, a Gram-positive microorganism belonging to the family Micrococcacea. These Gram-positive bacteria were found to be susceptible to streptomycin, erythromycin, cefotaxime, neomycin, kanamycin, vancomycin, azithromycin, chloramphenicol, and tetracycline. Bacterial species were confirmed using 16s rRNA sequencing.
The sequences were found to have 99% similarity with Micrococcus lylae. This is the first report of isolation of Micrococcus lylae from the urinary catheter.

UNASSIGNED: W. confusa has been known to cause various human infections. It is naturally resistant to vancomycin and is difficult to identify using traditional methods, which may lead to misidentification and delay treatment.
UNASSIGNED: We present a case of a 42-year-old male patient with gastrointestinal bleeding and coronary heart disease who developed sepsis caused by Weissella confusa. The patient\'s blood cultures showed the presence of gram-positive coccobacilli, later identified as W. confusa through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing revealed that W. confusa had low minimum inhibitory concentrations (MICs) for some drugs (eg, ampicillin) and higher MICs for others (eg, cefotaxime). Empirical treatment with vancomycin was initially started, but after obtaining the identification and susceptibility results, the treatment was switched to meropenem combined with daptomycin, resulting in a successful outcome.
UNASSIGNED: Weissella confusa bacteremia is relatively rare, and accurate pathogenic diagnosis is essential for effective clinical treatment.

UNASSIGNED: Christensenella hongkongensis is an obligately anaerobic, catalase-positive, motile, non-sporulating, gram-positive coccobacillus. Human infections are rare and have not been previously reported in Japan. Herein, we report the first case of perforated peritonitis with C. hongkongensis bacteremia in Japan.
UNASSIGNED: A 61-year-old Japanese man with advanced colorectal adenocarcinoma presented with fever and abdominal pain. Abdominal computed tomography revealed a low-density area with thinning of the sigmoid colon wall and air outside the intestinal tract, which was diagnosed as perforated peritonitis. Cultures of the ascitic fluid isolated Bacteroides fragilis, Bacteroides eggerthii, Parabacteroides distasonis, Enterococcus avium, and Candida albicans. Gram-positive rods were detected in the blood culture on admission after 4 days. The isolate was identified as C. hongkongensis via 16S ribosomal RNA (16S rRNA) sequencing. The patient underwent open abdominal washout and drainage via a transverse colon bifurcation colostomy. Intravenous meropenem (3 g/day) was administered for 5 days, followed by intravenous piperacillin-tazobactam (9 g/day) for 6 days, and then levofloxacin (500 mg/day) and metronidazole (1500 mg/day) intravenously for 15 days. Postoperatively, the patient gradually recovered. He was transferred to another palliative care hospital on day 38 after admission for worsening advanced colorectal cancer condition.
UNASSIGNED: Bacteremia caused by C. hongkongensis is rare. 16S rRNA sequencing should be considered for the identification of gram-positive anaerobic rods that are difficult to diagnose by conventional methods.

Cetobacterium somerae, a gram-negative anaerobic rod, first identified in the feces of children with autism, also colonize freshwater fish intestinal tract. However there have been no reports of human C. somerae infection. Here, we describe the first case of C. somerae bacteremia in a patient with necrotizing cholecystitis. A 72-year-old male presented to the emergency department with chills, vomiting, and fever and was diagnosed with acute necrotizing cholecystitis. An emergency cholecystectomy was performed and the following day, two sets of blood culture were positive for gram-negative bacilli. Identification of C. somerae from the biochemical profile was difficult but possible by mass spectrometry and 16s rRNA sequence.