Multicenter Investigation of Drug-Resistance in Burkholderia Cepacia Bloodstream Infections in Hebei Province, China, from 2016 to 2021.

Objective: To compare the epidemiological characteristics and drug resistance of Burkholderia cepacia isolated from blood cultures, and to provide data support and a scientific basis for the clinical treatment and detection of hospital infections. Methods: The Hebei Province Antimicrobial Surveillance Network received 349 B. cepacia strains isolated from blood cultures reported by 83 hospitals, from 2016 to 2021. These strains were identified by MALDI-TOF MS and, the antibiotic sensitivity tests were carried out using the VITEK 2 COMPACT system. The 2023 Institute of Clinical and Laboratory Standardization drug-susceptibility breakpoints were used for drug susceptibility testing and the data were analyzed using WHONET5.6 software. Results: A total of 349 B. cepacia strains were isolated from 2016 to 2021, including 68 strains from secondary hospitals and 281 strains from tertiary hospitals. The ratios of male: female patients with B. cepacia bloodstream infections in all hospitals, secondary hospitals, and tertiary hospitals were 1.49:1 (209/140), 2.09:1 (46/22), and 1.38:1 (163/118), respectively. Most B. cepacia strains were isolated in intensive care units (ICUs), followed by internal medicine departments, accounting for 49.57% (173/349) and 22.92% (80/349), respectively. Regarding the age distribution, most patients were elderly (>65 years, 57.59%, 201/349), with numbers of patients gradually declining with decreasing of age. The resistance rates for levofloxacin, ceftazidime, and sulfamethoxazole decreased over the 6-year period (P<0.05), while there were no significant changes in the resistance rates for meropenem, chloramphenicol, and minocycline (P>0.05). There was no significant difference in drug-resistance rates between secondary and tertiary hospitals (P>0.05). Conclusion: Attention should be paid to bloodstream infections caused by B. cepacia, especially elderly patients and patients admitted to the ICU. The difficult treatment characteristics of B. cepacia bloodstream infections mean that laboratories and clinicians should pay careful attention to drug resistance to provide a basis for their prevention and empirical treatment.

Seasonal meropenem resistance in Acinetobacter baumannii and influence of temperature-driven adaptation.

BACKGROUND: Recognition of seasonal trends in bacterial infection and drug resistance rates may enhance diagnosis, direct therapeutic strategies, and inform preventive measures. Limited data exist on the seasonal variability of Acinetobacter baumannii. We investigated the seasonality of A. baumannii, the correlation between temperature and meropenem resistance, and the impact of temperature on this bacterium. RESULTS: Meropenem resistance rates increased with lower temperatures, peaking in winter/colder months. Nonresistant strain detection exhibited temperature-dependent seasonality, rising in summer/warmer months and declining in winter/colder months. In contrast, resistant strains showed no seasonality. Variations in meropenem-resistant and nonresistant bacterial resilience to temperature changes were observed. Nonresistant strains displayed growth advantages at temperatures ≥ 25 °C, whereas meropenem-resistant A. baumannii with ß-lactamase OXA-23 exhibited greater resistance to low-temperature (4 °C) stress. Furthermore, at 4 °C, A. baumannii upregulated carbapenem resistance-related genes (adeJ, oxa-51, and oxa-23) and increased meropenem stress tolerance. CONCLUSIONS: Meropenem resistance rates in A. baumannii display seasonality and are negatively correlated with local temperature, with rates peaking in winter, possibly linked to the differential adaptation of resistant and nonresistant isolates to temperature fluctuations. Furthermore, due to significant resistance rate variations between quarters, compiling monthly or quarterly reports might enhance comprehension of antibiotic resistance trends. Consequently, this could assist in formulating strategies to control and prevent resistance within healthcare facilities.

Retrospective Analysis of Sensitivity Characteristics of Enterobacteriaceae: A Study Based on Specimen Types, Sex, and Age Bracket of Patients.

Objective: Enterobacteriaceae have displayed widespread trends of antimicrobial resistance in recent years. Therefore, we aimed to analyse the antimicrobial susceptibility of common bacteria and explore the significance in treatment and research of infections induced by Enterobacteriaceae. Methods: We retrospectively analysed 10,775 antimicrobial susceptibility test results acquired over a 6-year period in the affiliated hospital of Chengde Medical University. We divided the data based on specimen type (blood, sputum, pus, or urine), and population characteristics (age bracket and sex) for analysis. We mainly analysed the antimicrobial susceptibility of Escherichia coli (Eco), Klebsiella pneumoniae (Kpn), and Enterobacter cloacae (Ecl). Results: In our study, it was found that the resistance rates of Eco, Kpn, and Ecl to most antimicrobial agents were significantly different (P < 0.05) on specimen type and age bracket. The Eco from sputum had the highest resistance rates except ciprofloxacin (CIP), levofloxacin (LVX), and gentamicin (GEN); the Kpn from urine had the highest resistance rates to all antimicrobial agents; the Ecl from urine had the highest resistance rates to most antimicrobial agents. The Eco from geriatric patients had the highest resistance rates except GEN and SXT; the Kpn from adult patients had the lowest resistance rates to most antimicrobial agents except LVX. The Eco isolated from males had higher resistance rates to most antimicrobial agents except CIP, LVX, and NIT than those isolated from females; the Kpn showed significant differences in antimicrobial susceptibility to only 5 out of 22 antimicrobial agents (P < 0.05); the Ecl showed significant differences in susceptibility only to two antimicrobial agents, LVX and TOB (P < 0.01). Conclusion: The antimicrobial susceptibility of Enterobacteriaceae was significantly different among specimen type, age bracket and sex of patients, which is of great significance for the treatment and research of infection.

Clinical characteristics, susceptibility profiles, and treatment of nocardiosis: a multicenter retrospective study in 2015-2021.

OBJECTIVES: This study aimed to investigate the microbiological characteristics, antimicrobial resistance profiles, antibiotic choice, and outcomes of Nocardia infection in various centers over a 7-year period (from 2015 to 2021). METHODS: We retrospectively analyzed the medical records of all hospitalized patients diagnosed with Nocardia between 2015 and 2021. The isolates were identified to the species level through the sequencing of 16S ribosomal RNA or secA1 or ropB genes. The susceptibility profiles were determined using the broth microdilution method. RESULTS: Of the 130 nocardiosis cases, 99 (76.2%) were established as pulmonary infection, of which the most common underlying disease was chronic lung disease (40.4%, 40/99), including bronchiectasis, chronic obstructive pulmonary disease, and chronic bronchitis. Among 130 isolates, 12 species were identified, with the most common species being Nocardia cyriacigeorgica (37.7%) and Nocardia farcinica (20.8%). All Nocardia strains were susceptible to linezolid and amikacin, and the susceptibility rate of trimethoprim-sulfamethoxazole (TMP-SMX) was 97.7%. Of the 130 patients, 86 (66.2%) received TMP-SMX monotherapy or multidrug regimen. Furthermore, 92.3% patients who were treated achieved clinical improvement. CONCLUSION: TMP-SMX was the treatment of choice for nocardiosis, and other combination drugs with TMP-SMX therapy yielded even better results.

Bacteria can drill holes: Salmonella enterica serovar London infection of the leg and heel with colonization of the gut.

Salmonella enterica serovar London is known to colonize the human digestive tract and can cause gastroenteritis and diarrhea. The excretion of S. London in the stool can spread into the environment. However, S. London colonization of the gut is not known to cause infection of the soft tissues. Here, we report a case of S. London infection of the skin and soft tissue of the leg and heel.

Drug resistance analysis of Enterobacter cloacae isolated from blood samples in Hebei, 2016-2021 / 中国热带医学

@# Objective　To investigate the drug resistance of Enterobacter cloacae isolated from blood samples in 75 member units of the Bacterial Drug Resistance Monitoring Network in Hebei, 2016- 2021, so as to provide a basis for rational drug use in clinic. Methods　WHONET 5.6 software was used to retrospectively analyze drug susceptibility of Enterobacter cloacae isolated from 32 secondary hospitals and 43 tertiary hospitals. SPSS19.0 software was used for statistical analysis. Results After removing the duplicate strains, 1 225 strains of E. cloacae were isolated from blood samples of 75 hospitals during 6 years, including 157 strains from secondary hospitals and 1 068 strains from tertiary hospitals. In this study, the resistance of Enterobacter cloacae to 16 kinds of antibiotics was analyzed. The drug resistance rates to cefuroxime (52.4%-67.8%), piperacillin (27.4%-31.2%), ceftazidime (27.8%-35.5%), ceftriaxone (29.5%-45.0%), aztreonam (22.2%-32.3%), cotrimoxazole (21.6%-28.7%) were higher; the resistance rates to amikacin and tobramycin were lower than 15.0%. The resistance rates to imipenem and meropenem were 3.6%-12.3% and 5.1%-11.4%, respectively. The resistance rate to ciprofloxacin in tertiary hospitals was 22.4%, and the resistance rate to cotrimoxazole was 23.9%. Except for these two antimicrobials, the resistance rates to other antimicrobial drugs in tertiary hospitals were higher than that in secondary hospitals. A total of 121 carbapenem-resistant Enterobacter cloacae strains were detected in the past 6 years, with an increasing detection rate (χ2trend=6.305, P=0.012). Conclusions　Enterobacter cloacae has great differences in antimicrobial resistance to different antibiotics, and is sensitive to carbapenems. The drug resistance in tertiary hospitals is generally higher than that in secondary hospitals. Drug resistance monitoring and drug resistance mechanism research should be strengthened to better guide clinical drug use and curb the rise of drug resistance.

A case of Aspergillus salwaensis-induced spinal infection / 中国热带医学

@#Abstract: To report a case of Aspergillus salwaensis-induced spinal infection and its laboratory detection. The inflammatory granulation and necrotic tissue samples of a patient with spinal infection were collected from, the Affiliated Hospital of Chengde Medical College on June 17, 2020 for direct smear microscopy and culture, and the isolated strain was identified by microscopy by smear staining, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS), molecular identification and in vitro antifungal susceptibility test. The patient was 62 years old female and presented with recurrent chest and back pain with no obvious cause. The initial diagnosis was spinal infection, after 7 days of treatment with levofloxacin, the effect was not good. Surgery was then performed remove the lesion via posterior thoracic debridement, and fungal hypha was observed under microscope in tissue specimens. The isolated strains had no typical structure, MALDI-TOF-MS was used for identification for many times, but there was no identification result. After 7 days of fluconazole treatment, the patient's condition improved, and her chest and back pain were alleviated compared to before surgery. The patient was discharged and followed up in the outpatient department, the fungus was later identified as Aspergillus salwaensis by sequence analysis of the internal transcribed spacer (ITS) gene sequencing, and the patient's antifungal medication was changed to voriconazole after with the attending physician. The patient consciously recovered well with no pain in the operative area and normal spinal activity at 1 year follow-up. The possibility of spinal fungal infection should be considered in patients with back pain without a clear cause and poor response to routine antibiotic treatment. Direct smear report of microscopic results are very important for guiding clinical antibiotic selection for rare filament fungi with atypical colony and microscopic morphology and unsuccessful MALDI-TOF-MS identification, molecular biological methods such as ITS sequence analysis can be helpful for early identification of the fungal species, improving identification speed.

A Case of Meningitis in an Infant Due to Hypervirulent Klebsiella pneumoniae Transmission Within a Family.

Hypervirulent Klebsiella pneumoniae (hvKP), an emerging pathotype derived from K. pneumoniae, frequently causes invasive infections of multiple organs and is associated with both high disability and fatality rates. In this study, a case of meningitis in a young infant caused by hvKP is presented. Cytological and biochemical examinations of the cerebrospinal fluid (CSF) revealed purulent meningitis, a diagnosis that was confirmed by a positive CSF culture result. The pathogen was identified as hvKP through analysis of positive virulence-associated genes. Meanwhile, hvKP was also isolated from stool samples of both the infant and her father. Antimicrobial susceptibility, capsular typing, and multilocus sequence typing (MLST) of three isolates from the infant's CSF and stool and her father's stool samples were analyzed. The three K. pneumoniae isolates were susceptible to all antibiotics except ampicillin and were identified as capsular serotype K2 and sequence type 86. These genetic relatedness analyses indicated that the strain isolated from the infant's CSF might have originated from her father's stool via familial transmission. This case is the first report of meningitis in an infant due to hvKP transmitted within a family.

Effects of Blood Culture Aerobic/Anaerobic Bottle Collection Patterns from Both Sides of the Body on Positive Blood Culture Rate and Time-to-Positivity.

Background: Although the principles for blood cultures (BCs) guidelines provide a recommendation for collection patterns, the complexity of clinical practice occasionally prompts clinicians to adopt non-standard collection patterns. Here, we investigate the influences of different BC collection patterns on detection of pathogens. Methods: The BC collection patterns of 96 hospitals were surveyed online. And a retrospective study of BC data from a tertiary hospital was conducted. Results: The results showed that 53.1% of hospitals adopted the recommended patterns. Among the 1439 episodes of true-positive BCs, 67.4% were found in both the left- and right-sided bottles; 58.2% were found in both aerobic and anaerobic bottles. Conclusion: The present study suggested that the rate of standard collection patterns of blood culture was low and the non-standard collection patterns were associated with decreased detection of pathogens. Simultaneous collection of blood on the left and right sides was recommended as an effective pattern of BC collection.

Direct Identification, Antimicrobial Susceptibility Testing, and Extended-Spectrum ß-Lactamase and Carbapenemase Detection in Gram-Negative Bacteria Isolated from Blood Cultures.

Purpose: To shorten the turnaround time for blood culture (BC) analyses, a rapid method was developed for the direct identification, antimicrobial susceptibility testing (AST), and multidrug resistance testing of bacteria-positive BCs. Materials and Methods: The mixtures in BC bottles were treated with the multistep centrifugation method developed here and the conventional culture-based method. The bacterial sediment obtained after centrifugation was analyzed directly with MALDI-TOF MS and Vitek 2 Compact, and AST was performed directly with the Kirby-Bauer (K-B) disk diffusion, VITEK 2 Compact, and E-test methods. Extended spectrum lactamases (ESBLs) were detected with discs containing cefotaxime, cefotaxime/clavulanate, ceftazidime, and ceftazidime/clavulanate, and carbapenemase was detected with the modified carbapenem inactivation method (mCIM) and EDTA-mCIM (eCIM). Results: All the results of direct testing were compared to those of the conventional methods, to evaluate the accuracy of the direct methods. The accuracies of the direct Vitek 2 Compact and MALDI-TOF MS methods were 95.5% (214/224) and 90.2% (202/224), respectively. Direct AST with K-B, Vitek 2, and E-test showed category agreement of 96.0% (2611/2721), 96.1% (2614/2721), and 97.4% (2650/2721), respectively, and the major errors and very major errors were < 2% for all three methods. In the direct determination of ESBLs, the results for cefotaxime combined with cefotaxime/clavulanate were completely consistent with those after the standard isolation method. The carbapenemase detection rate with direct mCIM and eCIM was exactly the same as that with the standard method. Conclusion: These direct procedures based on multistep centrifugation are not only highly accurate but are appropriate for clinical laboratory use because the turnaround time is shorter.

Developing Two Rapid Protein Extraction Methods Using Focused-Ultrasonication and Zirconia-Silica Beads for Filamentous Fungi Identification by MALDI-TOF MS.

Filamentous fungi identification by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been challenging due to the lack of simple and rapid protein extraction methods and insufficient species coverage in the database. In this study, we created two rapid protein extraction methods for filamentous fungi: a one-step zirconia-silica beads method (ZSB) and a focused-ultrasonication method (FUS). The identification accuracy of two methods were evaluated with the VITEK MS, as well as number of spectra peaks and signal-to-noise ratio (S/N) with M-Discover 100 MALDI-TOF MS compared to the routine method. The better method was applied to build a filamentous fungi in-house spectra library for the M-Discover 100 MS, and then another one and routine method were performed in parallel to verify the accuracy and commonality of the in-house library. Using the two optimized methods, the dedicated operating time before MALDI-TOF MS analysis was reduced from 30 min to 7 (ZSB) or 5 (FUS) min per sample, with only a few seconds added for each additional strain. And both two methods identified isolates from most mold types equal to or better than the routine method, and the total correct identification rate using VITEK MS was 79.67, 76.42, and 76.42%, respectively. On the other hand, the two rapid methods generally achieved higher maximum and minimum S/N ratios with these isolates tested as compared to the routine method. Besides, the ZSB method produced overall mean of maximum and minimum S/N ratio higher than that by FUS. An in-house library of M-Discover MS was successfully built from 135 isolates from 42 species belonging to 18 genera using the ZSB method. Analysis of 467 isolates resulted in 97.22% correctly identified isolates to the species level by the ZSB method versus 95.50% by the routine method. The two novel methods are time- and cost-effective and allow efficient identification of filamentous fungi while providing a simplified procedure to build an in-house library. Thus, more clinical laboratories may consider adopting MALDI-TOF MS for filamentous fungi identification in the future.

Epidemiology of Carbapenem-Resistant Enterobacteriaceae Infections: Report from the China CRE Network.

Carbapenem-resistant Enterobacteriaceae (CRE) infection is highly endemic in China, but estimates of the infection burden are lacking. We established the incidence of CRE infection from a multicenter study that covered 25 tertiary hospitals in 14 provinces. CRE cases defined as carbapenem-nonsusceptible Citrobacter freundii, Escherichia coli, Enterobacter cloacae, or Klebsiella pneumoniae infections during January to December 2015 were collected and reviewed from medical records. Antimicrobial susceptibility testing and carbapenemase gene identification were performed. Among 664 CRE cases, most were caused by K. pneumoniae (73.9%), followed by E. coli (16.6%) and E. cloacae (7.1%). The overall CRE infection incidence per 10,000 discharges was 4.0 and differed significantly by region, with the highest in Jiangsu (14.97) and the lowest in Qinghai (0.34). Underlying comorbidities were found in 83.8% of patients; the median patient age was 62 years (range, 45 to 74 years), and 450 (67.8%) patients were male. Lower respiratory tract infections (65.4%) were the most common, followed by urinary tract infection (16.6%), intra-abdominal infection (7.7%), and bacteremia (7.7%). The overall hospital mortality rate was 33.5%. All isolates showed nonsusceptibility to carbapenems and cephalosporins. The susceptibility rate of polymyxin B was >90%. Tigecycline demonstrated a higher susceptibility rate against E. coli than against K. pneumoniae (90.9% versus 40.2%). Of 155 clinical isolates analyzed, 89% produced carbapenemases, with a majority of isolates producing KPC (50%) or NDM (33.5%)-type beta-lactamases among K. pneumoniae and E. coli The incidence of CRE infection in China was 4.0 per 10,000 discharges. The patient-based disease burden in tertiary hospitals in China is severe, suggesting an urgent need to enhance infection control.