Prevalence and Antibiotic Susceptibility Trends of Selected Enterobacteriaceae, Enterococci, and Candida albicans in the Subgingival Microbiota of German Periodontitis Patients: A Retrospective Surveillance Study

Persistent enrichment of multidrug-resistant Klebsiella in oral and nasal communities during long-term starvation

BACKGROUND

The human oral and nasal cavities can act as reservoirs for opportunistic pathogens capable of causing acute infection. These microbes asymptomatically colonize the human oral and nasal cavities which facilitates transmission within human populations via the environment, and they routinely possess clinically significant antibiotic resistance genes. Among these opportunistic pathogens, the Klebsiella genus stands out as a notable example, with its members frequently linked to nosocomial infections and multidrug resistance. As with many colonizing opportunistic pathogens, the essential transmission factors influencing the spread of Klebsiella species among both healthy and diseased individuals remain unclear.

RESULTS

Here, we explored a possible explanation by investigating the ability of oral and nasal Klebsiella species to outcompete their native microbial community members under in vitro starvation conditions, which could be analogous to external hospital environments or the microenvironment of mechanical ventilators. When K. pneumoniae and K. aerogenes were present within a healthy human oral or nasal sample, the bacterial community composition shifted dramatically under starvation conditions and typically became enriched in Klebsiella species. Furthermore, introducing K. pneumoniae exogenously into a native microbial community lacking K. pneumoniae, even at low inoculum, led to repeated enrichment under starvation. Precise monitoring of K. pneumoniae within these communities undergoing starvation indicated rapid initial growth and prolonged viability compared to other members of the microbiome. K. pneumoniae strains isolated from healthy individuals' oral and nasal cavities also exhibited resistance to multiple classes of antibiotics and were genetically similar to clinical and gut isolates. In addition, we found that in the absence of Klebsiella species, other understudied opportunistic pathogens, such as Peptostreptococcus, increased in relative abundance under starvation conditions.

CONCLUSIONS

Our findings establish an environmental and microbiome community circumstance that allows for the enrichment of Klebsiella species and other opportunistic pathogens. Klebsiella's enrichment may hinge on its ability to quickly outgrow other members of the microbiome. The ability to outcompete other commensal bacteria and to persist under harsh environmental conditions could be an important factor that contributes to enhanced transmission in both commensal and pathogenic contexts. Video Abstract.

Biological characterization and complete genome analysis of the newly isolated Serratia liquefaciens phage vB_SlqS_ZDD2

A novel lytic phage named vB_SlqS_ZDD2 was isolated from hospital sewage using the double-layer agar method with Serratia liquefaciens ATCC 27592 as the host. BLASTn analysis showed that the genome sequence of phage vB_SlqS_ZDD2 did not resemble any other phages in the NCBI database. Phenotype and phylogeny analysis indicated that this phage might be a new member of the class Caudoviricetes. Phage vB_SlqS_ZDD2 has a dsDNA genome of 49,178 bp with 55% GC content and has 73 open reading frames. This phage exhibited strong lytic activity and a wide range of pH (3-12) and temperature tolerance (below 70℃).

Efficacy of perioperative oral care management in the prevention of surgical complications in 503 patients after pancreaticoduodenectomy for resectable malignant tumor: A multicenter retrospective analysis using propensity score matching

BACKGROUND

Pancreaticoduodenectomy has been associated with a high mortality rate and significant postoperative morbidity. Recently, perioperative oral care management has been reported to be effective in preventing postoperative pneumonia and surgical site infection. In this study, we examined the effect of perioperative oral care management in reducing complications after pancreaticoduodenectomy, including surgical site infection.

METHODS

This retrospective multicenter study included 503 patients who underwent pancreaticoduodenectomy at 8 facilities between January 2014 and December 2016. Among these, 144 received perioperative oral management by dentists and dental hygienists (oral management group), whereas the remaining 359 did not (control group). The oral care management program included oral health instructions, removal of dental calculus, professional mechanical tooth cleaning, removal of tongue coating, denture cleaning, instructions for gargling, and tooth extraction. The participants were matched using propensity scores to reduce background bias. Various factors were examined for correlation with the development of complications.

RESULTS

The incidence of organ/space surgical site infection was significantly lower in the oral management group than in the control group (8.0% vs 19.6%, P = .005). Multivariable logistic regression analysis revealed that hypertension and lack of perioperative oral management were independent risk factors for organ/space surgical site infection. Lack of perioperative oral management had an odds ratio of 2.847 (95% confidence interval 1.335-6.071, P = .007).

CONCLUSION

Perioperative oral care management reduces the occurrence of surgical site infections after pancreaticoduodenectomy and should be recommended as a strategy to prevent infections in addition to antibiotic use.

In Vitro Assessment of Antifungal and Antibiofilm Efficacy of Commercial Mouthwashes against Candida albicans

Candida albicans is the most critical fungus causing oral mycosis. Many mouthwashes contain antimicrobial substances, including antifungal agents. This study aimed to investigate the in vitro activity of 15 commercial mouthwashes against 12 strains of C. albicans. The minimal inhibitory concentrations (MICs), minimal fungicidal concentrations (MFCs), and anti-biofilm activity were studied. MICs were determined by the micro-dilution method using 96-well plates, and MFCs were determined by culturing MIC suspensions on Sabouraud dextrose agar. Anti-biofilm activity was evaluated using the crystal violet method. The mouthwashes containing octenidine dihydrochloride (OCT; mean MICs 0.09-0.1%), chlorhexidine digluconate (CHX; MIC 0.12%), and CHX with cetylpyridinium chloride (CPC; MIC 0.13%) exhibited the best activity against C. albicans. The active compound antifungal concentrations were 0.5-0.9 µg/mL for OCT products and 1.1-2.4 µg/mL for CHX rinses. For mouthwashes with CHX + CPC, concentrations were 1.56 µg/mL and 0.65 µg/mL, respectively. Products with polyaminopropyl biguanide (polyhexanide, PHMB; MIC 1.89%) or benzalkonium chloride (BAC; MIC 6.38%) also showed good anti-Candida action. In biofilm reduction studies, mouthwashes with OCT demonstrated the most substantial effect (47-51.1%). Products with CHX (32.1-41.7%), PHMB (38.6%), BAC (35.7%), Scutellaria extract (35.6%), and fluorides + essential oils (33.2%) exhibited moderate antibiofilm activity. The paper also provides an overview of the side effects of CHX, CPC, and OCT. Considering the in vitro activity against Candida albicans, it can be inferred that, clinically, mouthwashes containing OCT are likely to offer the highest effectiveness. Meanwhile, products containing CHX, PHMB, or BAC can be considered as promising alternatives.

Persistent enrichment of multidrug resistant Klebsiella in oral and nasal communities during long-term starvation

The human oral and nasal cavities can act as reservoirs for opportunistic pathogens capable of causing acute infection. These microbes asymptomatically colonize the human oral and nasal cavities which facilitates transmission within human populations via the environment, and they routinely possess a clinically-significant antibiotic-resistance genes. Among these opportunistic pathogens, the Klebsiella genus stands out as a notable example, with its members frequently linked to nosocomial infections and multidrug resistance. As with many colonizing opportunistic pathogens, how Klebsiella transitions from an asymptomatic colonizer to a pathogen remains unclear. Here, we explored a possible explanation by investigating the ability of oral and nasal Klebsiella to outcompete their native microbial community members under in vitro starvation conditions, which could be analogous to external hospital environments. When Klebsiella was present within a healthy human oral or nasal sample, the bacterial community composition shifted dramatically under starvation conditions and typically became dominated by Klebsiella. Furthermore, introducing K. pneumoniae exogenously into a native microbial community lacking K. pneumoniae, even at low inoculum, led to repeated dominance under starvation. K.pneumoniae strains isolated from healthy individuals' oral and nasal cavities also exhibited resistance to multiple classes of antibiotics and were genetically similar to clinical and gut isolates. In addition, we found that in the absence of Klebsiella, other understudied opportunistic pathogens, such as Peptostreptococcus, dominate under starvation conditions. Our findings establish an environmental circumstance that allows for the outgrowth of Klebsiella and other opportunistic pathogens. The ability to outcompete other commensal bacteria and to persist under harsh environmental conditions may contribute to the colonization-to-infection transition of these opportunistic pathogens.

Orbital fibrous capsule formation with abscess found 3 years after penetrating injury from a wooden chopstick

Intraorbital wooden foreign bodies are sometimes difficult to diagnose because of nonspecific clinical manifestations and diversity of imaging characteristics. We herein report a case involving a 72-year-old woman with a history of trauma induced by a coated wooden chopstick 3 years prior. Two years after the incident, computed tomography (CT) scan revealed an intraorbital mass that was initially diagnosed as an intraorbital hemangioma. The patient presented with hyperemia, impairment of ocular movement, and optic neuropathy in her right eye. Magnetic resonance imaging (MRI) showed granulation tissue and an abscess around a foreign body, which was compressing the eyeball. Surgical extraction of the foreign body was performed, leading to resolution of symptoms. The depiction of wooden foreign bodies by imaging is complicated and affected by several factors, increasing the risk of delayed diagnosis. To avoid permanent sequelae, MRI might be helpful because its imaging capabilities are superior to those of CT.

Prevalence of Enterococci and Vancomycin Resistance in the Throat of Non-Hospitalized Individuals Randomly Selected in Central Italy

Enterococci are commonly found in the environment and humans as a part of the normal microbiota. Among these, Enterococcus faecalis and Enterococcus faecium can convert into opportunistic pathogens, making them a major cause of nosocomial infections. The rapid diffusion of vancomycin-resistant strains and their impact on nosocomial settings is of considerable concern. Approximately one-third of the E. faecium infections in Italy are caused by vancomycin-resistant strains. This study explored the hypothesis that the oral cavity could represent a silent reservoir of virulent enterococci. A sample of 862 oral flora specimens collected from healthy human volunteers in Central Italy was investigated by real-time PCR to detect E. faecalis and E. faecium, as well as the genetic elements that most frequently determine vancomycin resistance. The prevalence of E. faecalis was 19%, a value that was not associated with alcohol consumption, tobacco smoking, or age of the subjects. Less frequently detected, with an overall prevalence of 0.7%, E. faecium was more common among people older than 49 years of age. The genes conferring vancomycin resistance were detected in only one sample. The results indicate that the oral cavity can be considered a reservoir of clinically relevant enterococci; however, our data suggest that healthy individuals rarely carry vancomycin-resistant strains.

Complications and treatment errors related to regenerative periodontal surgery

Regenerative periodontal surgical procedures are an important component in the treatment of advanced periodontitis. They aim to improve the long-term prognosis of teeth that are periodontally compromised by the presence of intrabony and/or furcation defects, resulting biologically in formation of root cementum, periodontal ligament, and alveolar bone and evidenced clinically by reduction of deep pockets to maintainable probing depths and/or improvements of vertical and horizontal furcation depth. Over the last 25 years, substantial clinical evidence has been accumulated to support the value of regenerative procedures in periodontally compromised dentitions. However, treatment success requires close attention to certain factors on the level of the patient, the tooth/defect, and the operator. Ignoring these factors in case selection, treatment planning, and treatment execution will increase the risk of complications that may jeopardize clinical success and may even be considered as treatment errors. Based on the currently available evidence from clinical practice guidelines, treatment algorithms, and on expert opinion, the present article provides an overview on the main factors, which influence the outcomes of regenerative periodontal surgery and gives recommendations on how to prevent complications and treatment errors.

Molecular Characterization and Epidemiology of Carbapenem-Resistant Enterobacteriaceae Isolated from Pediatric Patients in Guangzhou, Southern China

Background

Carbapenem-resistant Enterobacteriaceae (CRE) are spreading worldwide, posing a serious public health concern. However, the data on CRE strains that cause infections in children in Guangzhou remain limited. Therefore, this study aimed to investigate the epidemiology of CRE, drug resistance, and resistance mechanisms in children in Guangzhou, Southern China.

Methods

In total, 54 nonrepetitive CRE strains were collected in pediatric patients at three centers in Guangzhou, Southern China, from January 2016 to August 2018. CRE isolates were used for further studies on antimicrobial susceptibility, the modified Hodge test (MHT), the modified carbapenem inactivation method (mCIM), and drug resistance genes. Multilocus sequence typing (MLST) was used to elucidate the molecular epidemiology of K. pneumoniae.

Results

The isolated CRE strains include 34 K. pneumoniae (63.0%), 10 E. coli (18.5%), 4 Enterobacter cloacae (7.4%), and 6 Proteus mirabilis (11.1%) strains. The strains were isolated mainly from the blood (31.5%, n = 17), sputum (31.5%, n = 17), and urine (16.7%, n = 9). All CRE isolates were highly resistant to the third- or fourth-generation cephalosporins, carbapenems, and β-lactam + β-lactamase inhibitors (94.4%-96.3%). In addition, the resistance rates to amikacin, ciprofloxacin, levofloxacin, tigecycline, and colistin were 5.6%, 14.8%, 16.7%, 9.3%, and 0%, respectively. Carbapenemase was detected in 35 (64.8%) of the CRE isolates. The most dominant carbapenemase gene was bla _NDM (n = 17, 48.6%), followed by bla _IMP (n = 13, 37.1%) and bla _OXA-23 (n = 4, 11.4%). Other carbapenemase genes (bla _KPC, bla _sim, bla _Aim, bla _GES, bla _Gim, bla _OXA-2 , and bla _OXA-48 ) and the mcr-1 gene were not detected. MLST analysis showed high diversity among the K. pneumoniae, and ST45 (11.7%, 4/34) was the dominant sequence type.

Conclusion

This study revealed bla _NDM was the most dominant carbapenemase gene in children in Guangzhou. Infection control measures need to be taken for the prevention and treatment of CRE infections.

Trends and Correlation Between Antimicrobial Resistance and Antibiotics Consumption in a Specialist Children’s Hospital from 2016 to 2021

Purpose

To explore the trends and correlation between antibiotics consumption and antimicrobial resistance in children in a specialist hospital from 2016–2021 in China.

Patients and Methods

This retrospective study investigated data on the consumption of antibiotics and antimicrobial resistance in children. Antibiotics consumption was expressed as defined daily doses (DDDs)/1000 patient-days based on the Guidelines for Anatomical Therapeutic Chemical. The trends in antibiotics consumption and antimicrobial resistance rates were analyzed by linear regression, while Spearman correlation analysis was employed to evaluate their correlations.

Results

An increasing trend in the annual consumption of carbapenems and monobactams was detected (all P<0.05). A significant upward trend was detected in the annual resistance rates of Enterococcus faecium to ciprofloxacin, Streptococcus pneumonia to ceftriaxone, Acinetobacter baumannii to carbapenems, Enterobacter cloacae to carbapenems, Pseudomonas aeruginosa to ceftazidime, and Escherichia coli to cefepime, while the annual resistance rates of Escherichia coli to carbapenems had a significant downward trend (all P<0.05). The consumption of cephalosporin/β-lactamase inhibitor (C/BLI) combinations and carbapenems had significant positive correlations with the resistance rates of Acinetobacter baumannii to carbapenems (r=0.763, P<0.001; r=0.806, P<0.001), Enterobacter cloacae to carbapenems (r=0.675, P<0.001; r=0.417, P=0.043), and Pseudomonas aeruginosa to ceftazidime (r=0.625, P=0.001; r=0.753, P<0.001), respectively. Also, increasing consumption of monobactams was related to the upward resistance rates of Acinetobacter baumannii to carbapenems (r=0.557, P=0.005) and Enterobacter cloacae to carbapenems (r=0.507, P= 0.011).

Conclusion

This study demonstrated significant positive associations between antibiotics consumption and specific antimicrobial resistance rates. The current findings pointed out some directions to pursue in controlling the prevalence of certain resistant bacterial strains in children.

Ecological Effects of Daily Antiseptic Treatment on Microbial Composition of Saliva-Grown Microcosm Biofilms and Selection of Resistant Phenotypes

Antiseptics are widely used in dental practice and included in numerous over-the-counter oral care products. However, the effects of routine antiseptic use on microbial composition of oral biofilms and on the emergence of resistant phenotypes remain unclear. Microcosm biofilms were inoculated from saliva samples of four donors and cultured in the Amsterdam Active Attachment biofilm model for 3 days. Then, they were treated two times daily with chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) for a period of 7 days. Ecological changes upon these multiple antiseptic treatments were evaluated by semiconductor-based sequencing of bacterial 16S rRNA genes and identification of amplicon sequence variants (ASVs). Furthermore, culture-based approaches were used for colony-forming units (CFU) assay, identification of antiseptic-resistant phenotypes using an agar dilution method, and evaluation of their antibiotic susceptibilities. Both CHX and CPC showed only slight effects on CFU and could not inhibit biofilm growth despite the two times daily treatment for 7 days. Both antiseptics showed significant ecological effects on the microbial compositions of the surviving microbiota, whereby CHX led to enrichment of rather caries-associated saccharolytic taxa and CPC led to enrichment of rather gingivitis-associated proteolytic taxa. Antiseptic-resistant phenotypes were isolated on antiseptic-containing agar plates, which also exhibited phenotypic resistance to various antibiotics. Our results highlight the need for further research into potential detrimental effects of antiseptics on the microbial composition of oral biofilms and on the spread of antimicrobial resistance in the context of their frequent use in oral healthcare.