Antimicrobial ability and mechanism analysis of Lactobacillus species against carbapenemase-producing Enterobacteriaceae

BACKGROUND

This study aims to investigate the antimicrobial ability and mechanism analysis of Lactobacillus species against carbapenemase-producing Enterobacteriaceae (CPE).

METHODS

Five Lactobacillus spp. strains and 18 CPE clinical isolates were collected. Their anti-CPE effects were assessed by agar well diffusion and broth microdilution assay, as well as time-kill test. Finally, the specific anti-CPE mechanism, especially for the effect of organic acids was determined using broth microdilution method.

RESULTS

All of five Lactobacilli isolates displayed the potent activity against most CPE isolates with mean zones of inhibition ranging 10.2-21.1 mm. The anti-CPE activity was not affected by heating, catalase, and proteinase treatment. Under the concentration of 50% LUC0180 cell-free supernatant (CFS), lactic acid, and mix acid could totally inhibit the growth of carbapenem-resistant Klebsiella pneumoniae (CPE0011), and acetic acid could inhibit 67.8%. In contrast, succinic acid and citric acid could not inhibit the growth of CPE0011. While we decreased the concentration to 25%, only lactic acid and mix acid displayed 100% inhibition. In contrast, succinic acid, citric acid and acetic acid did not show any inhibitory effect.

CONCLUSIONS

Lactobacillus strains exhibit potent anti-CPE activity, and lactic acid produced by Lactobacillus strains is the major antimicrobial mechanism.

Reduced economic burden of AIDS-defining illnesses associated with adherence to antiretroviral therapy

OBJECTIVES

We assessed the economic burden of AIDS-defining illnesses (ADIs), which was further stratified by adherence to antiretroviral therapy (ART).

METHODS AND MATERIALS

A nationwide longitudinal cohort of 18,234 incident cases with HIV followed for 11years was utilized. Adherence to ART was measured by medication possession ratio (MPR). Generalized estimating equations modeling was used to estimate the cost impact of ADIs.

RESULTS

Having opportunistic infections increased the annual cost by 9% (varicella-zoster virus infection) to 98% (cytomegalovirus disease), while the annual costs increased by 26% (Kaposi's sarcoma) to 95% (non-Hodgkin's lymphoma) in the year when AIDS-related cancer occurred. ADIs occurred more frequently in the years with low adherence for ART compared to the high-adherence years (e.g., 0.1≤MPR<0.8 vs. MPR≥0.8, event rate of cytomegalovirus disease 4.03% vs. 0.51%). The annual baseline costs in the years with MPR<0.1, 0.1≤MPR<0.8, and MPR≥0.8 were $250, $4,752, and $8,990 (in 2018 USD), respectively. The economic impact of ADIs in the years with low adherence (MPR<0.1) was larger than that in the high-adherence years (MPR≥0.8) (e.g., MPR<0.1 vs. MPR≥0.8, annual cost increased by 244% vs. 9% when candidiasis occurred).

CONCLUSIONS

Adherence to ART may increase the baseline medical costs but mitigate the incidence and economic burden of ADIs.

Antimicrobial Activity of Lactobacillus Species Against Carbapenem-Resistant Enterobacteriaceae

Objective

This study aims to identify suitable lactobacilli that have anti-carbapenem-resistant Enterobacteriaceae (CRE) activity with in vitro tolerance to pepsin and bile salts.

Methods

Fifty-seven Lactobacillus spp. strains encompassing nine species were collected for investigation. Their viabilities in the presence of pepsin and bile salts were tested using tolerance tests. Their anti-CRE effects were assessed by agar well diffusion and broth microdilution assay, as well as time-kill test.

Results

Of the 57 Lactobacillus isolates collected, 31 had a less than 2-log reduction in their viability in both pepsin and bile salt tolerance tests. Of these 31 isolates, 5 (LUC0180, LUC0219, LYC0289, LYC0413, and LYC1031) displayed the greatest anti-CRE activity with a CRE zone of inhibition greater than 15 mm in agar well diffusion assays. The minimal inhibitory percentages of supernatants from these five strains against CREs ranged from 10 to 30%. With the exception of LUC0180, which had a minimal bactericidal percentage ≥ 40%, the bactericidal percentage of all the strains ranged from 20 to 40%. The inhibitory effect of the cell-free culture supernatants from these Lactobacillus strains did not change after heating but was abolished as the pH changed to 7.0. After a 24-h incubation, five of the Lactobacillus strains at a concentration of 10⁸ CFU/ml totally inhibited the growth of carbapenem-resistant Escherichia coli (CRE316) and Klebsiella pneumoniae (CRE632). After a 48-h incubation, the growth of CRE316 was completely inhibited under each concentration of lactobacilli based on time-kill test. Furthermore, when the concentration of lactobacilli was at 10⁸ CFU/ml, the decline in pH was faster than at other concentrations.

Conclusion

Some Lactobacillus strains exhibit anti-CRE activity, which suggests potential applications for controlling or preventing CRE colonization or infection.

Simultaneous three Enterobacteriaceae with different bla NDM-1-encoding plasmids in a patient transferred from mainland China to Taiwan

New-Delhi metallo-β-lactamase1 (NDM-1) Enterobacteriaceae are increasing worldwide. Herein, we describe a single patient who carried three unusual NDM-1 carbapenem-resistant Enterobacteriaceae – Enterobacter cloacae (E. cloacae) yielded from a urine specimen and Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) from stool specimens. For E. cloacae, its bla NDM-1-encoding plasmid was pKP04NDM with a size of ~54 kb replicons with an IncN backbone. For K. pneumoniae, its bla_NDM-1-encoding plasmid was pNDM-BTR with a size of ~59.6 kb and belonged to IncN. For E. coli, its main bla_NDM-1-encoding plasmid was pIMP-HK1500, and the NDM-1 gene was obtained from a part of pNDM-BTR (8439 bp). These three clinical strains are reported for the first time and are assumed to be imported from mainland China to Taiwan. The three different plasmids were never reported in K. pneumoniae, E. coli, and Citrobacter spp before. Owing to their associated multidrug resistance, appropriate measures of periodic, targeted surveillance, and development of new antimicrobial agents are urgently needed.

Diagnosis and impact of neuropathic pain in leprosy patients in Nepal after completion of multidrug therapy

Objectives

Neuropathic pain (NP) can occur as a chronic complication of leprosy neuropathy. NP epidemiology and its impact on patients have not been well documented. This study investigates NP prevalence and impact in the years after patients are declared “released from treatment” (RFT) following multidrug therapy (MDT) completion.

Methods

In this cross-sectional study, 85 RFT patients were recruited within leprosy referral services in Nepal. The Douleur Neuropathique 4 Questionnaire (DN4) was used to screen for NP. Pain severity, impacts on patients’ daily activities and mental health were measured by using the Brief Pain Inventory (BPI), Screening of Activity Limitation and Safety Awareness (SALSA), and General Health Questionnaire-12 (GHQ-12) respectively.

Results

96% surveyed had been treated for multibacillary leprosy. 44 (52%) complained of pain of which 30 (68%) were diagnosed with NP. NP was not associated with age, gender, or presence of skin lesions or nerve symptoms at leprosy diagnosis. 70% of patients with NP had either history of or ongoing reactions and 47% had grade 2 disability. Nerve tenderness (p = 0.023) and current reactions (p = 0.018) were significant risk factors for NP. Patients with NP suffered significantly higher intensity pain (p = 0.023) and daily life interference (p = 0.003) and were more likely to have moderate to extreme daily activity limitations (p = 0.005). 13 (43%) exhibited psychological distress, and medications only reduced moderate degree (50–60%) of pain.

Conclusions

In our study, 35% of RFT patients had ongoing NP. Risk factors include nerve tenderness and reaction. They suffer from more daily life interference and psychological distress. Leprosy patient care should include recognition and management of NP.

Leprosy could present with chronic neuropathic pain, which might severely disturb daily life and mental health of leprosy-infected patients. This complication could also occur even years after antibiotics therapy completion, and we noticed that it is associated with recent leprosy reactions and nerve tenderness on physical examination. This is the first study that describes the epidemiology of neuropathic pain in leprosy patients in Nepal. More than one-third of leprosy patients who had completed multidrug therapy, are still suffering from neuropathic pain, and this study demonstrated that it has caused a great impact to their daily activities and psychological status. Therefore, prompt recognition and management of neuropathic pain are mandatory while taking care of the patients with leprosy.

In vitro and in vivo antibacterial activity of tigecycline against Vibrio vulnificus

BACKGROUND/PURPOSE

The aim of this study is to investigate the role of tigecycline in Vibrio vulnificus infection.

METHODS

Eight randomly selected clinical V. vulnificus isolates were studied to obtain the minimal inhibitory concentrations (MICs) of minocycline, cefotaxime, and tigecycline, and the time-kill curves of tigecycline alone or in combination with other drugs. A peritonitis mouse model was used for the evaluation of the therapeutic efficacy of tigecycline alone or cefotaxime in combination with minocycline or tigecycline.

RESULTS

The MIC of minocycline, cefotaxime, and tigecycline for eight clinical V. vulnificus isolates was 0.06-0.12 μg/mL, 0.03-0.06 μg/mL, and 0.03-0.06 μg/mL, respectively. In time-killing studies, at the concentration of 1 × MIC, the inhibitory effect of tigecycline persisted for 24 hours in five of eight isolates. With 2 × MIC and trough level, the inhibitory effect was noted in all isolates for 24 hours. With the combination of minocycline plus cefotaxime and tigecycline plus cefotaxime at 1/2 × MIC, the bactericidal effect was noted in 25% and 62.5% of eight isolates and synergism in 50% and 75% of isolates. With a low (1.25 × 10⁵ CFU/mL) inoculum, all infected mice survived with tigecycline alone, tigecycline plus cefotaxime, or minocycline plus cefotaxime on the 14^th day. At the inoculum of 1.25 × 10⁶ CFU, the survival rate was 33.3% on the 14^th day in the tigecycline plus cefotaxime-treated group, but none of the mice treated by tigecycline alone or minocycline plus cefotaxime survived (33.3% vs. 0%, p = 0.01 by Fisher's exact test).

CONCLUSION

Our in vitro combination and animal studies indicate that tigecycline could be an option for the treatment of invasive V. vulnificus infections.

Electrochemical detection of single micelles through 'nano-impacts'

A new class of 'soft' particles, micelles, is detected electrochemically via 'nano-impacts' for the first time. Short, sharp bursts of current are used to indicate the electrical contact of a single CTAB (cetyltrimethylammonium bromide) micelle with an electrode via the oxidation of the bromide content. The variation in CTAB concentration for such 'nano-impact' experiments shows that a significant number of 'spikes' are observed above the CMC (critical micelle concentration) and this is attributed to the formation of micelles. A comparison with dynamic light scattering is also reported.

Epidemiology and antimicrobial susceptibility profiles of Gram-negative bacteria causing urinary tract infections in the Asia-Pacific region: 2009-2010 results from the Study for Monitoring Antimicrobial Resistance Trends (SMART)

In 2009, the Study for Monitoring Antimicrobial Resistance Trends (SMART) was expanded to include surveillance of Gram-negative pathogens causing urinary tract infections (UTIs) in the Asia-Pacific region. A total of 1762 isolates were collected from 38 centers in 11 countries from patients with UTIs in 2009 and 2010. In vitro susceptibilities were determined by the broth microdilution method and susceptibility profiles were determined using minimum inhibitory concentration (MIC) interpretive criteria, as recommended by the Clinical and Laboratory Standards Institute (CLSI) in 2010 (M100-S20), in 2011 (M100-S21), and in 2012 (M100-S22). Enterobacteriaceae comprised 86.0% of the isolates, of which Escherichia coli (56.5%) and Klebsiella pneumoniae (13.8%) were the two most common species. Amikacin was the most effective antibiotic (91.7%), followed by ertapenem (86.9%), imipenem (86.6%), and piperacillin-tazobactam (84.9%). Rates of susceptibility were 50.3% for cefoxitin and ranged from 50.3% to 74.2% for the third- and fourth-generation cephalosporins. For ciprofloxacin and levofloxacin, the susceptibility rates were 51.4% and 54.4%, respectively. Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae comprised 28.2% of all isolates. We also found a high rate of resistance to carbapenems among Acinetobacter baumannii and Pseudomonas aeruginosa causing UTI. Interestingly, according to 2012 CLSI breakpoints, approximately 33.4% of ESBL producers were still susceptible to ceftazidime. However, this in vitro efficacy of ceftazidime needs to be validated in vivo by clinical data. The lowered CLSI interpretive breakpoints for piperacillin-tazobactam, carbapenems, and some cephalosporins in 2011-2012 for Enterobacteriaceae resulted in an approximate 5% drop in susceptibility rates for each drug, with the exception of imipenem for which the susceptibility rate dropped from 99.4% according to 2010 criteria to 91.2% according to 2011 criteria. With the updated CLSI criteria, the antimicrobial resistance threat from UTI pathogens in the Asia Pacific area was revealed to be more prominent.

Antimicrobial susceptibility profiles of Gram-negative bacilli isolated from patients with hepatobiliary infections in Taiwan: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART), 2006-2010

We investigated the trends in antimicrobial resistance among species of Gram-negative bacilli isolated from patients with hepatobiliary tract infections in Taiwan during the period 2006-2010 as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART). During the study period, 1032 isolates of Gram-negative bacilli that had been collected from patients with hepatobiliary infections were tested for susceptibility to 12 antimicrobial agents in accordance with the Clinical and Laboratory Standards Institute guidelines. Enterobacteriaceae accounted for the majority (n = 874, 84.7%) of isolates and Escherichia coli was the most common pathogen (n = 323, 31.3%). There were significantly more E. coli (P = 0.001) and Proteus mirabilis (P = 0.031) isolates collected from patients who had been hospitalized for less than 48 h and significantly more Serratia marcescens (P = 0.035) and Pseudomonas aeruginosa (P = 0.008) isolates collected from patients who had been hospitalized for 48 h or longer. The prevalence of extended-spectrum β-lactamase (ESBL)-producing pathogens was low. The decline in susceptibility rates with time was remarkable for ceftazidime (P = 0.036), ciprofloxacin (P = 0.029), and levofloxacin (P = 0.018). The most effective antibiotics, i.e., those that were active against more than 90% of Enterobacteriaceae, were amikacin, cefepime, imipenem, ertapenem, and piperacillin-tazobactam. Susceptibility of P. aeruginosa to anti-pseudomonal agents was greater than 80%. In this study, we found an overall increase in resistance to antimicrobial agents among Gram-negative bacilli isolated from patients with hepatobiliary tract infections in Taiwan. Surveillance of antimicrobial susceptibility and updates of treatment guidelines are recommended to help achieve optimal therapy for patients with hepatobiliary infections.

In vitro efficacy of fosfomycin-containing regimens against methicillin-resistant Staphylococcus aureus in biofilms

OBJECTIVES

To compare the in vitro antibacterial efficacy of antistaphylococcal antibiotics in combination with fosfomycin or rifampicin, using a biofilm model.

METHODS

The antibacterial activities of fusidic acid, linezolid, vancomycin, teicoplanin, rifampicin, minocycline, fosfomycin and tigecycline, individually and in fosfomycin or rifampicin combinations, were measured against planktonic or biofilm-embedded methicillin-resistant Staphylococcus aureus (MRSA) with susceptible and resistant breakpoint concentrations (SBCs and RBCs, respectively), using the MTT-staining method and by counting the number of cfu in the biofilms.

RESULTS

Linezolid alone at its SBC, and fosfomycin, linezolid, minocycline and tigecycline at their RBCs, exhibited killing effects on biofilm-embedded MRSA (P < 0.0001). Of the eight fosfomycin combinations studied, fosfomycin combined with linezolid, minocycline, vancomycin or teicoplanin at their respective SBCs, exhibited enhanced antibacterial activities (P < 0.0001) when compared with the control group, and outperformed rifampicin combinations (P < 0.01). The killing effects of fosfomycin combinations at their respective RBCs were better than those at their respective SBCs (P < 0.05). Significantly enhanced killing effects were observed with fosfomycin in combination with vancomycin or teicoplanin, compared with vancomycin or teicoplanin alone. For 10 randomly selected MRSA isolates, the results of colony counting in biofilms were comparable with those of the MTT-staining method.

CONCLUSIONS

Fosfomycin enhanced the activities of linezolid, minocycline, vancomycin and teicoplanin. These combinatorial treatments were even better than rifampicin combination regimens, and may provide therapeutic advantages in catheter-related or prosthetic joint infections.

Ibuprofen worsens Streptococcus pyogenes soft tissue infections in mice

BACKGROUND

Group A streptococcus (GAS) is a common cause of soft tissue infection. Nonsteroidal anti-inflammatory drugs have been reported to worsen GAS soft tissue infections.

METHODS

A mouse model of GAS soft tissue infection was developed. The extent of cutaneous lesions, tissue damage, release of inflammatory cytokines, and survival rates were compared between mice with and without ibuprofen administration after GAS soft tissue infection.

RESULTS

All twelve mice without ibuprofen administration survived for at least 10 days. In contrast, mortality rate of 14 mice with ibuprofen therapy was 72.5%. Ibuprofen-treated mice exhibited more evident macrophage infiltration and tissue damage in the GAS-infected soft tissues. In GAS-infected mice, tissue levels of interleukin 6 and tumor necrosis factor alpha were significantly higher in ibuprofen-treated mice than those in the control group.

CONCLUSIONS

The results supported the concept that ibuprofen use in GAS soft tissue infections might induce the development of severe necrotizing infections and increase mortality rate.

Risk factors associated with Sphingomonas paucimobilis infection

BACKGROUND

Sphingomonas paucimobilis is rarely isolated from clinical specimens and it is associated with a great variety of infections. The aim of this study is to investigate the microbiological and clinical features of S paucimobilis infection in southern Taiwan.

METHODS

S paucimobilis isolates from the microbiology laboratory of Chi-Mei Medical Center and their relevant clinical data from October 2005 to October 2009 were retrospectively reviewed.

RESULTS

A total of 55 patients with documented S paucimobilis infections were identified. Among them, 29 (52.7%) have community-acquired infections and 13 of them presented with primary bacteremia (44.8%). Multivariate logistic regression showed that community-acquired infection [adjusted odds ratio 13.473, 95% confidence interval (CI) 1.79-101.41, p = 0.01], diabetes mellitus (adjusted odds ratio 7.03, 95% CI 1.16-42.66, p = 0.03), and alcoholism (adjusted OR 10.87, 95% CI 1.00-117.69, p = 0.05) were significant risk factors for S paucimobilis primary bacteremia. Most of those who have health care-associated S paucimobilis infections presented with pneumonia (10 of 26, 38.5%) and only 7.7% presented with catheter-related infection. The overall mortality rate was 5.5%.

CONCLUSION

Community-acquired S paucimobilis infections were not uncommon, mainly presenting with primary bacteremia. Multivariate analysis showed that community-acquired infection, diabetes mellitus, and alcoholism were significant risk factors for primary bacteremia.

Retrospective evaluation of occurrence of skin injuries in interventional cardiac procedures

Interventional cardiology procedures can involve high doses to patients and, in particular, to patients' skin, the tissue at greatest risk of deterministic injuries. The evaluation of skin dose from interventional procedures is recommended, but difficult because of the amount of different X-ray fields and projections used in a procedure. For this reason, a retrospective follow-up study has been developed to identify skin injuries in patients submitted to one or more cardiac interventions in the Udine hospital between 1998 and 2002. Seventy-eight patients with a cumulative dose-area product >300 Gy cm2 were selected from 3332 patients, who underwent 5039 procedures. In this group the maximum skin dose was 6.7 Gy. The clinical follow-up, performed using the LENT-SOMA methodology, has not detected skin injuries and this result allows a frequency to be estimated for skin injuries in patients undergoing repeated cardiac procedures of <3 x 10(-4) in our centre.

A study to validate the method based on DIMOND quality criteria for cardiac angiographic images

A method based on image quality criteria (QC) for cine-angiography was developed to measure the quality of cine-angiograms (CA). A series of 30 CA for left ventriculography (LV) and left and right coronary angiography (LCA, RCA) have been scored and 172 readings were obtained. Standard deviation of quality scores indicated the reproducibility of the method. Each part of CA was examined separately, giving scores for LV, LCA and RCA and a total score (TS), with clinical (C) and technical (T) criteria defined and examined separately. In 83% of the studies TS was >0.8 and with standard deviation from 0.02 to 0.21. In general, LV had a lower score and greater disagreement compared with RCA and LCA. Disagreement was greater in T, compared with C. In conclusion, these results indicate that QC, translated into a scoring system, yields reproducible data on the quality of cardiac images.

Weight configurations of trained perceptrons

We strive to predict the function mapping and rules performed by a trained perceptron from studying the weights. We derive a few properties of the trained weights and show how the perceptron's representation of knowledge, rules and functions depend on these properties. Two types of perceptrons are studied--one case with continuous inputs and one hidden layer, the other a simple binary classifier with boolean inputs and no hidden units.