Antibiotic-resistant gram-negative bacterial infections in patients with cancer

Multidrug Resistant Enteric Bacteria from Cancer Patients Admitted in Douala Laquintinie Hospital, Littoral Region of Cameroon

Patients with cancer have weakened immune systems, making them more vulnerable to infections. This study was carried out to determine the bacterial origins of enteric disorders in cancer patients and noncancer patients at the Oncology Department of Laquintinie Hospital in Douala. A cross-sectional study was conducted from October 2021 to March 2023. Stool samples from 307 cancer patients with enteric disorders and 200 noncancer patients with enteric disorders were examined to diagnose the presence of bacteria using various techniques. Among all participants in this study, 62.13% were female and 37.87% were male. The average age of the participants was 46.38 ± 15.81 years, with a minimum age of 10 years and a maximum age of 84 years. The average age of participants was significantly higher (p < 0.000) in cancer patients (49.54 ± 14.65 years) compared to noncancer patients (41.53 ± 16.33 years). Proteus mirabilis, Proteus vulgaris, Salmonella typhi, Enterobacter cloacae, Klebsiella pneumoniae, Yersinia intemedia, and Klebsiella oxytoca were more frequently isolated in cancer patients than in noncancer patients, with the respective percentages of 56.25% versus 43.75%, 50.00% versus 50.00%, 61.66% versus 38.34%, 66.66% versus 33.34%, 72.22% versus 27.78%, 80.00 versus 20.00%, and 100% versus 0.00%. Most isolates were sensitive to imipenem (IMP), gentamicin (GEN), and amikacin (AMK). Proteus vulgaris, the most prevalent isolate, showed significantly high resistance (with p < 0.05) in cancer patients compared to noncancer patients at amoxicillin/clavuranic acid (AMC) (89.13% versus 41.30%), ceftriaxone (CTR) (63.04% versus 39.13%), ciprofloxacin (CIP) (65.22% versus 34.18%), and tetracycline (TET) (93.48% versus 63.04%). Multidrug resistance was observed in cancer patients compared to noncancer patients for Klebsiella pneumoniae (85.00% versus 60.00%), Salmonella typhi (84.62% versus 60.00%), and Klebsiella oxytoca (86.49% versus 43.48%). The increase in the number of Gram-negative infections among cancer patients, as shown in the present study, highlights the need for broad-spectrum therapy and effective planning of control programs to reduce bacterial diseases among cancer patients.

Seven-day antibiotic therapy for Enterobacterales bacteremia in high-risk neutropenic patients: toward a new paradigm

PURPOSE

Data on short courses of antibiotic therapy for Enterobacterales bacteremia in high-risk neutropenic patients are limited. The aim of the study was to describe and compare the frequency of bacteremia relapse, 30-day overall and infection-related mortality, Clostridiodes difficile infection and length of hospital stay since bacteremia among those who received antibiotic therapy for 7 or 14 days.

METHODS

This is a multicenter, prospective, observational cohort study in adult high-risk neutropenic patients with hematologic malignancies or hematopoietic stem cell transplant and monomicrobial Enterobacterales bacteremia. They received appropriate empirical antibiotic therapy, had a clinical response within 7 days, and infection source control. Clinical, epidemiological and outcomes variables were compared based on 7 or 14 days of AT.

RESULTS

Two hundred patients were included (100, 7-day antibiotic therapy; 100, 14-day antibiotic therapy). Escherichia coli was the pathogen most frequently isolated (47.5%), followed by Klebsiella sp. (40.5%). Among those patients that received 7-day vs. 14-day antibiotic course, a clinical source of bacteremia was found in 54% vs. 57% (p = 0.66), multidrug-resistant Enterobacterales isolates in 28% vs. 30% (p = 0.75), and 40% vs. 47% (p = 0.31) received combined empirical antibiotic therapy. Overall mortality was 3% vs. 1% (p = 0.62), in no case related to infection; bacteremia relapse was 7% vs. 2% (p = 0.17), and length of hospital stay since bacteremia had a median of 9 days (IQR: 7-15) vs. 14 days (IQR: 13-22) (p =  < 0.001).

CONCLUSIONS

These data suggest that seven-day antibiotic therapy might be adequate for patients with high-risk neutropenia and Enterobacterales bacteremia, who receive appropriate empirical therapy, with clinical response and infection source control.

In Vivo and in Vitro activity of colistin-conjugated bimetallic silver-copper oxide nanoparticles against Pandrug-resistant Pseudomonas aeruginosa

BACKGROUND

Addressing microbial resistance urgently calls for alternative treatment options. This study investigates the impact of a bimetallic formulation containing colistin, silver, and copper oxide on a pandrug-resistant, highly virulent Pseudomonas aeruginosa (P. aeruginosa) isolate from a cancer patient at the National Cancer Institute, Cairo University, Egypt.

METHODS

Silver nanoparticles (Ag NPs), copper oxide nanoparticles (CuO NPs), and bimetallic silver-copper oxide nanoparticles (Ag-CuO NPs) were synthesized using gamma rays, combined with colistin (Col), and characterized by various analytical methods. The antimicrobial activity of Col-Ag NPs, Col-CuO NPs, and bimetallic Col-Ag-CuO NPs against P. aeruginosa was evaluated using the agar well diffusion method, and their minimum inhibitory concentration (MIC) was determined using broth microdilution. Virulence factors such as pyocyanin production, swarming motility, and biofilm formation were assessed before and after treatment with bimetallic Col-Ag-CuO NPs. The in vivo efficacy was evaluated using the Galleria mellonella model, and antibacterial mechanism were examined through membrane leakage assay.

RESULTS

The optimal synthesis of Ag NPs occurred at a gamma ray dose of 15.0 kGy, with the highest optical density (OD) of 2.4 at 375 nm. Similarly, CuO NPs had an optimal dose of 15.0 kGy, with an OD of 1.5 at 330 nm. Bimetallic Ag-CuO NPs were most potent at 15.0 kGy, yielding an OD of 1.9 at 425 nm. The MIC of colistin was significantly reduced when combined with nanoparticles: 8 µg/mL for colistin alone, 0.046 µg/mL for Col-Ag NPs, and 0.0117 µg/mL for Col-Ag-CuO NPs. Bimetallic Col-Ag-CuO NPs reduced the MIC four-fold compared to Col-Ag NPs. Increasing the sub-inhibitory concentration of bimetallic nanoparticles from 0.29 × 10-2 to 0.58 × 10-2 µg/mL reduced P. aeruginosa swarming by 32-64% and twitching motility by 34-97%. At these concentrations, pyocyanin production decreased by 39-58%, and biofilm formation was inhibited by 33-48%. The nanoparticles were non-toxic to Galleria mellonella, showing 100% survival by day 3, similar to the saline-treated group.

CONCLUSIONS

The synthesis of bimetallic Ag-CuO NPs conjugated with colistin presents a promising alternative treatment for combating the challenging P. aeruginosa pathogen in hospital settings. Further research is needed to explore and elucidate the mechanisms underlying the inhibitory effects of colistin-bimetallic Ag-CuO NPs on microbial persistence and dissemination.

Frequency of Fecal Carriage of ESBL Resistance Genes in Multidrug-Resistant Pseudomonas aeruginosa Isolates from Cancer Patients at Laquintinie Hospital, Douala, Littoral Region, Cameroon

Background. Opportunistic infections are the second cause of death among cancer patients. This study aimed at determining the antimicrobial profile and the prevalence of extended-spectrum beta-lactamase (ESBL)-gene carriage of Pseudomonas aeruginosa isolates among cancer patients at the Douala Laquintinie Hospital, Littoral Region of Cameroon. Between October 2021 and March 2023, 507 study participants were recruited among whom 307 (60.55%) were cancer patients, compared to 200 (39.45%) noncancer patients. Fifty-eight P. aeruginosa isolates were isolated from fecal samples of forty-five cancer patients and thirteen noncancer patients using Cetrimide agar. The antimicrobial resistance profile of the isolates was determined using the Kirby-Bauer disk diffusion method. The polymerase chain reaction was used to detect the presence of extended-spectrum beta-lactamase genes among P. aeruginosa isolates. P. aeruginosa showed significant resistance rates in cancer patients compared to noncancer patients to imipenem, cefotaxime, and ceftazidime, piperacillin-tazobactam, ticarcillin-clavulanic acid, and ciprofloxacin. The multidrug resistance (MDR) rate was significantly (p < 0.05) higher in cancer patients than in noncancer patients. The frequency of beta-lactamase genes in the 58 ESBL-producing P. aeruginosa isolates was determined as 72.41% for bla TEM, 37.93% for bla OXA, 74.14% for blaCTX-M, and 44.83% for bla SHV genes. The study revealed an alarmingly high prevalence of fecal carriage of ESBL-producing P. aeruginosa with a high rate of MDR among cancer patients. It indicates that regular monitoring and surveillance of ESBL-producing P. aeruginosa among cancer patients are needed to improve the management of patients.

Antibiotic Resistance Profile of Staphylococcus aureus in Cancer Patients at Laquintinie Hospital in Douala, Littoral Region, Cameroon

Cancer and chemotherapy predispose the patients to various bacterial infections. This study is aimed at isolating and establishing the distribution of antibiotic-resistant Staphylococcus aureus from fecal samples in subjects with cancer admitted to the Oncology Department at Laquintinie Hospital in Douala, in the Littoral Region of Cameroon. A cross-sectional study was conducted from October 2021 to March 2023. Cancer and noncancer patients were suffering from Staphylococcus aureus infection. The isolation of Staphylococcus aureus was based on culture on the specific medium. The Kirby-Bauer disk diffusion method was used for drug susceptibility testing. Of the 507 patients studied, 307 (60.55%) were cancer patients, compared to 200 (39.45%) noncancer patients. S. aureus was isolated in 81 (15.97%) participants, among which 62 (76.55%) were cancer patients and 19 (23.45%) were noncancer patients. In the study population, 31.92% of participants had breast cancer, followed by cervical cancer (13.68%) and leukemia (7.17%). Staphylococcus aureus isolates showed high resistance rates in cancer patients compared to noncancer patients to amoxicillin-clavulanic acid (AMC, 77.42% versus 31.58%), cefoxitin (FOX, 80.65% versus 63.16%), ciprofloxacin (CIP, 75.81% versus 26.32%), ofloxacin (OFX, 69.35% versus 31.58%), fusidic acid (FUS, 70.97% versus 53.63%), and tetracycline (TET, 85.48% versus 78.95%). Staphylococcus aureus showed a significant increase in multidrug-resistant (MDR) and methicillin-resistant (MRSA) phenotypes in cancer patients compared to noncancer patients (p < 0.05). The prevalence of MRSA was 76.54%, higher than that of methicillin-sensitive Staphylococcus aureus (MSSA) (23.46%). The frequency of MRSA was significantly higher (p < 0.001) in cancer patients (80.65%) than in noncancer patients (19.35%). This study showed that there is an association between antibiotic resistance and cancer status. Research and interventions must be focused on the cancer population to combat the appearance of MDR bacteria due to the loss of effectiveness of antibiotics.

Deciphering the Coevolutionary Dynamics of L2 β-Lactamases via Deep Learning

L2 β-lactamases, serine-based class A β-lactamases expressed by Stenotrophomonas maltophilia, play a pivotal role in antimicrobial resistance (AMR). However, limited studies have been conducted on these important enzymes. To understand the coevolutionary dynamics of L2 β-lactamase, innovative computational methodologies, including adaptive sampling molecular dynamics simulations, and deep learning methods (convolutional variational autoencoders and BindSiteS-CNN) explored conformational changes and correlations within the L2 β-lactamase family together with other representative class A enzymes including SME-1 and KPC-2. This work also investigated the potential role of hydrophobic nodes and binding site residues in facilitating the functional mechanisms. The convergence of analytical approaches utilized in this effort yielded comprehensive insights into the dynamic behavior of the β-lactamases, specifically from an evolutionary standpoint. In addition, this analysis presents a promising approach for understanding how the class A β-lactamases evolve in response to environmental pressure and establishes a theoretical foundation for forthcoming endeavors in drug development aimed at combating AMR.

Development of rabbit models of ventilator-associated bacterial pneumonia produced by carbapenem-resistant Pseudomonas aeruginosa

Ventilator-associated bacterial pneumonia (VABP) is among the most intractable of carbapenem-resistant Gram-negative bacterial infections. New antimicrobial agents are critically needed for the treatment of VABP. However, current conventionally used animal model systems are inadequate to meet this challenge. We, therefore, developed rabbit models of VABP caused by carbapenem-resistant Pseudomonas aeruginosa. Persistently neutropenic New Zealand White rabbits were used throughout the study. The early-phase intubated model (0-24 h) received mechanical ventilation, while the late-phase intubated model (72-96 h) was ambulatory. The following outcome parameters were studied: survival, residual tissue bacterial burden (CFU/g), residual BAL bacterial burden (CFU/mL), lung weights, pulmonary lesion score, histology, O2 saturation, radiographic imaging, and histology. Each anesthetized rabbit received a predetermined endotracheal bacterial inoculum, and ventilators were set to FiO2 = 40% and PEEP = 8 mmHg. Within the first 12 h post-inoculation, mean bacterial burdens in lung tissue and BAL fluid, respectively, were established at approximately 107 CFU/g and 106 CFU/mL, persisted through 24 h in the early-phase model and increased in the late-phase model to approximately 108 CFU/g and 107 CFU/mL. Mean max SpO2 was ≥98 mmHg, and mean nadir SpO2 was ≥68 mmHg. Serial thoracic radiographs demonstrated progressive multilobar pneumonic infiltrates. Lung histology revealed progressive focal bronchopneumonia, coagulative necrosis, intra-alveolar hemorrhage, alveolar epithelial cell necrosis, and bacterial microcolonies. The new rabbit model of VABP produced by carbapenem-resistant Pseudomonas aeruginosa recapitulates the pathophysiological, microbiological, diagnostic imaging, and histological patterns of human disease by which to assess critically needed new antimicrobial agents against this lethal infection.

Ceftazidime-Avibactam Improves Outcomes in High-Risk Neutropenic Patients with Klebsiella pneumoniae Carbapenemase-Producing Enterobacterales Bacteremia

Few studies have evaluated the efficacy of ceftazidime-avibactam (CA) for Klebsiella pneumoniae carbapenemase-producing Enterobacterales bacteremia (KPC-PEB) in high-risk neutropenic patients. This is a prospective multicenter observational study in high-risk neutropenic patients with multi-drug resistant Enterobacterales bacteremia. They were compared according to the resistance mechanism and definitive treatment provided: KPC-CPE treated with CA (G1), KPC-CPE treated with other antibiotics (G2), and patients with ESBL-producing Enterobacterales bacteremia who received appropriate definitive therapy (G3). Thirty-day mortality was evaluated using a logistic regression model, and survival was analyzed with Kaplan-Meier curves. A total of 238 patients were included: 18 (G1), 52 (G2), and 168 (G3). Klebsiella spp. (60.9%) and Escherichia coli (26.4%) were the Enterobacterales most frequently isolated, and 71% of the bacteremias had a clinical source. The resistance profile between G1 and G2 was colistin 35.3% vs. 36.5%, amikacin 16.7% vs. 40.4%, and tigeclycline 11.1% vs. 19.2%. The antibiotics prescribed in combination with G2 were carbapenems, colistin, amikacin, fosfomycin, tigecycline, and fluoroquinolones. Seven-day clinical response in G1 vs. G2 vs. G3 was 94.4% vs. 42.3% vs. 82.7%, respectively (p < 0.001). Thirty-day overall mortality in G1 vs. G2 vs. G3 was 22.2% vs. 53.8% vs. 11.9%, respectively (p < 0.001), and infection-related mortality was 5.5% vs. 51.9% vs. 7.7% (p < 0.001). The independent risk factors for mortality were Pitt score > 4: OR 3.63, 95% CI, 1.18-11.14 (p = 0.025) and KPC-PEB treated with other antibiotics: OR 8.85, 95% CI, 2.58-30.33 (p = 0.001), while 7-day clinical response was a protective factor for survival: OR 0.02, 95% CI, 0.01-0.08 (p < 0.001). High-risk neutropenic patients with KPC-CPE treated with CA had an outcome similar to those treated for ESBL-producing Enterobacterales, with higher 7-day clinical response and lower overall and infection-related mortality than those treated with other antibiotics. In view of these data, CA may be considered the preferred therapeutic option for KPC-PEB in high-risk neutropenic patients.

Evaluating antimicrobial duration for Gram-negative bacteremia in patients with neutropenia due to hematologic malignancy or hematopoietic stem cell transplantation

BACKGROUND

In the management of Gram-negative bloodstream infection (GN-BSI), short antimicrobial courses have been increasingly demonstrated to be non-inferior to prolonged therapy, with lower risk of Clostridioides difficile infection (CDI) and emergence of multi-drug resistant (MDR) organisms. However, immunocompromised hosts were excluded from these studies. We investigated outcomes of short (≤10 days), intermediate (11-14 days), and prolonged (≥15 days) antimicrobial durations for GN-BSI in neutropenic patients.

METHODS

A retrospective cohort study was conducted on neutropenic patients with monomicrobial GN-BSI between 2018 and 2022. The primary outcome was a composite of all-cause mortality and microbiologic relapse within 90 days after therapy completion. The secondary outcome was a composite of 90-day CDI and development of MDR-GN bacteria. Cox regression analysis with propensity score (PS) adjustment was used to compare outcomes between the three groups.

RESULTS

A total of 206 patients were classified into short (n = 67), intermediate (n = 81), or prolonged (n = 58) duration. Neutropenia was predominantly secondary to hematopoietic stem cell transplantation (48%) or hematologic malignancy (35%). The primary sources of infection included intra-abdominal (51%), vascular catheter (27%), and urinary (8%). Most patients received definitive therapy with cefepime or carbapenem. No significant difference in the primary composite endpoint was observed for intermediate versus short (PS-adjusted hazard ratio [aHR] 0.89; 95% confidence interval [95% CI] 0.39-2.03) or prolonged versus short therapy (PS-aHR 1.20; 95% CI 0.52-2.74). There was no significant difference in the secondary composite endpoint of CDI or MDR-GN emergence.

CONCLUSION

Our data suggest that short antimicrobial courses had comparable 90-day outcomes as intermediate and prolonged regimens for GN-BSI among immunocompromised patients with neutropenia.

In vitro Antimicrobial Activity and Dose Optimization of Eravacycline and Other Tetracycline Derivatives Against Levofloxacin-Non-Susceptible and/or Trimethoprim-Sulfamethoxazole-Resistant Stenotrophomonas maltophilia

Purpose

To better guide clinical use, we determined the in vitro antimicrobial activity of the new drug eravacycline and other tetracycline derivatives against levofloxacin (LVFX)-non-susceptible and/or trimethoprim-sulfamethoxazole (TMP-SMZ)-resistant Stenotrophomonas maltophilia and evaluated their dosing regimens.

Methods

Seventy-seven unique strains of S. maltophilia were isolated from sputa samples and airway aspirate samples that were either LVFX-non-susceptible and/or TMP-SMZ-resistant. Monte Carlo simulations were performed for different dosing regimens according to the population pharmacokinetic parameters of antibiotics in patients with respiratory tract infections at the minimum inhibitory concentration (MIC).

Results

Eravacycline had excellent in vitro antibacterial activity against LVFX-non-susceptible and/or TMP-SMZ-resistant S. maltophilia. Monte Carlo simulations showed that for LVFX-non-susceptible strains, the cumulative fraction of response (CFR) of minocycline at the conventional recommended dose of 100 mg q12 h was 90.90%; for TMP-SMZ-resistant strains, the CFR of minocycline at a high dose of 200 mg q12 h was only 91.64%. For strains resistant to both LVFX and TMP-SMZ, the CFR of minocycline at a high dose of 200 mg q12 h was 89.81%. In contrast, the CFR of tigecycline was less than 40%, even at a dose of 100 mg q12 h.

Conclusion

For pneumonia, minocycline is better for S. maltophilia that is non-susceptible to LVFX; for TMP-SMZ-resistant strains and strains that are not susceptible to either LVFX or TMP-SMZ, the efficiency of eravacycline requires further evaluation. Eravacycline may be a better choice for extremely resistant S. maltophilia strains that are non-susceptible to LVFX, TMP-SMZ, and minocycline.

The Triple Crown: NO, CO, and H2S in cancer cell biology

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are three endogenously produced gases with important functions in the vasculature, immune defense, and inflammation. It is increasingly apparent that, far from working in isolation, these three exert many effects by modulating each other's activity. Each gas is produced by three enzymes, which have some tissue specificities and can also be non-enzymatically produced by redox reactions of various substrates. Both NO and CO share similar properties, such as activating soluble guanylate cyclase (sGC) to increase cyclic guanosine monophosphate (cGMP) levels. At the same time, H2S both inhibits phosphodiesterase 5A (PDE5A), an enzyme that metabolizes sGC and exerts redox regulation on sGC. The role of NO, CO, and H2S in the setting of cancer has been quite perplexing, as there is evidence for both tumor-promoting and pro-inflammatory effects and anti-tumor and anti-inflammatory activities. Each gasotransmitter has been found to have dual effects on different aspects of cancer biology, including cancer cell proliferation and apoptosis, invasion and metastasis, angiogenesis, and immunomodulation. These seemingly contradictory actions may relate to each gas having a dual effect dependent on its local flux. In this review, we discuss the major roles of NO, CO, and H2S in the context of cancer, with an effort to highlight the dual nature of each gas in different events occurring during cancer progression.

Infections in Children with Cancer Admitted in an Oncology Reference Hospital: A Cross-sectional Study

Pediatric oncology patients are usually immunosuppressed due to factors such as the neoplasm and its treatment, making them more susceptible to infections. This article aims to determine the infection profile of pediatric oncology patients admitted to an oncology reference hospital in Natal, Rio Grande do Norte, Brazil. A retrospective and cross-sectional study was conducted, collecting data from patients hospitalized due to infection in a pediatric oncology unit exclusively for the Brazilian public health system, spanning from 2018 to 2021. A total of 168 episodes of infections were identified in 96 patients, resulting in 157 hospitalizations. Among the patients with infections, 62.4% had hematological malignancies, and out of these cases, 74.6% specifically had Acute Lymphoid Leukemia. The Escherichia coli (31.9%) was the most prevalent microorganism isolated from the samples. Multidrug-resistant microorganisms accounted for 52% of all identified microorganisms. Fluoroquinolones and beta-lactam were the most prevalent antibiotic classes in the analyzed antibiograms. Factors such as Sex, type of cancer, chemotherapy in the last 30 days, were found to be associated with the occurrence of infection (p < 0.05). Conducting epidemiological studies regarding infections in pediatric oncology is crucial to development of empirical protocols, and the implementation of strategies to better control future infections.

Characteristics, Outcomes, and Clinical Indicators of Bloodstream Infections in Neutropenic Patients with Hematological Malignancies: A 7-Year Retrospective Study

Purpose

The aim of this study was to investigate the current epidemiology, its changes during the study years, and inflammatory biomarkers of bacterial bloodstream infections (BSIs) in neutropenic patients with hematological malignancies. We assessed mortality risk factors and multidrug-resistant (MDR) gram-negative BSI predictors.

Patients and Methods

We conducted a retrospective study from January 2015 to December 2021, which included adult neutropenic oncohematological patients with confirmed BSIs. We used univariable and multivariable analyses to analyze the risk factors. Each index's reliability for bacterial BSI diagnosis was assessed using the receiver-operating characteristic curve and area under the curve.

Results

A total of 514 isolates were obtained from the 452 patients. The average mortality was 17.71%. Gram-negative organisms were the predominant causes of BSI. Escherichia coli was the most common microorganism (49.90%). The overall variation trend of the isolation rate of MDR and carbapenem-resistant gram-negative bacteria increased. Multivariate analysis indicated that: 1) neutropenia that lasted for more than 7 days, patients ≥ 60 years of age, septic shock, hospitalization for >20 days, BSI with a carbapenem-resistant strain, and treatment with linezolid or vancomycin in infections lasting less than 30 days were independent mortality risk factors; 2) severe neutropenia exceeding 7 days, unreasonable empirical therapy, and receipt of aminoglycosides or 3rd or 4th generation cephalosporins in infections lasting less than 30 days were independent risk factors of MDR gram-negative bacteria. Procalcitonin, absolute neutrophil count, and white blood cell indicate higher diagnostic accuracy for BSIs. Moreover, bacteria time to detection was better at differentiating Gram-negative and Gram-positive bacterial infections.

Conclusion

We analyzed the risk factors for BSI neutropenic patients with hematological malignancies, the distribution of bacteria, antibiotic resistance, and the changes in clinical parameters. This single-center retrospective study may provide clinicians with novel insights into the diagnosis and treatment of BSI to improve future clinical outcomes.

An Overview of Selected Bacterial Infections in Cancer, Their Virulence Factors, and Some Aspects of Infection Management

In cancer development and its clinical course, bacteria can be involved in etiology and secondary infection. Regarding etiology, various epidemiological studies have revealed that Helicobacter pylori can directly impact gastric carcinogenesis. The Helicobacter pylori-associated virulence factor cytotoxin-associated gene A perhaps plays an important role through different mechanisms such as aberrant DNA methylation, activation of nuclear factor kappa B, and modulation of the Wnt/β-catenin signaling pathway. Many other bacteria, including Salmonella and Pseudomonas, can also affect Wnt/β-catenin signaling. Although Helicobacter pylori is involved in both gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma, its role in the latter disease is more complicated. Among other bacterial species, Chlamydia is linked with a diverse range of diseases including cancers of different sites. The cellular organizations of Chlamydia are highly complex. Interestingly, Escherichia coli is believed to be associated with colon cancer development. Microorganisms such as Escherichia coli and Pseudomonas aeruginosa are frequently isolated from secondary infections in cancer patients. In these patients, the common sites of infection are the respiratory, gastrointestinal, and urinary tracts. There is an alarming rise in infections with multidrug-resistant bacteria and the scarcity of suitable antimicrobial agents adversely influences prognosis. Therefore, effective implementation of antimicrobial stewardship strategies is important in cancer patients.

Mutation-based fluoroquinolone resistance in carbapenem-resistant Acinetobacter baumannii and Escherichia coli isolates causing catheter-related bloodstream infections

Objective

We studied the presence of mutations in the chromosomal quinolone resistance-determining regions (QRDRs) of the fluoroquinolone targets gyrA and parC genes and detected the carbapenem resistance (CR) encoding genes among Acinetobacter baumannii and Escherichia coli isolates from catheter-related bloodstream infections (CRBSIs).

Methods

The study included 39 non-duplicate isolates of A. baumannii (14/39, 35.9%) and E. coli (25/39, 64.1%) isolated from 128 confirmed CRBSIs cases. Antimicrobial susceptibility testing was performed, followed by an evaluation of biofilm formation using the tissue culture plate method. The carbapenemase encoding genes were detected by multiplex polymerase chain reaction (PCR). The mutations in QRDRs of gyrA and parC genes were determined by singleplex PCR amplification followed by DNA sequencing and BlastN analysis in the GenBank database. DNA and the translated amino acid sequences were analyzed using the Mega7 bioinformatics tool.

Results

Multidrug-resistant (MDR) E. coli and A. baumannii isolates harbored CR encoding genes and combined gyrA and parC genes mutation. The specific substitutions observed in GyrA were Cys173Arg, Cys174Gly, Asp80Val, Tyr178ASP, Tyr84Gly, Glu85Lys, Ser172Leu, and Asp176Asn, while the specific substitutions observed in the ParC amino acid sequence were point mutation 62 Arg, Phe60Leu, Ils66Val, and Gln76Lys. Point mutation 62Arg was detected in two A. baumannii isolates, whereas Ser172Leu mutation was observed in two E. coli isolates.

Conclusion

The presence of new single and multiple mutations in QRDR causes the emergence of MDR E. coli and A. baumannii infections in carbapenem-resistant Enterobacteriaceae in Egypt, requiring further investigation in Gram-negative bacteria.

Extended-spectrum beta-lactamase-producing Enterobacteriaceae related urinary tract infection in adult cancer patients: a multicenter retrospective study, 2015-2019

BACKGROUND

The aim of this study was to investigate the prevalence and risk factors of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae related urinary tract infections (UTI) in adult cancer patients.

METHODS

We conducted a retrospective study of three cancer hospitals centered on Cancer Hospital of Chinese Academy of Medical Sciences from 2015 to 2019. The clinical characters, risk factors and antimicrobial susceptibility of ESBL-producing Enterobacteriaceae UTI in adult cancer patients were described and analyzed.

RESULTS

A total of 4967 specimens of UTI were evaluated, of which 909 were positive. After excluding multiple infection bacteria, non-conforming strains, inconsistent pathological information, no drug sensitivity test or medical records, 358 episodes remained. Among them, 160 episodes belonged to ESBL-producing Enterobacteriaceae, while 198 were classified into non-ESBL group. The prevalence of ESBL UTI circled around 39.73 to 53.03% for 5 years. Subgroup analysis by tumor type revealed that 62.5% of isolates from patients with urological tumors were ESBL positive. Multivariate analysis showed that tumor metastasis (OR 3.41, 95%CI 1.84-6.30), urological cancer (OR 2.96, 95%CI 1.34-6.53), indwelling catheter (OR 2.08, 95%CI 1.22-3.55) and surgery or invasive manipulation (OR 1.98, 95%CI 1.13-3.50) were the independent risk factors. According to antimicrobial sensitivity, meropenem, imipenem and piperacillin/tazobactam were the most commonly used antibiotics for ESBL-producing Enterobacteriaceae UTI.

CONCLUSIONS

In view of the high prevalence, clinicians should be alert to the occurrence of ESBL UTI, especially for patients with urological cancer or metastatic tumors. Regular replacement of urinary catheters, reduction of unnecessary invasive operations and selection of appropriate antibiotics are the necessary conditions to deal with the occurrence of ESBL UTI in adult cancer patients.

Short Course of Antibiotic Therapy for Gram-Negative Bacilli Bacteremia in Patients with Cancer and Hematopoietic Stem Cell Transplantation: Less Is Possible

Data about short courses of antibiotic therapy for Gram-negative bacilli (GNB) bacteremia in immunosuppressed patients are limited. This is a prospective observational study performed on adult patients with cancer and hematopoietic stem cell transplant (HSCT) who developed GNB bacteremia and received appropriate empirical antibiotic therapy (EAT), had a clinical response within 7 days and survived 48 h after the end of therapy. They received antibiotic therapy in the range of 7-15 days and were divided into short course, with a median of 7 days (SC), or long course, with a median of 14 days (LC). Seventy-four patients were included (SC: 36 and LC: 38). No differences were observed in baseline characteristics or in the presence of neutropenia: 58.3% vs. 60.5% (p = 0.84). Clinical presentation and microbiological characteristics were similar in SC and LC, respectively: clinical source of bacteremia 72.2% vs. 76.3% (p = 0.68); shock 2.8% vs. 10.5% (p = 0.35) and multidrug-resistant GNB 27.8% vs. 21.1% (p = 0.50). Overall, mortality was 2.8% vs. 7.9% (p = 0.61), and bacteremia relapse was 2.8% vs. 0 (p = 0.30). The length of hospitalization since bacteremia was 7 days (interquartile range (IQR), 6-15) for SC and 12 days (IQR, 7-19) (p = 0.021) for LC. In the case of patients with cancer or HSCT and GNB bacteremia who receive appropriate EAT with clinical response, 7 days of antibiotic therapy might be adequate.

Carbapenem-Resistant Enterobacteriaceae (CRE) among Children with Cancer: Predictors of Mortality and Treatment Outcome

Carbapenem-resistant Enterobacteriaceae (CRE) is an important emerging threat among pediatric cancer patients, with a high mortality rate. This retrospective study included all pediatric cancer patients with (CRE) bloodstream infections (BSIs) at a children's cancer hospital in Egypt (2013-2017). Two hundred and fifty-four pediatric cancer patients with CRE BSI were identified; 74% had hematological malignancies, and 26% had solid tumors. Acute myeloid leukemia was the most common hematological malignancy (50%). The main clinical features for acquiring CRE-BSI were previous antibiotics exposure (90%), profound neutropenia (84%), prolonged steroid use (45%), previous colonization with a resistant pathogen (35%), ICU admission within 90 days (28%), and central venous catheter use (24%). E. coli was the most common isolated pathogen (56%), followed by Klebsiella pneumoniae (37%). All isolates were resistant to carbapenem with an MIC < 4-8 μg/mL in 100 (45%) and >8 μg/mL in 153 (55%). The overall mortality rate was 57%, and 30 day mortality was reported in 30%. Upon multivariate analysis, for the patients with Klebsiella pneumoniae BSI, carbapenem resistance with an MIC > 8 μg/mL and associated typhlitis or pneumonia were predictors of poor outcome. In conclusion, CRE-BSI is a major threat among pediatric cancer patients in limited resource countries with limited options for treatment. Antimicrobial stewardship for early detection through routine screening, adequate empirical treatment, and timely adequate therapy may impact the outcome for such high-risk patient groups.

Development of a Clinical Score to Stratify the Risk for Carbapenem-Resistant Enterobacterales Bacteremia in Patients with Cancer and Hematopoietic Stem Cell Transplantation

Identifying the risk factors for carbapenem-resistant Enterobacterales (CRE) bacteremia in cancer and hematopoietic stem cell transplantation (HSCT) patients would allow earlier initiation of an appropriate empirical antibiotic treatment. This is a prospective multicenter observational study in patients from 12 centers in Argentina, who presented with cancer or hematopoietic stem-cell transplant and developed Enterobacterales bacteremia. A multiple logistic regression model identified risk factors for CRE bacteremia, and a score was developed according to the regression coefficient. This was validated by the bootstrap resampling technique. Four hundred and forty-three patients with Enterobacterales bacteremia were included: 59 with CRE and 384 with carbapenem-susceptible Enterobacterales (CSE). The risk factors that were identified and the points assigned to each of them were: ≥10 days of hospitalization until bacteremia: OR 4.03, 95% CI 1.88-8.66 (2 points); previous antibiotics > 7 days: OR 4.65, 95% CI 2.29-9.46 (2 points); current colonization with KPC-carbapenemase-producing Enterobacterales: 33.08, 95% CI 11.74-93.25 (5 points). With a cut-off of 7 points, a sensitivity of 35.59%, specificity of 98.43%, PPV of 77.7%, and NPV of 90.9% were obtained. The overall performance of the score was satisfactory (AUROC of 0.85, 95% CI 0.80-0.91). Finally, the post-test probability of CRE occurrence in patients with none of the risk factors was 1.9%, which would virtually rule out the presence of CRE bacteremia.

Zn (II)-porphyrin-based photochemically green synthesis of novel ZnTPP/Cu nanocomposites with antibacterial activities and cytotoxic features against breast cancer cells

This study focuses on synthesizing novel nanocomposites, zinc(II)tetrakis(4-phenyl)porphyrin/Cu nanoparticles (ZnTPP/Cu-NPs),with antibacterial activity, fabricated through a single-step green procedure. In this regard, the self-assembly of ZnTPP was carried out through an acid-base neutralization method to prepare ZnTPP nanoparticles. Then, the copper nanoparticles (Cu-NPs) were grown on ZnTPP nanoparticles through a visible-light irradiated photochemical procedure in the absence and presence of polyacrylic acid (PAA) as a modulator. The effect of PAA on the morphological properties of the prepared nanocomposites was evaluated. Eventually, the antibacterial activity of nanocomposites with different morphologies was investigated. In this way, the average zone of inhibition growth of diameter, minimum inhibitory concentration, and minimum bactericidal concentration values was determined. Besides, the cytotoxicity of the nanocomposites was evaluated by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay MCF-7and (HEK-293) cell lines. The specific features of the synthesized nanocomposites identified them as antibacterial compounds which have therapeutic effects on breast cancer.

Efficacy of Cefiderocol in Experimental Stenotrophomonas maltophilia Pneumonia in Persistently Neutropenic Rabbits

Stenotrophomonas maltophilia is an important cause of pneumonia in immunocompromised patients. Cefiderocol is a parenteral siderophore cephalosporin with potent in vitro activity against S. maltophilia. We evaluated the efficacy of cefiderocol in a neutropenic rabbit model of S. maltophilia pneumonia in comparison to trimethoprim-sulfamethoxazole (TMP-SMX). The cefiderocol area under the plasma drug concentration-time curve extrapolated to 8 h (AUC_0–8) was lower (423.0 ± 40.9 μg·h/mL versus 713.6 ± 40.1 μg·h/mL) and clearance higher (252.77 ± 38.9 mL/h/kg versus 142.6 ± 32.9 mL/h/kg) in infected versus noninfected rabbits. We studied a clinical bloodstream S. maltophilia isolate with an MIC of 0.03 μg/mL of cefiderocol. Time spent above the MIC of cefiderocol for the majority of S. maltophilia isolates in rabbits recapitulated the plasma concentration-time profile observed in adult humans at the licensed dose of 2 g given intravenously (i.v.). Experimental groups consisted of 120 mg/kg cefiderocol i.v. every 8 hours (q8h); TMP-SMX, 5 mg/kg i.v. Q12h, and untreated controls (UCs). Treatment was administered for 10 days. Survival in cefiderocol-treated rabbits (87%) was greater than that in TMP-SMX-treated (25%; P < 0.05) and UC (0%; P < 0.05) groups. There was no residual bacterial burden in lung tissue or bronchoalveolar lavage (BAL) fluid in the cefiderocol group. Residual bacterial burden was present in lung tissue and BAL fluid in the TMP-SMX group but was decreased in comparison to UCs (P < 0.001). Lung weights (markers of pulmonary injury) were decreased in cefiderocol-treated versus TMP-SMX (P < 0.001) and UC (P < 0.001) groups. Cefiderocol is highly active in treatment of experimental S. maltophilia pneumonia, laying the foundation for future clinical investigations against this lethal infection in immunocompromised patients.

Increased Innate Immune Susceptibility in Hyperpigmented Bacteriophage-Resistant Mutants of Pseudomonas aeruginosa

Bacteriophage (phage) therapy is an alternative to traditional antibiotic treatments that is particularly important for multidrug-resistant pathogens, such as Pseudomonas aeruginosa. Unfortunately, phage resistance commonly arises during treatment as bacteria evolve to survive phage predation. During in vitro phage treatment of a P. aeruginosa-type strain, we observed the emergence of phage-resistant mutants with brown pigmentation that was indicative of pyomelanin. As increased pyomelanin (due to hmgA gene mutation) was recently associated with enhanced resistance to hydrogen peroxide and persistence in experimental lung infection, we questioned if therapeutic phage applications could inadvertently select for hypervirulent populations. Pyomelanogenic phage-resistant mutants of P. aeruginosa PAO1 were selected for upon treatment with three distinct phages. Phage-resistant pyomelanogenic mutants did not possess increased survival of pyomelanogenic ΔhmgA in hydrogen peroxide. At the genomic level, large (~300 kb) deletions in the phage-resistant mutants resulted in the loss of ≥227 genes, many of which had roles in survival, virulence, and antibiotic resistance. Phage-resistant pyomelanogenic mutants were hypersusceptible to cationic peptides LL-37 and colistin and were more easily cleared in human whole blood, serum, and a murine infection model. Our findings suggest that hyperpigmented phage-resistant mutants that may arise during phage therapy are markedly less virulent than their predecessors due to large genomic deletions. Thus, their existence does not present a contraindication to using anti-pseudomonal phage therapy, especially considering that these mutants develop drug susceptibility to the familiar FDA-approved antibiotic, colistin.

Pseudomonas aeruginosa Infections in Cancer Patients

Pseudomonas aeruginosa (P. aeruginosa) is one of the most frequent opportunistic microorganisms causing infections in oncological patients, especially those with neutropenia. Through its ability to adapt to difficult environmental conditions and high intrinsic resistance to antibiotics, it successfully adapts and survives in the hospital environment, causing sporadic infections and outbreaks. It produces a variety of virulence factors that damage host cells, evade host immune responses, and permit colonization and infections of hospitalized patients, who usually develop blood stream, respiratory, urinary tract and skin infections. The wide intrinsic and the increasing acquired resistance of P. aeruginosa to antibiotics make the treatment of infections caused by this microorganism a growing challenge. Although novel antibiotics expand the arsenal of antipseudomonal drugs, they do not show activity against all strains, e.g., MBL (metalo-β-lactamase) producers. Moreover, resistance to novel antibiotics has already emerged. Consequently, preventive methods such as limiting the transmission of resistant strains, active surveillance screening for MDR (multidrug-resistant) strains colonization, microbiological diagnostics, antimicrobial stewardship and antibiotic prophylaxis are of particular importance in cancer patients. Unfortunately, surveillance screening in the case of P. aeruginosa is not highly effective, and a fluoroquinolone prophylaxis in the era of increasing resistance to antibiotics is controversial.

Clinical challenges treating Stenotrophomonas maltophilia infections: an update

Stenotrophomonas maltophilia is a non-fermenting, Gram-negative bacillus that has emerged as an opportunistic nosocomial pathogen. Its intrinsic multidrug resistance makes treating infections caused by S. maltophilia a great clinical challenge. Clinical management is further complicated by its molecular heterogeneity that is reflected in the uneven distribution of antibiotic resistance and virulence determinants among different strains, the shortcomings of available antimicrobial susceptibility tests and the lack of standardized breakpoints for the handful of antibiotics with in vitro activity against this microorganism. Herein, we provide an update on the most recent literature concerning these issues, emphasizing the impact they have on clinical management of S. maltophilia infections.

The interplay between anticancer challenges and the microbial communities from the gut

Cancer being an increasing burden on human health, the use of anticancer drugs has risen over the last decades. The physiological effects of these drugs are not only perceived by the host's cells but also by the microbial cells it harbors as commensals, notably the gut microbiota. Since the early '50 s, the cytotoxicity of anticancer chemotherapy was evaluated on bacteria revealing some antimicrobial activities that result in an established perturbation of the gut microbiota. This perturbation can affect the host's health through dysbiosis, which can lead to multiple complications, but has also been shown to have a direct effect on the treatment efficiency.We, therefore, conducted a review of literature focusing on this triangular relationship involving the microbial communities from the gut, the host's disease, and the anticancer treatment. We focused specifically on the antimicrobial effects of anticancer chemotherapy, their impact on mutagenesis in bacteria, and the perspectives of using bacteria-based tools to help in the diagnostic and treatment of cancer.

Infection prevention requirements for the medical care of immunosuppressed patients: recommendations of the Commission for Hospital Hygiene and Infection Prevention (KRINKO) at the Robert Koch Institute

In Germany, guidelines for hygiene in hospitals are given in form of recommendations by the Commission for Hospital Hygiene and Infection Prevention (Kommission für Krankenhaushygiene und Infektionsprävention, "KRINKO"). The KRINKO and its voluntary work are legitimized by the mandate according to § 23 of the Infection Protection Act (Infektionsschutzgesetz, "IfSG"). The original German version of this document was published in February 2021 and has now been made available to the international professional public in English. The guideline provides recommendations on infection prevention and control for immunocompromised individuals in health care facilities. This recommendation addresses not only measures related to direct medical care of immunocompromised patients, but also management aspects such as surveillance, screening, antibiotic stewardship, and technical/structural aspects such as patient rooms, air quality, and special measures during renovations.

Antibiotic Management of Patients with Hematologic Malignancies: From Prophylaxis to Unusual Infections

Purpose of Review

Patients with hematological malignancies are recognized for their high susceptibility and increased risk of developing infections associated with immunosuppression that can be caused by the infection itself or by the treatments that condition a decrease in the humoral and T lymphocyte response, so this review attempts to gather the main bacterial, viral, parasitic, and fungal agents that affect them and give recommendations for their approach and diagnosis.

Recent Findings

In recent years, with the discovery and use of new therapies including immunological and targeted treatments, it has been possible to improve the survival and response of patients with hematological malignancies; however, antimicrobial resistance has also increased; we have faced new and unknown microorganisms, such as the SARS-CoV-2 that caused the COVID-19 pandemic in the past year, and therefore, new risks and more severe infections are presented.

Summary

We present a review of the different circumstances where hematological malignancies increased the risk of infections and which microorganisms affect these patients, their characteristics, and the suggested prophylaxis.

Frequency of microbial isolates and pattern of antimicrobial resistance in patients with hematological malignancies: a cross-sectional study from Palestine

BACKGROUND

Infections are the main cause of death in patients with hematologic malignancies. This study aims to determine the microbial profile of infections in patients with hematologic malignancies and to determine the antimicrobial resistance patterns for these pathogens.

METHODS

A retrospective descriptive cross-sectional study was conducted from January 2018 to December 2019 at a large hematological center in Palestine. The medical data of hematologic malignancy patients with positive cultures were collected from the hematology/oncology department using the hospital information system, and data regarding the microbial isolates and their antimicrobial resistance were collected from the microbiology laboratory.

RESULTS

A total of 144 isolates were identified from different types of specimens, mostly blood samples. Of all isolates, 66 (45.8%) were gram-negative bacteria (GNB), 57 (39.6%) were gram-positive bacteria (GPB), and 21 (14.6%) were fungal isolates. The GNB that were most frequently isolated were Pseudomonas aeruginosa (27, 40.9%), followed by Escherichia coli (E. coli) (20, 30.3%). Fourteen isolates (24.6%) of GPB were Staphylococcus epidermidis followed by Enterococcus faecium (10, 17.5%) and Staphylococcus hemolyticus (10, 17.5%). The most frequent fungal pathogens were Candida species (20, 95.2%). GNB were found to be resistant to most antibiotics, mainly ampicillin (79.3%). Pseudomonas aeruginosa exhibited high resistance to ciprofloxacin (60%) and imipenem (59.3%). Among GPB, high resistance rates to oxacillin (91.1%) and amikacin (88.8%) were found. All isolated strains of Staphylococcus epidermidis were resistant to cephalosporins and oxacillin. Approximately half of the GNB isolates (34, 51.5%) were multi-drug resistant organisms (MDRO), and 16.7% (11 isolates) were difficult-to-treat resistance (DTR). Furthermore, 68.4% (39 isolates) of GPB were MDRO. The proportion of staphylococci (CoNS and S. aureus) resistant to oxacillin was 91.7%, while 88.6% of enterococci were resistant to vancomycin.

CONCLUSIONS

The findings of this study confirm the predominant microorganisms seen in patients with hematologic malignancies, and show a high percentage of antibiotic resistance. Policies regarding antibiotic use and proper infection control measures are needed to avert the ever-growing danger of antimicrobial resistance. This may be achieved by developing antibiotic stewardship programs and local guidelines based on the hospital's antibiogram.

Approach to fever in patients with neutropenia: a review of diagnosis and management

Febrile neutropenia (FN) is associated with mortality rates as high as 40%, highlighting the importance of appropriate clinical management in this patient population. The morbidity and mortality of FN can be attributed largely to infectious processes, with specific concern for infections caused by pathogens with antimicrobial resistance. Expeditious identification of responsible pathogens and subsequent initiation of empiric antimicrobial therapy is imperative. There are four commonly used guidelines, which have variable recommendations for empiric therapy in these populations. All agree that changes could be made once patients are stable and/or with an absolute neutrophil count (ANC) over 500 cells/mcL. Diagnostic advances have the potential to improve knowledge of pathogens responsible for FN and decrease time to results. In addition, more recent data show that rapid de-escalation or discontinuation of empiric therapy, regardless of ANC, may reduce days of therapy, adverse effects, and cost, without affecting clinical outcomes. Antimicrobial and diagnostic stewardship should be performed to identify, utilize, and respond to appropriate rapid diagnostic tests that will aid in the definitive management of this population.

Surgical and remote site infections after reconstructive surgery of the head and neck: A risk factor analysis

The aim of this study was to identify risk factors for surgical (SSI) and remote site (RSI) infections, pathogens and antibiotic resistances in patients after pedicled and free flap reconstruction in the head and neck area. SSI criteria implicated infections affecting superficial or deep tissue in the flap area with purulent discharge, fistula, abscess formation and local infections signs. RSI criteria were defined as infections remote from the surgical site presenting with systemic symptoms like fever, leucocytosis, increase in C-reactive protein, purulent tracheobronchial secretion or deterioration of blood gases. Focus adequate specimen sampling and aerobic and anaerobic incubation and cultivation was performed. Epidemiological data, factors directly related to surgery or reconstruction, perioperative antibiotic regimen, length of stay, autologous blood transfusion and microbiological aspects were retrospectively analysed in 157 patients. 10.8% of patients presented SSI, 12.7% RSI. Cultivated bacteria were sampled from flap sites, blood cultures, central catheters and sputum including mainly gram-negative bacteria (70.3%) being frequently resistant against penicillin (85%) and third generation cephalosporine derivates (48%). Autologous blood transfusion (p = 0.018) and perioperative clindamycin use (p = 0.002) were independent risk factors for overall (SSI and RSI combined) infections. Prior radiation (p = 0.05), autologous blood transfusion (p = 0.034) and perioperative clindamycin use (p = 0.004) were predictors for SSIs. ASA >2 (p = 0.05) was a risk factor for remote site infections and prolonged ICU stay (p = 0.002) was associated with overall infections, especially in irradiated patients. Efforts need to be made in improving patient blood management, antibiotic stewardship and accurate postoperative care to avoid postoperative infections after head and neck reconstructive surgery.

Administration of a β-lactam Prior to Vancomycin as the First Dose of Antibiotic Therapy Improves Survival in Patients with Bloodstream Infections

OBJECTIVE

Prompt initiation of antibiotic therapy improves the survival of patients with bloodstream infections (BSI). We sought to determine if the sequence of administration of the first dose of antibiotic therapy (i.e., β-lactam or vancomycin, if both cannot be administered simultaneously) impacts early mortality for patients with BSI.

METHODS

We conducted a multicenter, observational study of patients ≥13 years with BSIs to evaluate the association of the sequence of antibiotic administration with 7-day mortality using inverse probability of treatment weighting (IPTW) incorporating propensity scores. Propensity scores were generated based on: demographics, Pitt bacteremia score, ICU status, highest lactate, highest WBC count, Charlson Comorbidity index, severe immunocompromise, administration of active empiric therapy, combination therapy, and time from emergency department arrival to first antibiotic dose.

RESULTS

Of 3,376 eligible patients, 2,685 (79.5%) received a β-lactam and 691 (20.5%) received vancomycin as their initial antibiotic. In the IPTW cohort, exposed and unexposed patients were similar on all baseline variables. Administration of a β-lactam agent prior to vancomycin protected against 7-day mortality (aOR 0.48 (95% CI: 0.33-0.69)]. Similar results were observed when evaluating 48-hour mortality (aOR 0.45 [95% CI: 0.24-0.83]). Administration of vancomycin prior to a β-lactam was not associated with improved survival in the subgroup of 524 patients with methicillin-resistant Staphylococcus aureus BSI (aOR 0.93 [95% CI: 0.33-2.63]).

CONCLUSIONS

For ill-appearing patients likely to be experiencing a BSI, prioritizing administration of a β-lactam over vancomycin may reduce early mortality, underscoring the significant impact of a relatively simple practice change on improving patient survival.

Secondary Infections After Diagnosis of Severe Radiation Pneumonitis (SRP) Among Patients With Non-small Cell Lung Cancer: Pathogen Distributions, Choice of Empirical Antibiotics, and the Value of Empirical Antifungal Treatment

PURPOSE

This study aimed to assess pathogen distributions and antimicrobial sensitivity characteristics in patients with non-small cell lung cancer (NSCLC) with severe radiation pneumonitis (SRP) and secondary infections.

METHODS AND MATERIALS

Data from 1746 patients with NSCLC and SRP after thoracic radiation therapy from January 2009 to December 2020 were retrospectively analyzed. Pneumonia incidence, causative pathogens, and antibiotic resistance characteristics in patients with secondary lung infections were analyzed. Risk factors associated with mortality were identified through univariate and multivariate analyses. Antifungal drug efficacy and duration-related effects were assessed with Forest plots and receiver operating characteristic curves.

RESULTS

Overall, 44.5% of patients with NSCLC and SRP (777 of 1746 patients) were diagnosed with secondary lung infections. In total, 899 bacterial strains were isolated from these patients, with Acinetobacter baumannii (n = 206; 27%), Klebsiella pneumonia (n = 200; 26.2%), and Pseudomonas aeruginosa (n = 104; 13.6%) being the most common. Carbapenems and cefoperazone-sulbactam resistance rates of 52.7% and 32.2%, 28.8% and 26.4%, and 23.7% and 20.2% were observed for these isolates, respectively. Infection-related deaths occurred in 22.4% of patients with SRP. Independent risk factors for infection-related death included poor performance status scores, inappropriate empirical antimicrobial treatment, bacteria/fungal coinfection, and lack of empirical antifungal treatment. Receiver operating characteristic curves showed that the cutoff value of empirical antifungal treatment duration was 9 (area under the curve: 0.819).

CONCLUSIONS

For patients with SRP and secondary lung infections, appropriate empirical antimicrobial treatment could decrease infection-related mortality, and cefoperazone-sulbactam may be an appropriate antibacterial drug. Empirical antifungal treatment for a minimum of 9 days might contribute to better outcomes. Although this represents a promising treatment approach for patients with SRP and secondary lung infections before antibacterial susceptibility testing, further prospective validation is essential.

Development of potent antipseudomonal β-lactams by means of polycarboxylation of aminopenicillins

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that presents a serious risk to immunosuppressed individuals and other extremely vulnerable patients such as those in intensive care units. The emergence of multidrug-resistant Pseudomonas strains has increased the need for new antipseudomonal agents. In this study, a series of amino group-modified aminopenicillin derivatives was synthesized that have different numbers of carboxyl groups and structurally resemble carboxypenicillin-ureidopenicillin hybrids, and their antipseudomonal activities were evaluated. Among the derivatives synthesized, diethylenetriaminepentaacetic acid (DTPA)-modified amoxicillin (DTPA-Amox) showed potent antipseudomonal activity, not only against the laboratory strain PAO1 but also against clinically isolated Pseudomonas strains that were resistant to piperacillin and carbenicillin. DTPA-Amox had no obvious cytotoxic effects on cultured mammalian cells. In addition, in an in vivo model of leukopenia, DTPA-Amox treatment produced a moderate but statistically significant improvement in the survival of mice with P. aeruginosa strain PAO1 infection. These data suggest that polycarboxylation by DTPA conjugation is an effective approach to enhance antipseudomonal activity of aminopenicillins.

Predictive and risk factor analysis for bloodstream infection in high-risk hematological patients with febrile neutropenia: post-hoc analysis from a prospective, large-scale clinical study

OBJECTIVES

Bloodstream infection (BSI) is a frequent complication observed in patients with febrile neutropenia (FN). BSI risk factors and incidence vary depending on chemotherapy types and prophylactic antimicrobial agents. We clarified these issues by post-hoc analysis of a prospective clinical trial cohort for severe FN in hematological malignancy.

METHODS

We performed an intention-to-treat analysis of 413 high-risk patients and 1272 blood culture sets.

RESULTS

Overall, 356 patients (86.2%) developed FN, and 20.8% had BSI complications. Prophylactic antimicrobials did not prevent complications of FN and BSI, but the incidence of BSIs of Gram-negative (GN) bacteria was lower than in the non-prophylaxis group (23.8% vs. 56.7%). Multinational Association of Supportive Care in Cancer (MASCC) scores < 20 were significantly correlated with the incidence of BSI, whereas MASCC scores > 21 were not (41.7% vs. 17.2%). The only significant risk factors were hypotension and dehydration. axillary temperatures were higher in GN-caused BSIs than in Gram-positive-caused BSIs and in patients with negative blood culture results (38.7 °C vs. 38.2 °C vs. 38.0 °C). The higher the fever, the higher the incidence of BSI and GN bacteremia.

CONCLUSIONS

MASCC score and axillary temperature are strong predictors of BSI. Non-administration of prophylactic antimicrobials and GN-caused BSI are correlated.

THE CLINICAL TRIAL REGISTRATION NUMBER

UMIN00010411.

Short-Course Versus Long-Course Colistin for Treatment of Carbapenem-Resistant A.baumannii in Cancer Patient

Carbapenem-resistant Acinetobacter baumannii (CRAB) is one of the most commonly reported nosocomial infections in cancer patients and could be fatal because of suboptimal immune defenses in these patients. We aimed to compare clinical response, microbiological response, nephrotoxicity, and 30-day mortality between cancer patients who received short (<14 days) and long (≥14 days) courses of colistin for treatment of CRAB infection. A retrospective cohort study was conducted in cancer patients with CRAB infection who received short or long courses of colistin between 2015 to 2017 at Chiang Mai University Hospital (CMUH). A total of 128 patients met the inclusion criteria. The results of this study show that patients who received long course of colistin therapy had a higher rate of clinical response; adjusted odds ratio (OR) was 3.16 times in patients receiving long-course colistin therapy (95%CI, 1.37–7.28; p value = 0.007). Microbiological response in patients with long course was 4.65 times (adjusted OR) higher than short course therapy (95%CI, 1.72–12.54; p value = 0.002). Moreover, there was no significant difference in nephrotoxicity (adjusted OR, 0.91, 95%CI, 0.39–2.11; p value = 0.826) between the two durations of therapy. Thirty-day mortality in the long-course therapy group was 0.11 times (adjusted OR) compared to the short-course therapy group (95%CI, 0.03–0.38; p value = 0.001). Propensity score analyses also demonstrated similar results. In conclusion, cancer patients who received a long course of colistin therapy presented greater clinical and microbiological responses and lower 30-day mortality but similar nephrotoxicity as compared with those who a received short course. Therefore, a long course of colistin therapy should be considered for management of CRAB infection in cancer patients.

Bacterial Profile and Antibiotic Resistance among Cancer Patients with Urinary Tract Infection in a National Tertiary Cancer Hospital of Nepal

Cancer patients are at high risk of antibiotic resistant bacterial urinary tract infections (UTIs). In this study, we assessed the bacterial profile and antibiotic resistance among cancer patients suspected of UTI in B.P. Koirala Memorial Cancer Hospital in Nepal through a cross-sectional study with routinely collected data. All cancer patients who had a recorded urine culture between July 2018-June 2019 were included in the study. Out of 308 patients who had undergone culture, 73 (24%) of samples had bacterial growth. The most common organisms isolated were E. coli (58%), Staphylococcus (11%) and Klebsiella (10%). These bacteria had undergone susceptibility testing to 27 different antibiotics in various proportions. Of the limited antibiotic testing levels, nitrofurantoin (54/66, 82%) and amikacin (30/51, 59%) were the most common. Among those tested, there were high levels of resistance to antibiotics in the "Access" and "Watch" groups of antibiotics (2019 WHO classification). In the "Reserve" group, both antibiotics showed resistance (polymyxin 15%, tigecycline 8%). Multidrug resistance was seen among 89% of the positive culture samples. This calls for urgent measures to optimize the use of antibiotics in UTI care at policy and health facility levels through stewardship to prevent further augmentation of antibiotic resistance among cancer patients.

Silencing Antibiotic Resistance with Antisense Oligonucleotides

Antisense technologies consist of the utilization of oligonucleotides or oligonucleotide analogs to interfere with undesirable biological processes, commonly through inhibition of expression of selected genes. This field holds a lot of promise for the treatment of a very diverse group of diseases including viral and bacterial infections, genetic disorders, and cancer. To date, drugs approved for utilization in clinics or in clinical trials target diseases other than bacterial infections. Although several groups and companies are working on different strategies, the application of antisense technologies to prokaryotes still lags with respect to those that target other human diseases. In those cases where the focus is on bacterial pathogens, a subset of the research is dedicated to produce antisense compounds that silence or reduce expression of antibiotic resistance genes. Therefore, these compounds will be adjuvants administered with the antibiotic to which they reduce resistance levels. A varied group of oligonucleotide analogs like phosphorothioate or phosphorodiamidate morpholino residues, as well as peptide nucleic acids, locked nucleic acids and bridge nucleic acids, the latter two in gapmer configuration, have been utilized to reduce resistance levels. The major mechanisms of inhibition include eliciting cleavage of the target mRNA by the host’s RNase H or RNase P, and steric hindrance. The different approaches targeting resistance to β-lactams include carbapenems, aminoglycosides, chloramphenicol, macrolides, and fluoroquinolones. The purpose of this short review is to summarize the attempts to develop antisense compounds that inhibit expression of resistance to antibiotics.

Simple Secondary Amines Inhibit Growth of Gram-Negative Bacteria through Highly Selective Binding to Phenylalanyl-tRNA Synthetase

Antibiotics to treat drug-resistant Gram-negative infections are urgently needed but challenging to discover. Using a cell-based screen, we identified a simple secondary amine that inhibited the growth of wild-type Escherichia coli and Acinetobacter baumannii but not the growth of the Gram-positive organism Bacillus subtilis. Resistance mutations in E. coli and A. baumannii mapped exclusively to the aminoacyl-tRNA synthetase PheRS. We confirmed biochemically that the compound inhibited PheRS from these organisms and showed that it did not inhibit PheRS from B. subtilis or humans. To understand the basis for the compound's high selectivity for only some PheRS enzymes, we solved crystal structures of E. coli and A. baumannii PheRS complexed with the inhibitor. The structures showed that the compound's benzyl group mimics the benzyl of phenylalanine. The other amine substituent, a 2-(cyclohexen-1-yl)ethyl group, induces a hydrophobic pocket in which it binds. Through bioinformatic analysis and mutagenesis, we show that the ability to induce a complementary hydrophobic pocket that can accommodate the second substituent explains the high selectivity of this remarkably simple molecular scaffold for Gram-negative PheRS. Because this secondary amine scaffold is active against wild-type Gram-negative pathogens but is not cytotoxic to mammalian cells, we suggest that it may be possible to develop it for use in combination antibiotic therapy to treat Gram-negative infections.

Microbiological Profile of Blood Stream Infections in Febrile Neutropenic Patients at a Tertiary Care Teaching Hospital in Rishikesh, Uttarakhand

Context  Febrile neutropenia is a serious complication of chemotherapy affecting patients with both hematological and solid malignancies, respectively. To the best of our knowledge, there is paucity of literature from Uttarakhand, India on microbiological profile of blood stream infections (BSIs) in febrile neutropenic patients. Aims  The study aims to generate preliminary data on microbiological profile and antibiotic resistance pattern of BSIs in febrile neutropenic patients. Settings and Design   The design involved cross-sectional study from January 1, 2019 to July 31, 2019. Methods and Materials  Data of nonrepetitive paired peripheral blood samples obtained from 306 consecutive febrile neutropenic cancer patients of all age groups and both sexes, for culture and sensitivity testing, were retrospectively analyzed. All blood samples were subjected to aerobic culture using BACT/ALERT three-dimensional microbial detection system. Growth obtained in culture was identified by conventional biochemical methods. Antibiotic susceptibility testing of bacterial isolates was performed using modified Kirby Bauer disk diffusion method. Statistical Analysis Used   Fisher's exact test was used for the analysis. Results  Mean age ± SD of the study population was 32.39 ± 10.56 years with a male to female ratio of 1.55:1. 74.18% of the blood samples were received from patients suffering from hematological malignancies. Microbiologically confirmed BSIs were observed in 27.1% patients. Gram-negative bacilli were predominantly isolated in culture with Klebsiella spp . being the most common. Percentage resistance values of gram-negative bacilli to aminoglycosides, β-lactam/β-lactamase inhibitor combinations, fluoroquinolones, cephalosporins, carbapenems, chloramphenicol, ampicillin, co-trimoxazole, and doxycycline were 26.6 to 91.7%, 8.3 to 86.6%, 10 to 66.7%, 13.3 to 73.3%, 8.3 to 73.3%, 80 to 93.3%, 13.3 to 20%, 16.7 to 66.6%, and 13.3 to 16.7%, respectively. Conclusion  Implementation of antimicrobial stewardship program along with hospital infection control practices is needed for preventing BSIs due to MDR organisms.

Polymyxins-Curcumin Combination Antimicrobial Therapy: Safety Implications and Efficacy for Infection Treatment

The emergence of antimicrobial resistance in Gram-negative bacteria poses a huge health challenge. The therapeutic use of polymyxins (i.e., colistin and polymyxin B) is commonplace due to high efficacy and limiting treatment options for multidrug-resistant Gram-negative bacterial infections. Nephrotoxicity and neurotoxicity are the major dose-limiting factors that limit the therapeutic window of polymyxins; nephrotoxicity is a complication in up to ~60% of patients. The emergence of polymyxin-resistant strains or polymyxin heteroresistance is also a limiting factor. These caveats have catalyzed the search for polymyxin combinations that synergistically kill polymyxin-susceptible and resistant organisms and/or minimize the unwanted side effects. Curcumin—an FDA-approved natural product—exerts many pharmacological activities. Recent studies showed that polymyxins–curcumin combinations showed a synergistically inhibitory effect on the growth of bacteria (e.g., Gram-positive and Gram-negative bacteria) in vitro. Moreover, curcumin co-administration ameliorated colistin-induced nephrotoxicity and neurotoxicity by inhibiting oxidative stress, mitochondrial dysfunction, inflammation and apoptosis. In this review, we summarize the current knowledge-base of polymyxins–curcumin combination therapy and discuss the underlying mechanisms. For the clinical translation of this combination to become a reality, further research is required to develop novel polymyxins–curcumin formulations with optimized pharmacokinetics and dosage regimens.

Pharmacokinetics and Efficacy of Ceftazidime-Avibactam in the Treatment of Experimental Pneumonia Caused by Klebsiella pneumoniae Carbapenemase-Producing K. pneumoniae in Persistently Neutropenic Rabbits

Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) is an emerging global public health threat that causes life-threatening pneumonia and bacteremia. Ceftazidime-avibactam (CZA) represents a promising advance for the treatment of serious infections caused by KPC-Kp We investigated the pharmacokinetics and efficacy of ceftazidime-avibactam in the treatment of experimental KPC-Kp pneumonia in persistently neutropenic rabbits. For single-dose and multidose (administration every 8 h) pharmacokinetics, rabbits received ceftazidime-avibactam intravenous infusions at 60/15, 90/22.5, and 120/30 mg/kg of body weight. Ceftazidime mean area under the concentration-time curves (AUCs) ranged from 287 to 608 μg·h/ml for a single dose and from 300 to 781 μg·h/ml for multiple doses. Avibactam AUCs ranged from 21 to 48 μg·h/ml for a single dose and from 26 to 48 μg·h/ml for multiple doses. KPC-Kp pneumonia was established by direct endotracheal inoculation. Treatments consisted of ceftazidime-avibactam at 120/30 mg/kg every 6 h, a polymyxin B (PMB) loading dose of 2.5 mg/kg followed by 1.5 mg/kg every 12 h q12h, or no treatment (untreated controls [UC]). There were significant reductions in the residual bacterial burden, lung weights, and pulmonary hemorrhage scores in CZA- and PMB-treated rabbits for a 7-day or a 14-day (P ≤ 0.01) course in comparison with those in the UC. These results corresponded to significant decreases in the bacterial burden in bronchoalveolar lavage fluid after a 7-day or a 14-day treatment (P ≤ 0.01). The outcomes demonstrated an improved response at 14 days versus that at 7 days. There was significantly prolonged survival in rabbits treated with CZA for 14 days in comparison with that in the PMB-treated or UC rabbits (P ≤ 0.05). This study demonstrates that ceftazidime-avibactam displays linear dose-proportional exposures simulating those seen from human plasma pharmacokinetic profiles, is active for the treatment of experimental KPC-Kp pneumonia in persistently neutropenic rabbits, and provides an experimental foundation for the treatment of severely immunocompromised patients with this life-threatening infection.

Febrile Neutropenia in Acute Leukemia. Epidemiology, Etiology, Pathophysiology and Treatment

Acute leukemias are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. An important cause of both the latter is infectious complications. Patients with acute leukemia are highly susceptible to infectious diseases due to factors related to the disease itself, factors attributed to treatment, and specific individual risk factors in each patient. Patients with chemotherapy-induced neutropenia are at particularly high risk, and microbiological agents include viral, bacterial, and fungal agents. The etiology is often unknown in infectious complications, although adequate patient evaluation and sampling have diagnostic, prognostic and treatment-related consequences. Bacterial infections include a wide range of potential microbes, both Gram-negative and Gram-positive species, while fungal infections include both mold and yeast. A recurring problem is increasing resistance to antimicrobial agents, and in particular, this applies to extended-spectrum beta-lactamase resistance (ESBL), Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and even carbapenemase-producing Enterobacteriaceae (CPE). International guidelines for the treatment of sepsis in leukemia patients include the use of broad-spectrum Pseudomonas-acting antibiotics. However, one should implant the knowledge of local microbiological epidemiology and resistance conditions in treatment decisions. In this review, we discuss infectious diseases in acute leukemia with a major focus on febrile neutropenia and sepsis, and we problematize the diagnostic, prognostic, and therapeutic aspects of infectious complications in this patient group. Meticulously and thorough clinical and radiological examination combined with adequate microbiology samples are cornerstones of the examination. Diagnostic and prognostic evaluation includes patient review according to the multinational association for supportive care in cancer (MASCC) and sequential organ failure assessment (SOFA) scoring system. Antimicrobial treatments for important etiological agents are presented. The main challenge for reducing the spread of resistant microbes is to avoid unnecessary antibiotic treatment, but without giving to narrow treatment to the febrile neutropenic patient that reduce the prognosis.

Proposal of a clinical score to stratify the risk of multidrug-resistant gram-negative rods bacteremia in cancer patients

Introduction

Multidrug-resistant gram-negative rods (MDR GNR) represent a growing threat for patients with cancer. Our objective was to determine the characteristics of and risk factors for MDR GNR bacteremia in patients with cancer and to develop a clinical score to predict MDR GNR bacteremia.

Material and Methods

Multicenter prospective study analyzing initial episodes of MDR GNR bacteremia. Risk factors were evaluated using a multiple logistic regression (forward-stepwise selection) analysis including variables with a p < 0.10 in univariate analysis.

Results

394 episodes of GNR bacteremia were included, with 168 (42.6 %) being MDR GNR. Five variables were identified as independent risk factors: recent antibiotic use (OR = 2.8, 95 % CI 1.7–4.6, p = 0.001), recent intensive care unit admission (OR = 2.9, 95 % CI 1.1–7.8, p = 0.027), hospitalization ≥ 7 days prior to the episode of bacteremia (OR = 3.5, 95 % CI 2–6.2, p = 0.005), severe mucositis (OR = 5.3, 95 % CI 1.8–15.6, p = 0.002), and recent or previous colonization/infection with MDR GNR (OR = 2.3, 95 % CI 1.2–4.3, p = 0.028). Using a cut-off value of two points, the score had a sensitivity of 66.07 % (95 % CI 58.4–73.2 %), a specificity of 77.8 % (95 % CI 71.4–82.7 %), a positive predictive value of 68 % (95 % CI 61.9–73.4 %), and a negative predictive value of 75.9 % (95 % CI 71.6–79.7 %). The overall performance of the score was satisfactory (AUROC 0.78; 95 % CI 0.73-0.82). In the cases with one or none of the risk factors identified, the negative likelihood ratio was 0.18 and the post-test probability of having MDR GNR was 11.68 %.

Conclusions

With the growing incidence of MDR GNR as etiologic agents of bacteremia in cancer patients, the development of this score could be a potential tool for clinicians.

Aztreonam and Vancomycin for Initial Treatment of Febrile Neutropenia in Penicillin-Allergic Patients During Hematopoietic Stem Cell Transplantation

Most patients who undergo hematopoietic stem cell transplantation develop neutropenic fever and are at high risk for developing potentially life-threatening infections. β-lactam antibiotics remain the cornerstone for initial empiric treatment of neutropenic fever. In cancer patients with allergy or intolerance to β-lactams, guidelines recommend using aztreonam with vancomycin (AV) for neutropenic fever treatment. To date, the efficacy of AV for the treatment of neutropenic fever during stem cell transplantation is unknown. A retrospective study was conducted to identify hematopoietic stem cell transplantation recipients who were initially treated with concomitant AV for neutropenic fever between 2007 and 2013. Febrile neutropenia was classified as neutropenia with unexplained fever, neutropenic fever with a local source of infection, or neutropenic fever with a microbiologically documented infection. Seventy-six patients were identified who received AV as initial treatment for neutropenic fever over the study period. Responses to AV for neutropenia with unexplained fever (n = 41), febrile neutropenia with local site of infection (n = 11 [pneumonia = 9, other = 2]), and neutropenic fever with microbiologically documented infection (n = 34) were 75%, 55% (45% pneumonia), and 46% respectively. Infection-related mortality was 5%. Aztreonam with vancomycin was effective in treating neutropenia with unexplained fever. For patients with neutropenic fever and local source or microbiologically documented infection, alternative antibiotic treatments should be considered.

Ceftolozane-Tazobactam in the Treatment of Experimental Pseudomonas aeruginosa Pneumonia in Persistently Neutropenic Rabbits: Impact on Strains with Genetically Defined Mechanisms of Resistance

Ceftolozane-tazobactam (C/T) is a novel cephalosporin with in vitro activity against Pseudomonas aeruginosa that is resistant to extended-spectrum penicillins and antipseudomonal cephalosporins. In order to assess the antimicrobial effect of C/T in treatment of Pseudomonas pneumonia, we investigated the pharmacokinetics and efficacy of C/T in persistently neutropenic rabbits. Pseudomonas pneumonia was established by direct endotracheal inoculation. Treatment groups consisted of C/T, ceftazidime (CAZ), piperacillin-tazobactam (TZP), and untreated controls (UC). Rabbits received a dosage of C/T of 80 mg/kg every 4 h (q4h) intravenously (i.v.) (53 mg/kg ceftolozane/26 mg/kg tazobactam) to match the free drug time above the MIC as well as a comparable plasma area under the concentration-time curve (AUC) (humanized doses of ceftolozane-tazobactam of 3 g [2 g/1 g]) q8h, due to the more rapid elimination of ceftolozane in rabbits (0.75 h) than in humans (2.5 h). Four molecularly characterized clinical P. aeruginosa isolates from patients with pneumonia were studied, including one isolate from each classification group: pan-susceptible (PS), outer membrane porin D (OPRD) porin loss (OPRDPL), efflux pump expression (EPE), and AmpC hyperexpression (ACHE). Treatment was continued for 12 days. Treatment with ceftolozane-tazobactam resulted in a ≥10⁵ reduction in residual pulmonary and bronchoalveolar lavage (BAL) fluid bacterial burdens caused by all 4 strains (P ≤ 0.01). This antibacterial activity coincided with reduction of lung weight (an organism-mediated pulmonary injury marker) (P < 0.05). CAZ was less active in ACHE-infected rabbits, and TZP had less activity against EPE, ACHE, and OPRDPL strains. Survival was prolonged in the C/T and CAZ treatment groups in comparison to the TZP and UC groups (P < 0.001). Ceftolozane-tazobactam is highly active in treatment of experimental P. aeruginosa pneumonia in persistently neutropenic rabbits, including infections caused by strains with the most common resistance mechanisms.

Osteomyelitis Caused by Carbapenemase-Producing Klebsiella Pneumoniae: A Diagnosis to Consider in Patients with Hematologic Malignancies and Stem Cell Transplant Recipients

Case series

Patients: Female, 49 • Female, 47

Final Diagnosis: Osteomyelitis by Klebsiella pneumoniae

Symptoms: Fever

Medication: —

Clinical Procedure: —

Specialty: Hematology

Pattern of Antimicrobial Sensitivity in Microbiologically Documented Infections in Neutropenic Patients with Haematological Malignancies: A single Center Study

Febrile neutropenia is a medical emergency that complicates the clinical course and treatment of haematological malignancies, significantly enhancing the financial burden and worsening the overall outcome. This study was carried out to evaluate the efficacy of institution's current first-line antibiotic regimen for febrile neutropenia in view of recent spectrum of institution's local flora and its susceptibility pattern. 163 episodes of microbiologically documented infections in 110 adult patients were studied over a period of 1 year. Of 110 patients, 61 patients were male. The mean age of the patient population, mean absolute neutrophil count and temperature as documented were 30.1 years (SD ± 16.8), 450 cells/ul, and 101.9 °C respectively. Gram-negative and gram-positive organisms accounted for 79% and 21% of the febrile neutropenic infections respectively. E. coli and Staphylococcus aureus were the most common gram positive and gram negative pathogens respectively. A susceptibility pattern of > 60% was documented for all the gram negative pathogen's associated febrile neutropenic infections for the current first-line antibiotic combination of Piperacillin/Tazobactum and Amikacin. Comparative analysis of results with the institutional data of 2015 study revealed no statistically significant difference in the resistance pattern of the organisms hence, validating the persistent use of Piperacillin/Tazobacum and Amikacin combination as a potent and efficacious therapy for febrile neutropenia patients with haematological malignancies. However, continuous surveillance remains prudent for the emerging changes in the spectrum and resistance pattern of local flora so that timely revision of empirical antibiotic regimens can save the added financial burdens and associated high morbidity and mortality.

High-risk medication use for Clostridium difficile infection among hospitalized patients with cancer

Patients with cancer are vulnerable to Clostridium difficile infection (CDI); hospitals with larger oncology populations may have worse CDI performance. Among 71 academic hospitals studied, there were significant differences in oncology patient-days per 1,000 admissions across CDI standardized infection ratio categories of better, no different, and worse; worse hospitals had the greatest number of patient-days. Oncology patients' most commonly used high-risk CDI medications were quinolones, third- and fourth-generation cephalosporins, and proton pump inhibitors.

Molecular Mechanisms of Neurotoxicity Induced by Polymyxins and Chemoprevention

Neurotoxicity is one major unwanted side-effects associated with polymyxin (i.e., colistin and polymyxin B) therapy. Clinically, colistin neurotoxicity is characterized by neurological symptoms including dizziness, visual disturbances, vertigo, confusion, hallucinations, seizures, ataxia, and facial and peripheral paresthesias. Pathologically, colistin-induced neurotoxicity is characterized by cell injury and death in neuronal cell. This Review covers our current understanding of polymyxin-induced neurotoxicity, its underlying mechanisms, and the discovery of novel neuroprotective agents to limit this neurotoxicity. In recent years, an increasing body of literature supports the notion that polymyxin-induced nerve damage is largely related to oxidative stress and mitochondrial dysfunction. P53, PI3K/Akt, and MAPK pathways are also involved in colistin-induced neuronal cell death. The activation of the redox homeostasis pathways such as Nrf2/HO-1 and autophagy have also been shown to play protective roles against polymyxin-induced neurotoxicity. These pathways have been demonstrated to be upregulated by neuroprotective agents including curcumin, rapamycin and minocycline. Further research is needed toward the development of novel polymyxin formulations in combination with neuroprotective agents to ameliorate this unwanted adverse effect during polymyxins therapy in patients.