Evolution of blaKPC Under the Pressure of Carbapenems and Ceftazidime/Avibactam in a Patient With Persistent Bacteremia Caused by Klebsiella pneumoniae.

A 30-year-old Korean man with myelodysplastic syndrome admitted hospital due to undifferentiated fever and recurrent skin lesions. He received combination therapy with high doses of meropenem, tigecycline and amikacin, yielding carbapenem resistant Klebsiella pneumoniae (CRKP) harboring K. pneumoniae carbapenemase (KPC)-2 from blood cultures on hospital day (HD) 23. Ceftazidime/avibactam was started at HD 37 and CRKP was eradicated from blood cultures after 5 days. However, ceftazidime/avibactam-resistant CRKP carrying KPC-44 emerged after 26 days of ceftazidime/avibactam treatment and then ceftazidime/avibactam-resistant, carbapenem-susceptible K. pneumoniae carrying KPC-135 was isolated on HD 65. The 3-D homology of KPC protein showed that hot spot changes in the omega loop could be attributed to ceftazidime/avibactam resistance and loss of carbapenem resistance. Whole genome sequencing of serial isolates supported that phenotypic variation was due to clonal evolution than clonal replacement. The treatment regimen was changed from CAZ/AVI to meropenem-based therapy (meropenem 1 g iv q 8 hours and amikacin 600 mg iv per day) starting with HD 72. CAZ/AVI-susceptible CRKP was presented again from blood cultures on HD 84, and the patient expired on HD 85. This is the first Korean report on the acquisition of ceftazidime/avibactam resistance through the emergence of blaKPC variants.

Butyricimonas faecihominis: an atypically resistant bacterium implicated in abscess formation - a case report.

BACKGROUND: This case report presents a unique instance of abscesses with an uncommon pathogen isolated from blood cultures. CASE PRESENTATION: We present the case of a perianal abscess in a 50-year-old man with a history of cocaine abuse and bilateral hip replacements. The rapid progression led to septic shock and multi-organ failure, requiring intensive care unit admission, surgery including protective transversostomy. Blood cultures showed growth of Butyricimonas spp. with resistance to penicillin and piperacillin-tazobactam. The immediate switch to meropenem led to a significant improvement in the patient's condition. The patient was discharged after 40 days of hospitalization in good general condition and the reversal of the transversostomy was performed six months later. CONCLUSION: The identification of Butyricimonas faecihominis, a rarely reported pathogen, emphasizes the challenges of diagnosing and treating unusual infections. This case emphasizes the importance of rapid microbiological diagnosis, interdisciplinary collaboration, and targeted antibiotic therapy in the treatment of abscesses and sepsis.

Bacteriological profile, antimicrobial susceptibility, and factors associated with urinary tract infection in pregnant women.

INTRODUCTION: Urinary tract infection (UTI) is a common bacterial complication in pregnancy. The study aimed to estimate the prevalence, risk factors, and bacterial etiology of UTI during pregnancy and determine the efficacy of antimicrobial drugs in treating UTIs. METHODOLOGY: Urine specimens and clinical data were collected from pregnant women who attended primary health centers in Erbil, Iraq. All specimens were cultured on appropriate media and identified by standard microbiological methods. The pregnant women were grouped into symptomatic UTI group, asymptomatic bacteriuria group, and the control group. The agar dilution method was used to determine antimicrobial susceptibility. RESULTS: Among the 5,042 pregnant women included in this study, significant bacteriuria was found in 625 (12.40%) of the cases, and 198 (31.68%) had symptomatic UTI, of which 43.59% were diagnosed during the third trimester. Out of the 643 bacteria isolated, 33.28% were symptomatic UTI, of which 43.59% developed during the third trimester. There was a significant difference in the bacterial etiology between symptomatic UTI and asymptomatic bacteriuria (p = 0.002), as well as between cystitis and pyelonephritis (p = 0.017). The most common bacterial species isolated was Escherichia coli, which was susceptible to fosfomycin (100%), meropenem (99.45%), and nitrofurantoin (97.8%). CONCLUSIONS: Pregnant women are more likely to develop UTI in the third trimester. Escherichia coli is the predominant pathogen. The study suggests the use of fosfomycin, meropenem, and nitrofurantoin for the treatment of UTI. No Gram-positive isolates were resistant to daptomycin.

A case report on rapid development of simultaneous liver and musculature calcifications in severe sepsis.

A 76-year-old Malay female presented with 2 days history of fever and vomiting. She was found to have Escherichia coli and Klebsiella pneumoniae bacteraemia with no clear intra-abdominal cause on the initial computed tomography of the abdomen and pelvis (CTAP). She clinically improved with 2 weeks duration of intravenous meropenem. She subsequently developed septic shock and a repeated CTAP demonstrated increased hepatic parenchymal density with extensive parenchymal calcifications. Curvilinear calcifications were seen in the paraspinal and pelvic musculature.

Cost-effectiveness analysis of CTZ/TAZ for the treatment of ventilated hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia in Japan.

BACKGROUND: Resistant bacterial infections, particularly those caused by gram-negative pathogens, are associated with high mortality and economic burdens. Ceftolozane/tazobactam demonstrated efficacy comparable to meropenem in patients with ventilated hospital-acquired bacterial pneumonia in the ASPECT-NP study. One cost-effectiveness analysis in the United States revealed that ceftolozane/tazobactam was cost effective, but no Japanese studies have been conducted. Therefore, the objective of this study was to assess the cost-effectiveness of ceftolozane/tazobactam compared to meropenem for patients with ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia from a health care payer perspective. METHODS: A hybrid decision-tree Markov decision-analytic model with a 5-year time horizon were developed to estimate costs and quality-adjusted life-years and to calculate the incremental cost-effectiveness ratio associated with ceftolozane/tazobactam and meropenem in the treatment of patients with ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia. Clinical outcomes were based on the ASPECT-NP study, costs were based on the national fee schedule of 2022, and utilities were based on published data. One-way sensitivity analysis and probabilistic sensitivity analysis were also conducted to assess the robustness of our modeled estimates. RESULTS: According to our base-case analysis, compared with meropenem, ceftolozane/tazobactam increased the total costs by 424,731.22 yen (£2,626.96) and increased the quality-adjusted life-years by 0.17, resulting in an incremental cost-effectiveness ratio of 2,548,738 yen (£15,763.94) per quality-adjusted life-year gained for ceftolozane/tazobactam compared with meropenem. One-way sensitivity analysis showed that although the incremental cost-effectiveness ratio remained below 5,000,000 yen (£30,925) for most of the parameters, the incremental net monetary benefit may have been less than 0 depending on the treatment efficacy outcome, especially the cure rate and mortality rate for MEPM and mortality rate for CTZ/TAZ. 53.4% of the PSA simulations demonstrated that CTZ/TAZ was more cost-effective than MEPM was. CONCLUSION: Although incremental cost-effectiveness ratio was below ï¿¥5,000,000 in base-case analysis, whether ceftolozane/tazobactam is a cost-effective alternative to meropenem for ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia in Japan remains uncertain. Future research should examine the unobserved heterogeneity across patient subgroups and decision-making settings, to characterise decision uncertainty and its consequences so as to assess whether additional research is required.

Meropenem versus piperacillin-tazobactam for the treatment of pancreatic necrosis.

PURPOSE: To date, there are three published guidelines discussing management of infected pancreatic necrosis (IPN) with conflicting recommendations. Specifically, The World Society of Emergency Surgery lists piperacillin-tazobactam as a treatment option in addition to meropenem and ciprofloxacin plus metronidazole. Piperacillin-tazobactam may serve as an effective carbapenem-sparing alternative. Although previous studies shed light on antimicrobial penetration data, there is a lack of clinical data comparing piperacillin-tazobactam to meropenem. The purpose of this study is to compare the efficacy of meropenem and piperacillin-tazobactam for the treatment of IPN. METHODS: This was a multicenter, retrospective cohort study conducted across three institutions. Patients with IPN who received either meropenem or piperacillin-tazobactam from January 2015 to December 2020 were included. The primary composite outcome was the incidence of 90-day clinical failure, which encompassed 90-day all-cause mortality and 90-day intra-abdominal infection recurrence. Secondary outcomes included length of hospital stay, antimicrobial duration of therapy, and the need for surgical intervention. RESULTS: We identified 229 patients with IPN that received either meropenem or piperacillin-tazobactam during hospital admission. After screening, 63 patients were included in the study. Incidence of 90-day clinical failure was observed in 33 % of the meropenem group and 50 % in the piperacillin-tazobactam group (OR, 1.98; 95 % CI 0.57 to 7.01, p = 0.259). The meropenem group had a lower incidence of 90-day infection recurrence in the piperacillin-tazobactam group (56 % vs 29 %, p = 0.047). CONCLUSIONS: Piperacillin-tazobactam may be an efficacious carbapenem-sparing treatment alternative for infected pancreatic necrosis.

Metabolomics Method in Understanding and Sensitizing Carbapenem-Resistant Acinetobacter baumannii to Meropenem.

Carbapenem-resistant Acinetobacter baumannii (CRAB) strains are prevalent worldwide and represent a major threat to public health. However, treatment options for infections caused by CRAB are very limited as they are resistant to most of the commonly used antibiotics. Consequently, understanding the mechanisms underlying carbapenem resistance and restoring bacterial susceptibility to carbapenems hold immense importance. The present study used gas chromatography-mass spectrometry (GC-MS)-based metabolomics to investigate the metabolic mechanisms of antibiotic resistance in clinically isolated CRAB. Inactivation of the pyruvate cycle and purine metabolism is the most typical characteristic of CRAB. The CRAB exhibited a reduction in the activity of enzymes involved in the pyruvate cycle, proton motive force, and ATP levels. This decline in central carbon metabolism resulted in a decrease in the metabolic flux of the α-ketoglutarate-glutamate-glutamine pathway toward purine metabolism, ultimately leading to a decline in adenine nucleotide interconversion. Exogenous adenosine monophosphate (AMP) and adenosine triphosphate (ATP) enhance the killing efficacy of Meropenem against CRAB. The combination of ATP and Meropenem also has a synergistic effect on eliminating CRAB persisters and the biofilm, as well as protecting mice against peritonitis-sepsis. This study presents a novel therapeutic modality to treat infections caused by CRAB based on the metabolism reprogramming strategy.

Activated mesenchymal stem cells increase drug susceptibility of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa.

Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa are major causes of hospital-acquired infections and sepsis. Due to increasing antibiotic resistance, new treatments are needed. Mesenchymal stem cells (MSCs) have antimicrobial effects, which can be enhanced by preconditioning with antibiotics. This study investigated using antibiotics to strengthen MSCs against MRSA and P. aeruginosa. MSCs were preconditioned with linezolid, vancomycin, meropenem, or cephalosporin. Optimal antibiotic concentrations were determined by assessing MSC survival. Antimicrobial effects were measured by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antimicrobial peptide (AMP) gene expression. Optimal antibiotic concentrations for preconditioning MSCs without reducing viability were 1 µg/mL for linezolid, meropenem, and cephalosporin and 2 µg/mL for vancomycin. In MIC assays, MSCs preconditioned with linezolid, vancomycin, meropenem, or cephalosporin inhibited MRSA or P. aeruginosa growth at lower concentrations than non-preconditioned MSCs (p ≤ 0.001). In MBC assays, preconditioned MSCs showed enhanced bacterial clearance compared to non-preconditioned MSCs, especially when linezolid and vancomycin were used against MRSA (p ≤ 0.05). Preconditioned MSCs showed increased expression of genes encoding the antimicrobial peptide genes hepcidin and LL-37 compared to non-preconditioned MSCs. The highest hepcidin expression was seen with linezolid and vancomycin preconditioning (p ≤ 0.001). The highest LL-37 expression was with linezolid preconditioning (p ≤ 0.001). MSCs' preconditioning with linezolid, vancomycin, meropenem, or cephalosporin at optimal concentrations enhances their antimicrobial effects against MRSA and P. aeruginosa without compromising viability. This suggests preconditioned MSCs could be an effective adjuvant treatment for antibiotic-resistant infections. The mechanism may involve upregulation of AMP genes.

Campylobacter fetus-induced primary psoas abscess in patient with gouty arthritis: A case report and literature review.

RATIONALE: Campylobacter fetus is rare pathogen with high mortality rate in immunosuppressive hosts. This study aimed to summarize clinical and pathological presentation of C fetus induced psoas abscess. PATIENT CONCERNS: A 66-year-old male patient with long medical history of poorly-controlled gouty arthritis and steroid intake complained of a severe low back pain. Physical examination showed tenderness in his psoas. DIAGNOSES: The patient underwent puncture biopsy to the lesion in the psoas under ultrasound guidance. The lesion was indicated as abscess by pathological examination, and its pathogen was indicated as C fetus by the next generation sequencing. INTERVENTIONS: Meropenem 1 g q8.h were administered intravenously for 10 days. Then the antibiotic treatment was switched to amoxicillin/clavulanate potassium 0.375g q.8.h and levofloxacin 0.5g q.d oral administration when discharge. OUTCOMES: The patient's fever and low back pain improved and infectious parameters declined. He was discharged in good general condition with advice for further monitoring and therapy. In the first month follow-up, the patient did not report recurrence or aggravation of his symptoms. LESSONS: C fetus should be noticed in immunosuppressive patient with exposure to livestock who present with rare systematic or local invasive infection. We advocated the meropenem for the first-line treatment against C fetus.

Carbapenem-resistant Klebsiella pneumoniae Osteoarthritis in Two Preterm Infants Treated With Ceftazidime-avibactam.

BACKGROUND: The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a major threat to global public health. CRKP infections are challenging to treat owing to the limited number of antibiotic species, especially in preterm infants. Ceftazidime-avibactam (CAZ-AVI) is a novel antibiotic with activity against CRKP. At present, there have been no reports of using CAZ-AVI to treat osteoarthritis in premature infants. METHODS: We describe 2 preterm infants with CRKP osteoarthritis treated with CAZ-AVI in a tertiary children's hospital in China. Clinical characteristics, laboratory and microbiologic data, treatment and follow-up information were retrospectively collected and analyzed. RESULTS: The 2 cases were both premature infants who contracted sepsis and CRKP osteoarthritis. Meropenem and polymyxin B were initially chosen for the first infant. CAZ-AVI was then used due to persistent infection. The second infant was commenced immediately on CAZ-AVI after receipt of antimicrobial susceptibility on the 4th day after admission. Both recovered with CAZ-AVI (50 mg/kg q8h) and surgical incision and drainage. Neither had a joint deformity or limb length discrepancy at 36 and 34 months, respectively. CONCLUSIONS: This is the first report on the use of CAZ-AVI to treat CRKP osteoarthritis in premature infants. Successful treatment depends on prompt recognition of the pathogen and treatment with a combination of antibiotics with or without surgery. Further study is needed to determine the pharmacokinetics and pharmacodynamics of CAZ-AVI for treating preterm infants with serious CRKP osteoarthritis.

Periprosthetic joint infection:A South African perspective.

BACKGROUND: South African data on the bacteriology and sensitivity profile of periprosthetic joint infection is lacking.  Current regimens for systemic and local antibiotic therapy are based on international literature. These regimens are different for the United States of America and Europe and might thus not be relevant to South Africa. OBJECTIVES: To determine the characteristics of periprosthetic joint infection in a South African clinical setting by identifying the most common organisms cultured and establishing their antibiotic sensitivities in order to propose the most appropriate empiric antibiotic treatment regimen. In the case of two-stage revision procedures, we aim to compare the organisms cultured during the first stage versus organisms cultured during the second stage in second-stage procedures that had positive cultures.  Furthermore, in these culture-positive second-stage procedures we aim to correlate the bacterial culture with the erythrocyte sedimentation rate/ C-reactive protein result. METHODS: We performed a retrospective cross-sectional study looking at all hip and knee periprosthetic joint infections in patients 18 years and older, treated at a government institution and a private revision practice in Johannesburg, South Africa between January 2015 and March 2020. Data were collected from the Charlotte Maxeke Johannesburg Academic Hospital hip and knee and the Johannesburg Orthopaedic hip and knee databanks. RESULTS: We included 69 patients whom underwent 101procedures relating to periprosthetic joint infection. Positive cultures were found in 63 samples, 81 different organisms were identified. The most common organisms cultured were Staphylococcus aureus (n = 16, 19.8%) and Coagulase negative Staphylococcus (n = 16, 19.8%), followed by Streptococci species (n = 11, 13.6%).  The positive yield in our cohort was 62.4% (n = 63). A polymicrobial growth was found in 19% (n = 12) of the culture positive specimens. Of all the microorganisms cultured, 59.2% (n = 48) were Gram-positive versus 35.8% (n = 29) Gram-negative. The remainder were fungal and anaerobic organisms at 2.5% (n = 2) each. Gram-positive cultures displayed 100% sensitivity to Vancomycin and Linezolid, whereas Gram-negative organisms displayed 82% sensitivity towards Gentamycin and 89% sensitivity towards Meropenem respectively. CONCLUSION: Our study identifies the bacteriology of periprosthetic joint infections and their sensitivities in a South African setting. We recommend that empiric antibiotic-loaded cement spacers and systemic antibiotic regimens should consist of Meropenem or Gentamycin; Vancomycin and Rifampicin to achieve the broadest spectrum of coverage and most likely success in eradicating infection.

A case of Robinsoniella peoriensis bacteremia during using piperacillin-tazobactam.

Infections caused by Robinsoniella peoriensis, particularly bacteremia, are rare, of which only six cases were reported R. peoriensis bloodstream infections. This case report describes an instance of R. peoriensis bacteremia arising while we treated the patient with piperacillin-tazobactam. We treated an 84-year-old female patient with peritoneal carcinoma and febrile neutropenia using piperacillin-tazobactam. The patient's fever subsided. However, she developed a fever again on the fourth day of treatment with piperacillin-tazobactam. Blood cultures taken at this time were positive for R. peoriensis. We substituted meropenem and vancomycin for piperacillin-tazobactam, after which the patient improved. We administered meropenem and vancomycin for 17 days. There is currently no appropriate established treatment for R. peoriensis. In this case, we isolated R. peoriensis from blood cultures using piperacillin-tazobactam, although it was susceptible to piperacillin-tazobactam in vitro. Therefore, monotherapy with penicillins, especially piperacillin-tazobactam, may not be sufficient for R. peoriensis infections, although it was susceptible in vitro. Carbapenem may be effective in the treatment of R. peoriensis bloodstream infections.

Development of Meropenem Resistance in a Multidrug-Resistant Campylobacter coli Strain Causing Recurrent Bacteremia in a Hematological Malignancy Patient.

Campylobacter bacteremia is an uncommon disease that mainly occurs in immunocompromised patients and is associated with antibiotic resistance, particularly in Campylobacter coli. We report a patient with persistent blood infection because of a multidrug-resistant (MDR) C. coli strain over a 3-month period. Through this period monotherapy with meropenem was associated with the development of resistance to it. Improving immunity status and a combined therapy for intestinal decolonization were useful to control persistent C. coli infection in this patient.

Complex Lemierre syndrome with multisystemic abscesses.

We present here the challenging case of severe Lemierre syndrome in a healthy woman in her late twenties, whose clinical presentation was characterised by lung abscesses and disseminated systemic abscesses in the brain, the abdomen and the soft-tissues, as a likely consequence of a patent foramen ovale. Blood cultures were positive for Fusobacterium necrophorum and a right lingual vein thrombosis was detected at a late stage when the patient developed a septic shock. Initial antimicrobial therapy with metronidazole and ceftriaxone was modified to meropenem due to progressive worsening. The patient underwent laparoscopy and neurosurgical drainage of a cerebral abscess. She spent many days in the intensive care unit and recovered fully after 6 weeks on meropenem therapy. Although considered rare, the incidence of Lemierre syndrome, a potentially life-threatening condition, is increasing. The clinician should promptly recognise and treat it while being aware of its potential atypical presentations.

Spontaneous nosocomial Proteus mirabilis meningitis in a Human Immunodeficiency Virus (HIV)-infected adult patient: a case report.

BACKGROUND: Gram-negative bacillary meningitis remains a rare occurrence, even in patients with human immunodeficiency virus. Current literature only describes anecdotal cases of spontaneous nosocomial Proteus mirabilis meningitis. This report describes the clinical manifestations and management of a patient with healthcare-associated spontaneous Gram-negative bacillary meningitis in a patient with advanced human immunodeficiency virus disease. CASE PRESENTATION: A 23-year-old Congolese female was hospitalized in a human immunodeficiency virus specialized center for ongoing weight loss, chronic abdominal pain, and vomiting 9 months after initiation of treatment for tuberculosis meningitis. Hospitalization was complicated by healthcare-associated Gram-negative bacillary meningitis on day 18. Blood and cerebrospinal fluid cultures confirmed Proteus mirabilis. Antibiotic susceptibility testing showed extended spectrum beta-lactamase resistant to common antibiotics, and sensitive to meropenem. Despite initiation of high-dose meropenem by intravenous infusion (2 g every 8 hours), the patient did not improve, and died after 4 days of meropenem treatment. Gram-negative bacillary meningitis remains rare and is associated with an unfavorable prognosis. CONCLUSIONS: This case report highlights the importance of microbiological identification of pathogens in resource-limited settings. As Gram-negative bacillary meningitis does not present with pleocytosis in patients with advanced human immunodeficiency virus, a negative lumbar puncture cannot exclude this diagnosis. Access to clinical bacteriology in resource-limited settings is essential to enable correct antibiotic treatment and avoid overuse of antibiotics to which there is already resistance. It further plays an essential role in public health by identifying antibiotic susceptibilities. Infection prevention and control measures must be reinforced in order to protect patients from such avoidable healthcare-associated infections.

Combination of GM CSF and carbapenem is superior to carbapenem monotherapy in difficult-to-treat spontaneous bacterial peritonitis: A randomized controlled trial.

BACKGROUND: Patients with cirrhosis and treatment non-responsive spontaneous bacterial peritonitis (SBP) have high mortality. We aimed to investigate whether GM-CSF can improve SBP response rates. PATIENTS AND METHODS: In this open-label RCT, 131 cirrhosis patients with difficult-to-treat SBP (DTT SBP) were randomized to receive meropenem alone (1 g IV thrice daily for 5 days) (MERO Group, n = 66) or in combination with GM-CSF (1.5 mcg/Kg daily IV till resolution or till 5d) (MEROGM Group, n = 65). The primary end-point was SBP early-response (reduction in absolute neutrophil count (ANC) by >25% after 48 h). Secondary end-points included SBP resolution at day 5. RESULTS: Patients in MEROGM group in comparison to MERO group had higher SBP early-response (60% vs. 31.8%; p = .001) and SBP resolution rates (55.4% vs. 24.2%; p = .0003). Patients in the combination arm also had better resolution of pneumonia {8/17 (47.05%) vs. 2/19 (10.5%), p = .02} and lower incidence of new-onset AKI (15.4% vs. 31.8%, p = .02), HE (18.5% vs. 34.8%, p = .04) and infections (21.5% vs. 37.9%, p = .05). In comparison to MERO group, 7-day survival was higher in MEROGM group (89.2% vs. 78.7%, p = .03), though the 28-day survival was comparable (78.4% vs. 71.2%; p = .66). None of the patients developed treatment-related severe adverse effects requiring discontinuation of therapy. CONCLUSIONS: The addition of GM-CSF to meropenem significantly improves response rates in DTT SBP patients within 48 h. Early use of GMCSF modulates host immune response, and enhances antibiotic response with higher SBP resolution. The use of GMCSF needs to be considered in combating difficult SBP in cirrhosis patients.

Brain Abscesses Caused by Nocardia farcinica in a 44-Year Old Woman with Multiple Myeloma: A Rare Case and Review of the Literature.

BACKGROUND Central nervous system infection by the Nocardia species is associated with high morbidity and mortality. Its occurrence in patients with multiple myeloma is rare and acquisition of the infection in such patients was associated with the use of novel therapeutic agents (eg, bortezomib and lenalidomide) or bone marrow transplantation. Here, we report the first case of Nocardia brain abscesses in a patient with multiple myeloma, without the above risk factors. CASE REPORT A 44-year-old woman with IgG-kappa type multiple myeloma presented with generalized tonic-clonic seizures. Magnetic resonance imaging of the brain revealed 3 space-occupying lesions in left frontal, left parietal, and right parietal regions. Craniotomy and enucleation of the left frontal lesion revealed an abscess. The culture result was Nocardia farcinica. The patient was treated with meropenem, amikacin, and trimethoprim-sulfamethoxazole for 6 weeks, followed by trimethoprim-sulfamethoxazole for 12 months, with good outcome. CONCLUSIONS Cerebral nocardiosis is a rare entity and its occurrence in our case may hint toward myeloma-associated humoral immune dysfunction as a pathogenesis and the importance of humoral immunity in the defense against this infection. However, chemotherapy-induced cell-mediated dysfunction cannot be ruled out as a risk factor for the infection. Despite its rarity, this case aims to raise awareness of the condition and reiterate the importance of considering the rare but life-threatening conditions in the differential diagnosis of brain lesions, especially when there is a misdiagnosis of the radiological findings, as occurred in this and previous cases; this avoids delays in appropriate surgical and medical treatment, which can affect outcomes.

Carbapenem-resistant Enterobacteriaceae bloodstream infections: A case-control study from a pediatric referral hospital in Argentina.

Background: Antibiotic-resistant gram-negative bloodstream infections (BSI) remain a leading cause morbidity and mortality in pediatric patients with a high impact on the public health system. Data in resource-limited countries, including those in Latin America and the Caribbean region, are scarce. The aim of the study was to identify risk factors for acquiring carbapenem-resistant Enterobacteriaceae (CRE) bacteremia in children and to assess the use of resources. Methods: A retrospective case-control study was conducted to analyze demographic, epidemiological, clinical, microbiological, and outcome data as well as the use of resources between 2014 and 2019. Univariate and logistic regression analysis was performed in order to identify risk factors associated with CRE-BSI. The R software version 4.1.2 was used. Results: A total of 46 cases with CRE-BSI and 92 controls with gram-negative non-CRE-BSI were included. No statistical difference was observed regarding: median age (36 months; IQR, 11.2-117 vs. 48 months, IQR 13-119), male sex (50 vs. 60%), and underlying disease (98 vs. 91%) in cases vs. controls, respectively. The most frequent mechanism of CRE bacteremia were: KPC in 74%, OXA in 15%, and NDM in 6.5%. A total of 54.3% of cases vs. 32.6 % (p = 0.016) of controls were admitted to the pediatric intensive care unit (PICU), and 48 vs. 21% (p = 0.001) required mechanical ventilation. Bacteremia secondary to intra-abdominal infection was observed in 56.5% of cases vs. 35% of controls (p = 0.032). Previous colonization with CRE was detected in 76% of cases vs. 8% of controls. Combination antimicrobial treatment was most frequent in cases vs. control (100 vs. 56.5%). No difference was observed in median length of hospital stay (22 days; IQR, 19-31 in cases vs. 17.5 days; IQR, 10-31 in controls; p = 0.8). Overall case fatality ratio was 13 vs. 5.5%, respectively. The most statistically significant risk factors included previous PICU stay (OR, 4; 95%CI, 2-8), invasive procedures/surgery (OR, 3; 95%CI, 1-7), central venous catheter placement (OR, 6.5; 95%CI, 2-19), urinary catheter placement (OR, 9; 95%CI 4-20), mechanical ventilation (OR, 4; 95%CI, 2-10), liver transplantation (OR, 8; 95%CI, 2-26), meropenem treatment (OR, 8.4; 3.5-22.6) in univariate analysis. The logistic regression model used for multivariate analysis yielded significant differences for previous meropenem treatment (OR, 13; 95%CI, 3-77; p = 0.001), liver transplantation (OR, 13; 95%CI, 2.5-100; p = 0.006), and urinary catheter placement (OR, 9; 95%CI, 1.4-94; p = 0.03). Conclusion: CRE-BSI affects hospitalized children with underlying disease, mainly after liver transplantation, with previous urinary catheter use and receiving broad-spectrum antibiotics, leading to high PICU requirement and mortality. These risk factors will have to be taken into account in our region in order to establish adequate health policies and programs to improve antimicrobial stewardship.

Long-Term Dominance of Carbapenem-Non-Susceptible Pseudomonas aeruginosa ST111 in Hematologic Malignancy Patients and Hematopoietic Cell Transplant Recipients.

An epidemiological study uncovered that fluoroquinolone (FQ) neutropenic prophylaxis in hematopoietic cell transplant and hematologic malignancy (HCT/HM) patients was associated with breakthrough Pseudomonas aeruginosa bloodstream infections (BSIs) with isolates non-susceptible to both FQs and meropenem. The molecular epidemiology of the FQ/meropenem-non-susceptible P. aeruginosa isolates causing FQ-breakthrough BSIs in the HCT/HM patients remains unclear. Through whole genome sequencing on 57 P. aeruginosa isolates from 54 patients diagnosed with HM or receiving an HCT, we found that ST111 strains predominated, accounting for 22 (38.6%) of the isolates. 17 of 33 (51.5%) FQ-breakthrough BSIs were caused by ST111 strains, of which 15 (88.2%) were meropenem non-susceptible. ST111 strains, but not other oprD-deficient, meropenem-non-susceptible clinical strains, were found to have a colonization advantage over P. aeruginosa strain PA14 in C. elegans and to outcompete PA14 in in vitro co-culture assays. Together, we found that breakthrough P. aeruginosa BSIs during FQ prophylaxis in HCT/HM patients are dominated by clonally-related FQ/meropenem non-susceptible strains, predominantly ST111 type, and that the dominance of ST111 strains may be explained by a relative fitness advantage over other clinical strains. Additional work is necessary to better understand the factors driving the dominance and persistence of these ST111 strains.

Antibiotic allergy in children with cystic fibrosis: A retrospective case-control study.

Antibiotic allergy is a big problem that may affect the treatment and life quality of patients with cystic fibrosis (CF). AIM: To evaluate predictive factors for confirmed antibiotic hypersensitivity in children with CF. METHODS: In this case-controlled study, we examined 15 patients with CF who had been confirmed with antibiotic allergy. Additionally, we included a control group of age- and gender-matched 45 CF patients with no antibiotic allergy. The diagnosis of antibiotic allergy was confirmed in the presence of a compatible history and a positive response in the drug skin test or provocation test. Multiple drug hypersensitivity was classified according to the temporal relationship of antibiotics: (i) distant, (ii) simultaneous, and (iii) sequential. The data were analyzed by conditional logistic regression. RESULTS: ß-lactam allergy was confirmed in eight patients (ceftazidime n = 5, piperacillin-tazobactam n = 3) and non-ß-lactam allergy was confirmed in two patients (ciprofloxacin n = 1, azithromycin n = 1). Additionally, multiple drug hypersensitivity in five patients (distant n = 4, sequential n = 1), among whom two patients showed hypersensitivity against ceftazidime/piperacillin-tazobactam+ ciprofloxacin/levofloxacin, two patients showed hypersensitivity against ceftazidime+ ciprofloxacin n = 2, and one patient showed hypersensitivity against piperacillin-tazobactam+ amikacin+ trimethoprim-sulfamethoxazole. All patients (n = 13) with confirmed ß-lactam allergy were meropenem tolerant. Multivariate analysis indicated that immediate reactions (, p < 0.001) and allergic evaluation in the first six months after the reaction (p = 0.036) were significant risk factors for the prediction of antibiotic hypersensitivity. CONCLUSION: Beta-lactam antibiotic allergy is the most commonly confirmed drug allergy in children with CF. However, unlike normal children, ceftazidime and piperacillin-tazobactam account for the majority.