Fei Lam Wong
@feilamwong.bsky.social
#OTILT Beyond resistance mechanisms like β-lactamases and porin loss, Acinetobacter baumannii uses BfmRS, where the sensor kinase BfmS activates the response regulator BfmR, to upregulate efflux pumps, biofilm formation, and envelope protection to enhance persistence and multidrug resistance.
Acinetobacter baumannii Regulates Its Stress Responses via the BfmRS Two-Component Regulatory System | Journal of Bacteriology
Acinetobacter baumannii is a nosocomial pathogen that has extremely high rates of multidrug resistance. This
organism’s ability to endure stressful conditions is a key part of its ability to
spread in...
journals.asm.org
October 16, 2025 at 8:07 PM
#OTILT Beyond resistance mechanisms like β-lactamases and porin loss, Acinetobacter baumannii uses BfmRS, where the sensor kinase BfmS activates the response regulator BfmR, to upregulate efflux pumps, biofilm formation, and envelope protection to enhance persistence and multidrug resistance.
#OTILT Posaconazole has been associated with pseudohyperaldosteronism, especially at serum concentrations >4 mg/mL. The proposed mechanism is through inhibition of CYP11B1 and CYP11B2, leading to cortisol precursor accumulation that can cause hypertension, hypokalemia, and alkalosis.
Posaconazole Serum Drug Levels Associated With Pseudohyperaldosteronism
Posaconazole tablets are well tolerated and efficacious in the prophylaxis and treatment of aspergillosis, mucormycosis, and other invasive fungal infections. There have been case reports of posaconaz...
pmc.ncbi.nlm.nih.gov
October 15, 2025 at 3:07 PM
#OTILT Posaconazole has been associated with pseudohyperaldosteronism, especially at serum concentrations >4 mg/mL. The proposed mechanism is through inhibition of CYP11B1 and CYP11B2, leading to cortisol precursor accumulation that can cause hypertension, hypokalemia, and alkalosis.
#OTILT Staph lugdunensis (CoNS) detected in 1/2 blood cultures is potentially a contaminant, but this species is often more virulent and so should be treated like Staph aureus. It exhibits ~95% susceptibility to oxacillin, but it can also possess the mecA gene, making vancomycin an appropriate drug.
A Frequently Overlooked Contaminant: A Case of Staphylococcus lugdunensis Bacteremia
pmc.ncbi.nlm.nih.gov
October 10, 2025 at 4:05 PM
#OTILT Staph lugdunensis (CoNS) detected in 1/2 blood cultures is potentially a contaminant, but this species is often more virulent and so should be treated like Staph aureus. It exhibits ~95% susceptibility to oxacillin, but it can also possess the mecA gene, making vancomycin an appropriate drug.
#OTILT The HIV mutation, M184V, confers resistance to emtricitabine and lamivudine, but these agents are often continued despite the mutation because it can reduce viral fitness and increase susceptibility to tenofovir.
The impact of the M184V resistance mutation on treatment outcomes in patients with HIV infection: a systematic review and meta-analysis - PubMed
HIV is a global deliberating infectious disease. Of note, more than 36 million people living with HIV (PLHIV) with approximately newly diagnosed 1.5 million cases annually. M184V is a single base muta...
pubmed.ncbi.nlm.nih.gov
October 9, 2025 at 6:55 PM
#OTILT The HIV mutation, M184V, confers resistance to emtricitabine and lamivudine, but these agents are often continued despite the mutation because it can reduce viral fitness and increase susceptibility to tenofovir.
#OTILT In patients with myelodysplastic syndrome and acute myeloid leukemia receiving chemotherapy, acyclovir is often prescribed for HSV and VZV prophylaxis due to the decreased immunocompetence from the disease, which can increase the risk of infection or reactivation.
Acyclovir prophylaxis against herpes simplex virus infection in patients with leukemia. A randomized, double-blind, placebo-controlled study - PubMed
Twenty-nine adult patients with acute leukemia receiving timed sequential chemotherapy participated in a randomized, double-blind, placebo-controlled trial of acyclovir prophylaxis against reactivated...
pubmed.ncbi.nlm.nih.gov
October 8, 2025 at 4:55 PM
#OTILT In patients with myelodysplastic syndrome and acute myeloid leukemia receiving chemotherapy, acyclovir is often prescribed for HSV and VZV prophylaxis due to the decreased immunocompetence from the disease, which can increase the risk of infection or reactivation.
#OTILT Pseudomonas resistance to meropenem is typically driven by overexpression of efflux pumps like MexAB-OprM, while resistance to imipenem is more commonly mediated by OprD porin channel loss. Therefore, Pseudomonas resistance to imipenem cannot be generalized to meropenem.
Carbapenem Resistance Mechanisms in Pseudomonas aeruginosa Clinical Isolates
In order to define the contributions of the mechanisms for carbapenem resistance in clinical strains of Pseudomonas aeruginosa, we investigated the presence of OprD, the expressions of the MexAB-OprM ...
pmc.ncbi.nlm.nih.gov
October 7, 2025 at 4:16 PM
#OTILT Pseudomonas resistance to meropenem is typically driven by overexpression of efflux pumps like MexAB-OprM, while resistance to imipenem is more commonly mediated by OprD porin channel loss. Therefore, Pseudomonas resistance to imipenem cannot be generalized to meropenem.
#OTILT An oncology patient who has febrile neutropenia will require a broad antibiotic such as cefepime until count recovery to an ANC of at least 500. If the patient is still febrile after count recovery, an antibiotic is no longer required but possible infection should be investigated.
Febrile Neutropenia
Neutropenic fever is when there is a single oral temperature greater than or equal to 101 F (38.3 C) or a temperature greater than or equal to 100.4 F (38 C) for at least an hour, with an absolute neu...
www.ncbi.nlm.nih.gov
October 6, 2025 at 8:01 PM
#OTILT An oncology patient who has febrile neutropenia will require a broad antibiotic such as cefepime until count recovery to an ANC of at least 500. If the patient is still febrile after count recovery, an antibiotic is no longer required but possible infection should be investigated.
#OTILT Burkholderia cepacia complex (BCC) is a Gram-negative, non-fermenting rod that can contaminate medical and pharmaceutical products like ultrasound gel and chlorhexidine. This can cause BCC outbreaks, especially in those who are immunocompromised or ventilated.
Burkholderia cepacia Complex Bacteria: a Feared Contamination Risk in Water-Based Pharmaceutical Products
Burkholderia cepacia (formerly Pseudomonas cepacia) was once thought to be a single bacterial species but has expanded to the Burkholderia cepacia complex (Bcc), comprising 24 closely related opportun...
pmc.ncbi.nlm.nih.gov
October 3, 2025 at 5:00 PM
#OTILT Burkholderia cepacia complex (BCC) is a Gram-negative, non-fermenting rod that can contaminate medical and pharmaceutical products like ultrasound gel and chlorhexidine. This can cause BCC outbreaks, especially in those who are immunocompromised or ventilated.
#OTILT Resistance to one echinocandin confers resistance to the whole class because it is a target site mutation, and they all share the same target. However, resistance to one azole does not always confer resistance to other azoles because there are multiple different resistance mechanisms.
Resistance of Candida to azoles and echinocandins worldwide - PubMed
Increased resistance to azoles and echinocandins by Candida species is an increasingly serious problem in clinical settings worldwide. Understanding the mechanisms used against antifungal drugs is imp...
pubmed.ncbi.nlm.nih.gov
October 2, 2025 at 5:08 PM
#OTILT Resistance to one echinocandin confers resistance to the whole class because it is a target site mutation, and they all share the same target. However, resistance to one azole does not always confer resistance to other azoles because there are multiple different resistance mechanisms.
#OTILT Not all patients taking linezolid will experience thrombocytopenia from bone marrow suppression, but it typically takes about two weeks to observe a drop in platelet count in those who experience it since platelets have a lifespan of about 7-10 days.
Risk factors associated with the development of thrombocytopenia in patients who received linezolid therapy - PubMed
The major adverse event associated with linezolid treatment is thrombocytopenia. This study investigated risk factors associated with the development of thrombocytopenia in patients who received linez...
pubmed.ncbi.nlm.nih.gov
October 1, 2025 at 4:10 PM
#OTILT Not all patients taking linezolid will experience thrombocytopenia from bone marrow suppression, but it typically takes about two weeks to observe a drop in platelet count in those who experience it since platelets have a lifespan of about 7-10 days.
#OTILT PJP prophylaxis is not only indicated for patients with HIV or transplant. Patients on long-term high-dose steroids (equivalent to at least 20 mg/d of prednisone for at least 4 weeks) should also be started on PJP prophylaxis due to immunosuppression.
Prophylaxis Against Pneumocystis Pneumonia
To the Editor A recent JAMA Insights article reviewed indications for Pneumocystis jirovecii pneumonia prophylaxis in immunocompromised adults.1 The authors commented that patients receiving corticost...
jamanetwork.com
September 30, 2025 at 6:15 PM
#OTILT PJP prophylaxis is not only indicated for patients with HIV or transplant. Patients on long-term high-dose steroids (equivalent to at least 20 mg/d of prednisone for at least 4 weeks) should also be started on PJP prophylaxis due to immunosuppression.
#OTILT Amoebocytes found in the blood of horseshoe crabs clot in response to the 1,3-beta-D-glucan found in fungi. The degree of coagulation is considered proportional to the amount of 1,3-beta-D-glucan present in the sample, allowing it to provide a quantitative result.
Plasma (1-->3)-beta-D-glucan assay and immunohistochemical staining of (1-->3)-beta-D-glucan in the fungal cell walls using a novel horseshoe crab protein (T-GBP) that specifically binds to (1-->3)-be...
A highly sensitive enzyme-linked immunosorbent assay specific to (1-->3)-beta-D-glucans (GBP-ELISA) has been developed using a novel (1-->3)-beta-D-glucan-binding protein (T-GBP), which was purified f...
pubmed.ncbi.nlm.nih.gov
September 29, 2025 at 5:52 PM
#OTILT Amoebocytes found in the blood of horseshoe crabs clot in response to the 1,3-beta-D-glucan found in fungi. The degree of coagulation is considered proportional to the amount of 1,3-beta-D-glucan present in the sample, allowing it to provide a quantitative result.
#OTILT Similar to urine and urine cultures, respiratory cultures that contain squamous epithelial cells are typically associated with oral flora contamination and may not represent any true organisms present in the lower respiratory tract.
Sputum analysis and culture - PubMed
Sputum analysis and culture is the most common method of specific diagnosis of lower respiratory tract infections. Culture of a properly screened, expectorated sputum sample will identify the pathogen...
pubmed.ncbi.nlm.nih.gov
September 26, 2025 at 4:57 PM
#OTILT Similar to urine and urine cultures, respiratory cultures that contain squamous epithelial cells are typically associated with oral flora contamination and may not represent any true organisms present in the lower respiratory tract.
#OTILT Pseudomonas aeruginosa can be meropenem-resistant but cephalosporin-susceptible because of mutated porin channels that block out meropenem but not cephalosporins. This mechanism could have been developed from prior exposure to carbapenems (selective pressure).
Carbapenem-resistant and cephalosporin-susceptible: a worrisome phenotype among Pseudomonas aeruginosa clinical isolates in Brazil
The mechanisms involved in the uncommon resistance phenotype, carbapenem resistance and broad-spectrum cephalosporin susceptibility, were investigated…
www.sciencedirect.com
September 25, 2025 at 5:45 PM
#OTILT Pseudomonas aeruginosa can be meropenem-resistant but cephalosporin-susceptible because of mutated porin channels that block out meropenem but not cephalosporins. This mechanism could have been developed from prior exposure to carbapenems (selective pressure).
#OTILT In patients with indication for long-term urinary catheters, suprapubic catheters are generally preferred over indwelling catheters due to the lower risk of catheter-associated urinary tract infections since they bypass the urethra, which is a common entry point for bacteria.
Indwelling urethral versus suprapubic catheters in nursing home residents: determining the safest option for long-term use - PubMed
Residents with a suprapubic catheter may have fewer CAUTIs, less hospitalization and less antibiotic use, but are more likely colonized with MDROs.
pubmed.ncbi.nlm.nih.gov
September 24, 2025 at 4:55 PM
#OTILT In patients with indication for long-term urinary catheters, suprapubic catheters are generally preferred over indwelling catheters due to the lower risk of catheter-associated urinary tract infections since they bypass the urethra, which is a common entry point for bacteria.
#OTILT Negative MRSA nasal swabs are mainly limited to the respiratory tract. It can help rule out MRSA in respiratory infections, but it cannot necessarily indicate absence of MRSA in other infections in other parts of the body.
MRSA colonisation (eradicating colonisation in people without active invasive infection)
Methicillin-resistant Staphylococcus aureus (MRSA) contains a gene that makes it resistant to methicillin as well as to other beta-lactam antibiotics, including flucloxacillin, cephalosporins, and car...
pmc.ncbi.nlm.nih.gov
September 23, 2025 at 3:42 PM
#OTILT Negative MRSA nasal swabs are mainly limited to the respiratory tract. It can help rule out MRSA in respiratory infections, but it cannot necessarily indicate absence of MRSA in other infections in other parts of the body.
#OTILT Ascariasis is a roundworm infection and the most common human parasitic infection. An adult Ascaris worm can live about 1-2 years in the small intestine and lay up to 250,000 eggs per day, which can be observed in the patient’s stool to confirm Ascaris infection.
Ascariasis
Approximately one billion people worldwide are infected with Ascaris lumbricoides, and more than 60,000 people die from the disease annually. It affects mostly tropical and subtropical countries aroun...
www.ncbi.nlm.nih.gov
September 22, 2025 at 7:27 PM
#OTILT Ascariasis is a roundworm infection and the most common human parasitic infection. An adult Ascaris worm can live about 1-2 years in the small intestine and lay up to 250,000 eggs per day, which can be observed in the patient’s stool to confirm Ascaris infection.
#OTILT Sputum samples help diagnose respiratory infections, and they can be expectorated or induced. Expectorated sputum is naturally coughed up while induced sputum is obtained by having the patient inhale hypertonic saline and cough, so induced sputum is from deeper within the respiratory tract.
Comparison of induced versus expectorated sputum for diagnosis of pulmonary tuberculosis by acid-fast smear - PubMed
We found sputum induction to be costly, and induced sputum offered no advantage over routine expectorated sputum for the diagnosis of pulmonary tuberculosis.
pubmed.ncbi.nlm.nih.gov
September 19, 2025 at 7:45 PM
#OTILT Sputum samples help diagnose respiratory infections, and they can be expectorated or induced. Expectorated sputum is naturally coughed up while induced sputum is obtained by having the patient inhale hypertonic saline and cough, so induced sputum is from deeper within the respiratory tract.
#OTILT Voriconazole exhibits variable plasma concentrations between patients due to CYP2C19 polymorphisms and nonlinear PK. Therefore, patients with abnormal drug levels on a normal dose should be tested for CYP2C19 polymorphism, and dose adjustments should be made slowly and cautiously.
CYP2C19 Polymorphisms and Therapeutic Drug Monitoring of Voriconazole: Are We Ready for Clinical Implementation of Pharmacogenomics?
Since its approval by the United States Food and Drug Administration in 2002, voriconazole has become a key component in the successful treatment of many invasive fungal infections, including the most...
pmc.ncbi.nlm.nih.gov
September 18, 2025 at 6:05 PM
#OTILT Voriconazole exhibits variable plasma concentrations between patients due to CYP2C19 polymorphisms and nonlinear PK. Therefore, patients with abnormal drug levels on a normal dose should be tested for CYP2C19 polymorphism, and dose adjustments should be made slowly and cautiously.
#OTILT Administration of an azole antifungal before or during administration of a polyene antifungal will reduce the efficacy of the polyene because azoles inhibit the synthesis of ergosterol, while polyenes need to bind to ergosterol to exert their antifungal effect.
The effects of azole and polyene antifungals on the plasma membrane enzymes of Candida albicans
The two clinically important classes of antimycotic drugs, the polyenes and azoles, act on the plasma membrane of the cell. The primary modes of action are believed to be through interaction with s...
www.tandfonline.com
September 17, 2025 at 6:35 PM
#OTILT Administration of an azole antifungal before or during administration of a polyene antifungal will reduce the efficacy of the polyene because azoles inhibit the synthesis of ergosterol, while polyenes need to bind to ergosterol to exert their antifungal effect.
#OTILT Pneumonia caused by non-fermenting Gram- bacteria, such as Acinetobacter and Pseudomonas, has a higher rate of relapse, and the treatment duration should be extended for these infections to prevent recurrence. @bwdionne.bsky.social @bridgetehrig.bsky.social @jeffpears0n.bsky.social
Risk factors for relapse of ventilator-associated pneumonia related to nonfermenting Gram negative bacilli: A case–control study
The aim of this study was to determine risk factors for relapse of ventilator-associated pneumonia (VAP) related to nonfermenting Gram negative bacill…
www.sciencedirect.com
September 16, 2025 at 5:38 PM
#OTILT Pneumonia caused by non-fermenting Gram- bacteria, such as Acinetobacter and Pseudomonas, has a higher rate of relapse, and the treatment duration should be extended for these infections to prevent recurrence. @bwdionne.bsky.social @bridgetehrig.bsky.social @jeffpears0n.bsky.social
#OTILT If an organism is resistant to ceftriaxone but susceptible to ampicillin/sulbactam and piperacillin/tazobactam, it may not be a true ESBL-producer and thus may not warrant the use of a carbapenem. @bwdionne.bsky.social @bridgetehrig.bsky.social @jeffpears0n.bsky.social
journals.asm.org
September 15, 2025 at 6:50 PM
#OTILT If an organism is resistant to ceftriaxone but susceptible to ampicillin/sulbactam and piperacillin/tazobactam, it may not be a true ESBL-producer and thus may not warrant the use of a carbapenem. @bwdionne.bsky.social @bridgetehrig.bsky.social @jeffpears0n.bsky.social
#OTILT Vancomycin levels should be drawn 4-6 hours after hemodialysis to allow for the drug to redistribute from the tissues to the bloodstream after the drug is rapidly cleared during dialysis, which would provide a more accurate trough level compared to drawing immediately after dialysis.
Clinical review: Use of vancomycin in haemodialysis patients - Critical Care
Following intravenous administration, vancomycin is poorly metabolized and is mainly excreted unchanged in urine. Total body clearance is thus dependent on the kidney, and is correlated with glomerula...
ccforum.biomedcentral.com
September 12, 2025 at 6:15 PM
#OTILT Vancomycin levels should be drawn 4-6 hours after hemodialysis to allow for the drug to redistribute from the tissues to the bloodstream after the drug is rapidly cleared during dialysis, which would provide a more accurate trough level compared to drawing immediately after dialysis.
#OTILT Gentamicin is used for Gram+ synergy at 1.7 mg/kg q8h for CNS listeriosis. Gentamicin is a concentration-dependent drug that can be dosed 7 mg/kg daily for less toxicity and higher efficacy, but it is still unclear whether this dosing regimen works for synergy purposes.
Gentamicin combination treatment is associated with lower mortality in patients with invasive listeriosis: a retrospective analysis - PubMed
This retrospective study highlights the benefit of gentamicin combination treatment in reducing the 90-day mortality rate among patients with invasive listeriosis. The high prevalence of monotherapy i...
pubmed.ncbi.nlm.nih.gov
September 11, 2025 at 6:05 PM
#OTILT Gentamicin is used for Gram+ synergy at 1.7 mg/kg q8h for CNS listeriosis. Gentamicin is a concentration-dependent drug that can be dosed 7 mg/kg daily for less toxicity and higher efficacy, but it is still unclear whether this dosing regimen works for synergy purposes.
#OTILT Though QTc prolongation is a class effect of fluoroquinolones, moxifloxacin demonstrated the greatest increase in QTc compared to levofloxacin and ciprofloxacin. QTc prolongation can also be observed within hours of a fluoroquinolone dose when the drug concentration peaks.
Effects of three fluoroquinolones on QT interval in healthy adults after single doses
Objective A clinical trial was conducted in healthy adult volunteers to assess the effect of levofloxacin, moxifloxacin, and ciprofloxacin on the QT and QTc interval. Methods Electrocardiograms we...
doi.org
September 10, 2025 at 7:00 PM
#OTILT Though QTc prolongation is a class effect of fluoroquinolones, moxifloxacin demonstrated the greatest increase in QTc compared to levofloxacin and ciprofloxacin. QTc prolongation can also be observed within hours of a fluoroquinolone dose when the drug concentration peaks.