Contemporary unconventional clinical use of co-trimoxazole

Mechanism of staphylococcal resistance to clinically relevant antibiotics

Staphylococcus aureus, a notorious pathogen with versatile virulence, poses a significant challenge to current antibiotic treatments due to its ability to develop resistance mechanisms against a variety of clinically relevant antibiotics. In this comprehensive review, we carefully dissect the resistance mechanisms employed by S. aureus against various antibiotics commonly used in clinical settings. The article navigates through intricate molecular pathways, elucidating the mechanisms by which S. aureus evades the therapeutic efficacy of antibiotics, such as β-lactams, vancomycin, daptomycin, linezolid, etc. Each antibiotic is scrutinised for its mechanism of action, impact on bacterial physiology, and the corresponding resistance strategies adopted by S. aureus. By synthesising the knowledge surrounding these resistance mechanisms, this review aims to serve as a comprehensive resource that provides a foundation for the development of innovative therapeutic strategies and alternative treatments for S. aureus infections. Understanding the evolving landscape of antibiotic resistance is imperative for devising effective countermeasures in the battle against this formidable pathogen.

Characterization of MultidrugResistant serogroup 19 Streptococcus pneumoniae isolated from healthy children below 5 years of age in Indonesia

We investigated the resistance genes, pilus islets, biofilm formation ability and sequence types of multidrug-resistant Streptococcus pneumoniae (MDRSP) isolated from healthy children below 5 years of age in Indonesia. In all, 104 archived MDRSP isolates from previous carriage studies in Indonesia in 2016-2019 were screened for the presence of antibiotic resistance genes and the rrgC (pilus islet 1) and pitB (pilus islet 2) genes. Multilocus sequence typing and biofilm formation were determined by PCR sequencing and the ability of cells to adhere to the walls, respectively. Results have shown that the mefA, ermB and tetM genes were found in 93, 52 and 100 % of MDRSP isolates, respectively. Insertions of arginine, proline and Ile-100-Leu were the most common mutations in the folA and folP genes. Pilus islets 1 and 2 were discovered in 93 and 82 % of MDRSP isolates, respectively. The MDRSP isolates showed no biofilm formation ability (64 %), and 5 out of 10 strains of MDRSP strains were ST1464. This finding can be used to provide further considerations in implementing and monitoring pneumococcal vaccination in Indonesia.

A guide to Stenotrophomonas maltophilia virulence capabilities, as we currently understand them

The Gram-negative pathogen Stenotrophomonas maltophilia causes a wide range of human infections. It causes particularly serious lung infections in individuals with cystic fibrosis, leading to high mortality rates. This pathogen is resistant to most known antibiotics and harbors a plethora of virulence factors, including lytic enzymes and serine proteases, that cause acute infection in host organisms. S. maltophilia also establishes chronic infections through biofilm formation. The biofilm environment protects the bacteria from external threats and harsh conditions and is therefore vital for the long-term pathogenesis of the microbe. While studies have identified several genes that mediate S. maltophilia's initial colonization and biofilm formation, the cascade of events initiated by these factors is poorly understood. Consequently, understanding these and other virulence factors can yield exciting new targets for novel therapeutics.

Folate-mediated one-carbon metabolism as a potential antifungal target for the sustainable cultivation of microalga Haematococcus pluvialis

BACKGROUND

Microalgae are widely considered as multifunctional cell factories that are able to transform the photo-synthetically fixed CO₂ to numerous high-value compounds, including lipids, carbohydrates, proteins and pigments. However, contamination of the algal mass culture with fungal parasites continues to threaten the production of algal biomass, which dramatically highlights the importance of developing effective measures to control the fungal infection. One viable solution is to identify potential metabolic pathways that are essential for fungal pathogenicity but are not obligate for algal growth, and to use inhibitors targeting such pathways to restrain the infection. However, such targets remain largely unknown, making it challenging to develop effective measures to mitigate the infection in algal mass culture.

RESULTS

In the present study, we conducted RNA-Seq analysis for the fungus Paraphysoderma sedebokerense, which can infect the astaxanthin-producing microalga Haematococcus pluvialis. It was found that many differentially expressed genes (DEGs) related to folate-mediated one-carbon metabolism (FOCM) were enriched in P. sedebokerense, which was assumed to produce metabolites required for the fungal parasitism. To verify this hypothesis, antifolate that hampered FOCM was applied to the culture systems. Results showed that when 20 ppm of the antifolate co-trimoxazole were added, the infection ratio decreased to ~ 10% after 9 days inoculation (for the control, the infection ratio was 100% after 5 days inoculation). Moreover, application of co-trimoxazole to H. pluvialis mono-culture showed no obvious differences in the biomass and pigment accumulation compared with the control, suggesting that this is a potentially algae-safe, fungi-targeted treatment.

CONCLUSIONS

This study demonstrated that applying antifolate to H. pluvialis culturing systems can abolish the infection of the fungus P. sedebokerense and the treatment shows no obvious disturbance to the algal culture, suggesting FOCM is a potential target for antifungal drug design in the microalgal mass culture industry.

Phenotypic and genotypic characterisation of thymine auxotrophy in Escherichia coli isolated from a patient with recurrent bloodstream infection

INTRODUCTION

Thymine auxotrophic in vitro mutants of Escherichia coli were first reported in the mid-20th century. Later, thymine-dependent clinical strains of E. coli as well as other Enterobacterales, Enterococcus faecalis and Staphylococcus aureus have been recognized as the cause of persistent and recurrent infections.

OBJECTIVES

The aim of this study was to characterize the phenotype and investigate the molecular basis of thymine auxotrophy in ten E. coli isolates obtained at different time points from a patient with recurrent bloodstream infection (BSI) due to a chronic aortic graft infection treated with Trimethoprim/sulfamethoxazole (TMP-SMX).

METHODS

Clinical data was obtained from hospital records. Growth characterization and antimicrobial susceptibility testing to TMP-SMX was performed on M9 agar and in MH broth with different thymine concentrations (0.5, 2, 5, 10 and 20 μg/mL), on Mueller-Hinton (MH) and blood agar. Whole genome sequencing (WGS) was performed on all E. coli isolates.

RESULTS

E. coli were isolated from ten consecutive BSI episodes from a patient with chronic aortic graft infection. Six of these isolates were resistant to TMP-SMX when assayed on blood agar. Growth experiments with added thymine confirmed that these isolates were thymine-dependent (thy-), and revealed growth defects (slower growth rate and smaller colony size) in these isolates relative to thy+ isolates (n = 4). WGS indicated that all isolates were of the same clonal lineage of sequence type 7358. Genomic analysis revealed a G172C substitution in thyA in all TMP-SMX resistant isolates, while mutations affecting genes involved in the deoxyribose salvage pathway (deoB and deoC) were identified in eight isolates.

CONCLUSION

This case highlights the risk of resistance development to TMP-SMX, especially for long-term treatment, and the possible pitfalls in detection of growth-deficient subpopulations from chronic infections, which could lead to treatment failure.

Assessing the drug resistance profiles of oral probiotic lozenges

Background

Probiotic lozenges have been developed to harvest the benefits of probiotics for oral health, but their long-term consumption may encourage the transfer of resistance genes from probiotics to commensals, and eventually to disease-causing bacteria.

Aim

To screen commercial probiotic lozenges for resistance to antibiotics, characterize the resistance determinants, and examine their transferability in vitro.

Results

Probiotics of all lozenges were resistant to glycopeptide, sulfonamide, and penicillin antibiotics, while some were resistant to aminoglycosides and cephalosporins. High minimum inhibitory concentrations (MICs) were detected for streptomycin (>128 µg/mL) and chloramphenicol (> 512 µg/mL) for all probiotics but only one was resistant to piperacillin (MIC = 32 µg/mL). PCR analysis detected erythromycin (erm(T), ermB or mefA) and fluoroquinolone (parC or gyr(A)) resistance genes in some lozenges although there were no resistant phenotypes. The dfrD, cat-TC, vatE, aadE, vanX, and aph(3")-III or ant(2")-I genes conferring resistance to trimethoprim, chloramphenicol, quinupristin/dalfopristin, vancomycin, and streptomycin, respectively, were detected in resistant probiotics. The rifampicin resistance gene rpoB was also present. We found no conjugal transfer of streptomycin resistance genes in our co-incubation experiments.

Conclusion

Our study represents the first antibiotic resistance profiling of probiotics from oral lozenges, thus highlighting the health risk especially in the prevailing threat of drug resistance globally.

Nanotechnology as a Novel Approach in Combating Microbes Providing an Alternative to Antibiotics

The emergence of infectious diseases promises to be one of the leading mortality factors in the healthcare sector. Although several drugs are available on the market, newly found microorganisms carrying multidrug resistance (MDR) against which existing drugs cannot function effectively, giving rise to escalated antibiotic dosage therapies and the need to develop novel drugs, which require time, money, and manpower. Thus, the exploitation of antimicrobials has led to the production of MDR bacteria, and their prevalence and growth are a major concern. Novel approaches to prevent antimicrobial drug resistance are in practice. Nanotechnology-based innovation provides physicians and patients the opportunity to overcome the crisis of drug resistance. Nanoparticles have promising potential in the healthcare sector. Recently, nanoparticles have been designed to address pathogenic microorganisms. A multitude of processes that can vary with various traits, including size, morphology, electrical charge, and surface coatings, allow researchers to develop novel composite antimicrobial substances for use in different applications performing antimicrobial activities. The antimicrobial activity of inorganic and carbon-based nanoparticles can be applied to various research, medical, and industrial uses in the future and offer a solution to the crisis of antimicrobial resistance to traditional approaches. Metal-based nanoparticles have also been extensively studied for many biomedical applications. In addition to reduced size and selectivity for bacteria, metal-based nanoparticles have proven effective against pathogens listed as a priority, according to the World Health Organization (WHO). Moreover, antimicrobial studies of nanoparticles were carried out not only in vitro but in vivo as well in order to investigate their efficacy. In addition, nanomaterials provide numerous opportunities for infection prevention, diagnosis, treatment, and biofilm control. This study emphasizes the antimicrobial effects of nanoparticles and contrasts nanoparticles' with antibiotics' role in the fight against pathogenic microorganisms. Future prospects revolve around developing new strategies and products to prevent, control, and treat microbial infections in humans and other animals, including viral infections seen in the current pandemic scenarios.

Quality assessment of selected co-trimoxazole suspension brands marketed in Nairobi County, Kenya

INTRODUCTION

Quality of medicines in both developed and developing countries is sometimes compromised due to infiltration of counterfeit, substandard or degraded medicines into the markets. It is a public health concern as poor quality medicines endanger public health where patients are exposed to chemical toxins and/or sub-therapeutic doses. This could lead to reduced treatment efficacy and promote development of drug resistance. Co-trimoxazole, a fixed dose combination of sulfamethoxazole and trimethoprim, is a broad spectrum for bacterial diseases and is also used as a prophylaxis for opportunistic infections in HIV infected individuals. This study evaluated quality of selected co-trimoxazole suspension brands marketed in Nairobi County, Kenya.

METHODS

A total of 106 samples were collected, categorized into 15 brands and evaluated for active pharmaceutical ingredient content (API) and pH following United States Pharmacopeia. Assay for API was conducted using High Performance Liquid Chromatography. Results were compared with pharmacopeia references. Visual examination of labels and confirmation of retention status of the brands with Pharmacy and Poisons Board retention register was carried out.

RESULTS

The samples were primarily of local origin (86.7%). On October 23, 2019, retention status of six of the fifteen brands documented were no longer listed in the Pharmacy and Poisons Board retention register. Of the 106 samples tested 70.6% and 86.8% were compliant with United States Pharmacopeia (USP) specifications for pH and API respectively while 84.0% adhered to packaging and labelling requirements.

CONCLUSION

This study has demonstrated that majority of co-trimoxazole suspensions tested were compliant with USP requirements. Additionally, it has provided evidence of poor quality co-trimoxazole medicines that could compromise treatment of infectious diseases in children. This emphasizes the need for regular quality assurance tests to ensure only quality medicines are in the market.

Neurotransmitter System-Targeting Drugs Antagonize Growth of the Q Fever Agent, Coxiella burnetii, in Human Cells

Coxiella burnetii is a highly infectious, intracellular, Gram-negative bacterial pathogen that causes human Q fever, an acute flu-like illness that can progress to chronic endocarditis. C. burnetii is transmitted to humans via aerosols and has long been considered a potential biological warfare agent. Although antibiotics, such as doxycycline, effectively treat acute Q fever, a recently identified antibiotic-resistant strain demonstrates the ability of C. burnetii to resist traditional antimicrobials, and chronic disease is extremely difficult to treat with current options. These findings highlight the need for new Q fever therapeutics, and repurposed drugs that target eukaryotic functions to prevent bacterial replication are of increasing interest in infectious disease. To identify this class of anti-C. burnetii therapeutics, we screened a library of 727 FDA-approved or late-stage clinical trial compounds using a human macrophage-like cell model of infection. Eighty-eight compounds inhibited bacterial replication, including known antibiotics, antipsychotic or antidepressant treatments, antihistamines, and several additional compounds used to treat a variety of conditions. The majority of identified anti-C. burnetii compounds target host neurotransmitter system components. Serotoninergic, dopaminergic, and adrenergic components are among the most highly represented targets and potentially regulate macrophage activation, cytokine production, and autophagy. Overall, our screen identified multiple host-directed compounds that can be pursued for potential use as anti-C. burnetii drugs.

IMPORTANCECoxiella burnetii causes the debilitating disease Q fever in humans. This infection is difficult to treat with current antibiotics and can progress to long-term, potentially fatal infection in immunocompromised individuals or when treatment is delayed. Here, we identified many new potential treatment options in the form of drugs that are either FDA approved or have been used in late-stage clinical trials and target human neurotransmitter systems. These compounds are poised for future characterization as nontraditional anti-C. burnetii therapies.

Chemotherapeutic Strategies for Combating Staphylococcus aureus Infections

Staphylococcus aureus is a prominent human pathogen that causes nosocomial and community acquired infections. The accelerating emergence and prevalence of staphylococcal infections have grotesque health consequences which are mostly due to its anomalous capability to acquire drug resistance and scarcity of novel classes of antibacterials. Many combating therapies are centered on primary targets of S. aureus which are cell envelope, ribosomes and nucleic acids. This review describes various chemotherapeutic strategies for combating S. aureus infections which includes monotherapy, combination drug therapy, phage endolysin therapy, lysostaphins and antibacterial drones. Monotherapy has dwindled in due course of time but combination therapy, endolysin therapy, lysostaphin and antibacterial drones are emerging alternatives which efficiently conquer the shortcomings of monotherapy. Combinations of more than one antibiotic agents or combination of adjuvant with antibiotics provide a synergistic approach to combat infections causing pathogenic strains. Phage endolysin therapy and lysostaphin are also presents as possible alternatives to conventional antibiotic therapies. Antibacterial Drones goes a step further by specifically targeting the virulence genes in bacteria giving them a certain advantage over existing antibacterial strategies. But the challenge remains on the better understanding of these strategies for executing and implementing them in health sector. In this day and age, most of the S. aureus strains are resistant to ample number of antibiotics, so there is an urgent need to overcome such multidrug resistant strains for the welfare of our community.

Bacterial susceptibility patterns to cotrimoxazole in urinary tract infections of outpatients and inpatients in Jakarta, Indonesia

BACKGROUND Cotrimoxazole, which has been one of the drugs of choice for urinary tract infections (UTIs) since 1960, must be evaluated to determine whether it is still a relevant drug for this use. This study aimed to assess the susceptibility patterns to cotrimoxazole of the bacteria that cause UTIs from urine samples of female outpatients (community-acquired [CA]-UTI) and inpatients (hospital-acquired [HA]-UTI) in Jakarta. METHODS This study was conducted from December 2014 to December 2015. Susceptibility testing of bacteria causing UTIs was conducted on 27 of 311 female outpatient urine samples collected from six clinics in Jakarta, and secondary data susceptibility testing was performed on 27 of 107 urine samples of inpatients from hospitals in Jakarta. These samples were examined in the Clinical Microbiology Laboratory, Faculty of Medicine, Universitas Indonesia, Cipto Mangunkusumo Hospital. RESULTS Susceptibility to cotrimoxazole was reported in 83% of the bacteria causing UTIs in CA-UTI and 44% of the bacteria in HA-UTI patients. Klebsiella pneumoniae was the most common cause of CA-UTI, with all isolates susceptible to cotrimoxazole (100%). Conversely, Escherichia coli was the most common cause of HA-UTI but was only susceptible in some isolates (44%). Bacteria from CA-UTI patients were almost twice as susceptible to cotrimoxazole compared with HA-UTI patients (p = 0.003). CONCLUSIONS Based on the susceptibility patterns identified, cotrimoxazole can be used as a treatment for CA-UTI but not for HA-UTI patients in Jakarta, Indonesia.

Advances in Cyclosporiasis Diagnosis and Therapeutic Intervention

Cyclosporiasis is caused by the coccidian parasite Cyclospora cayetanensis and is associated with large and complex food-borne outbreaks worldwide. Associated symptoms include severe watery diarrhea, particularly in infants, and immune dysfunction. With the globalization of human food supply, the occurrence of cyclosporiasis has been increasing in both food growing and importing countries. As well as being a burden on the health of individual humans, cyclosporiasis is a global public health concern. Currently, no vaccine is available but early detection and treatment could result in a favorable clinical outcome. Clinical diagnosis is based on cardinal clinical symptoms and conventional laboratory methods, which usually involve microscopic examination of wet smears, staining tests, fluorescence microscopy, serological testing, or DNA testing for oocysts in the stool. Detection in the vehicle of infection, which can be fresh produce, water, or soil is helpful for case-linkage and source-tracking during cyclosporiasis outbreaks. Treatment with trimethoprim-sulfamethoxazole (TMP-SMX) can evidently cure C. cayetanensis infection. However, TMP-SMX is not suitable for patients having sulfonamide intolerance. In such case ciprofloxacin, although less effective than TMP-SMX, is a good option. Another drug of choice is nitazoxanide that can be used in the cases of sulfonamide intolerance and ciprofloxacin resistance. More epidemiological research investigating cyclosporiasis in humans should be conducted worldwide, to achieve a better understanding of its characteristics in this regard. It is also necessary to establish in vitro and/or in vivo protocols for cultivating C. cayetanensis, to facilitate the development of rapid, convenient, precise, and economical detection methods for diagnosis, as well as more effective tracing methods. This review focuses on the advances in clinical features, diagnosis, and therapeutic intervention of cyclosporiasis.

Cyclospora cayetanensis infection in humans: biological characteristics, clinical features, epidemiology, detection method and treatment

Cyclospora cayetanensis, a coccidian parasite that causes protracted and relapsing gastroenteritis, has a short recorded history. At least 54 countries have documented C. cayetanensis infections and 13 of them have recorded cyclosporiasis outbreaks. Cyclospora cayetanensis infections are commonly reported in developing countries with low-socioeconomic levels or in endemic areas, although large outbreaks have also been documented in developed countries. The overall C. cayetanensis prevalence in humans worldwide is 3.55%. Among susceptible populations, the highest prevalence has been documented in immunocompetent individuals with diarrhea. Infections are markedly seasonal, occurring in the rainy season or summer. Cyclospora cayetanensis or Cyclospora-like organisms have also been detected in food, water, soil and some other animals. Detection methods based on oocyst morphology, staining and molecular testing have been developed. Treatment with trimethoprim-sulfamethoxazole (TMP-SMX) effectively cures C. cayetanensis infection, whereas ciprofloxacin is less effective than TMP-SMX, but is suitable for patients who cannot tolerate co-trimoxazole. Here, we review the biological characteristics, clinical features, epidemiology, detection methods and treatment of C. cayetanensis in humans, and assess some risk factors for infection with this pathogen.

Evaluation of treatment options for methicillin-resistant Staphylococcus aureus infections in the obese patient

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major cause of infection in both the hospital and community setting. Obesity is a risk factor for infection, and the prevalence of this disease has reached epidemic proportions worldwide. Treatment of infections in this special population is a challenge given the lack of data on the optimal antibiotic choice and dosing strategies, particularly for treatment of MRSA infections. Obesity is associated with various physiological changes that may lead to altered pharmacokinetic parameters. These changes include altered drug biodistribution, elimination, and absorption. This review provides clinicians with a summary of the literature pertaining to the pharmacokinetic and pharmacodynamic considerations when selecting antibiotic therapy for the treatment of MRSA infections in obese patients.

Human cyclosporiasis

Cyclospora species are socioeconomically important protistan pathogens. Cyclospora cayetanensis is usually transmitted via food or water to a human host via the faecal-oral route and can cause the gastrointestinal disease cyclosporiasis, which can be complicated by extra-intestinal disorders, particularly in immune-compromised people. Although more than 2 million children die each year from diarrhoeal diseases worldwide, it is not known to what extent cyclosporiasis is involved. Few epidemiological data are available on Cyclospora as a water-borne and food-borne pathogen in both underprivileged communities and developed countries. To gain an improved understanding of human cyclosporiasis, this Review describes the background of Cyclospora, summarises salient aspects of the pathogenesis, epidemiology, diagnosis, treatment, and control of cyclosporiasis, and explores what is known about its prevalence and geographical distribution. The findings show that the effect on human health of cyclosporiasis is likely underestimated, and recommendations are made about areas of future research and the prevention and control of this disease within an international collaborative context.

Trimethoprim-sulfamethoxazole vs. colistin or ampicillin-sulbactam for the treatment of carbapenem-resistant Acinetobacter baumannii: A retrospective matched cohort study

OBJECTIVES

This study aimed to assess the effectiveness of trimethoprim-sulfamethoxazole (TMP/SMX) as monotherapy for the treatment of carbapenem-resistant Acinobacter baumannii (A. baumannii) (CRAB) infections.

METHODS

This retrospective cohort study included patients receiving TMP/SMX as the main treatment for severe infections caused by CRAB, who were matched with patients treated with colistin or ampicillin-sulbactam (AMP/SUL) by age, Charlson score, department, and source of infection. Outcomes were compared among all patients and in a subgroup of propensity-score (PS) matched patients. The PS matching was performed using a match tolerance of 0.15 with replacement.

RESULTS

Fifty-three patients treated with TMP/SMX and 83 matched patients treated with colistin or AMP/SUL were included. Variables that were independently significantly associated with TMP/SMX treatment included admission for infection and septic shock, while abnormal cognition on admission and intensive care unit admission were associated with colistin or AMP/SUL treatment. All-cause 30-day mortality was lower with TMP/SMX compared with the comparator antibiotics among all patients (24.5%, 13 of 53 vs. 38.6%, 32 of 83, P=0.09) and in the PS-matched subgroup (29%, 9 of 31 vs. 55.2% 16 of 29, P=0.04). Treatment failure rates were not significantly different overall (34%, 18 of 53 vs. 42.4%, 35 of 83, P=0.339) and in the PS-matched subgroup (35.5%, 11 of 31 vs. 44.8%, 13 of 29, P=0.46). Time to clinical stability and hospitalization duration were significantly shorter with TMP/SMX. Patients treated with TMP/SMX probably had less severe infections than those treated with other antibiotics, even after matching.

CONCLUSIONS

TMP/SMX might be a valuable treatment option for TMP/SMX-susceptible CRAB infections. Given the very limited available treatment options, further studies assessing its effectiveness and safety are necessary.

Antibiotic resistance in Staphylococcus aureus. Current status and future prospects

The major targets for antibiotics in staphylococci are (i) the cell envelope, (ii) the ribosome and (iii) nucleic acids. Several novel targets emerged from recent targeted drug discovery programmes including the ClpP protease and FtsZ from the cell division machinery. Resistance can either develop by horizontal transfer of resistance determinants encoded by mobile genetic elements viz plasmids, transposons and the staphylococcal cassette chromosome or by mutations in chromosomal genes. Horizontally acquired resistance can occur by one of the following mechanisms: (i) enzymatic drug modification and inactivation, (ii) enzymatic modification of the drug binding site, (iii) drug efflux, (iv) bypass mechanisms involving acquisition of a novel drug-resistant target, (v) displacement of the drug to protect the target. Acquisition of resistance by mutation can result from (i) alteration of the drug target that prevents the inhibitor from binding, (ii) derepression of chromosomally encoded multidrug resistance efflux pumps and (iii) multiple stepwise mutations that alter the structure and composition of the cell wall and/or membrane to reduce drug access to its target. This review focuses on development of resistance to currently used antibiotics and examines future prospects for new antibiotics and informed use of drug combinations.

Stenotrophomonas maltophilia Serine Protease StmPr1 Induces Matrilysis, Anoikis, and Protease-Activated Receptor 2 Activation in Human Lung Epithelial Cells

Stenotrophomonas maltophilia is an emerging, opportunistic nosocomial pathogen that can cause severe disease in immunocompromised individuals. We recently identified the StmPr1 and StmPr2 serine proteases to be the substrates of the Xps type II secretion system in S. maltophilia strain K279a. Here, we report that a third serine protease, StmPr3, is also secreted in an Xps-dependent manner. By constructing a panel of protease mutants in strain K279a, we were able to determine that StmPr3 contributes to the previously described Xps-mediated rounding and detachment of cells of the A549 human lung epithelial cell line as well as the Xps-mediated degradation of fibronectin, fibrinogen, and the cytokine interleukin-8 (IL-8). We also determined that StmPr1, StmPr2, and StmPr3 account for all Xps-mediated effects toward A549 cells and that StmPr1 contributes the most to Xps-mediated activities. Thus, we purified StmPr1 from the S. maltophilia strain K279a culture supernatant and evaluated the protease's activity toward A549 cells. Our analyses revealed that purified StmPr1 behaves more similarly to subtilisin than to trypsin. We also determined that purified StmPr1 likely induces cell rounding and detachment of A549 cells by targeting cell integrin-extracellular matrix connections (matrilysis) as well as adherence and tight junction proteins for degradation. In this study, we also identified anoikis as the mechanism by which StmPr1 induces the death of A549 cells and found that StmPr1 induces A549 IL-8 secretion via activation of protease-activated receptor 2. Altogether, these results suggest that the degradative and cytotoxic activities exhibited by StmPr1 may contribute to S. maltophilia pathogenesis in the lung by inducing tissue damage and inflammation.

Risk factors for hospital acquisition of trimethoprim-sulfamethoxazole resistant Stenotrophomonas maltophilia in adults: A matched case-control study

BACKGROUND/PURPOSE

The emergence of trimethoprim-sulfamethoxazole resistant Stenotrophomonas maltophilia (TSRSM) represents a serious threat to patients. The aim of current study was to identify risk factors associated with hospital-acquired TSRSM occurrence in adult inpatients.

METHODS

We conducted a matched case-control study in Tri-Service General Hospital, Taipei, Taiwan. From January 2014 through June 2015, case patients with TSRSM and control patients with trimethoprim-sulfamethoxazole susceptible S. maltophilia (TSSSM) during hospitalization were identified. Control patients were matched with TSRSM cases for age (within five years), sex, and site of isolation at a ratio of 1:1.

RESULTS

A total of 266 patients were included in our study (133 cases and 133 matched controls). Bivariable analysis showed that previous exposure to fluoroquinolone [odds ratio (OR), 2.693; 95% confidence interval (CI, 1.492-5.884; p = 0.002)], length of intensive care unit stay (OR, 1.015 per day; 95% CI, 1.001-1.030; p = 0.041), and length of hospital stay (OR, 1.012 per day; 95% CI, 1.002-1.023; p = 0.018) prior to S. maltophilia isolation were associated with TSRSM occurrence. A multivariable analysis showed that previous exposure to fluoroquinolone (OR, 3.158; 95% CI, 1.551-6.430; p = 0.002) was an independent risk factor for TSRSM occurrence after adjustment.

CONCLUSION

Previous fluoroquinolone use was an independent risk factor for hospital-acquired TSRSM occurrence in adult inpatients, suggesting that judicious administration of fluoroquinolone may be important for limiting TSRSM occurrence.

Antibiotic sensitivity pattern of indigenous lactobacilli isolated from curd and human milk samples

The gut microbiota plays a vital role in host well-being and lactic acid bacteria (LAB) have gained an overwhelming attention as health promoter. This perception has evolved from traditional dairy products to a money-spinning market of probiotics. The safety of probiotics is coupled to their intended use and LAB may act as pool of antimicrobial resistance genes that could be transferred to pathogens, either in food matrix or in gastrointestinal tract, which could be detrimental to host. This study evaluated the antibiotic susceptibility patterns of LAB isolated from curd (20) and human milk (11) samples. Antibiotic susceptibility was determined against 26 common antibiotics, following reference disc diffusion assay. A varied response in terms of susceptibility and resistance towards antibiotics was recorded. Among curd isolates, D7 (Lactobacillus plantarum) was the most resistant followed by D4, D8, D10 and D25. Among human milk isolates, HM-1 (L. casei) showed the highest resistance profile. All LAB isolates displayed high susceptibility pattern towards imipenem and meropenem. In general, high resistivity was exhibited by human milk isolates. The present study showed that antibiotic resistance is widespread among different lactobacilli, which may pose a food safety concern. Therefore, antibiotic sensitivity should be considered as a vital tool for safety assessment of probiotics.

Emergence of Carbapenem Resistant Non-Fermenting Gram-Negative Bacilli Isolated in an ICU of a Tertiary Care Hospital

INTRODUCTION

The emergence and spread of Multi-Drug Resistant (MDR) Non-Fermenting Gram-Negative Bacilli (NFGNB) in Intensive Care Units (ICU) and their genetic potential to transmit diverse antibiotic resistance regardless of their ability to ferment glucose poses a major threat in hospitals. The complex interplay of clonal spread, persistence, transmission of resistance elements and cell-cell interaction leads to the difficulty in controlling infections caused by these multi drug-resistant strains. Among non-fermenting Gram-negative rods, the most clinically significant species Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia are increasingly acquiring resistant to carbapenems. Carbapenems once considered as a backbone of treatment of life threatening infections appears to be broken as the resistance to carbapenems is on rise.

AIM

To document the prevalence of carbapenem resistance in non-fermenting Gram-negative bacilli isolated from patients with respiratory tract infections in the ICU of Himalayan Institute of Medical Sciences, Dehradun.

MATERIALS AND METHODS

This is a cross-sectional study conducted in ICU patients between October 2015 to March 2016. A total of 366 lower respiratory tract samples were collected from 356 patients with clinical evidence of lower respiratory tract infections in form of Endotracheal (ET) aspirate, Tracheal Tube (TT) aspirate and Bronchoalveolar Lavage (BAL) specimen. Organism identification and the susceptibility testing was done by using an automated system VITEK 2.

RESULTS

Out of 366 samples received 99 NFGNB were isolated and most common sample was ET aspirate sample 256 (64.5%). Acinetobacter baumannii was the most common NFGNB isolated 63 (63.63%) followed by Pseudomonas aeruginosa 25 (25.25%), Elizabethkingia meningoseptica seven (7.07%) and Strenotrophomonas maltophilia four (4.04%). We observed that 90.5% Acinetobacter baumannii were resistant to imipenem and 95.2% resistant to meropenem, Pseudomonas aeruginosa came out to be 52% resistant to imipenem and 56% resistant to meropenem while Stenotrophomonas maltophilia and Elizabethkingia meningoseptica were 100% resistant to carbapenems as they are intrinsically resistant to carbapenems.

CONCLUSION

The resistance rate of carbapenems for NFGNB infections is very high in our study and variable in different regions. Overall carbapenem resistance is on rise. So, the infection control team and microbiologist needs to work together to determine the risk carried by multi drug resistant non-fermenting gram-negative infections and the resistance surveillance programs are mandatory to control these bacteria in ICU settings.

The potential role of trimethoprim-sulfamethoxazole in the treatment of drug-resistant tuberculosis

Tuberculosis (TB) remains a serious public health threat worsened by emerging drug resistance. Mycobacterium tuberculosis has become resistant not only to front-line drugs but also to second-line antimicrobials directed at drug-resistant TB. Renewed efforts are devoted for the development of new antibiotics active against TB. Also, repurposing of other antibiotics is being explored to shorten the time to develop new drugs against M. tuberculosis. As a result, trimethoprim-sulfamethoxazole (SXT) has emerged as a potential new option to treat drug-resistant TB. SXT has been found to be surprisingly active against drug-resistant M. tuberculosis, not only in vitro but also in vivo. The potential role of SXT for the treatment of multidrug resistant/extensively drug resistant TB might be explored in further clinical evaluations.

Type II Secretion-Dependent Degradative and Cytotoxic Activities Mediated by Stenotrophomonas maltophilia Serine Proteases StmPr1 and StmPr2

Stenotrophomonas maltophilia is an emerging opportunistic pathogen that primarily causes pneumonia and bacteremia in immunocompromised individuals. We recently reported that S. maltophilia strain K279a encodes the Xps type II secretion system and that Xps promotes rounding, actin rearrangement, detachment, and death in the human lung epithelial cell line A549. Here, we show that Xps-dependent cell rounding and detachment occur with multiple human and murine cell lines and that serine protease inhibitors block Xps-mediated rounding and detachment of A549 cells. Using genetic analysis, we determined that the serine proteases StmPr1 and StmPr2, which were confirmed to be Xps substrates, are predominantly responsible for secreted proteolytic activities exhibited by strain K279a, as well as the morphological and cytotoxic effects on A549 cells. Supernatants from strain K279a also promoted the degradation of type I collagen, fibrinogen, and fibronectin in a predominantly Xps- and protease-dependent manner, although some Xps-independent degradation of fibrinogen was observed. Finally, Xps, and predominantly StmPr1, degraded interleukin 8 (IL-8) secreted by A549 cells during coculture with strain K279a. Our findings indicate that while StmPr1 and StmPr2 are predominantly responsible for A549 cell rounding, extracellular matrix protein degradation, and IL-8 degradation, additional Xps substrates also contribute to these activities. Altogether, our data provide new insight into the virulence potential of the S. maltophilia Xps type II secretion system and its StmPr1 and StmPr2 substrates.

No Development of Imipenem Resistance in Pneumonia Caused by Escherichia coli

BACKGROUND

Antibiotic resistance continues to rise due to the increased number of antibiotic prescriptions and is now a major threat to public health. In particular, there is an increase in antibiotic resistance to Escherichia coli according to the latest reports.

TRIAL DESIGN

This article examines, retrospectively, antibiotic resistance in patients with community- and nosocomial-acquired pneumonia caused by E coli.

METHODS

The data of all patients with community- and nosocomial-acquired pneumonia caused by E coli were collected from the hospital charts at the HELIOS Clinic, Witten/Herdecke University, Wuppertal, Germany, within the study period 2004 to 2014. An antibiogram was performed for the study patients with pneumonia caused by E coli. Antimicrobial susceptibility testing was performed for the different antibiotics that have been consistently used in the treatment of patients with pneumonia caused by E coli. All demographic, clinical, and laboratory data of all of the patients with pneumonia caused by E coli were collected from the patients' records.

RESULTS

During the study period of January 1, 2004 to August 12, 2014, 135 patients were identified with community- and nosocomial-acquired pneumonia affected by E coli. These patients had a mean age of 72.5 ± 11.6 (92 [68.1%, 95% CI 60.2%-76.0%] males and 43 [31.9%, 95% CI 24.0%-39.8%] females). E coli had a high resistance rate to ampicillin (60.7%), piperacillin (56.3%), ampicillin-sulbactam (44.4%), and co-trimoxazole (25.9%). No patients with pneumonia caused by E coli showed resistance to imipenem (P < 0.0001).

CONCLUSION

E coli was resistant to many of the typically used antibiotics. No resistance was detected toward imipenem in patients with pneumonia caused by E coli.

Trimethoprim/sulfamethoxazole for Acinetobacter spp.: A review of current microbiological and clinical evidence

Clinicians nowadays are confronted with an epidemic of multidrug-resistant (MDR) Acinetobacter infections and are forced to consider every treatment alternative, including older antibiotic agents, not conventionally used. This review aimed to evaluate the published evidence on the antimicrobial activity and clinical effectiveness of trimethoprim/sulfamethoxazole (TMP-SMX) against Acinetobacter spp. Selected in vitro studies included antimicrobial surveillance reports, microbiological studies regarding the activity of TMP-SMX against MDR Acinetobacter isolates, and clinical studies published after the year 2000. Non-susceptibility rates for Acinetobacter spp. in surveillance studies ranged from 4% to 98.2%; in 23 of 28 studies, non-susceptibility to TMP-SMX was >50% and in a subset of 15 studies non-susceptibility was >70%. In studies regarding MDR Acinetobacter spp., non-susceptibility rates ranged from 5.9% to 100%; however, 19 of 21 studies reported >70% non-susceptibility. Extensively drug-resistant Acinetobacter baumannii complex had total (100%) resistance in five of six studies. Carbapenem-resistant Acinetobacter spp. had non-susceptibility rates to TMP-SMX of >80% in 22 of 26 studies. One study on polymyxin-resistant A. baumannii showed a susceptibility rate of 54.2% (13/24). Only seven case reports evaluated TMP-SMX for Acinetobacter spp. infections, mainly in combination with other agents; all cases were deemed therapeutic successes. Although TMP-SMX is not usually active against Acinetobacter spp., it might be considered in cases where there are no other options.

The expanding role of co-trimoxazole in developing countries

Co-trimoxazole is an inexpensive, broad-spectrum antimicrobial drug that is widely used in developing countries. Before antiretroviral therapy (ART) scale-up, co-trimoxazole prophylaxis reduced morbidity and mortality in adults and children with HIV by preventing bacterial infections, diarrhoea, malaria, and Pneumocystis jirovecii pneumonia, despite high levels of microbial resistance. Co-trimoxazole prophylaxis reduces early mortality by 58% (95% CI 39-71) in adults starting ART. Co-trimoxazole provides ongoing protection against malaria and non-malaria infections after immune reconstitution in ART-treated individuals in sub-Saharan Africa, leading to a change in WHO guidelines, which now recommend long-term co-trimoxazole prophylaxis for adults and children in settings with a high prevalence of malaria or severe bacterial infections. Co-trimoxazole prophylaxis is recommended for HIV-exposed infants from age 4-6 weeks; however, the risks and benefits of co-trimoxazole during infancy are unclear. Co-trimoxazole prophylaxis reduces anaemia and improves growth in children with HIV, possibly by reducing inflammation, either through direct immunomodulatory activity or through effects on the intestinal microbiota leading to reduced microbial translocation. Ongoing trials are now assessing the ability of adjunctive co-trimoxazole to reduce mortality in children after severe anaemia or severe acute malnutrition. In this Review, we discuss the mechanisms of action, benefits and risks, and clinical trials of co-trimoxazole in developing countries.

Cotrimoxazole - optimal dosing in the critically ill

The optimum dosage regimen for cotrimoxazole in the treatment of life threatening infections due to susceptible organisms encountered in critically ill patients is unclear despite decades of the drug's use. Therapeutic drug monitoring to determine the appropriate dosing for successful infection eradication is not widely available. The clinician must utilize published pharmacokinetic, pharmacodynamic, and effective inhibitory concentration information to determine potential dosing regimens for individual patients when treating specific pathogens. Using minimum inhibitory concentrations known to successfully block growth for target pathogens, the pharmacokinetics of both trimethoprim and sulfamethoxazole can be utilized to establish empiric dosing regimens for critically ill patients while considering organ of clearance impairment. The author's recommendations for appropriate dosing regimens are forwarded based on these parameters.

New strategies against Stenotrophomonas maltophilia: a serious worldwide intrinsically drug-resistant opportunistic pathogen

Stenotrophomonas maltophilia is a worldwide human opportunistic pathogen associated with serious infections in humans, and is most often recovered from respiratory tract infections. In addition to its intrinsic drug resistance, this organism may acquire resistance via multiple molecular mechanisms. New antimicrobial strategies are needed to combat S. maltophilia infections, particularly in immunocompromised patients, cystic fibrosis patients with polymicrobial infections of the lung, and in patients with chronic infections. This editorial reports on newer drugs and antimicrobial strategies and their potential for use in treatment of S. maltophilia infections, the development of new technologies to detect this organism, and identifies strategies currently in use to reduce transmission of this pathogen.

Optimizing antimicrobial prescribing: Are clinicians following national trends in methicillin-resistant staphylococcus aureus (MRSA) infections rather than local data when treating MRSA wound infections

Background

Clinicians often prescribe antimicrobials for outpatient wound infections before culture results are known. Local or national MRSA rates may be considered when prescribing antimicrobials. If clinicians prescribe in response to national rather than local MRSA trends, prescribing may be improved by making local data accessible. We aimed to assess the correlation between outpatient trends in antimicrobial prescribing and the prevalence of MRSA wound infections across local and national levels.

Methods

Monthly MRSA positive wound culture counts were obtained from The Surveillance Network, a database of antimicrobial susceptibilities from clinical laboratories across 278 zip codes from 1999–2007. Monthly outpatient retail sales of linezolid, clindamycin, trimethoprim-sulfamethoxazole and cephalexin from 1999–2007 were obtained from the IMS Health Xponent^TM database. Rates were created using census populations. The proportion of variance in prescribing that could be explained by MRSA rates was assessed by the coefficient of determination (R²), using population weighted linear regression.

Results

107,215 MRSA positive wound cultures and 106,641,604 antimicrobial prescriptions were assessed. The R² was low when zip code-level antimicrobial prescription rates were compared to MRSA rates at all levels. State-level prescriptions of clindamycin and linezolid were not correlated with state MRSA rates. The variance in state-level prescribing of clindamycin and linezolid was correlated with national MRSA rates (clindamycin R² = 0.17, linezolid R² = 0.22).

Conclusions

Clinicians may rely on national, not local MRSA data when prescribing clindamycin and linezolid for wound infections. Providing local resistance data to prescribing clinicians may improve antimicrobial prescribing and would be a possible target for future interventions.

Cotrimoxazole-induced hypoglycaemia in a patient with churg-strauss syndrome

Cotrimoxazole is a commonly used antimicrobial agent which is traditionally indicated in the management of pneumocystis infection of which HIV and immunosuppressed individuals are at high risk. Furthermore, it can be used on the long term for prophylactic indications. Hypoglycaemia following commencement of cotrimaoxazole is a rare adverse effect which was first described in 1988. We describe a case of hypoglycaemia shortly following initiation of cotrimoxazole indicated as long-term prophylaxis on a background of Churg-Strauss syndrome. The patient was symptomatic for hypoglycaemia despite simultaneous use of high-dose prednisolone; however, the hypoglycaemia did not require a hospital admission. We will explore the risk factors, monitoring requirements, and the mechanism by which co-trimoxazole induces hypoglycaemia.

Has the emergence of community-associated methicillin-resistant Staphylococcus aureus increased trimethoprim-sulfamethoxazole use and resistance?: a 10-year time series analysis

There are an increasing number of indications for trimethoprim-sulfamethoxazole use, including skin and soft tissue infections due to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). Assessing the relationship between rates of use and antibiotic resistance is important for maintaining the expected efficacy of this drug for guideline-recommended conditions. Using interrupted time series analysis, we aimed to determine whether the 2005 emergence of CA-MRSA and recommendations of trimethoprim-sulfamethoxazole as the preferred therapy were associated with changes in trimethoprim-sulfamethoxazole use and susceptibility rates. The data from all VA Boston Health Care System facilities, including 118,863 inpatient admissions, 6,272,661 outpatient clinic visits, and 10,138 isolates were collected over a 10-year period. There was a significant (P = 0.02) increase in trimethoprim-sulfamethoxazole prescriptions in the post-CA-MRSA period (1,605/year) compared to the pre-CA-MRSA period (1,538/year). Although the overall susceptibility of Escherichia coli and Proteus spp. to trimethoprim-sulfamethoxazole decreased over the study period, the rate of change in the pre- versus the post-CA-MRSA period was not significantly different. The changes in susceptibility rates of S. aureus to trimethoprim-sulfamethoxazole and to methicillin were also not significantly different. The CA-MRSA period is associated with a significant increase in use of trimethoprim-sulfamethoxazole but not with significant changes in the rates of susceptibilities among clinical isolates. There is also no evidence for selection of organisms with increased resistance to other antimicrobials in relation to increased trimethoprim-sulfamethoxazole use.