Multiple Drug Resistant Pathogens Research Articles

Current controversies in equine antimicrobial therapy

SummaryControversies exist regarding the use, misuse and potential overuse of antimicrobial treatments in foals and adults. When antimicrobials are required for treatment of infectious diseases, veterinarians should follow a logical approach and not simply reach for the newest drug. Targeted, single drug therapy is probably best, and culture and sensitivity testing should be undertaken. The most likely infectious agent, potential drug toxicities, and age‐appropriate dose and route should be considered. The development of an increasing number of different multiple drug resistant pathogens requires that veterinarians use antimicrobial drugs responsibly to protect veterinary patients and the public at large.

The Experience of a Novel Glycylcycline Antibiotic for a Patient with Infection Caused by Multiple Drug-Resistant Pathogens: What is the Benefit?

We report a 75-year-old man with septic shock induced by ventilator-associated pneumonia caused by multiple drug-resistant Acinetobacter baumannii and catheter-related infection by vancomycin-resistant enterococci. He failed to respond to the initial management, including antibiotics (linezolid, imipenem, sulbactam and colistin) and hemodynamic-guided fluid challenge. However, his condition improved dramatically after the antibiotic regimen was changed to tigecycline and ceftazidime. In addition to the superiority of the antibacterial effect of tigecycline, fluid control can be achieved more easily while using a single antibiotic instead of multiple drugs, which is also important for care of a critically ill elderly man with compromised cardiorespiratory or renal function. Here, we present a patient infected with multiple drug-resistant pathogens, who improved clinically after being treated with tigecycline, to demonstrate the benefits of this antibiotic.

Feast or famine: the global regulator DasR links nutrient stress to antibiotic production by Streptomyces

Members of the soil-dwelling prokaryotic genus Streptomyces produce many secondary metabolites, including antibiotics and anti-tumour agents. Their formation is coupled with the onset of development, which is triggered by the nutrient status of the habitat. We propose the first complete signalling cascade from nutrient sensing to development and antibiotic biosynthesis. We show that a high concentration of N-acetylglucosamine-perhaps mimicking the accumulation of N-acetylglucosamine after autolytic degradation of the vegetative mycelium-is a major checkpoint for the onset of secondary metabolism. The response is transmitted to antibiotic pathway-specific activators through the pleiotropic transcriptional repressor DasR, the regulon of which also includes all N-acetylglucosamine-related catabolic genes. The results allowed us to devise a new strategy for activating pathways for secondary metabolite biosynthesis. Such 'cryptic' pathways are abundant in actinomycete genomes, thereby offering new prospects in the fight against multiple drug-resistant pathogens and cancers.

Antimicrobial susceptibility among aerobic bacteria isolates in the Intensive Care Unit of a tertiary regional hospital in Trinidad & Tobago.

Background: There are variations in the epidemiology, prevalent pathogens and antimicrobial susceptibility patterns of infections in the intensive care unit (ICU) from one health care facility to another, hospital to hospital, and country to country. This study was undertaken to determine and document the frequency of occurrence of microbial isolates and their antibiotic susceptibility pattern from clinical specimens received from the ICU of a tertiary regional hospital in Trinidad and Tobago. Materials & methods: Microbial isolates from patients admitted to the ICU of the Eric Williams Medical Sciences Complex over a 4-year period were investigated. Automated systems and Standard microbiological methods including BACTEC 9240 (Becton-Dickinson Microbiology Systems), MicroScan Walk Away 96 SI (Dade Behring, USA), modified Kirby Bauer disc diffusion and Etest were used. Clinical specimens from 1,128 patients admitted to the ICU during the study period were processed, and 869 pathogens were recovered from 638 positive cultures. Results: The most frequent pathogens were recovered from respiratory tract specimens, while the Enterobacteriaceae groups of organisms were the most prevalent isolates. Except for Acinetobacter species that exhibit a consistent multiple drug resistant patterns, all the pathogens showed variable susceptibility to the readily available antimicrobials in the country. A 4.2% incidence rate of ESBL producers was encountered among the K. pneumoniae and E. coli isolates from the unit. Methicillin-resistant S. aureus was noted to be on the decline in this unit, but we observed the emergence of genuine vancomycin resistant methicillin-resistant S. aureus.Conclusions: Although Enterobacteriaceae and Pseudomonas aeruginosa were the most frequent isolates, there are still sufficient treatment options for patients infected with these organisms in the unit. Continuous surveillance and monitoring for multiple drug resistant pathogens in the unit should still be paramount especially with the ongoing establishment of the National Oncology Center and National Organ Transplant Units at the complex. There is an equal need for further studies on the determinants of drug resistance in this unit.

Nocathiacins, new thiazolyl peptide antibiotics from Nocardia sp. I. Taxonomy, fermentation and biological activities.

Thiazolyl peptide antibiotics, nocathiacin I, II and III, were identified in a culture of Nocardia sp. WW-12651 (ATCC 202099). They exhibit potent in vitro activity (ng/ml) against a wide spectrum of gram-positive bacteria, including multiple-drug resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), multi-drug resistant Enterococcus faecium (MREF) and fully penicillin-resistant Streptococcus pneumoniae (PRSP), and demonstrate excellent in vivo efficacy in a systemic Staphylococcus aureus infection mice model.

Antibacterials for the prophylaxis and treatment of bacterial endocarditis in children.

Although the overall incidence of infective endocarditis in the paediatric population is considered to be low, over the last 20 years a rising trend in infective endocarditis has been observed among children. This could be due to several reasons including the availability of improved diagnostic techniques, use of continuous central venous catheters and cardiac implants increasing the risk of infection, and the survival of a greater number of infants with congenital heart disease as a result of improved medical management. The predominant causative organisms of paediatric endocarditis include staphylococci and streptococci. There is increased concern surrounding the emergence of endocarditis in children caused by methicillin-resistant Staphylococcus aureus and drug resistant strains of Streptococcus pneumoniae. The treatment approach to paediatric endocarditis is similar to that for adult patients with endocarditis because of similarities in disease pathogenesis and aetiology. The therapeutic goal is to achieve sterilisation of the cardiac vegetations. The choice of antibacterial is dependent upon the susceptibility profile of the causative organism. Vancomycin or gentamicin is recommended for enterococcal endocarditis, according to guidelines from the American Heart Association. For staphylococcal endocarditis in patients with no prosthetic valve, oxacillin or nafcillin with or without gentamicin is the treatment of choice. In the case of endocarditis caused by methicillin-resistant S. aureus, vancomycin is commonly used in patients with no prosthetic valve and a combination of vancomycin, gentamicin and rifampicin (rifampin) for patients with prosthetic material. Cefazolin or ceftriaxone is the treatment of choice for penicillin allergic paediatric patients with endocarditis caused by viridans streptococci. While there have been no major changes in endocarditis therapy for the last decade, the current focus is on the recognition of multiple-drug resistant pathogens and the use of newer agents such as quinupristin/dalfopristin in the treatment of resistant bacterial endocarditis. Prophylactic antibacterial therapy is recommended for procedures thought to be associated with the occurrence of bacteraemia involving organisms commonly associated with endocarditis. These include dental extractions and oral, respiratory tract, genitourinary, gastrointestinal or oesophageal procedures. Prophylactic antibacterials recommended by the American Heart Association during genitourinary and gastrointestinal surgical procedures in high risk patients include ampicillin + gentamicin or vancomycin + gentamicin in high risk patients with penicillin allergy. Ampicillin has been recommended for prophylaxis of bacterial endocarditis in children undergoing oral, respiratory tract or oesophageal procedures. In the case of penicillin allergy in these patients, cephalosporins, clindamycin, azithromycin or clarithromycin have been recommended. The general consensus is that antibacterial prophylaxis during dental procedure is unnecessary, and in fact propagates bacterial resistance.

Clostridial Enterocolitis

Equine clostridial enterocolitis is being recognized with increasing frequency. It has been identified in foals with diarrhea, antibiotic-associated enterocolitis, or nosocomial enterocolitis. The sporadic occurrence of clostridial enterocolitis, the variety of types of clostridia involved, and the difficulty of experimentally reproducing the disease suggest that it is a poorly defined multifactorial syndrome. The risk factors associated with susceptibility to colonization and progressive infection are largely based on anecdotal observations and extrapolation from human studies. Quantitative studies are needed to decipher the complex interactions between host and indigenous microflora that provide for and maintain a healthy colonization resistance environment. It seems that such studies might be more beneficial in furthering our understanding of the pathogenesis of clostridial enterocolitis than attempting to implicate another agent or toxin as the sole cause of the disease in equids. Treatment protocols that interrupt the pathogenesis of the disease need to be devised and critically evaluated to complement the present protocols emphasizing supportive care. Perhaps it is time to consider clostridial enterocolitis as yet another consequence of the use of antimicrobials analogous to the selective pressures that result in the emergence of multiple drug-resistant pathogens.

Etiology of Diarrhoea with Reference to Multiple Drug Resistant Enteric Bacterial Pathogens

A total of 340 stool samples were processed and studied from both sexes including all ages of patients. Association of enteropathogens between male and female was not statistically significant. Incidence of diarrhoea (28.23%) as well as prevalence of enteropathogens (34.31%) was found highest in the age group (20-30) years. The highest prevalence of enteropathogens (44.87%) was found in August. Of the total isolated enteropathogens, Vibrio cholerae O1 was observed in 51.96% followed by Shigella (18.6%) and Salmonella (8.82%) and parasites were also detected from 20.58% samples. All isolated V. cholerae O1 were El Tor, Inaba. Among Shigella, majority of isolates were S. flexneri. Among Salmonella, S. typhi, S. typhimurium and Salmonella spp. (polyvalent A-S positive) were identified. Entamoeba histolytica, Girdia lamblia, Ascaris lumbricoides and Trichuris trichiura were isolated among parasites. All isolated (100%) V. cholerae O1 were resistant to nalidixic acid and cotrimoxazole, whereas 68%; 63%; 53%; 37% and 11% Shigella were resistant to nalidixic acid, ampicillin, cotrimoxazol, mecillinam and ciprofloxacin respectively. Similarly, 55.5%; 44.4% and 11.1% Salmonella were resistant to nalidixic acid; ampicillin and cotrimoxazole respectively. All V. cholerae strains, 10 strains of Shigella and 2 strains of Salmonella were found multi drug resistant (MDR). The clinical history of the positive cases revealed that abdominal pain, fever, vomiting, dehydration and nausea were the symptoms of enteric infection. Key words: antibiotics; isolates; enteropathogen; Inaba DOI: 10.3126/njst.v9i0.3176 Nepal Journal of Science and Technology 9 (2008) 131-138