Comparison of Colistin Susceptibility via Two Different Methods in Gram-Negative Extensive Drug-Resistance Isolates from ICU Patients.

OBJECTIVE: To compare the susceptibility of colistin by two methods in extensive drug-resistant (XDR) Gram-negative isolates from ICU patients. STUDY DESIGN: Cross-sectional comparative analysis. Place and Duration of the Study: Department of Microbiology, Combined Military Hospital Karachi, Pakistan, from August 2022 to February 2023. METHODOLOGY: A total of 100 clinical specimens received from the intensive care unit yielded growth of extensively drug-resistant gram-negative bacteria, which were evaluated for polymyxin E susceptibility. The agar dilution method was compared with the reference broth microdilution (BMD) method. Minimum inhibitory concentration (MIC) was noted for both methods. RESULTS: Comparison of the MIC method by agar dilution showed a 90% correlation with the reference method of broth microdilution. With MICs within the acceptable range of the clinical and laboratory standards institute (CLSI) recommendations, 89 isolates were susceptible to colistin, whereas only 11 remained resistant. Polymyxin E's MIC 50 and MIC 90 were determined to be 1 and 2 µg/ml, respectively, with 97% susceptibility. CONCLUSION: Agar dilution susceptibility method can be used for screening purposes for the susceptibility testing of polymyxin E. This method is reliable and can easily identify the heteroresistance. KEY WORDS: Extensively drug-resistant, Broth microdilution, Multidrug-resistant, Agar dilution, Minimum inhibitory concentration, Colony forming unit.

Management of Chronic Osteomyelitis and Antibiotic Stewardship; An Effort to Delay the Post-Antibiotic Era.

OBJECTIVE: To develop an effective antimicrobial strategy for the management of chronic osteomyelitis. STUDY DESIGN: Observational study. Place and Duration of the Study: Departments of Microbiology and Orthopaedics, Combined Military Hospital Malir, Karachi, Pakistan, from January 2021 to February 2022. METHODOLOGY: Bone biopsies of 45 enrolled participants were taken for microbiological evaluation. Intravenous antibiotic therapy was begun as per empirical therapy based on the local antibiogram and antibiotic policy. Once the susceptibility pattern was available, targeted therapy started and continued for 28 to 42 days. Patients were evaluated based on inflammatory markers and clinical conditions for a minimum of six months to a maximum of one year. RESULTS:  Out of the 45 patients, the majority 29% were soldiers, 40% belonging to the age group of 31-60 years. The common predisposing factor was trauma/fractures followed by diabetes and implants leading to chronic sinus discharge and decubitus ulcers. The most commonly isolated organism was Staphylococcus aureus (38%) followed by Methicillin-resistant Staphylococcus aureus (MRSA) (31%). Cotrimoxazole and Rifampicin turned out to be good treatment options. Only 4.4% showed unsatisfactory prognosis, nonetheless, no mortality was observed during the course of treatment. CONCLUSION: In this study, highly resistant strains were observed with limited treatment options for chronic osteomyelitis, however, effective stewardship programmes with accurate diagnostic reporting and judicious use of antimicrobials can prevent overuse of the valuable resources. KEY WORDS: Antimicrobial stewardship, Osteomyelitis, Methicillin-resistant Staphylococcus aureus, Empirical therapy, Antimicrobial resistance.

Health care associated Clostridioides difficile infection and colonization in patients admitted at tertiary care hospital Pakistan.

Objectives: To evaluate the epidemiology of clostridioides difficile infections and colonisation in a tertiary-care setting. METHODS: The cross-sectional study was conducted at the Combined Military Hospital, Rawalpindi, Pakistan, from June 1, 2017, to October 31, 2019, and comprised adult patients admitted in high-risk units of the hospital for any disease experiencing watery stools after 48 hours of hospital admission and passing more than 3 stools per day with no other recognised aetiology. Stool samples of the participants, diagnosed with antibiotic associated diarrhoea, were submitted for glutamate dehydrogenase antigen assay and clostridioides toxin A/B assay detected by enzyme-linked immunosorbent assay and clostridioides difficile toxin gene detection by polymerase chain reaction. Clostridium difficile-associated diarrhoea was diagnosed by a positive toxin assay or polymerase chain reaction. Data was analysed using SPSS25. RESULTS: Of the 715 subjects, 322(45%) were males and 393(55%) were females. The overall mean age was 56.64±8.57 years, and 488(68.3%) were aged <60 years, while 227(31.7%) were aged >60 years. The incidence of clostridioides difficile-associated diarrhoea was found in 10(1.4%) patients and was highest in oncology unit 3(4.3%). No positive case was detected from the high dependency unit and the surgical ward. All the10(1.4%) positive cases were on >2 antibiotics with a combination of oral vancomycin and intravenous metronidazole. Mortality rate was significantly higher in the positive cases compared to those with clostridioides difficile colonisation (p<0.05). CONCLUSIONS: The incidence of clostridioides difficile-associated diarrhoea was found to be low.

Catheter related recurrent blood stream infection caused by linezolid-resistant, methicillin resistant Staphylococcus haemolyticus; an emerging super bug.

A 61 year male, admitted in Combined Military Hospital Rawlpindi on 12th March 2017, operated for diverticulitis became colonized with Staphylococcus haemolyticus. Patient suffered repeated septic episodes caused by the same organism during his stay in hospital. The strain was identified as methicillin resistant Staphylococcus haemolyticus (MRSH) also resistant to Linezolid by analytical profile index for Staphylococcus (API Staph) and VITEK 2 Gram positive cocci panel. The isolate was cultured from blood cultures, Central Venous Catheter (CVC) tip and skin swabs. Patient was successfully treated with injectable vancomycin and skin decolonization was acheived with chlorhexidine bath after which no episode of MRSH infection occurred. Patient had an uneventful recovery and was discharged on 21st June. His follow up visit showed clinical improvement.

Native valve dual pathogen endocarditis caused by Burkholderia cepacia and Aspergillus flavus - a case report.

INTRODUCTION: Infective endocarditis (IE) is an important clinical condition with significant morbidity and mortality among the affected population. A single etiological agent is identifiable in more than 90 % of the cases, however, polymicrobial endocarditis (PE) is a rare find, with a poor clinical outcome. Here we report a case of native valve dual pathogen endocarditis caused by Burkholderia cepacia and Aspergillus flavus in an immunocompetent individual. It is among unique occurrences of simultaneous bacterial and fungal etiology in IE. CASE PRESENTATION: A 30-year-old male was admitted to a cardiology institute with complaints of low grade intermittent fever and progressive shortness of breath for last two months. He was a known case of rheumatic heart disease and had suffered an episode of IE three years ago. On the basis of clinical presentation and the results of radiological investigations, a diagnosis of infective endocarditis was made. Paired blood samples for culture and sensitivity, sampled before the commencement of antimicrobial therapy, yielded growth of Burkholderia cepacia which was highly drug resistant. Sensitivity results-directed therapy consisting of tablet Trimethoprim-Sulfamethoxazole, two double-strength tablets 12 hourly, and Meropenem, 1 g IV every 8 h, was commenced. Despite mild relief of fever intensity, overall clinical condition did not improve and double valve replacement therapy was carried out. Excised valves were sent for microbiological analysis. Burkholderia cepacia was grown on tissue culture with a similar antibiogram to that previously reported from the blood culture of this patient. Direct microscopy of section of valvular tissue with 10 % KOH revealed abundant fungal hyphae. Patient serum galactomannan antigen assay was also positive. Histopathological examination of vegetations also revealed hyphae typical of species of the genus Aspergillus. The patient was successfully treated with meropenem, trimethoprim-sulfamethoxazole and voriconazole. CONCLUSION: The hallmark of successful treatment in this case was exact identification of pathogens, antibiogram-directed therapy and good liaison between laboratory experts and treating clinicians.

Cerebral Abscess caused by Novel Species: Streptococcus Pluranimalium.

Streptococcus pluranimalium, a gram-positive aerobic coccus, has been isolated primarily from several farm animals. The pathogenicity of this species is not well characterised either in animals or humans. As per the literature, cases of S. pluranimalium infection in humans have been reported only a handful of times. We report the case of cerebral abscess caused by S. pluranimalium in a patient who presented with weakness and confusion. The diagnosis of cerebral abscess was made on imaging supported by microbiological culture. Burr hole procedure for abscess drainage followed by an antibiotic regimen based on culture and sensitivity results contributed to a successful outcome. The bacteria were identified by analytical profile index for Streptococci (API Strep) and VITEK 2 gram-positive cocci panel. The case was successfully treated with vancomycin.

Bacterial biofilm-based catheter-associated urinary tract infections: Causative pathogens and antibiotic resistance.

BACKGROUND: We sought to determine the incidence of bacterial biofilm-based catheter-associated urinary tract infections, identify variables affecting biofilm formation, and identify etiologic bacterial pathogens and antibiotic-resistance patterns associated with biofilm-based catheter-associated urinary tract infections (CAUTIs) in our setup. METHODS: Patients who developed at least 2 symptoms of urinary tract infection after at least 2 days of indwelling urinary catheters were included. Urine was collected aseptically from catheter tubing and processed per standard microbiologic practices. Bacterial pathogens were identified on the basis of gram staining, colony morphology, and biochemical reactions. The detection of the biofilm was done using the tube adherence method. Drug susceptibility testing was done using the Kirby-Bauer disc diffusion method. FINDINGS: Biofilm was detected in 73.4% isolates, whereas 26.6% of isolates were nonbiofilm producers. Mean duration of catheterization after which biofilm was detected was 5.01 ± 1.31 days. A latex catheter was used in 69.5% of patients, whereas a silicone catheter was used in 30.4% of patients. Escherichia coli was found to be the most common pathogen isolated (52.3%), whereas Enterobacter cloacae exhibited the highest biofilm production (87.5%) among isolated pathogens. Among biofilm producers, the highest resistance was observed with ampicillin (100%). Fosfomycin exhibited the lowest resistance (17.2%). Significant association with biofilm was detected for gender, duration of catheterization, and type of catheter. CONCLUSION: Biofilm-based CAUTI is an emerging problem. E coli was the most frequent isolate. High antibiotic resistance was observed in biofilm-producing strains. Using the variables affecting biofilm formation, tailored intervention strategies can be implemented to reduce biofilm-based CAUTIs.