Aims and background: Broth microdilution (BMD) test is the preferred method for colistin susceptibility testing. However, Vitek (bioMérieux, USA) is commonly used because of user ease and cost considerations. Although previous studies have shown different agreement and error rates of the Vitek in comparison to BMD, there is a dearth of data regarding genus- and species-specific differences in error and agreement rates. This is important since such data may be the starting point of future research. Materials and methods: In this observational study, 705 isolates were studied [Klebsiella pneumoniae (n = 254), Escherichia coli (n = 275), Enterobacter cloacae (n = 20), Citrobacter spp. (n = 10), Acinetobacter spp. (n = 51), Pseudomonas aeruginosa (n = 92)]. Cluster- and convenience-based sampling methods were used. The study was conducted between November 2022 and February 2023. The BMD test was performed using Thermo Scientific reagents and the Sensititre Vizion Digital minimum inhibitory concentration (MIC) Viewing System. Antibiotic susceptibility testing (AST) by the Vitek-2 Compact system was performed using reagent AST-N281 cards. Results: Overall, 93.9% and 94.75% of isolates were intermediate to colistin by BMD and Vitek, respectively. Essential agreement (EA) and categorical agreement (CA) of Vitek and BMD were 88.09 and 97.73%, respectively. Very major error (VME) of Vitek was 23.81% (10/42), while major error (ME) was 0.76% (5/662). A high correlation (r > 0.7) in MIC values was observed between BMD and Vitek for Klebsiella pneumoniae and Citrobacter spp., while a moderate correlation (0.3 < r < 0.7) was observed for other species (Pearson correlation). Conclusion: This is one of the few studies from India that demonstrates the error rates of Vitek for a specific genus (e.g., Klebsiella spp., VME: 7.69%) to be significantly different from those of all organisms combined (VME: 23.81%). Although the overall EA of Vitek was 88.23%, the EA for Klebsiella spp. was only 73.93%. Genus- and species-dependent differences were observed with regard to MIC correlations between the two methods. Clinical significance: While testing, reporting, and interpreting colistin susceptibility for clinical management actions, it is important to understand the specific limitations of susceptibility test systems.

Introduction: Acinetobacter species are common in nature and can be isolated in noninfectious form from soil and freshwater samples, as well as in infectious or carrier stages from humans and animals. Because of its ease of survival and capacity to form biofilms on various implants and in the environment while being resistant to numerous antimicrobials, Acinetobacter is a highly effective opportunistic pathogen in healthcare environments. Acinetobacter species play a noteworthy role in healthcare-acquired infections. The bacteria have become successful hospital pathogens due to their multidrug resistance and ability to form biofilms, posing challenges to clinicians and microbiologists for management. Knowledge about the biofilm formation of Acinetobacter species, including the status of antimicrobial resistance, is crucial for optimizing therapy and infection control. Methods: This investigation comprised a variety of clinical samples required for bacterial culture and sensitivity testing in the clinical laboratory of the Department of Microbiology. Isolation, identification of microorganisms to the species level, antimicrobial susceptibility, and standard microbiological techniques were used for the detection of biofilm-producing Acinetobacter species. Results: A total of 500 isolates of Acinetobacter species were found from various clinical samples. Of these, 255 (51%) were identified as Acinetobacter calcoaceticus-baumannii complex (Acb complex), and 49% were identified as non-Acb complex by phenotypic methods. Biofilm production was detected in 185 (37%) isolates by the microtiter plate method. Biofilm formation on Congo red agar was observed in 12%, whereas 52% of strains were biofilm producers detected by the tube adherence method. The major species forming biofilms were from the Acb complex (77%). Additionally, 60% of the species were multidrug-resistant (MDR) with the capacity to create biofilms. Biofilm formers showed greater resistance to imipenem (66%). Conclusion: Acinetobacter is a nosocomial pathogen. Over the past 2 decades, Acinetobacter has emerged worldwide as a significant pathogen causing serious and sometimes fatal infections. The ability of this pathogen to infect hosts, form biofilms on medical devices, and acquire resistance to antibiotics is a significant concern for infectious disease specialists. Increased antimicrobial resistance has effectively limited many treatment options, raising concerns about the best therapeutic regimens. Improved surveillance for this organism is necessary at unit-specific, institutional, and national levels.

Monkeypox (mpox) is a viral infection of zoonotic origin caused by the mpox virus (MPXV), which is an Orthopoxvirus. Until 2021, mpox cases were mostly confined to endemic regions of Central Africa and West Africa, with sporadic cases in nonendemic areas linked to travel to endemic regions or following animal exposure. The global 2022 outbreak (caused by a new lineage B.1, clade 2b virus) was identified in May 2022 across many countries worldwide, with the first mpox case reported from Europe. As of 31 October 2024, over 126 countries reported more than 1,15,000 laboratory-confirmed cases of mpox, including 255 deaths. While previous outbreaks showed limited interhuman transmission and could be controlled, the 2022 outbreak showed rapid person-to-person transmission, mainly affecting bisexual men and male homosexuals. During this outbreak, the virus probably spread through close contact and sexual contact, with most patients having no prior animal exposure or travel to endemic regions. The clinical presentation of mpox cases during the 2022 outbreak was atypical, with lesions seen predominantly in the anogenital regions as opposed to the typical mpox rash. The preferred test to confirm mpox diagnosis is by detection of viral DNA by real-time or conventional polymerase chain reaction (PCR) test from cutaneous lesion samples. There is no specific approved treatment for mpox. Management of mild infections mainly involves supportive care. Patients with severe infections or complications should be hospitalized for management, and antiviral agents such as tecovirimat, cidofovir, or brincidofovir can be administered. Smallpox vaccines (JYNNEOS or ACAM2000) provide cross-protection against mpox and should be considered for prophylaxis, especially in healthcare workers and for other contacts of mpox cases. In this review, we discuss the virology, epidemiology, pathogenesis, clinical manifestations, treatment, and vaccination of mpox due to growing concern of the MPXV.

Following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, several countries, especially India, showed an alarming increase in coronavirus disease (COVID)-associated mucormycosis (CAM) cases, particularly in those with dysglycemia and the use of corticosteroids. Disseminated mucormycosis can affect all organs, but isolated involvement of the thyroid gland is extremely rare. Here, we describe a case of isolated mucormycosis of the thyroid gland in a 70-year-old woman with uncontrolled diabetes mellitus who had recovered from severe SARS-CoV-2 infection. The thyroid gland is immune to infections because of its high vascularity, high iodine content, and capsule. Fungal infections of the thyroid gland are very rare. To the best of our knowledge, this is the first case of post-COVID-19-associated mucormycosis of the thyroid gland reported in the literature.

Streptococcus agalactiae, a beta-hemolytic group B streptococcus (GBS) that causes neonatal meningitis and sepsis, is very rarely reported in infective endocarditis (IE). Here, we report a case of late prosthetic aortic valve IE caused by S. agalactiae, which was misidentified as Pediococcus pentosaceus in the VITEK 2 identification system. The identification was confirmed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and Sanger's sequencing. The probable cause of the misidentification is discussed. The patient was started on appropriate therapy based on antimicrobial susceptibility testing. At 3 months of follow-up, he was afebrile with normal prosthetic valve function.