A study of biofilm production and antimicrobial susceptibility pattern among urinary isolates

Urinary tract infection (UTI) is the most commonly acquired bacterial infection. Bacterial biofilms play an important role in urinary tract infections and are responsible for persistent infections as well as higher antimicrobial resistance. The microbial biofilms pose a public health problem as the microorganisms in the biofilms are difficult to treat with antimicrobial agents. So the present study was undertaken with the aim to study biofilm production and antimicrobial susceptibility pattern of urinary isolates. Aerobic bacterial isolates from urine samples submitted to microbiology laboratory for culture were included in the study. The isolates were tested for biofilm formation by Congo red agar method and Christensen tube method. Antimicrobial susceptibility tests were performed on these isolates by Kirby Bauer disk diffusion method as per CLSI guidelines. A total of 293 Gram negative bacilli and 59 Gram positive cocci were tested for biofilm production and antimicrobial susceptibility testing. : Gram‑negative organisms were predominant (83.24%) of all the isolates. Biofilm production was detected in 47% of the isolates. 51.7%), were the most common biofilm producing Gram negative bacilli followed by (44.32%). Amongst Gram positive cocci, (77.8%) was the most common biofilm producing organism. Biofilm producing urinary isolates displayed relatively less percentage of antimicrobial susceptibility than biofilm non producers. Biofilm forming isolates showed higher antimicrobial resistance as compared to biofilm non producer. Early detection of biofilm production in urinary isolates may aid clinicians in treatment of urinary tract infections.

Infective endocarditis caused by Enterobacteriaceae: phenotypic and molecular characterization of Escherichia coli and Klebsiella pneumoniae in Rio de Janeiro, Brazil

The etiological agent for infective endocarditis (IE), a life-threatening disease, is usually gram-positive bacteria. However, gram-negative bacteria can rarely cause IE and 4% of cases are associated with morbidity and mortality. This study aimed to characterize Escherichia coli and Klebsiella pneumoniae isolates from the blood of patients with IE. The characteristics of blood isolates were compared with those of urinary isolates from patients with urinary tract infections (UTIs). The results of this study revealed that K. pneumoniae isolates from patients with IE were phylogenetically related to those from patients with UTI. Additionally, the resistance phenotype, resistance gene, virulence gene, and plasmid profiles were similar between the blood and urinary isolates. The isolates belonging to the sequence types (STs) 76, 36, 101 (K. pneumoniae), and 69 (E. coli) are reported to be associated with drug resistance. The Enterobacteriaceae isolates from patients with IE did not produce extended-spectrum β-lactamase or carbapenemase. Additionally, this study investigated the virulence phenotype, biofilm formation ability, and the ability to adhere to the epithelial cells in vitro of the isolates. The isolates from patients with IE exhibited weaker biofilm formation ability than the urinary isolates. All isolates from patients with IE could adhere to the renal epithelial cells. However, three isolates from patients with UTIs could not adhere to the epithelial cells. The closely related K. pneumoniae isolates (648, KP1, KP2, KP3, and KP4) could not form biofilms or adhere to the epithelial cells. In summary, the molecular analysis revealed that the genetic characteristics of IE-causing K. pneumoniae and E. coli were similar to those of UTI-causing isolates. These isolates belonged to the STs that are considered treatable. Genetically similar isolates did not exhibit the same virulence phenotype. Thus, these non-hypervirulent clones must be monitored as they can cause complex infections in susceptible hosts.

Phenyl-lactic acid is an active ingredientin bactericidal supernatants of Lactobacillus crispatus

Lactobacillus crispatus is a well-established probiotic, with antimicrobial activity against pathogens across several niches of the human body generally attributed to the production of bacteriostatic molecules, including hydrogen peroxide and lactic acid. Here, we show that the cell-free supernatants of clinical isolates of L. crispatus harbor robust bactericidal activity. We further identify phenyl-lactic acid as a bactericidal compound with properties and susceptibility range near-identical to that of the cell-free supernatant. As such, we hypothesize that phenyl-lactic acid is a key active ingredient in L. crispatus supernatant. IMPORTANCE Although Lactobacillus crispatus is an established commensal microbe frequently used in probiotics, its protective role in the bladder microbiome has not been clarified. We report here that some urinary isolates of L. crispatus exhibit bactericidal activity, primarily due to its ability to excrete phenyl-lactic acid into its environment. Both cell free supernatants of L. crispatus isolates and phenyl-lactic acid exhibit bactericidal activity against a wide range of pathogens, including several that are resistant to multiple antibiotics.

Nitrofurantoin Susceptibility Pattern in Gram-Negative Urinary Isolates: In Need of Increased Vigilance

Nitrofurantoin is the first-line drug in the treatment of uncomplicated urinary tract infections (UTIs) and its use has increased exponentially in recent years. Objectives This study aims to determine the susceptibility pattern of nitrofurantoin in gram-negative urinary isolates and to evaluate their bacteriological and epidemiological profile along with co-existing resistance to other important urinary antimicrobials. Material and Methods This was a retrospective study conducted in a tertiary care hospital in New Delhi in which 500 gram-negative bacterial urinary isolates were evaluated. Records of antimicrobial susceptibility were reviewed from July to September 2019. Antimicrobial susceptibility was performed using the Kirby–Bauer disk diffusion method on Mueller Hinton agar and interpreted using CLSI 2019. Test for extended spectrum β-lactamase (ESBL) producers was done using double disk approximation test. Statistical Analysis Data analysis was performed using the SPSS windows version 25.0 software. Results Out of total 500 isolates, 20.17% (94) isolates were resistant (R) to nitrofurantoin and 9.01% (42) were found to be intermediate (I). Highest resistance was seen in Klebsiella sp. (44.61%) and Escherichia coli (8.12%). About 28.82% of the I/R isolates were of the pediatrics age group and most of the isolates belonged to females (64.69%). High resistance was also seen against ampicillin (92.30%), cefazolin (88.46%), ceftazidime (73.0%), and fluoroquinolones (65.38%). Carbapenemase co-resistance was seen in 57.15% isolates whereas ESBL production was seen in 30.76% of E. coli and 12.06% of Klebsiella sp. Conclusion Increase in multidrug resistance uropathogens along with a near absence of novel oral antibiotics has led to increased consumption of nitrofurantoin since its resistance has increased.

Reintroduction of nitrofurantoin in the treatment of uncomplicated urinary tract infection

The present study was designed to reintroduce an older antimicrobial nitrofurantoin among a group of prescribers and to explore the relationship between the reintroduction and corresponding shift in sensitivity pattern of the microbes. The microbial sensitivity against ciprofloxacin before intervention was 46.6%, which significantly increased after intervention (51.8%). Treatment with nitrofurantoin resulted in a total clinical cure rate of 80.6%, of which rate of clinical cure achieved in expected time was 66.1% and delayed was 14.5%. The rate of total clinical cure with nitrofurantoin corresponded closely with the proportion of urinary isolates sensitive to nitrofurantoin. i.e., 86.3%. This preliminary study revealed that revival might be an effective strategy to increase the sensitivity and to delay the emergence of resistance.