Clinically important Gram negative bacilli

• Dysuria is painful urination
• Frequency is the need to urinate more often than what is normal to you
• Suprapubic means above the pubic bone
• Flank tenderness is pain at the side of the torso just below the ribs
• Urolithiasis is the presence of stones in the urinary tract
• Pyelonephritis is a kidney infection
• MSU stands for midstream urine
• MALDI-TOF stands for Matrix-assisted laser desorption ionization–time of flight mass spectrometry
• ESBL stands for Extended spectrum beta lactamase
• Enterobacterales are a family of gram-negative bacilli that are common causes of intra-abdominal, urinary, respiratory tract, and bloodstream infections
• Enterobacterales are a large order of different types of bacteria that commonly cause infections in healthcare settings and communities
• Examples of germs in the Enterobacterales order include Escherichia coli (E. coli) and Klebsiella pneumoniae
• Normal intestinal flora in Enterobacterales include Escherichia coli, Klebsiella spp., Proteus spp., Serratia spp., Enterobacter spp., and Citrobacter spp.
• Pathogens in Enterobacterales include Salmonella spp., Shigella spp., Yersinia spp., and toxin-producing E.coli
• Enterobacterales are mostly motile with peritrichous flagella, except for Klebsiella which are non-motile
• E. coli is the most common causative organism in community and hospital urinary tract infections
• Laboratory diagnosis of Gram-negative bacilli involves growth on non-selective and selective media like MacConkey agar to differentiate lactose fermenters from non-lactose fermenters
• Further identification of Gram-negative bacilli involves biochemical testing or MALDI-TOF and antimicrobial susceptibility testing
• Treatment for E. coli infections depends on the isolate, with options like amoxicillin for community-acquired infections and piperacillin-tazobactam or cefuroxime for hospital-acquired infections
• Trends in E. coli invasive infections show a percentage of multi-drug resistance (MDR), defined as resistance to 3GCs, fluoroquinolones, and aminoglycosides
• In 2021, multi-drug resistance accounted for 4.1% of isolates, a decrease from 4.8% in 2020
• Proteus mirabilis infections are associated with complicated UTIs, urolithiasis, and catheter-associated urinary tract infections (CAUTIs)
• P. mirabilis uses swarming motility to migrate across the catheter surface in CAUTIs
• Urease production by P. mirabilis generates ammonia, elevates urine pH, and leads to calcium and magnesium crystallization, potentially causing urinary retention and infections
• Laboratory diagnosis of Proteus mirabilis includes a 'swarming' appearance on blood but not on MacConkey agar, where they form non-lactose fermenting colonies
• Treatment for Proteus mirabilis infections depends on the isolate and includes Beta-lactams, aminoglycosides, and co-trimoxazole, while being resistant to nitrofurantoin and tetracycline
• Klebsiella pneumoniae, a normal inhabitant of the GIT, is not associated with gastroenteritis/diarrhoeal disease but can cause healthcare-associated infections like VAP, UTI, intra-abdominal infections, and BSI
• Treatment for Klebsiella spp. infections includes Beta-lactams, quinolones, or aminoglycosides, depending on the isolate's susceptibility
• Klebsiella pneumoniae is often resistant to multiple antibiotics, including ESBL, and may cause healthcare-associated infections like VAP
• A report from the microbiology lab showing Klebsiella pneumoniae resistant to various antibiotics indicates likely involvement of extended-spectrum beta-lactamase (ESBL) production
• Pseudomonas aeruginosa, an environmental pathogen, causes a wide range of hospital-acquired infections and is intrinsically resistant to many antibiotics
• Treatment options for P. aeruginosa infections include piperacillin-tazobactam, ciprofloxacin, aminoglycosides, and carbapenems like meropenem