What are common Gram-positive bacilli in the urine?

From the Guidelines

Common gram-positive bacilli found in urine include Corynebacterium species, Lactobacillus species, Gardnerella vaginalis, Actinomyces species, and Bacillus species. These organisms are often considered contaminants when isolated from urine cultures, as they typically represent normal flora from the skin, vagina, or urethra rather than true urinary tract infections. However, in certain clinical contexts—such as immunocompromised patients, those with indwelling catheters, or after urologic procedures—these bacteria can cause genuine infections. Corynebacterium urealyticum is particularly noteworthy as it can cause alkaline-encrusted cystitis and is associated with urinary stones due to its urease activity 1. Lactobacillus is commonly found in female urine samples due to vaginal colonization. When evaluating the significance of these gram-positive bacilli in urine, clinicians should consider the bacterial count (typically >10^5 CFU/mL suggests infection), presence of pyuria, patient symptoms, and whether the sample was properly collected to minimize contamination. Some key points to consider when managing these infections include:

• The most common causes of bacteremia, including gram-positive bacilli, are listed in Table 2 of the 2002 guidelines for the use of antimicrobial agents in neutropenic patients with cancer 1.
• The diagnosis of asymptomatic bacteriuria should be based on results of culture of a urine specimen collected in a manner that minimizes contamination 1.
• Treatment, when necessary, typically involves antibiotics like vancomycin, linezolid, or daptomycin for resistant strains, though susceptibility testing should guide therapy. It's also important to note that the provided evidence does not directly address the question of common gram-positive bacilli in urine, but rather provides information on the diagnosis and treatment of urinary tract infections and asymptomatic bacteriuria. However, based on the available information, the most appropriate course of action is to consider the clinical context and evaluate the significance of gram-positive bacilli in urine based on bacterial count, presence of pyuria, patient symptoms, and proper sample collection.

From the Research

Common Gram-Positive Bacilli in Urine

• Gram-positive bacilli that can be found in urine include:
  • Actinomyces species, such as Actinomyces neuii 2
  • Corynebacterium species, such as Corynebacterium aurimucosum and Corynebacterium kroppenstedtii 2
  • Lactobacillus species, which are commonly found in the urinary tract, particularly in women 3
• These bacteria can cause urinary tract infections (UTIs), particularly in individuals with risk factors such as being elderly, pregnant, or having other underlying medical conditions 4
• Some gram-positive bacilli, such as Lactobacillus, can be beneficial and help prevent UTIs, while others can be pathogenic and cause infection 3, 5
• Accurate identification of gram-positive bacilli in urine is essential to determine whether an isolate is clinically significant or a contaminant 2