Point-of-care urine Gram stain led to narrower-spectrum antimicrobial selection for febrile urinary tract infection in adolescents and adults

Reviving Sternheimer stain: A single-center retrospective study to detect the diagnostic utility of urinary tract infections in the emergency department

INTRODUCTION

Qualitative urinalysis using the Sternheimer stain is a common method in Japan for identifying bacteriuria, but there is a lack of studies examining its test characteristics. In this study, we aimed to investigate the sensitivity and specificity of the Sternheimer stain for urine culture results and compare it with the sensitivity and specificity of the Gram stain. Our goal was to determine the usefulness of the Sternheimer stain in identifying bacteriuria.

PATIENTS AND METHODS

Among 986 patients aged 16 years or older from whom samples for both urinalysis and urine culture were obtained at the emergency room of Tenri Hospital from January 2019 to December 2019, 342 patients with pyuria, defined as the presence of 10 or more white cells per cubic millimeter in a urine specimen, who had not received prior antimicrobial therapy were included. Urine cultures were used for comparison to determine the sensitivity and specificity of Sternheimer and Gram stain in this patient group. A positive Sternheimer stain result was defined as bacteriuria ≥ (1+), and that of Gram stain was defined as ≥ 1/1 field of high-power ( × 1000) oil immersion.

RESULTS

Using urine culture results for comparison, the sensitivity of Sternheimer stain was 92.2%, the specificity was 48.5%, the positive likelihood ratio was 1.79, and the negative likelihood ratio was 0.16.

DISCUSSION

Sternheimer stain is a rapid and useful method to exclude bacteriuria in a group of patients with pyuria in the emergency department.

Diagnostic Accuracy of Point-of-Care Gram Stains in Obstructive Pyelonephritis due to Ureteral Stones

Background

The diagnostic utility of point-of-care (POC) Gram stains for obstructive pyelonephritis with hydronephrosis is not well established. The current study aimed to assess the diagnostic accuracy of urine Gram stains in patients with obstructive pyelonephritis due to ureteral stones.

Methods

A retrospective observational study was conducted on patients with obstructive pyelonephritis admitted to our hospital between January 2011 and December 2021. The diagnostic accuracy of Gram stains was evaluated based on the severity of hydronephrosis, including Gram stains performed by both trained physicians and microbiological technicians.

Results

After analyzing 210 patients, POC Gram stains of bladder urine presented a sensitivity, specificity, positive predictive value, and negative predictive value of 86.8%, 81.8%, 93.7%, and 66.7%, respectively, for gram-negative rods and 65.7%, 83.4%, 48.9%, and 91.0%, respectively, for gram-positive cocci. The agreement between POC Gram stains and urine culture was good for gram-negative rods, with a kappa (κ) coefficient of 0.637 and agreement rate of 85.6%, and moderate for gram-positive cocci, with a κ coefficient of 0.435 and agreement rate of 80%. The agreement between POC Gram stains and bladder urine culture results for gram-negative rods was higher in the mild hydronephrosis group (κ coefficient = 0.677) than in the severe hydronephrosis group (κ coefficient = 0.466). Discrepancies in Gram stain results between physicians and technicians were observed in 21 of 180 cases (11.7%).

Conclusions

POC Gram stains for gram-negative rods may be a useful diagnostic tool for obstructive pyelonephritis, particularly in cases of mild hydronephrosis.

Occult Bacteremia Caused by Enterococcus-Associated Pyuria in an Elderly Man

We report a case of Enterococcus-associated pyelonephritis in a 74-year-old Parkinson's patient. He showed constipation, a mild fever, and altered consciousness. Blood cultures revealed Gram-positive cocci (GPC), prompting vancomycin treatment. Urinary Gram staining confirmed pyelonephritis, underscoring its diagnostic utility in elderly patients with vague symptoms. Enterococcus faecalis infections can be insidious, with the potential for organ abscesses and persistent fever. Due to nuanced presentations of Gram-positive infections versus Gram-negative ones, diagnosis can be delayed, risking sepsis. Gram-staining urine is vital, especially in older patients, as untreated Gram-positive bacteremia elevates mortality. Given our aging population and their comorbidities, Gram staining's role in quick antibiotic administration is crucial. Hence, its integration into community hospitals is advocated. This case emphasizes early detection and treatment of GPC infections in the elderly and endorses Gram staining for prompt diagnosis of Enterococcus-associated pyelonephritis.

Is it meaningful to apply midstream urine culture to urine specimens with negative Gram stain results?

INTRODUCTION

Gram staining is a convenient method for bacterial estimation. Urine culture is typically used to diagnose urinary tract infections. Therefore, urine culture is also performed on Gram stain-negative urine specimens. However, the frequency of uropathogen identification in these samples remains unclear.

METHODS

From 2016 to 2019, we retrospectively compared the results of Gram staining and urine culture tests on midstream urine specimens submitted for the diagnosis of urinary tract infections to confirm the significance of urine culture on Gram stain-negative specimens. Analysis was performed according to the patients' sex and age, and the frequency of uropathogen identification in the culture was examined.

RESULTS

A total of 1763 urine specimens (women, 931; men, 832) were collected. Of these, 448 (25.4%) were not positive on Gram staining but were positive on culture. In specimens without bacteria on Gram staining, the frequencies of specimens with uropathogens detected on culture were 20.8% (22/160) in women aged <50 years, 21.4% (71/332) in women aged ≥50 years, 2.0% (2/97) in men aged <50 years, and 7.8% (39/499) in men aged ≥50 years.

CONCLUSIONS

In men aged <50 years, the frequency of uropathogenic bacteria identification by urine culture was low in Gram stain-negative specimens. Therefore, urine cultures may be excluded from this group. In contrast, in women, a small number of Gram stain-negative specimens showed significant culture results for the diagnosis of urinary tract infection. Therefore, urine culture should not be omitted in women without careful consideration.

Can Gram staining be a guiding tool for optimizing initial antimicrobial agents in bacterial infections?

The emergence of multidrug-resistant organisms poses a significant threat to global public health, making the optimization of antimicrobial use crucial. Antimicrobial therapy is often initiated in emergency rooms (ERs) and intensive care units (ICUs), where patients are at high risk of infection. Prompt antimicrobial selection is essential in these facilities, and point-of-care testing can guide the appropriate initial antimicrobial therapy. Gram staining, a quick and inexpensive method, was previously used for point-of-care testing by physicians in the 1980s but was discontinued in 1988 in the United States. However, in Japan, the clinical practice of Gram stain-based antimicrobial therapy by physicians has continued in a limited number of hospitals. Several studies undertaken in Japan have shown that Gram staining carried out by trained physicians can reduce the overuse of broad-spectrum antimicrobial agents in ERs and ICUs without worsening patients' outcomes. Gram stain-based antimicrobial therapy reduced unnecessary use of carbapenems in the ER. Furthermore, Gram staining has been shown to significantly reduce the overuse of broad-spectrum antimicrobials without worsening clinical cure and mortality for patients with ventilator-associated pneumonia in the ICU. The classic technique of Gram staining has regained its usefulness through persistent clinical practice in Japan. It is hoped that Japanese researchers in this field will demonstrate to the world the efficacy of the classic technique of Gram staining in addressing this critical problem. Gram staining carried out by trained physicians could serve as a valuable means of optimizing antimicrobial treatment in ERs and ICUs.

High yield of blood cultures in the etiologic diagnosis of cellulitis, erysipelas, and cutaneous abscess in elderly patients

Background

Cellulitis is a common disease in the elderly, and detecting etiologic organisms with blood cultures is difficult because of the low positive rate and occasional skin contamination. Therefore, routine blood cultures are not recommended for uncomplicated cellulitis. However, it is unclear whether blood culture collection for the diagnosis of cellulitis in elderly patients is useful.

Methods

This single hospital–based observational study was performed between April 2012 and March 2015 in Okinawa, Japan. All enrolled patients were aged 15 years or older and admitted to the Division of Infectious Diseases with suspected cellulitis, erysipelas, and cutaneous abscess. Two routine sets of blood cultures were obtained.

Results

Two hundred and twenty-one patients were enrolled. The median age was 77 years. The proportion of bacteremia was 21.7% for all patients (48/221), 8.5% (4/47) for those <65 years, and 25.3% (44/174) for those ≥65 years old (P = .013). The skin contamination rate was 0.9% (2/221). The most common pathogen was Streptococcus dysgalactiae (62.5%). Gram-negative bacteremia not susceptible to cefazolin was detected in 8.3%. Cefazolin and ampicillin were the first- and second-most commonly used therapies. Anti–methicillin-resistant Staphylococcus aureus therapy was required in 3.6% of patients. In addition to age and severe infection, shaking chills and white blood count ≥13 000 cells/µL were independent risk factors of bacteremia.

Conclusions

Two routine sets of blood cultures are recommended for the precise diagnosis and appropriate treatment of cellulitis in elderly patients, especially in patients with shaking chills or leukocytosis.