Lack of clinical utility of urine gram stain for suspected urinary tract infection in pediatric patients

Clinical usefulness of urine Gram stain for diagnosing urinary tract infections at the emergency department

BACKGROUND

Diagnosis of urinary tract infections (UTIs) is a frequent challenge at the emergency department (ED). The clinical usefulness of the urine Gram stain (GS) is uncertain.

OBJECTIVE

We studied the GS performance to clarify its clinical utility at the ED.

METHODS

Urine dipstick (UD), automated urinalysis (UF-1000i), GS and urine culture (UC) were performed in a cohort of consecutive adults presenting at the ED suspected of a UTI. GS performance was assessed and compared to UD and UF-1000i.

RESULTS

A UTI diagnosis was established in 487/1358 (35.9%) episodes. Sensitivity and specificity for 'many' GS leucocytes was 33.7% and 95.4%; for 'many' GS bacteria 51.3% and 91.0%. GS diagnostic performance by ROC analysis was 0.796 for leucocytes and 0.823 for bacteria. GS bacteria performed better than UD nitrite comparable to UF-1000i bacteria. GS leucocytes underperformed compared to UD leucocyte esterase and UF-1000i leucocytes. UC was positive in 455 episodes. GS correctly predicted urine culture of gram-negative rods (PPV 84.6%). Prediction was poor for gram-positive bacteria (PPV 38.4% (cocci), 1.0% (rods)).

CONCLUSION

With the exception of a moderate prediction of gram-negative bacteria in the UC, urine GS does not improve UTI diagnosis at the ED compared to other urine parameters.

Role of urine Gram stain in young febrile infants with a suspected urinary tract infection: a cohort study

OBJECTIVE

To analyse the performance of the urine Gram stain for predicting a positive urine culture (UC) in young infants with fever without source (FWS) and pyuria.

DESIGN

Observational study; secondary analysis of a prospective registry-based cohort study.

SETTING

Paediatric emergency department; tertiary teaching hospital.

PATIENTS

Infants ≤90 days old with FWS, pyuria and urine Gram stain requested seen between 2010 and 2022.

MAIN OUTCOME MEASURE

Performance of the Gram stain, defined as positive if any bacteria were seen, for predicting urinary tract infection (UTI: UC by urethral catheterisation growing >10 000 CFU/mL of a single bacterial pathogen).

RESULTS

Among 367 febrile infants with pyuria, 281 (76.6%) had a positive Gram stain and 306 (83.3%) had a positive UC (277; 90.5% Escherichia coli).Rates of positive UC in patients with positive and negative Gram stains were 97.2% and 38.4%, respectively (p<0.01), showing a sensitivity of 89.2% (95% CI: 85.2% to 92.2%) and a specificity of 86.9% (95% CI: 76.2% to 93.2%). Sensitivity was lower for diagnosing UTIs caused by bacteria other than E. coli (69.0% vs 91.3% for UTIs caused by E. coli; p<0.01).Two (2.1%) of the 86 infants with negative Gram stains were diagnosed with bacteraemia unrelated to a UTI (Streptococcus pneumoniae and Staphylococcus aureus).

CONCLUSIONS

Around a third of infants with pyuria and a negative Gram stain will eventually be diagnosed with a UTI. These patients have a higher rate of UTIs caused by bacteria other than E. coli. Bacterial infections other than UTIs should also be considered in such cases.

Actinotignum schaalii Can Be an Uropathogen of "Culture-Negative" Febrile Urinary Tract Infections in Children with Urinary Tract Abnormalities

Accurate diagnosis and treatment of febrile urinary tract infections (UTI) during childhood are important for the prevention of renal parenchymal damage and functional loss, and detection of underlying diseases related to chronic kidney disease (CKD). Actinotignum schaalii (A. schaalii)-related febrile UTI in children is rare, and its incidence and risk factors remain unclear. A 3-year-old boy with a history of UTI presented with fever and vomiting. Although the culture of his urine specimen in air was negative, A. schaalii was observed in a 5% carbon dioxide (CO₂) culture condition, as well as an anaerobic one. A diagnosis of febrile UTI was made, and he recovered with antibiotic therapy. He was found to have CKD associated with vesicoureteral reflux (VUR) after further investigations. A. schaalii is one of the causative agents of febrile UTI in children with urinary tract abnormalities. Although the culture in the air could show negative results, urine culture in 5% CO₂ and anaerobic conditions is useful for diagnosis. Our case is the youngest and the first known case of A. schaalii-related febrile UTI associated with VUR in children.

Teleclinical Microbiology: An Innovative Approach to Providing Web-Enabled Diagnostic Laboratory Services in Syria

OBJECTIVES

Telemedicine can compensate for the lack of health care specialists in response to protracted humanitarian crises. We sought to assess the usability of a teleclinical microbiology (TCM) program to provide diagnostic services in a hard-to-reach region of Syria.

METHODS

A semimobile station was equipped with conventional micrograph and macrograph digital imaging systems. An electronic platform (Telemicrobiology in Humanitarian Crises, TmHC) was created to facilitate sharing, interpreting, and storing the results. A pilot study was conducted to identify the bacterial species and antimicrobial susceptibility pattern of 74 urinary clinical isolates. An experience survey was conducted to capture the feedback of 8 participants in the program.

RESULTS

The TmHC platform (https://sdh.ngo/tmhc/) enabled systematic transmission of the laboratory records and co-interpretation of the results. The isolates were identified as Escherichia coli (n = 61), Klebsiella pneumoniae (n = 12), and Proteus mirabilis(n = 1). All the isolates were multidrug resistant. The performance of our TCM module was rated 4 (satisfying) and 5 (very satisfying) by 6 and 2 users, respectively. Data security of and cost-effectiveness were the main perceived concerns.

CONCLUSIONS

Although we encountered several context-related obstacles, our TCM program managed to reach a highly vulnerable population of 4 million people confined in the northwest region of Syria.

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

Background

Febrile urinary tract infections (fUTIs), which include pyelonephritis, prostatitis, and urosepsis, are the most common cause of sepsis. However, the treatment has become more complex because of the worldwide increase in antimicrobial resistance (AMR). The objective of this study was to clarify whether point-of-care Gram stain (PCGS) of urine contributed to fUTI diagnosis and treatment in adults.

Methods

This hospital-based observational study was undertaken between January 2013 and March 2015 in Okinawa, Japan. All enrolled patients were adults who had been admitted to the Division of Infectious Diseases with suspected fUTI. The usefulness of PCGS results were compared for urinalysis (U/A) and urine cultures (U/Cs). The targeted therapy type and its susceptibility based on PCGS were analyzed, and each was investigated in two groups: the uncomplicated pyelonephritis group and the complicated pyelonephritis/prostatitis group.

Results

Two hundred and sixty-six patients were enrolled. The results of PCGS were closely correlated with those of U/A for pyuria and bacteriuria, and moderately correlated with the results of U/C for bacterial types. In the uncomplicated group, narrow-spectrum antimicrobials such as cefotiam were initially selected in 97.9% (47/48) of patients, and their susceptibility was 97.9% (47/48). In the complicated group, the susceptibility was 84.2% (186/221) (p = 0.009) despite frequent AMRs (14.7%; 32/218) and low use of broad-spectrum antimicrobials such as carbapenems (7.7%; 17/221).

Conclusion

Urine PCGS led to a more precise fUTI diagnosis and prompted clinicians to select narrower-spectrum antibiotics with high susceptibility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07194-9.

Diagnostic value of biomarkers for paediatric urinary tract infections in primary care: systematic review and meta-analysis

Background

Accurate diagnosis of urinary tract infection is essential as children left untreated may suffer permanent renal injury.

Aim

To compare the diagnostic values of biomarkers or clinical prediction rules for urinary tract infections in children presenting to ambulatory care.

Design and setting

Systematic review and meta-analysis of ambulatory care studies.

Methods

Medline, Embase, WOS, CINAHL, Cochrane library, HTA and DARE were searched until 21 May 2021. We included diagnostic studies on urine or blood biomarkers for cystitis or pyelonephritis in children below 18 years of age. We calculated sensitivity, specificity and likelihood ratios. Data were pooled using a bivariate random effects model and a Hierarchical Summary Receiver Operating Characteristic analysis.

Results

Seventy-five moderate to high quality studies were included in this review and 54 articles in the meta-analyses. The area under the receiver-operating-characteristics curve to diagnose cystitis was 0.75 (95%CI 0.62 to 0.83, n = 9) for C-reactive protein, 0.71 (95% CI 0.62 to 0.80, n = 4) for procalcitonin, 0.93 (95% CI 0.91 to 0.96, n = 22) for the dipstick test (nitrite or leukocyte esterase ≥trace), 0.94 (95% CI 0.58 to 0.98, n = 9) for urine white blood cells and 0.98 (95% CI 0.92 to 0.99, n = 12) for Gram-stained bacteria. For pyelonephritis, C-reactive protein < 20 mg/l had LR- of 0.10 (95%CI 0.04–0.30) to 0.22 (95%CI 0.09–0.54) in children with signs suggestive of urinary tract infection.

Conclusions

Clinical prediction rules including the dipstick test biomarkers can support family physicians while awaiting urine culture results. CRP and PCT have low accuracy for cystitis, but might be useful for pyelonephritis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12875-021-01530-9.

Performance of the Modified Boston and Philadelphia Criteria for Invasive Bacterial Infections

BACKGROUND

The ability of the decades-old Boston and Philadelphia criteria to accurately identify infants at low risk for serious bacterial infections has not been recently reevaluated.

METHODS

We assembled a multicenter cohort of infants 29 to 60 days of age who had cerebrospinal fluid (CSF) and blood cultures obtained. We report the performance of the modified Boston criteria (peripheral white blood cell count [WBC] ≥20 000 cells per mm³, CSF WBC ≥10 cells per mm³, and urinalysis with >10 WBC per high-power field or positive urine dip result) and modified Philadelphia criteria (peripheral WBC ≥15 000 cells per mm³, CSF WBC ≥8 cells per mm³, positive CSF Gram-stain result, and urinalysis with >10 WBC per high-power field or positive urine dip result) for the identification of invasive bacterial infections (IBIs). We defined IBI as bacterial meningitis (growth of pathogenic bacteria from CSF culture) or bacteremia (growth from blood culture).

RESULTS

We applied the modified Boston criteria to 8344 infants and the modified Philadelphia criteria to 8131 infants. The modified Boston criteria identified 133 of the 212 infants with IBI (sensitivity 62.7% [95% confidence interval (CI) 55.9% to 69.3%] and specificity 59.2% [95% CI 58.1% to 60.2%]), and the modified Philadelphia criteria identified 157 of the 219 infants with IBI (sensitivity 71.7% [95% CI 65.2% to 77.6%] and specificity 46.1% [95% CI 45.0% to 47.2%]). The modified Boston and Philadelphia criteria misclassified 17 of 53 (32.1%) and 13 of 56 (23.3%) infants with bacterial meningitis, respectively.

CONCLUSIONS

The modified Boston and Philadelphia criteria misclassified a substantial number of infants 29 to 60 days old with IBI, including those with bacterial meningitis.

The Role of Gram-Negative Bacteria in Urinary Tract Infections: Current Concepts and Therapeutic Options

Urinary tract infections (UTIs) are some of the most common infections in human medicine worldwide, recognized as an important public health concern to healthcare systems around the globe. In addition, urine specimens are one of the most frequently submitted samples for culture to the clinical microbiology laboratory, exceeding the number of most of the other sample types. The epidemiology, species-distribution and susceptibility-patterns of uropathogens vary greatly in a geographical and time-dependent manner and it also strongly correlated with the reported patient population studied. Nevertheless, many studies highlight the fact that the etiological agents in UTIs have changed considerably, both in nosocomial and community settings, with a shift towards "less common" microorganisms having more pronounced roles. There is increasing demand for further research to advance diagnostics and treatment options, and to improve care of the patients. The aim of this review paper was to summarize current developments in the global burden of UTI, the diagnostic aspects of these infectious pathologies, the possible etiological agents and their virulence determinants (with a special focus on the members of the Enterobacterales order), current guidelines and quality indicators in the therapy of UTIs and the emergence of multidrug resistance in urinary pathogens.

Utility of point-of-care Gram stain by physicians for urinary tract infection in children ≤36 months

Urinary tract infection (UTI) in children requires early diagnosis and treatment to prevent repeated UTI and renal scarring. This study aimed to evaluate the usefulness of the point-of-care Gram stain by physicians for suspected UTI in children at Okinawa Chubu Hospital as a rapid diagnostic test.A single-center, retrospective study was undertaken between January 2011 and December 2015. Patients aged 36 months or younger who were reviewed had suspected UTI in the emergency room or outpatient clinic. Urine culture, urinalysis, and point-of-care Gram stain were performed on a single specimen. Patients with structural or functional urological defects requiring routine catheterization were excluded. We compared the diagnostic performance among the rapid diagnostic tests (i.e., pyuria, point-of-care Gram stain, or both). Kappa statistics were used to evaluate the agreement between the results of point-of-care Gram stain and morphotypes of urine culture with the 95% CI (bias corrected bootstrap interval). We also analyzed which antibiotics were more susceptible to the bacteria of urine culture results, selected by the results of point-of-care Gram stain or empirical treatment based on the Japanese guidelines by McNemar test.Of 1594 patients reviewed in the study, 1546 were eligible according to our inclusion criteria. Using urine culture as the gold standard for UTI, the sensitivity and specificity of pyuria were 73.2% and 95.1%, whereas those of the point-of-care Gram stain were 81.4% and 98.2%, respectively. The concordance rate between the morphotypes of bacteria detected by point-of-care Gram stain and those of urine culture was 0.784 (kappa coefficient) (95% CI 0.736-0.831). Furthermore, the proportion of "susceptible" in the minimum inhibitory concentration of pathogen-targeted treatment based on the point-of-care Gram stain was higher than that of empirical therapy (exact McNemar significance probability: .0001).Our analysis suggests that the point-of-care Gram stain is a useful rapid diagnostic tool for suspected UTI in young children. Pathogen-targeted treatment based on the point-of-care Gram stain would lead to better antibiotic selection compared with empirical therapy.

Direct Gram staining and its various benefits in the diagnosis of bacterial infections

In the era of rapid development of molecular and other diagnostic methods, direct Gram staining (DGS) tends to remain in the background, although it can provide both microbiologists and clinicians numerous benefits. The aim of this review was to emphasize the importance of DGS for the diagnosis of many clinically important infections. A PubMed search was carried out using relevant keywords for articles published primarily since 2010. The DGS can provide early information for a timely diagnosis of infections, can reveal the causative agents of the infections even under suboptimal conditions of specimen collection, transport or identification methods, can detect the presence of rare/unusual pathogens, moreover, the method shows the specimen quality, by distinguishing between contamination and true infection, it can direct or change initial antibiotic treatment before the availability of culture results, can indicate the need of other methods for pathogen identification and, in some cases, can show the need for emergency attention such as urgent antibiotic therapy and surgical measures. Briefly, the DGS remains an easy, rapid, inexpensive and important method, which use should be encouraged in conditions of a standardized and controlled performance to avoid technical or interpretation errors.

Diagnosis of Urinary Tract Infections in Children

Urinary tract infections (UTIs) are a common occurrence in children. The management and laboratory diagnosis of these infections pose unique challenges that are not encountered in adults. Important factors, such as specimen collection, urinalysis interpretation, culture thresholds, and antimicrobial susceptibility testing, require special consideration in children and will be discussed in detail in the following review.