Acute Hematogenous Osteomyelitis of the Pelvis in Children

BACKGROUND

Pelvic involvement has been reported in 3%-14% of acute hematogenous osteomyelitis (AHO) cases in children. One guideline suggests need for a longer antibiotic course in pelvic AHO, however, recent data are lacking. We describe the clinical course of children with pelvic AHO and compare it to nonpelvic AHO.

METHODS

A retrospective review of patients with a diagnosis of AHO admitted to Texas Children's Hospital from January 2012 to December 2020 was conducted. Patients 6 months-<19 years old and with ≤14 days of symptoms at admission were eligible. Patients with sickle cell disease or immunocompromised were excluded. Wilcoxon rank-sum test assessed for differences between continuous variables and Fisher exact for categorical variables using STATA 17.

RESULTS

We compared 104 cases of pelvic AHO to 314 cases of nonpelvic AHO. Patients had similar microbiology, length of stay and length of antibiotic therapy. Patients with pelvic AHO had pyomyositis identified by magnetic resonance imaging more often (28.8 vs. 9.4%, P < 0.001) and bone abscess less often (22.1 vs. 46.5%, P < 0.001). Rates of chronic complications were comparable between patients with pelvic AHO and nonpelvic AHO (8.4% vs. 15.1%, P = 0.1). Nineteen patients (18.3%) with pelvic AHO received ≤30 antibiotic days without complications, but they had less need for intensive care or bone abscesses than patients treated longer.

CONCLUSIONS

Pelvic AHO in children may be more frequent than previously reported but is not associated with more complications. Four weeks of therapy may be sufficient in selected patients. Prospective studies to compare outcomes with different lengths of therapy are needed.

Assessing Risk for Complications in Acute Hematogenous Osteomyelitis in Children: Validation of 2 Predictive Scores

BACKGROUND

Acute hematogenous osteomyelitis (AHO) can be associated with severe complications which can be difficult to predict in the clinical setting. The previously published predictive acute complication score ("A-SCORE") and chronic complication score ("C-SCORE") show promise, however, further external validation is needed.

METHODS

We performed a retrospective study of 418 children with AHO and analyzed the performance of A-SCORE (variables included bone abscess, fever after 48 h of starting antibiotics, suppurative arthritis, disseminated disease, and delayed source control) to predict risk for acute complicated course (treatment failure, prolonged admission, and/or need for ≥2 bone debridements) and C-SCORE (includes disseminated disease, bone debridement, and CRP ≥10 mg/dL at 2-4 days after starting antibiotics) to predict chronic complications (growth restriction, pathologic fracture, chronic osteomyelitis, avascular necrosis, joint deformity, and/or frozen joint).

RESULTS

An acute complicated course occurred in 106/418 (25.4%); 51/380 (13.5%) with complete follow-up data had a chronic complication. The A-SCORE performed with similar specificity (78%) and negative predictive value (NPV) (92%), and higher sensitivity (81%) and increased area under the receiver operating curve (AUC) (0.87) in our population. The C-SCORE performed with similar sensitivity (64%) and NPV (94%) but had lower specificity (86%) and AUC (0.71) than originally reported. Other variables associated with development of complications such as tibia involvement and bacteremia ≥2 days were identified but did not result in significantly improved predictive scores.

CONCLUSIONS

Predictive A-SCORE and C-SCORE for AHO complications in children may help guide acute management and long-term follow-up decisions. Prospective studies are needed to determine their applicability.

Development and validation of a multiplex real-time PCR assay for detection and quantification of Streptococcus pneumoniae in pediatric respiratory samples

IMPORTANCE

Streptococcus pneumoniae (Spn) is the world's leading cause of lower respiratory tract infection morbidity and mortality in children. However, current clinical microbiological methods have disadvantages. Spn can be difficult to grow in laboratory conditions if a patient is pre-treated, and Spn antigen testing has unclear clinical utility in children. Syndromic panel testing is less cost-effective than targeted PCR if clinical suspicion is high for a single pathogen. Also, such testing entails a full, expensive validation for each panel target if used for multiple respiratory sources. Therefore, better diagnostic modalities are needed. Our study validates a multiplex PCR assay with three genomic targets for semi-quantitative and quantitative Spn molecular detection from lower respiratory sources for clinical testing and from upper respiratory sources for research investigation.

Decrease in Pediatric Invasive Pneumococcal Disease During the COVID-19 Pandemic

Measures to limit SARS-CoV-2 transmission in 2020 reduced other viral infections. Among 7 US children's hospitals, invasive pneumococcal disease cumulative incidence decreased by 46% in 2020 vs 2017-2019. Limited droplet transmission of pneumococci and preceding viral pathogens may be responsible.

Clinical and Microbiologic Variables Predictive of Orthopedic Complications Following Staphylococcus aureus Acute Hematogenous Osteoarticular Infections in Children

BACKGROUND

Staphylococcus aureus is the most common cause of acute hematogenous osteoarticular infections (AHOAIs) in children. The risk factors for the development of orthopedic complications (OC) after AHOAI are poorly understood. We sought to describe clinical and microbiologic variables present on the index admission that may predict OC in S. aureus AHOAI.

METHODS

Staphylococcus aureus AHOAI cases were identified from 2011-2017 at Texas Children's Hospital and reviewed for the development of OC. OC included chronic osteomyelitis, growth arrest, avascular necrosis, chronic dislocation, and pathologic fracture. All S. aureus isolates were characterized by pulsed-field gel electrophoresis and agr group.

RESULTS

A total of 286 cases were examined of which 27 patients (9.4%) developed OC. Patients who developed OC more often had infection with an agr group III organism (P = .04), bacteremia (P = .04), delayed source control (P < .001), ≥2 surgical procedures (P < .001), intensive care unit admission (P = .09), and fever >4 days after admission (P = .008). There was no association with OC and patient age, methicillin resistance, or choice/route of antibiotics. In multivariable analyses of OC, infection with agr group III S. aureus, prolonged fever, and delayed source control remained statistically significant.

CONCLUSIONS

OC develop following S. aureus AHOAI in 9.4% of cases. Although the development of OC is likely multifactorial, agr group III organisms, prolonged fever, and delayed source control are independently associated with OC. Moreover, early aggressive surgical source control may be beneficial in children with S. aureus AHOAI.

Invasive Pneumococcal Disease in Infants Aged 0-60 Days in the United States in the 13-Valent Pneumococcal Conjugate Vaccine Era

We identified 53 infants aged 0-60 days with invasive pneumococcal disease (IPD) at 8 children's hospitals in the United States (2005-2015). After the introduction of 13-valent pneumococcal conjugate vaccine (PCV13), IPD caused by PCV13 serotypes decreased ~30% providing some evidence of indirect protection. However, approximately 60% of IPD was still caused by PCV13 serotypes.

Invasive pneumococcal infections in children following transplantation in the pneumococcal conjugate vaccine era

BACKGROUND

Pediatric recipients of hematopoietic stem cell and solid organ transplants are at increased risk of invasive pneumococcal infections (IPI). Data on IPI in this population are scarce. To our knowledge, this is the first study describing the epidemiology of IPI among pediatric transplant recipients in the pneumococcal conjugate vaccine (PCV) era.

METHODS

We identified transplant recipients with IPI at 8 children's hospitals in the U.S. from our surveillance database (2000-2014). Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory. Categorical variables were analyzed by Fisher's exact test and continuous variables with nonparametric tests. Indirect cohort study design was used to calculate vaccine effectiveness.

RESULTS

We identified 65 episodes of IPI in transplant recipients. Recurrent IPI was observed in 10% of transplant recipients. The IPI crude incidence rate in solid organ transplant recipients was higher than in the general population. Most IPI episodes occurred >6 months after transplantation. Bacteremia and pneumonia were the most common presentations. Meningitis was unusual. No case fatalities were observed. Serotype 19A was the most common serotype (n=10), followed by 6C (n=7). In 2010-2014, 37% of IPI was caused by PCV13 serotypes. Four cases of vaccine breakthrough were identified. Most isolates were susceptible to penicillin and ceftriaxone. Pneumococcal conjugate and polysaccharide immunization rates were low.

CONCLUSION

Pediatric transplant recipients remain at increased risk of IPI in the vaccine era. Most cases presented as a late post-transplant infection. The interval between transplantation and IPI may allow adequate time for pneumococcal immunization.

Role of Operative or Interventional Radiology-Guided Cultures for Osteomyelitis

BACKGROUND AND OBJECTIVE

Acute hematogenous osteomyelitis (AHO) is a severe infection in children. Drainage of purulent collections in bones provides specimens for culture as well as therapeutic benefit. Interventional radiology (IR)-guided procedures may serve as a less invasive means of culture in select patients. We examined the impact of IR and surgically obtained cultures in the diagnosis and management of AHO.

METHODS

A retrospective review of cases of AHO was performed from 2011 to 2014. Patients with chronic disease, orthopedic hardware, puncture wounds, or an infected contiguous focus were excluded.

RESULTS

A total of 250 cases met inclusion criteria. Blood cultures were positive in 107 of 231 cases (46.3%), and 123 of 150 patients had positive cultures (82%) obtained by orthopedic surgery. Of these 123 patients, 62 (50.4%) had organisms identified only through operating room (OR) cultures. Of the 66 patients who had cultures obtained by IR, 34 (51.5%) had positive IR cultures. For those with positive IR cultures, 18 (52.9%) had negative blood cultures. Among the 80 patients with negative blood culture and positive OR/IR culture, the results changed antibiotic therapy in 68 (85%) patients.

CONCLUSIONS

IR or OR culture was the only means of identifying a pathogen in 80 of 216 cases (37%), and in >80% changed medical management. IR can be used effectively to obtain bone cultures in children with AHO not requiring open surgical drainage. Further research is needed to better understand the optimal utilization of IR and OR culture in pediatric AHO.

Impact of the 13-Valent Pneumococcal Conjugate Vaccine on Pneumococcal Meningitis in US Children

BACKGROUND

The impact of 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal meningitis (PM) in US children is unknown. We compared the serotype distribution, antibiotic susceptibility, hospital course, and outcomes of children with PM 3 years before and 3 years after the introduction of PCV13.

METHODS

We identified patients ≤ 18 years of age with PM at 8 children's hospitals in the United States. Pneumococcal isolates were collected prospectively. Serotyping and antibiotic susceptibility were performed in a central laboratory. Clinical data were abstracted from medical records. Patients were divided into 3 subgroups: pre-PCV13 (2007-2009), transitional year (2010), and post-PCV13 (2011-2013). Categorical variables were analyzed by the χ(2) test and continuous variables by the Mann--Whitney U test.

RESULTS

During the study period, 173 of 1207 episodes (14%) of invasive pneumococcal disease were identified as PM; 76 of 645 (12%) were during 2007-2009 and 69 of 394 (18%) during 2011-2013 (50% increase; P = .03). The proportion of PCV13 serotype cases decreased from 54% in 2007-2009 to 27% in 2011-2013 (P = .001). Non-PCV13 serotype cases represented 73% of the isolates in 2011-2013. Isolates with ceftriaxone minimum inhibitory concentration ≥ 1 µg/mL decreased (13% to 3%) from 2007-2009 to 2011-2013 (P = .03). No significant differences were identified for hospital course or outcome, with the exception that a greater proportion of patients had subdural empyema and hemiparesis in 2011-2013.

CONCLUSIONS

After the introduction of PCV13, the number of cases of PM in children remained unchanged compared with 2007-2009, although the proportion of PCV13 serotypes decreased significantly. Serotype 19A continued to be the most common serotype in 2011-2013. Antibiotic resistance decreased significantly. Morbidity and case-fatality rate due to PM remain substantial.

Staphylococcus aureus infections among children receiving a solid organ transplant: clinical features, epidemiology, and antimicrobial susceptibility

BACKGROUND

Staphylococcus aureus is among the most common causes of healthcare-associated infection (HAI) in the United States. Patients who have received a solid organ transplant (SOT) represent a unique population for the acquisition of HAIs, given their preoperative organ failure, immunosuppression, and need for invasive procedures. However, limited literature is published on S. aureus infections among children with SOT. We describe the epidemiology, antimicrobial susceptibility, and clinical features of S. aureus infections among pediatric SOT recipients.

DESIGN

An ongoing prospective S. aureus surveillance database from 2001 to 2012 was searched for infections in patients with a history of SOT at Texas Children's Hospital. Medical records and antibiotic susceptibility profiles were reviewed; specific attention was applied to the time since transplantation to infection.

RESULTS

Out of the total of 696 transplants performed during the study period, 38 pediatric SOT recipients developed 41 S. aureus infections; the highest incidence of infection was among heart recipients. Overall, the most common infectious diagnoses were skin-and-soft-tissue infections (66.1%), followed by bacteremia (15.3%). Among isolates in SOT patients, 47.5%, 16.9%, and 6.7% were resistant to methicillin, clindamycin, or mupirocin, respectively. Three infections (7.3%) occurred in the early post-transplant period (<1 month), all of which were bacteremia (P = 0.007) and all caused by methicillin-susceptible S. aureus (MSSA). The majority of infections (90.2%) occurred in the late post-transplant period (>6 months). In 10 cases (16.9%), S. aureus infection was associated with graft rejection during the same admission.

CONCLUSIONS

S. aureus represents an important cause of morbidity in pediatric SOT recipients. While the majority of infections occurred late after transplant (>6 months), those acquired in the early post-transplant period were more often invasive and caused by MSSA in our hospital. Physicians caring for SOT recipients should be aware of the risks posed by this pathogen and the potential concomitant morbidity including graft rejection.

Staphylococcus aureus sinus infections in children

OBJECTIVE

Staphylococcus aureus can cause sinusitis in children. The predominant MRSA clone in the United States, USA300, has been associated with skin and soft tissue as well as invasive diseases. USA300 has increased among CA methicillin-susceptible S. aureus (CA-MSSA) isolates. We describe the clinical characteristics of pediatric patients with S. aureus cultured from sinus specimens, treated at Texas Children's Hospital (TCH), and characterized their isolates by molecular methods.

METHODS

This was a retrospective study of children with endoscopic sinus surgery (ESS) cultures positive for S. aureus between 01/2005 and 12/2008 at TCH. Medical records were reviewed and associated S. aureus isolates were characterized by pulsed field gel electrophoresis (PFGE). Data were analyzed by Mann-Whitney U, Chi-square, Fisher's exact test, and Chi-square for trend.

RESULTS

We identified 56 patients with S. aureus sinus infections; 12 (21%) were MRSA. Seven of 12 (58%) MRSA vs. 5/44 (11%) MSSA were USA300 (p<0.01). All MRSA isolates were non-susceptible to erythromycin compared to 30% of MSSA (p<0.01); 75% of the USA300 strains were non-susceptible to erythromycin compared to 36% of the non-USA300 strains (p<0.04). Co-pathogens were isolated from 77% (43/56) of the patient specimens. Both MRSA and USA300 isolates were associated with Haemophilus influenzae co-isolation (p<0.05). Patients with USA300 strains were significantly younger (p=0.02) and more likely to experience snoring as a symptom associated with their sinusitis (p=0.03) than those infected with non-USA300 strains. Children with MRSA (4/12) tended to have a greater recurrence rate than children with MSSA isolates (5/44) (p=0.09). No significant differences were observed between groups for fever or complications such as neck cellulitis, nasal abscess, meningitis, subdural empyema, and orbital cellulitis.

CONCLUSION

MSSA was more commonly isolated than MRSA from sinus cultures of children who underwent ESS at TCH. The majority of ESS cultures positive for S. aureus, were mixed with other respiratory pathogens, principally H. influenzae. USA300 was the major clone among the MRSA sinusitis isolates, but was not associated with more complications than other S. aureus isolates.

Hospital-acquired Staphylococcus aureus infections at Texas Children's Hospital, 2001-2007

OBJECTIVE

To document the introduction of the methicillin-resistant Staphylococcus aureus (MRSA) USA300 clone into a children's hospital. Current molecular epidemiology of infections due to the USA300 strain of MRSA in the pediatric healthcare setting remains obscure.

DESIGN

Retrospective study of patients with hospital-acquired S. aureus infection during the period from August 1, 2001, through July 31, 2007, at Texas Children's Hospital in Houston.

METHODS

Patients with hospital-acquired S. aureus infection from whom an isolate was available for molecular analysis were included. Clinical information was obtained from patient medical records and the electronic hospital information system. S. aureus isolates underwent antimicrobial susceptibility testing, pulsed-field gel electrophoresis, and polymerase chain reaction testing for staphylococcal cassette chromosome (SCC) mec, agr, the diamine N-acetyltransferase gene, and the Panton-Valentine leukocidin genes (pvl).

RESULTS

Of 242 patients with hospital-acquired S. aureus infection, 147 (61%) had methicillin-susceptible S. aureus infection. Of the 95 MRSA isolates causing hospital-acquired infection, 69 (73%) were USA300 isolates, and that rate did not increase over time. Skin and soft tissue infection (P < .001), onset of infection less than 10 days after admission (P = .007), and lack of comorbidities (P < .001) were associated with hospital-acquired MRSA infection caused by the USA300 strain, compared with other isolates (hereafter referred to as non-USA300 isolates). Nine of 10 patients with a S. aureus infection at the time of death were infected with a non-USA300 strain. USA300 carried SCCmec IV, agr I, the diamine N-acetyl transferase gene, and pvl. USA300 isolates were more susceptible to clindamycin, gentamicin, and trimethoprim-sulfamethoxazole than were other non-USA300 isolates (P < .01).

CONCLUSIONS

In our patient population, the annual numbers of observed cases of hospital-acquired S. aureus infection have remained constant. USA300 was the most common clone and, compared with other non-USA300 MRSA isolates, was associated with skin and soft tissue infection, early onset of infection after admission, and greater susceptibility to antimicrobial agents.

Subtle genetic changes enhance virulence of methicillin resistant and sensitive Staphylococcus aureus

Background

Community acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) increasingly causes disease worldwide. USA300 has emerged as the predominant clone causing superficial and invasive infections in children and adults in the USA. Epidemiological studies suggest that USA300 is more virulent than other CA-MRSA. The genetic determinants that render virulence and dominance to USA300 remain unclear.

Results

We sequenced the genomes of two pediatric USA300 isolates: one CA-MRSA and one CA-methicillin susceptible (MSSA), isolated at Texas Children's Hospital in Houston. DNA sequencing was performed by Sanger dideoxy whole genome shotgun (WGS) and 454 Life Sciences pyrosequencing strategies. The sequence of the USA300 MRSA strain was rigorously annotated. In USA300-MRSA 2658 chromosomal open reading frames were predicted and 3.1 and 27 kilobase (kb) plasmids were identified. USA300-MSSA contained a 20 kb plasmid with some homology to the 27 kb plasmid found in USA300-MRSA. Two regions found in US300-MRSA were absent in USA300-MSSA. One of these carried the arginine deiminase operon that appears to have been acquired from S. epidermidis. The USA300 sequence was aligned with other sequenced S. aureus genomes and regions unique to USA300 MRSA were identified.

Conclusion

USA300-MRSA is highly similar to other MRSA strains based on whole genome alignments and gene content, indicating that the differences in pathogenesis are due to subtle changes rather than to large-scale acquisition of virulence factor genes. The USA300 Houston isolate differs from another sequenced USA300 strain isolate, derived from a patient in San Francisco, in plasmid content and a number of sequence polymorphisms. Such differences will provide new insights into the evolution of pathogens.

Three-year surveillance of community onset health care-associated staphylococcus aureus infections in children

BACKGROUND

Staphylococcus aureus causes skin and soft tissue or invasive infections in children in the community, in the hospital or in other ways associated with the health care system (HCA).

METHODS

Prospective community-acquired S. aureus infection surveillance at Texas Children's Hospital was initiated on August 1, 2001. Community onset HCA (CO HCA) infections were identified. Demographic and clinical data were collected. Antibiotic susceptibilities were determined. Data were analyzed by chi or Student's t test. CO HCO-isolates were characterized by pulsed field gel electrophoresis and staphylococcal chromosomal cassette carrying the mecA methicillin-resistant gene (SCCmec) typing.

RESULTS

From August 1, 2001 to July 31, 2004, 61.5% of 322 in year 1, 62.9% of 259 in year 2 and 56.9% of 318 in year 3 of CO HCA isolates were methicillin-resistant S. aureus (MRSA). Among the CO HCA-MRSA isolates, 8.9% of 542 were from children with invasive infections compared with 24.1% of 357 CO HCA-methicillin-susceptible S. aureus (MSSA; P < 0.001). Sixty-six percent of children with CO HCA-S. aureus isolates were admitted to the hospital. Clindamycin resistance increased over the 3 years (CO HCA-MRSA, from 3.5% to 18.8%, P < 0.001; CO HCA-MSSA, from 3.2% to 10.2%, P = 0.053). Thirty-three of 35 (94.3%) CO HCA-MRSA carried SCCmecIV; 30 were USA300. Only 3 of 35 MSSA were related to USA300 by pulsed field gel electrophoresis.

CONCLUSIONS

CO HCA-S. aureus infections remained steady over the 3-year study at Texas Children's Hospital. Clindamycin resistance increased >4-fold for CO HCA-S. aureus isolates over the 3 years and is no longer appropriate for empiric treatment of invasive infections suspected to be caused by CO HCA-MRSA at our hospital. In our setting, CO HCA-MRSA infections are steady in number despite substantial increases in community-acquired MRSA infections and both being related to the same clone.