Increasing incidence of nontyphi Salmonella bacteremia among children living in southern Israel

Non-typhoidal Salmonella bacteremia: comparison of adults and children in a single medical center

Introduction. Non-typhoidal Salmonella (NTS) bacteremia can cause significant morbidity and mortality. There is high incidence of Salmonellosis in the Middle East, including Israel, but there is a paucity of data on the clinical and epidemiological features of children in comparison to adults.Hypothesis/Gap Statement. Previous studies describing the differences between paediatric and adult populations with Salmonella bacteremia are sparse.Aim. This study's aim was to describe the differences between adults and children with NTS bacteremia.Methodology. All records of patients with NTS bacteremia between 1 January 1998 and 31 July 2020 were reviewed. Data regarding clinical manifestations and laboratory results were extracted from the medical records; records of children (aged <18 years) were compared with those of adults.Results. Records for 137 cases of Salmonella bacteremia (69 adults and 68 children, aged 2 days to 98 years) were reviewed. Seventy nine (58 %) patients had concomitant gastrointestinal symptoms. Fifty-eight (84 %) adults and 13 (19 %) children had underlying conditions (P<0.001). Eighteen patients died, none of whom was a child. Over the study period, most of the children (n=46, 67 %) but only five adults were discharged from the emergency department on their first visit to the ED.Conclusions. The main characteristics of NTS bacteremia in children compared to adults, are higher rates of prior discharge from emergency department, higher rate of gastrointestinal symptoms and better prognosis.

Correlates of non-typhoidal Salmonella bacteraemia: A case-control study

OBJECTIVE

Limited up-to-date evidence exists on host-related characteristics of non-typhoidal Salmonella (NTS) bacteraemia in high-income countries. Correlates of NTS bacteraemia in Israel were examined in this study.

METHODS

A case-control study was conducted using the medical records of patients hospitalized with NTS bacteraemia in Jerusalem during 1997-2016 (n=106; 57 children, 49 adults). Two control groups were included: (1) randomly selected controls (n=101), who were patients hospitalized due to bacteraemia with other pathogens; (2) patients with salmonellosis without bacteraemia (n=112). Age-stratified logistic regression models were constructed.

RESULTS

In children, a recent emergency room visit was associated with an increased likelihood of NTS bacteraemia. In adults, the likelihood of NTS bacteraemia versus salmonellosis increased in relation to Charlson comorbidity score (adjusted odds ratio (aOR) 1.29, 95% confidence interval (CI) 1.00-1.66, for each 1-point increase in the score), while an inverse association was found with haemoglobin level (aOR 0.72, 95% CI 0.54-0.95). Steroid therapy increased the likelihood of NTS bacteraemia compared to patients with bacteraemia due to other pathogens (aOR 5.22, 95% CI 1.01-26.93).

CONCLUSIONS

In children, NTS bacteraemia was probably present at their prior emergency room visit. A high comorbidity burden increased the likelihood of bacteraemia in adults with Salmonella infection, while haemoglobin level might be protective.

Etiology of invasive bacterial infections in immunocompetent children in Korea (1996-2005): a retrospective multicenter study

The purpose of this study was to identify the major etiological agents responsible for invasive bacterial infections in immunocompetent Korean children. We retrospectively surveyed invasive bacterial infections in immunocompetent children caused by eight major pediatric bacteria, namely Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species that were diagnosed at 18 university hospitals from 1996 to 2005. A total of 768 cases were identified. S. agalactiae (48.1%) and S. aureus (37.2%) were the most common pathogens in infants younger than 3 months. S. agalactiae was a common cause of meningitis (73.0%), bacteremia without localization (34.0%), and arthritis (50%) in this age group. S. pneumoniae (45.3%) and H. influenzae (20.4%) were common in children aged 3 months to 5 yr. S. pneumoniae was a common cause of meningitis (41.6%), bacteremia without localization (40.0%), and bacteremic pneumonia (74.1%) in this age group. S. aureus (50.6%), Salmonella species (16.9%), and S. pneumoniae (16.3%) were common in older children. A significant decline in H. influenzae infections over the last 10 yr was noted. S. agalactiae, S. pneumoniae, and S. aureus are important pathogens responsible for invasive bacterial infections in Korean children.

Salmonella enterica bacteraemia: a multi-national population-based cohort study

Background

Salmonella enterica is an important emerging cause of invasive infections worldwide. However, population-based data are limited. The objective of this study was to define the occurrence of S. enterica bacteremia in a large international population and to evaluate temporal and regional differences.

Methods

We conducted population-based laboratory surveillance for all salmonella bacteremias in six regions (annual population at risk 7.7 million residents) in Finland, Australia, Denmark, and Canada during 2000-2007.

Results

A total of 622 cases were identified for an annual incidence of 1.02 per 100,000 population. The incidence of typhoidal (serotypes Typhi and Paratyphi) and non-typhoidal (other serotypes) disease was 0.21 and 0.81 per 100,000/year. There was major regional and moderate seasonal and year to year variability with an increased incidence observed in the latter years of the study related principally to increasing rates of non-typhoidal salmonella bacteremias. Advancing age and male gender were significant risk factors for acquiring non-typhoidal salmonella bacteremia. In contrast, typhoidal salmonella bacteremia showed a decreasing incidence with advancing age and no gender-related excess risk.

Conclusions

Salmonella enterica is an important emerging pathogen and regional determinants of risk merits further investigation.

Community-acquired bloodstream infections in children > one month old in southern Israel (1992–2001): Epidemiological, clinical and microbiological aspects

We studied the epidemiology, microbiology, clinical picture and outcome of community-acquired bloodstream infections (CABI) in children in southern Israel during 1992-2001. Information was collected prospectively by daily surveillance. CABI was diagnosed when a positive blood culture was reported in a patient discharged from the emergency room or during <48 h since admission if hospitalized. There were 1439 CABI episodes in 1396 children aged 1 month to 14 y. CABI incidence was 100/100,000 children with no increase during the study period. Risk of CABI was 3.8 times higher in a Bedouin than in a Jewish child. 1561 bacteria (793, 50%, gram-positive and 768, 49% gram-negative organisms, respectively) and 13 fungi were recovered. Most frequent gram-positive organisms were Streptococcus pneumoniae (509 isolates, 32% of all isolates, 64% of all gram-positive), Staphylococcus aureus (137, 9%, 17%) and Streptococcus pyogenes (46, 3%, 6%). Enterobacteriaceae spp. were the most frequent gram-negative pathogens (279, 18%, 36%), followed by Brucella (205, 13%, 27%). S. pneumoniae was the most common pathogen in children <12 months and 1-5 y age; Brucella was the most frequent pathogen in children >5 y of age. Coverage of 7-valent pneumococcal conjugated vaccine for CABI was 38.5%. 38 (2.7%) patients died; 16 cases were caused by S. pneumoniae.

Epidemiologic attributes of invasive non-typhoidal Salmonella infections in Michigan, 1995–2001

OBJECTIVES

To determine: (1) the incidence of invasive salmonellosis, (2) the distribution of specific Salmonella serotypes associated with invasive disease, and (3) the role of demographic characteristics in invasive salmonellosis in Michigan.

DESIGN

We conducted a cross-sectional study using laboratory-confirmed cases of salmonellosis reported to the Michigan Department of Community Health between 1995 and 2001.

METHODS

Average annual incidences (AAIs) for invasive salmonellosis were computed, and Poisson regression analysis was used to model the association between demographic attributes and invasive salmonellosis.

RESULTS

Of 6797 cases of salmonellosis, 347 (5.1%) were characterized as invasive having an AAI of 0.5/100000. A covariate-adjusted Poisson model showed children aged <1 year to be at higher risk for invasive salmonellosis compared to adults aged 40-49 years (rate ratio (RR) 8.98, 95% confidence interval (CI) 5.69-14.17). No significant differences were found between males and females (RR 1.02, 95% CI 0.83-1.26), African-Americans and Caucasians (RR 0.95, 95% CI 0.64-1.42), and urban and rural residents (RR 0.98, 95% CI 0.76-1.26). Among the most common serotypes associated with invasive salmonellosis (Heidelberg, Typhimurium, and Enteritidis), Salmonella serotype Heidelberg had the highest blood invasiveness ratio (15.79/100).

CONCLUSIONS

Children aged <1 year, especially of minority groups, are at higher risk for invasive Salmonella infections. Invasive salmonellosis may be included in the differential diagnosis of acute bacterial infections in young children with positive stool cultures for Salmonella.

Brote de gastroenteritis en una guardería causado por una cepa de Salmonella enterica serovar Typhimurium portadora del plásmido híbrido de resistencia-virulencia pUO-StVR2

OBJECTIVE

Epidemiological and microbiological study of a salmonellosis outbreak, affecting 22 children in a nursery school in Oviedo (Spain).

METHODS

Attack rates and epidemic curves were determined, and bacterial typing methods were applied.

RESULTS

The outbreak was attributed to a Salmonella enterica serovar Typhimurium strain, belonging to an emergent type characterized by the presence of a hybrid virulence-resistance plasmid of 125-130 kb, named pUO-StVR2. The attack rate of confirmed cases vs. possible cases was 27.2% vs. 23.5% for the children and 0 vs. 26.5% for the staff of the affected center. The source of the infection could not be identified. Nevertheless, according to the evolution of the cases over time, the transmission route was likely to be personal contact between the staff and children, which facilitates fecal-oral dissemination. All but one of the 27 isolates analyzed (from 22 patients) showed identical features: R-profile, plasmid-profile, RAPD-type, PFGE-type; all were non-phage-typeable, with the exception of a DT104b isolate. pUO-StVR2 is probably a derivative of the virulence plasmid pSLT from the LT2 type strain that acquired an R-region complex (ACSSuT/blaOXA-catA1-strA/ B-aadA1-sul1-sul2-tet[B]), in which the blaOXA-aadA1 genes are part of the variable region of a class 1 integron.

CONCLUSION

This outbreak is an example of how a Salmonella enterica serovar Typhimurium strain belonging to a type that is probably endemic in Spain can be transferred to the community and affect a susceptible population.

Nontyphoidal Salmonella causing focal infections in patients admitted at a Spanish general hospital during an 11-year period (1991–2001)

In focal infections (FI) caused by nontyphoidal Salmonella serotypes and recorded at a Spanish hospital 1991-2001, clinical and microbiological features were analyzed. Thirty-five revised episodes were related to infections of the digestive (10), urinary (10), pulmonar (4), vascular (4), osteoarticular (3) and central nervous (3) systems, and with a submaxillary lymph node. At least 16 episodes were associated with previous or concomitant gastroenteritis, 19 with primary or secondary bacteremia, and 18 with underlying diseases of different severity. Eighteen patients were male and 14 female (data were not available for three patients), while 1, 4, 12 and 15 patients were, respectively, categorized as children, young adults, senior adults and elderly. Sources of Salmonella strains were urine (13), blood (11), purulent abscess (8), cerebrospinal fluid (3), peritoneal fluid, pleural fluid, wound exudates, aneurism (2 of each), ascitic fluid, sputum, tracheal aspirate, needle aspirate, bone and lymph node (1 of each) samples. Only 28 Salmonella strains involved in FIs were available for further analysis. They were discriminated into 6 serotypes, and into 13 XbaI macrorestriction, 6 virulence, 11 antimicrobial resistance, 5 integron and 10 plasmid profiles. Broadly, the pattern of serotype distribution of salmonellas involved in FIs matched that of those causing gastroenteritis, with the pandemic Enteritidis and Typhimurium (18 and 6 strains, respectively) being clearly predominant. Within serotype, the same lineages (as revealed by XbaI-macrorestriction analysis as well as R- and V-profiles) were represented in both disease groups, with host-related factors apparently playing a more critical role than the individual strain in the outcome of the disease.

Large conjugative plasmids from clinical strains of Salmonella enterica serovar virchow contain a class 2 integron in addition to class 1 integrons and several non-integron-associated drug resistance determinants

Two large conjugative resistance (R) plasmids from clinical strains of Salmonella enterica serovar Virchow carried a class 2 integron with the 5' conserved sequence (5'CS)-dfrA1-sat1-aadA1-3'CS gene array, which is associated with defective Tn7 transposons. In addition, each contained a different class 1 integron (with 5'CS-aadA1-3'CS or 5'CS-sat-smr-aadA1-3'CS gene arrays) linked to Tn21-Tn9 sequences, and several non-integron-associated R determinants. An intact copy of Tn7 (including the class 2 integron) was present in the chromosome of each strain.

Recent trends in the epidemiology of non-typhoid Salmonella and antimicrobial resistance: the Israeli experience and worldwide review

PURPOSE OF REVIEW

The epidemiology of non-typhoid Salmonella has changed significantly since the turn of the century. Interestingly, non-typhoid Salmonella epidemiology in Israel mirrors some important global trends, and these new trends are reviewed. Recent research that has shed more light on the true toll of non-typhoid Salmonella epidemic and resistance is also summarized.

RECENT FINDINGS

After more than three decades of a persistent rise, reports from Israel, the US, and the UK indicate that the trend may be reversed and the incidence of NTS illnesses is starting to decline. In contrast, the rates of resistance and multidrug resistance are increasing and expanding worldwide. Of major concern are the increasing rates of multidrug resistance in Salmonella typhimurium, particularly definitive phage-type 104, the alarming increase in low-level ciprofloxacin resistance among several non-typhoid Salmonella serotypes, and the upsurge of high-level ciprofloxacin resistance, mainly in Taiwan. In Israel, high rates of resistance were reported for Salmonella virchow, which accounts for 16% of non-typhoid Salmonella illnesses, and is highly invasive in children. The true burden of Salmonella illnesses in the US was calculated as 520 cases per 100 000, compared with an annual incidence of 13.4 per 100 000 of laboratory confirmed cases. Hospitalization and death rates were 20% and 0.6%, respectively. Infection with resistant non-typhoid Salmonella isolates, and particularly S. typhimurium, increases the likelihood of hospitalization and death.

SUMMARY

Many important trends of non-typhoid Salmonella epidemiology are not restricted to a single geographic location, but spread worldwide, reflecting the global nature of the epidemic. This epidemic imposes a heavy burden worldwide.

Non-Typhi Salmonella gastroenteritis in children presenting to the emergency department: characteristics of patients with associated bacteraemia

The records of children with Salmonella gastroenteritis only (n = 97), and those with associated bacteraemia (n = 64), seen in one medical centre during a 12-year period, were analysed retrospectively. Mean patient age was 2.24 +/- 2.8 years (range, 0.05-16 years), and 49% were male. Children with bacteraemia presented after a longer duration of symptoms (7.0 +/- 6.9 vs. 3.9 +/- 4.6 days, p 0.0002), and had higher erythrocyte sedimentation rates (45 +/- 22 vs. 33 +/- 22 mm/h, p < 0.02) and lactate dehydrogenase values (924 +/- 113 vs. 685 +/- 165 IU/L, p 0.001). There was a trend in bacteraemic children towards immunosuppression (6.3% vs. 1.0%, p 0.08) and a lower number of siblings (2.9 +/- 1.9 vs. 3.8 +/- 2.7, p 0.063). Non-bacteraemic children had a more severe clinical appearance, and a higher percentage had a moderate to bad general appearance (51.5 vs. 29.7%, p < 0.01), with dehydration (37.1 vs. 18.8%, p 0.02) and vomiting (58.8 vs. 39.0%, p 0.02). Laboratory dehydration indicators were also markedly worse in non-bacteraemic children, with urine specific gravity of 1020 +/- 9.4 vs. 1013 +/- 9.0 (p 0.0002), base excess of - 4.2 +/- 3.0 vs. - 2.5 +/- 3.4 mEq/L (p 0.01), and blood urea nitrogen of 10.1 +/- 7.0 vs. 7.4 +/- 4.5 mg% (p 0.002). Thus, the clinical presentation of bacteraemic children was more gradual, and associated gastroenteritis and dehydration was less pronounced. These findings may contribute in part to the inadvertent discharge of bacteraemic children from the emergency department.

Fever without apparent source on clinical examination

PURPOSE OF REVIEW

Episodes of acute illness associated with fever are common in children. Less common but also diagnostically challenging are episodes of prolonged fever in children. This article reports recent literature that has focused on the epidemiology, pathophysiology, clinical and laboratory evaluation, and treatment of both types of episodes.

RECENT FINDINGS

A number of articles reviewed the epidemiology in several countries of bacteremia in children, including bacteremia caused by Streptococcus pneumoniae and Salmonella sp. Host susceptibility factors for bacterial illness, such as malnutrition, were reported. Diagnostic issues concerning bacteremia, including the technique of venipuncture and urine antigen testing, were of interest. A major study was published that reported a preventive approach through immunization to one type of bacteremia that caused by S. pneumoniae. Other studies addressed the issues of choice of therapy and duration of therapy in selected bacteremic disease, such as dental bacteremias and bacteremia, that were caused by Brucella melitensis. Lastly, several causes of prolonged fever (such as hemophagocytic syndrome and atypical cat scratch disease) were reported.

SUMMARY

During the review period, studies addressed diverse issues related to acute and prolonged episodes of fever in children. There was a particular emphasis on the epidemiology, diagnosis, prevention, and treatment of bacteremic illness in children.