Nahed Abdel-Haq

Yersinia enterocolitica infection in children.

Background. Yersinia enterocolitica can cause illness ranging from self-limited enteritis to life-threatening systemic infection. The present study was undertaken to review the epidemiology, clinical manifestations, complications and outcome of Y. enterocolitica enteritis in children seen at a large children’s hospital. Methods. The project consisted of a retrospective chart review of medical and microbiologic records of all children with stool cultures positive for Y. enterocolitica during a 7-year period. Results. The review included 142 patients with Y. enterocolitica enteritis. Patients’ ages ranged from 18 days to 12 years, and the majority (85%) were younger than 1 year. Most patients presented during November, December and January. History of exposure to chitterlings (raw pork intestines) at home was elicited in 25 of 30 cases. Y. enterocolitica accounted for 12.6% (142 of 1120) of all bacterial intestinal pathogens isolated during the study period. Blood cultures were positive in 7(9%) of 78 patients; 6 were younger than 1 year and one 12-year-old had sickle cell disease. Of 132 isolates tested all were susceptible to trimethoprim-sulfamethoxazole, tobramycin and gentamicin; the majority were susceptible to cefotaxime (99%), ceftazidime (89%) and cefuroxime (88%). All bacteremic patients responded to cefotaxime treatment. Follow-up evaluation of 40 ambulatory patients revealed no difference in clinical improvement between those treated with oral trimethoprim-sulfamethoxazole (17 of 23) and those who were not treated (8 of 17) (P = 0.1). Conclusion. Y. enterocolitica is an important cause of enteritis in our young patient population during the winter holidays. Exposure of infants to chitterlings appears to be a risk factor. Infants younger than 3 months are at increased risk for bacteremia. Cefotaxime is effective in the treatment of Y. enterocolitica bacteremia; however, the role of oral antibiotics in the management of enteritis needs further evaluation.

Retropharyngeal abscess in children: the emerging role of group A beta hemolytic Streptococcus

Background: Because of a recent increase in the number of cases of retropharyngeal abscess (RPA) admitted to our hospital, we reviewed the incidence, microbiology, and treatment outcome of RPA during an 11-year period (1993–2003). Methods: A retrospective review of medical records of children with RPA. Results: Sixty-seven children (46 males) with RPA were identified, representing a 4.5-fold increase in incidence over a previous 12-year period. The majority (66%) of patients presented during the last 4 years. Computed tomography revealed inflammatory or ring enhancing lesion in all patients. Abscess drainage was performed in 51 (76%) patients. A total of 101 isolates (84 aerobes, 17 anaerobes) were recovered from 41 specimens (a mean of 2.5 isolates per specimen). Group A beta hemolytic streptococcus (GABHS) was recovered from 22 (54%) of 41 specimens compared with 6 (35%) of 17 over the previous 12 years. Treatment included IV antibiotics: ampicillin/sulbactam or clindamycin plus either cefuroxime or ceftriaxone, followed by oral amoxicillin/ clavulanate or clindamycin. All patients recovered. Conclusions: RPA, an aerobic/anaerobic polymicrobial infection, is increasing in frequency and is associated with increased recovery of GABHS in our patients. Whether this rise in incidence is due to increased invasiveness of GABHS strains is to be determined.

An outbreak of carbapenem-resistant Acinetobacter baumannii infection in a neonatal intensive care unit: investigation and control.

OBJECTIVE To investigate the mode of transmission of and assess control measures for an outbreak of carbapenem-resistant (multidrug-resistant) Acinetobacter baumannii infection involving 6 premature infants. DESIGN An outbreak investigation based on medical record review was performed for each neonate during the outbreak (from November 2008 through January 2009) in conjunction with an infection control investigation. SETTING A 36-bed, level 3 neonatal intensive care unit in a university-affiliated teaching hospital in Detroit, Michigan. INTERVENTIONS Specimens were obtained for surveillance cultures from all infants in the unit. In addition, geographic cohorting of affected infants and their nursing staff, contact isolation, re-emphasis of adherence to infection control practices, environmental cleaning, and use of educational modules were implemented to control the outbreak. RESULTS Six infants (age, 10-197 days) with multidrug-resistant A. baumannii infection were identified. All 6 infants were premature (gestational age, 23-30 weeks) and had extremely low birth weights (birth weight, 1000 g or less). Conditions included conjunctivitis (2 infants), pneumonia (4 infants), and bacteremia (1 infant). One infant died of causes not attributed to infection with the organism; the remaining 5 infants were discharged home. All surveillance cultures of unaffected infants yielded negative results. CONCLUSIONS The spread of multidrug-resistant A. baumannii infection was suspected to be due to staff members who spread the pathogen through close contact with infants. Clinical staff recognition of the importance of multidrug-resistant A. baumannii recovery from neonatal intensive care unit patients, geographic cohorting of infected patients, enhanced infection control practices, and staff education resulted in control of the spread of the organism.

Cytokine regulation of CD40 expression in fetal human astrocyte cultures

CD40 can participate in inflammatory processes after binding its cognate ligand (CD40L). We found that fetal human astrocytes constitutively express CD40 mRNA and protein. Upon incubating cultures with proinflammatory cytokines (TNF-alpha, IL-1beta and IFN-gamma) or with lipopolysaccharide (LPS), CD40 expression was increased. No change in CD40 expression was noted in astrocyte cultures incubated with IL-6, HIV or gp41. Astrocytes also showed increased release of proinflammatory cytokines TNF-alpha, IL-1beta and IL-6 after incubation with CD40L peptide. These observations suggest a role for CD40 in central nervous system (CNS) inflammation and that CD40/CD40L autocrine or paracrine pathways may mediate this role.

Increased prevalence of methicillin-resistant Staphylococcus aureus nasal colonization in household contacts of children with community acquired disease

BackgroundTo measure Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization prevalence in household contacts of children with current community associated (CA)-MRSA infections (study group) in comparison with a group of household contacts of children without suspected Staphylococcus aureus infection (a control group).MethodsThis is a cross sectional study. Cultures of the anterior nares were taken. Relatedness of isolated strains was tested using pulse field gel electrophoresis (PFGE).ResultsThe prevalence of MRSA colonization in the study group was significantly higher than in the control group (18/77 (23%) vs 3/77 (3.9%); p ≤ 0.001). The prevalence of SA colonization was 28/77 (36%) in the study group and 16/77 (21%) in the control group (p = 0.032). The prevalence of SA nasal colonization among patients was 6/24 (25%); one with methicillin-susceptible S. aureus (MSSA) and 5 with MRSA. In the study (patient) group, 14/24 (58%) families had at least one household member who was colonized with MRSA compared to 2/29 (6.9%) in the control group (p = 0.001). Of 69 total isolates tested by PFGE, 40 (58%) were related to USA300. Panton-Valetine leukocidin (PVL) genes were detected in 30/52 (58%) tested isolates. Among the families with ≥1 contact colonized with MRSA, similar PFGE profiles were found between the index patient and a contact in 10/14 families.ConclusionsPrevalence of asymptomatic nasal carriage of MRSA is higher among household contacts of patients with CA-MRSA disease than control group. Decolonizing such carriers may help prevent recurrent CA-MRSA infections.

Methicillin-resistant Staphylococcus aureus (MRSA) in hospitalized children: correlation of molecular analysis with clinical presentation and antibiotic susceptibility testing (ABST) results.

The molecular analysis of methicillin-resistant Staphylococcus aureus (MRSA) from 98 children admitted to the Children’s Hospital of Michigan, Detroit, MI, with serious MRSA infections during 2006–2007 was correlated with risk factors, clinical features, and antibiotic susceptibility testing (ABST) results. Isolates were characterized by staphylococcal cassette chromosome (SCC) mec type, the presence of Panton-Valentine leukocidin (PVL) genes, repetitive sequence (rep) polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE), requirement for surgical intervention, antibiograms, and response to therapy. rep-PCR was more rapid than PFGE typing and correlated well. SCCmec type IV-containing isolates caused 92.8% of all infections, but the demographics and diseases associated with subtypes IVa and IVd differed. Subtype IVa (all PFGE type USA300 and PVL-positive) was identified in 81/93 (87.1%) of patients with community-onset (CO) MRSA, including 21/35 of those with risk factors for health care-associated (HA) infection. All other clones were PVL-negative. Subtype IVd (10 isolates; 9 USA800 and 1 eMRSA15) caused mainly HA-MRSA and no skin and soft tissue infections (SSTI). Seven classic HA-MRSA strains (SCCmec types II [6; 3 USA100 and 3 USA600] and III [1; USA200]) caused HA and hospital-onset (HO) infections. Surgical intervention was required in 68/81 patients infected with USA300 and 8/17 of the others. Most USA300 were susceptible (S) to clindamycin (CD) and patients were treated with CD alone or in combination. The other isolates were generally treated with vancomycin (VA) alone or in combination.

Retropharyngeal abscess in children: the rising incidence of methicillin-resistant Staphylococcus aureus.

Background: Because of a recent upsurge in retropharyngeal abscess (RPA) cases due to community-associated methicillin-resistant Staphylococcus aureus (MRSA), we reevaluated the microbiology, clinical manifestations and treatment outcome of RPA over the past 6 years (2004 to 2010). Findings were compared with those of a previous 11-year study (1993 to 2003) period. Methods: A retrospective review of medical records of children with RPA. Results: One hundred fourteen children (61 males) with RPA were identified representing a 2.8-fold increase in incidence (per 10,000 admissions) over the previous 11-year period. Abscess drainage was performed in 74 (65%). A total of 116 isolates (93 aerobes, 23 anaerobes) were recovered from 66 specimens. S. aureus was recovered from 25 (38%) of the 66 specimens compared with 2 (4.9%) of 41 in the previous 11 years; 16 (64%) of 25 were MRSA compared with none in the previous 11 years. Children whose abscess grew MRSA were younger (mean 11 months) than the others (mean 62 months) (P < 0.001) and required longer duration of hospitalization (mean 8.8 days) than the rest (mean 4.5 days) (P = 0.002). Five children had mediastinitis; all caused by MRSA. All MRSA isolates were susceptible to clindamycin. Ceftriaxone plus clindamycin was the most common treatment regimen. All patients had resolution of their abscesses. Conclusions: RPA has increased in frequency in our pediatric population with an associated increase of Staphylococcus aureus, mainly community-associated MRSA. This is likely due to the overall increase in community-associated MRSA infections in our pediatric patients. Treatment with ceftriaxone and clindamycin in addition to surgical drainage was effective.

Asaia lannaensis bloodstream infection in a child with cancer and bone marrow transplantation

A 3-year-old Caucasian boy with medulloblastoma in relapse, who had received an autologous haematopoietic stem cell transplant (AHSCT), underwent chemotherapy and craniospinal radiation followed by a second AHSCT. The patient received a preparative chemotherapy regimen of carboplatin, etoposide and melphalan followed by the AHSCT at a CD34+ dose of 3.73610 cells kg. His post-transplant course was complicated by severe mucositis, pancytopenia and Clostridium difficile colitis diagnosed on day 6 post-transplantation (PT). He was successfully treated for the C. difficile colitis with metronidazole. On day 7, he developed hypertonia and spastic posturing. Magnetic resonance imaging of the brain showed an old subdural haematoma and possible radiation necrosis in the brainstem. He underwent craniotomy and drainage of the haematoma, and was treated with intravenous meropenem and vancomycin because of the neutropenia and mucositis. He improved and engrafted by day 12 PT. His antibiotic treatment was changed to intravenous cefepime. On day 14 PT, he developed tachycardia, hypotension and fever up to 40.1 uC. Blood cultures were obtained from both lumens of the CVC. Intravenous meropenem and vancomycin were restarted. Both blood cultures grew Gram-negative bacilli within 12–18 h. The patient remained febrile and hypotensive and tobramycin was added to his treatment regimen. Because the CVC was a possible source of infection, the catheter was locked with 70 % ethanol (the catheter volume plus 0.1 ml) according to our institutional protocol for sterilizing CVCs without removal. After 24 h, the catheter was flushed with normal saline (Dannenberg et al., 2003; Onland et al., 2006).

Epstein Barr Virus—Associated Acute Acalculous Cholecystitis: A Rare Occurrence but Favorable Outcome

Acute infection with Epstein Barr virus (EBV) in childhood is usually almost asymptomatic, whereas it presents as typical infectious mononucleosis (sore throat, fever, cervical lymphadenopathy, and hepatosplenomegaly) in about 50% of adolescents and young adults with primary infection. Serious complications like airway obstruction, chronic interstitial pneumonitis, splenic rupture, severe thrombocytopenia, hemophagocytic syndrome, aseptic meningitis, or meningoencephalitis are very rare. Cholestatic hepatitis with mild liver dysfunction has been reported in more than 90% of patients with primary EBV infection, but severe liver dysfunction or gallbladder (GB) involvement is rare. A literature review found that only a few cases of acalculous cholecystitis have been reported during the course of primary EBV infection, all during the last 3 years. We report the case of a teenaged girl with acute acalculous cholecystitis (AAC) caused by EBV infection, the first in the United States, and review the relevant literature.

Emergence of human rotavirus genotype G9 in metropolitan Detroit between 2007 and 2009

Between January 2007 and April 2009, rotavirus (RV)-positive stool samples from 238 children with acute gastroenteritis, seen at Childrens Hospital of Michigan in Detroit, USA, were collected and RV genotyping was performed. G and P genotypes were determined by RT-PCR and nucleotide sequencing was conducted on selected G9 and P[6] strains. Correlation between the severity of gastroenteritis episode and the infecting G genotype was done using a 14-point scoring system. The predominant G genotype was G9 (39.5 %), followed by G1 (35.3 %) and G4 (15.5 %), while P[8] was the most prevalent P genotype (66.5 %), followed by P[4] (21.9 %) and P[6] (11.2 %). The gene combinations G1P[8] and G9P[8] were the most prevalent (21.4 % and 20.6 %, respectively), followed by G4P[8] (13 %) and G9P[6] (8.8 %). Immunization data showed that only 17/238 (7.1 %) children received ≥one dose of RV vaccine (the pentavalent vaccine RotaTeq or the monovalent vaccine Rotarix) and that 10/17 were infected with G4P[8] strains. Severity of RV gastroenteritis episodes was not related to the infecting G genotype. Our results suggest a high proportion of genotype G9 strains in combination with P[8], P[6] and P[4] specificity circulating in the metropolitan Detroit area. While the protective efficacy of the RV vaccines has been demonstrated against G9P[8] strains, the level of cross-protection offered by the vaccines against G9 strains with P[6] and P[4] genotypes in the Detroit paediatric population remains to be determined.