Pediatric hypervirulent Klebsiella pneumoniae septic arthritis.

Cases of infection with hypervirulent Klebsiella pneumoniae are gradually increasing in number, and cause life-threatening community-acquired infection even in immunocompetent patients. A 14-year-old boy developed septic hip arthritis due to hypervirulent K. pneumoniae (sequence type 23, serotype K1, magA positive). The patient initially seemed to have been successfully treated with antibiotics and surgical intervention, but septic arthritis developed into osteomyelitis of the femoral head and myositis, which required long-term antibiotic therapy and additional surgical intervention. This is the first pediatric case of hypervirulent K. pneumoniae septic hip arthritis. Treatment plans should mainly consist of antibiotic therapy and surgical intervention. Clinicians, even pediatricians, in developed countries should be aware of the increasing incidence of hypervirulent Klebsiella pneumoniae infection.

Molecular epidemiologic study of community-associated methicillin-resistant Staphylococcus aureus with Panton-Valentine leukocidin gene among family members in Japan.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is one of the worldwide concerns of antimicrobial chemotherapy. An accumulation of ten patients in five families (A-E) suffering from skin and soft tissue infection (SSTI) of CA-MRSA was experienced in 2012, in Fuchu-shi, Tokyo, Japan. Molecular epidemiological investigation was performed for the 10 MRSA strains obtained from 8 children and 2 of their parents to assess endemic patterns of CA-MRSA in the community. Results of molecular typing, presence of toxin genes and antimicrobial susceptibilities were analyzed combined with the patients' clinical information. Each family had its own unique MRSA strain: A, ST30-SCCmec IVd; B, ST8-SCCmec IVd; C, ST8-SCCmec IVa; D, ST8-SCCmec IVl; E, ST8-SCCmec IVl and ST858-SCCmec IVl. Seven strains from the families A-C carried Panton-Valentine leukocidin gene. Three strains from the families D and E carried toxic shock syndrome toxin gene. Strains belonged to the same family demonstrated genetically related banding patterns of pulsed-filed gel electrophoresis. The family C experienced intrafamilial transmission of USA300-0114. Our data showed the MRSA clones disseminating in this community were highly diverse. They contained USA300-0114 clone, the rapidly distributing clone in the world, as well as MRSA clones identified in Japan. Our results suggested intrafamilial transmission of MRSA could be initial phenomenon of wide transmission in a community, therefore CA-MRSA SSTI in children and their family members should be monitored closely in order to notice the spread of highly pathogenic and transmittable strains.

High rate of inducible clindamycin resistance in Staphylococcus aureus isolates--a multicenter study in Tokyo, Japan.

The resistance of Staphylococcus aureus (S. aureus) to antibiotics is an increasing problem. Clindamycin has been used as empiric therapy for the rising incidence of community-acquired methicillin-resistant S. aureus (MRSA). As such, the local rate of inducible resistance against clindamycin is an important consideration. This multicenter study was conducted to identify the incidence of inducible clindamycin resistance of S. aureus isolates in Tokyo, the most populous city in Japan. A total of 2408 adult and pediatric samples were collected from a university hospital and two pediatric hospitals between January 2011 and December 2011. Among the 2341 samples analyzed, the incidence of inducible clindamycin resistance in erythromycin-resistant and clindamycin-susceptible/intermediate isolates was found to be 91% (n = 585), a figure much higher compared to most reports from other countries. In conclusion, we found a very high rate of inducible clindamycin resistance in macrolide-resistant S. aureus isolates in our geographic area.

Impact of Introducing a Multiplex Polymerase Chain Reaction Blood Culture Panel on Anti-Methicillin-Resistant Staphylococcus aureus (MRSA) and Carbapenem Antimicrobial Agents in a Children's Hospital.

BACKGROUND: With the advent of multiplex polymerase chain reaction (PCR) using samples from a positive blood culture, the time required to identify a pathogen has significantly shortened to a few hours. It can help us select appropriate antimicrobial agents more quickly. The present study aimed to assess the impact of using a multiplex PCR blood culture panel on the appropriate administration of antimicrobial agents. METHODS: Patients aged <16 years with culture-confirmed bacteremia at Tokyo Metropolitan Children's Medical Center were enrolled. A pre-intervention period (period I: December 2016 to December 2018) and a post-intervention period with multiplex PCR use for the confirmation of positive blood cultures (period II: December 2019 to December 2021) were compared for their effect on the use of antimicrobial agents for gram-positive cocci (GPC) and gram-negative rod (GNR) bacteremia. Data on patient background, blood culture results, and antimicrobial use were retrospectively collected from electronic medical records. RESULTS: Periods I and II had 174 and 154 patients, respectively. The median age at periods I and II was 14 (IQR 2-82) months and 12 (IQR 1-78) months, respectively. GPC bacteremia during periods I and II occurred in 140 and 115 patients, respectively. GNR during periods I and II occurred in 34 and 39 patients, respectively. Neither the vancomycin-resistance genes A/B nor the carbapenem-resistance gene were detected. The use of antimicrobial agents against anti-methicillin-resistant Staphylococcus aureus (MRSA) for GPC bacteremia decreased from 103/140 cases (73%) in period I to 56/115 cases (49%) in period II (p=0.047). The use of carbapenems for GNR bacteremia did not change significantly, at 23/34 (68%) in period I and 34/39 (87%) in period II (p=0.47). CONCLUSION: Introducing multiplex PCR for pediatric bacteremia decreased the use of anti-MRSA antimicrobial agents but not of carbapenems.