crossmark
The Brief Case (For answers to the self-assessment questions and take-home points, see page 822 in this issue [doi:10.1128/JCM.0265015].)
Kingella kingae Septic Arthritis in a 14-Month-Old Child Erin McElvania TeKippe Departments of Pathology and Pediatrics, University of Texas Southwestern, and Departments of Pathology and Laboratory Medicine, Children’s Health, Dallas, Texas, USA
CASE
A
14-month-old girl presented to the emergency department with pain and swelling of her left ankle. The patient was in her usual good state of health up until the morning of presentation. When her mother picked her up from day care, she refused to bear weight on her left leg. The day care noted that she had been fussy during the day, with reduced oral intake and decreased sleep, but had no fever, vomiting, or diarrhea. The patient had no significant past medical history, had no family history of skin and soft tissue infections, and was fully vaccinated. In the emergency department, the patient had a C-reactive protein level within normal limits and a mildly elevated erythrocyte sedimentation rate of 35 mm/h (reference range, 0 to 15 mm/ h). Her physical exam and X rays were concerning for septic arthritis of the ankle. An incision and drainage of the ankle was performed, and grossly purulent joint fluid was collected from the site. The fluid was bloody and had 5,112 nucleated cells/mm3, with a differential of 66% neutrophils, 24% lymphocytes, and 10% monocytes. The patient was empirically placed on intravenous clindamycin (10 mg/kg of body weight/dose every 6 h) and ceftriaxone (50 mg/kg/dose every 24 h). Gram stain results of the joint fluid revealed many polymorphonuclear cells, moderate red blood cells, and no microorganisms. The specimen was inoculated onto 5% sheep blood, chocolate, MacConkey, and colistin nalidixic acid (CNA) agars. Approximately 0.5 ml of the specimen was injected into an aerobic blood culture bottle (BD Bactec Peds Plus/F) and incubated in an automated blood culture instrument (BD Bactec; Becton Dickinson, Franklin Lakes, NJ, USA). No bacteria were isolated on solid media. After 46 h of incubation, the blood culture bottle containing joint fluid signaled positive. The Gram stain showed short, plump Gram-negative rods. The positive joint fluid broth was subcultured to solid media and incubated at 35°C with 5% CO2. After 36 h of incubation, the cultures produced small, beta-hemolytic colonies on 5% sheep blood agar and small colonies on chocolate agar (Fig. 1). No growth was observed on MacConkey or CNA agar. The isolate was oxidase positive and catalase negative. The organism was identified as Kingella kingae by matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) (Bruker Biotyper, software version v3.3.1.0; Bruker Daltonics, Billerica, MA, USA), achieving a score of 2.126, which is acceptable for genus- and species-level identification.
(CDC) (1). She described a novel bacterium isolated from the respiratory tract, blood, bone, and joint fluid. To honor King, the organism was originally named Moraxella kingii but was later given its own genus and renamed Kingella kingae. Kingella spp. are part of the Neisseriaceae family. There are now four recognized species of Kingella, three which colonize the human oral cavity, namely, K. denitrificans, K. oralis, and K. kingae, and one species, K. potus, which is a suspected zoonotic mouth-colonizing bacterium that was initially identified from a kinkajou bite wound. K. kingae is part of the normal flora of the human oropharynx, but interestingly, it does not seem to be a part of the nasopharyngeal flora, as it is rarely isolated from that site (1). The organism is a frequent colonizer of young children. A study of 716 healthy children aged 2 to 30 months, of which half attended day care, underwent serial culture for isolation K. kingae (2). No children under 6 months of age were colonized, 1.5% of 6 month olds were colonized, and 9.6 to 12% of children aged 12 to 24 months were colonized with K. kingae (peak colonization). By 30 months of age, K. kingae colonization had declined to 5.3%. It is believed that invasive K. kingae infections occur when bacteria colonizing host epithelial cells gain access to the bloodstream, which allows dissemination to distal body sites. The age at which patients are asymptomatically colonized is tightly correlated with the age at which children are at highest risk for K. kingae bone and joint infections (2). It is now widely recognized that K. kingae is a common cause of bacteremia without a focus (as a member of the HACEK group of organisms [a group of Gram-negative bacilli consisting of Haemophilus spp., Aggregatibacter spp., Cardiobacterium spp., Eikenella corrodens, and Kingella spp.], known to cause Gram-negative endocarditis), and it is also the most common cause of septic arthritis and osteomyelitis in children 6 to 36 months of age (1, 3). The clinical presentation of K. kingae septic joint infection is often mild, making clinical detection by physical exam challenging. K. kingae organisms appear as Gram-negative coccobacilli or plump, short rods on a Gram stain (Fig. 2), where they are generally seen in pairs or short chains. They are facultative anaerobes but show increased growth in the presence of CO2. Like Moraxella and Neisseria, Kingella spp. grow on 5% sheep blood and choco-
Citation McElvania TeKippe E. 2016. Kingella kingae septic arthritis in a 14-monthold child. J Clin Microbiol 54:513–515. doi:10.1128/JCM.02649-15. Editor: C.-A. D. Burnham
DISCUSSION
Address correspondence to [email protected].
Kingella was originally discovered in the 1960s by Elizabeth O. King while she was working at the then Center for Disease Control
Copyright © 2016, American Society for Microbiology. All Rights Reserved.
March 2016 Volume 54 Number 3
Journal of Clinical Microbiology
jcm.asm.org
513
The Brief Case
FIG 2 Colony Gram stain of K. kingae demonstrating short, plump Gramnegative rods in pairs and occasionally short chains.
FIG 1 Kingella kingae growth on media after 36 h of incubation. (A) Betahemolytic colonies on 5% sheep blood agar; (B) growth on chocolate medium.
late agars but do not grow on MacConkey agar or CNA agars. On sheep blood agar, K. kingae exhibits a beta-hemolysis. Isolates may exhibit either of two colonial morphologies. Our isolate grew smooth colonies with a central papilla upon maturation, but other isolates may spread and pit the agar. Biochemically, K. kingae organisms are oxidase positive (except in very rare cases) but negative for indole, catalase, and urease. They are also nonmotile. Isolates of K. kingae produce acid from glucose and often from maltose as well. Several identification systems are reported to perform well for the identification of K. kingae, including the API NH card, Vitek 2, 16S rRNA gene sequencing, and MALDITOF MS (3). Until recently, K. kingae has been an underappreciated cause of bone and joint infections. Between its discovery in the 1960s and 1990, there were very few reports of K. kingae infection in the literature (1). This is likely due to the fact that K. kingae is very fastidious and rarely grows in culture, therefore underrepresenting the number of infections caused by the organism. To prevent desiccation during transport, some orthopedic surgeons inoculate chocolate agar plates in the surgical suite, immediately after removal of a specimen from the patient, although plating of clinical specimens by nonlaboratorians may result in increased contamination. Studies have demonstrated that in microbiology laboratories, inoculating specimens into blood culture bottles greatly improves the recovery of K. kingae from joint fluid. In one study, 216 pediatric
514
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joint fluid specimens were inoculated into Bactec blood culture bottles, and specimens were also plated to solid media for routine culture (4). The study found that 14 specimens grew K. kingae, and in all but one case, the organism was detected only from the positive blood culture bottle and did not grow on solid media. This was the case with our patient’s specimen, as it was isolated only from fluid inoculated into a blood culture bottle and did not grow when the specimen was plated directly to solid media. Due to the difficulty of detecting this organism by culture, K. kingae-specific PCR and 16S rRNA gene sequencing directly from the patient specimen have become popular methods of detecting K. kingae from pediatric joint fluid specimens (1). In a study of 61 pediatric osteoarticular specimens, only one specimen was positive by culture alone, which included incubation of fluid in blood culture bottles (5). 16S rRNA gene sequencing and K. kingaespecific PCR were performed on all culture-negative specimens. 16S rRNA gene sequencing detected K. kingae in an additional 16 specimens that were negative by culture alone. K. kingae-specific PCR confirmed the presence of K. kingae in all 16 specimens in which it was identified by 16S sequencing and detected K. kingae in 6 additional specimens. These data mirror the results of other studies which have found that K. kingae-specific PCR is more sensitive than other tests for detection of K. kingae, while 16S rRNA is able to detect K. kingae as well as a broad range of other organisms. Both methods are more sensitive than culture for detecting K. kingae. Due to the fastidious nature of the organism, antimicrobial susceptibility testing is not performed in most clinical microbiology laboratories. In general, Kingella spp. are susceptible to -lactam antibiotics, macrolides, tetracyclines, and quinolones. Some isolates of Kingella produce -lactamases, but these isolates are susceptible to -lactam/-lactamase inhibitors. If detected and promptly treated, K. kingae bone and joint infections generally resolve rapidly with no long-term sequelae (1, 3). In conclusion, K. kingae bone and joint infections can be difficult to detect, as they commonly present with mild symptoms, and the organism is very fastidious and often does not grow in culture. Inoculation of joint fluid into blood culture bottles and the use of molecular assays have increased the sensitivity of detection of K.
Journal of Clinical Microbiology
March 2016 Volume 54 Number 3
The Brief Case
kingae, which is now recognized as the most common cause of septic arthritis and osteomyelitis in children 6 to 36 months of age.
1. In what age range are patients most likely to acquire septic arthritis due to Kingella kingae? (a) ⬍6 months of age (b) 6 to 36 months (c) 15 to 25 years (d) 65 years of age 2. What is the source of K. kingae bone and joint infections? (a) Invasion of the bloodstream by colonizing bacteria (b) Water exposure (c) Entry through abrasions in the skin (d) Arthropod bite 3. Which of the methods below have been shown to improve recovery of Kingella spp. in clinical microbiology laboratories?
March 2016 Volume 54 Number 3
(c) Incubation of media under anaerobic conditions (d) Inoculation of joint fluid specimens into blood culture bottles
SELF-ASSESSMENT QUESTIONS
(a) Culture on MacConkey agar
(b) Refrigeration of joint fluid specimens prior to plating
REFERENCES 1. Yagupsky P. 2015. Kingella kingae: carriage, transmission, and disease. Clin Microbiol Rev 28:54 –79. http://dx.doi.org/10.1128/CMR.00028-14. 2. Amit U, Flaishmakher S, Dagan R, Porat N, Yagupsky P. 2014. Agedependent carriage of Kingella kingae in young children and turnover of colonizing strains. J Pediatr Infect Dis Soc 3:160 –162. http://dx.doi.org/10 .1093/jpids/pit003. 3. Zbinden R. 2015. Aggregatibacter, Capnocytophaga, Eikenella, Kingella, Pasteurella, and other fastidious or rarely encountered Gram-negative rods, p 652– 666. In Jorgensen JH, Pfaller MA (ed), Manual of clinical microbiology, 11th ed. ASM Press, Washington DC. 4. Yagupsky P, Dagan R, Howard CW, Einhorn M, Kassis I, Simu A. 1992. High prevalence of Kingella kingae in joint fluid from children with septic arthritis revealed by the BACTEC blood culture system. J Clin Microbiol 30:1278 –1281. 5. Chometon S, Benito Y, Chaker M, Boisset S, Ploton C, Berard J, Vandenesch F, Freydiere AM. 2007. Specific real-time polymerase chain reaction places Kingella kingae as the most common cause of osteoarticular infections in young children. Pediatr Infect Dis J 26:377–381. http://dx.doi .org/10.1097/01.inf.0000259954.88139.f4.
Journal of Clinical Microbiology
jcm.asm.org
515
The Brief Case (For answers to the self-assessment questions and take-home points, see page 822 in this issue [doi:10.1128/JCM.0265015].)
Kingella kingae Septic Arthritis in a 14-Month-Old Child Erin McElvania TeKippe Departments of Pathology and Pediatrics, University of Texas Southwestern, and Departments of Pathology and Laboratory Medicine, Children’s Health, Dallas, Texas, USA
CASE
A
14-month-old girl presented to the emergency department with pain and swelling of her left ankle. The patient was in her usual good state of health up until the morning of presentation. When her mother picked her up from day care, she refused to bear weight on her left leg. The day care noted that she had been fussy during the day, with reduced oral intake and decreased sleep, but had no fever, vomiting, or diarrhea. The patient had no significant past medical history, had no family history of skin and soft tissue infections, and was fully vaccinated. In the emergency department, the patient had a C-reactive protein level within normal limits and a mildly elevated erythrocyte sedimentation rate of 35 mm/h (reference range, 0 to 15 mm/ h). Her physical exam and X rays were concerning for septic arthritis of the ankle. An incision and drainage of the ankle was performed, and grossly purulent joint fluid was collected from the site. The fluid was bloody and had 5,112 nucleated cells/mm3, with a differential of 66% neutrophils, 24% lymphocytes, and 10% monocytes. The patient was empirically placed on intravenous clindamycin (10 mg/kg of body weight/dose every 6 h) and ceftriaxone (50 mg/kg/dose every 24 h). Gram stain results of the joint fluid revealed many polymorphonuclear cells, moderate red blood cells, and no microorganisms. The specimen was inoculated onto 5% sheep blood, chocolate, MacConkey, and colistin nalidixic acid (CNA) agars. Approximately 0.5 ml of the specimen was injected into an aerobic blood culture bottle (BD Bactec Peds Plus/F) and incubated in an automated blood culture instrument (BD Bactec; Becton Dickinson, Franklin Lakes, NJ, USA). No bacteria were isolated on solid media. After 46 h of incubation, the blood culture bottle containing joint fluid signaled positive. The Gram stain showed short, plump Gram-negative rods. The positive joint fluid broth was subcultured to solid media and incubated at 35°C with 5% CO2. After 36 h of incubation, the cultures produced small, beta-hemolytic colonies on 5% sheep blood agar and small colonies on chocolate agar (Fig. 1). No growth was observed on MacConkey or CNA agar. The isolate was oxidase positive and catalase negative. The organism was identified as Kingella kingae by matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS) (Bruker Biotyper, software version v3.3.1.0; Bruker Daltonics, Billerica, MA, USA), achieving a score of 2.126, which is acceptable for genus- and species-level identification.
(CDC) (1). She described a novel bacterium isolated from the respiratory tract, blood, bone, and joint fluid. To honor King, the organism was originally named Moraxella kingii but was later given its own genus and renamed Kingella kingae. Kingella spp. are part of the Neisseriaceae family. There are now four recognized species of Kingella, three which colonize the human oral cavity, namely, K. denitrificans, K. oralis, and K. kingae, and one species, K. potus, which is a suspected zoonotic mouth-colonizing bacterium that was initially identified from a kinkajou bite wound. K. kingae is part of the normal flora of the human oropharynx, but interestingly, it does not seem to be a part of the nasopharyngeal flora, as it is rarely isolated from that site (1). The organism is a frequent colonizer of young children. A study of 716 healthy children aged 2 to 30 months, of which half attended day care, underwent serial culture for isolation K. kingae (2). No children under 6 months of age were colonized, 1.5% of 6 month olds were colonized, and 9.6 to 12% of children aged 12 to 24 months were colonized with K. kingae (peak colonization). By 30 months of age, K. kingae colonization had declined to 5.3%. It is believed that invasive K. kingae infections occur when bacteria colonizing host epithelial cells gain access to the bloodstream, which allows dissemination to distal body sites. The age at which patients are asymptomatically colonized is tightly correlated with the age at which children are at highest risk for K. kingae bone and joint infections (2). It is now widely recognized that K. kingae is a common cause of bacteremia without a focus (as a member of the HACEK group of organisms [a group of Gram-negative bacilli consisting of Haemophilus spp., Aggregatibacter spp., Cardiobacterium spp., Eikenella corrodens, and Kingella spp.], known to cause Gram-negative endocarditis), and it is also the most common cause of septic arthritis and osteomyelitis in children 6 to 36 months of age (1, 3). The clinical presentation of K. kingae septic joint infection is often mild, making clinical detection by physical exam challenging. K. kingae organisms appear as Gram-negative coccobacilli or plump, short rods on a Gram stain (Fig. 2), where they are generally seen in pairs or short chains. They are facultative anaerobes but show increased growth in the presence of CO2. Like Moraxella and Neisseria, Kingella spp. grow on 5% sheep blood and choco-
Citation McElvania TeKippe E. 2016. Kingella kingae septic arthritis in a 14-monthold child. J Clin Microbiol 54:513–515. doi:10.1128/JCM.02649-15. Editor: C.-A. D. Burnham
DISCUSSION
Address correspondence to [email protected].
Kingella was originally discovered in the 1960s by Elizabeth O. King while she was working at the then Center for Disease Control
Copyright © 2016, American Society for Microbiology. All Rights Reserved.
March 2016 Volume 54 Number 3
Journal of Clinical Microbiology
jcm.asm.org
513
The Brief Case
FIG 2 Colony Gram stain of K. kingae demonstrating short, plump Gramnegative rods in pairs and occasionally short chains.
FIG 1 Kingella kingae growth on media after 36 h of incubation. (A) Betahemolytic colonies on 5% sheep blood agar; (B) growth on chocolate medium.
late agars but do not grow on MacConkey agar or CNA agars. On sheep blood agar, K. kingae exhibits a beta-hemolysis. Isolates may exhibit either of two colonial morphologies. Our isolate grew smooth colonies with a central papilla upon maturation, but other isolates may spread and pit the agar. Biochemically, K. kingae organisms are oxidase positive (except in very rare cases) but negative for indole, catalase, and urease. They are also nonmotile. Isolates of K. kingae produce acid from glucose and often from maltose as well. Several identification systems are reported to perform well for the identification of K. kingae, including the API NH card, Vitek 2, 16S rRNA gene sequencing, and MALDITOF MS (3). Until recently, K. kingae has been an underappreciated cause of bone and joint infections. Between its discovery in the 1960s and 1990, there were very few reports of K. kingae infection in the literature (1). This is likely due to the fact that K. kingae is very fastidious and rarely grows in culture, therefore underrepresenting the number of infections caused by the organism. To prevent desiccation during transport, some orthopedic surgeons inoculate chocolate agar plates in the surgical suite, immediately after removal of a specimen from the patient, although plating of clinical specimens by nonlaboratorians may result in increased contamination. Studies have demonstrated that in microbiology laboratories, inoculating specimens into blood culture bottles greatly improves the recovery of K. kingae from joint fluid. In one study, 216 pediatric
514
jcm.asm.org
joint fluid specimens were inoculated into Bactec blood culture bottles, and specimens were also plated to solid media for routine culture (4). The study found that 14 specimens grew K. kingae, and in all but one case, the organism was detected only from the positive blood culture bottle and did not grow on solid media. This was the case with our patient’s specimen, as it was isolated only from fluid inoculated into a blood culture bottle and did not grow when the specimen was plated directly to solid media. Due to the difficulty of detecting this organism by culture, K. kingae-specific PCR and 16S rRNA gene sequencing directly from the patient specimen have become popular methods of detecting K. kingae from pediatric joint fluid specimens (1). In a study of 61 pediatric osteoarticular specimens, only one specimen was positive by culture alone, which included incubation of fluid in blood culture bottles (5). 16S rRNA gene sequencing and K. kingaespecific PCR were performed on all culture-negative specimens. 16S rRNA gene sequencing detected K. kingae in an additional 16 specimens that were negative by culture alone. K. kingae-specific PCR confirmed the presence of K. kingae in all 16 specimens in which it was identified by 16S sequencing and detected K. kingae in 6 additional specimens. These data mirror the results of other studies which have found that K. kingae-specific PCR is more sensitive than other tests for detection of K. kingae, while 16S rRNA is able to detect K. kingae as well as a broad range of other organisms. Both methods are more sensitive than culture for detecting K. kingae. Due to the fastidious nature of the organism, antimicrobial susceptibility testing is not performed in most clinical microbiology laboratories. In general, Kingella spp. are susceptible to -lactam antibiotics, macrolides, tetracyclines, and quinolones. Some isolates of Kingella produce -lactamases, but these isolates are susceptible to -lactam/-lactamase inhibitors. If detected and promptly treated, K. kingae bone and joint infections generally resolve rapidly with no long-term sequelae (1, 3). In conclusion, K. kingae bone and joint infections can be difficult to detect, as they commonly present with mild symptoms, and the organism is very fastidious and often does not grow in culture. Inoculation of joint fluid into blood culture bottles and the use of molecular assays have increased the sensitivity of detection of K.
Journal of Clinical Microbiology
March 2016 Volume 54 Number 3
The Brief Case
kingae, which is now recognized as the most common cause of septic arthritis and osteomyelitis in children 6 to 36 months of age.
1. In what age range are patients most likely to acquire septic arthritis due to Kingella kingae? (a) ⬍6 months of age (b) 6 to 36 months (c) 15 to 25 years (d) 65 years of age 2. What is the source of K. kingae bone and joint infections? (a) Invasion of the bloodstream by colonizing bacteria (b) Water exposure (c) Entry through abrasions in the skin (d) Arthropod bite 3. Which of the methods below have been shown to improve recovery of Kingella spp. in clinical microbiology laboratories?
March 2016 Volume 54 Number 3
(c) Incubation of media under anaerobic conditions (d) Inoculation of joint fluid specimens into blood culture bottles
SELF-ASSESSMENT QUESTIONS
(a) Culture on MacConkey agar
(b) Refrigeration of joint fluid specimens prior to plating
REFERENCES 1. Yagupsky P. 2015. Kingella kingae: carriage, transmission, and disease. Clin Microbiol Rev 28:54 –79. http://dx.doi.org/10.1128/CMR.00028-14. 2. Amit U, Flaishmakher S, Dagan R, Porat N, Yagupsky P. 2014. Agedependent carriage of Kingella kingae in young children and turnover of colonizing strains. J Pediatr Infect Dis Soc 3:160 –162. http://dx.doi.org/10 .1093/jpids/pit003. 3. Zbinden R. 2015. Aggregatibacter, Capnocytophaga, Eikenella, Kingella, Pasteurella, and other fastidious or rarely encountered Gram-negative rods, p 652– 666. In Jorgensen JH, Pfaller MA (ed), Manual of clinical microbiology, 11th ed. ASM Press, Washington DC. 4. Yagupsky P, Dagan R, Howard CW, Einhorn M, Kassis I, Simu A. 1992. High prevalence of Kingella kingae in joint fluid from children with septic arthritis revealed by the BACTEC blood culture system. J Clin Microbiol 30:1278 –1281. 5. Chometon S, Benito Y, Chaker M, Boisset S, Ploton C, Berard J, Vandenesch F, Freydiere AM. 2007. Specific real-time polymerase chain reaction places Kingella kingae as the most common cause of osteoarticular infections in young children. Pediatr Infect Dis J 26:377–381. http://dx.doi .org/10.1097/01.inf.0000259954.88139.f4.
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