BRIEF REPORT paronychia, bacteriology of
Aerobic and Anaerobic Microbiology of Paronychia Pus specimens from 28 patients with paronychia of the finger yielded bacterial growth by techniques for cultivation of aerobic and anaerobic bacteria. AnaeroMc and aerobic organisms only were isolated in pure culture in five (18%) and eight palients (29%), respectively; mixed aerobic and anaerobic flora were preser~t in 15 patients (54%). Seventy-two isolates were recovered, or 2.6 isolates per specimen. The predominant anaerobic organisms were Gram-positive anaerobic cocci, Bacteroides species, and Fusobaeterium species. The predominant aerobic organisms were Staphylococcus aureus, ~t-hemolytic streptococci, Eikenella corrodens, group A p-hemolytic streptococci, R-hemolytic streptococci, and Klebsiella pneumoniae. Candida albicans was recovered in four cases. This study demonstrates the mixed aerobic and anaerobic bacteriology of paronychia. [Brook h Aerobic and anaerobic microbiology of paronychia. Ann Emerg Med September 1990;19:994-996.] INTRODUCTION Paronychia is an infectious process of the structures surrounding the nails that is common in children who suck their fingers or patients who have poor skin hygiene. Bacteriologic studies of paronychia have been reported; u3 however, in most of the studies, techniques for cultivation of anaerobic bacteria were not used. Reports describe the isolation of Staphylococcus aureus, Streptococcus faecalis, coliform organisms, Proteus species, Pseudomonas aeruginosa, and Candida alMcans, 1-3 some of which are part of the normal mouth and anal flora. A recent study in which anaerobic as well as aerobic bacteria were cultivated reported the recovery of anaerobes in 27 of 33 children (73%) with paronychia. 4 The present study was designed to investigate the aerobic and anaerobic bacteriology of paronychia in adults by using methods adequate for the recovery of aerobic and anaerobic bacteria. This information can assist in the management and selection of proper antimicrobial therapy of this infection.
Itzhak Brook, MD, MSc Bethesda, Maryland From the Naval Medical Center, Bethesda, Maryland. Received for publication November 7, 1989. Revision received May 2, 1990. Accepted for publication May 18, 1990. The opinions and assertions contained herein are the private ones of the writer and are not to be construed as official or reflecting the views of the Department of Defense, the Navy Department, or the Naval Service at large. Address for reprints: Itzhak Brook, MD, MSc, Armed Forces Radiobiology Research Institute, Bethesda, Maryland 20814-5145.
PATIENTS A N D METHODS The patients in this study were treated for paronychia of their fingers that required surgical drainage at the National Naval Medical Center in Bethesda, Maryland, between June 1976 and June 1985. During that period, specimens were obtained from 36 patients. Included in the analysis were 28 patients whose specimens yielded bacterial growth. Mean patient age was 30 years (range, 19 to 48 years). Twenty patients were women, and eight were men. Aerobic and anaerobic cultures were obtained from the infected area by aspiration of pus (24) or swabbing the draining wound (nine). Aspirated specimens were transported by a syringe and needle that was capped with a rubber stopper. Swabs were placed into an anaerobic transport media (Port-A-Cul ®, BBL Becton-Dickinson, Cockeysville, Maryland). Within 30 minutes after collection, specimens were transported to the bacteriology laboratory and plated. Sheep blood, chocolate, and MacConkey's agar plates were inoculated for aerobes. The plates were incubated at 37 C aerobically (MacConkey's) or under 5% CO~ and examined at 24 and 48 hours. For anaerobes, the material was plated at the bench
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onto prereduced vitamin Kl-enriched Brucella blood agar, anaerobic blood agar plates c o n t a i n i n g k a n a m y c i n and v a n c o m y c i n , and a n a e r o b i c blood agar containing colistin and nalidixic acid and then placed into enriched thioglycolate broth (containing hemin, sodium bicarbonate, and vitamin K1).,~ The media were incubated in GasPak ® jars (BBL BectonDickinson) and examined at 48 to 96 hours. The thioglycolate broth was used as a backup culture and was incubated for 14 days. Anaerobes were identified by techniques previously described, s Aerobic bacteria were identified by conventional methods. 6 RESULTS In all, 72 isolates were recovered from the 28 specimens, or 2.6 isolates (1.4 anaerobes, 1.2 aerobes, and C albicans) per specimen (Table). Anaerobes only were present in five patients (18%), aerobes only in eight (29%), and mixed aerobes and anaerobes in 15 (54%). Thus, anaerobes were present in 71% of the specimens. No difference was noted in the proportional number of the isolates when the two methods of specimen collection were compared (aspiration with a syringe versus swab). Thirty-nine anaerobic isolates were recovered; in descending order of frequency, they included 19 anaerobic Gram-positive cocci, 15 Bacteroides species (including seven B m e l a n i n o g e n i c u s group), and four Fusobacterium nucleatum. The 29 strains of aerobic or facultative bacteria that were recovered were, in descending order of frequency, eight S aureus, five ~-hemolytic streptococci, three Eikenella corrodens, and two group A ~-hemolytic streptococci. C albicans was recovered in four instances - three times mixed with aerobes, anaerobes, or both. No c o n s i s t e n t pattern of combinations emerged. However, in four of the eight cases in which S aureus was isolated, it was mixed with other aerobic or facultative organisms; in two cases, it was the only organism recovered. DISCUSSION Paronychia is c o m m o n in housewives, cleaners, nurses, and others who often have their hands in water. 2 Children are prone to this infection because of nail biting and finger 82/995
TABLE. Organisms isolated from 28 patients with paronychia Aerobic, Facultative and Candida Isolates (N) Gram-Positive Cocci
Anaerobic Isolates (N)
s-Hemolytic streptococci -y-Hemolytic streptococci Group A i~-hemolytic streptococci Group D streptococci
3 5 2 2 8
Staphylococcus aureus S epidermidis
Gram-Negative Cocci Neisseria species
Eubacterium lentum 2 3
sucking, which predisposes them to paronychia through direct inoculation of the fingers with flora of the mouth, in which anaerobes outnumber aerobes by 10:1. 7 Although no complete history of sucking or biting of fingers was obtained in our study, many of the patients admitted having such habits. This phenomenon is similar to the acquisition of infection after human bites or clenched-fist injuries; studies using techniques for cultivation of anaerobes showed that normal oral flora are the source of most bacterial isolates in infections that develop after these injuries.S, 9 The predominant aerobic isolates were group A streptococci, S aureus, and E corrodens. Anaerobic organisms were recovered in more than half of the patients studied; the m o s t c o m m o n were Bacteroides species, Gram-positive anaerobic cocci, and F n u d e atum.8,9 This study demonstrates the role of anaerobic bacteria in paronychia in adults and illustrates the simAnnals of Emergency Medicine
5 8 I 3 1 1
Gram-Positive Bacilli Gram-Negative Bacilli Klebsiella pneumoniae Eikenella corrodens Acinetobacter species Candida albicans
Peptostreptococcus species P magnus P asaccharolyticus P prevotii P anaerobius Streptococcus intermedius
Fusobacterium nucleatum Bacteroides species B fragilis B melaninogenicus B intermedius B oralis B bivius B oris-buccae
3 2 4 3 1 1 1
ilarity of the microbiology of paronychia in adults to that in children. 4 These organisms were the predominant isolates and outnumbered aerobes. Although S aureus was recovered from 29% of our patients, most had mixed aerobic and anaerobic bacteria recovered from their lesions. The anaerobic organisms isolated (Bacteroides species, Fusobacterium species, and Peptostreptococcus species) are part of normal oropharyngeal flora and may represent self-inoculation of the patient's own mouth flora onto the finger. The results of this study show that the bacteria recovered from paronychia are those that generally colonize the skin and the oral cavity (ie, staphylococci and anaerobes, respectively). It is also evident that paronychia contains polymicrobial aerobic and anaerobic flora, which are known to have a synergistic relationship, m making the infection harder to eradicate. E corrodens, a capnophilic Gramnegative rod that is part of normal 19:9 September 1990
oral flora, ll was isolated from four of our patients. There are more than 67 reported cases in which E corrodens was isolated from h u m a n bite infections.a, 9 This is n o t e w o r t h y because of the u n u s u a l antibiotic sensitivity pattern of E corrodens; it is susceptible to p e n i c i l l i n and a m p i c i l l i n but r e s i s t a n t to o x a c i l l i n , m e t h i c i l l i n , n a f c i l l i n , a n d c l i n d a m y c i n . 12 Alt h o u g h m a n y strains tested against c e p h a l o t h i n are reported to be susceptible, t h e r e are also i s o l a t e s reported to be r e s i s t a n t ) 2 Because anaerobic bacteria play a role i n the e t i o l o g y of p a r o n y c h i a , clinicians should consider their possible presence w h e n selecting antimicrobial therapy. Although m o s t of the a n e r o b e s i s o l a t e d i n our s t u d y (except the Bacteroides fragilis group) are g e n e r a l l y s u s c e p t i b l e to p e n i c i l l i n , g r o w i n g n u m b e r s of B m e l a n i n o g e n i c u s s t r a i n s have b e e n r e p o r t e d to be r e s i s t a n t to t h a t drug. 13 Because most single antimicrobial agents do n o t eradicate-all of the major p a t h o g e n s r e s p o n s i b l e for paronychia, e s t a b l i s h i n g a specific etiologic d i a g n o s i s is u s e f u l to guide therapy. P e n i c i l l i n or a m p i c i l l i n are the m o s t active agents against oral flora organisms. However, S a u r e u s a n d B a c t e r o i d e s species p r e s e n t i n p a r o n y c h i a can be r e s i s t a n t to this drug. Although oxacillin is effective against S aureus, it has poor activity against B a c t e r o i d e s species and m a n y other anaerobic Gram-negative strains. Tetracyclines are good alter-
n a t i v e s b u t s h o u l d n o t be u s e d in y o u n g c h i l d r e n . W h e n S a u r e u s is suspected (based o n the Gram-strain of aspirate, which is specific but not sensitive), penicillin and a peni c i l l i n a s e - r e s i s t a n t p e n i c i l l i n should be used. C l i n d a m y c i n and the c o m b i n a t i o n of a m o x i c i l t i n a n d c l a v u l a n i c acid h a v e a w i d e s p e c t r u m of a c t i v i t y against most pathogens isolated from p a r o n y c h i a . F i r s t - g e n e r a t i o n cephalosporins are not as effective as the above c o m b i n a t i o n due to resistance of some anaerobic bacteria and Esc h e r i c h i a coll.
Most uncomplicated paronychia, w h i c h is w i t h o u t signs of local swelling, o s t e o m y e l i t i s , or e x t e n s i o n of the infection, can be m a n a g e d conservatively. However, w h e n complic a t i o n s o c c u r or t h e i n f e c t i o n spreads, antimicrobial therapy should s u p p l e m e n t surgical drainage. C o n s i d e r i n g the wide v a r i e t y of aerobic a n d a n a e r o b i c b a c t e r i a isolated, it is r e c o m m e n d e d that proper aerobic and anaerobic cultures be obt a i n e d from serious p a r o n y c h i a l infections w h e n antimicrobial therapy is contemplated. Further research is necessary to determine the effectiveness of various antimicrobial agents i n addition to surgical drainage i n the m a n a g e m e n t of paronychia. The author acknowledges the efforts of the Medical and Clinical Microbiology Laboratory staff at the Naval Medical Center and Laura L Garza for her secretarial assistance.
1. BarlowAJ, Chattaway FW, Holgate MC, et al: Chronic paronychia. Br J Dermatol 1970;82: 448~453. 2. FliegelmanMT, Owen LG: How we treat paronychia. Postgrad Med 1970;48:267~268. 3. Chronic paronychia (editorial). Br Med ] 1975;2:460. 4. Brook I: Bacteriologicstudy of paronychia in children. Am J Surg 1981;141:703-705. 5. Sutter VL, Citron DM, EdelsteinMAC, et al: Wadsworth Anaerobic Bacteriology Mammal. ed 4. Belmont, California, Star Publishing Co, 1985. 6. Lennette EH, Balows A, Hausler W, et al: Manual of Clinical Microbiology, ed 4. Washington, DC, American Society for Microbiology, 1985. 7. GibbonsRJ: Aspects of the pathogenicityand ecology of the indigenousoral flora of man, in Ballow A (ed): Anaerobic Bacteria: Role in Disease. Springfield,Illinois, Charles C Thomas, 1974. 8. Goldstein EJC, Citron DM, Wield B, et al: Bacteriology of human and animal bite wounds. J Clin Microbiol 1978;8:667-672. 9. Brook I: Microbiologyof human and animal bite wounds. Pediatr Infect Dis ] 1987;6:29-32. 10. BrookI, Hunter V, Walker RI: Synergisticeffect of Bacteroides, clostridium, Fusobacteria. anaerobic cocci and aerobic bacteria on mortality and induction of subcutaneous abscesses. J Infect Dis 1984;149:924-928. 11. Manson ML, Koch SL: Human bite infections of the hand. Surg Gynecol Obstet 1930;51:591-625. 12. GoldsteinEJC, Sutter VL, FinegoldSM: Sus ceptibility of EJkenella corrodens to ten cephalosporins. Antimicrob Agents Chernother 1978;14:639-641. 13. Brook I, Calhoun L, Yocum P: Beta lactamase-producing isolates of Bacteroides species from children. Antimicrob Agents Chemother 1980;18:164-166. Q
See related editorial, p 1069.
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