Aeromonas bacteraemia in burn patients

ELSEVIER

D. J. Barillo, A. T. McManus,

W. G. Cioffi, W. F. McManus,

US Army Institute of Surgical Research, Fort Sam Houston,

Human aeromonas infection is uncommon and is usually associated with immunosuppression, chronic disease OY trauma in an aquatic setting. Buminjury may induce a state of immunosuppression, making the fhewnally injured patient a suitable host for aeromonas infecfion. We reviewed the experience of one burn cenfre with this pathogen. Retrospective examinafion of blood culture results from 8751 patients admitted between 1959 and 1994 disclosed eight patienfs with clinically relevanf Aeromonas hydrophilia bacteraemia. Five were burned outside the USA. Aquatic exposure wasknown OY suspected in only three cases,Five of the eight patients died. Aeromonas infection in burn patients is rare but may OCCUY in the absenke Ifaquafic exposure.

Burns,Vol. 22,

No.

1, 48-52,

1996

Introduction Aeromonas speciesare motile Gram-negative non-sporeforming rods with facultative anaerobic metabolism1-5. This bacterial genus is normally found in fresh and brackish water, soil and non-faecal organic matter1-3’6,7.Aeromonas infections most often occur in fish, amphibiansand aquatic reptiles1-3,7,8.Human infection is rare, and most often associatedwith either traumatic injuries contaminated with water or soil, or with immunosuppression.The aeromonas speciesmost often responsible for human infection is A. hydrophilu?.

Infection of burned patients by aeromonas speciesis ‘extremely rare’9, with lessthan ten reported casesin the English language literature. Our recent experience with invasive wound infection and bacteremia due to A. hydrophilia in a bum patient has prompted this review of our institutional experience-with this pathogen. We herein report eight patients with A. hydrophilia infection that have occurred during the treatment of more than 8150 bum patients admitted to one burn centre.

“Presented at the Ninth Congress of the International Society for Bum Injuries, Paris, France, June 1994. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.

S. H. Kim and B. A. Pruitt Jr

Texas, USA

Materials

and methods

Microbiology records of patients admitted to the Institute of Surgical Research(ISR) between 1959 and 1994 were reviewed for blood cultures positive for aeromonas species.Individual patient charts were then reviewed for clinical correlation; data abstracted included mechanismof injury, size of bum, hospital course and patient outcome.

Results Eight patients with Aeromonas hydrophilia bacteraemia were identified (TableI). Five of the eight were burned outside the continental USA. All were hospitalized in other facilities prior to transfer and arrived at the ISR on average 4.5 days after their injuries. No cases of aeromonas bacteraemia were diagnosed in patients admitted directly to this facility. Representative casesare presented below.

Case reports A 33.year-oldpreviously healthy male sustained an 80 per cent total body surface area (TBSA) 47 per cent Ml-thickness burn in a tuna

cannery

explosion

in Mexico. He was sprayedwith hot

water and debris when a cooking tank exploded. in

He was treated

Mexico for the first 48 h postbum,and then transferredto a

burn centre in California where upper extremity escharotomies were performed on admission. Bum wound biopsies were reported as histologically negative for infection. The patient was transferred to the ISR on postbum day 4. Debris from the explosion was noted to be deeply embedded in his back and left flank (Figure I) and wound biopsy confirmed colonization with Gram-negative bacilli, graded by the pathologist as stage IB (Table 1I). Biopsy cultures grew Pseudomonas aeruginosa and Klebsiella pneumonia. HIV-1 serology was negative. The left tlank was excised and autografted on postburn day 7. Uperative specimens demonstrated acute inflammatory cell infiltration and foci of Gram-negative bacilli without evidence of invasion. The patient became glucose intolerant and blood cultures drawn on postbum days 8 and 9 were positive for A. hydrophilia, sensitive to amikacin and piperacillin. Antibiotic therapy was instituted. Bum wound biopsies were repeated, and demonstrated dense Gram-negative colonization of the right flank at the viable/nonviable tissue interface (stage IC), superficial Gram-negative coionization (stageIA) of the right sideof the back,andinvasive infection (level 2A) of the lower back (Figurz~). Subeschar clysiP with piperacillin was performed six times over the next

Barillo

et al.: Aeromonas

Table I. Aeromonas

bacteraemia

in burn patients

49

bacteraemia in ISR bum patients Bum size A. hydrophilia

Case

(yr)

Sex

Total (%)

Third (96)”

History

1' 2

33 31

M M

80 38

47 35

3

23

M

58

46

4

22

M

54

44

5’

20

F

76

41

6’

68

F

55

40

7’

27

M

56

55

8’

39

M

55

47

Explosion in tuna cannery in Mexico Motor vehicle crash and fire in Alabama with possible river water contact Fuel truck crash and fire in Turkey, no known aquatic contact Clothing ignition from cigarette in Japan, possible contact with river water House fire in North Carolina, no known aquatic contact Burned in New Mexico attempting to light kerosene heater: delay in medical treatment. No known aquatic exposure Self-immolation with flammable liquid in Korea. No known aquatic exposure Plane crash and fire in Mexico, no known aquatic exposure

‘Full skin thickness ‘Patient died.

Blood Blood

x 5; sputum x2

cultures

x 5; wound

biopsy

x 2

Blood, intraoperative culture of necrotic muscle Blood x 2; line tip; wound surface culture Blood

x 2; burn surface

cultures

x 2

Blood

Blood

x 4; chest tube drainage

Blood;

line tip; burn surface

cultures

x 5

area

48 h. Wound biopsy following clysis demonstrated superficial Gram-negative colonization (stage 1A) in the left leg, with no organisms seen in specimens from the back, arms and right leg. Operative debridement was attempted but unsuccessful secondary to haemodynamic instability on induction of anaesthesia. The patient developed multiple organ failure and died on postbum day 17. Autopsy demonstrated haemorrhage and infarction of the adrenal glands, interstitial nephritis, focal acufe myocardial infarction, and necrotizing tracheobronchitis. No Gram-negative organisms were found on histological examination of the bum wounds.

Figure 1. Admission photograph embedded debris in wound.

Table II. Histological

Stage

1B

Stage

1C

Invasion Stage 2A Stage 2B Stage

2C

1

demonstrating

classification of bum wound

Histological Colonization Stage 1 A

of patient

evidence

of microbial

infection growth

Sparse microbial population on burn wound surface Microorganisms present in variable thickness of eschar Dense population of microorganisms at viable/ non-viable tissue interface

Microscopic immediately Widespread into viable Involvement

foci of microorganisms in viable tissue subjacent to subeschar space penetration of microorganisms deep subcutaneous tissues of lymphatics and microvasculature

Case 2 A 31-year-old male sustained a 38 per cent TBSA, 35 per cent full-thickness bum as the unrestrained driver of a pick-up truck that struck a bridge and caught fire in Alabama. It was reported but not confirmed that his wounds were contaminated with river water at the time of injury. Following extrication, he was transferred fo a regional bum facility, where he underwent left upper extremity escharotomy and routine resuscitation. Stuphylococcus hominis pneumonia was diagnosed and treated with intravenous vancomycin therapy. On postbum day 7, blood cultures were positive for A. hydrophilia, and intravenous amikacin and piperacillin were initiated. He was transferred to the ISR on postbum day 11. Admission blood cultures grew A. hydrophilic and vancomycin, amikacin and piperacillin were continued. HIV-1 serology was negative. Blood cultures following treatment remained negative and he was discharged following grafting and reconstructive procedures. Case 3 A 23-year-old male soldier sustained a 58 per cent TBSA 46 per cent full-thickness bum in a fuel truck crash in Turkey. Initial treatment included chest escharotomy and combined escharotomy/fasciotomy of the upper extremities. He arrived at the ISR on postburn day 5 with burn wound cellulitis present. Blood cultures on admission and intravenous catheter tip culture the following day grew A. hydrophiliu. Wound biopsies demonstrated Gram-negative colonization of the eschar (stage IB), but culture of the biopsy specimen produced no growth. Intravenous

Burns: Vol. 22, No. 1, 1996

50 therapy with vancomycin and amikacin were initiated for cellulitis; nevertheless, the patient remained febrile. A search for a septic focus, including daily blood cultures, was unrevealing. Burns of the chest and arms were excised and covered with allograft on postburn day 6 and the bums of the legs were excised to fascia on postbum day 13. At that time, necrosisof muscle in the anterior compartment of the left leg was noted

Figure 2. Invasive aeromonas bum wound infection.

Figure 3. Aeromonas patient 3.

infection and necrotic muscle from leg of

(Figure3). Cultures of the necrotic muscle grew A. h+4qMjil, Following debridement, the patient defervesced and had a:~ uneventful hospital course.

Discussion Human aeromonas infection is uncommon. Although aeromonaswas first recovered from the human CI tract ir! 1937, opportunistic human infection was not described until 196S2,’and reports of infection in imtiunocompetent individuals did not appear until the following deca&3AlL’2 Aeromonas infection is a reportable disease in California, where the reported wound infection rate is 0.7 per I million population’,7. Human aeromonas infection may present as acute gastroenteritis, cellulitis or wound infection, isolated bacteraemia, or bacteraemia combined with a local infectionz,13.Gastroenteritis is the most common presmtation4 and is usually self-limited”. Aeromonas is not a part oi normal human faecal flora’.14, but is occasionally cultured from the gut of asymptomatic individualsX5. Cellulitis or wound infection due to aeromonasspecies usually involves traumatic injury in an aquatic environ ments,13,16-18 or wound contamination with soil,‘,“. Aeromonasinfection hasresulted from alligator bites”“, catfishspine puncture woundP, motor vehicle crashes when open fractures contacted stagnant or rain water’2.2L and following simplelacerations or abrasionsin lakes,ponds or rivers7~13~‘4~17~22. The use of lake water asan extinguishing agent has been iinked to aeromonas infection in burn patientsgfZ3.Aeromonas has been recovered horn hospital water supplies”3,and nosocomial infectiori hasbeen linked to tap water usedto clean lacerations or frostbite injury4.z4. Soft-tissue infection has a rapid onset, usually within 24-48 h of injury, Subcutaneous abscessformation is common and may not be clinically apparent. Infection is frequently polymicrobial and may be accompanied by a foul odour1,4,13.Aeromonas infection nay mimic pseudomonas infection to the point of ecthyma gangrenosum formation3,9, or may produce gas in so&-tidu~ planes, similar to the pattern seen in clostridial infection4’“5. Aeromonas is especially destructive of muscle3’21, and necrotizing myonecrosis resulting in amputation or death can develop from local infection or from haemotogenous spread of aeromonas bacteria in otherwise healthi;

Table III. Reported cases of aeromonas bum infection Burn

size -

Study

Age (yr)

Third

Sex

Total (%)

(%I

History

l

Purdue

and Hunt

19889

21

M

82

53

MVA,

Purdue

and

19889’

20

M

45

39

Purdue

and Hunt

19888

17

M

59

Not listed

Peter 1 981z3

70

M

40

MVA, fire, extinguished with lake water Gasoline fire, extinguished by rolling in dirt Fire in boathouse, jumped into pond

NA 29

NA F

Ampel

and

Hunt

Rosenthal et al. 1974’$ Smith 1 9803’ ‘Full skin thickness area. ‘Patient died. MVA= motor vehicle accident;

0

‘Second degree’ Right hand 0

PBD = postburn

day

Small Scald

fire, rolled

in ditch

second degree burn burn, not ciinically infected

A. hydrophllia

-..

cultures

-.----~-.-.

--

A. hydrophitia: arm swab PBD2, operative specimens PBD 4 A. hydrophilta: wound biopsy and blood culture A hydrophitia: ‘heavy’ surface culture and operative specimen PBD 2 A. hydrophilia: skin PBD 2, 3 blood cultures on PBD 4 A. hydrophilia: site not mentioned Blister fluid: A. hydrophitia and f. cnli

Barillo

et al.: Aeromonas

bacteraemia

51

in burn patients

individuals3~Z5-27. Myonecrosis or septic shock from aeromonasinfection may alsodevelop from the therapeutic use of leeches(Himdo medicinalis)in reconstructive surgery, as A. kydropkilia is a normal inhabitant of the leech foregut and is necessary for the digestion of bloodZ,Zp-31.For this reason antibiotic coverage for aeromonas should be provided whenever medicinal leeches are utilizedZ8,Z9.Burn wound infection with aeromonas is distinctly unusual (Table111).Purdue and Hunt9 documented three aeromonas bum wound infections including case of aeromonasbacteraemia in 2400 consecutive admissions to one bum centre. Rosenthal et a1.19reported one aeromonas‘infection’ in a partial-thickness bum. The site of the positive culture was not noted. Ampel and Peter treated a burn patient who developed A. kydropkilia septicaemiafollowing a boathouse firez3. Smith3” reported one patient with asymptomatic aeromonascolonization of bum blister fluid. Treatment of aeromonaswound infection should combine medical and surgical therapy, although surgical treatment alone hasresolved infection in caseswhere no or inappropriate antibiotics were used’~‘,**. Empirical antibiotic therapy is frequently ineffective”“, as the clinical syndrome often mimics staphylococcal or streptococcal infection”, and most antibiotics selected on this basiswill not be an adequate form of treatment for aeromonas species.The formation of gas within soft tissuemay further cloud the issue if a presumptive diagnosis of clostridial infection is made radiographically4,25.Aeromonas species elaborate beta lactamase14,and are usually resistant to penicillinl.3,6,13’6, first-generation cephalosporins’*‘3”4,26, ampicillin5~6~‘3~‘4, carbenicillin1,‘3, vancomycin and clindamycin”. Antibiotics consistently effective against aeromonas species include the aminoglycosides, dotrimethoprim-sulpharamphenicol, tetracyclines, methoxasole, imipenem, aztreonam, ciprofloxacin and particularly cephalosporins, third-generation cefotaxime’~l4~16~20.26’30’33

Aeromonas is an uncommon human pathogen and a very rare causeof infection in bum patients. Nevertheless, aeromonasinfection may occur in the absenceof known aquatic exposure, may produce invasive infection of bum wounds, and may mimic the infectious processescausedby more common pathogens such as clostridia, staphylococcus, streptococcus or pseudomonasspecies.Therapy aimed at these pathogens may be ineffective against aeromonas,and failure of responseto such therapy should prompt consideration of aeromonas as the offending species.

5 ReinesHD, Cook FV. Pneumoniaand bacteremiadue to Aeromonas hydrophila. Chest 1981;80: 264-267. 6 Golik A, Leonov Y, Schlaeffer F et al. Aeromonas species bacteremia in nonimmunocompromised reports and a review of the literature.

hosts - two case lsrael] Med Sci 1990;

26:87-90. 7 Werner SB. Aeromonas wound infections associated with outdoor activities-California. MMWR 1990; 39: 334-341. 8 Fulghum DD, Linton WR, Taplin D. Fatal Aeromonas hydrophilia infection of the skin. Soufhern Med J 1978; 71:

739-741. 9 Purdue GF, Hunt JL. Aeromonas hydrophilia infection in burn patients.Burns 1988;14:220-221. 10 McManus WF, Goodwin CW, Mason AD et al. Burn wound infection. ] Trauma 1981;21: 753. 11 Joseph SW, Daily OP, Hunt et al. Aeromonas primary wound infection of a diver in polluted waters. ] C/in Microbial

1979;10:46-49. 12 Blatz DJ. Open fractures of the tibia and fibula complicated by infection with Aeromonas hydrophilia. 1 Bone Joint Surg

1979;61A:790-791. 13 Semel JD, Trenholme G. Aeromonas hydrophilia waterassociated traumatic wound infections; a review. ] Trauma

1990;30:324-327. 14 Karam GH, Ackley AM, Dismukes WE. Postraumatic Aeromonas hydrophilia osteomyelitis. Arch Intern Med 1983; 14:

2073-2074. 15 Millership SE, Curnow SR, Chattopadhyay B. Faecal carriage rate of Aeromonashydrophilia. J Clin Pafhol 1983; 36:

920-923. 16 Young DF, Barr RJ. Aeromonas hydrophilia infection skin. Arch Dewnafol 1981;117: 244.

of the

17 Hanson PG, Standridge J, Jarrett F, Maki DG. Freshwater infection due to Aeromonas hydrophilia. ]AMA 1977; 283:

1053-1054. 18 Bateman JL, Tu RP, Strampfer MJ, Cunha BA. Aeromonas hydropkilia cellulitis and wound infections caused by waterborne organisms. Heart Lung 1988; 17: 99-102. 19 Rosenthal SG, Bemhardt HE, Phillips JA. Aeromonas hydrophilia wound infection. Plasf Reconsfr Surg 1974; 53: 77-79. 20 Murphey DK Septimus EJ, Waagner DC. Catfish-related injury and infection: report of two cases and review of the literature. Clin Infect Dis 1992;14: 689-693. 21 Deepe GS, Coonrod JD. Fulminant wound infection with Aeromonas hydrophilia. Southern Med J 1980;73: 1546-1547. 22 Skiendzielewski JJ,O’Keefe KP. Wound infection due to fresh water contamination by Aeromonas hydrophilia. / Emerg Med

1990;8:701-703. 23 Ampel N, Peter G. Aeromonas bacteraemia in a bum patient. Lancef 1981; 31: 987 (letter). WR, Hodges GR et al. Nosocomial Aeromonas hydrophilia cellulitis and bacteremia in a nonimmunocompromised patient. Southern Med ] 1981; 74:

24 Lynch JM, Tilson

References I Gold WL, Salit IE. Aeromonas hydrophila infectionsof skin and soft tissue:report of I 1 casesand review. CIin Infect Dis 1993;16:69-74. 2 McGowan JE, Del Rio C. Other gram negative bacilli. In: Mandell GL, DouglasRG, Bennett JE (eds) Principles and Pracfice of Infectious Diseases, 3rd ed. New York: Churchill Livingstone,1990. 3 Davis WA, Kane JG, Garagusi VF. Human aeromonas infections; a review of the literature and a case report of endocarditis Medicine 1978;57: 267-277. 4 Geller HS, Tofte RW, Cunningham BL. Aeromonas hydrophilia wound infection of the hand initially presenting as clostridial myonecrosis. J Hand Swg 1983; 8: 333-335.

901-902. 25 Heckerling PS, Stine TM, Pottage et al. Aeromonas hydrophilia myonecrosis and gas gangrene in a noncompromised host. Arch InfemMed 1983;143:2005-2007. 26 Lineaweaver WC, Follansbee S, Hing DN. CefotaximesensitiveAermonas hydrophilia infection in a revascularized foot. Ann PlasfSurg1988;20: 322-325. 27 Siddiqui MN, Ahmed I, Farooqi BJ et al. Myonecrosis due to Aeromonas hydrophilia following insertion of an intravenous cannula: case report and review: Comm Infecf Dis 1992;

619-620. 28 Lineaweaver

WC, Fumas H, Follansbee S et al. Postprandial Aeromonas hydrophila cultures and antibiotic levels of enteric

52

Burns: Vol. 22, No. 1, 1996

aspirates from medicinal leeches applied to patients receiving antibiotics. Ann Pht Surg 1992; 29: 245-249. 29 Lineaweaver WC, Hill MK, Bunke GM et al. Aeromanas hydrophilic infections following use of medicinal leeches in replantation and flap surgery. Ann Plast Surg 1992; 29: 238-244. 30 Dickson WA, Boothman P, Hare K. An unusual source of hospital wound infection. BY Med ] 1984; 289: 1727-1728. 31 Snower DP, Ruef C, Kuritza AP et al. Aeromonm hydrophilia infection associated with the use of medicinal leeches. J Clin

Micrabid 1989;

27:

1421-1422.

32 Smith JA. Aeromonas.hydrophilia: analysrs of 11 cases. CUTE Med Assoc] 1980; 122: 1270-1272. 33 Christou NV, Solomkin JS. Antibiotics. in. ‘Wilmore D ieti: American College of Surgeons Care of fhe Sqeic~r/ Ptifiet~f WI t New York: Scientific American Medicine, I 993 Paper accepted

15 May

1995

-Correspondence should be addressed to: Dr D J. harilio, Ft Sam Houston, TX 78234, USA.

USAISR