Correspondence

Acinetobacter Infection

N Engl J Med 2008; 358:2845-2847June 26, 2008

Article

To the Editor:

In their review article, Munoz-Price and Weinstein (March 20 issue)1 state that “Acinetobacter is a gram-negative coccobacillus” and that it is “nonreactive in many biochemical tests commonly used to differentiate among gram-negative bacilli.” However, acinetobacter can be gram-variable and even gram-positive on initial Gram's staining.2,3 The appearance of the bacteria is highly dependent on its life-cycle phase: it is rod-shaped during the growth phase and coccobacillary during the stationary phase.4,5 The oxidase-negative characteristic allows one to differentiate acinetobacter from other important gram-negative bacteria such as pseudomonas and neisseria.4,5 This information can be useful with respect to diagnosis and time to treatment when a clinician has a high clinical suspicion of acinetobacter infection but the Gram's stain does not show a gram-negative coccobacillus.

Roger Kapoor, M.D., M.B.A.
Stanford University, Palo Alto, CA 94305
rkapoor1@stanford.edu

5 References

1. 1

   Munoz-Price LS, Weinstein RA. Acinetobacter infection. N Engl J Med 2008;358:1271-1281
   Full Text | Web of Science | Medline

2. 2

   Goodhart GL, Abrutyn E, Watson R, Root RK, Egert J. Community-acquired Acinetobacter calcoaceticus var anitratus pneumonia. JAMA 1977;238:1516-1518
   CrossRef | Web of Science | Medline

3. 3

   Mason DJ, Shanmuganathan S, Mortimer FC, Gant VA. A fluorescent Gram stain for flow cytometry and epifluorescence microscopy. Appl Environ Microbiol 1998;64:2681-2685
   Web of Science | Medline

4. 4

   Mandell GL, Bennett JE, Dolin R, eds. Principles and practices of infectious diseases. 6th ed. Philadelphia: Churchill Livingstone, 2005:2632-6.
   

5. 5

   Koneman EW, Schreckenberger PC, Allen SD, Winn WC, Janda WM. Color atlas and textbook of diagnostic microbiology. Philadelphia: Lippincott, 1997:253-309.
   

To the Editor:

Munoz-Price and Weinstein did not comment on abscesses as one of the clinical manifestations of acinetobacter infection. In our intensive care unit (ICU), we identified two patients with multidrug-resistant Acinetobacter baumannii abscesses. The first patient was a 77-year-old woman who underwent splenectomy after multiple trauma and in whom a lung abscess developed after 60 days in the ICU. This patient recovered. In the literature there is a case report of a lung abscess1 and three cases of pneumatoceles due to A. baumannii.2 The second patient was a 68-year-old man who also underwent splenectomy after multiple trauma, and in whom an intraabdominal abscess developed at the site of splenectomy 10 days after admission to the ICU. This patient died. To our knowledge, only four cases of A. baumannii intraabdominal abscesses have been reported in the literature.3,4

Pavlos Myrianthefs, M.D., Ph.D.
Athens University School of Nursing, 14561 Athens, Greece
pmiriant@nurs.uoa.gr

Alexandra Gavala, M.D.
Kentro Atiximation Hospital, 15122 Athens, Greece

George Baltopoulos, M.D., Ph.D.
Athens University School of Nursing, 14561 Athens, Greece

4 References

1. 1

   Yen CC, Tang RB, Chen SJ, Chin TW. Pediatric lung abscess: a retrospective review of 23 cases. J Microbiol Immunol Infect 2004;37:45-49
   Medline

2. 2

   Hunt JP, Buechter KJ, Fakhry SM. Acinetobacter calcoaceticus pneumonia and the formation of pneumatoceles. J Trauma 2000;48:964-970
   CrossRef | Web of Science | Medline

3. 3

   Goh BK, Alkouder G, Lama TK, Tan CE. Multi-drug-resistant Acinetobacter baumannii intra-abdominal abscess. Surg Infect (Larchmt) 2005;6:345-347
   CrossRef | Medline

4. 4

   Trottier V, Namias N, Pust DG, et al. Outcomes of Acinetobacter baumannii infection in critically ill surgical patients. Surg Infect (Larchmt) 2007;8:437-443
   CrossRef | Medline

To the Editor:

As pointed out by Munoz-Price and Weinstein, A. baumannii is an important contaminant of wounds, and it is an important causative agent of infectious complications of open fractures, as reported in studies involving combat casualties.1-3 In our reference service in Brazil for severe skeletal trauma, over the past 5 years A. baumannii was the second most frequent agent related to infection in open Gustilo type II and III fractures. It was isolated in 25 patients (18% of the total number of patients), and the majority of isolates were multidrug-resistant.

Ana L. Lima, M.D., Ph.D.
Priscila R. Oliveira, M.D.
Adriana P. Paula, R.N.
University of São Paulo, 05403-010 São Paulo, Brazil
ccih.iot@hcnet.usp.br

3 References

1. 1

   Johnson EN, Burns TC, Hayda RA, Hospenthal DR, Murray CK. Infectious complications of open type III tibial fractures among combat casualties. Clin Infect Dis 2007;45:409-415
   CrossRef | Web of Science | Medline

2. 2

   Davis KA, Moran KA, McAllister CK, Gray PJ. Multidrug-resistant Acinetobacter extremity infections in soldiers. Emerg Infect Dis 2005;11:1218-1224
   Web of Science | Medline

3. 3

   Petersen K, Riddle MS, Danko JR, et al. Trauma-related infections in battlefield casualties from Iraq. Ann Surg 2007;245:803-811
   CrossRef | Web of Science | Medline

Author/Editor Response

Kapoor is correct. As noted in our review article, on Gram's staining of cultures of acinetobacter, bacilli or coccobacilli may predominate, depending on the culture medium. Young acinetobacter cultures (most frequently in liquid mediums) can stain as gram-positive1 and have coccal morphology for approximately 24 hours; the latter effect is seen in up to 25% of liquid cultures growing acinetobacter (Schreckenberger P: personal communication). This behavior is shared by other gram-negative bacilli such as neisseria and moraxella. Regarding the oxidase-negative characteristic, it is true that it will differentiate acinetobacter from oxidase-positive organisms such as pseudomonas and neisseria; however, it will not differentiate acinetobacter from oxidase-negative nonfermenting bacteria such as Stenotrophomonas maltophilia or oxidase-negative fermenting bacteria such as members of the Enterobacteriaceae family.

As mentioned by Myrianthefs et al. and Lima et al., acinetobacter can manifest as wound infections. As we noted, in one series of patients affected by a natural disaster, 20% of wounds were infected with acinetobacter; acinetobacter was also a common cause of infected wounds in the battlefield and burn injuries. Our experience in the greater Chicago area is that acinetobacter detected in wounds more frequently tends to be a contaminant than an actual pathogen. Nevertheless, in the majority of settings, the most common presentations are respiratory, urinary, and blood infections.

L. Silvia Munoz-Price, M.D.
Medical Specialists, Munster, IN 46321
simunozprice@gmail.com

Robert A. Weinstein, M.D.
Stroger (Cook County) Hospital, Chicago, IL 60612

1 References

1. 1

   Murray PR, Baron EJ, Jorgensen JH, Landry ML, Pfaller MA, eds. Manual of clinical microbiology. 9th ed. Washington, DC: ASM Press, 2007:770-802.