JOURNAL OF CLINICAL MICROBIOLOGY, Nov. 1990, p. 2559-2560
Vol. 28, No. 11
0095-1137/90/112559-02$02.00/0 Copyright © 1990, American Society for Microbiology
NOTES Interpretation of Gram-Stained Sputa Containing Moraxella (Branhamella) catarrhalis SAMUEL M. AINSWORTH,'* STEPHANIE B. NAGY,' LORETTA A. MORGAN,' GLENDON R. MILLER,2 AND JACK L. PERRY3 Department of Biological Sciences, The Wichita State University, Wichita, Kansas 672082; Laboratory Service, Department of Veterans Affairs, Wichita, Kansas 672183; and Laboratory Service, Department of Veterans Affairs, Alexandria, Louisiana 713011 Received 4 June 1990/Accepted 30 July 1990
Sputum specimens culture positive for Moraxella (Branhamella) catarrhalis were Gram stained with three decolorizer solutions (slow, 95% ethyl alcohol; intermediate, 1:1 ratio of 95% ethyl alcohol and acetone; and fast, acetone alone) for 5, 10, 20, and 30 s. Optimal results were obtained with acetone alone after 10 s or with a 1:1 mixture of acetone and ethanol after 20 s. Inadequate decolorization of M. catarrhalis in sputa is likely if the decolorization solution and exposure time are not optimal and may contribute to underreporting of this organism.
Moraxella (Branhamella) catarrhalis has received increasing attention as an important emerging pathogen of both the upper and lower respiratory tracts (2, 4, 5, 16, 18). The majority of clinical isolates produce ,-lactamases (12, 17) and are refractory to therapy with many antimicrobial agents. Accordingly, clinical laboratories have developed increased awareness of this organism and commercial systems for rapid, accurate identification of M. catarrhalis have proliferated (7, 9-11, 14). M. catarrhalis is sometimes overlooked as one of several organisms commonly isolated from expectorated sputa, and unless culture processing is guided by correct Gram stain interpretations, the incidence of this organism can be underreported. Although the presence of large numbers of a specific morphologic bacterial type coupled with abundant polymorphonuclear neutrophils in Gram-stained sputa suggests an infectious process, convincing data are lacking and conclusions remain controversial. Large numbers of intraand extracellular gram-negative diplococci present in a Gram-stained preparation of expectorated sputa suggest Neisseria or Moraxella spp., can be considered pathognomonic for M. catarrhalis (3), and indicate that the microbiologist should carefully review resulting bacterial growth (1, 8, 15). Unfortunately, Gram stain findings are not uniformly accurate with these organism groups. A recent report detailed two cases of neisserial infection in dialysis patients in which Gram-stained smears of bacterial growth revealed gram-positive cocci (J. R. Shooter, M. J. Howles, and V. S. Baselski, Clin. Microbiol. Newsl. 12:1516, 1990). Similar resistance to decolorization has been reported for Moraxella spp. (13). We evaluated 792 sputum specimens for the presence of M. catarrhalis by using routine culture methods, an experimental selective medium, and Gram staining. Specimens processed were designated group 1 sputa (>25 neutrophils and
Vol. 28, No. 11
0095-1137/90/112559-02$02.00/0 Copyright © 1990, American Society for Microbiology
NOTES Interpretation of Gram-Stained Sputa Containing Moraxella (Branhamella) catarrhalis SAMUEL M. AINSWORTH,'* STEPHANIE B. NAGY,' LORETTA A. MORGAN,' GLENDON R. MILLER,2 AND JACK L. PERRY3 Department of Biological Sciences, The Wichita State University, Wichita, Kansas 672082; Laboratory Service, Department of Veterans Affairs, Wichita, Kansas 672183; and Laboratory Service, Department of Veterans Affairs, Alexandria, Louisiana 713011 Received 4 June 1990/Accepted 30 July 1990
Sputum specimens culture positive for Moraxella (Branhamella) catarrhalis were Gram stained with three decolorizer solutions (slow, 95% ethyl alcohol; intermediate, 1:1 ratio of 95% ethyl alcohol and acetone; and fast, acetone alone) for 5, 10, 20, and 30 s. Optimal results were obtained with acetone alone after 10 s or with a 1:1 mixture of acetone and ethanol after 20 s. Inadequate decolorization of M. catarrhalis in sputa is likely if the decolorization solution and exposure time are not optimal and may contribute to underreporting of this organism.
Moraxella (Branhamella) catarrhalis has received increasing attention as an important emerging pathogen of both the upper and lower respiratory tracts (2, 4, 5, 16, 18). The majority of clinical isolates produce ,-lactamases (12, 17) and are refractory to therapy with many antimicrobial agents. Accordingly, clinical laboratories have developed increased awareness of this organism and commercial systems for rapid, accurate identification of M. catarrhalis have proliferated (7, 9-11, 14). M. catarrhalis is sometimes overlooked as one of several organisms commonly isolated from expectorated sputa, and unless culture processing is guided by correct Gram stain interpretations, the incidence of this organism can be underreported. Although the presence of large numbers of a specific morphologic bacterial type coupled with abundant polymorphonuclear neutrophils in Gram-stained sputa suggests an infectious process, convincing data are lacking and conclusions remain controversial. Large numbers of intraand extracellular gram-negative diplococci present in a Gram-stained preparation of expectorated sputa suggest Neisseria or Moraxella spp., can be considered pathognomonic for M. catarrhalis (3), and indicate that the microbiologist should carefully review resulting bacterial growth (1, 8, 15). Unfortunately, Gram stain findings are not uniformly accurate with these organism groups. A recent report detailed two cases of neisserial infection in dialysis patients in which Gram-stained smears of bacterial growth revealed gram-positive cocci (J. R. Shooter, M. J. Howles, and V. S. Baselski, Clin. Microbiol. Newsl. 12:1516, 1990). Similar resistance to decolorization has been reported for Moraxella spp. (13). We evaluated 792 sputum specimens for the presence of M. catarrhalis by using routine culture methods, an experimental selective medium, and Gram staining. Specimens processed were designated group 1 sputa (>25 neutrophils and
