Characterization of the Morphologic Conversion ofHelicobacter pylorifrom Bacillary to Coccoid Forms

Abstract

Catrenich CE, Makin KM. Characterization of the morphologic conversion of Helicobacter pylori from bacillary to coccoid forms. Scand J Gastroenterol1991,26(suppl 181), 58-64Growth studies of Helicobacter pylori were performed involving analysis of the bacterium and its microenvironment, to lend insight into the factors responsible for the morphologic conversion phenomenon. H . pylori converted from bacillary to coccoid forms in broth culture after incubation for 5 days under microaerobic conditions with agitation. This morphologic conversion was paralleled by a dramatic decrease in colony-forming units per milliliter (CFU/ml) and a significant endogenous increase in the pH of the broth culture. In addition, removal of broth cultures from microaerobic conditions after 3 days of incubation resulted in a rapid increase in culture pH, a morphologic conversion, and a concomitant decrease of CFU/ml. These observations suggest an inhibitory effect of basic pH, endogenously produced, on the growth of H. pylori in vitro. Experiments designed to identify the reason for the endogenous increase in culture pH demonstrated that the urease enzyme of H. pylori is not primarily responsible for this phenomenon. Rather, H. pylori appears to produce a deaminase enzyme that is likely responsible for the generation of ammonia, which results in the increase in culture pH. the morphologic conversion, and the loss of culturability observed in vitro. Also indicated is the need for a buffering component (for example, bicarbonate) to maintain pH conditions favorable to the growth of H. pylori.Scand J Gastroenterol Downloaded from informahealthcare.com by Thomas Jefferson University on 03/11/15For personal use only.Scand J Gastroenterol Downloaded from informahealthcare.com by Thomas Jefferson University on 03/11/15For personal use only.

Characteristics of Helicobacter pylori growth in a defined medium and determination of its amino acid requirements

“…This is typical for other media studied, e.g. Mueller-Hinton broth (Sorberg e t al., 1993) and Brucella broth (Catrenich & Makin, 1991 ; Cellini e t al., 1993). However, a major difference was that in the defined medium the rate of death in the death phase was lower and the conversion to the coccoid form reduced from 99 % to just 50 %.…”

Interleukin-8 induction and adhesion of the coccoid form of Helicobacter pylori

“…Helicobacter pylori changes its morphology in vitro from a helical form to a coccoid form under various conditions such as extended cultivation [1,2], aerobic culture [3], alkaline pH [3] and antibiotic treatment [4,5]. In the human stomach, the ability of the helical form of the micro-organism to colonise gastric mucosa and to attach to mucosal epithelial cells has been well documented.…”

The relationship between Helicobacter pylori motility, morphology and phase of growth: implications for gastric colonization and pathology

“…There have, however, been reports of apparently non-motile H. pylori with Ushaped, doughnut-shaped (precoccoidal ; Benaissa et al, 1996) and coccoidal (Buck et al, 1986 ;Chan et al, 1994 ;Janas et al, 1995 ;Megraud, 1989 ;Moshkowitz et al, 1994 ;Noach et al, 1994) morphologies. H. pylori with these atypical structures is seen occasionally in vivo (Caselli et al, 1993 ;Chan et al, 1994 ;Janas et al, 1995 ;Noach et al, 1994), but most frequently in vitro in old cultures (Andersen et al, 1997 ;Catrenich & Makin, 1991 ;Cellini et al, 1994 ;Jones & Curry, 1990 ;Kusters et al, 1997 ;Mai et al, 1989 ;Moshkowitz et al, 1994 ;Nilius et al, 1993). It remains uncertain whether coccoidal forms are degenerative (Buck et al, 1986 ;Catrenich & Makin, 1991 ;Cellini et al, 1994 ;Kusters et al, 1997 ;Nilius et al, 1993), or adaptations to marginal or hostile environments (Janas et al, 1995), with a capacity for transmission and regrowth to the bacillary form (Andersen et al, 1997 ;Benaissa et al, 1996 ;Bode et al, 1991 ;Jones & Curry, 1990 ;Mai et al, 1989).…”