BACTERIOLOGICAL SURVEY OF LEGIONELLA SPECIES IN THE NORTHERN STATES OF NIGERIA
BACTERIOLOGICAL SURVEY OF LEGIONELLA SPECIES IN THE NORTHERN STATES OF NIGERIA
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Date
1998-02
Authors
YAKUBU, SABO EZEMUL
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Abstract
The incidence and densities of Legionella species in 663 water samples from both
potable and raw water sources in the Northern States of Nigeria were determined by the
direct immunofluorescence antibody (DFA) method and, buffered charcoal yeast-extract
(BCYE) culture confirmation. Polyvalent pool conjugates reactions detected Legionella -
like cells in virtually all potable water samples. Using serospecific antisera the presence of
each species and serogroup was highlighted. Of the first six serogroups of A. pneumophila,
serogroup 1 was the most predominant; it was detected in every sample. Serogroup 3 was
second in predominance, 87.5% of the water samples exhibited fluorescing cells of
Legionella morphology. The least detected of the serogroups was serogroup 5; it was
found in only 25% of the samples. Serogroup 6 also was detected in 42.5% of the samples.
Among the remaining species of Legionella. L. gormanii predominated in 85% of the
samples, followed by L. micdadei (82.5%). L. bozemanii was the least detected of all
Legionella species; only 17.5% of the water samples showed cells that were consistent with
Legionella morphology.
Detection rates was highest in public and private tap water samples (100%). Hotels
water samples comprising mainly of water from air-conditioning cooling systems were 96%
positive whereas hospitals were 94% positive for Legionella - like bacteria. This high
percentage rate dropped for boreholes water samples. Isolation rates were much lower;
public and private tap water samples had culturable legionellae in 20% of the samples.
Hotels water samples had isolatable legionellae in 66.7% of the samples, while hospitals
water samples were 38% positive for legionellae. Boreholes water samples had culturable
legionellae in 25% of the samples screened, while well water samples were 60% positive for
Legionella spp.
Raw water samples (246) from all the states demonstrated Legionella - like cells at
varying degrees, from 40% in Abuja to 58% in Bauchi State by polyvalent pool conjugate
reaction. Using serospecific antisera, the detection rates increased across all the states
sampling areas, the lowest detection rate was 61% in Katsina state to 86% in Gongola State.
The interstate variation in relative abundance of Legiomllaceae was less than the
intraspecies variation. Among the species in all the states. L. bozemanii serogroup 1 was the
least detected of all, only 47% of the samples demonstrated fluorescing cells characteristic of
Legionella morphology. Among the serogroups of L. pneumophila, serogroup 5 was the
least detected (51%). The occurrence of other serogroups or species ranged from 65% to
98% of/,, pneumophila, whereas the other species were 47.1% to 86%. The population
densities, for the most part ranged from 104 to 106 cells/ml.
L. pneumophila, the type species, demonstrated the wide spread nature of the first
six serogroups in all the states. However, there was a remarkable intraserotypic as well as
intrasampling area variation with one or more serotypes predominating in any one given
state. Serogroup 5 and 6 were least detected in most states' sampling areas.
Of the 98% (49 out of 50) positive samples, by immunofluorescence, only 46% (23
samples) were positive by culture. These positive samples comprised of 5 rivers. 11 dams. 3
lakes. 2 creeks, one stream, and one pond. However, there were no culturable legionellae in
water samples from Benue and Gongola States.
This study has demonstrated the wide distribution of legionellae in our environmental
water samples and underscored the need for surveillance and continued monitoring of this
group of pathogenic bacteria especially in public buildings and hospitals.
Description
A thesis submitted to Ahmadu Bello University Zaria, in partial fulfillment of the
requirements for the degree of
Doctor of Philosophy in Microbiology
Department of Microbiology
Faculty of Science
Keywords
BACTERIOLOGICAL, SURVEY, LEGIONELLA, SPECIES, NORTHERN, STATES, NIGERIA