Surface survey, 720 swabs, three wards

Microbiology research poster example

A microbiology research poster example should show the sampling plan, how the plates were read and a ranking a reader can trust, because raw colony counts rarely travel between laboratories. This A0 portrait board reports a fictional study of 720 swabs from eight surface types in three hospital wards, with one ranked bar chart of median load, a four bar comparison panel, a single 6x stat block and four cleaning actions.

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The whole board

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Bacterial load on eight ward surfaces: 720 swabs across three hospital wards

A. Ferreiro ¹, L. Nwosu ¹, S. Hedlund ²

1 Department of Microbiology, Thornbury University · 2 Infection Prevention Unit, Greenfold Hospital

ABSTRACT

Cleaning schedules treat a ward as one surface. This study took 720 swabs, 30 from each of eight surface types in each of three wards, and counted colonies at 48 hours. Median load ran from 60 units per 100 sq cm on bed rails to 10 on door handles.

Figure 1. Median load by surface: Rail, Table, Call button, Pump, Chair, Curtain, Tap, Handle.

Source: 720 swabs, counts read at 48 hours.

RESULTS

Bed rails carried a median 60 colony forming units per 100 square centimetres and door handles 10, a difference of six times. Three hundred and three of the 720 swabs sat above the 25 unit threshold, which is 42 per cent, and the four surfaces at the bedside account for 216 of those.

MEDIAN LOAD BY SURFACE

Bed rail

Door handle

Over bed table

Sink tap

DISCUSSION

The ranking is the finding, not the absolute counts, because a swab count depends on the template, the swab and the time since the last clean, and none of those transfers cleanly between studies. What does transfer is the order: the four surfaces at the bedside carried more than the four at the room edge in every one of the three wards, and the gap between highest and lowest was a factor of six. That points at frequency rather than at technique. A bed rail cleaned once a day is clean for an hour and touched for the next twenty three, so a schedule that adds a second pass on four surfaces would do more than a deeper single clean of everything.

INTRODUCTION

Ward cleaning is audited by whether a surface was cleaned, not by what is on it afterwards, and the two questions have different answers. A bed rail is touched by everyone who comes near the patient and cleaned on the same schedule as a door frame nobody touches.

METHODS

Sites. Three inpatient wards in one hospital, general medical, surgical and rehabilitation, all cleaned by one contracted service to one daily schedule.

Sampling. Eight surface types swabbed 30 times in each ward, 720 swabs in total, always between two and four hours after the daily clean and never during an outbreak period.

Technique. A 100 square centimetre template, one moistened swab worked in two directions across the whole area, transported cold and plated within 90 minutes.

Counting. Plates read at 48 hours by one microbiologist who did not know the surface or the ward, with counts recorded as colony forming units per 100 square centimetres.

Analysis. Median reported over the 90 swabs of each surface because the counts are skewed, with the share of all 720 swabs above a 25 unit per 100 square centimetre action threshold alongside.

Block by block

What each block on the board is for, in the order a reader walks it.

Title band and authors: The title says what was measured and how much of it: bacterial load on eight ward surfaces, 720 swabs across three hospital wards. Three authors sit under it over two affiliations, a university microbiology department and the hospital infection prevention unit, so a reader can see that the laboratory and the ward both stand behind the counts.
Abstract: Three sentences: cleaning schedules treat a ward as one surface; 720 swabs were taken, 30 from each of eight surface types in each of three wards, and counted at 48 hours; median load ran from 60 units per 100 square centimetres on bed rails to 10 on door handles. It gives the range before any interpretation, which is the order a laboratory audience expects.
Figure 1, median load by surface: Eight vertical bars in rank order: rail 60, table 48, call button 41, pump 34, chair 26, curtain 22, tap 15 and handle 10 colony forming units per 100 square centimetres. One word labels keep the axis clear, the caption spells out the full names, and the source line gives 720 swabs read at 48 hours. The first four bars are the bedside surfaces and the last four the room edge, so the split shows without a legend.
Results: The results block gives the six times gap between bed rails and door handles, then 303 of the 720 swabs above the 25 unit threshold, 42 per cent, with 216 of them from the four bedside surfaces. Those four surfaces account for 360 swabs, so about 60 per cent of bedside swabs sat above threshold against 87 of 360, about 24 per cent, at the room edge.
The four bar comparison panel: A bar block headed Median load by surface repeats four of the eight medians: bed rail 60, door handle 10, over bed table 48 and sink tap 15. Pairing the highest and lowest surface first, then a second high and low pair, reads as a contrast rather than a ranking, which the chart already gives. The block takes up to six rows on this layout, so pick the pairs that carry your argument and leave the full order to the chart.
Discussion: The discussion argues that the ranking transfers between studies and the counts do not, because a swab count depends on the template, the swab and the time since the last clean. It notes that the bedside four carried more than the room edge four in every ward, and turns that into a point about frequency: a rail cleaned once a day is clean for an hour and touched for the next twenty three.
Introduction and methods: The introduction sits at the top of the right column: wards are audited by whether a surface was cleaned, not by what is on it afterwards. Five labelled entries follow. Sites names three wards cleaned by one contracted service; Sampling gives 30 swabs per surface per ward, two to four hours after the daily clean; Technique gives the 100 square centimetre template and plating within 90 minutes; Counting names one microbiologist blind to surface and ward; Analysis explains the medians.
Stat block, conclusions and actions: One stat block prints 6x with the label more on bed rails than door handles and both medians underneath. The conclusions callout puts the bedside four at 2.5 times the room edge four, which matches the chart if you average its medians: 45.75 against 18.25. Four checked actions follow, from a second daily clean of rails and tables to auditing by swab count, and three numbered references close the column.
Why medians, not ranges: The Analysis entry reports a median for each surface over its 90 swabs and one overall share above the 25 unit threshold, 303 of 720 swabs or 42 percent. Medians suit swab counts, which skew hard when a few surfaces carry heavy growth. If you want spread on your board, print the eight interquartile ranges in the results text, because the figure block cannot draw error bars or ranges.

What makes this board work

Ranked bars split the ward in two

The chart orders the eight medians from 60 down to 10, and the four bedside surfaces fill the left half of it. A reader sees the bedside against room edge split before reading a word, which is the whole argument of the board, and the stat block and callout then only have to put numbers on it.

The ranking is separated from the counts

The discussion states plainly that an absolute swab count depends on the template, the swab and the time since the last clean, and that the order is what transfers. A microbiology poster that claims its raw counts are comparable across sites usually gets asked why.

The conclusion is an action

Four checked recommendations name the surfaces and the frequency: a second daily clean of bed rails and over bed tables, and the call button and pump keypad at every shift change. A ward manager can act on that list without reading the methods.

Questions people ask

What goes on a microbiology research poster?

The question, the sampling plan with its swab counts, the technique in enough detail to repeat, how plates were read and by whom, the results as medians with their spread, and the limits of comparing raw counts between studies. A threshold, if you use one, belongs in the methods with its units, and every figure should name the count it rests on.

Should I report mean or median colony counts?

Median, with the interquartile range, because colony counts are skewed and a single heavy swab moves a mean a long way. This board prints medians only and its methods say so, so it makes no claim about how much the surfaces overlap. If you add ranges, print them in the results text, since the chart block draws bars without error bars.

Can I compare my counts to a published study?

Rarely, and the board should say so. Template size, swab type, transport time and the gap since the last clean all move an absolute count. Rank order and the share above a stated threshold travel better, which is why this poster leads with a ranked chart and says in its discussion that the order, not the count, is the finding.

How do I choose an action threshold for surface swabs?

Take it from a published hygiene standard or your own infection prevention policy, state the units and the swab area, and set it before the plates are read. A threshold chosen after seeing the data invites the question of why that value. Report the share above it per surface, not only overall, because the per surface share is what a cleaning team acts on.

Why blind the person reading the plates?

Because counting colonies involves judgement at the edges: merged colonies, spreading growth and plates near the countable limit. A reader who knows the plate came from a bed rail may count it differently from one who thinks it came from a door handle. One line in methods saying the reader was blind to surface and ward, as here, answers that question before anyone asks it.

Which surfaces belong in a comparison bar panel?

The pairs that carry the argument, not a second copy of the chart. This board pairs the highest and lowest surface, then another high and low pair, so the panel reads as a contrast. If your finding is a threshold rather than a gap, list the surfaces nearest the threshold instead. Keep labels short enough to fit one line at A0.

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Sources

Written and checked by the OneCraft team. Last checked 29 September 2026.